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/lockf.h>
   63 #include <sys/malloc.h>
   64 #include <sys/mount.h>
   65 #include <sys/namei.h>
   66 #include <sys/priv.h>
   67 #include <sys/reboot.h>
   68 #include <sys/sleepqueue.h>
   69 #include <sys/stat.h>
   70 #include <sys/sysctl.h>
   71 #include <sys/syslog.h>
   72 #include <sys/vmmeter.h>
   73 #include <sys/vnode.h>
   74 
   75 #include <machine/stdarg.h>
   76 
   77 #include <security/mac/mac_framework.h>
   78 
   79 #include <vm/vm.h>
   80 #include <vm/vm_object.h>
   81 #include <vm/vm_extern.h>
   82 #include <vm/pmap.h>
   83 #include <vm/vm_map.h>
   84 #include <vm/vm_page.h>
   85 #include <vm/vm_kern.h>
   86 #include <vm/uma.h>
   87 
   88 #ifdef DDB
   89 #include <ddb/ddb.h>
   90 #endif
   91 
   92 static MALLOC_DEFINE(M_NETADDR, "subr_export_host", "Export host address structure");
   93 
   94 static void     delmntque(struct vnode *vp);
   95 static int      flushbuflist(struct bufv *bufv, int flags, struct bufobj *bo,
   96                     int slpflag, int slptimeo);
   97 static void     syncer_shutdown(void *arg, int howto);
   98 static int      vtryrecycle(struct vnode *vp);
   99 static void     vbusy(struct vnode *vp);
  100 static void     vinactive(struct vnode *, struct thread *);
  101 static void     v_incr_usecount(struct vnode *);
  102 static void     v_decr_usecount(struct vnode *);
  103 static void     v_decr_useonly(struct vnode *);
  104 static void     v_upgrade_usecount(struct vnode *);
  105 static void     vfree(struct vnode *);
  106 static void     vnlru_free(int);
  107 static void     vdestroy(struct vnode *);
  108 static void     vgonel(struct vnode *);
  109 static void     vfs_knllock(void *arg);
  110 static void     vfs_knlunlock(void *arg);
  111 static int      vfs_knllocked(void *arg);
  112 static void     destroy_vpollinfo(struct vpollinfo *vi);
  113 
  114 /*
  115  * Enable Giant pushdown based on whether or not the vm is mpsafe in this
  116  * build.  Without mpsafevm the buffer cache can not run Giant free.
  117  */
  118 int mpsafe_vfs = 1;
  119 TUNABLE_INT("debug.mpsafevfs", &mpsafe_vfs);
  120 SYSCTL_INT(_debug, OID_AUTO, mpsafevfs, CTLFLAG_RD, &mpsafe_vfs, 0,
  121     "MPSAFE VFS");
  122 
  123 /*
  124  * Number of vnodes in existence.  Increased whenever getnewvnode()
  125  * allocates a new vnode, decreased on vdestroy() called on VI_DOOMed
  126  * vnode.
  127  */
  128 static unsigned long    numvnodes;
  129 
  130 SYSCTL_LONG(_vfs, OID_AUTO, numvnodes, CTLFLAG_RD, &numvnodes, 0, "");
  131 
  132 /*
  133  * Conversion tables for conversion from vnode types to inode formats
  134  * and back.
  135  */
  136 enum vtype iftovt_tab[16] = {
  137         VNON, VFIFO, VCHR, VNON, VDIR, VNON, VBLK, VNON,
  138         VREG, VNON, VLNK, VNON, VSOCK, VNON, VNON, VBAD,
  139 };
  140 int vttoif_tab[10] = {
  141         0, S_IFREG, S_IFDIR, S_IFBLK, S_IFCHR, S_IFLNK,
  142         S_IFSOCK, S_IFIFO, S_IFMT, S_IFMT
  143 };
  144 
  145 /*
  146  * List of vnodes that are ready for recycling.
  147  */
  148 static TAILQ_HEAD(freelst, vnode) vnode_free_list;
  149 
  150 /*
  151  * Free vnode target.  Free vnodes may simply be files which have been stat'd
  152  * but not read.  This is somewhat common, and a small cache of such files
  153  * should be kept to avoid recreation costs.
