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("$FreeBSD$");
   43 
   44 #include "opt_ddb.h"
   45 #include "opt_mac.h"
   46 
   47 #include <sys/param.h>
   48 #include <sys/systm.h>
   49 #include <sys/bio.h>
   50 #include <sys/buf.h>
   51 #include <sys/conf.h>
   52 #include <sys/dirent.h>
   53 #include <sys/event.h>
   54 #include <sys/eventhandler.h>
   55 #include <sys/extattr.h>
   56 #include <sys/file.h>
   57 #include <sys/fcntl.h>
   58 #include <sys/jail.h>
   59 #include <sys/kdb.h>
   60 #include <sys/kernel.h>
   61 #include <sys/kthread.h>
   62 #include <sys/malloc.h>
   63 #include <sys/mount.h>
   64 #include <sys/namei.h>
   65 #include <sys/priv.h>
   66 #include <sys/reboot.h>
   67 #include <sys/sleepqueue.h>
   68 #include <sys/stat.h>
   69 #include <sys/sysctl.h>
   70 #include <sys/syslog.h>
   71 #include <sys/vmmeter.h>
   72 #include <sys/vnode.h>
   73 
   74 #include <machine/stdarg.h>
   75 
   76 #include <security/mac/mac_framework.h>
   77 
   78 #include <vm/vm.h>
   79 #include <vm/vm_object.h>
   80 #include <vm/vm_extern.h>
   81 #include <vm/pmap.h>
   82 #include <vm/vm_map.h>
   83 #include <vm/vm_page.h>
   84 #include <vm/vm_kern.h>
   85 #include <vm/uma.h>
   86 
   87 #ifdef DDB
   88 #include <ddb/ddb.h>
   89 #endif
   90 
   91 static MALLOC_DEFINE(M_NETADDR, "subr_export_host", "Export host address structure");
   92 
   93 static void     delmntque(struct vnode *vp);
   94 static int      flushbuflist(struct bufv *bufv, int flags, struct bufobj *bo,
   95                     int slpflag, int slptimeo);
   96 static void     syncer_shutdown(void *arg, int howto);
   97 static int      vtryrecycle(struct vnode *vp);
   98 static void     vbusy(struct vnode *vp);
   99 static void     vinactive(struct vnode *, struct thread *);
  100 static void     v_incr_usecount(struct vnode *);
  101 static void     v_decr_usecount(struct vnode *);
  102 static void     v_decr_useonly(struct vnode *);
  103 static void     v_upgrade_usecount(struct vnode *);
  104 static void     vfree(struct vnode *);
  105 static void     vnlru_free(int);
  106 static void     vdestroy(struct vnode *);
  107 static void     vgonel(struct vnode *);
  108 static void     vfs_knllock(void *arg);
  109 static void     vfs_knlunlock(void *arg);
  110 static int      vfs_knllocked(void *arg);
  111 
  112 
  113 /*
  114  * Enable Giant pushdown based on whether or not the vm is mpsafe in this
  115  * build.  Without mpsafevm the buffer cache can not run Giant free.
  116  */
  117 int mpsafe_vfs = 1;
  118 TUNABLE_INT("debug.mpsafevfs", &mpsafe_vfs);
  119 SYSCTL_INT(_debug, OID_AUTO, mpsafevfs, CTLFLAG_RD, &mpsafe_vfs, 0,
  120     "MPSAFE VFS");
  121 
  122 /*
  123  * Number of vnodes in existence.  Increased whenever getnewvnode()
  124  * allocates a new vnode, decreased on vdestroy() called on VI_DOOMed
  125  * vnode.
  126  */
  127 static unsigned long    numvnodes;
  128 
  129 SYSCTL_LONG(_vfs, OID_AUTO, numvnodes, CTLFLAG_RD, &numvnodes, 0, "");
  130 
  131 /*
  132  * Conversion tables for conversion from vnode types to inode formats
  133  * and back.
  134  */
  135 enum vtype iftovt_tab[16] = {
  136         VNON, VFIFO, VCHR, VNON, VDIR, VNON, VBLK, VNON,
  137         VREG, VNON, VLNK, VNON, VSOCK, VNON, VNON, VBAD,
  138 };
  139 int vttoif_tab[10] = {
  140         0, S_IFREG, S_IFDIR, S_IFBLK, S_IFCHR, S_IFLNK,
  141         S_IFSOCK, S_IFIFO, S_IFMT, S_IFMT
  142 };
  143 
  144 /*
  145  * List of vnodes that are ready for recycling.
  146  */
  147 static TAILQ_HEAD(freelst, vnode) vnode_free_list;
  148 
  149 /*
  150  * Free vnode target.  Free vnodes may simply be files which have been stat'd
  151  * but not read.  This is somewhat common, and a small cache of such files
  152  * should be kept to avoid recreation costs.
  153  */
  154 static u_long wantfreevnodes;
  155 SYSCTL_LONG(_vfs, OID_AUTO, wantfreevnodes, CTLFLAG_RW, &wantfreevnodes, 0, "");
  156 /* Number of vnodes in the free list. */
  157 static u_long freevnodes;
  158 SYSCTL_LONG(_vfs, OID_AUTO, freevnodes, CTLFLAG_RD, &freevnodes, 0, "");
  159 
  160 /*
  161  * Various variables used for debugging the new implementation of
  162  * reassignbuf().
  163  * XXX these are probably of (very) limited utility now.
  164  */
  165 static int reassignbufcalls;
  166 SYSCTL_INT(_vfs, OID_AUTO, reassignbufcalls, CTLFLAG_RW, &reassignbufcalls, 0, "");
  167 
  168 /*
  169  * Cache for the mount type id assigned to NFS.  This is used for
  170  * special checks in nfs/nfs_nqlease.c and vm/vnode_pager.c.
  171  */
  172 int     nfs_mount_type = -1;
  173 
  174 /* To keep more than one thread at a time from running vfs_getnewfsid */
  175 static struct mtx mntid_mtx;
  176 
  177 /*
  178  * Lock for any access to the following:
  179  *      vnode_free_list
  180  *      numvnodes
  181  *      freevnodes
  182  */
  183 static struct mtx vnode_free_list_mtx;
  184 
  185 /* Publicly exported FS */
  186 struct nfs_public nfs_pub;
  187 
  188 /* Zone for allocation of new vnodes - used exclusively by getnewvnode() */
  189 static uma_zone_t vnode_zone;
  190 static uma_zone_t vnodepoll_zone;
  191 
  192 /* Set to 1 to print out reclaim of active vnodes */
  193 int     prtactive;
  194 
  195 /*
  196  * The workitem queue.
  197  *
  198  * It is useful to delay writes of file data and filesystem metadata
  199  * for tens of seconds so that quickly created and deleted files need
  200  * not waste disk bandwidth being created and removed. To realize this,
  201  * we append vnodes to a "workitem" queue. When running with a soft
  202  * updates implementation, most pending metadata dependencies should
  203  * not wait for more than a few seconds. Thus, mounted on block devices
  204  * are delayed only about a half the time that file data is delayed.
  205  * Similarly, directory updates are more critical, so are only delayed
  206  * about a third the time that file data is delayed. Thus, there are
  207  * SYNCER_MAXDELAY queues that are processed round-robin at a rate of
  208  * one each second (driven off the filesystem syncer process). The
  209  * syncer_delayno variable indicates the next queue that is to be processed.
  210  * Items that need to be processed soon are placed in this queue:
  211  *
  212  *      syncer_workitem_pending[syncer_delayno]
  213  *
  214  * A delay of fifteen seconds is done by placing the request fifteen
  215  * entries later in the queue:
  216  *
  217  *      syncer_workitem_pending[(syncer_delayno + 15) & syncer_mask]
  218  *
  219  */
  220 static int syncer_delayno;
  221 static long syncer_mask;
  222 LIST_HEAD(synclist, bufobj);
  223 static struct synclist *syncer_workitem_pending;
  224 /*
  225  * The sync_mtx protects:
  226  *      bo->bo_synclist
  227  *      sync_vnode_count
  228  *      syncer_delayno
  229  *      syncer_state
  230  *      syncer_workitem_pending
  231  *      syncer_worklist_len
  232  *      rushjob
  233  */
  234 static struct mtx sync_mtx;
  235 
  236 #define SYNCER_MAXDELAY         32
  237 static int syncer_maxdelay = SYNCER_MAXDELAY;   /* maximum delay time */
  238 static int syncdelay = 30;              /* max time to delay syncing data */
  239 static int filedelay = 30;              /* time to delay syncing files */
  240 SYSCTL_INT(_kern, OID_AUTO, filedelay, CTLFLAG_RW, &filedelay, 0, "");
  241 static int dirdelay = 29;               /* time to delay syncing directories */
  242 SYSCTL_INT(_kern, OID_AUTO, dirdelay, CTLFLAG_RW, &dirdelay, 0, "");
  243 static int metadelay = 28;              /* time to delay syncing metadata */
  244 SYSCTL_INT(_kern, OID_AUTO, metadelay, CTLFLAG_RW, &metadelay, 0, "");
  245 static int rushjob;             /* number of slots to run ASAP */
  246 static int stat_rush_requests;  /* number of times I/O speeded up */
  247 SYSCTL_INT(_debug, OID_AUTO, rush_requests, CTLFLAG_RW, &stat_rush_requests, 0, "");
  248 
  249 /*
  250  * When shutting down the syncer, run it at four times normal speed.
  251  */
  252 #define SYNCER_SHUTDOWN_SPEEDUP         4
  253 static int sync_vnode_count;
  254 static int syncer_worklist_len;
  255 static enum { SYNCER_RUNNING, SYNCER_SHUTTING_DOWN, SYNCER_FINAL_DELAY }
  256     syncer_state;
  257 
  258 /*
  259  * Number of vnodes we want to exist at any one time.  This is mostly used
  260  * to size hash tables in vnode-related code.  It is normally not used in
  261  * getnewvnode(), as wantfreevnodes is normally nonzero.)
  262  *
  263  * XXX desiredvnodes is historical cruft and should not exist.
  264  */
  265 int desiredvnodes;
  266 SYSCTL_INT(_kern, KERN_MAXVNODES, maxvnodes, CTLFLAG_RW,
  267     &desiredvnodes, 0, "Maximum number of vnodes");
  268 SYSCTL_INT(_kern, OID_AUTO, minvnodes, CTLFLAG_RW,
  269     &wantfreevnodes, 0, "Minimum number of vnodes (legacy)");
  270 static int vnlru_nowhere;
  271 SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RW,
  272     &vnlru_nowhere, 0, "Number of times the vnlru process ran without success");
  273 
  274 /*
  275  * Macros to control when a vnode is freed and recycled.  All require
  276  * the vnode interlock.
  277  */
  278 #define VCANRECYCLE(vp) (((vp)->v_iflag & VI_FREE) && !(vp)->v_holdcnt)
  279 #define VSHOULDFREE(vp) (!((vp)->v_iflag & VI_FREE) && !(vp)->v_holdcnt)
  280 #define VSHOULDBUSY(vp) (((vp)->v_iflag & VI_FREE) && (vp)->v_holdcnt)
  281 
  282 
  283 /*
  284  * Initialize the vnode management data structures.
  285  */
  286 #ifndef MAXVNODES_MAX
  287 #define MAXVNODES_MAX   100000
  288 #endif
  289 static void
  290 vntblinit(void *dummy __unused)
  291 {
  292 
  293         /*
  294          * Desiredvnodes is a function of the physical memory size and
  295          * the kernel's heap size.  Specifically, desiredvnodes scales
  296          * in proportion to the physical memory size until two fifths
  297          * of the kernel's heap size is consumed by vnodes and vm
  298          * objects.
  299          */
  300         desiredvnodes = min(maxproc + cnt.v_page_count / 4, 2 * vm_kmem_size /
  301             (5 * (sizeof(struct vm_object) + sizeof(struct vnode))));
  302         if (desiredvnodes > MAXVNODES_MAX) {
  303                 if (bootverbose)
  304                         printf("Reducing kern.maxvnodes %d -> %d\n",
  305                             desiredvnodes, MAXVNODES_MAX);
  306                 desiredvnodes = MAXVNODES_MAX;
  307         }
  308         wantfreevnodes = desiredvnodes / 4;
  309         mtx_init(&mntid_mtx, "mntid", NULL, MTX_DEF);
  310         TAILQ_INIT(&vnode_free_list);
  311         mtx_init(&vnode_free_list_mtx, "vnode_free_list", NULL, MTX_DEF);
  312         vnode_zone = uma_zcreate("VNODE", sizeof (struct vnode), NULL, NULL,
  313             NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  314         vnodepoll_zone = uma_zcreate("VNODEPOLL", sizeof (struct vpollinfo),
  315             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  316         /*
  317          * Initialize the filesystem syncer.
  318          */
  319         syncer_workitem_pending = hashinit(syncer_maxdelay, M_VNODE,
  320                 &syncer_mask);
  321         syncer_maxdelay = syncer_mask + 1;
  322         mtx_init(&sync_mtx, "Syncer mtx", NULL, MTX_DEF);
  323 }
  324 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_FIRST, vntblinit, NULL)
  325 
  326 
  327 /*
  328  * Mark a mount point as busy. Used to synchronize access and to delay
  329  * unmounting. Interlock is not released on failure.
  330  */
  331 int
  332 vfs_busy(struct mount *mp, int flags, struct mtx *interlkp,
  333     struct thread *td)
  334 {
  335         int lkflags;
  336 
  337         MNT_ILOCK(mp);
  338         MNT_REF(mp);
  339         if (mp->mnt_kern_flag & MNTK_UNMOUNT) {
  340                 if (flags & LK_NOWAIT) {
  341                         MNT_REL(mp);
  342                         MNT_IUNLOCK(mp);
  343                         return (ENOENT);
  344                 }
  345                 if (interlkp)
  346                         mtx_unlock(interlkp);
  347                 mp->mnt_kern_flag |= MNTK_MWAIT;
  348                 /*
  349                  * Since all busy locks are shared except the exclusive
  350                  * lock granted when unmounting, the only place that a
  351                  * wakeup needs to be done is at the release of the
  352                  * exclusive lock at the end of dounmount.
  353                  */
  354                 msleep(mp, MNT_MTX(mp), PVFS, "vfs_busy", 0);
  355                 MNT_REL(mp);
  356                 MNT_IUNLOCK(mp);
  357                 if (interlkp)
  358                         mtx_lock(interlkp);
  359                 return (ENOENT);
  360         }
  361         if (interlkp)
  362                 mtx_unlock(interlkp);
  363         lkflags = LK_SHARED | LK_INTERLOCK;
  364         if (lockmgr(&mp->mnt_lock, lkflags, MNT_MTX(mp), td))
  365                 panic("vfs_busy: unexpected lock failure");
  366         return (0);
  367 }
  368 
  369 /*
  370  * Free a busy filesystem.
  371  */
  372 void
  373 vfs_unbusy(struct mount *mp, struct thread *td)
  374 {
  375 
  376         lockmgr(&mp->mnt_lock, LK_RELEASE, NULL, td);
  377         vfs_rel(mp);
  378 }
  379 
  380 /*
  381  * Lookup a mount point by filesystem identifier.
  382  */
  383 struct mount *
  384 vfs_getvfs(fsid_t *fsid)
  385 {
  386         struct mount *mp;
  387 
  388         mtx_lock(&mountlist_mtx);
  389         TAILQ_FOREACH(mp, &mountlist, mnt_list) {
  390                 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
  391                     mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
  392                         vfs_ref(mp);
  393                         mtx_unlock(&mountlist_mtx);
  394                         return (mp);
  395                 }
  396         }
  397         mtx_unlock(&mountlist_mtx);
  398         return ((struct mount *) 0);
  399 }
  400 
  401 /*
  402  * Check if a user can access privileged mount options.
  403  */
  404 int
  405 vfs_suser(struct mount *mp, struct thread *td)
  406 {
  407         int error;
  408 
  409         /*
  410          * If the thread is jailed, but this is not a jail-friendly file
  411          * system, deny immediately.
  412          */
  413         if (jailed(td->td_ucred) && !(mp->mnt_vfc->vfc_flags & VFCF_JAIL))
  414                 return (EPERM);
  415 
  416         /*
  417          * If the file system was mounted outside a jail and a jailed thread
  418          * tries to access it, deny immediately.
  419          */
  420         if (!jailed(mp->mnt_cred) && jailed(td->td_ucred))
  421                 return (EPERM);
  422 
  423         /*
  424          * If the file system was mounted inside different jail that the jail of
  425          * the calling thread, deny immediately.
  426          */
  427         if (jailed(mp->mnt_cred) && jailed(td->td_ucred) &&
  428             mp->mnt_cred->cr_prison != td->td_ucred->cr_prison) {
  429                 return (EPERM);
  430         }
  431 
  432         if ((mp->mnt_flag & MNT_USER) == 0 ||
  433             mp->mnt_cred->cr_uid != td->td_ucred->cr_uid) {
  434                 if ((error = priv_check(td, PRIV_VFS_MOUNT_OWNER)) != 0)
  435                         return (error);
  436         }
  437         return (0);
  438 }
  439 
  440 /*
  441  * Get a new unique fsid.  Try to make its val[0] unique, since this value
  442  * will be used to create fake device numbers for stat().  Also try (but
  443  * not so hard) make its val[0] unique mod 2^16, since some emulators only
  444  * support 16-bit device numbers.  We end up with unique val[0]'s for the
  445  * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls.
  446  *
  447  * Keep in mind that several mounts may be running in parallel.  Starting
  448  * the search one past where the previous search terminated is both a
  449  * micro-optimization and a defense against returning the same fsid to
  450  * different mounts.
  451  */
  452 void
  453 vfs_getnewfsid(struct mount *mp)
  454 {
  455         static u_int16_t mntid_base;
  456         struct mount *nmp;
  457         fsid_t tfsid;
  458         int mtype;
  459 
  460         mtx_lock(&mntid_mtx);
  461         mtype = mp->mnt_vfc->vfc_typenum;
  462         tfsid.val[1] = mtype;
  463         mtype = (mtype & 0xFF) << 24;
  464         for (;;) {
  465                 tfsid.val[0] = makedev(255,
  466                     mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF));
  467                 mntid_base++;
  468                 if ((nmp = vfs_getvfs(&tfsid)) == NULL)
  469                         break;
  470                 vfs_rel(nmp);
  471         }
  472         mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
  473         mp->mnt_stat.f_fsid.val[1] = tfsid.val[1];
  474         mtx_unlock(&mntid_mtx);
  475 }
  476 
  477 /*
  478  * Knob to control the precision of file timestamps:
  479  *
  480  *   0 = seconds only; nanoseconds zeroed.
  481  *   1 = seconds and nanoseconds, accurate within 1/HZ.
  482  *   2 = seconds and nanoseconds, truncated to microseconds.
  483  * >=3 = seconds and nanoseconds, maximum precision.
  484  */
  485 enum { TSP_SEC, TSP_HZ, TSP_USEC, TSP_NSEC };
  486 
  487 static int timestamp_precision = TSP_SEC;
  488 SYSCTL_INT(_vfs, OID_AUTO, timestamp_precision, CTLFLAG_RW,
  489     &timestamp_precision, 0, "");
  490 
  491 /*
  492  * Get a current timestamp.
  493  */
  494 void
  495 vfs_timestamp(struct timespec *tsp)
  496 {
  497         struct timeval tv;
  498 
  499         switch (timestamp_precision) {
  500         case TSP_SEC:
  501                 tsp->tv_sec = time_second;
  502                 tsp->tv_nsec = 0;
  503                 break;
  504         case TSP_HZ:
  505                 getnanotime(tsp);
  506                 break;
  507         case TSP_USEC:
  508                 microtime(&tv);
  509                 TIMEVAL_TO_TIMESPEC(&tv, tsp);
  510                 break;
  511         case TSP_NSEC:
  512         default:
  513                 nanotime(tsp);
  514                 break;
  515         }
  516 }
  517 
  518 /*
  519  * Set vnode attributes to VNOVAL
  520  */
  521 void
  522 vattr_null(struct vattr *vap)
  523 {
  524 
  525         vap->va_type = VNON;
  526         vap->va_size = VNOVAL;
  527         vap->va_bytes = VNOVAL;
  528         vap->va_mode = VNOVAL;
  529         vap->va_nlink = VNOVAL;
  530         vap->va_uid = VNOVAL;
  531         vap->va_gid = VNOVAL;
  532         vap->va_fsid = VNOVAL;
  533         vap->va_fileid = VNOVAL;
  534         vap->va_blocksize = VNOVAL;
  535         vap->va_rdev = VNOVAL;
  536         vap->va_atime.tv_sec = VNOVAL;
  537         vap->va_atime.tv_nsec = VNOVAL;
  538         vap->va_mtime.tv_sec = VNOVAL;
  539         vap->va_mtime.tv_nsec = VNOVAL;
  540         vap->va_ctime.tv_sec = VNOVAL;
  541         vap->va_ctime.tv_nsec = VNOVAL;
  542         vap->va_birthtime.tv_sec = VNOVAL;
  543         vap->va_birthtime.tv_nsec = VNOVAL;
  544         vap->va_flags = VNOVAL;
  545         vap->va_gen = VNOVAL;
  546         vap->va_vaflags = 0;
  547 }
  548 
  549 /*
  550  * This routine is called when we have too many vnodes.  It attempts
  551  * to free <count> vnodes and will potentially free vnodes that still
  552  * have VM backing store (VM backing store is typically the cause
  553  * of a vnode blowout so we want to do this).  Therefore, this operation
  554  * is not considered cheap.
