The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_subr.c

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    1 /*-
    2  * Copyright (c) 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * (c) UNIX System Laboratories, Inc.
    5  * All or some portions of this file are derived from material licensed
    6  * to the University of California by American Telephone and Telegraph
    7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    8  * the permission of UNIX System Laboratories, Inc.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)vfs_subr.c  8.31 (Berkeley) 5/26/95
   35  */
   36 
   37 /*
   38  * External virtual filesystem routines
   39  */
   40 
   41 #include <sys/cdefs.h>
   42 __FBSDID("$FreeBSD: releng/10.4/sys/kern/vfs_subr.c 316543 2017-04-05 21:08:26Z brooks $");
   43 
   44 #include "opt_compat.h"
   45 #include "opt_ddb.h"
   46 #include "opt_watchdog.h"
   47 
   48 #include <sys/param.h>
   49 #include <sys/systm.h>
   50 #include <sys/bio.h>
   51 #include <sys/buf.h>
   52 #include <sys/condvar.h>
   53 #include <sys/conf.h>
   54 #include <sys/dirent.h>
   55 #include <sys/event.h>
   56 #include <sys/eventhandler.h>
   57 #include <sys/extattr.h>
   58 #include <sys/file.h>
   59 #include <sys/fcntl.h>
   60 #include <sys/jail.h>
   61 #include <sys/kdb.h>
   62 #include <sys/kernel.h>
   63 #include <sys/kthread.h>
   64 #include <sys/lockf.h>
   65 #include <sys/malloc.h>
   66 #include <sys/mount.h>
   67 #include <sys/namei.h>
   68 #include <sys/pctrie.h>
   69 #include <sys/priv.h>
   70 #include <sys/reboot.h>
   71 #include <sys/rwlock.h>
   72 #include <sys/sched.h>
   73 #include <sys/sleepqueue.h>
   74 #include <sys/smp.h>
   75 #include <sys/stat.h>
   76 #include <sys/sysctl.h>
   77 #include <sys/syslog.h>
   78 #include <sys/vmmeter.h>
   79 #include <sys/vnode.h>
   80 #include <sys/watchdog.h>
   81 
   82 #include <machine/stdarg.h>
   83 
   84 #include <security/mac/mac_framework.h>
   85 
   86 #include <vm/vm.h>
   87 #include <vm/vm_object.h>
   88 #include <vm/vm_extern.h>
   89 #include <vm/pmap.h>
   90 #include <vm/vm_map.h>
   91 #include <vm/vm_page.h>
   92 #include <vm/vm_kern.h>
   93 #include <vm/uma.h>
   94 
   95 #ifdef DDB
   96 #include <ddb/ddb.h>
   97 #endif
   98 
   99 static void     delmntque(struct vnode *vp);
  100 static int      flushbuflist(struct bufv *bufv, int flags, struct bufobj *bo,
  101                     int slpflag, int slptimeo);
  102 static void     syncer_shutdown(void *arg, int howto);
  103 static int      vtryrecycle(struct vnode *vp);
  104 static void     v_incr_usecount(struct vnode *);
  105 static void     v_decr_usecount(struct vnode *);
  106 static void     v_decr_useonly(struct vnode *);
  107 static void     v_upgrade_usecount(struct vnode *);
  108 static void     vnlru_free(int);
  109 static void     vgonel(struct vnode *);
  110 static void     vfs_knllock(void *arg);
  111 static void     vfs_knlunlock(void *arg);
  112 static void     vfs_knl_assert_locked(void *arg);
  113 static void     vfs_knl_assert_unlocked(void *arg);
  114 static void     destroy_vpollinfo(struct vpollinfo *vi);
  115 
  116 /*
  117  * Number of vnodes in existence.  Increased whenever getnewvnode()
  118  * allocates a new vnode, decreased in vdropl() for VI_DOOMED vnode.
  119  */
  120 static unsigned long    numvnodes;
  121 
  122 SYSCTL_ULONG(_vfs, OID_AUTO, numvnodes, CTLFLAG_RD, &numvnodes, 0,
  123     "Number of vnodes in existence");
  124 
  125 static u_long vnodes_created;
  126 SYSCTL_ULONG(_vfs, OID_AUTO, vnodes_created, CTLFLAG_RD, &vnodes_created,
  127     0, "Number of vnodes created by getnewvnode");
  128 
  129 /*
  130  * Conversion tables for conversion from vnode types to inode formats
  131  * and back.
  132  */
  133 enum vtype iftovt_tab[16] = {
  134         VNON, VFIFO, VCHR, VNON, VDIR, VNON, VBLK, VNON,
  135         VREG, VNON, VLNK, VNON, VSOCK, VNON, VNON, VBAD,
  136 };
  137 int vttoif_tab[10] = {
  138         0, S_IFREG, S_IFDIR, S_IFBLK, S_IFCHR, S_IFLNK,
  139         S_IFSOCK, S_IFIFO, S_IFMT, S_IFMT
  140 };
  141 
  142 /*
  143  * List of vnodes that are ready for recycling.
  144  */
  145 static TAILQ_HEAD(freelst, vnode) vnode_free_list;
  146 
  147 /*
  148  * Free vnode target.  Free vnodes may simply be files which have been stat'd
  149  * but not read.  This is somewhat common, and a small cache of such files
  150  * should be kept to avoid recreation costs.
  151  */
  152 static u_long wantfreevnodes;
  153 SYSCTL_ULONG(_vfs, OID_AUTO, wantfreevnodes, CTLFLAG_RW, &wantfreevnodes, 0, "");
  154 /* Number of vnodes in the free list. */
  155 static u_long freevnodes;
  156 SYSCTL_ULONG(_vfs, OID_AUTO, freevnodes, CTLFLAG_RD, &freevnodes, 0,
  157     "Number of vnodes in the free list");
  158 
  159 static int vlru_allow_cache_src;
  160 SYSCTL_INT(_vfs, OID_AUTO, vlru_allow_cache_src, CTLFLAG_RW,
  161     &vlru_allow_cache_src, 0, "Allow vlru to reclaim source vnode");
  162 
  163 static u_long recycles_count;
  164 SYSCTL_ULONG(_vfs, OID_AUTO, recycles, CTLFLAG_RD, &recycles_count, 0,
  165     "Number of vnodes recycled to avoid exceding kern.maxvnodes");
  166 
  167 /*
  168  * Various variables used for debugging the new implementation of
  169  * reassignbuf().
  170  * XXX these are probably of (very) limited utility now.
  171  */
  172 static int reassignbufcalls;
  173 SYSCTL_INT(_vfs, OID_AUTO, reassignbufcalls, CTLFLAG_RW, &reassignbufcalls, 0,
  174     "Number of calls to reassignbuf");
  175 
  176 static u_long free_owe_inact;
  177 SYSCTL_ULONG(_vfs, OID_AUTO, free_owe_inact, CTLFLAG_RD, &free_owe_inact, 0,
  178     "Number of times free vnodes kept on active list due to VFS "
  179     "owing inactivation");
  180 
  181 /*
  182  * Cache for the mount type id assigned to NFS.  This is used for
  183  * special checks in nfs/nfs_nqlease.c and vm/vnode_pager.c.
  184  */
  185 int     nfs_mount_type = -1;
  186 
  187 /* To keep more than one thread at a time from running vfs_getnewfsid */
  188 static struct mtx mntid_mtx;
  189 
  190 /*
  191  * Lock for any access to the following:
  192  *      vnode_free_list
  193  *      numvnodes
  194  *      freevnodes
  195  */
  196 static struct mtx vnode_free_list_mtx;
  197 
  198 /* Publicly exported FS */
  199 struct nfs_public nfs_pub;
  200 
  201 static uma_zone_t buf_trie_zone;
  202 
  203 /* Zone for allocation of new vnodes - used exclusively by getnewvnode() */
  204 static uma_zone_t vnode_zone;
  205 static uma_zone_t vnodepoll_zone;
  206 
  207 /*
  208  * The workitem queue.
  209  *
  210  * It is useful to delay writes of file data and filesystem metadata
  211  * for tens of seconds so that quickly created and deleted files need
  212  * not waste disk bandwidth being created and removed. To realize this,
  213  * we append vnodes to a "workitem" queue. When running with a soft
  214  * updates implementation, most pending metadata dependencies should
  215  * not wait for more than a few seconds. Thus, mounted on block devices
  216  * are delayed only about a half the time that file data is delayed.
  217  * Similarly, directory updates are more critical, so are only delayed
  218  * about a third the time that file data is delayed. Thus, there are
  219  * SYNCER_MAXDELAY queues that are processed round-robin at a rate of
  220  * one each second (driven off the filesystem syncer process). The
  221  * syncer_delayno variable indicates the next queue that is to be processed.
  222  * Items that need to be processed soon are placed in this queue:
  223  *
  224  *      syncer_workitem_pending[syncer_delayno]
  225  *
  226  * A delay of fifteen seconds is done by placing the request fifteen
  227  * entries later in the queue:
  228  *
  229  *      syncer_workitem_pending[(syncer_delayno + 15) & syncer_mask]
  230  *
  231  */
  232 static int syncer_delayno;
  233 static long syncer_mask;
  234 LIST_HEAD(synclist, bufobj);
  235 static struct synclist *syncer_workitem_pending;
  236 /*
  237  * The sync_mtx protects:
  238  *      bo->bo_synclist
  239  *      sync_vnode_count
  240  *      syncer_delayno
  241  *      syncer_state
  242  *      syncer_workitem_pending
  243  *      syncer_worklist_len
  244  *      rushjob
  245  */
  246 static struct mtx sync_mtx;
  247 static struct cv sync_wakeup;
  248 
  249 #define SYNCER_MAXDELAY         32
  250 static int syncer_maxdelay = SYNCER_MAXDELAY;   /* maximum delay time */
  251 static int syncdelay = 30;              /* max time to delay syncing data */
  252 static int filedelay = 30;              /* time to delay syncing files */
  253 SYSCTL_INT(_kern, OID_AUTO, filedelay, CTLFLAG_RW, &filedelay, 0,
  254     "Time to delay syncing files (in seconds)");
  255 static int dirdelay = 29;               /* time to delay syncing directories */
  256 SYSCTL_INT(_kern, OID_AUTO, dirdelay, CTLFLAG_RW, &dirdelay, 0,
  257     "Time to delay syncing directories (in seconds)");
  258 static int metadelay = 28;              /* time to delay syncing metadata */
  259 SYSCTL_INT(_kern, OID_AUTO, metadelay, CTLFLAG_RW, &metadelay, 0,
  260     "Time to delay syncing metadata (in seconds)");
  261 static int rushjob;             /* number of slots to run ASAP */
  262 static int stat_rush_requests;  /* number of times I/O speeded up */
  263 SYSCTL_INT(_debug, OID_AUTO, rush_requests, CTLFLAG_RW, &stat_rush_requests, 0,
  264     "Number of times I/O speeded up (rush requests)");
  265 
  266 /*
  267  * When shutting down the syncer, run it at four times normal speed.
  268  */
  269 #define SYNCER_SHUTDOWN_SPEEDUP         4
  270 static int sync_vnode_count;
  271 static int syncer_worklist_len;
  272 static enum { SYNCER_RUNNING, SYNCER_SHUTTING_DOWN, SYNCER_FINAL_DELAY }
  273     syncer_state;
  274 
  275 /*
  276  * Number of vnodes we want to exist at any one time.  This is mostly used
  277  * to size hash tables in vnode-related code.  It is normally not used in
  278  * getnewvnode(), as wantfreevnodes is normally nonzero.)
  279  *
  280  * XXX desiredvnodes is historical cruft and should not exist.
  281  */
  282 int desiredvnodes;
  283 
  284 static int
  285 sysctl_update_desiredvnodes(SYSCTL_HANDLER_ARGS)
  286 {
  287         int error, old_desiredvnodes;
  288 
  289         old_desiredvnodes = desiredvnodes;
  290         if ((error = sysctl_handle_int(oidp, arg1, arg2, req)) != 0)
  291                 return (error);
  292         if (old_desiredvnodes != desiredvnodes) {
  293                 vfs_hash_changesize(desiredvnodes);
  294                 cache_changesize(desiredvnodes);
  295         }
  296         return (0);
  297 }
  298 
  299 SYSCTL_PROC(_kern, KERN_MAXVNODES, maxvnodes,
  300     CTLTYPE_INT | CTLFLAG_MPSAFE | CTLFLAG_RW, &desiredvnodes, 0,
  301     sysctl_update_desiredvnodes, "I", "Maximum number of vnodes");
  302 SYSCTL_ULONG(_kern, OID_AUTO, minvnodes, CTLFLAG_RW,
  303     &wantfreevnodes, 0, "Minimum number of vnodes (legacy)");
  304 static int vnlru_nowhere;
  305 SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RW,
  306     &vnlru_nowhere, 0, "Number of times the vnlru process ran without success");
  307 
  308 /* Shift count for (uintptr_t)vp to initialize vp->v_hash. */
  309 static int vnsz2log;
  310 
  311 /*
  312  * Support for the bufobj clean & dirty pctrie.
  313  */
  314 static void *
  315 buf_trie_alloc(struct pctrie *ptree)
  316 {
  317 
  318         return uma_zalloc(buf_trie_zone, M_NOWAIT);
  319 }
  320 
  321 static void
  322 buf_trie_free(struct pctrie *ptree, void *node)
  323 {
  324 
  325         uma_zfree(buf_trie_zone, node);
  326 }
  327 PCTRIE_DEFINE(BUF, buf, b_lblkno, buf_trie_alloc, buf_trie_free);
  328 
  329 /*
  330  * Initialize the vnode management data structures.
  331  *
  332  * Reevaluate the following cap on the number of vnodes after the physical
  333  * memory size exceeds 512GB.  In the limit, as the physical memory size
  334  * grows, the ratio of physical pages to vnodes approaches sixteen to one.
  335  */
  336 #ifndef MAXVNODES_MAX
  337 #define MAXVNODES_MAX   (512 * (1024 * 1024 * 1024 / (int)PAGE_SIZE / 16))
  338 #endif
  339 
  340 /*
  341  * Initialize a vnode as it first enters the zone.
  342  */
  343 static int
  344 vnode_init(void *mem, int size, int flags)
  345 {
  346         struct vnode *vp;
  347         struct bufobj *bo;
  348 
  349         vp = mem;
  350         bzero(vp, size);
  351         /*
  352          * Setup locks.
  353          */
  354         vp->v_vnlock = &vp->v_lock;
  355         mtx_init(&vp->v_interlock, "vnode interlock", NULL, MTX_DEF);
  356         /*
  357          * By default, don't allow shared locks unless filesystems opt-in.
  358          */
  359         lockinit(vp->v_vnlock, PVFS, "vnode", VLKTIMEOUT,
  360             LK_NOSHARE | LK_IS_VNODE);
  361         /*
  362          * Initialize bufobj.
  363          */
  364         bo = &vp->v_bufobj;
  365         bo->__bo_vnode = vp;
  366         rw_init(BO_LOCKPTR(bo), "bufobj interlock");
  367         bo->bo_private = vp;
  368         TAILQ_INIT(&bo->bo_clean.bv_hd);
  369         TAILQ_INIT(&bo->bo_dirty.bv_hd);
  370         /*
  371          * Initialize namecache.
  372          */
  373         LIST_INIT(&vp->v_cache_src);
  374         TAILQ_INIT(&vp->v_cache_dst);
  375         /*
  376          * Initialize rangelocks.
  377          */
  378         rangelock_init(&vp->v_rl);
  379         return (0);
  380 }
  381 
  382 /*
  383  * Free a vnode when it is cleared from the zone.
  384  */
  385 static void
  386 vnode_fini(void *mem, int size)
  387 {
  388         struct vnode *vp;
  389         struct bufobj *bo;
  390 
  391         vp = mem;
  392         rangelock_destroy(&vp->v_rl);
  393         lockdestroy(vp->v_vnlock);
  394         mtx_destroy(&vp->v_interlock);
  395         bo = &vp->v_bufobj;
  396         rw_destroy(BO_LOCKPTR(bo));
  397 }
  398 
  399 static void
  400 vntblinit(void *dummy __unused)
  401 {
  402         u_int i;
  403         int physvnodes, virtvnodes;
  404 
  405         /*
  406          * Desiredvnodes is a function of the physical memory size and the
  407          * kernel's heap size.  Generally speaking, it scales with the
  408          * physical memory size.  The ratio of desiredvnodes to physical pages
  409          * is one to four until desiredvnodes exceeds 98,304.  Thereafter, the
  410          * marginal ratio of desiredvnodes to physical pages is one to
  411          * sixteen.  However, desiredvnodes is limited by the kernel's heap
  412          * size.  The memory required by desiredvnodes vnodes and vm objects
  413          * may not exceed one seventh of the kernel's heap size.
  414          */
  415         physvnodes = maxproc + cnt.v_page_count / 16 + 3 * min(98304 * 4,
  416             cnt.v_page_count) / 16;
  417         virtvnodes = vm_kmem_size / (7 * (sizeof(struct vm_object) +
  418             sizeof(struct vnode)));
  419         desiredvnodes = min(physvnodes, virtvnodes);
  420         if (desiredvnodes > MAXVNODES_MAX) {
  421                 if (bootverbose)
  422                         printf("Reducing kern.maxvnodes %d -> %d\n",
  423                             desiredvnodes, MAXVNODES_MAX);
  424                 desiredvnodes = MAXVNODES_MAX;
  425         }
  426         wantfreevnodes = desiredvnodes / 4;
  427         mtx_init(&mntid_mtx, "mntid", NULL, MTX_DEF);
  428         TAILQ_INIT(&vnode_free_list);
  429         mtx_init(&vnode_free_list_mtx, "vnode_free_list", NULL, MTX_DEF);
  430         vnode_zone = uma_zcreate("VNODE", sizeof (struct vnode), NULL, NULL,
  431             vnode_init, vnode_fini, UMA_ALIGN_PTR, 0);
  432         vnodepoll_zone = uma_zcreate("VNODEPOLL", sizeof (struct vpollinfo),
  433             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
  434         /*
  435          * Preallocate enough nodes to support one-per buf so that
  436          * we can not fail an insert.  reassignbuf() callers can not
  437          * tolerate the insertion failure.
  438          */
  439         buf_trie_zone = uma_zcreate("BUF TRIE", pctrie_node_size(),
  440             NULL, NULL, pctrie_zone_init, NULL, UMA_ALIGN_PTR, 
  441             UMA_ZONE_NOFREE | UMA_ZONE_VM);
  442         uma_prealloc(buf_trie_zone, nbuf);
  443         /*
  444          * Initialize the filesystem syncer.
  445          */
  446         syncer_workitem_pending = hashinit(syncer_maxdelay, M_VNODE,
  447             &syncer_mask);
  448         syncer_maxdelay = syncer_mask + 1;
  449         mtx_init(&sync_mtx, "Syncer mtx", NULL, MTX_DEF);
  450         cv_init(&sync_wakeup, "syncer");
  451         for (i = 1; i <= sizeof(struct vnode); i <<= 1)
  452                 vnsz2log++;
  453         vnsz2log--;
  454 }
  455 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_FIRST, vntblinit, NULL);
  456 
  457 
  458 /*
  459  * Mark a mount point as busy. Used to synchronize access and to delay
  460  * unmounting. Eventually, mountlist_mtx is not released on failure.
  461  *
  462  * vfs_busy() is a custom lock, it can block the caller.
  463  * vfs_busy() only sleeps if the unmount is active on the mount point.
  464  * For a mountpoint mp, vfs_busy-enforced lock is before lock of any
  465  * vnode belonging to mp.
  466  *
  467  * Lookup uses vfs_busy() to traverse mount points.
  468  * root fs                      var fs
  469  * / vnode lock         A       / vnode lock (/var)             D
  470  * /var vnode lock      B       /log vnode lock(/var/log)       E
  471  * vfs_busy lock        C       vfs_busy lock                   F
  472  *
  473  * Within each file system, the lock order is C->A->B and F->D->E.
  474  *
  475  * When traversing across mounts, the system follows that lock order:
  476  *
  477  *        C->A->B
  478  *              |
  479  *              +->F->D->E
  480  *
  481  * The lookup() process for namei("/var") illustrates the process:
  482  *  VOP_LOOKUP() obtains B while A is held
  483  *  vfs_busy() obtains a shared lock on F while A and B are held
  484  *  vput() releases lock on B
  485  *  vput() releases lock on A
  486  *  VFS_ROOT() obtains lock on D while shared lock on F is held
  487  *  vfs_unbusy() releases shared lock on F
  488  *  vn_lock() obtains lock on deadfs vnode vp_crossmp instead of A.
  489  *    Attempt to lock A (instead of vp_crossmp) while D is held would
  490  *    violate the global order, causing deadlocks.
  491  *
  492  * dounmount() locks B while F is drained.
  493  */
  494 int
  495 vfs_busy(struct mount *mp, int flags)
  496 {
  497 
  498         MPASS((flags & ~MBF_MASK) == 0);
  499         CTR3(KTR_VFS, "%s: mp %p with flags %d", __func__, mp, flags);
  500 
  501         MNT_ILOCK(mp);
  502         MNT_REF(mp);
  503         /*
  504          * If mount point is currently being unmounted, sleep until the
  505          * mount point fate is decided.  If thread doing the unmounting fails,
  506          * it will clear MNTK_UNMOUNT flag before waking us up, indicating
  507          * that this mount point has survived the unmount attempt and vfs_busy
  508          * should retry.  Otherwise the unmounter thread will set MNTK_REFEXPIRE
  509          * flag in addition to MNTK_UNMOUNT, indicating that mount point is
  510          * about to be really destroyed.  vfs_busy needs to release its
  511          * reference on the mount point in this case and return with ENOENT,
  512          * telling the caller that mount mount it tried to busy is no longer
  513          * valid.
  514          */
  515         while (mp->mnt_kern_flag & MNTK_UNMOUNT) {
  516                 if (flags & MBF_NOWAIT || mp->mnt_kern_flag & MNTK_REFEXPIRE) {
  517                         MNT_REL(mp);
  518                         MNT_IUNLOCK(mp);
  519                         CTR1(KTR_VFS, "%s: failed busying before sleeping",
  520                             __func__);
  521                         return (ENOENT);
  522                 }
  523                 if (flags & MBF_MNTLSTLOCK)
  524                         mtx_unlock(&mountlist_mtx);
  525                 mp->mnt_kern_flag |= MNTK_MWAIT;
  526                 msleep(mp, MNT_MTX(mp), PVFS | PDROP, "vfs_busy", 0);
  527                 if (flags & MBF_MNTLSTLOCK)
  528                         mtx_lock(&mountlist_mtx);
  529                 MNT_ILOCK(mp);
  530         }
  531         if (flags & MBF_MNTLSTLOCK)
  532                 mtx_unlock(&mountlist_mtx);
  533         mp->mnt_lockref++;
  534         MNT_IUNLOCK(mp);
  535         return (0);
  536 }
  537 
  538 /*
  539  * Free a busy filesystem.
  540  */
  541 void
  542 vfs_unbusy(struct mount *mp)
  543 {
  544 
  545         CTR2(KTR_VFS, "%s: mp %p", __func__, mp);
  546         MNT_ILOCK(mp);
  547         MNT_REL(mp);
  548         KASSERT(mp->mnt_lockref > 0, ("negative mnt_lockref"));
  549         mp->mnt_lockref--;
  550         if (mp->mnt_lockref == 0 && (mp->mnt_kern_flag & MNTK_DRAINING) != 0) {
  551                 MPASS(mp->mnt_kern_flag & MNTK_UNMOUNT);
  552                 CTR1(KTR_VFS, "%s: waking up waiters", __func__);
  553                 mp->mnt_kern_flag &= ~MNTK_DRAINING;
  554                 wakeup(&mp->mnt_lockref);
  555         }
  556         MNT_IUNLOCK(mp);
  557 }
  558 
  559 /*
  560  * Lookup a mount point by filesystem identifier.
  561  */
  562 struct mount *
  563 vfs_getvfs(fsid_t *fsid)
  564 {
  565         struct mount *mp;
  566 
  567         CTR2(KTR_VFS, "%s: fsid %p", __func__, fsid);
  568         mtx_lock(&mountlist_mtx);
  569         TAILQ_FOREACH(mp, &mountlist, mnt_list) {
  570                 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
  571                     mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
  572                         vfs_ref(mp);
  573                         mtx_unlock(&mountlist_mtx);
  574                         return (mp);
  575                 }
  576         }
  577         mtx_unlock(&mountlist_mtx);
  578         CTR2(KTR_VFS, "%s: lookup failed for %p id", __func__, fsid);
  579         return ((struct mount *) 0);
  580 }
  581 
  582 /*
  583  * Lookup a mount point by filesystem identifier, busying it before
  584  * returning.
  585  *
  586  * To avoid congestion on mountlist_mtx, implement simple direct-mapped
  587  * cache for popular filesystem identifiers.  The cache is lockess, using
  588  * the fact that struct mount's are never freed.  In worst case we may
  589  * get pointer to unmounted or even different filesystem, so we have to
  590  * check what we got, and go slow way if so.
  591  */
  592 struct mount *
  593 vfs_busyfs(fsid_t *fsid)
  594 {
  595 #define FSID_CACHE_SIZE 256
  596         typedef struct mount * volatile vmp_t;
  597         static vmp_t cache[FSID_CACHE_SIZE];
  598         struct mount *mp;
  599         int error;
  600         uint32_t hash;
  601 
  602         CTR2(KTR_VFS, "%s: fsid %p", __func__, fsid);
  603         hash = fsid->val[0] ^ fsid->val[1];
  604         hash = (hash >> 16 ^ hash) & (FSID_CACHE_SIZE - 1);
  605         mp = cache[hash];
  606         if (mp == NULL ||
  607             mp->mnt_stat.f_fsid.val[0] != fsid->val[0] ||
  608             mp->mnt_stat.f_fsid.val[1] != fsid->val[1])
  609                 goto slow;
  610         if (vfs_busy(mp, 0) != 0) {
  611                 cache[hash] = NULL;
  612                 goto slow;
  613         }
  614         if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
  615             mp->mnt_stat.f_fsid.val[1] == fsid->val[1])
  616                 return (mp);
  617         else
  618             vfs_unbusy(mp);
  619 
  620 slow:
  621         mtx_lock(&mountlist_mtx);
  622         TAILQ_FOREACH(mp, &mountlist, mnt_list) {
  623                 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
  624                     mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
  625                         error = vfs_busy(mp, MBF_MNTLSTLOCK);
  626                         if (error) {
  627                                 cache[hash] = NULL;
  628                                 mtx_unlock(&mountlist_mtx);
  629                                 return (NULL);
  630                         }
  631                         cache[hash] = mp;
  632                         return (mp);
  633                 }
  634         }
  635         CTR2(KTR_VFS, "%s: lookup failed for %p id", __func__, fsid);
  636         mtx_unlock(&mountlist_mtx);
  637         return ((struct mount *) 0);
  638 }
  639 
  640 /*
  641  * Check if a user can access privileged mount options.