  154  */
  155 static u_long wantfreevnodes;
  156 SYSCTL_LONG(_vfs, OID_AUTO, wantfreevnodes, CTLFLAG_RW, &wantfreevnodes, 0, "");
  157 /* Number of vnodes in the free list. */
  158 static u_long freevnodes;
  159 SYSCTL_LONG(_vfs, OID_AUTO, freevnodes, CTLFLAG_RD, &freevnodes, 0, "");
  160 
  161 /*
  162  * Various variables used for debugging the new implementation of
  163  * reassignbuf().
  164  * XXX these are probably of (very) limited utility now.
  165  */
  166 static int reassignbufcalls;
  167 SYSCTL_INT(_vfs, OID_AUTO, reassignbufcalls, CTLFLAG_RW, &reassignbufcalls, 0, "");
  168 
  169 /*
  170  * Cache for the mount type id assigned to NFS.  This is used for
  171  * special checks in nfs/nfs_nqlease.c and vm/vnode_pager.c.
  172  */
  173 int     nfs_mount_type = -1;
  174 
  175 /* To keep more than one thread at a time from running vfs_getnewfsid */
  176 static struct mtx mntid_mtx;
  177 
  178 /*
  179  * Lock for any access to the following:
  180  *      vnode_free_list
  181  *      numvnodes
  182  *      freevnodes
  183  */
  184 static struct mtx vnode_free_list_mtx;
  185 
  186 /* Publicly exported FS */
  187 struct nfs_public nfs_pub;
  188 
  189 /* Zone for allocation of new vnodes - used exclusively by getnewvnode() */
  190 static uma_zone_t vnode_zone;
  191 static uma_zone_t vnodepoll_zone;
  192 
  193 /* Set to 1 to print out reclaim of active vnodes */
  194 int     prtactive;
  195 
  196 /*
  197  * The workitem queue.
  198  *
  199  * It is useful to delay writes of file data and filesystem metadata
  200  * for tens of seconds so that quickly created and deleted files need
  201  * not waste disk bandwidth being created and removed. To realize this,
  202  * we append vnodes to a "workitem" queue. When running with a soft
  203  * updates implementation, most pending metadata dependencies should
  204  * not wait for more than a few seconds. Thus, mounted on block devices
  205  * are delayed only about a half the time that file data is delayed.
  206  * Similarly, directory updates are more critical, so are only delayed
  207  * about a third the time that file data is delayed. Thus, there are
  208  * SYNCER_MAXDELAY queues that are processed round-robin at a rate of
  209  * one each second (driven off the filesystem syncer process). The
  210  * syncer_delayno variable indicates the next queue that is to be processed.
  211  * Items that need to be processed soon are placed in this queue:
  212  *
  213  *      syncer_workitem_pending[syncer_delayno]
  214  *
  215  * A delay of fifteen seconds is done by placing the request fifteen
  216  * entries later in the queue:
  217  *
  218  *      syncer_workitem_pending[(syncer_delayno + 15) & syncer_mask]
  219  *
  220  */
  221 static int syncer_delayno;
  222 static long syncer_mask;
  223 LIST_HEAD(synclist, bufobj);
  224 static struct synclist *syncer_workitem_pending;
  225 /*
  226  * The sync_mtx protects:
  227  *      bo->bo_synclist
  228  *      sync_vnode_count
  229  *      syncer_delayno
  230  *      syncer_state
  231  *      syncer_workitem_pending
  232  *      syncer_worklist_len
  233  *      rushjob
  234  */
  235 static struct mtx sync_mtx;
  236 
  237 #define SYNCER_MAXDELAY         32
  238 static int syncer_maxdelay = SYNCER_MAXDELAY;   /* maximum delay time */
  239 static int syncdelay = 30;              /* max time to delay syncing data */
  240 static int filedelay = 30;              /* time to delay syncing files */
  241 SYSCTL_INT(_kern, OID_AUTO, filedelay, CTLFLAG_RW, &filedelay, 0, "");
  242 static int dirdelay = 29;               /* time to delay syncing directories */
  243 SYSCTL_INT(_kern, OID_AUTO, dirdelay, CTLFLAG_RW, &dirdelay, 0, "");
  244 static int metadelay = 28;              /* time to delay syncing metadata */
  245 SYSCTL_INT(_kern, OID_AUTO, metadelay, CTLFLAG_RW, &metadelay, 0, "");
  246 static int rushjob;             /* number of slots to run ASAP */
  247 static int stat_rush_requests;  /* number of times I/O speeded up */
  248 SYSCTL_INT(_debug, OID_AUTO, rush_requests, CTLFLAG_RW, &stat_rush_requests, 0, "");
  249 
  250 /*
  251  * When shutting down the syncer, run it at four times normal speed.