  555  *
  556  * A number of conditions may prevent a vnode from being reclaimed.
  557  * the buffer cache may have references on the vnode, a directory
  558  * vnode may still have references due to the namei cache representing
  559  * underlying files, or the vnode may be in active use.   It is not
  560  * desireable to reuse such vnodes.  These conditions may cause the
  561  * number of vnodes to reach some minimum value regardless of what
  562  * you set kern.maxvnodes to.  Do not set kern.maxvnodes too low.
  563  */
  564 static int
  565 vlrureclaim(struct mount *mp)
  566 {
  567         struct thread *td;
  568         struct vnode *vp;
  569         int done;
  570         int trigger;
  571         int usevnodes;
  572         int count;
  573 
  574         /*
  575          * Calculate the trigger point, don't allow user
  576          * screwups to blow us up.   This prevents us from
  577          * recycling vnodes with lots of resident pages.  We
  578          * aren't trying to free memory, we are trying to
  579          * free vnodes.
  580          */
  581         usevnodes = desiredvnodes;
  582         if (usevnodes <= 0)
  583                 usevnodes = 1;
  584         trigger = cnt.v_page_count * 2 / usevnodes;
  585         done = 0;
  586         td = curthread;
  587         vn_start_write(NULL, &mp, V_WAIT);
  588         MNT_ILOCK(mp);
  589         count = mp->mnt_nvnodelistsize / 10 + 1;
  590         while (count != 0) {
  591                 vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
  592                 while (vp != NULL && vp->v_type == VMARKER)
  593                         vp = TAILQ_NEXT(vp, v_nmntvnodes);
  594                 if (vp == NULL)
  595                         break;
  596                 TAILQ_REMOVE(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
  597                 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
  598                 --count;
  599                 if (!VI_TRYLOCK(vp))
  600                         goto next_iter;
  601                 /*
  602                  * If it's been deconstructed already, it's still
  603                  * referenced, or it exceeds the trigger, skip it.
  604                  */
  605                 if (vp->v_usecount || !LIST_EMPTY(&(vp)->v_cache_src) ||
  606                     (vp->v_iflag & VI_DOOMED) != 0 || (vp->v_object != NULL &&
  607                     vp->v_object->resident_page_count > trigger)) {
  608                         VI_UNLOCK(vp);
  609                         goto next_iter;
  610                 }
  611                 MNT_IUNLOCK(mp);
  612                 vholdl(vp);
  613                 if (VOP_LOCK(vp, LK_INTERLOCK|LK_EXCLUSIVE|LK_NOWAIT, td)) {
  614                         vdrop(vp);
  615                         goto next_iter_mntunlocked;
  616                 }
  617                 VI_LOCK(vp);
  618                 /*
  619                  * v_usecount may have been bumped after VOP_LOCK() dropped
  620                  * the vnode interlock and before it was locked again.
  621                  *
  622                  * It is not necessary to recheck VI_DOOMED because it can
  623                  * only be set by another thread that holds both the vnode
  624                  * lock and vnode interlock.  If another thread has the
  625                  * vnode lock before we get to VOP_LOCK() and obtains the
  626                  * vnode interlock after VOP_LOCK() drops the vnode
  627                  * interlock, the other thread will be unable to drop the
  628                  * vnode lock before our VOP_LOCK() call fails.
  629                  */
  630                 if (vp->v_usecount || !LIST_EMPTY(&(vp)->v_cache_src) ||
  631                     (vp->v_object != NULL &&
  632                     vp->v_object->resident_page_count > trigger)) {
  633                         VOP_UNLOCK(vp, LK_INTERLOCK, td);
  634                         goto next_iter_mntunlocked;
  635                 }
  636                 KASSERT((vp->v_iflag & VI_DOOMED) == 0,
  637                     ("VI_DOOMED unexpectedly detected in vlrureclaim()"));
  638                 vgonel(vp);
  639                 VOP_UNLOCK(vp, 0, td);
  640                 vdropl(vp);
  641                 done++;
  642 next_iter_mntunlocked:
  643                 if ((count % 256) != 0)
  644                         goto relock_mnt;
  645                 goto yield;
  646 next_iter:
  647                 if ((count % 256) != 0)
  648                         continue;
  649                 MNT_IUNLOCK(mp);
  650 yield:
  651                 uio_yield();
  652 relock_mnt:
  653                 MNT_ILOCK(mp);
  654         }
  655         MNT_IUNLOCK(mp);
  656         vn_finished_write(mp);
  657         return done;
  658 }
  659 
  660 /*
  661  * Attempt to keep the free list at wantfreevnodes length.
  662  */
  663 static void
  664 vnlru_free(int count)
  665 {
  666         struct vnode *vp;
  667         int vfslocked;
  668 
  669         mtx_assert(&vnode_free_list_mtx, MA_OWNED);
  670         for (; count > 0; count--) {
  671                 vp = TAILQ_FIRST(&vnode_free_list);
  672                 /*
  673                  * The list can be modified while the free_list_mtx
  674                  * has been dropped and vp could be NULL here.
  675                  */
  676                 if (!vp)
  677                         break;
  678                 VNASSERT(vp->v_op != NULL, vp,
  679                     ("vnlru_free: vnode already reclaimed."));
  680                 TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
  681                 /*
  682                  * Don't recycle if we can't get the interlock.
  683                  */
  684                 if (!VI_TRYLOCK(vp)) {
  685                         TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
  686                         continue;
  687                 }
  688                 VNASSERT(VCANRECYCLE(vp), vp,
  689                     ("vp inconsistent on freelist"));
  690                 freevnodes--;
  691                 vp->v_iflag &= ~VI_FREE;
  692                 vholdl(vp);
  693                 mtx_unlock(&vnode_free_list_mtx);
  694                 VI_UNLOCK(vp);
  695                 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  696                 vtryrecycle(vp);
  697                 VFS_UNLOCK_GIANT(vfslocked);
  698                 /*
  699                  * If the recycled succeeded this vdrop will actually free
  700                  * the vnode.  If not it will simply place it back on
  701                  * the free list.
  702                  */
  703                 vdrop(vp);
  704                 mtx_lock(&vnode_free_list_mtx);
  705         }
  706 }
  707 /*
  708  * Attempt to recycle vnodes in a context that is always safe to block.
  709  * Calling vlrurecycle() from the bowels of filesystem code has some
  710  * interesting deadlock problems.
  711  */
  712 static struct proc *vnlruproc;
  713 static int vnlruproc_sig;
  714 
  715 static void
  716 vnlru_proc(void)
  717 {
  718         struct mount *mp, *nmp;
  719         int done;
  720         struct proc *p = vnlruproc;
  721         struct thread *td = curthread;
  722 
  723         EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, p,
  724             SHUTDOWN_PRI_FIRST);
  725 
  726         mtx_lock(&Giant);
  727 
  728         for (;;) {
  729                 kthread_suspend_check(p);
  730                 mtx_lock(&vnode_free_list_mtx);
  731                 if (freevnodes > wantfreevnodes)
  732                         vnlru_free(freevnodes - wantfreevnodes);
  733                 if (numvnodes <= desiredvnodes * 9 / 10) {
  734                         vnlruproc_sig = 0;
  735                         wakeup(&vnlruproc_sig);
  736                         msleep(vnlruproc, &vnode_free_list_mtx,
  737                             PVFS|PDROP, "vlruwt", hz);
  738                         continue;
  739                 }
  740                 mtx_unlock(&vnode_free_list_mtx);
  741                 done = 0;
  742                 mtx_lock(&mountlist_mtx);
  743                 for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
  744                         int vfsunlocked;
  745                         if (vfs_busy(mp, LK_NOWAIT, &mountlist_mtx, td)) {
  746                                 nmp = TAILQ_NEXT(mp, mnt_list);
  747                                 continue;
  748                         }
  749                         if (!VFS_NEEDSGIANT(mp)) {
  750                                 mtx_unlock(&Giant);
  751                                 vfsunlocked = 1;
  752                         } else
  753                                 vfsunlocked = 0;
  754                         done += vlrureclaim(mp);
  755                         if (vfsunlocked)
  756                                 mtx_lock(&Giant);
  757                         mtx_lock(&mountlist_mtx);
  758                         nmp = TAILQ_NEXT(mp, mnt_list);
  759                         vfs_unbusy(mp, td);
  760                 }
  761                 mtx_unlock(&mountlist_mtx);
  762                 if (done == 0) {
  763                         EVENTHANDLER_INVOKE(vfs_lowvnodes, desiredvnodes / 10);
  764 #if 0
  765                         /* These messages are temporary debugging aids */
  766                         if (vnlru_nowhere < 5)
  767                                 printf("vnlru process getting nowhere..\n");
  768                         else if (vnlru_nowhere == 5)
  769                                 printf("vnlru process messages stopped.\n");
  770 #endif
  771                         vnlru_nowhere++;
  772                         tsleep(vnlruproc, PPAUSE, "vlrup", hz * 3);
  773                 } else
  774                         uio_yield();
  775         }
  776 }
  777 
  778 static struct kproc_desc vnlru_kp = {
  779         "vnlru",
  780         vnlru_proc,
  781         &vnlruproc
  782 };
  783 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp)
  784 
  785 /*
  786  * Routines having to do with the management of the vnode table.
  787  */
  788 
  789 static void
  790 vdestroy(struct vnode *vp)
  791 {
  792         struct bufobj *bo;
  793 
  794         CTR1(KTR_VFS, "vdestroy vp %p", vp);
  795         mtx_lock(&vnode_free_list_mtx);
  796         numvnodes--;
  797         mtx_unlock(&vnode_free_list_mtx);
  798         bo = &vp->v_bufobj;
  799         VNASSERT((vp->v_iflag & VI_FREE) == 0, vp,
  800             ("cleaned vnode still on the free list."));
  801         VNASSERT(vp->v_data == NULL, vp, ("cleaned vnode isn't"));
  802         VNASSERT(vp->v_holdcnt == 0, vp, ("Non-zero hold count"));
  803         VNASSERT(vp->v_usecount == 0, vp, ("Non-zero use count"));
  804         VNASSERT(vp->v_writecount == 0, vp, ("Non-zero write count"));
  805         VNASSERT(bo->bo_numoutput == 0, vp, ("Clean vnode has pending I/O's"));
  806         VNASSERT(bo->bo_clean.bv_cnt == 0, vp, ("cleanbufcnt not 0"));
  807         VNASSERT(bo->bo_clean.bv_root == NULL, vp, ("cleanblkroot not NULL"));
  808         VNASSERT(bo->bo_dirty.bv_cnt == 0, vp, ("dirtybufcnt not 0"));
  809         VNASSERT(bo->bo_dirty.bv_root == NULL, vp, ("dirtyblkroot not NULL"));
  810         VNASSERT(TAILQ_EMPTY(&vp->v_cache_dst), vp, ("vp has namecache dst"));
  811         VNASSERT(LIST_EMPTY(&vp->v_cache_src), vp, ("vp has namecache src"));
  812         VI_UNLOCK(vp);
  813 #ifdef MAC
  814         mac_destroy_vnode(vp);
  815 #endif
  816         if (vp->v_pollinfo != NULL) {
  817                 knlist_destroy(&vp->v_pollinfo->vpi_selinfo.si_note);
  818                 mtx_destroy(&vp->v_pollinfo->vpi_lock);
  819                 uma_zfree(vnodepoll_zone, vp->v_pollinfo);
  820         }
  821 #ifdef INVARIANTS
  822         /* XXX Elsewhere we can detect an already freed vnode via NULL v_op. */
  823         vp->v_op = NULL;
  824 #endif
  825         lockdestroy(vp->v_vnlock);
  826         mtx_destroy(&vp->v_interlock);
  827         uma_zfree(vnode_zone, vp);
  828 }
  829 
  830 /*
  831  * Try to recycle a freed vnode.  We abort if anyone picks up a reference
  832  * before we actually vgone().  This function must be called with the vnode
  833  * held to prevent the vnode from being returned to the free list midway
  834  * through vgone().
  835  */
  836 static int
  837 vtryrecycle(struct vnode *vp)
  838 {
  839         struct thread *td = curthread;
  840         struct mount *vnmp;
  841 
  842         CTR1(KTR_VFS, "vtryrecycle: trying vp %p", vp);
  843         VNASSERT(vp->v_holdcnt, vp,
  844             ("vtryrecycle: Recycling vp %p without a reference.", vp));
  845         /*
  846          * This vnode may found and locked via some other list, if so we
  847          * can't recycle it yet.
  848          */
  849         if (VOP_LOCK(vp, LK_EXCLUSIVE | LK_NOWAIT, td) != 0)
  850                 return (EWOULDBLOCK);
  851         /*
  852          * Don't recycle if its filesystem is being suspended.
  853          */
  854         if (vn_start_write(vp, &vnmp, V_NOWAIT) != 0) {
  855                 VOP_UNLOCK(vp, 0, td);
  856                 return (EBUSY);
  857         }
  858         /*
  859          * If we got this far, we need to acquire the interlock and see if
  860          * anyone picked up this vnode from another list.  If not, we will
  861          * mark it with DOOMED via vgonel() so that anyone who does find it
  862          * will skip over it.
  863          */
  864         VI_LOCK(vp);
  865         if (vp->v_usecount) {
  866                 VOP_UNLOCK(vp, LK_INTERLOCK, td);
  867                 vn_finished_write(vnmp);
  868                 return (EBUSY);
  869         }
  870         if ((vp->v_iflag & VI_DOOMED) == 0)
  871                 vgonel(vp);
  872         VOP_UNLOCK(vp, LK_INTERLOCK, td);
  873         vn_finished_write(vnmp);
  874         CTR1(KTR_VFS, "vtryrecycle: recycled vp %p", vp);
  875         return (0);
  876 }
  877 
  878 /*
  879  * Return the next vnode from the free list.
  880  */
  881 int
  882 getnewvnode(const char *tag, struct mount *mp, struct vop_vector *vops,
  883     struct vnode **vpp)
  884 {
  885         struct vnode *vp = NULL;
  886         struct bufobj *bo;
  887 
  888         mtx_lock(&vnode_free_list_mtx);
  889         /*
  890          * Lend our context to reclaim vnodes if they've exceeded the max.
  891          */
  892         if (freevnodes > wantfreevnodes)
  893                 vnlru_free(1);
  894         /*
  895          * Wait for available vnodes.
  896          */
  897         if (numvnodes > desiredvnodes) {
  898                 if (mp != NULL && (mp->mnt_kern_flag & MNTK_SUSPEND)) {
  899                         /*
  900                          * File system is beeing suspended, we cannot risk a
  901                          * deadlock here, so allocate new vnode anyway.
  902                          */
  903                         if (freevnodes > wantfreevnodes)
  904                                 vnlru_free(freevnodes - wantfreevnodes);
  905                         goto alloc;
  906                 }
  907                 if (vnlruproc_sig == 0) {
  908                         vnlruproc_sig = 1;      /* avoid unnecessary wakeups */
  909                         wakeup(vnlruproc);
  910                 }
  911                 msleep(&vnlruproc_sig, &vnode_free_list_mtx, PVFS,
  912                     "vlruwk", hz);
  913 #if 0   /* XXX Not all VFS_VGET/ffs_vget callers check returns. */
  914                 if (numvnodes > desiredvnodes) {
  915                         mtx_unlock(&vnode_free_list_mtx);
  916                         return (ENFILE);
  917                 }
  918 #endif
  919         }
  920 alloc:
  921         numvnodes++;
  922         mtx_unlock(&vnode_free_list_mtx);
  923         vp = (struct vnode *) uma_zalloc(vnode_zone, M_WAITOK|M_ZERO);
  924         /*
  925          * Setup locks.
  926          */
  927         vp->v_vnlock = &vp->v_lock;
  928         mtx_init(&vp->v_interlock, "vnode interlock", NULL, MTX_DEF);
  929         /*
  930          * By default, don't allow shared locks unless filesystems
  931          * opt-in.
  932          */
  933         lockinit(vp->v_vnlock, PVFS, tag, VLKTIMEOUT, LK_NOSHARE);
  934         /*
  935          * Initialize bufobj.
  936          */
  937         bo = &vp->v_bufobj;
  938         bo->__bo_vnode = vp;
  939         bo->bo_mtx = &vp->v_interlock;
  940         bo->bo_ops = &buf_ops_bio;
  941         bo->bo_private = vp;
  942         TAILQ_INIT(&bo->bo_clean.bv_hd);
  943         TAILQ_INIT(&bo->bo_dirty.bv_hd);
  944         /*
  945          * Initialize namecache.
  946          */
  947         LIST_INIT(&vp->v_cache_src);
  948         TAILQ_INIT(&vp->v_cache_dst);
  949         /*
  950          * Finalize various vnode identity bits.
  951          */
  952         vp->v_type = VNON;
  953         vp->v_tag = tag;
  954         vp->v_op = vops;
  955         v_incr_usecount(vp);
  956         vp->v_data = 0;
  957 #ifdef MAC
  958         mac_init_vnode(vp);
  959         if (mp != NULL && (mp->mnt_flag & MNT_MULTILABEL) == 0)
  960                 mac_associate_vnode_singlelabel(mp, vp);
  961         else if (mp == NULL)
  962                 printf("NULL mp in getnewvnode()\n");
  963 #endif
  964         if (mp != NULL) {
  965                 bo->bo_bsize = mp->mnt_stat.f_iosize;
  966                 if ((mp->mnt_kern_flag & MNTK_NOKNOTE) != 0)
  967                         vp->v_vflag |= VV_NOKNOTE;
  968         }
  969 
  970         CTR2(KTR_VFS, "getnewvnode: mp %p vp %p", mp, vp);
  971         *vpp = vp;
  972         return (0);
  973 }
  974 
  975 /*
  976  * Delete from old mount point vnode list, if on one.
  977  */
  978 static void
  979 delmntque(struct vnode *vp)
  980 {
  981         struct mount *mp;
  982 
  983         mp = vp->v_mount;
  984         if (mp == NULL)
  985                 return;
  986         MNT_ILOCK(mp);
  987         vp->v_mount = NULL;
  988         VNASSERT(mp->mnt_nvnodelistsize > 0, vp,
  989                 ("bad mount point vnode list size"));
  990         TAILQ_REMOVE(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
  991         mp->mnt_nvnodelistsize--;
  992         MNT_REL(mp);
  993         MNT_IUNLOCK(mp);
  994 }
  995 
  996 static void
  997 insmntque_stddtr(struct vnode *vp, void *dtr_arg)
  998 {
  999         struct thread *td;
 1000 
 1001         td = curthread; /* XXX ? */
 1002         vp->v_data = NULL;
 1003         vp->v_op = &dead_vnodeops;
 1004         /* XXX non mp-safe fs may still call insmntque with vnode
 1005            unlocked */
 1006         if (!VOP_ISLOCKED(vp, td))
 1007                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1008         vgone(vp);
 1009         vput(vp);
 1010 }
 1011 
 1012 /*
 1013  * Insert into list of vnodes for the new mount point, if available.