  642  */
  643 int
  644 vfs_suser(struct mount *mp, struct thread *td)
  645 {
  646         int error;
  647 
  648         /*
  649          * If the thread is jailed, but this is not a jail-friendly file
  650          * system, deny immediately.
  651          */
  652         if (!(mp->mnt_vfc->vfc_flags & VFCF_JAIL) && jailed(td->td_ucred))
  653                 return (EPERM);
  654 
  655         /*
  656          * If the file system was mounted outside the jail of the calling
  657          * thread, deny immediately.
  658          */
  659         if (prison_check(td->td_ucred, mp->mnt_cred) != 0)
  660                 return (EPERM);
  661 
  662         /*
  663          * If file system supports delegated administration, we don't check
  664          * for the PRIV_VFS_MOUNT_OWNER privilege - it will be better verified
  665          * by the file system itself.
  666          * If this is not the user that did original mount, we check for
  667          * the PRIV_VFS_MOUNT_OWNER privilege.
  668          */
  669         if (!(mp->mnt_vfc->vfc_flags & VFCF_DELEGADMIN) &&
  670             mp->mnt_cred->cr_uid != td->td_ucred->cr_uid) {
  671                 if ((error = priv_check(td, PRIV_VFS_MOUNT_OWNER)) != 0)
  672                         return (error);
  673         }
  674         return (0);
  675 }
  676 
  677 /*
  678  * Get a new unique fsid.  Try to make its val[0] unique, since this value
  679  * will be used to create fake device numbers for stat().  Also try (but
  680  * not so hard) make its val[0] unique mod 2^16, since some emulators only
  681  * support 16-bit device numbers.  We end up with unique val[0]'s for the
  682  * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls.
  683  *
  684  * Keep in mind that several mounts may be running in parallel.  Starting
  685  * the search one past where the previous search terminated is both a
  686  * micro-optimization and a defense against returning the same fsid to
  687  * different mounts.
  688  */
  689 void
  690 vfs_getnewfsid(struct mount *mp)
  691 {
  692         static uint16_t mntid_base;
  693         struct mount *nmp;
  694         fsid_t tfsid;
  695         int mtype;
  696 
  697         CTR2(KTR_VFS, "%s: mp %p", __func__, mp);
  698         mtx_lock(&mntid_mtx);
  699         mtype = mp->mnt_vfc->vfc_typenum;
  700         tfsid.val[1] = mtype;
  701         mtype = (mtype & 0xFF) << 24;
  702         for (;;) {
  703                 tfsid.val[0] = makedev(255,
  704                     mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF));
  705                 mntid_base++;
  706                 if ((nmp = vfs_getvfs(&tfsid)) == NULL)
  707                         break;
  708                 vfs_rel(nmp);
  709         }
  710         mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
  711         mp->mnt_stat.f_fsid.val[1] = tfsid.val[1];
  712         mtx_unlock(&mntid_mtx);
  713 }
  714 
  715 /*
  716  * Knob to control the precision of file timestamps:
  717  *
  718  *   0 = seconds only; nanoseconds zeroed.
  719  *   1 = seconds and nanoseconds, accurate within 1/HZ.
  720  *   2 = seconds and nanoseconds, truncated to microseconds.
  721  * >=3 = seconds and nanoseconds, maximum precision.
  722  */
  723 enum { TSP_SEC, TSP_HZ, TSP_USEC, TSP_NSEC };
  724 
  725 static int timestamp_precision = TSP_USEC;
  726 SYSCTL_INT(_vfs, OID_AUTO, timestamp_precision, CTLFLAG_RW,
  727     &timestamp_precision, 0, "File timestamp precision (0: seconds, "
  728     "1: sec + ns accurate to 1/HZ, 2: sec + ns truncated to ms, "
  729     "3+: sec + ns (max. precision))");
  730 
  731 /*
  732  * Get a current timestamp.
  733  */
  734 void
  735 vfs_timestamp(struct timespec *tsp)
  736 {
  737         struct timeval tv;
  738 
  739         switch (timestamp_precision) {
  740         case TSP_SEC:
  741                 tsp->tv_sec = time_second;
  742                 tsp->tv_nsec = 0;
  743                 break;
  744         case TSP_HZ:
  745                 getnanotime(tsp);
  746                 break;
  747         case TSP_USEC:
  748                 microtime(&tv);
  749                 TIMEVAL_TO_TIMESPEC(&tv, tsp);
  750                 break;
  751         case TSP_NSEC:
  752         default:
  753                 nanotime(tsp);
  754                 break;
  755         }
  756 }
  757 
  758 /*
  759  * Set vnode attributes to VNOVAL
  760  */
  761 void
  762 vattr_null(struct vattr *vap)
  763 {
  764 
  765         vap->va_type = VNON;
  766         vap->va_size = VNOVAL;
  767         vap->va_bytes = VNOVAL;
  768         vap->va_mode = VNOVAL;
  769         vap->va_nlink = VNOVAL;
  770         vap->va_uid = VNOVAL;
  771         vap->va_gid = VNOVAL;
  772         vap->va_fsid = VNOVAL;
  773         vap->va_fileid = VNOVAL;
  774         vap->va_blocksize = VNOVAL;
  775         vap->va_rdev = VNOVAL;
  776         vap->va_atime.tv_sec = VNOVAL;
  777         vap->va_atime.tv_nsec = VNOVAL;
  778         vap->va_mtime.tv_sec = VNOVAL;
  779         vap->va_mtime.tv_nsec = VNOVAL;
  780         vap->va_ctime.tv_sec = VNOVAL;
  781         vap->va_ctime.tv_nsec = VNOVAL;
  782         vap->va_birthtime.tv_sec = VNOVAL;
  783         vap->va_birthtime.tv_nsec = VNOVAL;
  784         vap->va_flags = VNOVAL;
  785         vap->va_gen = VNOVAL;
  786         vap->va_vaflags = 0;
  787 }
  788 
  789 /*
  790  * This routine is called when we have too many vnodes.  It attempts
  791  * to free <count> vnodes and will potentially free vnodes that still
  792  * have VM backing store (VM backing store is typically the cause
  793  * of a vnode blowout so we want to do this).  Therefore, this operation
  794  * is not considered cheap.
  795  *
  796  * A number of conditions may prevent a vnode from being reclaimed.
  797  * the buffer cache may have references on the vnode, a directory
  798  * vnode may still have references due to the namei cache representing
  799  * underlying files, or the vnode may be in active use.   It is not
  800  * desirable to reuse such vnodes.  These conditions may cause the
  801  * number of vnodes to reach some minimum value regardless of what
  802  * you set kern.maxvnodes to.  Do not set kern.maxvnodes too low.
  803  */
  804 static int
  805 vlrureclaim(struct mount *mp)
  806 {
  807         struct vnode *vp;
  808         int done;
  809         int trigger;
  810         int usevnodes;
  811         int count;
  812 
  813         /*
  814          * Calculate the trigger point, don't allow user
  815          * screwups to blow us up.   This prevents us from
  816          * recycling vnodes with lots of resident pages.  We
  817          * aren't trying to free memory, we are trying to
  818          * free vnodes.
  819          */
  820         usevnodes = desiredvnodes;
  821         if (usevnodes <= 0)
  822                 usevnodes = 1;
  823         trigger = cnt.v_page_count * 2 / usevnodes;
  824         done = 0;
  825         vn_start_write(NULL, &mp, V_WAIT);
  826         MNT_ILOCK(mp);
  827         count = mp->mnt_nvnodelistsize / 10 + 1;
  828         while (count != 0) {
  829                 vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
  830                 while (vp != NULL && vp->v_type == VMARKER)
  831                         vp = TAILQ_NEXT(vp, v_nmntvnodes);
  832                 if (vp == NULL)
  833                         break;
  834                 TAILQ_REMOVE(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
  835                 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
  836                 --count;
  837                 if (!VI_TRYLOCK(vp))
  838                         goto next_iter;
  839                 /*
  840                  * If it's been deconstructed already, it's still
  841                  * referenced, or it exceeds the trigger, skip it.
  842                  */
  843                 if (vp->v_usecount ||
  844                     (!vlru_allow_cache_src &&
  845                         !LIST_EMPTY(&(vp)->v_cache_src)) ||
  846                     (vp->v_iflag & VI_DOOMED) != 0 || (vp->v_object != NULL &&
  847                     vp->v_object->resident_page_count > trigger)) {
  848                         VI_UNLOCK(vp);
  849                         goto next_iter;
  850                 }
  851                 MNT_IUNLOCK(mp);
  852                 vholdl(vp);
  853                 if (VOP_LOCK(vp, LK_INTERLOCK|LK_EXCLUSIVE|LK_NOWAIT)) {
  854                         vdrop(vp);
  855                         goto next_iter_mntunlocked;
  856                 }
  857                 VI_LOCK(vp);
  858                 /*
  859                  * v_usecount may have been bumped after VOP_LOCK() dropped
  860                  * the vnode interlock and before it was locked again.
  861                  *
  862                  * It is not necessary to recheck VI_DOOMED because it can
  863                  * only be set by another thread that holds both the vnode
  864                  * lock and vnode interlock.  If another thread has the
  865                  * vnode lock before we get to VOP_LOCK() and obtains the
  866                  * vnode interlock after VOP_LOCK() drops the vnode
  867                  * interlock, the other thread will be unable to drop the
  868                  * vnode lock before our VOP_LOCK() call fails.
  869                  */
  870                 if (vp->v_usecount ||
  871                     (!vlru_allow_cache_src &&
  872                         !LIST_EMPTY(&(vp)->v_cache_src)) ||
  873                     (vp->v_object != NULL &&
  874                     vp->v_object->resident_page_count > trigger)) {
  875                         VOP_UNLOCK(vp, LK_INTERLOCK);
  876                         vdrop(vp);
  877                         goto next_iter_mntunlocked;
  878                 }
  879                 KASSERT((vp->v_iflag & VI_DOOMED) == 0,
  880                     ("VI_DOOMED unexpectedly detected in vlrureclaim()"));
  881                 atomic_add_long(&recycles_count, 1);
  882                 vgonel(vp);
  883                 VOP_UNLOCK(vp, 0);
  884                 vdropl(vp);
  885                 done++;
  886 next_iter_mntunlocked:
  887                 if (!should_yield())
  888                         goto relock_mnt;
  889                 goto yield;
  890 next_iter:
  891                 if (!should_yield())
  892                         continue;
  893                 MNT_IUNLOCK(mp);
  894 yield:
  895                 kern_yield(PRI_USER);
  896 relock_mnt:
  897                 MNT_ILOCK(mp);
  898         }
  899         MNT_IUNLOCK(mp);
  900         vn_finished_write(mp);
  901         return done;
  902 }
  903 
  904 /*
  905  * Attempt to keep the free list at wantfreevnodes length.
  906  */
  907 static void
  908 vnlru_free(int count)
  909 {
  910         struct vnode *vp;
  911 
  912         mtx_assert(&vnode_free_list_mtx, MA_OWNED);
  913         for (; count > 0; count--) {
  914                 vp = TAILQ_FIRST(&vnode_free_list);
  915                 /*
  916                  * The list can be modified while the free_list_mtx
  917                  * has been dropped and vp could be NULL here.
  918                  */
  919                 if (!vp)
  920                         break;
  921                 VNASSERT(vp->v_op != NULL, vp,
  922                     ("vnlru_free: vnode already reclaimed."));
  923                 KASSERT((vp->v_iflag & VI_FREE) != 0,
  924                     ("Removing vnode not on freelist"));
  925                 KASSERT((vp->v_iflag & VI_ACTIVE) == 0,
  926                     ("Mangling active vnode"));
  927                 TAILQ_REMOVE(&vnode_free_list, vp, v_actfreelist);
  928                 /*
  929                  * Don't recycle if we can't get the interlock.
  930                  */
  931                 if (!VI_TRYLOCK(vp)) {
  932                         TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_actfreelist);
  933                         continue;
  934                 }
  935                 VNASSERT((vp->v_iflag & VI_FREE) != 0 && vp->v_holdcnt == 0,
  936                     vp, ("vp inconsistent on freelist"));
  937 
  938                 /*
  939                  * The clear of VI_FREE prevents activation of the
  940                  * vnode.  There is no sense in putting the vnode on
  941                  * the mount point active list, only to remove it
  942                  * later during recycling.  Inline the relevant part
  943                  * of vholdl(), to avoid triggering assertions or
  944                  * activating.
  945                  */
  946                 freevnodes--;
  947                 vp->v_iflag &= ~VI_FREE;
  948                 vp->v_holdcnt++;
  949 
  950                 mtx_unlock(&vnode_free_list_mtx);
  951                 VI_UNLOCK(vp);
  952                 vtryrecycle(vp);
  953                 /*
  954                  * If the recycled succeeded this vdrop will actually free
  955                  * the vnode.  If not it will simply place it back on
  956                  * the free list.
  957                  */
  958                 vdrop(vp);
  959                 mtx_lock(&vnode_free_list_mtx);
  960         }
  961 }
  962 /*
  963  * Attempt to recycle vnodes in a context that is always safe to block.
  964  * Calling vlrurecycle() from the bowels of filesystem code has some
  965  * interesting deadlock problems.
  966  */
  967 static struct proc *vnlruproc;
  968 static int vnlruproc_sig;
  969 
  970 static void
  971 vnlru_proc(void)
  972 {
  973         struct mount *mp, *nmp;
  974         int done;
  975         struct proc *p = vnlruproc;
  976 
  977         EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, p,
  978             SHUTDOWN_PRI_FIRST);
  979 
  980         for (;;) {
  981                 kproc_suspend_check(p);
  982                 mtx_lock(&vnode_free_list_mtx);
  983                 if (freevnodes > wantfreevnodes)
  984                         vnlru_free(freevnodes - wantfreevnodes);
  985                 if (numvnodes <= desiredvnodes * 9 / 10) {
  986                         vnlruproc_sig = 0;
  987                         wakeup(&vnlruproc_sig);
  988                         msleep(vnlruproc, &vnode_free_list_mtx,
  989                             PVFS|PDROP, "vlruwt", hz);
  990                         continue;
  991                 }
  992                 mtx_unlock(&vnode_free_list_mtx);
  993                 done = 0;
  994                 mtx_lock(&mountlist_mtx);
  995                 for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
  996                         if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK)) {
  997                                 nmp = TAILQ_NEXT(mp, mnt_list);
  998                                 continue;
  999                         }
 1000                         done += vlrureclaim(mp);
 1001                         mtx_lock(&mountlist_mtx);
 1002                         nmp = TAILQ_NEXT(mp, mnt_list);
 1003                         vfs_unbusy(mp);
 1004                 }
 1005                 mtx_unlock(&mountlist_mtx);
 1006                 if (done == 0) {
 1007 #if 0
 1008                         /* These messages are temporary debugging aids */
 1009                         if (vnlru_nowhere < 5)
 1010                                 printf("vnlru process getting nowhere..\n");
 1011                         else if (vnlru_nowhere == 5)
 1012                                 printf("vnlru process messages stopped.\n");
 1013 #endif
 1014                         vnlru_nowhere++;
 1015                         tsleep(vnlruproc, PPAUSE, "vlrup", hz * 3);
 1016                 } else
 1017                         kern_yield(PRI_USER);
 1018         }
 1019 }
 1020 
 1021 static struct kproc_desc vnlru_kp = {
 1022         "vnlru",
 1023         vnlru_proc,
 1024         &vnlruproc
 1025 };
 1026 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start,
 1027     &vnlru_kp);
 1028  
 1029 /*
 1030  * Routines having to do with the management of the vnode table.
 1031  */
 1032 
 1033 /*
 1034  * Try to recycle a freed vnode.  We abort if anyone picks up a reference
 1035  * before we actually vgone().  This function must be called with the vnode
 1036  * held to prevent the vnode from being returned to the free list midway
 1037  * through vgone().
 1038  */
 1039 static int
 1040 vtryrecycle(struct vnode *vp)
 1041 {
 1042         struct mount *vnmp;
 1043 
 1044         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 1045         VNASSERT(vp->v_holdcnt, vp,
 1046             ("vtryrecycle: Recycling vp %p without a reference.", vp));
 1047         /*
 1048          * This vnode may found and locked via some other list, if so we
 1049          * can't recycle it yet.
 1050          */
 1051         if (VOP_LOCK(vp, LK_EXCLUSIVE | LK_NOWAIT) != 0) {
 1052                 CTR2(KTR_VFS,
 1053                     "%s: impossible to recycle, vp %p lock is already held",
 1054                     __func__, vp);
 1055                 return (EWOULDBLOCK);
 1056         }
 1057         /*
 1058          * Don't recycle if its filesystem is being suspended.
 1059          */
 1060         if (vn_start_write(vp, &vnmp, V_NOWAIT) != 0) {
 1061                 VOP_UNLOCK(vp, 0);
 1062                 CTR2(KTR_VFS,
 1063                     "%s: impossible to recycle, cannot start the write for %p",
 1064                     __func__, vp);
 1065                 return (EBUSY);
 1066         }
 1067         /*
 1068          * If we got this far, we need to acquire the interlock and see if
 1069          * anyone picked up this vnode from another list.  If not, we will
 1070          * mark it with DOOMED via vgonel() so that anyone who does find it
 1071          * will skip over it.
 1072          */
 1073         VI_LOCK(vp);
 1074         if (vp->v_usecount) {
 1075                 VOP_UNLOCK(vp, LK_INTERLOCK);
 1076                 vn_finished_write(vnmp);
 1077                 CTR2(KTR_VFS,
 1078                     "%s: impossible to recycle, %p is already referenced",
 1079                     __func__, vp);
 1080                 return (EBUSY);
 1081         }
 1082         if ((vp->v_iflag & VI_DOOMED) == 0) {
 1083                 atomic_add_long(&recycles_count, 1);
 1084                 vgonel(vp);
 1085         }
 1086         VOP_UNLOCK(vp, LK_INTERLOCK);
 1087         vn_finished_write(vnmp);
 1088         return (0);
 1089 }
 1090 
 1091 /*
 1092  * Wait for available vnodes.
 1093  */
 1094 static int
 1095 getnewvnode_wait(int suspended)
 1096 {
 1097 
 1098         mtx_assert(&vnode_free_list_mtx, MA_OWNED);
 1099         if (numvnodes > desiredvnodes) {
 1100                 if (suspended) {
 1101                         /*
 1102                          * File system is beeing suspended, we cannot risk a
 1103                          * deadlock here, so allocate new vnode anyway.
 1104                          */
 1105                         if (freevnodes > wantfreevnodes)
 1106                                 vnlru_free(freevnodes - wantfreevnodes);
 1107                         return (0);
 1108                 }
 1109                 if (vnlruproc_sig == 0) {
 1110                         vnlruproc_sig = 1;      /* avoid unnecessary wakeups */
 1111                         wakeup(vnlruproc);
 1112                 }
 1113                 msleep(&vnlruproc_sig, &vnode_free_list_mtx, PVFS,
 1114                     "vlruwk", hz);
 1115         }
 1116         return (numvnodes > desiredvnodes ? ENFILE : 0);
 1117 }
 1118 
 1119 void
 1120 getnewvnode_reserve(u_int count)
 1121 {
 1122         struct thread *td;
 1123 
 1124         td = curthread;
 1125         /* First try to be quick and racy. */
 1126         if (atomic_fetchadd_long(&numvnodes, count) + count <= desiredvnodes) {
 1127                 td->td_vp_reserv += count;
 1128                 return;
 1129         } else
 1130                 atomic_subtract_long(&numvnodes, count);
 1131 
 1132         mtx_lock(&vnode_free_list_mtx);
 1133         while (count > 0) {
 1134                 if (getnewvnode_wait(0) == 0) {
 1135                         count--;
 1136                         td->td_vp_reserv++;
 1137                         atomic_add_long(&numvnodes, 1);
 1138                 }
 1139         }
 1140         mtx_unlock(&vnode_free_list_mtx);
 1141 }
 1142 
 1143 void
 1144 getnewvnode_drop_reserve(void)
 1145 {
 1146         struct thread *td;
 1147 
 1148         td = curthread;
 1149         atomic_subtract_long(&numvnodes, td->td_vp_reserv);
 1150         td->td_vp_reserv = 0;
 1151 }
 1152 
 1153 /*
 1154  * Return the next vnode from the free list.
 1155  */
 1156 int
 1157 getnewvnode(const char *tag, struct mount *mp, struct vop_vector *vops,
 1158     struct vnode **vpp)
 1159 {
 1160         struct vnode *vp;
 1161         struct thread *td;
 1162         struct lock_object *lo;
 1163         int error;
 1164 
 1165         CTR3(KTR_VFS, "%s: mp %p with tag %s", __func__, mp, tag);
 1166         vp = NULL;
 1167         td = curthread;
 1168         if (td->td_vp_reserv > 0) {
 1169                 td->td_vp_reserv -= 1;
 1170                 goto alloc;
 1171         }
 1172         mtx_lock(&vnode_free_list_mtx);
 1173         /*
 1174          * Lend our context to reclaim vnodes if they've exceeded the max.
 1175          */
 1176         if (freevnodes > wantfreevnodes)
 1177                 vnlru_free(1);
 1178         error = getnewvnode_wait(mp != NULL && (mp->mnt_kern_flag &
 1179             MNTK_SUSPEND));
 1180 #if 0   /* XXX Not all VFS_VGET/ffs_vget callers check returns. */
 1181         if (error != 0) {
 1182                 mtx_unlock(&vnode_free_list_mtx);
 1183                 return (error);
 1184         }
 1185 #endif
 1186         atomic_add_long(&numvnodes, 1);
 1187         mtx_unlock(&vnode_free_list_mtx);
 1188 alloc:
 1189         atomic_add_long(&vnodes_created, 1);
 1190         vp = (struct vnode *) uma_zalloc(vnode_zone, M_WAITOK);
 1191         /*
 1192          * Locks are given the generic name "vnode" when created.
 1193          * Follow the historic practice of using the filesystem
 1194          * name when they allocated, e.g., "zfs", "ufs", "nfs, etc.
 1195          *
 1196          * Locks live in a witness group keyed on their name. Thus,
 1197          * when a lock is renamed, it must also move from the witness
 1198          * group of its old name to the witness group of its new name.
 1199          *
 1200          * The change only needs to be made when the vnode moves
 1201          * from one filesystem type to another. We ensure that each
 1202          * filesystem use a single static name pointer for its tag so
 1203          * that we can compare pointers rather than doing a strcmp().
 1204          */
 1205         lo = &vp->v_vnlock->lock_object;
 1206         if (lo->lo_name != tag) {
 1207                 lo->lo_name = tag;
 1208                 WITNESS_DESTROY(lo);
 1209                 WITNESS_INIT(lo, tag);
 1210         }
 1211         /*
 1212          * By default, don't allow shared locks unless filesystems opt-in.
 1213          */
 1214         vp->v_vnlock->lock_object.lo_flags |= LK_NOSHARE;
 1215         /*
 1216          * Finalize various vnode identity bits.
 1217          */
 1218         KASSERT(vp->v_object == NULL, ("stale v_object %p", vp));
 1219         KASSERT(vp->v_lockf == NULL, ("stale v_lockf %p", vp));
 1220         KASSERT(vp->v_pollinfo == NULL, ("stale v_pollinfo %p", vp));
 1221         vp->v_type = VNON;
 1222         vp->v_tag = tag;
 1223         vp->v_op = vops;
 1224         v_incr_usecount(vp);
 1225         vp->v_bufobj.bo_ops = &buf_ops_bio;
 1226 #ifdef MAC
 1227         mac_vnode_init(vp);
 1228         if (mp != NULL && (mp->mnt_flag & MNT_MULTILABEL) == 0)
 1229                 mac_vnode_associate_singlelabel(mp, vp);
 1230         else if (mp == NULL && vops != &dead_vnodeops)
 1231                 printf("NULL mp in getnewvnode()\n");
 1232 #endif
 1233         if (mp != NULL) {
 1234                 vp->v_bufobj.bo_bsize = mp->mnt_stat.f_iosize;
 1235                 if ((mp->mnt_kern_flag & MNTK_NOKNOTE) != 0)
 1236                         vp->v_vflag |= VV_NOKNOTE;
 1237         }
 1238 
 1239         /*
 1240          * For the filesystems which do not use vfs_hash_insert(),
 1241          * still initialize v_hash to have vfs_hash_index() useful.
 1242          * E.g., nullfs uses vfs_hash_index() on the lower vnode for
 1243          * its own hashing.
 1244          */
 1245         vp->v_hash = (uintptr_t)vp >> vnsz2log;
 1246 
 1247         *vpp = vp;
 1248         return (0);
 1249 }
 1250 
 1251 /*
 1252  * Delete from old mount point vnode list, if on one.
 1253  */
 1254 static void
 1255 delmntque(struct vnode *vp)
 1256 {
 1257         struct mount *mp;
 1258         int active;
 1259 
 1260         mp = vp->v_mount;
 1261         if (mp == NULL)
 1262                 return;
 1263         MNT_ILOCK(mp);
 1264         VI_LOCK(vp);
 1265         KASSERT(mp->mnt_activevnodelistsize <= mp->mnt_nvnodelistsize,
 1266             ("Active vnode list size %d > Vnode list size %d",
 1267              mp->mnt_activevnodelistsize, mp->mnt_nvnodelistsize));
 1268         active = vp->v_iflag & VI_ACTIVE;
 1269         vp->v_iflag &= ~VI_ACTIVE;
 1270         if (active) {
 1271                 mtx_lock(&vnode_free_list_mtx);
 1272                 TAILQ_REMOVE(&mp->mnt_activevnodelist, vp, v_actfreelist);
 1273                 mp->mnt_activevnodelistsize--;
 1274                 mtx_unlock(&vnode_free_list_mtx);
 1275         }
 1276         vp->v_mount = NULL;
 1277         VI_UNLOCK(vp);
 1278         VNASSERT(mp->mnt_nvnodelistsize > 0, vp,
 1279                 ("bad mount point vnode list size"));
 1280         TAILQ_REMOVE(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
 1281         mp->mnt_nvnodelistsize--;
 1282         MNT_REL(mp);
 1283         MNT_IUNLOCK(mp);
 1284 }
 1285 
 1286 static void
 1287 insmntque_stddtr(struct vnode *vp, void *dtr_arg)
 1288 {
 1289 
 1290         vp->v_data = NULL;
 1291         vp->v_op = &dead_vnodeops;
 1292         vgone(vp);
 1293         vput(vp);
 1294 }
 1295 
 1296 /*
 1297  * Insert into list of vnodes for the new mount point, if available.