  252  */
  253 #define SYNCER_SHUTDOWN_SPEEDUP         4
  254 static int sync_vnode_count;
  255 static int syncer_worklist_len;
  256 static enum { SYNCER_RUNNING, SYNCER_SHUTTING_DOWN, SYNCER_FINAL_DELAY }
  257     syncer_state;
  258 
  259 /*
  260  * Number of vnodes we want to exist at any one time.  This is mostly used
  261  * to size hash tables in vnode-related code.  It is normally not used in
  262  * getnewvnode(), as wantfreevnodes is normally nonzero.)
  263  *
  264  * XXX desiredvnodes is historical cruft and should not exist.
  265  */
  266 int desiredvnodes;
  267 SYSCTL_INT(_kern, KERN_MAXVNODES, maxvnodes, CTLFLAG_RW,
  268     &desiredvnodes, 0, "Maximum number of vnodes");
  269 SYSCTL_INT(_kern, OID_AUTO, minvnodes, CTLFLAG_RW,
  270     &wantfreevnodes, 0, "Minimum number of vnodes (legacy)");
  271 static int vnlru_nowhere;
  272 SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RW,
  273     &vnlru_nowhere, 0, "Number of times the vnlru process ran without success");
  274 
  275 /*
  276  * Macros to control when a vnode is freed and recycled.  All require
  277  * the vnode interlock.
  278  */
  279 #define VCANRECYCLE(vp) (((vp)->v_iflag & VI_FREE) && !(vp)->v_holdcnt)
  280 #define VSHOULDFREE(vp) (!((vp)->v_iflag & VI_FREE) && !(vp)->v_holdcnt)
  281 #define VSHOULDBUSY(vp) (((vp)->v_iflag & VI_FREE) && (vp)->v_holdcnt)
  282 
  283 
  284 /*
  285  * Initialize the vnode management data structures.
  286  */
  287 #ifndef MAXVNODES_MAX
  288 #define MAXVNODES_MAX   100000
  289 #endif
  290 static void
  291 vntblinit(void *dummy __unused)
  292 {
  293 
  294         /*
  295          * Desiredvnodes is a function of the physical memory size and
  296          * the kernel's heap size.  Specifically, desiredvnodes scales
  297          * in proportion to the physical memory size until two fifths
  298          * of the kernel's heap size is consumed by vnodes and vm
  299          * objects.
  300          */
  301         desiredvnodes = min(maxproc + cnt.v_page_count / 4, 2 * vm_kmem_size /
  302             (5 * (sizeof(struct vm_object) + sizeof(struct vnode))));
  303         if (desiredvnodes > MAXVNODES_MAX) {
  304                 if (bootverbose)
  305                         printf("Reducing kern.maxvnodes %d -> %d\n",
  306                             desiredvnodes, MAXVNODES_MAX);
  307                 desiredvnodes = MAXVNODES_MAX;
  308         }
  309         wantfreevnodes = desiredvnodes / 4;
  310         mtx_init(&mntid_mtx, "mntid", NULL, MTX_DEF);
  311         TAILQ_INIT(&vnode_free_list);
  312         mtx_init(&vnode_free_list_mtx, "vnode_free_list", NULL, MTX_DEF);
  313         vnode_zone = uma_zcreate("VNODE", sizeof (struct vnode), NULL, NULL,
  314             NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  315         vnodepoll_zone = uma_zcreate("VNODEPOLL", sizeof (struct vpollinfo),
  316             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  317         /*
  318          * Initialize the filesystem syncer.