 1014  */
 1015 int
 1016 insmntque1(struct vnode *vp, struct mount *mp,
 1017         void (*dtr)(struct vnode *, void *), void *dtr_arg)
 1018 {
 1019 
 1020         KASSERT(vp->v_mount == NULL,
 1021                 ("insmntque: vnode already on per mount vnode list"));
 1022         VNASSERT(mp != NULL, vp, ("Don't call insmntque(foo, NULL)"));
 1023         MNT_ILOCK(mp);
 1024         if ((mp->mnt_kern_flag & MNTK_NOINSMNTQ) != 0 &&
 1025             mp->mnt_nvnodelistsize == 0) {
 1026                 MNT_IUNLOCK(mp);
 1027                 if (dtr != NULL)
 1028                         dtr(vp, dtr_arg);
 1029                 return (EBUSY);
 1030         }
 1031         vp->v_mount = mp;
 1032         MNT_REF(mp);
 1033         TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
 1034         VNASSERT(mp->mnt_nvnodelistsize >= 0, vp,
 1035                 ("neg mount point vnode list size"));
 1036         mp->mnt_nvnodelistsize++;
 1037         MNT_IUNLOCK(mp);
 1038         return (0);
 1039 }
 1040 
 1041 int
 1042 insmntque(struct vnode *vp, struct mount *mp)
 1043 {
 1044 
 1045         return (insmntque1(vp, mp, insmntque_stddtr, NULL));
 1046 }
 1047 
 1048 /*
 1049  * Flush out and invalidate all buffers associated with a bufobj
 1050  * Called with the underlying object locked.
 1051  */
 1052 int
 1053 bufobj_invalbuf(struct bufobj *bo, int flags, struct thread *td, int slpflag,
 1054     int slptimeo)
 1055 {
 1056         int error;
 1057 
 1058         BO_LOCK(bo);
 1059         if (flags & V_SAVE) {
 1060                 error = bufobj_wwait(bo, slpflag, slptimeo);
 1061                 if (error) {
 1062                         BO_UNLOCK(bo);
 1063                         return (error);
 1064                 }
 1065                 if (bo->bo_dirty.bv_cnt > 0) {
 1066                         BO_UNLOCK(bo);
 1067                         if ((error = BO_SYNC(bo, MNT_WAIT, td)) != 0)
 1068                                 return (error);
 1069                         /*
 1070                          * XXX We could save a lock/unlock if this was only
 1071                          * enabled under INVARIANTS
 1072                          */
 1073                         BO_LOCK(bo);
 1074                         if (bo->bo_numoutput > 0 || bo->bo_dirty.bv_cnt > 0)
 1075                                 panic("vinvalbuf: dirty bufs");
 1076                 }
 1077         }
 1078         /*
 1079          * If you alter this loop please notice that interlock is dropped and
 1080          * reacquired in flushbuflist.  Special care is needed to ensure that
 1081          * no race conditions occur from this.
 1082          */
 1083         do {
 1084                 error = flushbuflist(&bo->bo_clean,
 1085                     flags, bo, slpflag, slptimeo);
 1086                 if (error == 0)
 1087                         error = flushbuflist(&bo->bo_dirty,
 1088                             flags, bo, slpflag, slptimeo);
 1089                 if (error != 0 && error != EAGAIN) {
 1090                         BO_UNLOCK(bo);
 1091                         return (error);
 1092                 }
 1093         } while (error != 0);
 1094 
 1095         /*
 1096          * Wait for I/O to complete.  XXX needs cleaning up.  The vnode can
 1097          * have write I/O in-progress but if there is a VM object then the
 1098          * VM object can also have read-I/O in-progress.
 1099          */
 1100         do {
 1101                 bufobj_wwait(bo, 0, 0);
 1102                 BO_UNLOCK(bo);
 1103                 if (bo->bo_object != NULL) {
 1104                         VM_OBJECT_LOCK(bo->bo_object);
 1105                         vm_object_pip_wait(bo->bo_object, "bovlbx");
 1106                         VM_OBJECT_UNLOCK(bo->bo_object);
 1107                 }
 1108                 BO_LOCK(bo);
 1109         } while (bo->bo_numoutput > 0);
 1110         BO_UNLOCK(bo);
 1111 
 1112         /*
 1113          * Destroy the copy in the VM cache, too.
 1114          */
 1115         if (bo->bo_object != NULL) {
 1116                 VM_OBJECT_LOCK(bo->bo_object);
 1117                 vm_object_page_remove(bo->bo_object, 0, 0,
 1118                         (flags & V_SAVE) ? TRUE : FALSE);
 1119                 VM_OBJECT_UNLOCK(bo->bo_object);
 1120         }
 1121 
 1122 #ifdef INVARIANTS
 1123         BO_LOCK(bo);
 1124         if ((flags & (V_ALT | V_NORMAL)) == 0 &&
 1125             (bo->bo_dirty.bv_cnt > 0 || bo->bo_clean.bv_cnt > 0))
 1126                 panic("vinvalbuf: flush failed");
 1127         BO_UNLOCK(bo);
 1128 #endif
 1129         return (0);
 1130 }
 1131 
 1132 /*
 1133  * Flush out and invalidate all buffers associated with a vnode.
 1134  * Called with the underlying object locked.
 1135  */
 1136 int
 1137 vinvalbuf(struct vnode *vp, int flags, struct thread *td, int slpflag,
 1138     int slptimeo)
 1139 {
 1140 
 1141         CTR2(KTR_VFS, "vinvalbuf vp %p flags %d", vp, flags);
 1142         ASSERT_VOP_LOCKED(vp, "vinvalbuf");
 1143         return (bufobj_invalbuf(&vp->v_bufobj, flags, td, slpflag, slptimeo));
 1144 }
 1145 
 1146 /*
 1147  * Flush out buffers on the specified list.
 1148  *
 1149  */
 1150 static int
 1151 flushbuflist( struct bufv *bufv, int flags, struct bufobj *bo, int slpflag,
 1152     int slptimeo)
 1153 {
 1154         struct buf *bp, *nbp;
 1155         int retval, error;
 1156         daddr_t lblkno;
 1157         b_xflags_t xflags;
 1158 
 1159         ASSERT_BO_LOCKED(bo);
 1160 
 1161         retval = 0;
 1162         TAILQ_FOREACH_SAFE(bp, &bufv->bv_hd, b_bobufs, nbp) {
 1163                 if (((flags & V_NORMAL) && (bp->b_xflags & BX_ALTDATA)) ||
 1164                     ((flags & V_ALT) && (bp->b_xflags & BX_ALTDATA) == 0)) {
 1165                         continue;
 1166                 }
 1167                 lblkno = 0;
 1168                 xflags = 0;
 1169                 if (nbp != NULL) {
 1170                         lblkno = nbp->b_lblkno;
 1171                         xflags = nbp->b_xflags &
 1172                                 (BX_BKGRDMARKER | BX_VNDIRTY | BX_VNCLEAN);
 1173                 }
 1174                 retval = EAGAIN;
 1175                 error = BUF_TIMELOCK(bp,
 1176                     LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK, BO_MTX(bo),
 1177                     "flushbuf", slpflag, slptimeo);
 1178                 if (error) {
 1179                         BO_LOCK(bo);
 1180                         return (error != ENOLCK ? error : EAGAIN);
 1181                 }
 1182                 KASSERT(bp->b_bufobj == bo,
 1183                     ("bp %p wrong b_bufobj %p should be %p",
 1184                     bp, bp->b_bufobj, bo));
 1185                 if (bp->b_bufobj != bo) {       /* XXX: necessary ? */
 1186                         BUF_UNLOCK(bp);
 1187                         BO_LOCK(bo);
 1188                         return (EAGAIN);
 1189                 }
 1190                 /*
 1191                  * XXX Since there are no node locks for NFS, I
 1192                  * believe there is a slight chance that a delayed
 1193                  * write will occur while sleeping just above, so
 1194                  * check for it.
 1195                  */
 1196                 if (((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) &&
 1197                     (flags & V_SAVE)) {
 1198                         bremfree(bp);
 1199                         bp->b_flags |= B_ASYNC;
 1200                         bwrite(bp);
 1201                         BO_LOCK(bo);
 1202                         return (EAGAIN);        /* XXX: why not loop ? */
 1203                 }
 1204                 bremfree(bp);
 1205                 bp->b_flags |= (B_INVAL | B_RELBUF);
 1206                 bp->b_flags &= ~B_ASYNC;
 1207                 brelse(bp);
 1208                 BO_LOCK(bo);
 1209                 if (nbp != NULL &&
 1210                     (nbp->b_bufobj != bo ||
 1211                      nbp->b_lblkno != lblkno ||
 1212                      (nbp->b_xflags &
 1213                       (BX_BKGRDMARKER | BX_VNDIRTY | BX_VNCLEAN)) != xflags))
 1214                         break;                  /* nbp invalid */
 1215         }
 1216         return (retval);
 1217 }
 1218 
 1219 /*
 1220  * Truncate a file's buffer and pages to a specified length.  This
 1221  * is in lieu of the old vinvalbuf mechanism, which performed unneeded
 1222  * sync activity.
 1223  */
 1224 int
 1225 vtruncbuf(struct vnode *vp, struct ucred *cred, struct thread *td,
 1226     off_t length, int blksize)
 1227 {
 1228         struct buf *bp, *nbp;
 1229         int anyfreed;
 1230         int trunclbn;
 1231         struct bufobj *bo;
 1232 
 1233         CTR2(KTR_VFS, "vtruncbuf vp %p length %jd", vp, length);
 1234         /*
 1235          * Round up to the *next* lbn.
 1236          */
 1237         trunclbn = (length + blksize - 1) / blksize;
 1238 
 1239         ASSERT_VOP_LOCKED(vp, "vtruncbuf");
 1240 restart:
 1241         VI_LOCK(vp);
 1242         bo = &vp->v_bufobj;
 1243         anyfreed = 1;
 1244         for (;anyfreed;) {
 1245                 anyfreed = 0;
 1246                 TAILQ_FOREACH_SAFE(bp, &bo->bo_clean.bv_hd, b_bobufs, nbp) {
 1247                         if (bp->b_lblkno < trunclbn)
 1248                                 continue;
 1249                         if (BUF_LOCK(bp,
 1250                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1251                             VI_MTX(vp)) == ENOLCK)
 1252                                 goto restart;
 1253 
 1254                         bremfree(bp);
 1255                         bp->b_flags |= (B_INVAL | B_RELBUF);
 1256                         bp->b_flags &= ~B_ASYNC;
 1257                         brelse(bp);
 1258                         anyfreed = 1;
 1259 
 1260                         if (nbp != NULL &&
 1261                             (((nbp->b_xflags & BX_VNCLEAN) == 0) ||
 1262                             (nbp->b_vp != vp) ||
 1263                             (nbp->b_flags & B_DELWRI))) {
 1264                                 goto restart;
 1265                         }
 1266                         VI_LOCK(vp);
 1267                 }
 1268 
 1269                 TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
 1270                         if (bp->b_lblkno < trunclbn)
 1271                                 continue;
 1272                         if (BUF_LOCK(bp,
 1273                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1274                             VI_MTX(vp)) == ENOLCK)
 1275                                 goto restart;
 1276                         bremfree(bp);
 1277                         bp->b_flags |= (B_INVAL | B_RELBUF);
 1278                         bp->b_flags &= ~B_ASYNC;
 1279                         brelse(bp);
 1280                         anyfreed = 1;
 1281                         if (nbp != NULL &&
 1282                             (((nbp->b_xflags & BX_VNDIRTY) == 0) ||
 1283                             (nbp->b_vp != vp) ||
 1284                             (nbp->b_flags & B_DELWRI) == 0)) {
 1285                                 goto restart;
 1286                         }
 1287                         VI_LOCK(vp);
 1288                 }
 1289         }
 1290 
 1291         if (length > 0) {
 1292 restartsync:
 1293                 TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
 1294                         if (bp->b_lblkno > 0)
 1295                                 continue;
 1296                         /*
 1297                          * Since we hold the vnode lock this should only
 1298                          * fail if we're racing with the buf daemon.
 1299                          */
 1300                         if (BUF_LOCK(bp,
 1301                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1302                             VI_MTX(vp)) == ENOLCK) {
 1303                                 goto restart;
 1304                         }
 1305                         VNASSERT((bp->b_flags & B_DELWRI), vp,
 1306                             ("buf(%p) on dirty queue without DELWRI", bp));
 1307 
 1308                         bremfree(bp);
 1309                         bawrite(bp);
 1310                         VI_LOCK(vp);
 1311                         goto restartsync;
 1312                 }
 1313         }
 1314 
 1315         bufobj_wwait(bo, 0, 0);
 1316         VI_UNLOCK(vp);
 1317         vnode_pager_setsize(vp, length);
 1318 
 1319         return (0);
 1320 }
 1321 
 1322 /*
 1323  * buf_splay() - splay tree core for the clean/dirty list of buffers in
 1324  *               a vnode.
 1325  *
 1326  *      NOTE: We have to deal with the special case of a background bitmap
 1327  *      buffer, a situation where two buffers will have the same logical
 1328  *      block offset.  We want (1) only the foreground buffer to be accessed
 1329  *      in a lookup and (2) must differentiate between the foreground and
 1330  *      background buffer in the splay tree algorithm because the splay
 1331  *      tree cannot normally handle multiple entities with the same 'index'.
 1332  *      We accomplish this by adding differentiating flags to the splay tree's
 1333  *      numerical domain.
 1334  */
 1335 static
 1336 struct buf *
 1337 buf_splay(daddr_t lblkno, b_xflags_t xflags, struct buf *root)
 1338 {
 1339         struct buf dummy;
 1340         struct buf *lefttreemax, *righttreemin, *y;
 1341 
 1342         if (root == NULL)
 1343                 return (NULL);
 1344         lefttreemax = righttreemin = &dummy;
 1345         for (;;) {
 1346                 if (lblkno < root->b_lblkno ||
 1347                     (lblkno == root->b_lblkno &&
 1348                     (xflags & BX_BKGRDMARKER) < (root->b_xflags & BX_BKGRDMARKER))) {
 1349                         if ((y = root->b_left) == NULL)
 1350                                 break;
 1351                         if (lblkno < y->b_lblkno) {
 1352                                 /* Rotate right. */
 1353                                 root->b_left = y->b_right;
 1354                                 y->b_right = root;
 1355                                 root = y;
 1356                                 if ((y = root->b_left) == NULL)
 1357                                         break;
 1358                         }
 1359                         /* Link into the new root's right tree. */
 1360                         righttreemin->b_left = root;
 1361                         righttreemin = root;
 1362                 } else if (lblkno > root->b_lblkno ||
 1363                     (lblkno == root->b_lblkno &&
 1364                     (xflags & BX_BKGRDMARKER) > (root->b_xflags & BX_BKGRDMARKER))) {
 1365                         if ((y = root->b_right) == NULL)
 1366                                 break;
 1367                         if (lblkno > y->b_lblkno) {
 1368                                 /* Rotate left. */
 1369                                 root->b_right = y->b_left;
 1370                                 y->b_left = root;
 1371                                 root = y;
 1372                                 if ((y = root->b_right) == NULL)
 1373                                         break;
 1374                         }
 1375                         /* Link into the new root's left tree. */
 1376                         lefttreemax->b_right = root;
 1377                         lefttreemax = root;
 1378                 } else {
 1379                         break;
 1380                 }
 1381                 root = y;
 1382         }
 1383         /* Assemble the new root. */
 1384         lefttreemax->b_right = root->b_left;
 1385         righttreemin->b_left = root->b_right;
 1386         root->b_left = dummy.b_right;
 1387         root->b_right = dummy.b_left;
 1388         return (root);
 1389 }
 1390 
 1391 static void
 1392 buf_vlist_remove(struct buf *bp)
 1393 {
 1394         struct buf *root;
 1395         struct bufv *bv;
 1396 
 1397         KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
 1398         ASSERT_BO_LOCKED(bp->b_bufobj);
 1399         KASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) !=
 1400             (BX_VNDIRTY|BX_VNCLEAN),
 1401             ("buf_vlist_remove: Buf %p is on two lists", bp));
 1402         if (bp->b_xflags & BX_VNDIRTY)
 1403                 bv = &bp->b_bufobj->bo_dirty;
 1404         else
 1405                 bv = &bp->b_bufobj->bo_clean;
 1406         if (bp != bv->bv_root) {
 1407                 root = buf_splay(bp->b_lblkno, bp->b_xflags, bv->bv_root);
 1408                 KASSERT(root == bp, ("splay lookup failed in remove"));
 1409         }
 1410         if (bp->b_left == NULL) {
 1411                 root = bp->b_right;
 1412         } else {
 1413                 root = buf_splay(bp->b_lblkno, bp->b_xflags, bp->b_left);
 1414                 root->b_right = bp->b_right;
 1415         }
 1416         bv->bv_root = root;
 1417         TAILQ_REMOVE(&bv->bv_hd, bp, b_bobufs);
 1418         bv->bv_cnt--;
 1419         bp->b_xflags &= ~(BX_VNDIRTY | BX_VNCLEAN);
 1420 }
 1421 
 1422 /*
 1423  * Add the buffer to the sorted clean or dirty block list using a
 1424  * splay tree algorithm.
 1425  *
 1426  * NOTE: xflags is passed as a constant, optimizing this inline function!
 1427  */
 1428 static void
 1429 buf_vlist_add(struct buf *bp, struct bufobj *bo, b_xflags_t xflags)
 1430 {
 1431         struct buf *root;
 1432         struct bufv *bv;
 1433 
 1434         ASSERT_BO_LOCKED(bo);
 1435         KASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) == 0,
 1436             ("buf_vlist_add: Buf %p has existing xflags %d", bp, bp->b_xflags));
 1437         bp->b_xflags |= xflags;
 1438         if (xflags & BX_VNDIRTY)
 1439                 bv = &bo->bo_dirty;
 1440         else
 1441                 bv = &bo->bo_clean;
 1442 
 1443         root = buf_splay(bp->b_lblkno, bp->b_xflags, bv->bv_root);
 1444         if (root == NULL) {
 1445                 bp->b_left = NULL;
 1446                 bp->b_right = NULL;
 1447                 TAILQ_INSERT_TAIL(&bv->bv_hd, bp, b_bobufs);
 1448         } else if (bp->b_lblkno < root->b_lblkno ||
 1449             (bp->b_lblkno == root->b_lblkno &&
 1450             (bp->b_xflags & BX_BKGRDMARKER) < (root->b_xflags & BX_BKGRDMARKER))) {
 1451                 bp->b_left = root->b_left;
 1452                 bp->b_right = root;
 1453                 root->b_left = NULL;
 1454                 TAILQ_INSERT_BEFORE(root, bp, b_bobufs);
 1455         } else {
 1456                 bp->b_right = root->b_right;
 1457                 bp->b_left = root;
 1458                 root->b_right = NULL;
 1459                 TAILQ_INSERT_AFTER(&bv->bv_hd, root, bp, b_bobufs);
 1460         }
 1461         bv->bv_cnt++;
 1462         bv->bv_root = bp;
 1463 }
 1464 
 1465 /*
 1466  * Lookup a buffer using the splay tree.  Note that we specifically avoid
 1467  * shadow buffers used in background bitmap writes.
 1468  *
 1469  * This code isn't quite efficient as it could be because we are maintaining
 1470  * two sorted lists and do not know which list the block resides in.
 1471  *
 1472  * During a "make buildworld" the desired buffer is found at one of
 1473  * the roots more than 60% of the time.  Thus, checking both roots
 1474  * before performing either splay eliminates unnecessary splays on the
 1475  * first tree splayed.
 1476  */
 1477 struct buf *
 1478 gbincore(struct bufobj *bo, daddr_t lblkno)
 1479 {
 1480         struct buf *bp;
 1481 
 1482         ASSERT_BO_LOCKED(bo);
 1483         if ((bp = bo->bo_clean.bv_root) != NULL &&
 1484             bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1485                 return (bp);
 1486         if ((bp = bo->bo_dirty.bv_root) != NULL &&
 1487             bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1488                 return (bp);
 1489         if ((bp = bo->bo_clean.bv_root) != NULL) {
 1490                 bo->bo_clean.bv_root = bp = buf_splay(lblkno, 0, bp);
 1491                 if (bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1492                         return (bp);
 1493         }
 1494         if ((bp = bo->bo_dirty.bv_root) != NULL) {
 1495                 bo->bo_dirty.bv_root = bp = buf_splay(lblkno, 0, bp);
 1496                 if (bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1497                         return (bp);
 1498         }
 1499         return (NULL);
 1500 }
 1501 
 1502 /*
 1503  * Associate a buffer with a vnode.