 1298  */
 1299 int
 1300 insmntque1(struct vnode *vp, struct mount *mp,
 1301         void (*dtr)(struct vnode *, void *), void *dtr_arg)
 1302 {
 1303 
 1304         KASSERT(vp->v_mount == NULL,
 1305                 ("insmntque: vnode already on per mount vnode list"));
 1306         VNASSERT(mp != NULL, vp, ("Don't call insmntque(foo, NULL)"));
 1307         ASSERT_VOP_ELOCKED(vp, "insmntque: non-locked vp");
 1308 
 1309         /*
 1310          * We acquire the vnode interlock early to ensure that the
 1311          * vnode cannot be recycled by another process releasing a
 1312          * holdcnt on it before we get it on both the vnode list
 1313          * and the active vnode list. The mount mutex protects only
 1314          * manipulation of the vnode list and the vnode freelist
 1315          * mutex protects only manipulation of the active vnode list.
 1316          * Hence the need to hold the vnode interlock throughout.
 1317          */
 1318         MNT_ILOCK(mp);
 1319         VI_LOCK(vp);
 1320         if (((mp->mnt_kern_flag & MNTK_NOINSMNTQ) != 0 &&
 1321             ((mp->mnt_kern_flag & MNTK_UNMOUNTF) != 0 ||
 1322             mp->mnt_nvnodelistsize == 0)) &&
 1323             (vp->v_vflag & VV_FORCEINSMQ) == 0) {
 1324                 VI_UNLOCK(vp);
 1325                 MNT_IUNLOCK(mp);
 1326                 if (dtr != NULL)
 1327                         dtr(vp, dtr_arg);
 1328                 return (EBUSY);
 1329         }
 1330         vp->v_mount = mp;
 1331         MNT_REF(mp);
 1332         TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
 1333         VNASSERT(mp->mnt_nvnodelistsize >= 0, vp,
 1334                 ("neg mount point vnode list size"));
 1335         mp->mnt_nvnodelistsize++;
 1336         KASSERT((vp->v_iflag & VI_ACTIVE) == 0,
 1337             ("Activating already active vnode"));
 1338         vp->v_iflag |= VI_ACTIVE;
 1339         mtx_lock(&vnode_free_list_mtx);
 1340         TAILQ_INSERT_HEAD(&mp->mnt_activevnodelist, vp, v_actfreelist);
 1341         mp->mnt_activevnodelistsize++;
 1342         mtx_unlock(&vnode_free_list_mtx);
 1343         VI_UNLOCK(vp);
 1344         MNT_IUNLOCK(mp);
 1345         return (0);
 1346 }
 1347 
 1348 int
 1349 insmntque(struct vnode *vp, struct mount *mp)
 1350 {
 1351 
 1352         return (insmntque1(vp, mp, insmntque_stddtr, NULL));
 1353 }
 1354 
 1355 /*
 1356  * Flush out and invalidate all buffers associated with a bufobj
 1357  * Called with the underlying object locked.
 1358  */
 1359 int
 1360 bufobj_invalbuf(struct bufobj *bo, int flags, int slpflag, int slptimeo)
 1361 {
 1362         int error;
 1363 
 1364         BO_LOCK(bo);
 1365         if (flags & V_SAVE) {
 1366                 error = bufobj_wwait(bo, slpflag, slptimeo);
 1367                 if (error) {
 1368                         BO_UNLOCK(bo);
 1369                         return (error);
 1370                 }
 1371                 if (bo->bo_dirty.bv_cnt > 0) {
 1372                         BO_UNLOCK(bo);
 1373                         if ((error = BO_SYNC(bo, MNT_WAIT)) != 0)
 1374                                 return (error);
 1375                         /*
 1376                          * XXX We could save a lock/unlock if this was only
 1377                          * enabled under INVARIANTS
 1378                          */
 1379                         BO_LOCK(bo);
 1380                         if (bo->bo_numoutput > 0 || bo->bo_dirty.bv_cnt > 0)
 1381                                 panic("vinvalbuf: dirty bufs");
 1382                 }
 1383         }
 1384         /*
 1385          * If you alter this loop please notice that interlock is dropped and
 1386          * reacquired in flushbuflist.  Special care is needed to ensure that
 1387          * no race conditions occur from this.
 1388          */
 1389         do {
 1390                 error = flushbuflist(&bo->bo_clean,
 1391                     flags, bo, slpflag, slptimeo);
 1392                 if (error == 0 && !(flags & V_CLEANONLY))
 1393                         error = flushbuflist(&bo->bo_dirty,
 1394                             flags, bo, slpflag, slptimeo);
 1395                 if (error != 0 && error != EAGAIN) {
 1396                         BO_UNLOCK(bo);
 1397                         return (error);
 1398                 }
 1399         } while (error != 0);
 1400 
 1401         /*
 1402          * Wait for I/O to complete.  XXX needs cleaning up.  The vnode can
 1403          * have write I/O in-progress but if there is a VM object then the
 1404          * VM object can also have read-I/O in-progress.
 1405          */
 1406         do {
 1407                 bufobj_wwait(bo, 0, 0);
 1408                 BO_UNLOCK(bo);
 1409                 if (bo->bo_object != NULL) {
 1410                         VM_OBJECT_WLOCK(bo->bo_object);
 1411                         vm_object_pip_wait(bo->bo_object, "bovlbx");
 1412                         VM_OBJECT_WUNLOCK(bo->bo_object);
 1413                 }
 1414                 BO_LOCK(bo);
 1415         } while (bo->bo_numoutput > 0);
 1416         BO_UNLOCK(bo);
 1417 
 1418         /*
 1419          * Destroy the copy in the VM cache, too.
 1420          */
 1421         if (bo->bo_object != NULL &&
 1422             (flags & (V_ALT | V_NORMAL | V_CLEANONLY)) == 0) {
 1423                 VM_OBJECT_WLOCK(bo->bo_object);
 1424                 vm_object_page_remove(bo->bo_object, 0, 0, (flags & V_SAVE) ?
 1425                     OBJPR_CLEANONLY : 0);
 1426                 VM_OBJECT_WUNLOCK(bo->bo_object);
 1427         }
 1428 
 1429 #ifdef INVARIANTS
 1430         BO_LOCK(bo);
 1431         if ((flags & (V_ALT | V_NORMAL | V_CLEANONLY)) == 0 &&
 1432             (bo->bo_dirty.bv_cnt > 0 || bo->bo_clean.bv_cnt > 0))
 1433                 panic("vinvalbuf: flush failed");
 1434         BO_UNLOCK(bo);
 1435 #endif
 1436         return (0);
 1437 }
 1438 
 1439 /*
 1440  * Flush out and invalidate all buffers associated with a vnode.
 1441  * Called with the underlying object locked.
 1442  */
 1443 int
 1444 vinvalbuf(struct vnode *vp, int flags, int slpflag, int slptimeo)
 1445 {
 1446 
 1447         CTR3(KTR_VFS, "%s: vp %p with flags %d", __func__, vp, flags);
 1448         ASSERT_VOP_LOCKED(vp, "vinvalbuf");
 1449         if (vp->v_object != NULL && vp->v_object->handle != vp)
 1450                 return (0);
 1451         return (bufobj_invalbuf(&vp->v_bufobj, flags, slpflag, slptimeo));
 1452 }
 1453 
 1454 /*
 1455  * Flush out buffers on the specified list.
 1456  *
 1457  */
 1458 static int
 1459 flushbuflist(struct bufv *bufv, int flags, struct bufobj *bo, int slpflag,
 1460     int slptimeo)
 1461 {
 1462         struct buf *bp, *nbp;
 1463         int retval, error;
 1464         daddr_t lblkno;
 1465         b_xflags_t xflags;
 1466 
 1467         ASSERT_BO_WLOCKED(bo);
 1468 
 1469         retval = 0;
 1470         TAILQ_FOREACH_SAFE(bp, &bufv->bv_hd, b_bobufs, nbp) {
 1471                 if (((flags & V_NORMAL) && (bp->b_xflags & BX_ALTDATA)) ||
 1472                     ((flags & V_ALT) && (bp->b_xflags & BX_ALTDATA) == 0)) {
 1473                         continue;
 1474                 }
 1475                 lblkno = 0;
 1476                 xflags = 0;
 1477                 if (nbp != NULL) {
 1478                         lblkno = nbp->b_lblkno;
 1479                         xflags = nbp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN);
 1480                 }
 1481                 retval = EAGAIN;
 1482                 error = BUF_TIMELOCK(bp,
 1483                     LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK, BO_LOCKPTR(bo),
 1484                     "flushbuf", slpflag, slptimeo);
 1485                 if (error) {
 1486                         BO_LOCK(bo);
 1487                         return (error != ENOLCK ? error : EAGAIN);
 1488                 }
 1489                 KASSERT(bp->b_bufobj == bo,
 1490                     ("bp %p wrong b_bufobj %p should be %p",
 1491                     bp, bp->b_bufobj, bo));
 1492                 if (bp->b_bufobj != bo) {       /* XXX: necessary ? */
 1493                         BUF_UNLOCK(bp);
 1494                         BO_LOCK(bo);
 1495                         return (EAGAIN);
 1496                 }
 1497                 /*
 1498                  * XXX Since there are no node locks for NFS, I
 1499                  * believe there is a slight chance that a delayed
 1500                  * write will occur while sleeping just above, so
 1501                  * check for it.
 1502                  */
 1503                 if (((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) &&
 1504                     (flags & V_SAVE)) {
 1505                         bremfree(bp);
 1506                         bp->b_flags |= B_ASYNC;
 1507                         bwrite(bp);
 1508                         BO_LOCK(bo);
 1509                         return (EAGAIN);        /* XXX: why not loop ? */
 1510                 }
 1511                 bremfree(bp);
 1512                 bp->b_flags |= (B_INVAL | B_RELBUF);
 1513                 bp->b_flags &= ~B_ASYNC;
 1514                 brelse(bp);
 1515                 BO_LOCK(bo);
 1516                 if (nbp != NULL &&
 1517                     (nbp->b_bufobj != bo ||
 1518                      nbp->b_lblkno != lblkno ||
 1519                      (nbp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) != xflags))
 1520                         break;                  /* nbp invalid */
 1521         }
 1522         return (retval);
 1523 }
 1524 
 1525 /*
 1526  * Truncate a file's buffer and pages to a specified length.  This
 1527  * is in lieu of the old vinvalbuf mechanism, which performed unneeded
 1528  * sync activity.
 1529  */
 1530 int
 1531 vtruncbuf(struct vnode *vp, struct ucred *cred, off_t length, int blksize)
 1532 {
 1533         struct buf *bp, *nbp;
 1534         int anyfreed;
 1535         int trunclbn;
 1536         struct bufobj *bo;
 1537 
 1538         CTR5(KTR_VFS, "%s: vp %p with cred %p and block %d:%ju", __func__,
 1539             vp, cred, blksize, (uintmax_t)length);
 1540 
 1541         /*
 1542          * Round up to the *next* lbn.
 1543          */
 1544         trunclbn = (length + blksize - 1) / blksize;
 1545 
 1546         ASSERT_VOP_LOCKED(vp, "vtruncbuf");
 1547 restart:
 1548         bo = &vp->v_bufobj;
 1549         BO_LOCK(bo);
 1550         anyfreed = 1;
 1551         for (;anyfreed;) {
 1552                 anyfreed = 0;
 1553                 TAILQ_FOREACH_SAFE(bp, &bo->bo_clean.bv_hd, b_bobufs, nbp) {
 1554                         if (bp->b_lblkno < trunclbn)
 1555                                 continue;
 1556                         if (BUF_LOCK(bp,
 1557                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1558                             BO_LOCKPTR(bo)) == ENOLCK)
 1559                                 goto restart;
 1560 
 1561                         bremfree(bp);
 1562                         bp->b_flags |= (B_INVAL | B_RELBUF);
 1563                         bp->b_flags &= ~B_ASYNC;
 1564                         brelse(bp);
 1565                         anyfreed = 1;
 1566 
 1567                         BO_LOCK(bo);
 1568                         if (nbp != NULL &&
 1569                             (((nbp->b_xflags & BX_VNCLEAN) == 0) ||
 1570                             (nbp->b_vp != vp) ||
 1571                             (nbp->b_flags & B_DELWRI))) {
 1572                                 BO_UNLOCK(bo);
 1573                                 goto restart;
 1574                         }
 1575                 }
 1576 
 1577                 TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
 1578                         if (bp->b_lblkno < trunclbn)
 1579                                 continue;
 1580                         if (BUF_LOCK(bp,
 1581                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1582                             BO_LOCKPTR(bo)) == ENOLCK)
 1583                                 goto restart;
 1584                         bremfree(bp);
 1585                         bp->b_flags |= (B_INVAL | B_RELBUF);
 1586                         bp->b_flags &= ~B_ASYNC;
 1587                         brelse(bp);
 1588                         anyfreed = 1;
 1589 
 1590                         BO_LOCK(bo);
 1591                         if (nbp != NULL &&
 1592                             (((nbp->b_xflags & BX_VNDIRTY) == 0) ||
 1593                             (nbp->b_vp != vp) ||
 1594                             (nbp->b_flags & B_DELWRI) == 0)) {
 1595                                 BO_UNLOCK(bo);
 1596                                 goto restart;
 1597                         }
 1598                 }
 1599         }
 1600 
 1601         if (length > 0) {
 1602 restartsync:
 1603                 TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
 1604                         if (bp->b_lblkno > 0)
 1605                                 continue;
 1606                         /*
 1607                          * Since we hold the vnode lock this should only
 1608                          * fail if we're racing with the buf daemon.
 1609                          */
 1610                         if (BUF_LOCK(bp,
 1611                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1612                             BO_LOCKPTR(bo)) == ENOLCK) {
 1613                                 goto restart;
 1614                         }
 1615                         VNASSERT((bp->b_flags & B_DELWRI), vp,
 1616                             ("buf(%p) on dirty queue without DELWRI", bp));
 1617 
 1618                         bremfree(bp);
 1619                         bawrite(bp);
 1620                         BO_LOCK(bo);
 1621                         goto restartsync;
 1622                 }
 1623         }
 1624 
 1625         bufobj_wwait(bo, 0, 0);
 1626         BO_UNLOCK(bo);
 1627         vnode_pager_setsize(vp, length);
 1628 
 1629         return (0);
 1630 }
 1631 
 1632 static void
 1633 buf_vlist_remove(struct buf *bp)
 1634 {
 1635         struct bufv *bv;
 1636 
 1637         KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
 1638         ASSERT_BO_WLOCKED(bp->b_bufobj);
 1639         KASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) !=
 1640             (BX_VNDIRTY|BX_VNCLEAN),
 1641             ("buf_vlist_remove: Buf %p is on two lists", bp));
 1642         if (bp->b_xflags & BX_VNDIRTY)
 1643                 bv = &bp->b_bufobj->bo_dirty;
 1644         else
 1645                 bv = &bp->b_bufobj->bo_clean;
 1646         BUF_PCTRIE_REMOVE(&bv->bv_root, bp->b_lblkno);
 1647         TAILQ_REMOVE(&bv->bv_hd, bp, b_bobufs);
 1648         bv->bv_cnt--;
 1649         bp->b_xflags &= ~(BX_VNDIRTY | BX_VNCLEAN);
 1650 }
 1651 
 1652 /*
 1653  * Add the buffer to the sorted clean or dirty block list.
 1654  *
 1655  * NOTE: xflags is passed as a constant, optimizing this inline function!
 1656  */
 1657 static void
 1658 buf_vlist_add(struct buf *bp, struct bufobj *bo, b_xflags_t xflags)
 1659 {
 1660         struct bufv *bv;
 1661         struct buf *n;
 1662         int error;
 1663 
 1664         ASSERT_BO_WLOCKED(bo);
 1665         KASSERT((xflags & BX_VNDIRTY) == 0 || (bo->bo_flag & BO_DEAD) == 0,
 1666             ("dead bo %p", bo));
 1667         KASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) == 0,
 1668             ("buf_vlist_add: Buf %p has existing xflags %d", bp, bp->b_xflags));
 1669         bp->b_xflags |= xflags;
 1670         if (xflags & BX_VNDIRTY)
 1671                 bv = &bo->bo_dirty;
 1672         else
 1673                 bv = &bo->bo_clean;
 1674 
 1675         /*
 1676          * Keep the list ordered.  Optimize empty list insertion.  Assume
 1677          * we tend to grow at the tail so lookup_le should usually be cheaper
 1678          * than _ge. 
 1679          */
 1680         if (bv->bv_cnt == 0 ||
 1681             bp->b_lblkno > TAILQ_LAST(&bv->bv_hd, buflists)->b_lblkno)
 1682                 TAILQ_INSERT_TAIL(&bv->bv_hd, bp, b_bobufs);
 1683         else if ((n = BUF_PCTRIE_LOOKUP_LE(&bv->bv_root, bp->b_lblkno)) == NULL)
 1684                 TAILQ_INSERT_HEAD(&bv->bv_hd, bp, b_bobufs);
 1685         else
 1686                 TAILQ_INSERT_AFTER(&bv->bv_hd, n, bp, b_bobufs);
 1687         error = BUF_PCTRIE_INSERT(&bv->bv_root, bp);
 1688         if (error)
 1689                 panic("buf_vlist_add:  Preallocated nodes insufficient.");
 1690         bv->bv_cnt++;
 1691 }
 1692 
 1693 /*
 1694  * Lookup a buffer using the splay tree.  Note that we specifically avoid
 1695  * shadow buffers used in background bitmap writes.
 1696  *
 1697  * This code isn't quite efficient as it could be because we are maintaining
 1698  * two sorted lists and do not know which list the block resides in.
 1699  *
 1700  * During a "make buildworld" the desired buffer is found at one of
 1701  * the roots more than 60% of the time.  Thus, checking both roots
 1702  * before performing either splay eliminates unnecessary splays on the
 1703  * first tree splayed.
 1704  */
 1705 struct buf *
 1706 gbincore(struct bufobj *bo, daddr_t lblkno)
 1707 {
 1708         struct buf *bp;
 1709 
 1710         ASSERT_BO_LOCKED(bo);
 1711         bp = BUF_PCTRIE_LOOKUP(&bo->bo_clean.bv_root, lblkno);
 1712         if (bp != NULL)
 1713                 return (bp);
 1714         return BUF_PCTRIE_LOOKUP(&bo->bo_dirty.bv_root, lblkno);
 1715 }
 1716 
 1717 /*
 1718  * Associate a buffer with a vnode.
 1719  */
 1720 void
 1721 bgetvp(struct vnode *vp, struct buf *bp)
 1722 {
 1723         struct bufobj *bo;
 1724 
 1725         bo = &vp->v_bufobj;
 1726         ASSERT_BO_WLOCKED(bo);
 1727         VNASSERT(bp->b_vp == NULL, bp->b_vp, ("bgetvp: not free"));
 1728 
 1729         CTR3(KTR_BUF, "bgetvp(%p) vp %p flags %X", bp, vp, bp->b_flags);
 1730         VNASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) == 0, vp,
 1731             ("bgetvp: bp already attached! %p", bp));
 1732 
 1733         vhold(vp);
 1734         bp->b_vp = vp;
 1735         bp->b_bufobj = bo;
 1736         /*
 1737          * Insert onto list for new vnode.
 1738          */
 1739         buf_vlist_add(bp, bo, BX_VNCLEAN);
 1740 }
 1741 
 1742 /*
 1743  * Disassociate a buffer from a vnode.
 1744  */
 1745 void
 1746 brelvp(struct buf *bp)
 1747 {
 1748         struct bufobj *bo;
 1749         struct vnode *vp;
 1750 
 1751         CTR3(KTR_BUF, "brelvp(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
 1752         KASSERT(bp->b_vp != NULL, ("brelvp: NULL"));
 1753 
 1754         /*
 1755          * Delete from old vnode list, if on one.
 1756          */
 1757         vp = bp->b_vp;          /* XXX */
 1758         bo = bp->b_bufobj;
 1759         BO_LOCK(bo);
 1760         if (bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN))
 1761                 buf_vlist_remove(bp);
 1762         else
 1763                 panic("brelvp: Buffer %p not on queue.", bp);
 1764         if ((bo->bo_flag & BO_ONWORKLST) && bo->bo_dirty.bv_cnt == 0) {
 1765                 bo->bo_flag &= ~BO_ONWORKLST;
 1766                 mtx_lock(&sync_mtx);
 1767                 LIST_REMOVE(bo, bo_synclist);
 1768                 syncer_worklist_len--;
 1769                 mtx_unlock(&sync_mtx);
 1770         }
 1771         bp->b_vp = NULL;
 1772         bp->b_bufobj = NULL;
 1773         BO_UNLOCK(bo);
 1774         vdrop(vp);
 1775 }
 1776 
 1777 /*
 1778  * Add an item to the syncer work queue.
 1779  */
 1780 static void
 1781 vn_syncer_add_to_worklist(struct bufobj *bo, int delay)
 1782 {
 1783         int slot;
 1784 
 1785         ASSERT_BO_WLOCKED(bo);
 1786 
 1787         mtx_lock(&sync_mtx);
 1788         if (bo->bo_flag & BO_ONWORKLST)
 1789                 LIST_REMOVE(bo, bo_synclist);
 1790         else {
 1791                 bo->bo_flag |= BO_ONWORKLST;
 1792                 syncer_worklist_len++;
 1793         }
 1794 
 1795         if (delay > syncer_maxdelay - 2)
 1796                 delay = syncer_maxdelay - 2;
 1797         slot = (syncer_delayno + delay) & syncer_mask;
 1798 
 1799         LIST_INSERT_HEAD(&syncer_workitem_pending[slot], bo, bo_synclist);
 1800         mtx_unlock(&sync_mtx);
 1801 }
 1802 
 1803 static int
 1804 sysctl_vfs_worklist_len(SYSCTL_HANDLER_ARGS)
 1805 {
 1806         int error, len;
 1807 
 1808         mtx_lock(&sync_mtx);
 1809         len = syncer_worklist_len - sync_vnode_count;
 1810         mtx_unlock(&sync_mtx);
 1811         error = SYSCTL_OUT(req, &len, sizeof(len));
 1812         return (error);
 1813 }
 1814 
 1815 SYSCTL_PROC(_vfs, OID_AUTO, worklist_len, CTLTYPE_INT | CTLFLAG_RD, NULL, 0,
 1816     sysctl_vfs_worklist_len, "I", "Syncer thread worklist length");
 1817 
 1818 static struct proc *updateproc;
 1819 static void sched_sync(void);
 1820 static struct kproc_desc up_kp = {
 1821         "syncer",
 1822         sched_sync,
 1823         &updateproc
 1824 };
 1825 SYSINIT(syncer, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &up_kp);
 1826 
 1827 static int
 1828 sync_vnode(struct synclist *slp, struct bufobj **bo, struct thread *td)
 1829 {
 1830         struct vnode *vp;
 1831         struct mount *mp;
 1832 
 1833         *bo = LIST_FIRST(slp);
 1834         if (*bo == NULL)
 1835                 return (0);
 1836         vp = (*bo)->__bo_vnode; /* XXX */
 1837         if (VOP_ISLOCKED(vp) != 0 || VI_TRYLOCK(vp) == 0)
 1838                 return (1);
 1839         /*
 1840          * We use vhold in case the vnode does not
 1841          * successfully sync.  vhold prevents the vnode from
 1842          * going away when we unlock the sync_mtx so that
 1843          * we can acquire the vnode interlock.
 1844          */
 1845         vholdl(vp);
 1846         mtx_unlock(&sync_mtx);
 1847         VI_UNLOCK(vp);
 1848         if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
 1849                 vdrop(vp);
 1850                 mtx_lock(&sync_mtx);
 1851                 return (*bo == LIST_FIRST(slp));
 1852         }
 1853         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 1854         (void) VOP_FSYNC(vp, MNT_LAZY, td);
 1855         VOP_UNLOCK(vp, 0);
 1856         vn_finished_write(mp);
 1857         BO_LOCK(*bo);
 1858         if (((*bo)->bo_flag & BO_ONWORKLST) != 0) {
 1859                 /*
 1860                  * Put us back on the worklist.  The worklist
 1861                  * routine will remove us from our current
 1862                  * position and then add us back in at a later
 1863                  * position.
 1864                  */
 1865                 vn_syncer_add_to_worklist(*bo, syncdelay);
 1866         }
 1867         BO_UNLOCK(*bo);
 1868         vdrop(vp);
 1869         mtx_lock(&sync_mtx);
 1870         return (0);
 1871 }
 1872 
 1873 static int first_printf = 1;
 1874 
 1875 /*
 1876  * System filesystem synchronizer daemon.
 1877  */
 1878 static void
 1879 sched_sync(void)
 1880 {
 1881         struct synclist *next, *slp;
 1882         struct bufobj *bo;
 1883         long starttime;
 1884         struct thread *td = curthread;
 1885         int last_work_seen;
 1886         int net_worklist_len;
 1887         int syncer_final_iter;
 1888         int error;
 1889 
 1890         last_work_seen = 0;
 1891         syncer_final_iter = 0;
 1892         syncer_state = SYNCER_RUNNING;
 1893         starttime = time_uptime;
 1894         td->td_pflags |= TDP_NORUNNINGBUF;
 1895 
 1896         EVENTHANDLER_REGISTER(shutdown_pre_sync, syncer_shutdown, td->td_proc,
 1897             SHUTDOWN_PRI_LAST);
 1898 
 1899         mtx_lock(&sync_mtx);
 1900         for (;;) {
 1901                 if (syncer_state == SYNCER_FINAL_DELAY &&
 1902                     syncer_final_iter == 0) {
 1903                         mtx_unlock(&sync_mtx);
 1904                         kproc_suspend_check(td->td_proc);
 1905                         mtx_lock(&sync_mtx);
 1906                 }
 1907                 net_worklist_len = syncer_worklist_len - sync_vnode_count;
 1908                 if (syncer_state != SYNCER_RUNNING &&
 1909                     starttime != time_uptime) {
 1910                         if (first_printf) {
 1911                                 printf("\nSyncing disks, vnodes remaining...");
 1912                                 first_printf = 0;
 1913                         }
 1914                         printf("%d ", net_worklist_len);
 1915                 }
 1916                 starttime = time_uptime;
 1917 
 1918                 /*
 1919                  * Push files whose dirty time has expired.  Be careful
 1920                  * of interrupt race on slp queue.