  319          */
  320         syncer_workitem_pending = hashinit(syncer_maxdelay, M_VNODE,
  321                 &syncer_mask);
  322         syncer_maxdelay = syncer_mask + 1;
  323         mtx_init(&sync_mtx, "Syncer mtx", NULL, MTX_DEF);
  324 }
  325 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_FIRST, vntblinit, NULL);
  326 
  327 
  328 /*
  329  * Mark a mount point as busy. Used to synchronize access and to delay
  330  * unmounting. Interlock is not released on failure.
  331  */
  332 int
  333 vfs_busy(struct mount *mp, int flags, struct mtx *interlkp,
  334     struct thread *td)
  335 {
  336         int lkflags;
  337 
  338         MNT_ILOCK(mp);
  339         MNT_REF(mp);
  340         if (mp->mnt_kern_flag & MNTK_UNMOUNT) {
  341                 if (flags & LK_NOWAIT) {
  342                         MNT_REL(mp);
  343                         MNT_IUNLOCK(mp);
  344                         return (ENOENT);
  345                 }
  346                 if (interlkp)
  347                         mtx_unlock(interlkp);
  348                 mp->mnt_kern_flag |= MNTK_MWAIT;
  349                 /*
  350                  * Since all busy locks are shared except the exclusive
  351                  * lock granted when unmounting, the only place that a
  352                  * wakeup needs to be done is at the release of the
  353                  * exclusive lock at the end of dounmount.
  354                  */
  355                 msleep(mp, MNT_MTX(mp), PVFS, "vfs_busy", 0);
  356                 MNT_REL(mp);
  357                 MNT_IUNLOCK(mp);
  358                 if (interlkp)
  359                         mtx_lock(interlkp);
  360                 return (ENOENT);
  361         }
  362         if (interlkp)
  363                 mtx_unlock(interlkp);
  364         lkflags = LK_SHARED | LK_INTERLOCK | LK_NOWAIT;
  365         if (lockmgr(&mp->mnt_lock, lkflags, MNT_MTX(mp), td))
  366                 panic("vfs_busy: unexpected lock failure");
  367         return (0);
  368 }
  369 
  370 /*
  371  * Free a busy filesystem.
  372  */
  373 void
  374 vfs_unbusy(struct mount *mp, struct thread *td)
  375 {
  376 
  377         lockmgr(&mp->mnt_lock, LK_RELEASE, NULL, td);
  378         vfs_rel(mp);
  379 }
  380 
  381 /*
  382  * Lookup a mount point by filesystem identifier.
  383  */
  384 struct mount *
  385 vfs_getvfs(fsid_t *fsid)
  386 {
  387         struct mount *mp;
  388 
  389         mtx_lock(&mountlist_mtx);
  390         TAILQ_FOREACH(mp, &mountlist, mnt_list) {
  391                 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
  392                     mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
  393                         vfs_ref(mp);
  394                         mtx_unlock(&mountlist_mtx);
  395                         return (mp);
  396                 }
  397         }
  398         mtx_unlock(&mountlist_mtx);
  399         return ((struct mount *) 0);
  400 }
  401 
  402 /*
  403  * Check if a user can access privileged mount options.
  404  */
  405 int
  406 vfs_suser(struct mount *mp, struct thread *td)
  407 {
  408         int error;
  409 
  410         /*
  411          * If the thread is jailed, but this is not a jail-friendly file
  412          * system, deny immediately.
  413          */
  414         if (jailed(td->td_ucred) && !(mp->mnt_vfc->vfc_flags & VFCF_JAIL))
  415                 return (EPERM);
  416 
  417         /*
  418          * If the file system was mounted outside a jail and a jailed thread
  419          * tries to access it, deny immediately.
  420          */
  421         if (!jailed(mp->mnt_cred) && jailed(td->td_ucred))
  422                 return (EPERM);
  423 
  424         /*
  425          * If the file system was mounted inside different jail that the jail of
  426          * the calling thread, deny immediately.