 1504  */
 1505 void
 1506 bgetvp(struct vnode *vp, struct buf *bp)
 1507 {
 1508 
 1509         VNASSERT(bp->b_vp == NULL, bp->b_vp, ("bgetvp: not free"));
 1510 
 1511         CTR3(KTR_BUF, "bgetvp(%p) vp %p flags %X", bp, vp, bp->b_flags);
 1512         VNASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) == 0, vp,
 1513             ("bgetvp: bp already attached! %p", bp));
 1514 
 1515         ASSERT_VI_LOCKED(vp, "bgetvp");
 1516         vholdl(vp);
 1517         if (VFS_NEEDSGIANT(vp->v_mount) ||
 1518             vp->v_bufobj.bo_flag & BO_NEEDSGIANT)
 1519                 bp->b_flags |= B_NEEDSGIANT;
 1520         bp->b_vp = vp;
 1521         bp->b_bufobj = &vp->v_bufobj;
 1522         /*
 1523          * Insert onto list for new vnode.
 1524          */
 1525         buf_vlist_add(bp, &vp->v_bufobj, BX_VNCLEAN);
 1526 }
 1527 
 1528 /*
 1529  * Disassociate a buffer from a vnode.
 1530  */
 1531 void
 1532 brelvp(struct buf *bp)
 1533 {
 1534         struct bufobj *bo;
 1535         struct vnode *vp;
 1536 
 1537         CTR3(KTR_BUF, "brelvp(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
 1538         KASSERT(bp->b_vp != NULL, ("brelvp: NULL"));
 1539 
 1540         /*
 1541          * Delete from old vnode list, if on one.
 1542          */
 1543         vp = bp->b_vp;          /* XXX */
 1544         bo = bp->b_bufobj;
 1545         BO_LOCK(bo);
 1546         if (bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN))
 1547                 buf_vlist_remove(bp);
 1548         else
 1549                 panic("brelvp: Buffer %p not on queue.", bp);
 1550         if ((bo->bo_flag & BO_ONWORKLST) && bo->bo_dirty.bv_cnt == 0) {
 1551                 bo->bo_flag &= ~BO_ONWORKLST;
 1552                 mtx_lock(&sync_mtx);
 1553                 LIST_REMOVE(bo, bo_synclist);
 1554                 syncer_worklist_len--;
 1555                 mtx_unlock(&sync_mtx);
 1556         }
 1557         bp->b_flags &= ~B_NEEDSGIANT;
 1558         bp->b_vp = NULL;
 1559         bp->b_bufobj = NULL;
 1560         vdropl(vp);
 1561 }
 1562 
 1563 /*
 1564  * Add an item to the syncer work queue.
 1565  */
 1566 static void
 1567 vn_syncer_add_to_worklist(struct bufobj *bo, int delay)
 1568 {
 1569         int slot;
 1570 
 1571         ASSERT_BO_LOCKED(bo);
 1572 
 1573         mtx_lock(&sync_mtx);
 1574         if (bo->bo_flag & BO_ONWORKLST)
 1575                 LIST_REMOVE(bo, bo_synclist);
 1576         else {
 1577                 bo->bo_flag |= BO_ONWORKLST;
 1578                 syncer_worklist_len++;
 1579         }
 1580 
 1581         if (delay > syncer_maxdelay - 2)
 1582                 delay = syncer_maxdelay - 2;
 1583         slot = (syncer_delayno + delay) & syncer_mask;
 1584 
 1585         LIST_INSERT_HEAD(&syncer_workitem_pending[slot], bo, bo_synclist);
 1586         mtx_unlock(&sync_mtx);
 1587 }
 1588 
 1589 static int
 1590 sysctl_vfs_worklist_len(SYSCTL_HANDLER_ARGS)
 1591 {
 1592         int error, len;
 1593 
 1594         mtx_lock(&sync_mtx);
 1595         len = syncer_worklist_len - sync_vnode_count;
 1596         mtx_unlock(&sync_mtx);
 1597         error = SYSCTL_OUT(req, &len, sizeof(len));
 1598         return (error);
 1599 }
 1600 
 1601 SYSCTL_PROC(_vfs, OID_AUTO, worklist_len, CTLTYPE_INT | CTLFLAG_RD, NULL, 0,
 1602     sysctl_vfs_worklist_len, "I", "Syncer thread worklist length");
 1603 
 1604 static struct proc *updateproc;
 1605 static void sched_sync(void);
 1606 static struct kproc_desc up_kp = {
 1607         "syncer",
 1608         sched_sync,
 1609         &updateproc
 1610 };
 1611 SYSINIT(syncer, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &up_kp)
 1612 
 1613 static int
 1614 sync_vnode(struct synclist *slp, struct bufobj **bo, struct thread *td)
 1615 {
 1616         struct vnode *vp;
 1617         struct mount *mp;
 1618         int vfslocked;
 1619 
 1620         vfslocked = 0;
 1621 restart:
 1622         *bo = LIST_FIRST(slp);
 1623         if (*bo == NULL) {
 1624                 VFS_UNLOCK_GIANT(vfslocked);
 1625                 return (0);
 1626         }
 1627         vp = (*bo)->__bo_vnode; /* XXX */
 1628         if (VFS_NEEDSGIANT(vp->v_mount)) {
 1629                 if (!vfslocked) {
 1630                         vfslocked = 1;
 1631                         if (mtx_trylock(&Giant) == 0) {
 1632                                 mtx_unlock(&sync_mtx);
 1633                                 mtx_lock(&Giant);
 1634                                 mtx_lock(&sync_mtx);
 1635                                 goto restart;
 1636                         }
 1637                 }
 1638         } else {
 1639                 VFS_UNLOCK_GIANT(vfslocked);
 1640                 vfslocked = 0;
 1641         }
 1642         if (VOP_ISLOCKED(vp, NULL) != 0) {
 1643                 VFS_UNLOCK_GIANT(vfslocked);
 1644                 return (1);
 1645         }
 1646         if (VI_TRYLOCK(vp) == 0) {
 1647                 VFS_UNLOCK_GIANT(vfslocked);
 1648                 return (1);
 1649         }
 1650         /*
 1651          * We use vhold in case the vnode does not
 1652          * successfully sync.  vhold prevents the vnode from
 1653          * going away when we unlock the sync_mtx so that
 1654          * we can acquire the vnode interlock.
 1655          */
 1656         vholdl(vp);
 1657         mtx_unlock(&sync_mtx);
 1658         VI_UNLOCK(vp);
 1659         if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
 1660                 vdrop(vp);
 1661                 VFS_UNLOCK_GIANT(vfslocked);
 1662                 mtx_lock(&sync_mtx);
 1663                 return (1);
 1664         }
 1665         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1666         (void) VOP_FSYNC(vp, MNT_LAZY, td);
 1667         VOP_UNLOCK(vp, 0, td);
 1668         vn_finished_write(mp);
 1669         VI_LOCK(vp);
 1670         if (((*bo)->bo_flag & BO_ONWORKLST) != 0) {
 1671                 /*
 1672                  * Put us back on the worklist.  The worklist
 1673                  * routine will remove us from our current
 1674                  * position and then add us back in at a later
 1675                  * position.
 1676                  */
 1677                 vn_syncer_add_to_worklist(*bo, syncdelay);
 1678         }
 1679         vdropl(vp);
 1680         VFS_UNLOCK_GIANT(vfslocked);
 1681         mtx_lock(&sync_mtx);
 1682         return (0);
 1683 }
 1684 
 1685 /*
 1686  * System filesystem synchronizer daemon.
 1687  */
 1688 static void
 1689 sched_sync(void)
 1690 {
 1691         struct synclist *next;
 1692         struct synclist *slp;
 1693         struct bufobj *bo;
 1694         long starttime;
 1695         struct thread *td = curthread;
 1696         static int dummychan;
 1697         int last_work_seen;
 1698         int net_worklist_len;
 1699         int syncer_final_iter;
 1700         int first_printf;
 1701         int error;
 1702 
 1703         last_work_seen = 0;
 1704         syncer_final_iter = 0;
 1705         first_printf = 1;
 1706         syncer_state = SYNCER_RUNNING;
 1707         starttime = time_uptime;
 1708         td->td_pflags |= TDP_NORUNNINGBUF;
 1709 
 1710         EVENTHANDLER_REGISTER(shutdown_pre_sync, syncer_shutdown, td->td_proc,
 1711             SHUTDOWN_PRI_LAST);
 1712 
 1713         mtx_lock(&sync_mtx);
 1714         for (;;) {
 1715                 if (syncer_state == SYNCER_FINAL_DELAY &&
 1716                     syncer_final_iter == 0) {
 1717                         mtx_unlock(&sync_mtx);
 1718                         kthread_suspend_check(td->td_proc);
 1719                         mtx_lock(&sync_mtx);
 1720                 }
 1721                 net_worklist_len = syncer_worklist_len - sync_vnode_count;
 1722                 if (syncer_state != SYNCER_RUNNING &&
 1723                     starttime != time_uptime) {
 1724                         if (first_printf) {
 1725                                 printf("\nSyncing disks, vnodes remaining...");
 1726                                 first_printf = 0;
 1727                         }
 1728                         printf("%d ", net_worklist_len);
 1729                 }
 1730                 starttime = time_uptime;
 1731 
 1732                 /*
 1733                  * Push files whose dirty time has expired.  Be careful
 1734                  * of interrupt race on slp queue.
 1735                  *
 1736                  * Skip over empty worklist slots when shutting down.
 1737                  */
 1738                 do {
 1739                         slp = &syncer_workitem_pending[syncer_delayno];
 1740                         syncer_delayno += 1;
 1741                         if (syncer_delayno == syncer_maxdelay)
 1742                                 syncer_delayno = 0;
 1743                         next = &syncer_workitem_pending[syncer_delayno];
 1744                         /*
 1745                          * If the worklist has wrapped since the
 1746                          * it was emptied of all but syncer vnodes,
 1747                          * switch to the FINAL_DELAY state and run
 1748                          * for one more second.
 1749                          */
 1750                         if (syncer_state == SYNCER_SHUTTING_DOWN &&
 1751                             net_worklist_len == 0 &&
 1752                             last_work_seen == syncer_delayno) {
 1753                                 syncer_state = SYNCER_FINAL_DELAY;
 1754                                 syncer_final_iter = SYNCER_SHUTDOWN_SPEEDUP;
 1755                         }
 1756                 } while (syncer_state != SYNCER_RUNNING && LIST_EMPTY(slp) &&
 1757                     syncer_worklist_len > 0);
 1758 
 1759                 /*
 1760                  * Keep track of the last time there was anything
 1761                  * on the worklist other than syncer vnodes.
 1762                  * Return to the SHUTTING_DOWN state if any
 1763                  * new work appears.
 1764                  */
 1765                 if (net_worklist_len > 0 || syncer_state == SYNCER_RUNNING)
 1766                         last_work_seen = syncer_delayno;
 1767                 if (net_worklist_len > 0 && syncer_state == SYNCER_FINAL_DELAY)
 1768                         syncer_state = SYNCER_SHUTTING_DOWN;
 1769                 while (!LIST_EMPTY(slp)) {
 1770                         error = sync_vnode(slp, &bo, td);
 1771                         if (error == 1) {
 1772                                 LIST_REMOVE(bo, bo_synclist);
 1773                                 LIST_INSERT_HEAD(next, bo, bo_synclist);
 1774                                 continue;
 1775                         }
 1776                 }
 1777                 if (syncer_state == SYNCER_FINAL_DELAY && syncer_final_iter > 0)
 1778                         syncer_final_iter--;
 1779                 /*
 1780                  * The variable rushjob allows the kernel to speed up the
 1781                  * processing of the filesystem syncer process. A rushjob
 1782                  * value of N tells the filesystem syncer to process the next
 1783                  * N seconds worth of work on its queue ASAP. Currently rushjob
 1784                  * is used by the soft update code to speed up the filesystem
 1785                  * syncer process when the incore state is getting so far
 1786                  * ahead of the disk that the kernel memory pool is being
 1787                  * threatened with exhaustion.
 1788                  */
 1789                 if (rushjob > 0) {
 1790                         rushjob -= 1;
 1791                         continue;
 1792                 }
 1793                 /*
 1794                  * Just sleep for a short period of time between
 1795                  * iterations when shutting down to allow some I/O
 1796                  * to happen.
 1797                  *
 1798                  * If it has taken us less than a second to process the
 1799                  * current work, then wait. Otherwise start right over
 1800                  * again. We can still lose time if any single round
 1801                  * takes more than two seconds, but it does not really
 1802                  * matter as we are just trying to generally pace the
 1803                  * filesystem activity.
 1804                  */
 1805                 if (syncer_state != SYNCER_RUNNING)
 1806                         msleep(&dummychan, &sync_mtx, PPAUSE, "syncfnl",
 1807                             hz / SYNCER_SHUTDOWN_SPEEDUP);
 1808                 else if (time_uptime == starttime)
 1809                         msleep(&lbolt, &sync_mtx, PPAUSE, "syncer", 0);
 1810         }
 1811 }
 1812 
 1813 /*
 1814  * Request the syncer daemon to speed up its work.
 1815  * We never push it to speed up more than half of its
 1816  * normal turn time, otherwise it could take over the cpu.
 1817  */
 1818 int
 1819 speedup_syncer(void)
 1820 {
 1821         struct thread *td;
 1822         int ret = 0;
 1823 
 1824         td = FIRST_THREAD_IN_PROC(updateproc);
 1825         mtx_lock(&sync_mtx);
 1826         if (rushjob < syncdelay / 2) {
 1827                 rushjob += 1;
 1828                 stat_rush_requests += 1;
 1829                 ret = 1;
 1830         }
 1831         mtx_unlock(&sync_mtx);
 1832         sleepq_remove(td, &lbolt);
 1833         return (ret);
 1834 }
 1835 
 1836 /*
 1837  * Tell the syncer to speed up its work and run though its work
 1838  * list several times, then tell it to shut down.
 1839  */
 1840 static void
 1841 syncer_shutdown(void *arg, int howto)
 1842 {
 1843         struct thread *td;
 1844 
 1845         if (howto & RB_NOSYNC)
 1846                 return;
 1847         td = FIRST_THREAD_IN_PROC(updateproc);
 1848         mtx_lock(&sync_mtx);
 1849         syncer_state = SYNCER_SHUTTING_DOWN;
 1850         rushjob = 0;
 1851         mtx_unlock(&sync_mtx);
 1852         sleepq_remove(td, &lbolt);
 1853         kproc_shutdown(arg, howto);
 1854 }
 1855 
 1856 /*
 1857  * Reassign a buffer from one vnode to another.
 1858  * Used to assign file specific control information
 1859  * (indirect blocks) to the vnode to which they belong.
 1860  */
 1861 void
 1862 reassignbuf(struct buf *bp)
 1863 {
 1864         struct vnode *vp;
 1865         struct bufobj *bo;
 1866         int delay;
 1867 #ifdef INVARIANTS
 1868         struct bufv *bv;
 1869 #endif
 1870 
 1871         vp = bp->b_vp;
 1872         bo = bp->b_bufobj;
 1873         ++reassignbufcalls;
 1874 
 1875         CTR3(KTR_BUF, "reassignbuf(%p) vp %p flags %X",
 1876             bp, bp->b_vp, bp->b_flags);
 1877         /*
 1878          * B_PAGING flagged buffers cannot be reassigned because their vp
 1879          * is not fully linked in.
 1880          */
 1881         if (bp->b_flags & B_PAGING)
 1882                 panic("cannot reassign paging buffer");
 1883 
 1884         /*
 1885          * Delete from old vnode list, if on one.
 1886          */
 1887         VI_LOCK(vp);
 1888         if (bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN))
 1889                 buf_vlist_remove(bp);
 1890         else
 1891                 panic("reassignbuf: Buffer %p not on queue.", bp);
 1892         /*
 1893          * If dirty, put on list of dirty buffers; otherwise insert onto list
 1894          * of clean buffers.
 1895          */
 1896         if (bp->b_flags & B_DELWRI) {
 1897                 if ((bo->bo_flag & BO_ONWORKLST) == 0) {
 1898                         switch (vp->v_type) {
 1899                         case VDIR:
 1900                                 delay = dirdelay;
 1901                                 break;
 1902                         case VCHR:
 1903                                 delay = metadelay;
 1904                                 break;
 1905                         default:
 1906                                 delay = filedelay;
 1907                         }
 1908                         vn_syncer_add_to_worklist(bo, delay);
 1909                 }
 1910                 buf_vlist_add(bp, bo, BX_VNDIRTY);
 1911         } else {
 1912                 buf_vlist_add(bp, bo, BX_VNCLEAN);
 1913 
 1914                 if ((bo->bo_flag & BO_ONWORKLST) && bo->bo_dirty.bv_cnt == 0) {
 1915                         mtx_lock(&sync_mtx);
 1916                         LIST_REMOVE(bo, bo_synclist);
 1917                         syncer_worklist_len--;
 1918                         mtx_unlock(&sync_mtx);
 1919                         bo->bo_flag &= ~BO_ONWORKLST;
 1920                 }
 1921         }
 1922 #ifdef INVARIANTS
 1923         bv = &bo->bo_clean;
 1924         bp = TAILQ_FIRST(&bv->bv_hd);
 1925         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1926             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1927         bp = TAILQ_LAST(&bv->bv_hd, buflists);
 1928         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1929             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1930         bv = &bo->bo_dirty;
 1931         bp = TAILQ_FIRST(&bv->bv_hd);
 1932         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1933             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1934         bp = TAILQ_LAST(&bv->bv_hd, buflists);
 1935         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1936             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1937 #endif
 1938         VI_UNLOCK(vp);
 1939 }
 1940 
 1941 /*
 1942  * Increment the use and hold counts on the vnode, taking care to reference
 1943  * the driver's usecount if this is a chardev.  The vholdl() will remove
 1944  * the vnode from the free list if it is presently free.  Requires the
 1945  * vnode interlock and returns with it held.
 1946  */
 1947 static void
 1948 v_incr_usecount(struct vnode *vp)
 1949 {
 1950 
 1951         CTR3(KTR_VFS, "v_incr_usecount: vp %p holdcnt %d usecount %d\n",
 1952             vp, vp->v_holdcnt, vp->v_usecount);
 1953         vp->v_usecount++;
 1954         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 1955                 dev_lock();
 1956                 vp->v_rdev->si_usecount++;
 1957                 dev_unlock();
 1958         }
 1959         vholdl(vp);
 1960 }
 1961 
 1962 /*
 1963  * Turn a holdcnt into a use+holdcnt such that only one call to
 1964  * v_decr_usecount is needed.
 1965  */
 1966 static void
 1967 v_upgrade_usecount(struct vnode *vp)
 1968 {
 1969 
 1970         CTR3(KTR_VFS, "v_upgrade_usecount: vp %p holdcnt %d usecount %d\n",
 1971             vp, vp->v_holdcnt, vp->v_usecount);
 1972         vp->v_usecount++;
 1973         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 1974                 dev_lock();
 1975                 vp->v_rdev->si_usecount++;
 1976                 dev_unlock();
 1977         }
 1978 }
 1979 
 1980 /*
 1981  * Decrement the vnode use and hold count along with the driver's usecount
 1982  * if this is a chardev.  The vdropl() below releases the vnode interlock
 1983  * as it may free the vnode.
 1984  */
 1985 static void
 1986 v_decr_usecount(struct vnode *vp)
 1987 {
 1988 
 1989         CTR3(KTR_VFS, "v_decr_usecount: vp %p holdcnt %d usecount %d\n",
 1990             vp, vp->v_holdcnt, vp->v_usecount);
 1991         ASSERT_VI_LOCKED(vp, __FUNCTION__);
 1992         VNASSERT(vp->v_usecount > 0, vp,
 1993             ("v_decr_usecount: negative usecount"));
 1994         vp->v_usecount--;
 1995         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 1996                 dev_lock();
 1997                 vp->v_rdev->si_usecount--;
 1998                 dev_unlock();
 1999         }
 2000         vdropl(vp);
 2001 }
 2002 
 2003 /*
 2004  * Decrement only the use count and driver use count.  This is intended to
 2005  * be paired with a follow on vdropl() to release the remaining hold count.
 2006  * In this way we may vgone() a vnode with a 0 usecount without risk of
 2007  * having it end up on a free list because the hold count is kept above 0.