 1921                  *
 1922                  * Skip over empty worklist slots when shutting down.
 1923                  */
 1924                 do {
 1925                         slp = &syncer_workitem_pending[syncer_delayno];
 1926                         syncer_delayno += 1;
 1927                         if (syncer_delayno == syncer_maxdelay)
 1928                                 syncer_delayno = 0;
 1929                         next = &syncer_workitem_pending[syncer_delayno];
 1930                         /*
 1931                          * If the worklist has wrapped since the
 1932                          * it was emptied of all but syncer vnodes,
 1933                          * switch to the FINAL_DELAY state and run
 1934                          * for one more second.
 1935                          */
 1936                         if (syncer_state == SYNCER_SHUTTING_DOWN &&
 1937                             net_worklist_len == 0 &&
 1938                             last_work_seen == syncer_delayno) {
 1939                                 syncer_state = SYNCER_FINAL_DELAY;
 1940                                 syncer_final_iter = SYNCER_SHUTDOWN_SPEEDUP;
 1941                         }
 1942                 } while (syncer_state != SYNCER_RUNNING && LIST_EMPTY(slp) &&
 1943                     syncer_worklist_len > 0);
 1944 
 1945                 /*
 1946                  * Keep track of the last time there was anything
 1947                  * on the worklist other than syncer vnodes.
 1948                  * Return to the SHUTTING_DOWN state if any
 1949                  * new work appears.
 1950                  */
 1951                 if (net_worklist_len > 0 || syncer_state == SYNCER_RUNNING)
 1952                         last_work_seen = syncer_delayno;
 1953                 if (net_worklist_len > 0 && syncer_state == SYNCER_FINAL_DELAY)
 1954                         syncer_state = SYNCER_SHUTTING_DOWN;
 1955                 while (!LIST_EMPTY(slp)) {
 1956                         error = sync_vnode(slp, &bo, td);
 1957                         if (error == 1) {
 1958                                 LIST_REMOVE(bo, bo_synclist);
 1959                                 LIST_INSERT_HEAD(next, bo, bo_synclist);
 1960                                 continue;
 1961                         }
 1962 
 1963                         if (first_printf == 0)
 1964                                 wdog_kern_pat(WD_LASTVAL);
 1965 
 1966                 }
 1967                 if (syncer_state == SYNCER_FINAL_DELAY && syncer_final_iter > 0)
 1968                         syncer_final_iter--;
 1969                 /*
 1970                  * The variable rushjob allows the kernel to speed up the
 1971                  * processing of the filesystem syncer process. A rushjob
 1972                  * value of N tells the filesystem syncer to process the next
 1973                  * N seconds worth of work on its queue ASAP. Currently rushjob
 1974                  * is used by the soft update code to speed up the filesystem
 1975                  * syncer process when the incore state is getting so far
 1976                  * ahead of the disk that the kernel memory pool is being
 1977                  * threatened with exhaustion.
 1978                  */
 1979                 if (rushjob > 0) {
 1980                         rushjob -= 1;
 1981                         continue;
 1982                 }
 1983                 /*
 1984                  * Just sleep for a short period of time between
 1985                  * iterations when shutting down to allow some I/O
 1986                  * to happen.
 1987                  *
 1988                  * If it has taken us less than a second to process the
 1989                  * current work, then wait. Otherwise start right over
 1990                  * again. We can still lose time if any single round
 1991                  * takes more than two seconds, but it does not really
 1992                  * matter as we are just trying to generally pace the
 1993                  * filesystem activity.
 1994                  */
 1995                 if (syncer_state != SYNCER_RUNNING ||
 1996                     time_uptime == starttime) {
 1997                         thread_lock(td);
 1998                         sched_prio(td, PPAUSE);
 1999                         thread_unlock(td);
 2000                 }
 2001                 if (syncer_state != SYNCER_RUNNING)
 2002                         cv_timedwait(&sync_wakeup, &sync_mtx,
 2003                             hz / SYNCER_SHUTDOWN_SPEEDUP);
 2004                 else if (time_uptime == starttime)
 2005                         cv_timedwait(&sync_wakeup, &sync_mtx, hz);
 2006         }
 2007 }
 2008 
 2009 /*
 2010  * Request the syncer daemon to speed up its work.
 2011  * We never push it to speed up more than half of its
 2012  * normal turn time, otherwise it could take over the cpu.
 2013  */
 2014 int
 2015 speedup_syncer(void)
 2016 {
 2017         int ret = 0;
 2018 
 2019         mtx_lock(&sync_mtx);
 2020         if (rushjob < syncdelay / 2) {
 2021                 rushjob += 1;
 2022                 stat_rush_requests += 1;
 2023                 ret = 1;
 2024         }
 2025         mtx_unlock(&sync_mtx);
 2026         cv_broadcast(&sync_wakeup);
 2027         return (ret);
 2028 }
 2029 
 2030 /*
 2031  * Tell the syncer to speed up its work and run though its work
 2032  * list several times, then tell it to shut down.
 2033  */
 2034 static void
 2035 syncer_shutdown(void *arg, int howto)
 2036 {
 2037 
 2038         if (howto & RB_NOSYNC)
 2039                 return;
 2040         mtx_lock(&sync_mtx);
 2041         syncer_state = SYNCER_SHUTTING_DOWN;
 2042         rushjob = 0;
 2043         mtx_unlock(&sync_mtx);
 2044         cv_broadcast(&sync_wakeup);
 2045         kproc_shutdown(arg, howto);
 2046 }
 2047 
 2048 void
 2049 syncer_suspend(void)
 2050 {
 2051 
 2052         syncer_shutdown(updateproc, 0);
 2053 }
 2054 
 2055 void
 2056 syncer_resume(void)
 2057 {
 2058 
 2059         mtx_lock(&sync_mtx);
 2060         first_printf = 1;
 2061         syncer_state = SYNCER_RUNNING;
 2062         mtx_unlock(&sync_mtx);
 2063         cv_broadcast(&sync_wakeup);
 2064         kproc_resume(updateproc);
 2065 }
 2066 
 2067 /*
 2068  * Reassign a buffer from one vnode to another.
 2069  * Used to assign file specific control information
 2070  * (indirect blocks) to the vnode to which they belong.
 2071  */
 2072 void
 2073 reassignbuf(struct buf *bp)
 2074 {
 2075         struct vnode *vp;
 2076         struct bufobj *bo;
 2077         int delay;
 2078 #ifdef INVARIANTS
 2079         struct bufv *bv;
 2080 #endif
 2081 
 2082         vp = bp->b_vp;
 2083         bo = bp->b_bufobj;
 2084         ++reassignbufcalls;
 2085 
 2086         CTR3(KTR_BUF, "reassignbuf(%p) vp %p flags %X",
 2087             bp, bp->b_vp, bp->b_flags);
 2088         /*
 2089          * B_PAGING flagged buffers cannot be reassigned because their vp
 2090          * is not fully linked in.
 2091          */
 2092         if (bp->b_flags & B_PAGING)
 2093                 panic("cannot reassign paging buffer");
 2094 
 2095         /*
 2096          * Delete from old vnode list, if on one.
 2097          */
 2098         BO_LOCK(bo);
 2099         if (bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN))
 2100                 buf_vlist_remove(bp);
 2101         else
 2102                 panic("reassignbuf: Buffer %p not on queue.", bp);
 2103         /*
 2104          * If dirty, put on list of dirty buffers; otherwise insert onto list
 2105          * of clean buffers.
 2106          */
 2107         if (bp->b_flags & B_DELWRI) {
 2108                 if ((bo->bo_flag & BO_ONWORKLST) == 0) {
 2109                         switch (vp->v_type) {
 2110                         case VDIR:
 2111                                 delay = dirdelay;
 2112                                 break;
 2113                         case VCHR:
 2114                                 delay = metadelay;
 2115                                 break;
 2116                         default:
 2117                                 delay = filedelay;
 2118                         }
 2119                         vn_syncer_add_to_worklist(bo, delay);
 2120                 }
 2121                 buf_vlist_add(bp, bo, BX_VNDIRTY);
 2122         } else {
 2123                 buf_vlist_add(bp, bo, BX_VNCLEAN);
 2124 
 2125                 if ((bo->bo_flag & BO_ONWORKLST) && bo->bo_dirty.bv_cnt == 0) {
 2126                         mtx_lock(&sync_mtx);
 2127                         LIST_REMOVE(bo, bo_synclist);
 2128                         syncer_worklist_len--;
 2129                         mtx_unlock(&sync_mtx);
 2130                         bo->bo_flag &= ~BO_ONWORKLST;
 2131                 }
 2132         }
 2133 #ifdef INVARIANTS
 2134         bv = &bo->bo_clean;
 2135         bp = TAILQ_FIRST(&bv->bv_hd);
 2136         KASSERT(bp == NULL || bp->b_bufobj == bo,
 2137             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 2138         bp = TAILQ_LAST(&bv->bv_hd, buflists);
 2139         KASSERT(bp == NULL || bp->b_bufobj == bo,
 2140             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 2141         bv = &bo->bo_dirty;
 2142         bp = TAILQ_FIRST(&bv->bv_hd);
 2143         KASSERT(bp == NULL || bp->b_bufobj == bo,
 2144             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 2145         bp = TAILQ_LAST(&bv->bv_hd, buflists);
 2146         KASSERT(bp == NULL || bp->b_bufobj == bo,
 2147             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 2148 #endif
 2149         BO_UNLOCK(bo);
 2150 }
 2151 
 2152 /*
 2153  * Increment the use and hold counts on the vnode, taking care to reference
 2154  * the driver's usecount if this is a chardev.  The vholdl() will remove
 2155  * the vnode from the free list if it is presently free.  Requires the
 2156  * vnode interlock and returns with it held.
 2157  */
 2158 static void
 2159 v_incr_usecount(struct vnode *vp)
 2160 {
 2161 
 2162         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 2163         vholdl(vp);
 2164         vp->v_usecount++;
 2165         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 2166                 dev_lock();
 2167                 vp->v_rdev->si_usecount++;
 2168                 dev_unlock();
 2169         }
 2170 }
 2171 
 2172 /*
 2173  * Turn a holdcnt into a use+holdcnt such that only one call to
 2174  * v_decr_usecount is needed.
 2175  */
 2176 static void
 2177 v_upgrade_usecount(struct vnode *vp)
 2178 {
 2179 
 2180         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 2181         vp->v_usecount++;
 2182         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 2183                 dev_lock();
 2184                 vp->v_rdev->si_usecount++;
 2185                 dev_unlock();
 2186         }
 2187 }
 2188 
 2189 /*
 2190  * Decrement the vnode use and hold count along with the driver's usecount
 2191  * if this is a chardev.  The vdropl() below releases the vnode interlock
 2192  * as it may free the vnode.
 2193  */
 2194 static void
 2195 v_decr_usecount(struct vnode *vp)
 2196 {
 2197 
 2198         ASSERT_VI_LOCKED(vp, __FUNCTION__);
 2199         VNASSERT(vp->v_usecount > 0, vp,
 2200             ("v_decr_usecount: negative usecount"));
 2201         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 2202         vp->v_usecount--;
 2203         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 2204                 dev_lock();
 2205                 vp->v_rdev->si_usecount--;
 2206                 dev_unlock();
 2207         }
 2208         vdropl(vp);
 2209 }
 2210 
 2211 /*
 2212  * Decrement only the use count and driver use count.  This is intended to
 2213  * be paired with a follow on vdropl() to release the remaining hold count.
 2214  * In this way we may vgone() a vnode with a 0 usecount without risk of
 2215  * having it end up on a free list because the hold count is kept above 0.
 2216  */
 2217 static void
 2218 v_decr_useonly(struct vnode *vp)
 2219 {
 2220 
 2221         ASSERT_VI_LOCKED(vp, __FUNCTION__);
 2222         VNASSERT(vp->v_usecount > 0, vp,
 2223             ("v_decr_useonly: negative usecount"));
 2224         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 2225         vp->v_usecount--;
 2226         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 2227                 dev_lock();
 2228                 vp->v_rdev->si_usecount--;
 2229                 dev_unlock();
 2230         }
 2231 }
 2232 
 2233 /*
 2234  * Grab a particular vnode from the free list, increment its
 2235  * reference count and lock it.  VI_DOOMED is set if the vnode
 2236  * is being destroyed.  Only callers who specify LK_RETRY will
 2237  * see doomed vnodes.  If inactive processing was delayed in
 2238  * vput try to do it here.
 2239  */
 2240 int
 2241 vget(struct vnode *vp, int flags, struct thread *td)
 2242 {
 2243         int error;
 2244 
 2245         error = 0;
 2246         VNASSERT((flags & LK_TYPE_MASK) != 0, vp,
 2247             ("vget: invalid lock operation"));
 2248         CTR3(KTR_VFS, "%s: vp %p with flags %d", __func__, vp, flags);
 2249 
 2250         if ((flags & LK_INTERLOCK) == 0)
 2251                 VI_LOCK(vp);
 2252         vholdl(vp);
 2253         if ((error = vn_lock(vp, flags | LK_INTERLOCK)) != 0) {
 2254                 vdrop(vp);
 2255                 CTR2(KTR_VFS, "%s: impossible to lock vnode %p", __func__,
 2256                     vp);
 2257                 return (error);
 2258         }
 2259         if (vp->v_iflag & VI_DOOMED && (flags & LK_RETRY) == 0)
 2260                 panic("vget: vn_lock failed to return ENOENT\n");
 2261         VI_LOCK(vp);
 2262         /* Upgrade our holdcnt to a usecount. */
 2263         v_upgrade_usecount(vp);
 2264         /*
 2265          * We don't guarantee that any particular close will
 2266          * trigger inactive processing so just make a best effort
 2267          * here at preventing a reference to a removed file.  If
 2268          * we don't succeed no harm is done.
 2269          */
 2270         if (vp->v_iflag & VI_OWEINACT) {
 2271                 if (VOP_ISLOCKED(vp) == LK_EXCLUSIVE &&
 2272                     (flags & LK_NOWAIT) == 0)
 2273                         vinactive(vp, td);
 2274                 vp->v_iflag &= ~VI_OWEINACT;
 2275         }
 2276         VI_UNLOCK(vp);
 2277         return (0);
 2278 }
 2279 
 2280 /*
 2281  * Increase the reference count of a vnode.
 2282  */
 2283 void
 2284 vref(struct vnode *vp)
 2285 {
 2286 
 2287         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 2288         VI_LOCK(vp);
 2289         v_incr_usecount(vp);
 2290         VI_UNLOCK(vp);
 2291 }
 2292 
 2293 /*
 2294  * Return reference count of a vnode.
 2295  *
 2296  * The results of this call are only guaranteed when some mechanism other
 2297  * than the VI lock is used to stop other processes from gaining references
 2298  * to the vnode.  This may be the case if the caller holds the only reference.
 2299  * This is also useful when stale data is acceptable as race conditions may
 2300  * be accounted for by some other means.
 2301  */
 2302 int
 2303 vrefcnt(struct vnode *vp)
 2304 {
 2305         int usecnt;
 2306 
 2307         VI_LOCK(vp);
 2308         usecnt = vp->v_usecount;
 2309         VI_UNLOCK(vp);
 2310 
 2311         return (usecnt);
 2312 }
 2313 
 2314 #define VPUTX_VRELE     1
 2315 #define VPUTX_VPUT      2
 2316 #define VPUTX_VUNREF    3
 2317 
 2318 static void
 2319 vputx(struct vnode *vp, int func)
 2320 {
 2321         int error;
 2322 
 2323         KASSERT(vp != NULL, ("vputx: null vp"));
 2324         if (func == VPUTX_VUNREF)
 2325                 ASSERT_VOP_LOCKED(vp, "vunref");
 2326         else if (func == VPUTX_VPUT)
 2327                 ASSERT_VOP_LOCKED(vp, "vput");
 2328         else
 2329                 KASSERT(func == VPUTX_VRELE, ("vputx: wrong func"));
 2330         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 2331         VI_LOCK(vp);
 2332 
 2333         /* Skip this v_writecount check if we're going to panic below. */
 2334         VNASSERT(vp->v_writecount < vp->v_usecount || vp->v_usecount < 1, vp,
 2335             ("vputx: missed vn_close"));
 2336         error = 0;
 2337 
 2338         if (vp->v_usecount > 1 || ((vp->v_iflag & VI_DOINGINACT) &&
 2339             vp->v_usecount == 1)) {
 2340                 if (func == VPUTX_VPUT)
 2341                         VOP_UNLOCK(vp, 0);
 2342                 v_decr_usecount(vp);
 2343                 return;
 2344         }
 2345 
 2346         if (vp->v_usecount != 1) {
 2347                 vprint("vputx: negative ref count", vp);
 2348                 panic("vputx: negative ref cnt");
 2349         }
 2350         CTR2(KTR_VFS, "%s: return vnode %p to the freelist", __func__, vp);
 2351         /*
 2352          * We want to hold the vnode until the inactive finishes to
 2353          * prevent vgone() races.  We drop the use count here and the
 2354          * hold count below when we're done.
 2355          */
 2356         v_decr_useonly(vp);
 2357         /*
 2358          * We must call VOP_INACTIVE with the node locked. Mark
 2359          * as VI_DOINGINACT to avoid recursion.
 2360          */
 2361         vp->v_iflag |= VI_OWEINACT;
 2362         switch (func) {
 2363         case VPUTX_VRELE:
 2364                 error = vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK);
 2365                 VI_LOCK(vp);
 2366                 break;
 2367         case VPUTX_VPUT:
 2368                 if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE) {
 2369                         error = VOP_LOCK(vp, LK_UPGRADE | LK_INTERLOCK |
 2370                             LK_NOWAIT);
 2371                         VI_LOCK(vp);
 2372                 }
 2373                 break;
 2374         case VPUTX_VUNREF:
 2375                 if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE) {
 2376                         error = VOP_LOCK(vp, LK_TRYUPGRADE | LK_INTERLOCK);
 2377                         VI_LOCK(vp);
 2378                 }
 2379                 break;
 2380         }
 2381         if (vp->v_usecount > 0)
 2382                 vp->v_iflag &= ~VI_OWEINACT;
 2383         if (error == 0) {
 2384                 if (vp->v_iflag & VI_OWEINACT)
 2385                         vinactive(vp, curthread);
 2386                 if (func != VPUTX_VUNREF)
 2387                         VOP_UNLOCK(vp, 0);
 2388         }
 2389         vdropl(vp);
 2390 }
 2391 
 2392 /*
 2393  * Vnode put/release.
 2394  * If count drops to zero, call inactive routine and return to freelist.
 2395  */
 2396 void
 2397 vrele(struct vnode *vp)
 2398 {
 2399 
 2400         vputx(vp, VPUTX_VRELE);
 2401 }
 2402 
 2403 /*
 2404  * Release an already locked vnode.  This give the same effects as
 2405  * unlock+vrele(), but takes less time and avoids releasing and
 2406  * re-aquiring the lock (as vrele() acquires the lock internally.)
 2407  */
 2408 void
 2409 vput(struct vnode *vp)
 2410 {
 2411 
 2412         vputx(vp, VPUTX_VPUT);
 2413 }
 2414 
 2415 /*
 2416  * Release an exclusively locked vnode. Do not unlock the vnode lock.
 2417  */
 2418 void
 2419 vunref(struct vnode *vp)
 2420 {
 2421 
 2422         vputx(vp, VPUTX_VUNREF);
 2423 }
 2424 
 2425 /*
 2426  * Somebody doesn't want the vnode recycled.
 2427  */
 2428 void
 2429 vhold(struct vnode *vp)
 2430 {
 2431 
 2432         VI_LOCK(vp);
 2433         vholdl(vp);
 2434         VI_UNLOCK(vp);
 2435 }
 2436 
 2437 /*
 2438  * Increase the hold count and activate if this is the first reference.
 2439  */
 2440 void
 2441 vholdl(struct vnode *vp)
 2442 {
 2443         struct mount *mp;
 2444 
 2445         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 2446 #ifdef INVARIANTS
 2447         /* getnewvnode() calls v_incr_usecount() without holding interlock. */
 2448         if (vp->v_type != VNON || vp->v_data != NULL)
 2449                 ASSERT_VI_LOCKED(vp, "vholdl");
 2450 #endif
 2451         vp->v_holdcnt++;
 2452         if ((vp->v_iflag & VI_FREE) == 0)
 2453                 return;
 2454         VNASSERT(vp->v_holdcnt == 1, vp, ("vholdl: wrong hold count"));
 2455         VNASSERT(vp->v_op != NULL, vp, ("vholdl: vnode already reclaimed."));
 2456         /*
 2457          * Remove a vnode from the free list, mark it as in use,
 2458          * and put it on the active list.
 2459          */
 2460         mtx_lock(&vnode_free_list_mtx);
 2461         TAILQ_REMOVE(&vnode_free_list, vp, v_actfreelist);
 2462         freevnodes--;
 2463         vp->v_iflag &= ~VI_FREE;
 2464         KASSERT((vp->v_iflag & VI_ACTIVE) == 0,
 2465             ("Activating already active vnode"));
 2466         vp->v_iflag |= VI_ACTIVE;
 2467         mp = vp->v_mount;
 2468         TAILQ_INSERT_HEAD(&mp->mnt_activevnodelist, vp, v_actfreelist);
 2469         mp->mnt_activevnodelistsize++;
 2470         mtx_unlock(&vnode_free_list_mtx);
 2471 }
 2472 
 2473 /*
 2474  * Note that there is one less who cares about this vnode.
 2475  * vdrop() is the opposite of vhold().
 2476  */
 2477 void
 2478 vdrop(struct vnode *vp)
 2479 {
 2480 
 2481         VI_LOCK(vp);
 2482         vdropl(vp);
 2483 }
 2484 
 2485 /*
 2486  * Drop the hold count of the vnode.  If this is the last reference to
 2487  * the vnode we place it on the free list unless it has been vgone'd
 2488  * (marked VI_DOOMED) in which case we will free it.
 2489  *
 2490  * Because the vnode vm object keeps a hold reference on the vnode if
 2491  * there is at least one resident non-cached page, the vnode cannot
 2492  * leave the active list without the page cleanup done.
 2493  */
 2494 void
 2495 vdropl(struct vnode *vp)
 2496 {
 2497         struct bufobj *bo;
 2498         struct mount *mp;
 2499         int active;
 2500 
 2501         ASSERT_VI_LOCKED(vp, "vdropl");
 2502         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 2503         if (vp->v_holdcnt <= 0)
 2504                 panic("vdrop: holdcnt %d", vp->v_holdcnt);
 2505         vp->v_holdcnt--;
 2506         if (vp->v_holdcnt > 0) {
 2507                 VI_UNLOCK(vp);
 2508                 return;
 2509         }
 2510         if ((vp->v_iflag & VI_DOOMED) == 0) {
 2511                 /*
 2512                  * Mark a vnode as free: remove it from its active list
 2513                  * and put it up for recycling on the freelist.
 2514                  */
 2515                 VNASSERT(vp->v_op != NULL, vp,
 2516                     ("vdropl: vnode already reclaimed."));
 2517                 VNASSERT((vp->v_iflag & VI_FREE) == 0, vp,
 2518                     ("vnode already free"));
 2519                 VNASSERT(vp->v_holdcnt == 0, vp,
 2520                     ("vdropl: freeing when we shouldn't"));
 2521                 active = vp->v_iflag & VI_ACTIVE;
 2522                 if ((vp->v_iflag & VI_OWEINACT) == 0) {
 2523                         vp->v_iflag &= ~VI_ACTIVE;
 2524                         mp = vp->v_mount;
 2525                         mtx_lock(&vnode_free_list_mtx);
 2526                         if (active) {
 2527                                 TAILQ_REMOVE(&mp->mnt_activevnodelist, vp,
 2528                                     v_actfreelist);
 2529                                 mp->mnt_activevnodelistsize--;
 2530                         }
 2531                         TAILQ_INSERT_TAIL(&vnode_free_list, vp,
 2532                             v_actfreelist);
 2533                         freevnodes++;
 2534                         vp->v_iflag |= VI_FREE;
 2535                         mtx_unlock(&vnode_free_list_mtx);
 2536                 } else {
 2537                         atomic_add_long(&free_owe_inact, 1);
 2538                 }
 2539                 VI_UNLOCK(vp);
 2540                 return;
 2541         }
 2542         /*
 2543          * The vnode has been marked for destruction, so free it.
 2544          *
 2545          * The vnode will be returned to the zone where it will
 2546          * normally remain until it is needed for another vnode. We
 2547          * need to cleanup (or verify that the cleanup has already
 2548          * been done) any residual data left from its current use
 2549          * so as not to contaminate the freshly allocated vnode.
 2550          */
 2551         CTR2(KTR_VFS, "%s: destroying the vnode %p", __func__, vp);
 2552         atomic_subtract_long(&numvnodes, 1);
 2553         bo = &vp->v_bufobj;
 2554         VNASSERT((vp->v_iflag & VI_FREE) == 0, vp,
 2555             ("cleaned vnode still on the free list."));
 2556         VNASSERT(vp->v_data == NULL, vp, ("cleaned vnode isn't"));
 2557         VNASSERT(vp->v_holdcnt == 0, vp, ("Non-zero hold count"));
 2558         VNASSERT(vp->v_usecount == 0, vp, ("Non-zero use count"));
 2559         VNASSERT(vp->v_writecount == 0, vp, ("Non-zero write count"));
 2560         VNASSERT(bo->bo_numoutput == 0, vp, ("Clean vnode has pending I/O's"));
 2561         VNASSERT(bo->bo_clean.bv_cnt == 0, vp, ("cleanbufcnt not 0"));
 2562         VNASSERT(pctrie_is_empty(&bo->bo_clean.bv_root), vp,
 2563             ("clean blk trie not empty"));
 2564         VNASSERT(bo->bo_dirty.bv_cnt == 0, vp, ("dirtybufcnt not 0"));
 2565         VNASSERT(pctrie_is_empty(&bo->bo_dirty.bv_root), vp,
 2566             ("dirty blk trie not empty"));
 2567         VNASSERT(TAILQ_EMPTY(&vp->v_cache_dst), vp, ("vp has namecache dst"));
 2568         VNASSERT(LIST_EMPTY(&vp->v_cache_src), vp, ("vp has namecache src"));
 2569         VNASSERT(vp->v_cache_dd == NULL, vp, ("vp has namecache for .."));
 2570         VNASSERT(TAILQ_EMPTY(&vp->v_rl.rl_waiters), vp,
 2571             ("Dangling rangelock waiters"));
 2572         VI_UNLOCK(vp);
 2573 #ifdef MAC
 2574         mac_vnode_destroy(vp);
 2575 #endif
 2576         if (vp->v_pollinfo != NULL) {
 2577                 destroy_vpollinfo(vp->v_pollinfo);
 2578                 vp->v_pollinfo = NULL;
 2579         }
 2580 #ifdef INVARIANTS
 2581         /* XXX Elsewhere we detect an already freed vnode via NULL v_op. */
 2582         vp->v_op = NULL;
 2583 #endif
 2584         bzero(&vp->v_un, sizeof(vp->v_un));
 2585         vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 2586         vp->v_iflag = 0;
 2587         vp->v_vflag = 0;
 2588         bo->bo_flag = 0;
 2589         uma_zfree(vnode_zone, vp);
 2590 }
 2591 
 2592 /*
 2593  * Call VOP_INACTIVE on the vnode and manage the DOINGINACT and OWEINACT
 2594  * flags.  DOINGINACT prevents us from recursing in calls to vinactive.
 2595  * OWEINACT tracks whether a vnode missed a call to inactive due to a
 2596  * failed lock upgrade.
 2597  */
 2598 void
 2599 vinactive(struct vnode *vp, struct thread *td)
 2600 {
 2601         struct vm_object *obj;
 2602 
 2603         ASSERT_VOP_ELOCKED(vp, "vinactive");
 2604         ASSERT_VI_LOCKED(vp, "vinactive");
 2605         VNASSERT((vp->v_iflag & VI_DOINGINACT) == 0, vp,
 2606             ("vinactive: recursed on VI_DOINGINACT"));
 2607         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 2608         vp->v_iflag |= VI_DOINGINACT;
 2609         vp->v_iflag &= ~VI_OWEINACT;
 2610         VI_UNLOCK(vp);
 2611         /*
 2612          * Before moving off the active list, we must be sure that any
 2613          * modified pages are converted into the vnode's dirty
 2614          * buffers, since these will no longer be checked once the
 2615          * vnode is on the inactive list.
 2616          *
 2617          * The write-out of the dirty pages is asynchronous.  At the
 2618          * point that VOP_INACTIVE() is called, there could still be
 2619          * pending I/O and dirty pages in the object.
 2620          */
 2621         obj = vp->v_object;
 2622         if (obj != NULL && (obj->flags & OBJ_MIGHTBEDIRTY) != 0) {
 2623                 VM_OBJECT_WLOCK(obj);
 2624                 vm_object_page_clean(obj, 0, 0, OBJPC_NOSYNC);
 2625                 VM_OBJECT_WUNLOCK(obj);
 2626         }
 2627         VOP_INACTIVE(vp, td);
 2628         VI_LOCK(vp);
 2629         VNASSERT(vp->v_iflag & VI_DOINGINACT, vp,
 2630             ("vinactive: lost VI_DOINGINACT"));
 2631         vp->v_iflag &= ~VI_DOINGINACT;
 2632 }
 2633 
 2634 /*
 2635  * Remove any vnodes in the vnode table belonging to mount point mp.
 2636  *
 2637  * If FORCECLOSE is not specified, there should not be any active ones,
 2638  * return error if any are found (nb: this is a user error, not a
 2639  * system error). If FORCECLOSE is specified, detach any active vnodes
 2640  * that are found.
 2641  *
 2642  * If WRITECLOSE is set, only flush out regular file vnodes open for
 2643  * writing.
 2644  *
 2645  * SKIPSYSTEM causes any vnodes marked VV_SYSTEM to be skipped.
 2646  *
 2647  * `rootrefs' specifies the base reference count for the root vnode
 2648  * of this filesystem. The root vnode is considered busy if its
 2649  * v_usecount exceeds this value. On a successful return, vflush(, td)
 2650  * will call vrele() on the root vnode exactly rootrefs times.
 2651  * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must
 2652  * be zero.
 2653  */
 2654 #ifdef DIAGNOSTIC
 2655 static int busyprt = 0;         /* print out busy vnodes */
 2656 SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, "Print out busy vnodes");
 2657 #endif
 2658 
 2659 int
 2660 vflush(struct mount *mp, int rootrefs, int flags, struct thread *td)
 2661 {
 2662         struct vnode *vp, *mvp, *rootvp = NULL;
 2663         struct vattr vattr;
 2664         int busy = 0, error;
 2665 
 2666         CTR4(KTR_VFS, "%s: mp %p with rootrefs %d and flags %d", __func__, mp,
 2667             rootrefs, flags);
 2668         if (rootrefs > 0) {
 2669                 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0,
 2670                     ("vflush: bad args"));
 2671                 /*
 2672                  * Get the filesystem root vnode. We can vput() it
 2673                  * immediately, since with rootrefs > 0, it won't go away.
 2674                  */
 2675                 if ((error = VFS_ROOT(mp, LK_EXCLUSIVE, &rootvp)) != 0) {
 2676                         CTR2(KTR_VFS, "%s: vfs_root lookup failed with %d",
 2677                             __func__, error);
 2678                         return (error);
 2679                 }
 2680                 vput(rootvp);
 2681         }
 2682 loop:
 2683         MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
 2684                 vholdl(vp);
 2685                 error = vn_lock(vp, LK_INTERLOCK | LK_EXCLUSIVE);
 2686                 if (error) {
 2687                         vdrop(vp);
 2688                         MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
 2689                         goto loop;
 2690                 }
 2691                 /*
 2692                  * Skip over a vnodes marked VV_SYSTEM.
 2693                  */
 2694                 if ((flags & SKIPSYSTEM) && (vp->v_vflag & VV_SYSTEM)) {
 2695                         VOP_UNLOCK(vp, 0);
 2696                         vdrop(vp);
 2697                         continue;
 2698                 }
 2699                 /*
 2700                  * If WRITECLOSE is set, flush out unlinked but still open
 2701                  * files (even if open only for reading) and regular file
 2702                  * vnodes open for writing.
 2703                  */
 2704                 if (flags & WRITECLOSE) {
 2705                         if (vp->v_object != NULL) {
 2706                                 VM_OBJECT_WLOCK(vp->v_object);
 2707                                 vm_object_page_clean(vp->v_object, 0, 0, 0);
 2708                                 VM_OBJECT_WUNLOCK(vp->v_object);
 2709                         }
 2710                         error = VOP_FSYNC(vp, MNT_WAIT, td);
 2711                         if (error != 0) {
 2712                                 VOP_UNLOCK(vp, 0);
 2713                                 vdrop(vp);
 2714                                 MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
 2715                                 return (error);
 2716                         }
 2717                         error = VOP_GETATTR(vp, &vattr, td->td_ucred);
 2718                         VI_LOCK(vp);
 2719 
 2720                         if ((vp->v_type == VNON ||
 2721                             (error == 0 && vattr.va_nlink > 0)) &&
 2722                             (vp->v_writecount == 0 || vp->v_type != VREG)) {
 2723                                 VOP_UNLOCK(vp, 0);
 2724                                 vdropl(vp);
 2725                                 continue;
 2726                         }
 2727                 } else
 2728                         VI_LOCK(vp);
 2729                 /*
 2730                  * With v_usecount == 0, all we need to do is clear out the
 2731                  * vnode data structures and we are done.
 2732                  *
 2733                  * If FORCECLOSE is set, forcibly close the vnode.
 2734                  */
 2735                 if (vp->v_usecount == 0 || (flags & FORCECLOSE)) {
 2736                         vgonel(vp);
 2737                 } else {
 2738                         busy++;
 2739 #ifdef DIAGNOSTIC
 2740                         if (busyprt)
 2741                                 vprint("vflush: busy vnode", vp);
 2742 #endif
 2743                 }
 2744                 VOP_UNLOCK(vp, 0);
 2745                 vdropl(vp);
 2746         }
 2747         if (rootrefs > 0 && (flags & FORCECLOSE) == 0) {
 2748                 /*
 2749                  * If just the root vnode is busy, and if its refcount
 2750                  * is equal to `rootrefs', then go ahead and kill it.
 2751                  */
 2752                 VI_LOCK(rootvp);
 2753                 KASSERT(busy > 0, ("vflush: not busy"));
 2754                 VNASSERT(rootvp->v_usecount >= rootrefs, rootvp,
 2755                     ("vflush: usecount %d < rootrefs %d",
 2756                      rootvp->v_usecount, rootrefs));
 2757                 if (busy == 1 && rootvp->v_usecount == rootrefs) {
 2758                         VOP_LOCK(rootvp, LK_EXCLUSIVE|LK_INTERLOCK);
 2759                         vgone(rootvp);
 2760                         VOP_UNLOCK(rootvp, 0);
 2761                         busy = 0;
 2762                 } else
 2763                         VI_UNLOCK(rootvp);
 2764         }
 2765         if (busy) {
 2766                 CTR2(KTR_VFS, "%s: failing as %d vnodes are busy", __func__,
 2767                     busy);
 2768                 return (EBUSY);
 2769         }
 2770         for (; rootrefs > 0; rootrefs--)
 2771                 vrele(rootvp);
 2772         return (0);
 2773 }
 2774 
 2775 /*
 2776  * Recycle an unused vnode to the front of the free list.
 2777  */
 2778 int
 2779 vrecycle(struct vnode *vp)
 2780 {
 2781         int recycled;
 2782 
 2783         ASSERT_VOP_ELOCKED(vp, "vrecycle");
 2784         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 2785         recycled = 0;
 2786         VI_LOCK(vp);
 2787         if (vp->v_usecount == 0) {
 2788                 recycled = 1;
 2789                 vgonel(vp);
 2790         }
 2791         VI_UNLOCK(vp);
 2792         return (recycled);
 2793 }
 2794 
 2795 /*
 2796  * Eliminate all activity associated with a vnode
 2797  * in preparation for reuse.
 2798  */
 2799 void
 2800 vgone(struct vnode *vp)
 2801 {
 2802         VI_LOCK(vp);
 2803         vgonel(vp);
 2804         VI_UNLOCK(vp);
 2805 }
 2806 
 2807 static void
 2808 notify_lowervp_vfs_dummy(struct mount *mp __unused,
 2809     struct vnode *lowervp __unused)
 2810 {
 2811 }
 2812 
 2813 /*
 2814  * Notify upper mounts about reclaimed or unlinked vnode.
 2815  */
 2816 void
 2817 vfs_notify_upper(struct vnode *vp, int event)
 2818 {
 2819         static struct vfsops vgonel_vfsops = {
 2820                 .vfs_reclaim_lowervp = notify_lowervp_vfs_dummy,
 2821                 .vfs_unlink_lowervp = notify_lowervp_vfs_dummy,
 2822         };
 2823         struct mount *mp, *ump, *mmp;
 2824 
 2825         mp = vp->v_mount;
 2826         if (mp == NULL)
 2827                 return;
 2828 
 2829         MNT_ILOCK(mp);
 2830         if (TAILQ_EMPTY(&mp->mnt_uppers))
 2831                 goto unlock;
 2832         MNT_IUNLOCK(mp);
 2833         mmp = malloc(sizeof(struct mount), M_TEMP, M_WAITOK | M_ZERO);
 2834         mmp->mnt_op = &vgonel_vfsops;
 2835         mmp->mnt_kern_flag |= MNTK_MARKER;
 2836         MNT_ILOCK(mp);
 2837         mp->mnt_kern_flag |= MNTK_VGONE_UPPER;
 2838         for (ump = TAILQ_FIRST(&mp->mnt_uppers); ump != NULL;) {
 2839                 if ((ump->mnt_kern_flag & MNTK_MARKER) != 0) {
 2840                         ump = TAILQ_NEXT(ump, mnt_upper_link);
 2841                         continue;
 2842                 }
 2843                 TAILQ_INSERT_AFTER(&mp->mnt_uppers, ump, mmp, mnt_upper_link);
 2844                 MNT_IUNLOCK(mp);
 2845                 switch (event) {
 2846                 case VFS_NOTIFY_UPPER_RECLAIM:
 2847                         VFS_RECLAIM_LOWERVP(ump, vp);
 2848                         break;
 2849                 case VFS_NOTIFY_UPPER_UNLINK:
 2850                         VFS_UNLINK_LOWERVP(ump, vp);
 2851                         break;
 2852                 default:
 2853                         KASSERT(0, ("invalid event %d", event));
 2854                         break;
 2855                 }
 2856                 MNT_ILOCK(mp);
 2857                 ump = TAILQ_NEXT(mmp, mnt_upper_link);
 2858                 TAILQ_REMOVE(&mp->mnt_uppers, mmp, mnt_upper_link);
 2859         }
 2860         free(mmp, M_TEMP);
 2861         mp->mnt_kern_flag &= ~MNTK_VGONE_UPPER;
 2862         if ((mp->mnt_kern_flag & MNTK_VGONE_WAITER) != 0) {
 2863                 mp->mnt_kern_flag &= ~MNTK_VGONE_WAITER;
 2864                 wakeup(&mp->mnt_uppers);
 2865         }
 2866 unlock:
 2867         MNT_IUNLOCK(mp);
 2868 }
 2869 
 2870 /*
 2871  * vgone, with the vp interlock held.
 2872  */
 2873 static void
 2874 vgonel(struct vnode *vp)
 2875 {
 2876         struct thread *td;
 2877         int oweinact;
 2878         int active;
 2879         struct mount *mp;
 2880 
 2881         ASSERT_VOP_ELOCKED(vp, "vgonel");
 2882         ASSERT_VI_LOCKED(vp, "vgonel");
 2883         VNASSERT(vp->v_holdcnt, vp,
 2884             ("vgonel: vp %p has no reference.", vp));
 2885         CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
 2886         td = curthread;
 2887 
 2888         /*
 2889          * Don't vgonel if we're already doomed.
 2890          */
 2891         if (vp->v_iflag & VI_DOOMED)
 2892                 return;
 2893         vp->v_iflag |= VI_DOOMED;
 2894 
 2895         /*
 2896          * Check to see if the vnode is in use.  If so, we have to call
 2897          * VOP_CLOSE() and VOP_INACTIVE().
 2898          */
 2899         active = vp->v_usecount;
 2900         oweinact = (vp->v_iflag & VI_OWEINACT);
 2901         VI_UNLOCK(vp);
 2902         vfs_notify_upper(vp, VFS_NOTIFY_UPPER_RECLAIM);
 2903 
 2904         /*
 2905          * If purging an active vnode, it must be closed and
 2906          * deactivated before being reclaimed.
 2907          */
 2908         if (active)
 2909                 VOP_CLOSE(vp, FNONBLOCK, NOCRED, td);
 2910         if (oweinact || active) {
 2911                 VI_LOCK(vp);
 2912                 if ((vp->v_iflag & VI_DOINGINACT) == 0)
 2913                         vinactive(vp, td);
 2914                 VI_UNLOCK(vp);
 2915         }
 2916         if (vp->v_type == VSOCK)
 2917                 vfs_unp_reclaim(vp);
 2918 
 2919         /*
 2920          * Clean out any buffers associated with the vnode.
 2921          * If the flush fails, just toss the buffers.
 2922          */
 2923         mp = NULL;
 2924         if (!TAILQ_EMPTY(&vp->v_bufobj.bo_dirty.bv_hd))
 2925                 (void) vn_start_secondary_write(vp, &mp, V_WAIT);
 2926         if (vinvalbuf(vp, V_SAVE, 0, 0) != 0) {
 2927                 while (vinvalbuf(vp, 0, 0, 0) != 0)
 2928                         ;
 2929         }
 2930 
 2931         BO_LOCK(&vp->v_bufobj);
 2932         KASSERT(TAILQ_EMPTY(&vp->v_bufobj.bo_dirty.bv_hd) &&
 2933             vp->v_bufobj.bo_dirty.bv_cnt == 0 &&
 2934             TAILQ_EMPTY(&vp->v_bufobj.bo_clean.bv_hd) &&
 2935             vp->v_bufobj.bo_clean.bv_cnt == 0,
 2936             ("vp %p bufobj not invalidated", vp));
 2937 
 2938         /*
 2939          * For VMIO bufobj, BO_DEAD is set in vm_object_terminate()
 2940          * after the object's page queue is flushed.
 2941          */
 2942         if (vp->v_bufobj.bo_object == NULL)
 2943                 vp->v_bufobj.bo_flag |= BO_DEAD;
 2944         BO_UNLOCK(&vp->v_bufobj);
 2945 
 2946         /*
 2947          * Reclaim the vnode.
 2948          */
 2949         if (VOP_RECLAIM(vp, td))
 2950                 panic("vgone: cannot reclaim");
 2951         if (mp != NULL)
 2952                 vn_finished_secondary_write(mp);
 2953         VNASSERT(vp->v_object == NULL, vp,
 2954             ("vop_reclaim left v_object vp=%p, tag=%s", vp, vp->v_tag));
 2955         /*
 2956          * Clear the advisory locks and wake up waiting threads.
 2957          */
 2958         (void)VOP_ADVLOCKPURGE(vp);
 2959         vp->v_lockf = NULL;
 2960         /*
 2961          * Delete from old mount point vnode list.
 2962          */
 2963         delmntque(vp);
 2964         cache_purge(vp);
 2965         /*
 2966          * Done with purge, reset to the standard lock and invalidate
 2967          * the vnode.
 2968          */
 2969         VI_LOCK(vp);
 2970         vp->v_vnlock = &vp->v_lock;
 2971         vp->v_op = &dead_vnodeops;
 2972         vp->v_tag = "none";
 2973         vp->v_type = VBAD;
 2974 }
 2975 
 2976 /*
 2977  * Calculate the total number of references to a special device.
 2978  */
 2979 int
 2980 vcount(struct vnode *vp)
 2981 {
 2982         int count;
 2983 
 2984         dev_lock();
 2985         count = vp->v_rdev->si_usecount;
 2986         dev_unlock();
 2987         return (count);
 2988 }
 2989 
 2990 /*
 2991  * Same as above, but using the struct cdev *as argument
 2992  */
 2993 int
 2994 count_dev(struct cdev *dev)
 2995 {
 2996         int count;
 2997 
 2998         dev_lock();
 2999         count = dev->si_usecount;
 3000         dev_unlock();
 3001         return(count);
 3002 }
 3003 
 3004 /*
 3005  * Print out a description of a vnode.
 3006  */
 3007 static char *typename[] =
 3008 {"VNON", "VREG", "VDIR", "VBLK", "VCHR", "VLNK", "VSOCK", "VFIFO", "VBAD",
 3009  "VMARKER"};
 3010 
 3011 void
 3012 vn_printf(struct vnode *vp, const char *fmt, ...)
 3013 {
 3014         va_list ap;
 3015         char buf[256], buf2[16];
 3016         u_long flags;
 3017 
 3018         va_start(ap, fmt);
 3019         vprintf(fmt, ap);
 3020         va_end(ap);
 3021         printf("%p: ", (void *)vp);
 3022         printf("tag %s, type %s\n", vp->v_tag, typename[vp->v_type]);
 3023         printf("    usecount %d, writecount %d, refcount %d mountedhere %p\n",
 3024             vp->v_usecount, vp->v_writecount, vp->v_holdcnt, vp->v_mountedhere);
 3025         buf[0] = '\0';
 3026         buf[1] = '\0';
 3027         if (vp->v_vflag & VV_ROOT)
 3028                 strlcat(buf, "|VV_ROOT", sizeof(buf));
 3029         if (vp->v_vflag & VV_ISTTY)
 3030                 strlcat(buf, "|VV_ISTTY", sizeof(buf));
 3031         if (vp->v_vflag & VV_NOSYNC)
 3032                 strlcat(buf, "|VV_NOSYNC", sizeof(buf));
 3033         if (vp->v_vflag & VV_ETERNALDEV)
 3034                 strlcat(buf, "|VV_ETERNALDEV", sizeof(buf));
 3035         if (vp->v_vflag & VV_CACHEDLABEL)
 3036                 strlcat(buf, "|VV_CACHEDLABEL", sizeof(buf));
 3037         if (vp->v_vflag & VV_TEXT)
 3038                 strlcat(buf, "|VV_TEXT", sizeof(buf));
 3039         if (vp->v_vflag & VV_COPYONWRITE)
 3040                 strlcat(buf, "|VV_COPYONWRITE", sizeof(buf));
 3041         if (vp->v_vflag & VV_SYSTEM)
 3042                 strlcat(buf, "|VV_SYSTEM", sizeof(buf));
 3043         if (vp->v_vflag & VV_PROCDEP)
 3044                 strlcat(buf, "|VV_PROCDEP", sizeof(buf));
 3045         if (vp->v_vflag & VV_NOKNOTE)
 3046                 strlcat(buf, "|VV_NOKNOTE", sizeof(buf));
 3047         if (vp->v_vflag & VV_DELETED)
 3048                 strlcat(buf, "|VV_DELETED", sizeof(buf));
 3049         if (vp->v_vflag & VV_MD)
 3050                 strlcat(buf, "|VV_MD", sizeof(buf));
 3051         if (vp->v_vflag & VV_FORCEINSMQ)
 3052                 strlcat(buf, "|VV_FORCEINSMQ", sizeof(buf));
 3053         flags = vp->v_vflag & ~(VV_ROOT | VV_ISTTY | VV_NOSYNC | VV_ETERNALDEV |
 3054             VV_CACHEDLABEL | VV_TEXT | VV_COPYONWRITE | VV_SYSTEM | VV_PROCDEP |
 3055             VV_NOKNOTE | VV_DELETED | VV_MD | VV_FORCEINSMQ);
 3056         if (flags != 0) {
 3057                 snprintf(buf2, sizeof(buf2), "|VV(0x%lx)", flags);
 3058                 strlcat(buf, buf2, sizeof(buf));
 3059         }
 3060         if (vp->v_iflag & VI_MOUNT)
 3061                 strlcat(buf, "|VI_MOUNT", sizeof(buf));
 3062         if (vp->v_iflag & VI_DOOMED)
 3063                 strlcat(buf, "|VI_DOOMED", sizeof(buf));
 3064         if (vp->v_iflag & VI_FREE)
 3065                 strlcat(buf, "|VI_FREE", sizeof(buf));
 3066         if (vp->v_iflag & VI_ACTIVE)
 3067                 strlcat(buf, "|VI_ACTIVE", sizeof(buf));
 3068         if (vp->v_iflag & VI_DOINGINACT)
 3069                 strlcat(buf, "|VI_DOINGINACT", sizeof(buf));
 3070         if (vp->v_iflag & VI_OWEINACT)
 3071                 strlcat(buf, "|VI_OWEINACT", sizeof(buf));
 3072         flags = vp->v_iflag & ~(VI_MOUNT | VI_DOOMED | VI_FREE |
 3073             VI_ACTIVE | VI_DOINGINACT | VI_OWEINACT);
 3074         if (flags != 0) {
 3075                 snprintf(buf2, sizeof(buf2), "|VI(0x%lx)", flags);
 3076                 strlcat(buf, buf2, sizeof(buf));
 3077         }
 3078         printf("    flags (%s)\n", buf + 1);
 3079         if (mtx_owned(VI_MTX(vp)))
 3080                 printf(" VI_LOCKed");
 3081         if (vp->v_object != NULL)
 3082                 printf("    v_object %p ref %d pages %d "
 3083                     "cleanbuf %d dirtybuf %d\n",
 3084                     vp->v_object, vp->v_object->ref_count,
 3085                     vp->v_object->resident_page_count,
 3086                     vp->v_bufobj.bo_clean.bv_cnt,
 3087                     vp->v_bufobj.bo_dirty.bv_cnt);
 3088         printf("    ");
 3089         lockmgr_printinfo(vp->v_vnlock);
 3090         if (vp->v_data != NULL)
 3091                 VOP_PRINT(vp);
 3092 }
 3093 
 3094 #ifdef DDB
 3095 /*
 3096  * List all of the locked vnodes in the system.
 3097  * Called when debugging the kernel.
 3098  */
 3099 DB_SHOW_COMMAND(lockedvnods, lockedvnodes)
 3100 {
 3101         struct mount *mp;
 3102         struct vnode *vp;
 3103 
 3104         /*
 3105          * Note: because this is DDB, we can't obey the locking semantics
 3106          * for these structures, which means we could catch an inconsistent
 3107          * state and dereference a nasty pointer.  Not much to be done
 3108          * about that.
 3109          */
 3110         db_printf("Locked vnodes\n");
 3111         TAILQ_FOREACH(mp, &mountlist, mnt_list) {
 3112                 TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
 3113                         if (vp->v_type != VMARKER && VOP_ISLOCKED(vp))
 3114                                 vprint("", vp);
 3115                 }
 3116         }
 3117 }
 3118 
 3119 /*
 3120  * Show details about the given vnode.
 3121  */
 3122 DB_SHOW_COMMAND(vnode, db_show_vnode)
 3123 {
 3124         struct vnode *vp;
 3125 
 3126         if (!have_addr)
 3127                 return;
 3128         vp = (struct vnode *)addr;
 3129         vn_printf(vp, "vnode ");
 3130 }
 3131 
 3132 /*
 3133  * Show details about the given mount point.