 2008  */
 2009 static void
 2010 v_decr_useonly(struct vnode *vp)
 2011 {
 2012 
 2013         CTR3(KTR_VFS, "v_decr_useonly: vp %p holdcnt %d usecount %d\n",
 2014             vp, vp->v_holdcnt, vp->v_usecount);
 2015         ASSERT_VI_LOCKED(vp, __FUNCTION__);
 2016         VNASSERT(vp->v_usecount > 0, vp,
 2017             ("v_decr_useonly: negative usecount"));
 2018         vp->v_usecount--;
 2019         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 2020                 dev_lock();
 2021                 vp->v_rdev->si_usecount--;
 2022                 dev_unlock();
 2023         }
 2024 }
 2025 
 2026 /*
 2027  * Grab a particular vnode from the free list, increment its
 2028  * reference count and lock it. The vnode lock bit is set if the
 2029  * vnode is being eliminated in vgone. The process is awakened
 2030  * when the transition is completed, and an error returned to
 2031  * indicate that the vnode is no longer usable (possibly having
 2032  * been changed to a new filesystem type).
 2033  */
 2034 int
 2035 vget(struct vnode *vp, int flags, struct thread *td)
 2036 {
 2037         int oweinact;
 2038         int oldflags;
 2039         int error;
 2040 
 2041         error = 0;
 2042         oldflags = flags;
 2043         oweinact = 0;
 2044         VFS_ASSERT_GIANT(vp->v_mount);
 2045         if ((flags & LK_INTERLOCK) == 0)
 2046                 VI_LOCK(vp);
 2047         /*
 2048          * If the inactive call was deferred because vput() was called
 2049          * with a shared lock, we have to do it here before another thread
 2050          * gets a reference to data that should be dead.
 2051          */
 2052         if (vp->v_iflag & VI_OWEINACT) {
 2053                 if (flags & LK_NOWAIT) {
 2054                         VI_UNLOCK(vp);
 2055                         return (EBUSY);
 2056                 }
 2057                 flags &= ~LK_TYPE_MASK;
 2058                 flags |= LK_EXCLUSIVE;
 2059                 oweinact = 1;
 2060         }
 2061         vholdl(vp);
 2062         if ((error = vn_lock(vp, flags | LK_INTERLOCK, td)) != 0) {
 2063                 vdrop(vp);
 2064                 return (error);
 2065         }
 2066         VI_LOCK(vp);
 2067         /* Upgrade our holdcnt to a usecount. */
 2068         v_upgrade_usecount(vp);
 2069         if (vp->v_iflag & VI_DOOMED && (flags & LK_RETRY) == 0)
 2070                 panic("vget: vn_lock failed to return ENOENT\n");
 2071         if (oweinact) {
 2072                 if (vp->v_iflag & VI_OWEINACT)
 2073                         vinactive(vp, td);
 2074                 VI_UNLOCK(vp);
 2075                 if ((oldflags & LK_TYPE_MASK) == 0)
 2076                         VOP_UNLOCK(vp, 0, td);
 2077         } else
 2078                 VI_UNLOCK(vp);
 2079         return (0);
 2080 }
 2081 
 2082 /*
 2083  * Increase the reference count of a vnode.
 2084  */
 2085 void
 2086 vref(struct vnode *vp)
 2087 {
 2088 
 2089         VI_LOCK(vp);
 2090         v_incr_usecount(vp);
 2091         VI_UNLOCK(vp);
 2092 }
 2093 
 2094 /*
 2095  * Return reference count of a vnode.
 2096  *
 2097  * The results of this call are only guaranteed when some mechanism other
 2098  * than the VI lock is used to stop other processes from gaining references
 2099  * to the vnode.  This may be the case if the caller holds the only reference.
 2100  * This is also useful when stale data is acceptable as race conditions may
 2101  * be accounted for by some other means.
 2102  */
 2103 int
 2104 vrefcnt(struct vnode *vp)
 2105 {
 2106         int usecnt;
 2107 
 2108         VI_LOCK(vp);
 2109         usecnt = vp->v_usecount;
 2110         VI_UNLOCK(vp);
 2111 
 2112         return (usecnt);
 2113 }
 2114 
 2115 
 2116 /*
 2117  * Vnode put/release.
 2118  * If count drops to zero, call inactive routine and return to freelist.
 2119  */
 2120 void
 2121 vrele(struct vnode *vp)
 2122 {
 2123         struct thread *td = curthread;  /* XXX */
 2124 
 2125         KASSERT(vp != NULL, ("vrele: null vp"));
 2126         VFS_ASSERT_GIANT(vp->v_mount);
 2127 
 2128         VI_LOCK(vp);
 2129 
 2130         /* Skip this v_writecount check if we're going to panic below. */
 2131         VNASSERT(vp->v_writecount < vp->v_usecount || vp->v_usecount < 1, vp,
 2132             ("vrele: missed vn_close"));
 2133 
 2134         if (vp->v_usecount > 1 || ((vp->v_iflag & VI_DOINGINACT) &&
 2135             vp->v_usecount == 1)) {
 2136                 v_decr_usecount(vp);
 2137                 return;
 2138         }
 2139         if (vp->v_usecount != 1) {
 2140 #ifdef DIAGNOSTIC
 2141                 vprint("vrele: negative ref count", vp);
 2142 #endif
 2143                 VI_UNLOCK(vp);
 2144                 panic("vrele: negative ref cnt");
 2145         }
 2146         /*
 2147          * We want to hold the vnode until the inactive finishes to
 2148          * prevent vgone() races.  We drop the use count here and the
 2149          * hold count below when we're done.
 2150          */
 2151         v_decr_useonly(vp);
 2152         /*
 2153          * We must call VOP_INACTIVE with the node locked. Mark
 2154          * as VI_DOINGINACT to avoid recursion.
 2155          */
 2156         vp->v_iflag |= VI_OWEINACT;
 2157         if (vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK, td) == 0) {
 2158                 VI_LOCK(vp);
 2159                 if (vp->v_usecount > 0)
 2160                         vp->v_iflag &= ~VI_OWEINACT;
 2161                 if (vp->v_iflag & VI_OWEINACT)
 2162                         vinactive(vp, td);
 2163                 VOP_UNLOCK(vp, 0, td);
 2164         } else {
 2165                 VI_LOCK(vp);
 2166                 if (vp->v_usecount > 0)
 2167                         vp->v_iflag &= ~VI_OWEINACT;
 2168         }
 2169         vdropl(vp);
 2170 }
 2171 
 2172 /*
 2173  * Release an already locked vnode.  This give the same effects as
 2174  * unlock+vrele(), but takes less time and avoids releasing and
 2175  * re-aquiring the lock (as vrele() acquires the lock internally.)
 2176  */
 2177 void
 2178 vput(struct vnode *vp)
 2179 {
 2180         struct thread *td = curthread;  /* XXX */
 2181         int error;
 2182 
 2183         KASSERT(vp != NULL, ("vput: null vp"));
 2184         ASSERT_VOP_LOCKED(vp, "vput");
 2185         VFS_ASSERT_GIANT(vp->v_mount);
 2186         VI_LOCK(vp);
 2187         /* Skip this v_writecount check if we're going to panic below. */
 2188         VNASSERT(vp->v_writecount < vp->v_usecount || vp->v_usecount < 1, vp,
 2189             ("vput: missed vn_close"));
 2190         error = 0;
 2191 
 2192         if (vp->v_usecount > 1 || ((vp->v_iflag & VI_DOINGINACT) &&
 2193             vp->v_usecount == 1)) {
 2194                 VOP_UNLOCK(vp, 0, td);
 2195                 v_decr_usecount(vp);
 2196                 return;
 2197         }
 2198 
 2199         if (vp->v_usecount != 1) {
 2200 #ifdef DIAGNOSTIC
 2201                 vprint("vput: negative ref count", vp);
 2202 #endif
 2203                 panic("vput: negative ref cnt");
 2204         }
 2205         /*
 2206          * We want to hold the vnode until the inactive finishes to
 2207          * prevent vgone() races.  We drop the use count here and the
 2208          * hold count below when we're done.
 2209          */
 2210         v_decr_useonly(vp);
 2211         vp->v_iflag |= VI_OWEINACT;
 2212         if (VOP_ISLOCKED(vp, NULL) != LK_EXCLUSIVE) {
 2213                 error = VOP_LOCK(vp, LK_EXCLUPGRADE|LK_INTERLOCK|LK_NOWAIT, td);
 2214                 VI_LOCK(vp);
 2215                 if (error) {
 2216                         if (vp->v_usecount > 0)
 2217                                 vp->v_iflag &= ~VI_OWEINACT;
 2218                         goto done;
 2219                 }
 2220         }
 2221         if (vp->v_usecount > 0)
 2222                 vp->v_iflag &= ~VI_OWEINACT;
 2223         if (vp->v_iflag & VI_OWEINACT)
 2224                 vinactive(vp, td);
 2225         VOP_UNLOCK(vp, 0, td);
 2226 done:
 2227         vdropl(vp);
 2228 }
 2229 
 2230 /*
 2231  * Somebody doesn't want the vnode recycled.
 2232  */
 2233 void
 2234 vhold(struct vnode *vp)
 2235 {
 2236 
 2237         VI_LOCK(vp);
 2238         vholdl(vp);
 2239         VI_UNLOCK(vp);
 2240 }
 2241 
 2242 void
 2243 vholdl(struct vnode *vp)
 2244 {
 2245 
 2246         vp->v_holdcnt++;
 2247         if (VSHOULDBUSY(vp))
 2248                 vbusy(vp);
 2249 }
 2250 
 2251 /*
 2252  * Note that there is one less who cares about this vnode.  vdrop() is the
 2253  * opposite of vhold().
 2254  */
 2255 void
 2256 vdrop(struct vnode *vp)
 2257 {
 2258 
 2259         VI_LOCK(vp);
 2260         vdropl(vp);
 2261 }
 2262 
 2263 /*
 2264  * Drop the hold count of the vnode.  If this is the last reference to
 2265  * the vnode we will free it if it has been vgone'd otherwise it is
 2266  * placed on the free list.
 2267  */
 2268 void
 2269 vdropl(struct vnode *vp)
 2270 {
 2271 
 2272         ASSERT_VI_LOCKED(vp, "vdropl");
 2273         if (vp->v_holdcnt <= 0)
 2274                 panic("vdrop: holdcnt %d", vp->v_holdcnt);
 2275         vp->v_holdcnt--;
 2276         if (vp->v_holdcnt == 0) {
 2277                 if (vp->v_iflag & VI_DOOMED) {
 2278                         vdestroy(vp);
 2279                         return;
 2280                 } else
 2281                         vfree(vp);
 2282         }
 2283         VI_UNLOCK(vp);
 2284 }
 2285 
 2286 /*
 2287  * Call VOP_INACTIVE on the vnode and manage the DOINGINACT and OWEINACT
 2288  * flags.  DOINGINACT prevents us from recursing in calls to vinactive.
 2289  * OWEINACT tracks whether a vnode missed a call to inactive due to a
 2290  * failed lock upgrade.
 2291  */
 2292 static void
 2293 vinactive(struct vnode *vp, struct thread *td)
 2294 {
 2295 
 2296         ASSERT_VOP_LOCKED(vp, "vinactive");
 2297         ASSERT_VI_LOCKED(vp, "vinactive");
 2298         VNASSERT((vp->v_iflag & VI_DOINGINACT) == 0, vp,
 2299             ("vinactive: recursed on VI_DOINGINACT"));
 2300         vp->v_iflag |= VI_DOINGINACT;
 2301         vp->v_iflag &= ~VI_OWEINACT;
 2302         VI_UNLOCK(vp);
 2303         VOP_INACTIVE(vp, td);
 2304         VI_LOCK(vp);
 2305         VNASSERT(vp->v_iflag & VI_DOINGINACT, vp,
 2306             ("vinactive: lost VI_DOINGINACT"));
 2307         vp->v_iflag &= ~VI_DOINGINACT;
 2308 }
 2309 
 2310 /*
 2311  * Remove any vnodes in the vnode table belonging to mount point mp.
 2312  *
 2313  * If FORCECLOSE is not specified, there should not be any active ones,
 2314  * return error if any are found (nb: this is a user error, not a
 2315  * system error). If FORCECLOSE is specified, detach any active vnodes
 2316  * that are found.
 2317  *
 2318  * If WRITECLOSE is set, only flush out regular file vnodes open for
 2319  * writing.
 2320  *
 2321  * SKIPSYSTEM causes any vnodes marked VV_SYSTEM to be skipped.
 2322  *
 2323  * `rootrefs' specifies the base reference count for the root vnode
 2324  * of this filesystem. The root vnode is considered busy if its
 2325  * v_usecount exceeds this value. On a successful return, vflush(, td)
 2326  * will call vrele() on the root vnode exactly rootrefs times.
 2327  * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must
 2328  * be zero.
 2329  */
 2330 #ifdef DIAGNOSTIC
 2331 static int busyprt = 0;         /* print out busy vnodes */
 2332 SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, "");
 2333 #endif
 2334 
 2335 int
 2336 vflush( struct mount *mp, int rootrefs, int flags, struct thread *td)
 2337 {
 2338         struct vnode *vp, *mvp, *rootvp = NULL;
 2339         struct vattr vattr;
 2340         int busy = 0, error;
 2341 
 2342         CTR1(KTR_VFS, "vflush: mp %p", mp);
 2343         if (rootrefs > 0) {
 2344                 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0,
 2345                     ("vflush: bad args"));
 2346                 /*
 2347                  * Get the filesystem root vnode. We can vput() it
 2348                  * immediately, since with rootrefs > 0, it won't go away.
 2349                  */
 2350                 if ((error = VFS_ROOT(mp, LK_EXCLUSIVE, &rootvp, td)) != 0)
 2351                         return (error);
 2352                 vput(rootvp);
 2353 
 2354         }
 2355         MNT_ILOCK(mp);
 2356 loop:
 2357         MNT_VNODE_FOREACH(vp, mp, mvp) {
 2358 
 2359                 VI_LOCK(vp);
 2360                 vholdl(vp);
 2361                 MNT_IUNLOCK(mp);
 2362                 error = vn_lock(vp, LK_INTERLOCK | LK_EXCLUSIVE, td);
 2363                 if (error) {
 2364                         vdrop(vp);
 2365                         MNT_ILOCK(mp);
 2366                         MNT_VNODE_FOREACH_ABORT_ILOCKED(mp, mvp);
 2367                         goto loop;
 2368                 }
 2369                 /*
 2370                  * Skip over a vnodes marked VV_SYSTEM.
 2371                  */
 2372                 if ((flags & SKIPSYSTEM) && (vp->v_vflag & VV_SYSTEM)) {
 2373                         VOP_UNLOCK(vp, 0, td);
 2374                         vdrop(vp);
 2375                         MNT_ILOCK(mp);
 2376                         continue;
 2377                 }
 2378                 /*
 2379                  * If WRITECLOSE is set, flush out unlinked but still open
 2380                  * files (even if open only for reading) and regular file
 2381                  * vnodes open for writing.
 2382                  */
 2383                 if (flags & WRITECLOSE) {
 2384                         error = VOP_GETATTR(vp, &vattr, td->td_ucred, td);
 2385                         VI_LOCK(vp);
 2386 
 2387                         if ((vp->v_type == VNON ||
 2388                             (error == 0 && vattr.va_nlink > 0)) &&
 2389                             (vp->v_writecount == 0 || vp->v_type != VREG)) {
 2390                                 VOP_UNLOCK(vp, 0, td);
 2391                                 vdropl(vp);
 2392                                 MNT_ILOCK(mp);
 2393                                 continue;
 2394                         }
 2395                 } else
 2396                         VI_LOCK(vp);
 2397                 /*
 2398                  * With v_usecount == 0, all we need to do is clear out the
 2399                  * vnode data structures and we are done.
 2400                  *
 2401                  * If FORCECLOSE is set, forcibly close the vnode.
 2402                  */
 2403                 if (vp->v_usecount == 0 || (flags & FORCECLOSE)) {
 2404                         VNASSERT(vp->v_usecount == 0 ||
 2405                             (vp->v_type != VCHR && vp->v_type != VBLK), vp,
 2406                             ("device VNODE %p is FORCECLOSED", vp));
 2407                         vgonel(vp);
 2408                 } else {
 2409                         busy++;
 2410 #ifdef DIAGNOSTIC
 2411                         if (busyprt)
 2412                                 vprint("vflush: busy vnode", vp);
 2413 #endif
 2414                 }
 2415                 VOP_UNLOCK(vp, 0, td);
 2416                 vdropl(vp);
 2417                 MNT_ILOCK(mp);
 2418         }
 2419         MNT_IUNLOCK(mp);
 2420         if (rootrefs > 0 && (flags & FORCECLOSE) == 0) {
 2421                 /*
 2422                  * If just the root vnode is busy, and if its refcount
 2423                  * is equal to `rootrefs', then go ahead and kill it.
 2424                  */
 2425                 VI_LOCK(rootvp);
 2426                 KASSERT(busy > 0, ("vflush: not busy"));
 2427                 VNASSERT(rootvp->v_usecount >= rootrefs, rootvp,
 2428                     ("vflush: usecount %d < rootrefs %d",
 2429                      rootvp->v_usecount, rootrefs));
 2430                 if (busy == 1 && rootvp->v_usecount == rootrefs) {
 2431                         VOP_LOCK(rootvp, LK_EXCLUSIVE|LK_INTERLOCK, td);
 2432                         vgone(rootvp);
 2433                         VOP_UNLOCK(rootvp, 0, td);
 2434                         busy = 0;
 2435                 } else
 2436                         VI_UNLOCK(rootvp);
 2437         }
 2438         if (busy)
 2439                 return (EBUSY);
 2440         for (; rootrefs > 0; rootrefs--)
 2441                 vrele(rootvp);
 2442         return (0);
 2443 }
 2444 
 2445 /*
 2446  * Recycle an unused vnode to the front of the free list.
 2447  */
 2448 int
 2449 vrecycle(struct vnode *vp, struct thread *td)
 2450 {
 2451         int recycled;
 2452 
 2453         ASSERT_VOP_LOCKED(vp, "vrecycle");
 2454         recycled = 0;
 2455         VI_LOCK(vp);
 2456         if (vp->v_usecount == 0) {
 2457                 recycled = 1;
 2458                 vgonel(vp);
 2459         }
 2460         VI_UNLOCK(vp);
 2461         return (recycled);
 2462 }
 2463 
 2464 /*
 2465  * Eliminate all activity associated with a vnode
 2466  * in preparation for reuse.
 2467  */
 2468 void
 2469 vgone(struct vnode *vp)
 2470 {
 2471         VI_LOCK(vp);
 2472         vgonel(vp);
 2473         VI_UNLOCK(vp);
 2474 }
 2475 
 2476 /*
 2477  * vgone, with the vp interlock held.
 2478  */
 2479 void
 2480 vgonel(struct vnode *vp)
 2481 {
 2482         struct thread *td;
 2483         int oweinact;
 2484         int active;
 2485         struct mount *mp;
 2486 
 2487         CTR1(KTR_VFS, "vgonel: vp %p", vp);
 2488         ASSERT_VOP_LOCKED(vp, "vgonel");
 2489         ASSERT_VI_LOCKED(vp, "vgonel");
 2490         VNASSERT(vp->v_holdcnt, vp,
 2491             ("vgonel: vp %p has no reference.", vp));
 2492         td = curthread;
 2493 
 2494         /*
 2495          * Don't vgonel if we're already doomed.
 2496          */
 2497         if (vp->v_iflag & VI_DOOMED)
 2498                 return;
 2499         vp->v_iflag |= VI_DOOMED;
 2500         /*
 2501          * Check to see if the vnode is in use.  If so, we have to call
 2502          * VOP_CLOSE() and VOP_INACTIVE().
 2503          */
 2504         active = vp->v_usecount;
 2505         oweinact = (vp->v_iflag & VI_OWEINACT);
 2506         VI_UNLOCK(vp);
 2507         /*
 2508          * Clean out any buffers associated with the vnode.
 2509          * If the flush fails, just toss the buffers.
 2510          */
 2511         mp = NULL;
 2512         if (!TAILQ_EMPTY(&vp->v_bufobj.bo_dirty.bv_hd))
 2513                 (void) vn_start_secondary_write(vp, &mp, V_WAIT);
 2514         if (vinvalbuf(vp, V_SAVE, td, 0, 0) != 0)
 2515                 vinvalbuf(vp, 0, td, 0, 0);
 2516 
 2517         /*
 2518          * If purging an active vnode, it must be closed and
 2519          * deactivated before being reclaimed.