 3134  */
 3135 DB_SHOW_COMMAND(mount, db_show_mount)
 3136 {
 3137         struct mount *mp;
 3138         struct vfsopt *opt;
 3139         struct statfs *sp;
 3140         struct vnode *vp;
 3141         char buf[512];
 3142         uint64_t mflags;
 3143         u_int flags;
 3144 
 3145         if (!have_addr) {
 3146                 /* No address given, print short info about all mount points. */
 3147                 TAILQ_FOREACH(mp, &mountlist, mnt_list) {
 3148                         db_printf("%p %s on %s (%s)\n", mp,
 3149                             mp->mnt_stat.f_mntfromname,
 3150                             mp->mnt_stat.f_mntonname,
 3151                             mp->mnt_stat.f_fstypename);
 3152                         if (db_pager_quit)
 3153                                 break;
 3154                 }
 3155                 db_printf("\nMore info: show mount <addr>\n");
 3156                 return;
 3157         }
 3158 
 3159         mp = (struct mount *)addr;
 3160         db_printf("%p %s on %s (%s)\n", mp, mp->mnt_stat.f_mntfromname,
 3161             mp->mnt_stat.f_mntonname, mp->mnt_stat.f_fstypename);
 3162 
 3163         buf[0] = '\0';
 3164         mflags = mp->mnt_flag;
 3165 #define MNT_FLAG(flag)  do {                                            \
 3166         if (mflags & (flag)) {                                          \
 3167                 if (buf[0] != '\0')                                     \
 3168                         strlcat(buf, ", ", sizeof(buf));                \
 3169                 strlcat(buf, (#flag) + 4, sizeof(buf));                 \
 3170                 mflags &= ~(flag);                                      \
 3171         }                                                               \
 3172 } while (0)
 3173         MNT_FLAG(MNT_RDONLY);
 3174         MNT_FLAG(MNT_SYNCHRONOUS);
 3175         MNT_FLAG(MNT_NOEXEC);
 3176         MNT_FLAG(MNT_NOSUID);
 3177         MNT_FLAG(MNT_NFS4ACLS);
 3178         MNT_FLAG(MNT_UNION);
 3179         MNT_FLAG(MNT_ASYNC);
 3180         MNT_FLAG(MNT_SUIDDIR);
 3181         MNT_FLAG(MNT_SOFTDEP);
 3182         MNT_FLAG(MNT_NOSYMFOLLOW);
 3183         MNT_FLAG(MNT_GJOURNAL);
 3184         MNT_FLAG(MNT_MULTILABEL);
 3185         MNT_FLAG(MNT_ACLS);
 3186         MNT_FLAG(MNT_NOATIME);
 3187         MNT_FLAG(MNT_NOCLUSTERR);
 3188         MNT_FLAG(MNT_NOCLUSTERW);
 3189         MNT_FLAG(MNT_SUJ);
 3190         MNT_FLAG(MNT_EXRDONLY);
 3191         MNT_FLAG(MNT_EXPORTED);
 3192         MNT_FLAG(MNT_DEFEXPORTED);
 3193         MNT_FLAG(MNT_EXPORTANON);
 3194         MNT_FLAG(MNT_EXKERB);
 3195         MNT_FLAG(MNT_EXPUBLIC);
 3196         MNT_FLAG(MNT_LOCAL);
 3197         MNT_FLAG(MNT_QUOTA);
 3198         MNT_FLAG(MNT_ROOTFS);
 3199         MNT_FLAG(MNT_USER);
 3200         MNT_FLAG(MNT_IGNORE);
 3201         MNT_FLAG(MNT_UPDATE);
 3202         MNT_FLAG(MNT_DELEXPORT);
 3203         MNT_FLAG(MNT_RELOAD);
 3204         MNT_FLAG(MNT_FORCE);
 3205         MNT_FLAG(MNT_SNAPSHOT);
 3206         MNT_FLAG(MNT_BYFSID);
 3207 #undef MNT_FLAG
 3208         if (mflags != 0) {
 3209                 if (buf[0] != '\0')
 3210                         strlcat(buf, ", ", sizeof(buf));
 3211                 snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf),
 3212                     "0x%016jx", mflags);
 3213         }
 3214         db_printf("    mnt_flag = %s\n", buf);
 3215 
 3216         buf[0] = '\0';
 3217         flags = mp->mnt_kern_flag;
 3218 #define MNT_KERN_FLAG(flag)     do {                                    \
 3219         if (flags & (flag)) {                                           \
 3220                 if (buf[0] != '\0')                                     \
 3221                         strlcat(buf, ", ", sizeof(buf));                \
 3222                 strlcat(buf, (#flag) + 5, sizeof(buf));                 \
 3223                 flags &= ~(flag);                                       \
 3224         }                                                               \
 3225 } while (0)
 3226         MNT_KERN_FLAG(MNTK_UNMOUNTF);
 3227         MNT_KERN_FLAG(MNTK_ASYNC);
 3228         MNT_KERN_FLAG(MNTK_SOFTDEP);
 3229         MNT_KERN_FLAG(MNTK_NOINSMNTQ);
 3230         MNT_KERN_FLAG(MNTK_DRAINING);
 3231         MNT_KERN_FLAG(MNTK_REFEXPIRE);
 3232         MNT_KERN_FLAG(MNTK_EXTENDED_SHARED);
 3233         MNT_KERN_FLAG(MNTK_SHARED_WRITES);
 3234         MNT_KERN_FLAG(MNTK_NO_IOPF);
 3235         MNT_KERN_FLAG(MNTK_VGONE_UPPER);
 3236         MNT_KERN_FLAG(MNTK_VGONE_WAITER);
 3237         MNT_KERN_FLAG(MNTK_LOOKUP_EXCL_DOTDOT);
 3238         MNT_KERN_FLAG(MNTK_MARKER);
 3239         MNT_KERN_FLAG(MNTK_USES_BCACHE);
 3240         MNT_KERN_FLAG(MNTK_NOASYNC);
 3241         MNT_KERN_FLAG(MNTK_UNMOUNT);
 3242         MNT_KERN_FLAG(MNTK_MWAIT);
 3243         MNT_KERN_FLAG(MNTK_SUSPEND);
 3244         MNT_KERN_FLAG(MNTK_SUSPEND2);
 3245         MNT_KERN_FLAG(MNTK_SUSPENDED);
 3246         MNT_KERN_FLAG(MNTK_LOOKUP_SHARED);
 3247         MNT_KERN_FLAG(MNTK_NOKNOTE);
 3248 #undef MNT_KERN_FLAG
 3249         if (flags != 0) {
 3250                 if (buf[0] != '\0')
 3251                         strlcat(buf, ", ", sizeof(buf));
 3252                 snprintf(buf + strlen(buf), sizeof(buf) - strlen(buf),
 3253                     "0x%08x", flags);
 3254         }
 3255         db_printf("    mnt_kern_flag = %s\n", buf);
 3256 
 3257         db_printf("    mnt_opt = ");
 3258         opt = TAILQ_FIRST(mp->mnt_opt);
 3259         if (opt != NULL) {
 3260                 db_printf("%s", opt->name);
 3261                 opt = TAILQ_NEXT(opt, link);
 3262                 while (opt != NULL) {
 3263                         db_printf(", %s", opt->name);
 3264                         opt = TAILQ_NEXT(opt, link);
 3265                 }
 3266         }
 3267         db_printf("\n");
 3268 
 3269         sp = &mp->mnt_stat;
 3270         db_printf("    mnt_stat = { version=%u type=%u flags=0x%016jx "
 3271             "bsize=%ju iosize=%ju blocks=%ju bfree=%ju bavail=%jd files=%ju "
 3272             "ffree=%jd syncwrites=%ju asyncwrites=%ju syncreads=%ju "
 3273             "asyncreads=%ju namemax=%u owner=%u fsid=[%d, %d] }\n",
 3274             (u_int)sp->f_version, (u_int)sp->f_type, (uintmax_t)sp->f_flags,
 3275             (uintmax_t)sp->f_bsize, (uintmax_t)sp->f_iosize,
 3276             (uintmax_t)sp->f_blocks, (uintmax_t)sp->f_bfree,
 3277             (intmax_t)sp->f_bavail, (uintmax_t)sp->f_files,
 3278             (intmax_t)sp->f_ffree, (uintmax_t)sp->f_syncwrites,
 3279             (uintmax_t)sp->f_asyncwrites, (uintmax_t)sp->f_syncreads,
 3280             (uintmax_t)sp->f_asyncreads, (u_int)sp->f_namemax,
 3281             (u_int)sp->f_owner, (int)sp->f_fsid.val[0], (int)sp->f_fsid.val[1]);
 3282 
 3283         db_printf("    mnt_cred = { uid=%u ruid=%u",
 3284             (u_int)mp->mnt_cred->cr_uid, (u_int)mp->mnt_cred->cr_ruid);
 3285         if (jailed(mp->mnt_cred))
 3286                 db_printf(", jail=%d", mp->mnt_cred->cr_prison->pr_id);
 3287         db_printf(" }\n");
 3288         db_printf("    mnt_ref = %d\n", mp->mnt_ref);
 3289         db_printf("    mnt_gen = %d\n", mp->mnt_gen);
 3290         db_printf("    mnt_nvnodelistsize = %d\n", mp->mnt_nvnodelistsize);
 3291         db_printf("    mnt_activevnodelistsize = %d\n",
 3292             mp->mnt_activevnodelistsize);
 3293         db_printf("    mnt_writeopcount = %d\n", mp->mnt_writeopcount);
 3294         db_printf("    mnt_maxsymlinklen = %d\n", mp->mnt_maxsymlinklen);
 3295         db_printf("    mnt_iosize_max = %d\n", mp->mnt_iosize_max);
 3296         db_printf("    mnt_hashseed = %u\n", mp->mnt_hashseed);
 3297         db_printf("    mnt_lockref = %d\n", mp->mnt_lockref);
 3298         db_printf("    mnt_secondary_writes = %d\n", mp->mnt_secondary_writes);
 3299         db_printf("    mnt_secondary_accwrites = %d\n",
 3300             mp->mnt_secondary_accwrites);
 3301         db_printf("    mnt_gjprovider = %s\n",
 3302             mp->mnt_gjprovider != NULL ? mp->mnt_gjprovider : "NULL");
 3303 
 3304         db_printf("\n\nList of active vnodes\n");
 3305         TAILQ_FOREACH(vp, &mp->mnt_activevnodelist, v_actfreelist) {
 3306                 if (vp->v_type != VMARKER) {
 3307                         vn_printf(vp, "vnode ");
 3308                         if (db_pager_quit)
 3309                                 break;
 3310                 }
 3311         }
 3312         db_printf("\n\nList of inactive vnodes\n");
 3313         TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
 3314                 if (vp->v_type != VMARKER && (vp->v_iflag & VI_ACTIVE) == 0) {
 3315                         vn_printf(vp, "vnode ");
 3316                         if (db_pager_quit)
 3317                                 break;
 3318                 }
 3319         }
 3320 }
 3321 #endif  /* DDB */
 3322 
 3323 /*
 3324  * Fill in a struct xvfsconf based on a struct vfsconf.
 3325  */
 3326 static int
 3327 vfsconf2x(struct sysctl_req *req, struct vfsconf *vfsp)
 3328 {
 3329         struct xvfsconf xvfsp;
 3330 
 3331         bzero(&xvfsp, sizeof(xvfsp));
 3332         strcpy(xvfsp.vfc_name, vfsp->vfc_name);
 3333         xvfsp.vfc_typenum = vfsp->vfc_typenum;
 3334         xvfsp.vfc_refcount = vfsp->vfc_refcount;
 3335         xvfsp.vfc_flags = vfsp->vfc_flags;
 3336         /*
 3337          * These are unused in userland, we keep them
 3338          * to not break binary compatibility.
 3339          */
 3340         xvfsp.vfc_vfsops = NULL;
 3341         xvfsp.vfc_next = NULL;
 3342         return (SYSCTL_OUT(req, &xvfsp, sizeof(xvfsp)));
 3343 }
 3344 
 3345 #ifdef COMPAT_FREEBSD32
 3346 struct xvfsconf32 {
 3347         uint32_t        vfc_vfsops;
 3348         char            vfc_name[MFSNAMELEN];
 3349         int32_t         vfc_typenum;
 3350         int32_t         vfc_refcount;
 3351         int32_t         vfc_flags;
 3352         uint32_t        vfc_next;
 3353 };
 3354 
 3355 static int
 3356 vfsconf2x32(struct sysctl_req *req, struct vfsconf *vfsp)
 3357 {
 3358         struct xvfsconf32 xvfsp;
 3359 
 3360         bzero(&xvfsp, sizeof(xvfsp));
 3361         strcpy(xvfsp.vfc_name, vfsp->vfc_name);
 3362         xvfsp.vfc_typenum = vfsp->vfc_typenum;
 3363         xvfsp.vfc_refcount = vfsp->vfc_refcount;
 3364         xvfsp.vfc_flags = vfsp->vfc_flags;
 3365         return (SYSCTL_OUT(req, &xvfsp, sizeof(xvfsp)));
 3366 }
 3367 #endif
 3368 
 3369 /*
 3370  * Top level filesystem related information gathering.
 3371  */
 3372 static int
 3373 sysctl_vfs_conflist(SYSCTL_HANDLER_ARGS)
 3374 {
 3375         struct vfsconf *vfsp;
 3376         int error;
 3377 
 3378         error = 0;
 3379         vfsconf_slock();
 3380         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
 3381 #ifdef COMPAT_FREEBSD32
 3382                 if (req->flags & SCTL_MASK32)
 3383                         error = vfsconf2x32(req, vfsp);
 3384                 else
 3385 #endif
 3386                         error = vfsconf2x(req, vfsp);
 3387                 if (error)
 3388                         break;
 3389         }
 3390         vfsconf_sunlock();
 3391         return (error);
 3392 }
 3393 
 3394 SYSCTL_PROC(_vfs, OID_AUTO, conflist, CTLTYPE_OPAQUE | CTLFLAG_RD |
 3395     CTLFLAG_MPSAFE, NULL, 0, sysctl_vfs_conflist,
 3396     "S,xvfsconf", "List of all configured filesystems");
 3397 
 3398 #ifndef BURN_BRIDGES
 3399 static int      sysctl_ovfs_conf(SYSCTL_HANDLER_ARGS);
 3400 
 3401 static int
 3402 vfs_sysctl(SYSCTL_HANDLER_ARGS)
 3403 {
 3404         int *name = (int *)arg1 - 1;    /* XXX */
 3405         u_int namelen = arg2 + 1;       /* XXX */
 3406         struct vfsconf *vfsp;
 3407 
 3408         log(LOG_WARNING, "userland calling deprecated sysctl, "
 3409             "please rebuild world\n");
 3410 
 3411 #if 1 || defined(COMPAT_PRELITE2)
 3412         /* Resolve ambiguity between VFS_VFSCONF and VFS_GENERIC. */
 3413         if (namelen == 1)
 3414                 return (sysctl_ovfs_conf(oidp, arg1, arg2, req));
 3415 #endif
 3416 
 3417         switch (name[1]) {
 3418         case VFS_MAXTYPENUM:
 3419                 if (namelen != 2)
 3420                         return (ENOTDIR);
 3421                 return (SYSCTL_OUT(req, &maxvfsconf, sizeof(int)));
 3422         case VFS_CONF:
 3423                 if (namelen != 3)
 3424                         return (ENOTDIR);       /* overloaded */
 3425                 vfsconf_slock();
 3426                 TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
 3427                         if (vfsp->vfc_typenum == name[2])
 3428                                 break;
 3429                 }
 3430                 vfsconf_sunlock();
 3431                 if (vfsp == NULL)
 3432                         return (EOPNOTSUPP);
 3433 #ifdef COMPAT_FREEBSD32
 3434                 if (req->flags & SCTL_MASK32)
 3435                         return (vfsconf2x32(req, vfsp));
 3436                 else
 3437 #endif
 3438                         return (vfsconf2x(req, vfsp));
 3439         }
 3440         return (EOPNOTSUPP);
 3441 }
 3442 
 3443 static SYSCTL_NODE(_vfs, VFS_GENERIC, generic, CTLFLAG_RD | CTLFLAG_SKIP |
 3444     CTLFLAG_MPSAFE, vfs_sysctl,
 3445     "Generic filesystem");
 3446 
 3447 #if 1 || defined(COMPAT_PRELITE2)
 3448 
 3449 static int
 3450 sysctl_ovfs_conf(SYSCTL_HANDLER_ARGS)
 3451 {
 3452         int error;
 3453         struct vfsconf *vfsp;
 3454         struct ovfsconf ovfs;
 3455 
 3456         vfsconf_slock();
 3457         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
 3458                 bzero(&ovfs, sizeof(ovfs));
 3459                 ovfs.vfc_vfsops = vfsp->vfc_vfsops;     /* XXX used as flag */
 3460                 strcpy(ovfs.vfc_name, vfsp->vfc_name);
 3461                 ovfs.vfc_index = vfsp->vfc_typenum;
 3462                 ovfs.vfc_refcount = vfsp->vfc_refcount;
 3463                 ovfs.vfc_flags = vfsp->vfc_flags;
 3464                 error = SYSCTL_OUT(req, &ovfs, sizeof ovfs);
 3465                 if (error != 0) {
 3466                         vfsconf_sunlock();
 3467                         return (error);
 3468                 }
 3469         }
 3470         vfsconf_sunlock();
 3471         return (0);
 3472 }
 3473 
 3474 #endif /* 1 || COMPAT_PRELITE2 */
 3475 #endif /* !BURN_BRIDGES */
 3476 
 3477 #define KINFO_VNODESLOP         10
 3478 #ifdef notyet
 3479 /*
 3480  * Dump vnode list (via sysctl).
 3481  */
 3482 /* ARGSUSED */
 3483 static int
 3484 sysctl_vnode(SYSCTL_HANDLER_ARGS)
 3485 {
 3486         struct xvnode *xvn;
 3487         struct mount *mp;
 3488         struct vnode *vp;
 3489         int error, len, n;
 3490 
 3491         /*
 3492          * Stale numvnodes access is not fatal here.
 3493          */
 3494         req->lock = 0;
 3495         len = (numvnodes + KINFO_VNODESLOP) * sizeof *xvn;
 3496         if (!req->oldptr)
 3497                 /* Make an estimate */
 3498                 return (SYSCTL_OUT(req, 0, len));
 3499 
 3500         error = sysctl_wire_old_buffer(req, 0);
 3501         if (error != 0)
 3502                 return (error);
 3503         xvn = malloc(len, M_TEMP, M_ZERO | M_WAITOK);
 3504         n = 0;
 3505         mtx_lock(&mountlist_mtx);
 3506         TAILQ_FOREACH(mp, &mountlist, mnt_list) {
 3507                 if (vfs_busy(mp, MBF_NOWAIT | MBF_MNTLSTLOCK))
 3508                         continue;
 3509                 MNT_ILOCK(mp);
 3510                 TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
 3511                         if (n == len)
 3512                                 break;
 3513                         vref(vp);
 3514                         xvn[n].xv_size = sizeof *xvn;
 3515                         xvn[n].xv_vnode = vp;
 3516                         xvn[n].xv_id = 0;       /* XXX compat */
 3517 #define XV_COPY(field) xvn[n].xv_##field = vp->v_##field
 3518                         XV_COPY(usecount);
 3519                         XV_COPY(writecount);
 3520                         XV_COPY(holdcnt);
 3521                         XV_COPY(mount);
 3522                         XV_COPY(numoutput);
 3523                         XV_COPY(type);
 3524 #undef XV_COPY
 3525                         xvn[n].xv_flag = vp->v_vflag;
 3526 
 3527                         switch (vp->v_type) {
 3528                         case VREG:
 3529                         case VDIR:
 3530                         case VLNK:
 3531                                 break;
 3532                         case VBLK:
 3533                         case VCHR:
 3534                                 if (vp->v_rdev == NULL) {
 3535                                         vrele(vp);
 3536                                         continue;
 3537                                 }
 3538                                 xvn[n].xv_dev = dev2udev(vp->v_rdev);
 3539                                 break;
 3540                         case VSOCK:
 3541                                 xvn[n].xv_socket = vp->v_socket;
 3542                                 break;
 3543                         case VFIFO:
 3544                                 xvn[n].xv_fifo = vp->v_fifoinfo;
 3545                                 break;
 3546                         case VNON:
 3547                         case VBAD:
 3548                         default:
 3549                                 /* shouldn't happen? */
 3550                                 vrele(vp);
 3551                                 continue;
 3552                         }
 3553                         vrele(vp);
 3554                         ++n;
 3555                 }
 3556                 MNT_IUNLOCK(mp);
 3557                 mtx_lock(&mountlist_mtx);
 3558                 vfs_unbusy(mp);
 3559                 if (n == len)
 3560                         break;
 3561         }
 3562         mtx_unlock(&mountlist_mtx);
 3563 
 3564         error = SYSCTL_OUT(req, xvn, n * sizeof *xvn);
 3565         free(xvn, M_TEMP);
 3566         return (error);
 3567 }
 3568 
 3569 SYSCTL_PROC(_kern, KERN_VNODE, vnode, CTLTYPE_OPAQUE | CTLFLAG_RD |
 3570     CTLFLAG_MPSAFE, 0, 0, sysctl_vnode, "S,xvnode",
 3571     "");
 3572 #endif
 3573 
 3574 static void
 3575 unmount_or_warn(struct mount *mp)
 3576 {
 3577         int error;
 3578 
 3579         error = dounmount(mp, MNT_FORCE, curthread);
 3580         if (error != 0 && strcmp(mp->mnt_vfc->vfc_name, "devfs") != 0) {
 3581                 printf("unmount of %s failed (", mp->mnt_stat.f_mntonname);
 3582                 if (error == EBUSY)
 3583                         printf("BUSY)\n");
 3584                 else
 3585                         printf("%d)\n", error);
 3586         }
 3587 }
 3588 
 3589 /*
 3590  * Unmount all filesystems. The list is traversed in reverse order
 3591  * of mounting to avoid dependencies.
 3592  */
 3593 void
 3594 vfs_unmountall(void)
 3595 {
 3596         struct mount *mp, *tmp;
 3597 
 3598         CTR1(KTR_VFS, "%s: unmounting all filesystems", __func__);
 3599 
 3600         /*
 3601          * Since this only runs when rebooting, it is not interlocked.
 3602          */
 3603         TAILQ_FOREACH_REVERSE_SAFE(mp, &mountlist, mntlist, mnt_list, tmp) {
 3604                 vfs_ref(mp);
 3605 
 3606                 /*
 3607                  * Forcibly unmounting "/dev" before "/" would prevent clean
 3608                  * unmount of the latter.
 3609                  */
 3610                 if (mp == rootdevmp)
 3611                         continue;
 3612 
 3613                 unmount_or_warn(mp);
 3614         }
 3615 
 3616         if (rootdevmp != NULL)
 3617                 unmount_or_warn(rootdevmp);
 3618 }
 3619 
 3620 /*
 3621  * perform msync on all vnodes under a mount point
 3622  * the mount point must be locked.
 3623  */
 3624 void
 3625 vfs_msync(struct mount *mp, int flags)
 3626 {
 3627         struct vnode *vp, *mvp;
 3628         struct vm_object *obj;
 3629 
 3630         CTR2(KTR_VFS, "%s: mp %p", __func__, mp);
 3631         MNT_VNODE_FOREACH_ACTIVE(vp, mp, mvp) {
 3632                 obj = vp->v_object;
 3633                 if (obj != NULL && (obj->flags & OBJ_MIGHTBEDIRTY) != 0 &&
 3634                     (flags == MNT_WAIT || VOP_ISLOCKED(vp) == 0)) {
 3635                         if (!vget(vp,
 3636                             LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK,
 3637                             curthread)) {
 3638                                 if (vp->v_vflag & VV_NOSYNC) {  /* unlinked */
 3639                                         vput(vp);
 3640                                         continue;
 3641                                 }
 3642 
 3643                                 obj = vp->v_object;
 3644                                 if (obj != NULL) {
 3645                                         VM_OBJECT_WLOCK(obj);
 3646                                         vm_object_page_clean(obj, 0, 0,
 3647                                             flags == MNT_WAIT ?
 3648                                             OBJPC_SYNC : OBJPC_NOSYNC);
 3649                                         VM_OBJECT_WUNLOCK(obj);
 3650                                 }
 3651                                 vput(vp);
 3652                         }
 3653                 } else
 3654                         VI_UNLOCK(vp);
 3655         }
 3656 }
 3657 
 3658 static void
 3659 destroy_vpollinfo_free(struct vpollinfo *vi)
 3660 {
 3661 
 3662         knlist_destroy(&vi->vpi_selinfo.si_note);
 3663         mtx_destroy(&vi->vpi_lock);
 3664         uma_zfree(vnodepoll_zone, vi);
 3665 }
 3666 
 3667 static void
 3668 destroy_vpollinfo(struct vpollinfo *vi)
 3669 {
 3670 
 3671         knlist_clear(&vi->vpi_selinfo.si_note, 1);
 3672         seldrain(&vi->vpi_selinfo);
 3673         destroy_vpollinfo_free(vi);
 3674 }
 3675 
 3676 /*
 3677  * Initialize per-vnode helper structure to hold poll-related state.
 3678  */
 3679 void
 3680 v_addpollinfo(struct vnode *vp)
 3681 {
 3682         struct vpollinfo *vi;
 3683 
 3684         if (vp->v_pollinfo != NULL)
 3685                 return;
 3686         vi = uma_zalloc(vnodepoll_zone, M_WAITOK);
 3687         mtx_init(&vi->vpi_lock, "vnode pollinfo", NULL, MTX_DEF);
 3688         knlist_init(&vi->vpi_selinfo.si_note, vp, vfs_knllock,
 3689             vfs_knlunlock, vfs_knl_assert_locked, vfs_knl_assert_unlocked);
 3690         VI_LOCK(vp);
 3691         if (vp->v_pollinfo != NULL) {
 3692                 VI_UNLOCK(vp);
 3693                 destroy_vpollinfo_free(vi);
 3694                 return;
 3695         }
 3696         vp->v_pollinfo = vi;
 3697         VI_UNLOCK(vp);
 3698 }
 3699 
 3700 /*
 3701  * Record a process's interest in events which might happen to
 3702  * a vnode.  Because poll uses the historic select-style interface
 3703  * internally, this routine serves as both the ``check for any
 3704  * pending events'' and the ``record my interest in future events''
 3705  * functions.  (These are done together, while the lock is held,
 3706  * to avoid race conditions.)
 3707  */
 3708 int
 3709 vn_pollrecord(struct vnode *vp, struct thread *td, int events)
 3710 {
 3711 
 3712         v_addpollinfo(vp);
 3713         mtx_lock(&vp->v_pollinfo->vpi_lock);
 3714         if (vp->v_pollinfo->vpi_revents & events) {
 3715                 /*
 3716                  * This leaves events we are not interested
 3717                  * in available for the other process which
 3718                  * which presumably had requested them
 3719                  * (otherwise they would never have been
 3720                  * recorded).
 3721                  */
 3722                 events &= vp->v_pollinfo->vpi_revents;
 3723                 vp->v_pollinfo->vpi_revents &= ~events;
 3724 
 3725                 mtx_unlock(&vp->v_pollinfo->vpi_lock);
 3726                 return (events);
 3727         }
 3728         vp->v_pollinfo->vpi_events |= events;
 3729         selrecord(td, &vp->v_pollinfo->vpi_selinfo);
 3730         mtx_unlock(&vp->v_pollinfo->vpi_lock);
 3731         return (0);
 3732 }
 3733 
 3734 /*
 3735  * Routine to create and manage a filesystem syncer vnode.
 3736  */
 3737 #define sync_close ((int (*)(struct  vop_close_args *))nullop)
 3738 static int      sync_fsync(struct  vop_fsync_args *);
 3739 static int      sync_inactive(struct  vop_inactive_args *);
 3740 static int      sync_reclaim(struct  vop_reclaim_args *);
 3741 
 3742 static struct vop_vector sync_vnodeops = {
 3743         .vop_bypass =   VOP_EOPNOTSUPP,
 3744         .vop_close =    sync_close,             /* close */
 3745         .vop_fsync =    sync_fsync,             /* fsync */
 3746         .vop_inactive = sync_inactive,  /* inactive */
 3747         .vop_reclaim =  sync_reclaim,   /* reclaim */
 3748         .vop_lock1 =    vop_stdlock,    /* lock */
 3749         .vop_unlock =   vop_stdunlock,  /* unlock */
 3750         .vop_islocked = vop_stdislocked,        /* islocked */
 3751 };
 3752 
 3753 /*
 3754  * Create a new filesystem syncer vnode for the specified mount point.
 3755  */
 3756 void
 3757 vfs_allocate_syncvnode(struct mount *mp)
 3758 {
 3759         struct vnode *vp;
 3760         struct bufobj *bo;
 3761         static long start, incr, next;
 3762         int error;
 3763 
 3764         /* Allocate a new vnode */
 3765         error = getnewvnode("syncer", mp, &sync_vnodeops, &vp);
 3766         if (error != 0)
 3767                 panic("vfs_allocate_syncvnode: getnewvnode() failed");
 3768         vp->v_type = VNON;
 3769         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 3770         vp->v_vflag |= VV_FORCEINSMQ;
 3771         error = insmntque(vp, mp);
 3772         if (error != 0)
 3773                 panic("vfs_allocate_syncvnode: insmntque() failed");
 3774         vp->v_vflag &= ~VV_FORCEINSMQ;
 3775         VOP_UNLOCK(vp, 0);
 3776         /*
 3777          * Place the vnode onto the syncer worklist. We attempt to
 3778          * scatter them about on the list so that they will go off
 3779          * at evenly distributed times even if all the filesystems
 3780          * are mounted at once.
 3781          */
 3782         next += incr;
 3783         if (next == 0 || next > syncer_maxdelay) {
 3784                 start /= 2;
 3785                 incr /= 2;
 3786                 if (start == 0) {
 3787                         start = syncer_maxdelay / 2;
 3788                         incr = syncer_maxdelay;
 3789                 }
 3790                 next = start;
 3791         }
 3792         bo = &vp->v_bufobj;
 3793         BO_LOCK(bo);
 3794         vn_syncer_add_to_worklist(bo, syncdelay > 0 ? next % syncdelay : 0);
 3795         /* XXX - vn_syncer_add_to_worklist() also grabs and drops sync_mtx. */
 3796         mtx_lock(&sync_mtx);
 3797         sync_vnode_count++;
 3798         if (mp->mnt_syncer == NULL) {
 3799                 mp->mnt_syncer = vp;
 3800                 vp = NULL;
 3801         }
 3802         mtx_unlock(&sync_mtx);
 3803         BO_UNLOCK(bo);
 3804         if (vp != NULL) {
 3805                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 3806                 vgone(vp);
 3807                 vput(vp);
 3808         }
 3809 }
 3810 
 3811 void
 3812 vfs_deallocate_syncvnode(struct mount *mp)
 3813 {
 3814         struct vnode *vp;
 3815 
 3816         mtx_lock(&sync_mtx);
 3817         vp = mp->mnt_syncer;
 3818         if (vp != NULL)
 3819                 mp->mnt_syncer = NULL;
 3820         mtx_unlock(&sync_mtx);
 3821         if (vp != NULL)
 3822                 vrele(vp);
 3823 }
 3824 
 3825 /*
 3826  * Do a lazy sync of the filesystem.
 3827  */
 3828 static int
 3829 sync_fsync(struct vop_fsync_args *ap)
 3830 {
 3831         struct vnode *syncvp = ap->a_vp;
 3832         struct mount *mp = syncvp->v_mount;
 3833         int error, save;
 3834         struct bufobj *bo;
 3835 
 3836         /*
 3837          * We only need to do something if this is a lazy evaluation.
 3838          */
 3839         if (ap->a_waitfor != MNT_LAZY)
 3840                 return (0);
 3841 
 3842         /*
 3843          * Move ourselves to the back of the sync list.
 3844          */
 3845         bo = &syncvp->v_bufobj;
 3846         BO_LOCK(bo);
 3847         vn_syncer_add_to_worklist(bo, syncdelay);
 3848         BO_UNLOCK(bo);
 3849 
 3850         /*
 3851          * Walk the list of vnodes pushing all that are dirty and
 3852          * not already on the sync list.
 3853          */
 3854         if (vfs_busy(mp, MBF_NOWAIT) != 0)
 3855                 return (0);
 3856         if (vn_start_write(NULL, &mp, V_NOWAIT) != 0) {
 3857                 vfs_unbusy(mp);
 3858                 return (0);
 3859         }
 3860         save = curthread_pflags_set(TDP_SYNCIO);
 3861         vfs_msync(mp, MNT_NOWAIT);
 3862         error = VFS_SYNC(mp, MNT_LAZY);
 3863         curthread_pflags_restore(save);
 3864         vn_finished_write(mp);
 3865         vfs_unbusy(mp);
 3866         return (error);
 3867 }
 3868 
 3869 /*
 3870  * The syncer vnode is no referenced.
 3871  */
 3872 static int
 3873 sync_inactive(struct vop_inactive_args *ap)
 3874 {
 3875 
 3876         vgone(ap->a_vp);
 3877         return (0);
 3878 }
 3879 
 3880 /*
 3881  * The syncer vnode is no longer needed and is being decommissioned.
 3882  *
 3883  * Modifications to the worklist must be protected by sync_mtx.
 3884  */
 3885 static int
 3886 sync_reclaim(struct vop_reclaim_args *ap)
 3887 {
 3888         struct vnode *vp = ap->a_vp;
 3889         struct bufobj *bo;
 3890 
 3891         bo = &vp->v_bufobj;
 3892         BO_LOCK(bo);
 3893         mtx_lock(&sync_mtx);
 3894         if (vp->v_mount->mnt_syncer == vp)
 3895                 vp->v_mount->mnt_syncer = NULL;
 3896         if (bo->bo_flag & BO_ONWORKLST) {
 3897                 LIST_REMOVE(bo, bo_synclist);
 3898                 syncer_worklist_len--;
 3899                 sync_vnode_count--;
 3900                 bo->bo_flag &= ~BO_ONWORKLST;
 3901         }
 3902         mtx_unlock(&sync_mtx);
 3903         BO_UNLOCK(bo);
 3904 
 3905         return (0);
 3906 }
 3907 
 3908 /*
 3909  * Check if vnode represents a disk device
 3910  */
 3911 int
 3912 vn_isdisk(struct vnode *vp, int *errp)
 3913 {
 3914         int error;
 3915 
 3916         if (vp->v_type != VCHR) {
 3917                 error = ENOTBLK;
 3918                 goto out;
 3919         }
 3920         error = 0;
 3921         dev_lock();
 3922         if (vp->v_rdev == NULL)
 3923                 error = ENXIO;
 3924         else if (vp->v_rdev->si_devsw == NULL)
 3925                 error = ENXIO;
 3926         else if (!(vp->v_rdev->si_devsw->d_flags & D_DISK))
 3927                 error = ENOTBLK;
 3928         dev_unlock();
 3929 out:
 3930         if (errp != NULL)
 3931                 *errp = error;
 3932         return (error == 0);
 3933 }
 3934 
 3935 /*
 3936  * Common filesystem object access control check routine.  Accepts a
 3937  * vnode's type, "mode", uid and gid, requested access mode, credentials,
 3938  * and optional call-by-reference privused argument allowing vaccess()
 3939  * to indicate to the caller whether privilege was used to satisfy the
 3940  * request (obsoleted).  Returns 0 on success, or an errno on failure.
 3941  */
 3942 int
 3943 vaccess(enum vtype type, mode_t file_mode, uid_t file_uid, gid_t file_gid,
 3944     accmode_t accmode, struct ucred *cred, int *privused)
 3945 {
 3946         accmode_t dac_granted;
 3947         accmode_t priv_granted;
 3948 
 3949         KASSERT((accmode & ~(VEXEC | VWRITE | VREAD | VADMIN | VAPPEND)) == 0,
 3950             ("invalid bit in accmode"));
 3951         KASSERT((accmode & VAPPEND) == 0 || (accmode & VWRITE),
 3952             ("VAPPEND without VWRITE"));
 3953 
 3954         /*
 3955          * Look for a normal, non-privileged way to access the file/directory
 3956          * as requested.  If it exists, go with that.
 3957          */
 3958 
 3959         if (privused != NULL)
 3960                 *privused = 0;
 3961 
 3962         dac_granted = 0;
 3963 
 3964         /* Check the owner. */
 3965         if (cred->cr_uid == file_uid) {
 3966                 dac_granted |= VADMIN;
 3967                 if (file_mode & S_IXUSR)
 3968                         dac_granted |= VEXEC;
 3969                 if (file_mode & S_IRUSR)
 3970                         dac_granted |= VREAD;
 3971                 if (file_mode & S_IWUSR)
 3972                         dac_granted |= (VWRITE | VAPPEND);
 3973 
 3974                 if ((accmode & dac_granted) == accmode)
 3975                         return (0);
 3976 
 3977                 goto privcheck;
 3978         }
 3979 
 3980         /* Otherwise, check the groups (first match) */
 3981         if (groupmember(file_gid, cred)) {
 3982                 if (file_mode & S_IXGRP)
 3983                         dac_granted |= VEXEC;
 3984                 if (file_mode & S_IRGRP)
 3985                         dac_granted |= VREAD;
 3986                 if (file_mode & S_IWGRP)
 3987                         dac_granted |= (VWRITE | VAPPEND);
 3988 
 3989                 if ((accmode & dac_granted) == accmode)
 3990                         return (0);
 3991 
 3992                 goto privcheck;
 3993         }
 3994 
 3995         /* Otherwise, check everyone else. */
 3996         if (file_mode & S_IXOTH)
 3997                 dac_granted |= VEXEC;
 3998         if (file_mode & S_IROTH)
 3999                 dac_granted |= VREAD;
 4000         if (file_mode & S_IWOTH)
 4001                 dac_granted |= (VWRITE | VAPPEND);
 4002         if ((accmode & dac_granted) == accmode)
 4003                 return (0);
 4004 
 4005 privcheck:
 4006         /*
 4007          * Build a privilege mask to determine if the set of privileges
 4008          * satisfies the requirements when combined with the granted mask
 4009          * from above.  For each privilege, if the privilege is required,
 4010          * bitwise or the request type onto the priv_granted mask.
 4011          */
 4012         priv_granted = 0;
 4013 
 4014         if (type == VDIR) {
 4015                 /*
 4016                  * For directories, use PRIV_VFS_LOOKUP to satisfy VEXEC
 4017                  * requests, instead of PRIV_VFS_EXEC.
 4018                  */
 4019                 if ((accmode & VEXEC) && ((dac_granted & VEXEC) == 0) &&
 4020                     !priv_check_cred(cred, PRIV_VFS_LOOKUP, 0))
 4021                         priv_granted |= VEXEC;
 4022         } else {
 4023                 /*
 4024                  * Ensure that at least one execute bit is on. Otherwise,
 4025                  * a privileged user will always succeed, and we don't want
 4026                  * this to happen unless the file really is executable.
 4027                  */
 4028                 if ((accmode & VEXEC) && ((dac_granted & VEXEC) == 0) &&
 4029                     (file_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) != 0 &&
 4030                     !priv_check_cred(cred, PRIV_VFS_EXEC, 0))
 4031                         priv_granted |= VEXEC;
 4032         }
 4033 
 4034         if ((accmode & VREAD) && ((dac_granted & VREAD) == 0) &&
 4035             !priv_check_cred(cred, PRIV_VFS_READ, 0))
 4036                 priv_granted |= VREAD;
 4037 
 4038         if ((accmode & VWRITE) && ((dac_granted & VWRITE) == 0) &&
 4039             !priv_check_cred(cred, PRIV_VFS_WRITE, 0))
 4040                 priv_granted |= (VWRITE | VAPPEND);
 4041 
 4042         if ((accmode & VADMIN) && ((dac_granted & VADMIN) == 0) &&
 4043             !priv_check_cred(cred, PRIV_VFS_ADMIN, 0))
 4044                 priv_granted |= VADMIN;
 4045 
 4046         if ((accmode & (priv_granted | dac_granted)) == accmode) {
 4047                 /* XXX audit: privilege used */
 4048                 if (privused != NULL)
 4049                         *privused = 1;
 4050                 return (0);
 4051         }
 4052 
 4053         return ((accmode & VADMIN) ? EPERM : EACCES);
 4054 }
 4055 
 4056 /*
 4057  * Credential check based on process requesting service, and per-attribute
 4058  * permissions.
 4059  */
 4060 int
 4061 extattr_check_cred(struct vnode *vp, int attrnamespace, struct ucred *cred,
 4062     struct thread *td, accmode_t accmode)
 4063 {
 4064 
 4065         /*
 4066          * Kernel-invoked always succeeds.
 4067          */
 4068         if (cred == NOCRED)
 4069                 return (0);
 4070 
 4071         /*
 4072          * Do not allow privileged processes in jail to directly manipulate
 4073          * system attributes.
 4074          */
 4075         switch (attrnamespace) {
 4076         case EXTATTR_NAMESPACE_SYSTEM:
 4077                 /* Potentially should be: return (EPERM); */
 4078                 return (priv_check_cred(cred, PRIV_VFS_EXTATTR_SYSTEM, 0));
 4079         case EXTATTR_NAMESPACE_USER:
 4080                 return (VOP_ACCESS(vp, accmode, cred, td));
 4081         default:
 4082                 return (EPERM);
 4083         }
 4084 }
 4085 
 4086 #ifdef DEBUG_VFS_LOCKS
 4087 /*
 4088  * This only exists to suppress warnings from unlocked specfs accesses.  It is
 4089  * no longer ok to have an unlocked VFS.
 4090  */
 4091 #define IGNORE_LOCK(vp) (panicstr != NULL || (vp) == NULL ||            \
 4092         (vp)->v_type == VCHR || (vp)->v_type == VBAD)
 4093 
 4094 int vfs_badlock_ddb = 1;        /* Drop into debugger on violation. */
 4095 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_ddb, CTLFLAG_RW, &vfs_badlock_ddb, 0,
 4096     "Drop into debugger on lock violation");
 4097 
 4098 int vfs_badlock_mutex = 1;      /* Check for interlock across VOPs. */
 4099 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_mutex, CTLFLAG_RW, &vfs_badlock_mutex,
 4100     0, "Check for interlock across VOPs");
 4101 
 4102 int vfs_badlock_print = 1;      /* Print lock violations. */
 4103 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_print, CTLFLAG_RW, &vfs_badlock_print,
 4104     0, "Print lock violations");
 4105 
 4106 #ifdef KDB
 4107 int vfs_badlock_backtrace = 1;  /* Print backtrace at lock violations. */
 4108 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_backtrace, CTLFLAG_RW,
 4109     &vfs_badlock_backtrace, 0, "Print backtrace at lock violations");
 4110 #endif
 4111 
 4112 static void
 4113 vfs_badlock(const char *msg, const char *str, struct vnode *vp)
 4114 {
 4115 
 4116 #ifdef KDB
 4117         if (vfs_badlock_backtrace)
 4118                 kdb_backtrace();
 4119 #endif
 4120         if (vfs_badlock_print)
 4121                 printf("%s: %p %s\n", str, (void *)vp, msg);
 4122         if (vfs_badlock_ddb)
 4123                 kdb_enter(KDB_WHY_VFSLOCK, "lock violation");
 4124 }
 4125 
 4126 void
 4127 assert_vi_locked(struct vnode *vp, const char *str)
 4128 {
 4129 
 4130         if (vfs_badlock_mutex && !mtx_owned(VI_MTX(vp)))
 4131                 vfs_badlock("interlock is not locked but should be", str, vp);
 4132 }
 4133 
 4134 void
 4135 assert_vi_unlocked(struct vnode *vp, const char *str)
 4136 {
 4137 
 4138         if (vfs_badlock_mutex && mtx_owned(VI_MTX(vp)))
 4139                 vfs_badlock("interlock is locked but should not be", str, vp);
 4140 }
 4141 
 4142 void
 4143 assert_vop_locked(struct vnode *vp, const char *str)
 4144 {
 4145         int locked;
 4146 
 4147         if (!IGNORE_LOCK(vp)) {
 4148                 locked = VOP_ISLOCKED(vp);
 4149                 if (locked == 0 || locked == LK_EXCLOTHER)
 4150                         vfs_badlock("is not locked but should be", str, vp);
 4151         }
 4152 }
 4153 
 4154 void
 4155 assert_vop_unlocked(struct vnode *vp, const char *str)
 4156 {
 4157 
 4158         if (!IGNORE_LOCK(vp) && VOP_ISLOCKED(vp) == LK_EXCLUSIVE)
 4159                 vfs_badlock("is locked but should not be", str, vp);
 4160 }
 4161 
 4162 void
 4163 assert_vop_elocked(struct vnode *vp, const char *str)
 4164 {
 4165 
 4166         if (!IGNORE_LOCK(vp) && VOP_ISLOCKED(vp) != LK_EXCLUSIVE)
 4167                 vfs_badlock("is not exclusive locked but should be", str, vp);
 4168 }
 4169 
 4170 #if 0
 4171 void
 4172 assert_vop_elocked_other(struct vnode *vp, const char *str)
 4173 {
 4174 
 4175         if (!IGNORE_LOCK(vp) && VOP_ISLOCKED(vp) != LK_EXCLOTHER)
 4176                 vfs_badlock("is not exclusive locked by another thread",
 4177                     str, vp);
 4178 }
 4179 
 4180 void
 4181 assert_vop_slocked(struct vnode *vp, const char *str)
 4182 {
 4183 
 4184         if (!IGNORE_LOCK(vp) && VOP_ISLOCKED(vp) != LK_SHARED)
 4185                 vfs_badlock("is not locked shared but should be", str, vp);
 4186 }
 4187 #endif /* 0 */
 4188 #endif /* DEBUG_VFS_LOCKS */
 4189 
 4190 void
 4191 vop_rename_fail(struct vop_rename_args *ap)
 4192 {
 4193 
 4194         if (ap->a_tvp != NULL)
 4195                 vput(ap->a_tvp);
 4196         if (ap->a_tdvp == ap->a_tvp)
 4197                 vrele(ap->a_tdvp);
 4198         else
 4199                 vput(ap->a_tdvp);
 4200         vrele(ap->a_fdvp);
 4201         vrele(ap->a_fvp);
 4202 }
 4203 
 4204 void
 4205 vop_rename_pre(void *ap)
 4206 {
 4207         struct vop_rename_args *a = ap;
 4208 
 4209 #ifdef DEBUG_VFS_LOCKS
 4210         if (a->a_tvp)
 4211                 ASSERT_VI_UNLOCKED(a->a_tvp, "VOP_RENAME");
 4212         ASSERT_VI_UNLOCKED(a->a_tdvp, "VOP_RENAME");
 4213         ASSERT_VI_UNLOCKED(a->a_fvp, "VOP_RENAME");
 4214         ASSERT_VI_UNLOCKED(a->a_fdvp, "VOP_RENAME");
 4215 
 4216         /* Check the source (from). */
 4217         if (a->a_tdvp->v_vnlock != a->a_fdvp->v_vnlock &&
 4218             (a->a_tvp == NULL || a->a_tvp->v_vnlock != a->a_fdvp->v_vnlock))
 4219                 ASSERT_VOP_UNLOCKED(a->a_fdvp, "vop_rename: fdvp locked");
 4220         if (a->a_tvp == NULL || a->a_tvp->v_vnlock != a->a_fvp->v_vnlock)
 4221                 ASSERT_VOP_UNLOCKED(a->a_fvp, "vop_rename: fvp locked");
 4222 
 4223         /* Check the target. */
 4224         if (a->a_tvp)
 4225                 ASSERT_VOP_LOCKED(a->a_tvp, "vop_rename: tvp not locked");
 4226         ASSERT_VOP_LOCKED(a->a_tdvp, "vop_rename: tdvp not locked");
 4227 #endif
 4228         if (a->a_tdvp != a->a_fdvp)
 4229                 vhold(a->a_fdvp);
 4230         if (a->a_tvp != a->a_fvp)
 4231                 vhold(a->a_fvp);
 4232         vhold(a->a_tdvp);
 4233         if (a->a_tvp)
 4234                 vhold(a->a_tvp);
 4235 }
 4236 
 4237 void
 4238 vop_strategy_pre(void *ap)
 4239 {
 4240 #ifdef DEBUG_VFS_LOCKS
 4241         struct vop_strategy_args *a;
 4242         struct buf *bp;
 4243 
 4244         a = ap;
 4245         bp = a->a_bp;
 4246 
 4247         /*
 4248          * Cluster ops lock their component buffers but not the IO container.
 4249          */
 4250         if ((bp->b_flags & B_CLUSTER) != 0)
 4251                 return;
 4252 
 4253         if (panicstr == NULL && !BUF_ISLOCKED(bp)) {
 4254                 if (vfs_badlock_print)
 4255                         printf(
 4256                             "VOP_STRATEGY: bp is not locked but should be\n");
 4257                 if (vfs_badlock_ddb)
 4258                         kdb_enter(KDB_WHY_VFSLOCK, "lock violation");
 4259         }
 4260 #endif
 4261 }
 4262 
 4263 void
 4264 vop_lock_pre(void *ap)
 4265 {
 4266 #ifdef DEBUG_VFS_LOCKS
 4267         struct vop_lock1_args *a = ap;
 4268 
 4269         if ((a->a_flags & LK_INTERLOCK) == 0)
 4270                 ASSERT_VI_UNLOCKED(a->a_vp, "VOP_LOCK");
 4271         else
 4272                 ASSERT_VI_LOCKED(a->a_vp, "VOP_LOCK");
 4273 #endif
 4274 }
 4275 
 4276 void
 4277 vop_lock_post(void *ap, int rc)
 4278 {
 4279 #ifdef DEBUG_VFS_LOCKS
 4280         struct vop_lock1_args *a = ap;
 4281 
 4282         ASSERT_VI_UNLOCKED(a->a_vp, "VOP_LOCK");
 4283         if (rc == 0 && (a->a_flags & LK_EXCLOTHER) == 0)
 4284                 ASSERT_VOP_LOCKED(a->a_vp, "VOP_LOCK");
 4285 #endif
 4286 }
 4287 
 4288 void
 4289 vop_unlock_pre(void *ap)
 4290 {
 4291 #ifdef DEBUG_VFS_LOCKS
 4292         struct vop_unlock_args *a = ap;
 4293 
 4294         if (a->a_flags & LK_INTERLOCK)
 4295                 ASSERT_VI_LOCKED(a->a_vp, "VOP_UNLOCK");
 4296         ASSERT_VOP_LOCKED(a->a_vp, "VOP_UNLOCK");
 4297 #endif
 4298 }
 4299 
 4300 void
 4301 vop_unlock_post(void *ap, int rc)
 4302 {
 4303 #ifdef DEBUG_VFS_LOCKS
 4304         struct vop_unlock_args *a = ap;
 4305 
 4306         if (a->a_flags & LK_INTERLOCK)
 4307                 ASSERT_VI_UNLOCKED(a->a_vp, "VOP_UNLOCK");
 4308 #endif
 4309 }
 4310 
 4311 void
 4312 vop_create_post(void *ap, int rc)
 4313 {
 4314         struct vop_create_args *a = ap;
 4315 
 4316         if (!rc)
 4317                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 4318 }
 4319 
 4320 void
 4321 vop_deleteextattr_post(void *ap, int rc)
 4322 {
 4323         struct vop_deleteextattr_args *a = ap;
 4324 
 4325         if (!rc)
 4326                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_ATTRIB);
 4327 }
 4328 
 4329 void
 4330 vop_link_post(void *ap, int rc)
 4331 {
 4332         struct vop_link_args *a = ap;
 4333 
 4334         if (!rc) {
 4335                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_LINK);
 4336                 VFS_KNOTE_LOCKED(a->a_tdvp, NOTE_WRITE);
 4337         }
 4338 }
 4339 
 4340 void
 4341 vop_mkdir_post(void *ap, int rc)
 4342 {
 4343         struct vop_mkdir_args *a = ap;
 4344 
 4345         if (!rc)
 4346                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE | NOTE_LINK);
 4347 }
 4348 
 4349 void
 4350 vop_mknod_post(void *ap, int rc)
 4351 {
 4352         struct vop_mknod_args *a = ap;
 4353 
 4354         if (!rc)
 4355                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 4356 }
 4357 
 4358 void
 4359 vop_reclaim_post(void *ap, int rc)
 4360 {
 4361         struct vop_reclaim_args *a = ap;
 4362 
 4363         if (!rc)
 4364                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_REVOKE);
 4365 }
 4366 
 4367 void
 4368 vop_remove_post(void *ap, int rc)
 4369 {
 4370         struct vop_remove_args *a = ap;
 4371 
 4372         if (!rc) {
 4373                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 4374                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_DELETE);
 4375         }
 4376 }
 4377 
 4378 void
 4379 vop_rename_post(void *ap, int rc)
 4380 {
 4381         struct vop_rename_args *a = ap;
 4382         long hint;
 4383 
 4384         if (!rc) {
 4385                 hint = NOTE_WRITE;
 4386                 if (a->a_fdvp == a->a_tdvp) {
 4387                         if (a->a_tvp != NULL && a->a_tvp->v_type == VDIR)
 4388                                 hint |= NOTE_LINK;
 4389                         VFS_KNOTE_UNLOCKED(a->a_fdvp, hint);
 4390                         VFS_KNOTE_UNLOCKED(a->a_tdvp, hint);
 4391                 } else {
 4392                         hint |= NOTE_EXTEND;
 4393                         if (a->a_fvp->v_type == VDIR)
 4394                                 hint |= NOTE_LINK;
 4395                         VFS_KNOTE_UNLOCKED(a->a_fdvp, hint);
 4396 
 4397                         if (a->a_fvp->v_type == VDIR && a->a_tvp != NULL &&
 4398                             a->a_tvp->v_type == VDIR)
 4399                                 hint &= ~NOTE_LINK;
 4400                         VFS_KNOTE_UNLOCKED(a->a_tdvp, hint);
 4401                 }
 4402 
 4403                 VFS_KNOTE_UNLOCKED(a->a_fvp, NOTE_RENAME);
 4404                 if (a->a_tvp)
 4405                         VFS_KNOTE_UNLOCKED(a->a_tvp, NOTE_DELETE);
 4406         }
 4407         if (a->a_tdvp != a->a_fdvp)
 4408                 vdrop(a->a_fdvp);
 4409         if (a->a_tvp != a->a_fvp)
 4410                 vdrop(a->a_fvp);
 4411         vdrop(a->a_tdvp);
 4412         if (a->a_tvp)
 4413                 vdrop(a->a_tvp);
 4414 }
 4415 
 4416 void
 4417 vop_rmdir_post(void *ap, int rc)
 4418 {
 4419         struct vop_rmdir_args *a = ap;
 4420 
 4421         if (!rc) {
 4422                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE | NOTE_LINK);
 4423                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_DELETE);
 4424         }
 4425 }
 4426 
 4427 void
 4428 vop_setattr_post(void *ap, int rc)
 4429 {
 4430         struct vop_setattr_args *a = ap;
 4431 
 4432         if (!rc)
 4433                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_ATTRIB);
 4434 }
 4435 
 4436 void
 4437 vop_setextattr_post(void *ap, int rc)
 4438 {
 4439         struct vop_setextattr_args *a = ap;
 4440 
 4441         if (!rc)
 4442                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_ATTRIB);
 4443 }
 4444 
 4445 void
 4446 vop_symlink_post(void *ap, int rc)
 4447 {
 4448         struct vop_symlink_args *a = ap;
 4449 
 4450         if (!rc)
 4451                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 4452 }
 4453 
 4454 void
 4455 vop_open_post(void *ap, int rc)
 4456 {
 4457         struct vop_open_args *a = ap;
 4458 
 4459         if (!rc)
 4460                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_OPEN);
 4461 }
 4462 
 4463 void
 4464 vop_close_post(void *ap, int rc)
 4465 {
 4466         struct vop_close_args *a = ap;