 2520          */
 2521         if (active)
 2522                 VOP_CLOSE(vp, FNONBLOCK, NOCRED, td);
 2523         if (oweinact || active) {
 2524                 VI_LOCK(vp);
 2525                 if ((vp->v_iflag & VI_DOINGINACT) == 0)
 2526                         vinactive(vp, td);
 2527                 VI_UNLOCK(vp);
 2528         }
 2529         /*
 2530          * Reclaim the vnode.
 2531          */
 2532         if (VOP_RECLAIM(vp, td))
 2533                 panic("vgone: cannot reclaim");
 2534         if (mp != NULL)
 2535                 vn_finished_secondary_write(mp);
 2536         VNASSERT(vp->v_object == NULL, vp,
 2537             ("vop_reclaim left v_object vp=%p, tag=%s", vp, vp->v_tag));
 2538         /*
 2539          * Delete from old mount point vnode list.
 2540          */
 2541         delmntque(vp);
 2542         cache_purge(vp);
 2543         /*
 2544          * Done with purge, reset to the standard lock and invalidate
 2545          * the vnode.
 2546          */
 2547         VI_LOCK(vp);
 2548         vp->v_vnlock = &vp->v_lock;
 2549         vp->v_op = &dead_vnodeops;
 2550         vp->v_tag = "none";
 2551         vp->v_type = VBAD;
 2552 }
 2553 
 2554 /*
 2555  * Calculate the total number of references to a special device.
 2556  */
 2557 int
 2558 vcount(struct vnode *vp)
 2559 {
 2560         int count;
 2561 
 2562         dev_lock();
 2563         count = vp->v_rdev->si_usecount;
 2564         dev_unlock();
 2565         return (count);
 2566 }
 2567 
 2568 /*
 2569  * Same as above, but using the struct cdev *as argument
 2570  */
 2571 int
 2572 count_dev(struct cdev *dev)
 2573 {
 2574         int count;
 2575 
 2576         dev_lock();
 2577         count = dev->si_usecount;
 2578         dev_unlock();
 2579         return(count);
 2580 }
 2581 
 2582 /*
 2583  * Print out a description of a vnode.
 2584  */
 2585 static char *typename[] =
 2586 {"VNON", "VREG", "VDIR", "VBLK", "VCHR", "VLNK", "VSOCK", "VFIFO", "VBAD",
 2587  "VMARKER"};
 2588 
 2589 void
 2590 vn_printf(struct vnode *vp, const char *fmt, ...)
 2591 {
 2592         va_list ap;
 2593         char buf[256], buf2[16];
 2594         u_long flags;
 2595 
 2596         va_start(ap, fmt);
 2597         vprintf(fmt, ap);
 2598         va_end(ap);
 2599         printf("%p: ", (void *)vp);
 2600         printf("tag %s, type %s\n", vp->v_tag, typename[vp->v_type]);
 2601         printf("    usecount %d, writecount %d, refcount %d mountedhere %p\n",
 2602             vp->v_usecount, vp->v_writecount, vp->v_holdcnt, vp->v_mountedhere);
 2603         buf[0] = '\0';
 2604         buf[1] = '\0';
 2605         if (vp->v_vflag & VV_ROOT)
 2606                 strlcat(buf, "|VV_ROOT", sizeof(buf));
 2607         if (vp->v_vflag & VV_ISTTY)
 2608                 strlcat(buf, "|VV_ISTTY", sizeof(buf));
 2609         if (vp->v_vflag & VV_NOSYNC)
 2610                 strlcat(buf, "|VV_NOSYNC", sizeof(buf));
 2611         if (vp->v_vflag & VV_CACHEDLABEL)
 2612                 strlcat(buf, "|VV_CACHEDLABEL", sizeof(buf));
 2613         if (vp->v_vflag & VV_TEXT)
 2614                 strlcat(buf, "|VV_TEXT", sizeof(buf));
 2615         if (vp->v_vflag & VV_COPYONWRITE)
 2616                 strlcat(buf, "|VV_COPYONWRITE", sizeof(buf));
 2617         if (vp->v_vflag & VV_SYSTEM)
 2618                 strlcat(buf, "|VV_SYSTEM", sizeof(buf));
 2619         if (vp->v_vflag & VV_PROCDEP)
 2620                 strlcat(buf, "|VV_PROCDEP", sizeof(buf));
 2621         if (vp->v_vflag & VV_NOKNOTE)
 2622                 strlcat(buf, "|VV_NOKNOTE", sizeof(buf));
 2623         if (vp->v_vflag & VV_DELETED)
 2624                 strlcat(buf, "|VV_DELETED", sizeof(buf));
 2625         if (vp->v_vflag & VV_MD)
 2626                 strlcat(buf, "|VV_MD", sizeof(buf));
 2627         flags = vp->v_vflag & ~(VV_ROOT | VV_ISTTY | VV_NOSYNC |
 2628             VV_CACHEDLABEL | VV_TEXT | VV_COPYONWRITE | VV_SYSTEM | VV_PROCDEP |
 2629             VV_NOKNOTE | VV_DELETED | VV_MD);
 2630         if (flags != 0) {
 2631                 snprintf(buf2, sizeof(buf2), "|VV(0x%lx)", flags);
 2632                 strlcat(buf, buf2, sizeof(buf));
 2633         }
 2634         if (vp->v_iflag & VI_MOUNT)
 2635                 strlcat(buf, "|VI_MOUNT", sizeof(buf));
 2636         if (vp->v_iflag & VI_AGE)
 2637                 strlcat(buf, "|VI_AGE", sizeof(buf));
 2638         if (vp->v_iflag & VI_DOOMED)
 2639                 strlcat(buf, "|VI_DOOMED", sizeof(buf));
 2640         if (vp->v_iflag & VI_FREE)
 2641                 strlcat(buf, "|VI_FREE", sizeof(buf));
 2642         if (vp->v_iflag & VI_OBJDIRTY)
 2643                 strlcat(buf, "|VI_OBJDIRTY", sizeof(buf));
 2644         if (vp->v_iflag & VI_DOINGINACT)
 2645                 strlcat(buf, "|VI_DOINGINACT", sizeof(buf));
 2646         if (vp->v_iflag & VI_OWEINACT)
 2647                 strlcat(buf, "|VI_OWEINACT", sizeof(buf));
 2648         flags = vp->v_iflag & ~(VI_MOUNT | VI_AGE | VI_DOOMED | VI_FREE |
 2649             VI_OBJDIRTY | VI_DOINGINACT | VI_OWEINACT);
 2650         if (flags != 0) {
 2651                 snprintf(buf2, sizeof(buf2), "|VI(0x%lx)", flags);
 2652                 strlcat(buf, buf2, sizeof(buf));
 2653         }
 2654         printf("    flags (%s)\n", buf + 1);
 2655         if (mtx_owned(VI_MTX(vp)))
 2656                 printf(" VI_LOCKed");
 2657         if (vp->v_object != NULL)
 2658                 printf("    v_object %p ref %d pages %d\n",
 2659                     vp->v_object, vp->v_object->ref_count,
 2660                     vp->v_object->resident_page_count);
 2661         printf("    ");
 2662         lockmgr_printinfo(vp->v_vnlock);
 2663         printf("\n");
 2664         if (vp->v_data != NULL)
 2665                 VOP_PRINT(vp);
 2666 }
 2667 
 2668 #ifdef DDB
 2669 /*
 2670  * List all of the locked vnodes in the system.
 2671  * Called when debugging the kernel.
 2672  */
 2673 DB_SHOW_COMMAND(lockedvnods, lockedvnodes)
 2674 {
 2675         struct mount *mp, *nmp;
 2676         struct vnode *vp;
 2677 
 2678         /*
 2679          * Note: because this is DDB, we can't obey the locking semantics
 2680          * for these structures, which means we could catch an inconsistent
 2681          * state and dereference a nasty pointer.  Not much to be done
 2682          * about that.
 2683          */
 2684         printf("Locked vnodes\n");
 2685         for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
 2686                 nmp = TAILQ_NEXT(mp, mnt_list);
 2687                 TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
 2688                         if (vp->v_type != VMARKER && VOP_ISLOCKED(vp, NULL))
 2689                                 vprint("", vp);
 2690                 }
 2691                 nmp = TAILQ_NEXT(mp, mnt_list);
 2692         }
 2693 }
 2694 
 2695 /*
 2696  * Show details about the given vnode.
 2697  */
 2698 DB_SHOW_COMMAND(vnode, db_show_vnode)
 2699 {
 2700         struct vnode *vp;
 2701 
 2702         if (!have_addr)
 2703                 return;
 2704         vp = (struct vnode *)addr;
 2705         vn_printf(vp, "vnode ");
 2706 }
 2707 #endif  /* DDB */
 2708 
 2709 /*
 2710  * Fill in a struct xvfsconf based on a struct vfsconf.
 2711  */
 2712 static void
 2713 vfsconf2x(struct vfsconf *vfsp, struct xvfsconf *xvfsp)
 2714 {
 2715 
 2716         strcpy(xvfsp->vfc_name, vfsp->vfc_name);
 2717         xvfsp->vfc_typenum = vfsp->vfc_typenum;
 2718         xvfsp->vfc_refcount = vfsp->vfc_refcount;
 2719         xvfsp->vfc_flags = vfsp->vfc_flags;
 2720         /*
 2721          * These are unused in userland, we keep them
 2722          * to not break binary compatibility.
 2723          */
 2724         xvfsp->vfc_vfsops = NULL;
 2725         xvfsp->vfc_next = NULL;
 2726 }
 2727 
 2728 /*
 2729  * Top level filesystem related information gathering.
 2730  */
 2731 static int
 2732 sysctl_vfs_conflist(SYSCTL_HANDLER_ARGS)
 2733 {
 2734         struct vfsconf *vfsp;
 2735         struct xvfsconf xvfsp;
 2736         int error;
 2737 
 2738         error = 0;
 2739         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
 2740                 bzero(&xvfsp, sizeof(xvfsp));
 2741                 vfsconf2x(vfsp, &xvfsp);
 2742                 error = SYSCTL_OUT(req, &xvfsp, sizeof xvfsp);
 2743                 if (error)
 2744                         break;
 2745         }
 2746         return (error);
 2747 }
 2748 
 2749 SYSCTL_PROC(_vfs, OID_AUTO, conflist, CTLFLAG_RD, NULL, 0, sysctl_vfs_conflist,
 2750     "S,xvfsconf", "List of all configured filesystems");
 2751 
 2752 #ifndef BURN_BRIDGES
 2753 static int      sysctl_ovfs_conf(SYSCTL_HANDLER_ARGS);
 2754 
 2755 static int
 2756 vfs_sysctl(SYSCTL_HANDLER_ARGS)
 2757 {
 2758         int *name = (int *)arg1 - 1;    /* XXX */
 2759         u_int namelen = arg2 + 1;       /* XXX */
 2760         struct vfsconf *vfsp;
 2761         struct xvfsconf xvfsp;
 2762 
 2763         printf("WARNING: userland calling deprecated sysctl, "
 2764             "please rebuild world\n");
 2765 
 2766 #if 1 || defined(COMPAT_PRELITE2)
 2767         /* Resolve ambiguity between VFS_VFSCONF and VFS_GENERIC. */
 2768         if (namelen == 1)
 2769                 return (sysctl_ovfs_conf(oidp, arg1, arg2, req));
 2770 #endif
 2771 
 2772         switch (name[1]) {
 2773         case VFS_MAXTYPENUM:
 2774                 if (namelen != 2)
 2775                         return (ENOTDIR);
 2776                 return (SYSCTL_OUT(req, &maxvfsconf, sizeof(int)));
 2777         case VFS_CONF:
 2778                 if (namelen != 3)
 2779                         return (ENOTDIR);       /* overloaded */
 2780                 TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
 2781                         if (vfsp->vfc_typenum == name[2])
 2782                                 break;
 2783                 if (vfsp == NULL)
 2784                         return (EOPNOTSUPP);
 2785                 bzero(&xvfsp, sizeof(xvfsp));
 2786                 vfsconf2x(vfsp, &xvfsp);
 2787                 return (SYSCTL_OUT(req, &xvfsp, sizeof(xvfsp)));
 2788         }
 2789         return (EOPNOTSUPP);
 2790 }
 2791 
 2792 static SYSCTL_NODE(_vfs, VFS_GENERIC, generic, CTLFLAG_RD | CTLFLAG_SKIP,
 2793         vfs_sysctl, "Generic filesystem");
 2794 
 2795 #if 1 || defined(COMPAT_PRELITE2)
 2796 
 2797 static int
 2798 sysctl_ovfs_conf(SYSCTL_HANDLER_ARGS)
 2799 {
 2800         int error;
 2801         struct vfsconf *vfsp;
 2802         struct ovfsconf ovfs;
 2803 
 2804         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
 2805                 bzero(&ovfs, sizeof(ovfs));
 2806                 ovfs.vfc_vfsops = vfsp->vfc_vfsops;     /* XXX used as flag */
 2807                 strcpy(ovfs.vfc_name, vfsp->vfc_name);
 2808                 ovfs.vfc_index = vfsp->vfc_typenum;
 2809                 ovfs.vfc_refcount = vfsp->vfc_refcount;
 2810                 ovfs.vfc_flags = vfsp->vfc_flags;
 2811                 error = SYSCTL_OUT(req, &ovfs, sizeof ovfs);
 2812                 if (error)
 2813                         return error;
 2814         }
 2815         return 0;
 2816 }
 2817 
 2818 #endif /* 1 || COMPAT_PRELITE2 */
 2819 #endif /* !BURN_BRIDGES */
 2820 
 2821 #define KINFO_VNODESLOP         10
 2822 #ifdef notyet
 2823 /*
 2824  * Dump vnode list (via sysctl).
 2825  */
 2826 /* ARGSUSED */
 2827 static int
 2828 sysctl_vnode(SYSCTL_HANDLER_ARGS)
 2829 {
 2830         struct xvnode *xvn;
 2831         struct thread *td = req->td;
 2832         struct mount *mp;
 2833         struct vnode *vp;
 2834         int error, len, n;
 2835 
 2836         /*
 2837          * Stale numvnodes access is not fatal here.
 2838          */
 2839         req->lock = 0;
 2840         len = (numvnodes + KINFO_VNODESLOP) * sizeof *xvn;
 2841         if (!req->oldptr)
 2842                 /* Make an estimate */
 2843                 return (SYSCTL_OUT(req, 0, len));
 2844 
 2845         error = sysctl_wire_old_buffer(req, 0);
 2846         if (error != 0)
 2847                 return (error);
 2848         xvn = malloc(len, M_TEMP, M_ZERO | M_WAITOK);
 2849         n = 0;
 2850         mtx_lock(&mountlist_mtx);
 2851         TAILQ_FOREACH(mp, &mountlist, mnt_list) {
 2852                 if (vfs_busy(mp, LK_NOWAIT, &mountlist_mtx, td))
 2853                         continue;
 2854                 MNT_ILOCK(mp);
 2855                 TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
 2856                         if (n == len)
 2857                                 break;
 2858                         vref(vp);
 2859                         xvn[n].xv_size = sizeof *xvn;
 2860                         xvn[n].xv_vnode = vp;
 2861                         xvn[n].xv_id = 0;       /* XXX compat */
 2862 #define XV_COPY(field) xvn[n].xv_##field = vp->v_##field
 2863                         XV_COPY(usecount);
 2864                         XV_COPY(writecount);
 2865                         XV_COPY(holdcnt);
 2866                         XV_COPY(mount);
 2867                         XV_COPY(numoutput);
 2868                         XV_COPY(type);
 2869 #undef XV_COPY
 2870                         xvn[n].xv_flag = vp->v_vflag;
 2871 
 2872                         switch (vp->v_type) {
 2873                         case VREG:
 2874                         case VDIR:
 2875                         case VLNK:
 2876                                 break;
 2877                         case VBLK:
 2878                         case VCHR:
 2879                                 if (vp->v_rdev == NULL) {
 2880                                         vrele(vp);
 2881                                         continue;
 2882                                 }
 2883                                 xvn[n].xv_dev = dev2udev(vp->v_rdev);
 2884                                 break;
 2885                         case VSOCK:
 2886                                 xvn[n].xv_socket = vp->v_socket;
 2887                                 break;
 2888                         case VFIFO:
 2889                                 xvn[n].xv_fifo = vp->v_fifoinfo;
 2890                                 break;
 2891                         case VNON:
 2892                         case VBAD:
 2893                         default:
 2894                                 /* shouldn't happen? */
 2895                                 vrele(vp);
 2896                                 continue;
 2897                         }
 2898                         vrele(vp);
 2899                         ++n;
 2900                 }
 2901                 MNT_IUNLOCK(mp);
 2902                 mtx_lock(&mountlist_mtx);
 2903                 vfs_unbusy(mp, td);
 2904                 if (n == len)
 2905                         break;
 2906         }
 2907         mtx_unlock(&mountlist_mtx);
 2908 
 2909         error = SYSCTL_OUT(req, xvn, n * sizeof *xvn);
 2910         free(xvn, M_TEMP);
 2911         return (error);
 2912 }
 2913 
 2914 SYSCTL_PROC(_kern, KERN_VNODE, vnode, CTLTYPE_OPAQUE|CTLFLAG_RD,
 2915         0, 0, sysctl_vnode, "S,xvnode", "");
 2916 #endif
 2917 
 2918 /*
 2919  * Unmount all filesystems. The list is traversed in reverse order
 2920  * of mounting to avoid dependencies.
 2921  */
 2922 void
 2923 vfs_unmountall(void)
 2924 {
 2925         struct mount *mp;
 2926         struct thread *td;
 2927         int error;
 2928 
 2929         KASSERT(curthread != NULL, ("vfs_unmountall: NULL curthread"));
 2930         td = curthread;
 2931         /*
 2932          * Since this only runs when rebooting, it is not interlocked.
 2933          */
 2934         while(!TAILQ_EMPTY(&mountlist)) {
 2935                 mp = TAILQ_LAST(&mountlist, mntlist);
 2936                 error = dounmount(mp, MNT_FORCE, td);
 2937                 if (error) {
 2938                         TAILQ_REMOVE(&mountlist, mp, mnt_list);
 2939                         /*
 2940                          * XXX: Due to the way in which we mount the root
 2941                          * file system off of devfs, devfs will generate a
 2942                          * "busy" warning when we try to unmount it before
 2943                          * the root.  Don't print a warning as a result in
 2944                          * order to avoid false positive errors that may
 2945                          * cause needless upset.
 2946                          */
 2947                         if (strcmp(mp->mnt_vfc->vfc_name, "devfs") != 0) {
 2948                                 printf("unmount of %s failed (",
 2949                                     mp->mnt_stat.f_mntonname);
 2950                                 if (error == EBUSY)
 2951                                         printf("BUSY)\n");
 2952                                 else
 2953                                         printf("%d)\n", error);
 2954                         }
 2955                 } else {
 2956                         /* The unmount has removed mp from the mountlist */
 2957                 }
 2958         }
 2959 }
 2960 
 2961 /*
 2962  * perform msync on all vnodes under a mount point
 2963  * the mount point must be locked.
 2964  */
 2965 void
 2966 vfs_msync(struct mount *mp, int flags)
 2967 {
 2968         struct vnode *vp, *mvp;
 2969         struct vm_object *obj;
 2970 
 2971         MNT_ILOCK(mp);
 2972         MNT_VNODE_FOREACH(vp, mp, mvp) {
 2973                 VI_LOCK(vp);
 2974                 if ((vp->v_iflag & VI_OBJDIRTY) &&
 2975                     (flags == MNT_WAIT || VOP_ISLOCKED(vp, NULL) == 0)) {
 2976                         MNT_IUNLOCK(mp);
 2977                         if (!vget(vp,
 2978                             LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK,
 2979                             curthread)) {
 2980                                 if (vp->v_vflag & VV_NOSYNC) {  /* unlinked */
 2981                                         vput(vp);
 2982                                         MNT_ILOCK(mp);
 2983                                         continue;
 2984                                 }
 2985 
 2986                                 obj = vp->v_object;
 2987                                 if (obj != NULL) {
 2988                                         VM_OBJECT_LOCK(obj);
 2989                                         vm_object_page_clean(obj, 0, 0,
 2990                                             flags == MNT_WAIT ?
 2991                                             OBJPC_SYNC : OBJPC_NOSYNC);
 2992                                         VM_OBJECT_UNLOCK(obj);
 2993                                 }
 2994                                 vput(vp);
 2995                         }
 2996                         MNT_ILOCK(mp);
 2997                 } else
 2998                         VI_UNLOCK(vp);
 2999         }
 3000         MNT_IUNLOCK(mp);
 3001 }
 3002 
 3003 /*
 3004  * Mark a vnode as free, putting it up for recycling.
 3005  */
 3006 static void
 3007 vfree(struct vnode *vp)
 3008 {
 3009 
 3010         CTR1(KTR_VFS, "vfree vp %p", vp);
 3011         ASSERT_VI_LOCKED(vp, "vfree");
 3012         mtx_lock(&vnode_free_list_mtx);
 3013         VNASSERT(vp->v_op != NULL, vp, ("vfree: vnode already reclaimed."));
 3014         VNASSERT((vp->v_iflag & VI_FREE) == 0, vp, ("vnode already free"));
 3015         VNASSERT(VSHOULDFREE(vp), vp, ("vfree: freeing when we shouldn't"));
 3016         VNASSERT((vp->v_iflag & VI_DOOMED) == 0, vp,
 3017             ("vfree: Freeing doomed vnode"));
 3018         if (vp->v_iflag & VI_AGE) {
 3019                 TAILQ_INSERT_HEAD(&vnode_free_list, vp, v_freelist);
 3020         } else {
 3021                 TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
 3022         }
 3023         freevnodes++;
 3024         vp->v_iflag &= ~VI_AGE;
 3025         vp->v_iflag |= VI_FREE;
 3026         mtx_unlock(&vnode_free_list_mtx);
 3027 }
 3028 
 3029 /*
 3030  * Opposite of vfree() - mark a vnode as in use.
 3031  */
 3032 static void
 3033 vbusy(struct vnode *vp)
 3034 {
 3035         CTR1(KTR_VFS, "vbusy vp %p", vp);
 3036         ASSERT_VI_LOCKED(vp, "vbusy");
 3037         VNASSERT((vp->v_iflag & VI_FREE) != 0, vp, ("vnode not free"));
 3038         VNASSERT(vp->v_op != NULL, vp, ("vbusy: vnode already reclaimed."));
 3039 
 3040         mtx_lock(&vnode_free_list_mtx);
 3041         TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
 3042         freevnodes--;
 3043         vp->v_iflag &= ~(VI_FREE|VI_AGE);
 3044         mtx_unlock(&vnode_free_list_mtx);
 3045 }
 3046 
 3047 /*
 3048  * Initalize per-vnode helper structure to hold poll-related state.
 3049  */
 3050 void
 3051 v_addpollinfo(struct vnode *vp)
 3052 {
 3053         struct vpollinfo *vi;
 3054 
 3055         vi = uma_zalloc(vnodepoll_zone, M_WAITOK);
 3056         if (vp->v_pollinfo != NULL) {
 3057                 uma_zfree(vnodepoll_zone, vi);
 3058                 return;
 3059         }
 3060         vp->v_pollinfo = vi;
 3061         mtx_init(&vp->v_pollinfo->vpi_lock, "vnode pollinfo", NULL, MTX_DEF);
 3062         knlist_init(&vp->v_pollinfo->vpi_selinfo.si_note, vp, vfs_knllock,
 3063             vfs_knlunlock, vfs_knllocked);
 3064 }
 3065 
 3066 /*
 3067  * Record a process's interest in events which might happen to
 3068  * a vnode.  Because poll uses the historic select-style interface
 3069  * internally, this routine serves as both the ``check for any
 3070  * pending events'' and the ``record my interest in future events''
 3071  * functions.  (These are done together, while the lock is held,
 3072  * to avoid race conditions.)
 3073  */
 3074 int
 3075 vn_pollrecord(struct vnode *vp, struct thread *td, int events)
 3076 {
 3077 
 3078         if (vp->v_pollinfo == NULL)
 3079                 v_addpollinfo(vp);
 3080         mtx_lock(&vp->v_pollinfo->vpi_lock);
 3081         if (vp->v_pollinfo->vpi_revents & events) {
 3082                 /*
 3083                  * This leaves events we are not interested
 3084                  * in available for the other process which
 3085                  * which presumably had requested them
 3086                  * (otherwise they would never have been
 3087                  * recorded).
 3088                  */
 3089                 events &= vp->v_pollinfo->vpi_revents;
 3090                 vp->v_pollinfo->vpi_revents &= ~events;
 3091 
 3092                 mtx_unlock(&vp->v_pollinfo->vpi_lock);
 3093                 return events;
 3094         }
 3095         vp->v_pollinfo->vpi_events |= events;
 3096         selrecord(td, &vp->v_pollinfo->vpi_selinfo);
 3097         mtx_unlock(&vp->v_pollinfo->vpi_lock);
 3098         return 0;
 3099 }
 3100 
 3101 /*
 3102  * Routine to create and manage a filesystem syncer vnode.
 3103  */
 3104 #define sync_close ((int (*)(struct  vop_close_args *))nullop)
 3105 static int      sync_fsync(struct  vop_fsync_args *);
 3106 static int      sync_inactive(struct  vop_inactive_args *);
 3107 static int      sync_reclaim(struct  vop_reclaim_args *);
 3108 
 3109 static struct vop_vector sync_vnodeops = {
 3110         .vop_bypass =   VOP_EOPNOTSUPP,
 3111         .vop_close =    sync_close,             /* close */
 3112         .vop_fsync =    sync_fsync,             /* fsync */
 3113         .vop_inactive = sync_inactive,  /* inactive */
 3114         .vop_reclaim =  sync_reclaim,   /* reclaim */
 3115         .vop_lock1 =    vop_stdlock,    /* lock */
 3116         .vop_unlock =   vop_stdunlock,  /* unlock */
 3117         .vop_islocked = vop_stdislocked,        /* islocked */
 3118 };
 3119 
 3120 /*
 3121  * Create a new filesystem syncer vnode for the specified mount point.
 3122  */
 3123 int
 3124 vfs_allocate_syncvnode(struct mount *mp)
 3125 {
 3126         struct vnode *vp;
 3127         static long start, incr, next;
 3128         int error;
 3129 
 3130         /* Allocate a new vnode */
 3131         if ((error = getnewvnode("syncer", mp, &sync_vnodeops, &vp)) != 0) {
 3132                 mp->mnt_syncer = NULL;
 3133                 return (error);
 3134         }
 3135         vp->v_type = VNON;
 3136         error = insmntque(vp, mp);
 3137         if (error != 0)
 3138                 panic("vfs_allocate_syncvnode: insmntque failed");
 3139         /*
 3140          * Place the vnode onto the syncer worklist. We attempt to
 3141          * scatter them about on the list so that they will go off
 3142          * at evenly distributed times even if all the filesystems
 3143          * are mounted at once.
 3144          */
 3145         next += incr;
 3146         if (next == 0 || next > syncer_maxdelay) {
 3147                 start /= 2;
 3148                 incr /= 2;
 3149                 if (start == 0) {
 3150                         start = syncer_maxdelay / 2;
 3151                         incr = syncer_maxdelay;
 3152                 }
 3153                 next = start;
 3154         }
 3155         VI_LOCK(vp);
 3156         vn_syncer_add_to_worklist(&vp->v_bufobj,
 3157             syncdelay > 0 ? next % syncdelay : 0);
 3158         /* XXX - vn_syncer_add_to_worklist() also grabs and drops sync_mtx. */
 3159         mtx_lock(&sync_mtx);
 3160         sync_vnode_count++;
 3161         mtx_unlock(&sync_mtx);
 3162         VI_UNLOCK(vp);
 3163         mp->mnt_syncer = vp;
 3164         return (0);
 3165 }
 3166 
 3167 /*
 3168  * Do a lazy sync of the filesystem.
 3169  */
 3170 static int
 3171 sync_fsync(struct vop_fsync_args *ap)
 3172 {
 3173         struct vnode *syncvp = ap->a_vp;
 3174         struct mount *mp = syncvp->v_mount;
 3175         struct thread *td = ap->a_td;
 3176         int error;
 3177         struct bufobj *bo;
 3178 
 3179         /*
 3180          * We only need to do something if this is a lazy evaluation.
 3181          */
 3182         if (ap->a_waitfor != MNT_LAZY)
 3183                 return (0);
 3184 
 3185         /*
 3186          * Move ourselves to the back of the sync list.
 3187          */
 3188         bo = &syncvp->v_bufobj;
 3189         BO_LOCK(bo);
 3190         vn_syncer_add_to_worklist(bo, syncdelay);
 3191         BO_UNLOCK(bo);
 3192 
 3193         /*
 3194          * Walk the list of vnodes pushing all that are dirty and
 3195          * not already on the sync list.
 3196          */
 3197         mtx_lock(&mountlist_mtx);
 3198         if (vfs_busy(mp, LK_EXCLUSIVE | LK_NOWAIT, &mountlist_mtx, td) != 0) {
 3199                 mtx_unlock(&mountlist_mtx);
 3200                 return (0);
 3201         }
 3202         if (vn_start_write(NULL, &mp, V_NOWAIT) != 0) {
 3203                 vfs_unbusy(mp, td);
 3204                 return (0);
 3205         }
 3206         MNT_ILOCK(mp);
 3207         mp->mnt_noasync++;
 3208         mp->mnt_kern_flag &= ~MNTK_ASYNC;
 3209         MNT_IUNLOCK(mp);
 3210         vfs_msync(mp, MNT_NOWAIT);
 3211         error = VFS_SYNC(mp, MNT_LAZY, td);
 3212         MNT_ILOCK(mp);
 3213         mp->mnt_noasync--;
 3214         if ((mp->mnt_flag & MNT_ASYNC) != 0 && mp->mnt_noasync == 0)
 3215                 mp->mnt_kern_flag |= MNTK_ASYNC;
 3216         MNT_IUNLOCK(mp);
 3217         vn_finished_write(mp);
 3218         vfs_unbusy(mp, td);
 3219         return (error);
 3220 }
 3221 
 3222 /*
 3223  * The syncer vnode is no referenced.
 3224  */
 3225 static int
 3226 sync_inactive(struct vop_inactive_args *ap)
 3227 {
 3228 
 3229         vgone(ap->a_vp);
 3230         return (0);
 3231 }
 3232 
 3233 /*
 3234  * The syncer vnode is no longer needed and is being decommissioned.
 3235  *
 3236  * Modifications to the worklist must be protected by sync_mtx.
 3237  */
 3238 static int
 3239 sync_reclaim(struct vop_reclaim_args *ap)
 3240 {
 3241         struct vnode *vp = ap->a_vp;
 3242         struct bufobj *bo;
 3243 
 3244         VI_LOCK(vp);
 3245         bo = &vp->v_bufobj;
 3246         vp->v_mount->mnt_syncer = NULL;
 3247         if (bo->bo_flag & BO_ONWORKLST) {
 3248                 mtx_lock(&sync_mtx);
 3249                 LIST_REMOVE(bo, bo_synclist);
 3250                 syncer_worklist_len--;
 3251                 sync_vnode_count--;
 3252                 mtx_unlock(&sync_mtx);
 3253                 bo->bo_flag &= ~BO_ONWORKLST;
 3254         }
 3255         VI_UNLOCK(vp);
 3256 
 3257         return (0);
 3258 }
 3259 
 3260 /*
 3261  * Check if vnode represents a disk device
 3262  */
 3263 int
 3264 vn_isdisk(struct vnode *vp, int *errp)
 3265 {
 3266         int error;
 3267 
 3268         error = 0;
 3269         dev_lock();
 3270         if (vp->v_type != VCHR)
 3271                 error = ENOTBLK;
 3272         else if (vp->v_rdev == NULL)
 3273                 error = ENXIO;
 3274         else if (vp->v_rdev->si_devsw == NULL)
 3275                 error = ENXIO;
 3276         else if (!(vp->v_rdev->si_devsw->d_flags & D_DISK))
 3277                 error = ENOTBLK;
 3278         dev_unlock();
 3279         if (errp != NULL)
 3280                 *errp = error;
 3281         return (error == 0);
 3282 }
 3283 
 3284 /*
 3285  * Common filesystem object access control check routine.  Accepts a
 3286  * vnode's type, "mode", uid and gid, requested access mode, credentials,
 3287  * and optional call-by-reference privused argument allowing vaccess()
 3288  * to indicate to the caller whether privilege was used to satisfy the
 3289  * request (obsoleted).  Returns 0 on success, or an errno on failure.
 3290  *
 3291  * The ifdef'd CAPABILITIES version is here for reference, but is not
 3292  * actually used.
 3293  */
 3294 int
 3295 vaccess(enum vtype type, mode_t file_mode, uid_t file_uid, gid_t file_gid,
 3296     mode_t acc_mode, struct ucred *cred, int *privused)
 3297 {
 3298         mode_t dac_granted;
 3299         mode_t priv_granted;
 3300 
 3301         /*
 3302          * Look for a normal, non-privileged way to access the file/directory
 3303          * as requested.  If it exists, go with that.
 3304          */
 3305 
 3306         if (privused != NULL)
 3307                 *privused = 0;
 3308 
 3309         dac_granted = 0;
 3310 
 3311         /* Check the owner. */
 3312         if (cred->cr_uid == file_uid) {
 3313                 dac_granted |= VADMIN;
 3314                 if (file_mode & S_IXUSR)
 3315                         dac_granted |= VEXEC;
 3316                 if (file_mode & S_IRUSR)
 3317                         dac_granted |= VREAD;
 3318                 if (file_mode & S_IWUSR)
 3319                         dac_granted |= (VWRITE | VAPPEND);
 3320 
 3321                 if ((acc_mode & dac_granted) == acc_mode)
 3322                         return (0);
 3323 
 3324                 goto privcheck;
 3325         }
 3326 
 3327         /* Otherwise, check the groups (first match) */
 3328         if (groupmember(file_gid, cred)) {
 3329                 if (file_mode & S_IXGRP)
 3330                         dac_granted |= VEXEC;
 3331                 if (file_mode & S_IRGRP)
 3332                         dac_granted |= VREAD;
 3333                 if (file_mode & S_IWGRP)
 3334                         dac_granted |= (VWRITE | VAPPEND);
 3335 
 3336                 if ((acc_mode & dac_granted) == acc_mode)
 3337                         return (0);
 3338 
 3339                 goto privcheck;
 3340         }
 3341 
 3342         /* Otherwise, check everyone else. */
 3343         if (file_mode & S_IXOTH)
 3344                 dac_granted |= VEXEC;
 3345         if (file_mode & S_IROTH)
 3346                 dac_granted |= VREAD;
 3347         if (file_mode & S_IWOTH)
 3348                 dac_granted |= (VWRITE | VAPPEND);
 3349         if ((acc_mode & dac_granted) == acc_mode)
 3350                 return (0);
 3351 
 3352 privcheck:
 3353         /*
 3354          * Build a privilege mask to determine if the set of privileges
 3355          * satisfies the requirements when combined with the granted mask
 3356          * from above.  For each privilege, if the privilege is required,
 3357          * bitwise or the request type onto the priv_granted mask.
 3358          */
 3359         priv_granted = 0;
 3360 
 3361         if (type == VDIR) {
 3362                 /*
 3363                  * For directories, use PRIV_VFS_LOOKUP to satisfy VEXEC
 3364                  * requests, instead of PRIV_VFS_EXEC.
 3365                  */
 3366                 if ((acc_mode & VEXEC) && ((dac_granted & VEXEC) == 0) &&
 3367                     !priv_check_cred(cred, PRIV_VFS_LOOKUP, 0))
 3368                         priv_granted |= VEXEC;
 3369         } else {
 3370                 if ((acc_mode & VEXEC) && ((dac_granted & VEXEC) == 0) &&
 3371                     !priv_check_cred(cred, PRIV_VFS_EXEC, 0))
 3372                         priv_granted |= VEXEC;
 3373         }
 3374 
 3375         if ((acc_mode & VREAD) && ((dac_granted & VREAD) == 0) &&
 3376             !priv_check_cred(cred, PRIV_VFS_READ, 0))
 3377                 priv_granted |= VREAD;
 3378 
 3379         if ((acc_mode & VWRITE) && ((dac_granted & VWRITE) == 0) &&
 3380             !priv_check_cred(cred, PRIV_VFS_WRITE, 0))
 3381                 priv_granted |= (VWRITE | VAPPEND);
 3382 
 3383         if ((acc_mode & VADMIN) && ((dac_granted & VADMIN) == 0) &&
 3384             !priv_check_cred(cred, PRIV_VFS_ADMIN, 0))
 3385                 priv_granted |= VADMIN;
 3386 
 3387         if ((acc_mode & (priv_granted | dac_granted)) == acc_mode) {
 3388                 /* XXX audit: privilege used */
 3389                 if (privused != NULL)
 3390                         *privused = 1;
 3391                 return (0);
 3392         }
 3393 
 3394         return ((acc_mode & VADMIN) ? EPERM : EACCES);
 3395 }
 3396 
 3397 /*
 3398  * Credential check based on process requesting service, and per-attribute
 3399  * permissions.
 3400  */
 3401 int
 3402 extattr_check_cred(struct vnode *vp, int attrnamespace, struct ucred *cred,
 3403     struct thread *td, int access)
 3404 {
 3405 
 3406         /*
 3407          * Kernel-invoked always succeeds.
 3408          */
 3409         if (cred == NOCRED)
 3410                 return (0);
 3411 
 3412         /*
 3413          * Do not allow privileged processes in jail to directly manipulate
 3414          * system attributes.
 3415          */
 3416         switch (attrnamespace) {
 3417         case EXTATTR_NAMESPACE_SYSTEM:
 3418                 /* Potentially should be: return (EPERM); */
 3419                 return (priv_check_cred(cred, PRIV_VFS_EXTATTR_SYSTEM, 0));
 3420         case EXTATTR_NAMESPACE_USER:
 3421                 return (VOP_ACCESS(vp, access, cred, td));
 3422         default:
 3423                 return (EPERM);
 3424         }
 3425 }
 3426 
 3427 #ifdef DEBUG_VFS_LOCKS
 3428 /*
 3429  * This only exists to supress warnings from unlocked specfs accesses.  It is
 3430  * no longer ok to have an unlocked VFS.