 4467 
 4468         if (!rc && (a->a_cred != NOCRED || /* filter out revokes */
 4469             (a->a_vp->v_iflag & VI_DOOMED) == 0)) {
 4470                 VFS_KNOTE_LOCKED(a->a_vp, (a->a_fflag & FWRITE) != 0 ?
 4471                     NOTE_CLOSE_WRITE : NOTE_CLOSE);
 4472         }
 4473 }
 4474 
 4475 void
 4476 vop_read_post(void *ap, int rc)
 4477 {
 4478         struct vop_read_args *a = ap;
 4479 
 4480         if (!rc)
 4481                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_READ);
 4482 }
 4483 
 4484 void
 4485 vop_readdir_post(void *ap, int rc)
 4486 {
 4487         struct vop_readdir_args *a = ap;
 4488 
 4489         if (!rc)
 4490                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_READ);
 4491 }
 4492 
 4493 static struct knlist fs_knlist;
 4494 
 4495 static void
 4496 vfs_event_init(void *arg)
 4497 {
 4498         knlist_init_mtx(&fs_knlist, NULL);
 4499 }
 4500 /* XXX - correct order? */
 4501 SYSINIT(vfs_knlist, SI_SUB_VFS, SI_ORDER_ANY, vfs_event_init, NULL);
 4502 
 4503 void
 4504 vfs_event_signal(fsid_t *fsid, uint32_t event, intptr_t data __unused)
 4505 {
 4506 
 4507         KNOTE_UNLOCKED(&fs_knlist, event);
 4508 }
 4509 
 4510 static int      filt_fsattach(struct knote *kn);
 4511 static void     filt_fsdetach(struct knote *kn);
 4512 static int      filt_fsevent(struct knote *kn, long hint);
 4513 
 4514 struct filterops fs_filtops = {
 4515         .f_isfd = 0,
 4516         .f_attach = filt_fsattach,
 4517         .f_detach = filt_fsdetach,
 4518         .f_event = filt_fsevent
 4519 };
 4520 
 4521 static int
 4522 filt_fsattach(struct knote *kn)
 4523 {
 4524 
 4525         kn->kn_flags |= EV_CLEAR;
 4526         knlist_add(&fs_knlist, kn, 0);
 4527         return (0);
 4528 }
 4529 
 4530 static void
 4531 filt_fsdetach(struct knote *kn)
 4532 {
 4533 
 4534         knlist_remove(&fs_knlist, kn, 0);
 4535 }
 4536 
 4537 static int
 4538 filt_fsevent(struct knote *kn, long hint)
 4539 {
 4540 
 4541         kn->kn_fflags |= hint;
 4542         return (kn->kn_fflags != 0);
 4543 }
 4544 
 4545 static int
 4546 sysctl_vfs_ctl(SYSCTL_HANDLER_ARGS)
 4547 {
 4548         struct vfsidctl vc;
 4549         int error;
 4550         struct mount *mp;
 4551 
 4552         error = SYSCTL_IN(req, &vc, sizeof(vc));
 4553         if (error)
 4554                 return (error);
 4555         if (vc.vc_vers != VFS_CTL_VERS1)
 4556                 return (EINVAL);
 4557         mp = vfs_getvfs(&vc.vc_fsid);
 4558         if (mp == NULL)
 4559                 return (ENOENT);
 4560         /* ensure that a specific sysctl goes to the right filesystem. */
 4561         if (strcmp(vc.vc_fstypename, "*") != 0 &&
 4562             strcmp(vc.vc_fstypename, mp->mnt_vfc->vfc_name) != 0) {
 4563                 vfs_rel(mp);
 4564                 return (EINVAL);
 4565         }
 4566         VCTLTOREQ(&vc, req);
 4567         error = VFS_SYSCTL(mp, vc.vc_op, req);
 4568         vfs_rel(mp);
 4569         return (error);
 4570 }
 4571 
 4572 SYSCTL_PROC(_vfs, OID_AUTO, ctl, CTLTYPE_OPAQUE | CTLFLAG_WR,
 4573     NULL, 0, sysctl_vfs_ctl, "",
 4574     "Sysctl by fsid");
 4575 
 4576 /*
 4577  * Function to initialize a va_filerev field sensibly.
 4578  * XXX: Wouldn't a random number make a lot more sense ??
 4579  */
 4580 u_quad_t
 4581 init_va_filerev(void)
 4582 {
 4583         struct bintime bt;
 4584 
 4585         getbinuptime(&bt);
 4586         return (((u_quad_t)bt.sec << 32LL) | (bt.frac >> 32LL));
 4587 }
 4588 
 4589 static int      filt_vfsread(struct knote *kn, long hint);
 4590 static int      filt_vfswrite(struct knote *kn, long hint);
 4591 static int      filt_vfsvnode(struct knote *kn, long hint);
 4592 static void     filt_vfsdetach(struct knote *kn);
 4593 static struct filterops vfsread_filtops = {
 4594         .f_isfd = 1,
 4595         .f_detach = filt_vfsdetach,
 4596         .f_event = filt_vfsread
 4597 };
 4598 static struct filterops vfswrite_filtops = {
 4599         .f_isfd = 1,
 4600         .f_detach = filt_vfsdetach,
 4601         .f_event = filt_vfswrite
 4602 };
 4603 static struct filterops vfsvnode_filtops = {
 4604         .f_isfd = 1,
 4605         .f_detach = filt_vfsdetach,
 4606         .f_event = filt_vfsvnode
 4607 };
 4608 
 4609 static void
 4610 vfs_knllock(void *arg)
 4611 {
 4612         struct vnode *vp = arg;
 4613 
 4614         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 4615 }
 4616 
 4617 static void
 4618 vfs_knlunlock(void *arg)
 4619 {
 4620         struct vnode *vp = arg;
 4621 
 4622         VOP_UNLOCK(vp, 0);
 4623 }
 4624 
 4625 static void
 4626 vfs_knl_assert_locked(void *arg)
 4627 {
 4628 #ifdef DEBUG_VFS_LOCKS
 4629         struct vnode *vp = arg;
 4630 
 4631         ASSERT_VOP_LOCKED(vp, "vfs_knl_assert_locked");
 4632 #endif
 4633 }
 4634 
 4635 static void
 4636 vfs_knl_assert_unlocked(void *arg)
 4637 {
 4638 #ifdef DEBUG_VFS_LOCKS
 4639         struct vnode *vp = arg;
 4640 
 4641         ASSERT_VOP_UNLOCKED(vp, "vfs_knl_assert_unlocked");
 4642 #endif
 4643 }
 4644 
 4645 int
 4646 vfs_kqfilter(struct vop_kqfilter_args *ap)
 4647 {
 4648         struct vnode *vp = ap->a_vp;
 4649         struct knote *kn = ap->a_kn;
 4650         struct knlist *knl;
 4651 
 4652         switch (kn->kn_filter) {
 4653         case EVFILT_READ:
 4654                 kn->kn_fop = &vfsread_filtops;
 4655                 break;
 4656         case EVFILT_WRITE:
 4657                 kn->kn_fop = &vfswrite_filtops;
 4658                 break;
 4659         case EVFILT_VNODE:
 4660                 kn->kn_fop = &vfsvnode_filtops;
 4661                 break;
 4662         default:
 4663                 return (EINVAL);
 4664         }
 4665 
 4666         kn->kn_hook = (caddr_t)vp;
 4667 
 4668         v_addpollinfo(vp);
 4669         if (vp->v_pollinfo == NULL)
 4670                 return (ENOMEM);
 4671         knl = &vp->v_pollinfo->vpi_selinfo.si_note;
 4672         vhold(vp);
 4673         knlist_add(knl, kn, 0);
 4674 
 4675         return (0);
 4676 }
 4677 
 4678 /*
 4679  * Detach knote from vnode
 4680  */
 4681 static void
 4682 filt_vfsdetach(struct knote *kn)
 4683 {
 4684         struct vnode *vp = (struct vnode *)kn->kn_hook;
 4685 
 4686         KASSERT(vp->v_pollinfo != NULL, ("Missing v_pollinfo"));
 4687         knlist_remove(&vp->v_pollinfo->vpi_selinfo.si_note, kn, 0);
 4688         vdrop(vp);
 4689 }
 4690 
 4691 /*ARGSUSED*/
 4692 static int
 4693 filt_vfsread(struct knote *kn, long hint)
 4694 {
 4695         struct vnode *vp = (struct vnode *)kn->kn_hook;
 4696         struct vattr va;
 4697         int res;
 4698 
 4699         /*
 4700          * filesystem is gone, so set the EOF flag and schedule
 4701          * the knote for deletion.
 4702          */
 4703         if (hint == NOTE_REVOKE || (hint == 0 && vp->v_type == VBAD)) {
 4704                 VI_LOCK(vp);
 4705                 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 4706                 VI_UNLOCK(vp);
 4707                 return (1);
 4708         }
 4709 
 4710         if (VOP_GETATTR(vp, &va, curthread->td_ucred))
 4711                 return (0);
 4712 
 4713         VI_LOCK(vp);
 4714         kn->kn_data = va.va_size - kn->kn_fp->f_offset;
 4715         res = (kn->kn_data != 0);
 4716         VI_UNLOCK(vp);
 4717         return (res);
 4718 }
 4719 
 4720 /*ARGSUSED*/
 4721 static int
 4722 filt_vfswrite(struct knote *kn, long hint)
 4723 {
 4724         struct vnode *vp = (struct vnode *)kn->kn_hook;
 4725 
 4726         VI_LOCK(vp);
 4727 
 4728         /*
 4729          * filesystem is gone, so set the EOF flag and schedule
 4730          * the knote for deletion.
 4731          */
 4732         if (hint == NOTE_REVOKE || (hint == 0 && vp->v_type == VBAD))
 4733                 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 4734 
 4735         kn->kn_data = 0;
 4736         VI_UNLOCK(vp);
 4737         return (1);
 4738 }
 4739 
 4740 static int
 4741 filt_vfsvnode(struct knote *kn, long hint)
 4742 {
 4743         struct vnode *vp = (struct vnode *)kn->kn_hook;
 4744         int res;
 4745 
 4746         VI_LOCK(vp);
 4747         if (kn->kn_sfflags & hint)
 4748                 kn->kn_fflags |= hint;
 4749         if (hint == NOTE_REVOKE || (hint == 0 && vp->v_type == VBAD)) {
 4750                 kn->kn_flags |= EV_EOF;
 4751                 VI_UNLOCK(vp);
 4752                 return (1);
 4753         }
 4754         res = (kn->kn_fflags != 0);
 4755         VI_UNLOCK(vp);
 4756         return (res);
 4757 }
 4758 
 4759 int
 4760 vfs_read_dirent(struct vop_readdir_args *ap, struct dirent *dp, off_t off)
 4761 {
 4762         int error;
 4763 
 4764         if (dp->d_reclen > ap->a_uio->uio_resid)
 4765                 return (ENAMETOOLONG);
 4766         error = uiomove(dp, dp->d_reclen, ap->a_uio);
 4767         if (error) {
 4768                 if (ap->a_ncookies != NULL) {
 4769                         if (ap->a_cookies != NULL)
 4770                                 free(ap->a_cookies, M_TEMP);
 4771                         ap->a_cookies = NULL;
 4772                         *ap->a_ncookies = 0;
 4773                 }
 4774                 return (error);
 4775         }
 4776         if (ap->a_ncookies == NULL)
 4777                 return (0);
 4778 
 4779         KASSERT(ap->a_cookies,
 4780             ("NULL ap->a_cookies value with non-NULL ap->a_ncookies!"));
 4781 
 4782         *ap->a_cookies = realloc(*ap->a_cookies,
 4783             (*ap->a_ncookies + 1) * sizeof(u_long), M_TEMP, M_WAITOK | M_ZERO);
 4784         (*ap->a_cookies)[*ap->a_ncookies] = off;
 4785         *ap->a_ncookies += 1;
 4786         return (0);
 4787 }
 4788 
 4789 /*
 4790  * Mark for update the access time of the file if the filesystem
 4791  * supports VOP_MARKATIME.  This functionality is used by execve and
 4792  * mmap, so we want to avoid the I/O implied by directly setting
 4793  * va_atime for the sake of efficiency.
 4794  */
 4795 void
 4796 vfs_mark_atime(struct vnode *vp, struct ucred *cred)
 4797 {
 4798         struct mount *mp;
 4799 
 4800         mp = vp->v_mount;
 4801         ASSERT_VOP_LOCKED(vp, "vfs_mark_atime");
 4802         if (mp != NULL && (mp->mnt_flag & (MNT_NOATIME | MNT_RDONLY)) == 0)
 4803                 (void)VOP_MARKATIME(vp);
 4804 }
 4805 
 4806 /*
 4807  * The purpose of this routine is to remove granularity from accmode_t,
 4808  * reducing it into standard unix access bits - VEXEC, VREAD, VWRITE,
 4809  * VADMIN and VAPPEND.
 4810  *
 4811  * If it returns 0, the caller is supposed to continue with the usual
 4812  * access checks using 'accmode' as modified by this routine.  If it
 4813  * returns nonzero value, the caller is supposed to return that value
 4814  * as errno.
 4815  *
 4816  * Note that after this routine runs, accmode may be zero.
 4817  */
 4818 int
 4819 vfs_unixify_accmode(accmode_t *accmode)
 4820 {
 4821         /*
 4822          * There is no way to specify explicit "deny" rule using
 4823          * file mode or POSIX.1e ACLs.
 4824          */
 4825         if (*accmode & VEXPLICIT_DENY) {
 4826                 *accmode = 0;
 4827                 return (0);
 4828         }
 4829 
 4830         /*
 4831          * None of these can be translated into usual access bits.
 4832          * Also, the common case for NFSv4 ACLs is to not contain
 4833          * either of these bits. Caller should check for VWRITE
 4834          * on the containing directory instead.
 4835          */
 4836         if (*accmode & (VDELETE_CHILD | VDELETE))
 4837                 return (EPERM);
 4838 
 4839         if (*accmode & VADMIN_PERMS) {
 4840                 *accmode &= ~VADMIN_PERMS;
 4841                 *accmode |= VADMIN;
 4842         }
 4843 
 4844         /*
 4845          * There is no way to deny VREAD_ATTRIBUTES, VREAD_ACL
 4846          * or VSYNCHRONIZE using file mode or POSIX.1e ACL.
 4847          */
 4848         *accmode &= ~(VSTAT_PERMS | VSYNCHRONIZE);
 4849 
 4850         return (0);
 4851 }
 4852 
 4853 /*
 4854  * These are helper functions for filesystems to traverse all
 4855  * their vnodes.  See MNT_VNODE_FOREACH_ALL() in sys/mount.h.
 4856  *
 4857  * This interface replaces MNT_VNODE_FOREACH.
 4858  */
 4859 
 4860 MALLOC_DEFINE(M_VNODE_MARKER, "vnodemarker", "vnode marker");
 4861 
 4862 struct vnode *
 4863 __mnt_vnode_next_all(struct vnode **mvp, struct mount *mp)
 4864 {
 4865         struct vnode *vp;
 4866 
 4867         if (should_yield())
 4868                 kern_yield(PRI_USER);
 4869         MNT_ILOCK(mp);
 4870         KASSERT((*mvp)->v_mount == mp, ("marker vnode mount list mismatch"));
 4871         vp = TAILQ_NEXT(*mvp, v_nmntvnodes);
 4872         while (vp != NULL && (vp->v_type == VMARKER ||
 4873             (vp->v_iflag & VI_DOOMED) != 0))
 4874                 vp = TAILQ_NEXT(vp, v_nmntvnodes);
 4875 
 4876         /* Check if we are done */
 4877         if (vp == NULL) {
 4878                 __mnt_vnode_markerfree_all(mvp, mp);
 4879                 /* MNT_IUNLOCK(mp); -- done in above function */
 4880                 mtx_assert(MNT_MTX(mp), MA_NOTOWNED);
 4881                 return (NULL);
 4882         }
 4883         TAILQ_REMOVE(&mp->mnt_nvnodelist, *mvp, v_nmntvnodes);
 4884         TAILQ_INSERT_AFTER(&mp->mnt_nvnodelist, vp, *mvp, v_nmntvnodes);
 4885         VI_LOCK(vp);
 4886         MNT_IUNLOCK(mp);
 4887         return (vp);
 4888 }
 4889 
 4890 struct vnode *
 4891 __mnt_vnode_first_all(struct vnode **mvp, struct mount *mp)
 4892 {
 4893         struct vnode *vp;
 4894 
 4895         *mvp = malloc(sizeof(struct vnode), M_VNODE_MARKER, M_WAITOK | M_ZERO);
 4896         MNT_ILOCK(mp);
 4897         MNT_REF(mp);
 4898         (*mvp)->v_type = VMARKER;
 4899 
 4900         vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
 4901         while (vp != NULL && (vp->v_type == VMARKER ||
 4902             (vp->v_iflag & VI_DOOMED) != 0))
 4903                 vp = TAILQ_NEXT(vp, v_nmntvnodes);
 4904 
 4905         /* Check if we are done */
 4906         if (vp == NULL) {
 4907                 MNT_REL(mp);
 4908                 MNT_IUNLOCK(mp);
 4909                 free(*mvp, M_VNODE_MARKER);
 4910                 *mvp = NULL;
 4911                 return (NULL);
 4912         }
 4913         (*mvp)->v_mount = mp;
 4914         TAILQ_INSERT_AFTER(&mp->mnt_nvnodelist, vp, *mvp, v_nmntvnodes);
 4915         VI_LOCK(vp);
 4916         MNT_IUNLOCK(mp);
 4917         return (vp);
 4918 }
 4919 
 4920 
 4921 void
 4922 __mnt_vnode_markerfree_all(struct vnode **mvp, struct mount *mp)
 4923 {
 4924 
 4925         if (*mvp == NULL) {
 4926                 MNT_IUNLOCK(mp);
 4927                 return;
 4928         }
 4929 
 4930         mtx_assert(MNT_MTX(mp), MA_OWNED);
 4931 
 4932         KASSERT((*mvp)->v_mount == mp, ("marker vnode mount list mismatch"));
 4933         TAILQ_REMOVE(&mp->mnt_nvnodelist, *mvp, v_nmntvnodes);
 4934         MNT_REL(mp);
 4935         MNT_IUNLOCK(mp);
 4936         free(*mvp, M_VNODE_MARKER);
 4937         *mvp = NULL;
 4938 }
 4939 
 4940 /*
 4941  * These are helper functions for filesystems to traverse their
 4942  * active vnodes.  See MNT_VNODE_FOREACH_ACTIVE() in sys/mount.h
 4943  */
 4944 static void
 4945 mnt_vnode_markerfree_active(struct vnode **mvp, struct mount *mp)
 4946 {
 4947 
 4948         KASSERT((*mvp)->v_mount == mp, ("marker vnode mount list mismatch"));
 4949 
 4950         MNT_ILOCK(mp);
 4951         MNT_REL(mp);
 4952         MNT_IUNLOCK(mp);
 4953         free(*mvp, M_VNODE_MARKER);
 4954         *mvp = NULL;
 4955 }
 4956 
 4957 static struct vnode *
 4958 mnt_vnode_next_active(struct vnode **mvp, struct mount *mp)
 4959 {
 4960         struct vnode *vp, *nvp;
 4961 
 4962         mtx_assert(&vnode_free_list_mtx, MA_OWNED);
 4963         KASSERT((*mvp)->v_mount == mp, ("marker vnode mount list mismatch"));
 4964 restart:
 4965         vp = TAILQ_NEXT(*mvp, v_actfreelist);
 4966         TAILQ_REMOVE(&mp->mnt_activevnodelist, *mvp, v_actfreelist);
 4967         while (vp != NULL) {
 4968                 if (vp->v_type == VMARKER) {
 4969                         vp = TAILQ_NEXT(vp, v_actfreelist);
 4970                         continue;
 4971                 }
 4972                 if (!VI_TRYLOCK(vp)) {
 4973                         if (mp_ncpus == 1 || should_yield()) {
 4974                                 TAILQ_INSERT_BEFORE(vp, *mvp, v_actfreelist);
 4975                                 mtx_unlock(&vnode_free_list_mtx);
 4976                                 pause("vnacti", 1);
 4977                                 mtx_lock(&vnode_free_list_mtx);
 4978                                 goto restart;
 4979                         }
 4980                         continue;
 4981                 }
 4982                 KASSERT(vp->v_type != VMARKER, ("locked marker %p", vp));
 4983                 KASSERT(vp->v_mount == mp || vp->v_mount == NULL,
 4984                     ("alien vnode on the active list %p %p", vp, mp));
 4985                 if (vp->v_mount == mp && (vp->v_iflag & VI_DOOMED) == 0)
 4986                         break;
 4987                 nvp = TAILQ_NEXT(vp, v_actfreelist);
 4988                 VI_UNLOCK(vp);
 4989                 vp = nvp;
 4990         }
 4991 
 4992         /* Check if we are done */
 4993         if (vp == NULL) {
 4994                 mtx_unlock(&vnode_free_list_mtx);
 4995                 mnt_vnode_markerfree_active(mvp, mp);
 4996                 return (NULL);
 4997         }
 4998         TAILQ_INSERT_AFTER(&mp->mnt_activevnodelist, vp, *mvp, v_actfreelist);
 4999         mtx_unlock(&vnode_free_list_mtx);
 5000         ASSERT_VI_LOCKED(vp, "active iter");
 5001         KASSERT((vp->v_iflag & VI_ACTIVE) != 0, ("Non-active vp %p", vp));
 5002         return (vp);
 5003 }
 5004 
 5005 struct vnode *
 5006 __mnt_vnode_next_active(struct vnode **mvp, struct mount *mp)
 5007 {
 5008 
 5009         if (should_yield())
 5010                 kern_yield(PRI_USER);
 5011         mtx_lock(&vnode_free_list_mtx);
 5012         return (mnt_vnode_next_active(mvp, mp));
 5013 }
 5014 
 5015 struct vnode *
 5016 __mnt_vnode_first_active(struct vnode **mvp, struct mount *mp)
 5017 {
 5018         struct vnode *vp;
 5019 
 5020         *mvp = malloc(sizeof(struct vnode), M_VNODE_MARKER, M_WAITOK | M_ZERO);
 5021         MNT_ILOCK(mp);
 5022         MNT_REF(mp);
 5023         MNT_IUNLOCK(mp);
 5024         (*mvp)->v_type = VMARKER;
 5025         (*mvp)->v_mount = mp;
 5026 
 5027         mtx_lock(&vnode_free_list_mtx);
 5028         vp = TAILQ_FIRST(&mp->mnt_activevnodelist);
 5029         if (vp == NULL) {
 5030                 mtx_unlock(&vnode_free_list_mtx);
 5031                 mnt_vnode_markerfree_active(mvp, mp);
 5032                 return (NULL);
 5033         }
 5034         TAILQ_INSERT_BEFORE(vp, *mvp, v_actfreelist);
 5035         return (mnt_vnode_next_active(mvp, mp));
 5036 }
 5037 
 5038 void
 5039 __mnt_vnode_markerfree_active(struct vnode **mvp, struct mount *mp)
 5040 {
 5041 
 5042         if (*mvp == NULL)
 5043                 return;
 5044 
 5045         mtx_lock(&vnode_free_list_mtx);
 5046         TAILQ_REMOVE(&mp->mnt_activevnodelist, *mvp, v_actfreelist);
 5047         mtx_unlock(&vnode_free_list_mtx);
 5048         mnt_vnode_markerfree_active(mvp, mp);
 5049 }

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