 3431  */
 3432 #define IGNORE_LOCK(vp) ((vp)->v_type == VCHR || (vp)->v_type == VBAD)
 3433 
 3434 int vfs_badlock_ddb = 1;        /* Drop into debugger on violation. */
 3435 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_ddb, CTLFLAG_RW, &vfs_badlock_ddb, 0, "");
 3436 
 3437 int vfs_badlock_mutex = 1;      /* Check for interlock across VOPs. */
 3438 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_mutex, CTLFLAG_RW, &vfs_badlock_mutex, 0, "");
 3439 
 3440 int vfs_badlock_print = 1;      /* Print lock violations. */
 3441 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_print, CTLFLAG_RW, &vfs_badlock_print, 0, "");
 3442 
 3443 #ifdef KDB
 3444 int vfs_badlock_backtrace = 1;  /* Print backtrace at lock violations. */
 3445 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_backtrace, CTLFLAG_RW, &vfs_badlock_backtrace, 0, "");
 3446 #endif
 3447 
 3448 static void
 3449 vfs_badlock(const char *msg, const char *str, struct vnode *vp)
 3450 {
 3451 
 3452 #ifdef KDB
 3453         if (vfs_badlock_backtrace)
 3454                 kdb_backtrace();
 3455 #endif
 3456         if (vfs_badlock_print)
 3457                 printf("%s: %p %s\n", str, (void *)vp, msg);
 3458         if (vfs_badlock_ddb)
 3459                 kdb_enter("lock violation");
 3460 }
 3461 
 3462 void
 3463 assert_vi_locked(struct vnode *vp, const char *str)
 3464 {
 3465 
 3466         if (vfs_badlock_mutex && !mtx_owned(VI_MTX(vp)))
 3467                 vfs_badlock("interlock is not locked but should be", str, vp);
 3468 }
 3469 
 3470 void
 3471 assert_vi_unlocked(struct vnode *vp, const char *str)
 3472 {
 3473 
 3474         if (vfs_badlock_mutex && mtx_owned(VI_MTX(vp)))
 3475                 vfs_badlock("interlock is locked but should not be", str, vp);
 3476 }
 3477 
 3478 void
 3479 assert_vop_locked(struct vnode *vp, const char *str)
 3480 {
 3481 
 3482         if (vp && !IGNORE_LOCK(vp) && VOP_ISLOCKED(vp, NULL) == 0)
 3483                 vfs_badlock("is not locked but should be", str, vp);
 3484 }
 3485 
 3486 void
 3487 assert_vop_unlocked(struct vnode *vp, const char *str)
 3488 {
 3489 
 3490         if (vp && !IGNORE_LOCK(vp) &&
 3491             VOP_ISLOCKED(vp, curthread) == LK_EXCLUSIVE)
 3492                 vfs_badlock("is locked but should not be", str, vp);
 3493 }
 3494 
 3495 void
 3496 assert_vop_elocked(struct vnode *vp, const char *str)
 3497 {
 3498 
 3499         if (vp && !IGNORE_LOCK(vp) &&
 3500             VOP_ISLOCKED(vp, curthread) != LK_EXCLUSIVE)
 3501                 vfs_badlock("is not exclusive locked but should be", str, vp);
 3502 }
 3503 
 3504 #if 0
 3505 void
 3506 assert_vop_elocked_other(struct vnode *vp, const char *str)
 3507 {
 3508 
 3509         if (vp && !IGNORE_LOCK(vp) &&
 3510             VOP_ISLOCKED(vp, curthread) != LK_EXCLOTHER)
 3511                 vfs_badlock("is not exclusive locked by another thread",
 3512                     str, vp);
 3513 }
 3514 
 3515 void
 3516 assert_vop_slocked(struct vnode *vp, const char *str)
 3517 {
 3518 
 3519         if (vp && !IGNORE_LOCK(vp) &&
 3520             VOP_ISLOCKED(vp, curthread) != LK_SHARED)
 3521                 vfs_badlock("is not locked shared but should be", str, vp);
 3522 }
 3523 #endif /* 0 */
 3524 #endif /* DEBUG_VFS_LOCKS */
 3525 
 3526 void
 3527 vop_rename_pre(void *ap)
 3528 {
 3529         struct vop_rename_args *a = ap;
 3530 
 3531 #ifdef DEBUG_VFS_LOCKS
 3532         if (a->a_tvp)
 3533                 ASSERT_VI_UNLOCKED(a->a_tvp, "VOP_RENAME");
 3534         ASSERT_VI_UNLOCKED(a->a_tdvp, "VOP_RENAME");
 3535         ASSERT_VI_UNLOCKED(a->a_fvp, "VOP_RENAME");
 3536         ASSERT_VI_UNLOCKED(a->a_fdvp, "VOP_RENAME");
 3537 
 3538         /* Check the source (from). */
 3539         if (a->a_tdvp != a->a_fdvp && a->a_tvp != a->a_fdvp)
 3540                 ASSERT_VOP_UNLOCKED(a->a_fdvp, "vop_rename: fdvp locked");
 3541         if (a->a_tvp != a->a_fvp)
 3542                 ASSERT_VOP_UNLOCKED(a->a_fvp, "vop_rename: fvp locked");
 3543 
 3544         /* Check the target. */
 3545         if (a->a_tvp)
 3546                 ASSERT_VOP_LOCKED(a->a_tvp, "vop_rename: tvp not locked");
 3547         ASSERT_VOP_LOCKED(a->a_tdvp, "vop_rename: tdvp not locked");
 3548 #endif
 3549         if (a->a_tdvp != a->a_fdvp)
 3550                 vhold(a->a_fdvp);
 3551         if (a->a_tvp != a->a_fvp)
 3552                 vhold(a->a_fvp);
 3553         vhold(a->a_tdvp);
 3554         if (a->a_tvp)
 3555                 vhold(a->a_tvp);
 3556 }
 3557 
 3558 void
 3559 vop_strategy_pre(void *ap)
 3560 {
 3561 #ifdef DEBUG_VFS_LOCKS
 3562         struct vop_strategy_args *a;
 3563         struct buf *bp;
 3564 
 3565         a = ap;
 3566         bp = a->a_bp;
 3567 
 3568         /*
 3569          * Cluster ops lock their component buffers but not the IO container.
 3570          */
 3571         if ((bp->b_flags & B_CLUSTER) != 0)
 3572                 return;
 3573 
 3574         if (BUF_REFCNT(bp) < 1) {
 3575                 if (vfs_badlock_print)
 3576                         printf(
 3577                             "VOP_STRATEGY: bp is not locked but should be\n");
 3578                 if (vfs_badlock_ddb)
 3579                         kdb_enter("lock violation");
 3580         }
 3581 #endif
 3582 }
 3583 
 3584 void
 3585 vop_lookup_pre(void *ap)
 3586 {
 3587 #ifdef DEBUG_VFS_LOCKS
 3588         struct vop_lookup_args *a;
 3589         struct vnode *dvp;
 3590 
 3591         a = ap;
 3592         dvp = a->a_dvp;
 3593         ASSERT_VI_UNLOCKED(dvp, "VOP_LOOKUP");
 3594         ASSERT_VOP_LOCKED(dvp, "VOP_LOOKUP");
 3595 #endif
 3596 }
 3597 
 3598 void
 3599 vop_lookup_post(void *ap, int rc)
 3600 {
 3601 #ifdef DEBUG_VFS_LOCKS
 3602         struct vop_lookup_args *a;
 3603         struct vnode *dvp;
 3604         struct vnode *vp;
 3605 
 3606         a = ap;
 3607         dvp = a->a_dvp;
 3608         vp = *(a->a_vpp);
 3609 
 3610         ASSERT_VI_UNLOCKED(dvp, "VOP_LOOKUP");
 3611         ASSERT_VOP_LOCKED(dvp, "VOP_LOOKUP");
 3612 
 3613         if (!rc)
 3614                 ASSERT_VOP_LOCKED(vp, "VOP_LOOKUP (child)");
 3615 #endif
 3616 }
 3617 
 3618 void
 3619 vop_lock_pre(void *ap)
 3620 {
 3621 #ifdef DEBUG_VFS_LOCKS
 3622         struct vop_lock1_args *a = ap;
 3623 
 3624         if ((a->a_flags & LK_INTERLOCK) == 0)
 3625                 ASSERT_VI_UNLOCKED(a->a_vp, "VOP_LOCK");
 3626         else
 3627                 ASSERT_VI_LOCKED(a->a_vp, "VOP_LOCK");
 3628 #endif
 3629 }
 3630 
 3631 void
 3632 vop_lock_post(void *ap, int rc)
 3633 {
 3634 #ifdef DEBUG_VFS_LOCKS
 3635         struct vop_lock1_args *a = ap;
 3636 
 3637         ASSERT_VI_UNLOCKED(a->a_vp, "VOP_LOCK");
 3638         if (rc == 0)
 3639                 ASSERT_VOP_LOCKED(a->a_vp, "VOP_LOCK");
 3640 #endif
 3641 }
 3642 
 3643 void
 3644 vop_unlock_pre(void *ap)
 3645 {
 3646 #ifdef DEBUG_VFS_LOCKS
 3647         struct vop_unlock_args *a = ap;
 3648 
 3649         if (a->a_flags & LK_INTERLOCK)
 3650                 ASSERT_VI_LOCKED(a->a_vp, "VOP_UNLOCK");
 3651         ASSERT_VOP_LOCKED(a->a_vp, "VOP_UNLOCK");
 3652 #endif
 3653 }
 3654 
 3655 void
 3656 vop_unlock_post(void *ap, int rc)
 3657 {
 3658 #ifdef DEBUG_VFS_LOCKS
 3659         struct vop_unlock_args *a = ap;
 3660 
 3661         if (a->a_flags & LK_INTERLOCK)
 3662                 ASSERT_VI_UNLOCKED(a->a_vp, "VOP_UNLOCK");
 3663 #endif
 3664 }
 3665 
 3666 void
 3667 vop_create_post(void *ap, int rc)
 3668 {
 3669         struct vop_create_args *a = ap;
 3670 
 3671         if (!rc)
 3672                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 3673 }
 3674 
 3675 void
 3676 vop_link_post(void *ap, int rc)
 3677 {
 3678         struct vop_link_args *a = ap;
 3679 
 3680         if (!rc) {
 3681                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_LINK);
 3682                 VFS_KNOTE_LOCKED(a->a_tdvp, NOTE_WRITE);
 3683         }
 3684 }
 3685 
 3686 void
 3687 vop_mkdir_post(void *ap, int rc)
 3688 {
 3689         struct vop_mkdir_args *a = ap;
 3690 
 3691         if (!rc)
 3692                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE | NOTE_LINK);
 3693 }
 3694 
 3695 void
 3696 vop_mknod_post(void *ap, int rc)
 3697 {
 3698         struct vop_mknod_args *a = ap;
 3699 
 3700         if (!rc)
 3701                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 3702 }
 3703 
 3704 void
 3705 vop_remove_post(void *ap, int rc)
 3706 {
 3707         struct vop_remove_args *a = ap;
 3708 
 3709         if (!rc) {
 3710                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 3711                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_DELETE);
 3712         }
 3713 }
 3714 
 3715 void
 3716 vop_rename_post(void *ap, int rc)
 3717 {
 3718         struct vop_rename_args *a = ap;
 3719 
 3720         if (!rc) {
 3721                 VFS_KNOTE_UNLOCKED(a->a_fdvp, NOTE_WRITE);
 3722                 VFS_KNOTE_UNLOCKED(a->a_tdvp, NOTE_WRITE);
 3723                 VFS_KNOTE_UNLOCKED(a->a_fvp, NOTE_RENAME);
 3724                 if (a->a_tvp)
 3725                         VFS_KNOTE_UNLOCKED(a->a_tvp, NOTE_DELETE);
 3726         }
 3727         if (a->a_tdvp != a->a_fdvp)
 3728                 vdrop(a->a_fdvp);
 3729         if (a->a_tvp != a->a_fvp)
 3730                 vdrop(a->a_fvp);
 3731         vdrop(a->a_tdvp);
 3732         if (a->a_tvp)
 3733                 vdrop(a->a_tvp);
 3734 }
 3735 
 3736 void
 3737 vop_rmdir_post(void *ap, int rc)
 3738 {
 3739         struct vop_rmdir_args *a = ap;
 3740 
 3741         if (!rc) {
 3742                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE | NOTE_LINK);
 3743                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_DELETE);
 3744         }
 3745 }
 3746 
 3747 void
 3748 vop_setattr_post(void *ap, int rc)
 3749 {
 3750         struct vop_setattr_args *a = ap;
 3751 
 3752         if (!rc)
 3753                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_ATTRIB);
 3754 }
 3755 
 3756 void
 3757 vop_symlink_post(void *ap, int rc)
 3758 {
 3759         struct vop_symlink_args *a = ap;
 3760 
 3761         if (!rc)
 3762                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 3763 }
 3764 
 3765 static struct knlist fs_knlist;
 3766 
 3767 static void
 3768 vfs_event_init(void *arg)
 3769 {
 3770         knlist_init(&fs_knlist, NULL, NULL, NULL, NULL);
 3771 }
 3772 /* XXX - correct order? */
 3773 SYSINIT(vfs_knlist, SI_SUB_VFS, SI_ORDER_ANY, vfs_event_init, NULL);
 3774 
 3775 void
 3776 vfs_event_signal(fsid_t *fsid, u_int32_t event, intptr_t data __unused)
 3777 {
 3778 
 3779         KNOTE_UNLOCKED(&fs_knlist, event);
 3780 }
 3781 
 3782 static int      filt_fsattach(struct knote *kn);
 3783 static void     filt_fsdetach(struct knote *kn);
 3784 static int      filt_fsevent(struct knote *kn, long hint);
 3785 
 3786 struct filterops fs_filtops =
 3787         { 0, filt_fsattach, filt_fsdetach, filt_fsevent };
 3788 
 3789 static int
 3790 filt_fsattach(struct knote *kn)
 3791 {
 3792 
 3793         kn->kn_flags |= EV_CLEAR;
 3794         knlist_add(&fs_knlist, kn, 0);
 3795         return (0);
 3796 }
 3797 
 3798 static void
 3799 filt_fsdetach(struct knote *kn)
 3800 {
 3801 
 3802         knlist_remove(&fs_knlist, kn, 0);
 3803 }
 3804 
 3805 static int
 3806 filt_fsevent(struct knote *kn, long hint)
 3807 {
 3808 
 3809         kn->kn_fflags |= hint;
 3810         return (kn->kn_fflags != 0);
 3811 }
 3812 
 3813 static int
 3814 sysctl_vfs_ctl(SYSCTL_HANDLER_ARGS)
 3815 {
 3816         struct vfsidctl vc;
 3817         int error;
 3818         struct mount *mp;
 3819 
 3820         error = SYSCTL_IN(req, &vc, sizeof(vc));
 3821         if (error)
 3822                 return (error);
 3823         if (vc.vc_vers != VFS_CTL_VERS1)
 3824                 return (EINVAL);
 3825         mp = vfs_getvfs(&vc.vc_fsid);
 3826         if (mp == NULL)
 3827                 return (ENOENT);
 3828         /* ensure that a specific sysctl goes to the right filesystem. */
 3829         if (strcmp(vc.vc_fstypename, "*") != 0 &&
 3830             strcmp(vc.vc_fstypename, mp->mnt_vfc->vfc_name) != 0) {
 3831                 vfs_rel(mp);
 3832                 return (EINVAL);
 3833         }
 3834         VCTLTOREQ(&vc, req);
 3835         error = VFS_SYSCTL(mp, vc.vc_op, req);
 3836         vfs_rel(mp);
 3837         return (error);
 3838 }
 3839 
 3840 SYSCTL_PROC(_vfs, OID_AUTO, ctl, CTLFLAG_WR, NULL, 0, sysctl_vfs_ctl, "",
 3841     "Sysctl by fsid");
 3842 
 3843 /*
 3844  * Function to initialize a va_filerev field sensibly.
 3845  * XXX: Wouldn't a random number make a lot more sense ??
 3846  */
 3847 u_quad_t
 3848 init_va_filerev(void)
 3849 {
 3850         struct bintime bt;
 3851 
 3852         getbinuptime(&bt);
 3853         return (((u_quad_t)bt.sec << 32LL) | (bt.frac >> 32LL));
 3854 }
 3855 
 3856 static int      filt_vfsread(struct knote *kn, long hint);
 3857 static int      filt_vfswrite(struct knote *kn, long hint);
 3858 static int      filt_vfsvnode(struct knote *kn, long hint);
 3859 static void     filt_vfsdetach(struct knote *kn);
 3860 static struct filterops vfsread_filtops =
 3861         { 1, NULL, filt_vfsdetach, filt_vfsread };
 3862 static struct filterops vfswrite_filtops =
 3863         { 1, NULL, filt_vfsdetach, filt_vfswrite };
 3864 static struct filterops vfsvnode_filtops =
 3865         { 1, NULL, filt_vfsdetach, filt_vfsvnode };
 3866 
 3867 static void
 3868 vfs_knllock(void *arg)
 3869 {
 3870         struct vnode *vp = arg;
 3871 
 3872         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, curthread);
 3873 }
 3874 
 3875 static void
 3876 vfs_knlunlock(void *arg)
 3877 {
 3878         struct vnode *vp = arg;
 3879 
 3880         VOP_UNLOCK(vp, 0, curthread);
 3881 }
 3882 
 3883 static int
 3884 vfs_knllocked(void *arg)
 3885 {
 3886         struct vnode *vp = arg;
 3887 
 3888         return (VOP_ISLOCKED(vp, curthread) == LK_EXCLUSIVE);
 3889 }
 3890 
 3891 int
 3892 vfs_kqfilter(struct vop_kqfilter_args *ap)
 3893 {
 3894         struct vnode *vp = ap->a_vp;
 3895         struct knote *kn = ap->a_kn;
 3896         struct knlist *knl;
 3897 
 3898         switch (kn->kn_filter) {
 3899         case EVFILT_READ:
 3900                 kn->kn_fop = &vfsread_filtops;
 3901                 break;
 3902         case EVFILT_WRITE:
 3903                 kn->kn_fop = &vfswrite_filtops;
 3904                 break;
 3905         case EVFILT_VNODE:
 3906                 kn->kn_fop = &vfsvnode_filtops;
 3907                 break;
 3908         default:
 3909                 return (EINVAL);
 3910         }
 3911 
 3912         kn->kn_hook = (caddr_t)vp;
 3913 
 3914         if (vp->v_pollinfo == NULL)
 3915                 v_addpollinfo(vp);
 3916         if (vp->v_pollinfo == NULL)
 3917                 return (ENOMEM);
 3918         knl = &vp->v_pollinfo->vpi_selinfo.si_note;
 3919         knlist_add(knl, kn, 0);
 3920 
 3921         return (0);
 3922 }
 3923 
 3924 /*
 3925  * Detach knote from vnode
 3926  */
 3927 static void
 3928 filt_vfsdetach(struct knote *kn)
 3929 {
 3930         struct vnode *vp = (struct vnode *)kn->kn_hook;
 3931 
 3932         KASSERT(vp->v_pollinfo != NULL, ("Missing v_pollinfo"));
 3933         knlist_remove(&vp->v_pollinfo->vpi_selinfo.si_note, kn, 0);
 3934 }
 3935 
 3936 /*ARGSUSED*/
 3937 static int
 3938 filt_vfsread(struct knote *kn, long hint)
 3939 {
 3940         struct vnode *vp = (struct vnode *)kn->kn_hook;
 3941         struct vattr va;
 3942 
 3943         /*
 3944          * filesystem is gone, so set the EOF flag and schedule
 3945          * the knote for deletion.
 3946          */
 3947         if (hint == NOTE_REVOKE) {
 3948                 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 3949                 return (1);
 3950         }
 3951 
 3952         if (VOP_GETATTR(vp, &va, curthread->td_ucred, curthread))
 3953                 return (0);
 3954 
 3955         kn->kn_data = va.va_size - kn->kn_fp->f_offset;
 3956         return (kn->kn_data != 0);
 3957 }
 3958 
 3959 /*ARGSUSED*/
 3960 static int
 3961 filt_vfswrite(struct knote *kn, long hint)
 3962 {
 3963         /*
 3964          * filesystem is gone, so set the EOF flag and schedule
 3965          * the knote for deletion.
 3966          */
 3967         if (hint == NOTE_REVOKE)
 3968                 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 3969 
 3970         kn->kn_data = 0;
 3971         return (1);
 3972 }
 3973 
 3974 static int
 3975 filt_vfsvnode(struct knote *kn, long hint)
 3976 {
 3977         if (kn->kn_sfflags & hint)
 3978                 kn->kn_fflags |= hint;
 3979         if (hint == NOTE_REVOKE) {
 3980                 kn->kn_flags |= EV_EOF;
 3981                 return (1);
 3982         }
 3983         return (kn->kn_fflags != 0);
 3984 }
 3985 
 3986 int
 3987 vfs_read_dirent(struct vop_readdir_args *ap, struct dirent *dp, off_t off)
 3988 {
 3989         int error;
 3990 
 3991         if (dp->d_reclen > ap->a_uio->uio_resid)
 3992                 return (ENAMETOOLONG);
 3993         error = uiomove(dp, dp->d_reclen, ap->a_uio);
 3994         if (error) {
 3995                 if (ap->a_ncookies != NULL) {
 3996                         if (ap->a_cookies != NULL)
 3997                                 free(ap->a_cookies, M_TEMP);
 3998                         ap->a_cookies = NULL;
 3999                         *ap->a_ncookies = 0;
 4000                 }
 4001                 return (error);
 4002         }
 4003         if (ap->a_ncookies == NULL)
 4004                 return (0);
 4005 
 4006         KASSERT(ap->a_cookies,
 4007             ("NULL ap->a_cookies value with non-NULL ap->a_ncookies!"));
 4008 
 4009         *ap->a_cookies = realloc(*ap->a_cookies,
 4010             (*ap->a_ncookies + 1) * sizeof(u_long), M_TEMP, M_WAITOK | M_ZERO);
 4011         (*ap->a_cookies)[*ap->a_ncookies] = off;
 4012         return (0);
 4013 }
 4014 
 4015 /*
 4016  * Mark for update the access time of the file if the filesystem
 4017  * supports VA_MARK_ATIME.  This functionality is used by execve
 4018  * and mmap, so we want to avoid the synchronous I/O implied by
 4019  * directly setting va_atime for the sake of efficiency.
 4020  */
 4021 void
 4022 vfs_mark_atime(struct vnode *vp, struct thread *td)
 4023 {
 4024         struct vattr atimeattr;
 4025 
 4026         if ((vp->v_mount->mnt_flag & (MNT_NOATIME | MNT_RDONLY)) == 0) {
 4027                 VATTR_NULL(&atimeattr);
 4028                 atimeattr.va_vaflags |= VA_MARK_ATIME;
 4029                 (void)VOP_SETATTR(vp, &atimeattr, td->td_ucred, td);
 4030         }
 4031 }

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