  427          */
  428         if (jailed(mp->mnt_cred) && jailed(td->td_ucred) &&
  429             mp->mnt_cred->cr_prison != td->td_ucred->cr_prison) {
  430                 return (EPERM);
  431         }
  432 
  433         if ((mp->mnt_flag & MNT_USER) == 0 ||
  434             mp->mnt_cred->cr_uid != td->td_ucred->cr_uid) {
  435                 if ((error = priv_check(td, PRIV_VFS_MOUNT_OWNER)) != 0)
  436                         return (error);
  437         }
  438         return (0);
  439 }
  440 
  441 /*
  442  * Get a new unique fsid.  Try to make its val[0] unique, since this value
  443  * will be used to create fake device numbers for stat().  Also try (but
  444  * not so hard) make its val[0] unique mod 2^16, since some emulators only
  445  * support 16-bit device numbers.  We end up with unique val[0]'s for the
  446  * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls.
  447  *
  448  * Keep in mind that several mounts may be running in parallel.  Starting
  449  * the search one past where the previous search terminated is both a
  450  * micro-optimization and a defense against returning the same fsid to
  451  * different mounts.
  452  */
  453 void
  454 vfs_getnewfsid(struct mount *mp)
  455 {
  456         static u_int16_t mntid_base;
  457         struct mount *nmp;
  458         fsid_t tfsid;
  459         int mtype;
  460 
  461         mtx_lock(&mntid_mtx);
  462         mtype = mp->mnt_vfc->vfc_typenum;
  463         tfsid.val[1] = mtype;
  464         mtype = (mtype & 0xFF) << 24;
  465         for (;;) {
  466                 tfsid.val[0] = makedev(255,
  467                     mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF));
  468                 mntid_base++;
  469                 if ((nmp = vfs_getvfs(&tfsid)) == NULL)
  470                         break;
  471                 vfs_rel(nmp);
  472         }
  473         mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
  474         mp->mnt_stat.f_fsid.val[1] = tfsid.val[1];
  475         mtx_unlock(&mntid_mtx);
  476 }
  477 
  478 /*
  479  * Knob to control the precision of file timestamps:
  480  *
  481  *   0 = seconds only; nanoseconds zeroed.
  482  *   1 = seconds and nanoseconds, accurate within 1/HZ.
  483  *   2 = seconds and nanoseconds, truncated to microseconds.
  484  * >=3 = seconds and nanoseconds, maximum precision.
  485  */
  486 enum { TSP_SEC, TSP_HZ, TSP_USEC, TSP_NSEC };
  487 
  488 static int timestamp_precision = TSP_SEC;
  489 SYSCTL_INT(_vfs, OID_AUTO, timestamp_precision, CTLFLAG_RW,
  490     &timestamp_precision, 0, "");
  491 
  492 /*
  493  * Get a current timestamp.
  494  */
  495 void
  496 vfs_timestamp(struct timespec *tsp)
  497 {
  498         struct timeval tv;
  499 
  500         switch (timestamp_precision) {
  501         case TSP_SEC:
  502                 tsp->tv_sec = time_second;
  503                 tsp->tv_nsec = 0;
  504                 break;
  505         case TSP_HZ:
  506                 getnanotime(tsp);
  507                 break;
  508         case TSP_USEC:
  509                 microtime(&tv);
  510                 TIMEVAL_TO_TIMESPEC(&tv, tsp);
  511                 break;
  512         case TSP_NSEC:
  513         default:
  514                 nanotime(tsp);
  515                 break;
  516         }
  517 }
  518 
  519 /*
  520  * Set vnode attributes to VNOVAL
  521  */
  522 void
  523 vattr_null(struct vattr *vap)
  524 {
  525 
  526         vap->va_type = VNON;
  527         vap->va_size = VNOVAL;
  528         vap->va_bytes = VNOVAL;
  529         vap->va_mode = VNOVAL;
  530         vap->va_nlink = VNOVAL;
  531         vap->va_uid = VNOVAL;
  532         vap->va_gid = VNOVAL;
  533         vap->va_fsid = VNOVAL;
  534         vap->va_fileid = VNOVAL;
  535         vap->va_blocksize = VNOVAL;
  536         vap->va_rdev = VNOVAL;
  537         vap->va_atime.tv_sec = VNOVAL;
  538         vap->va_atime.tv_nsec = VNOVAL;
  539         vap->va_mtime.tv_sec = VNOVAL;
  540         vap->va_mtime.tv_nsec = VNOVAL;
  541         vap->va_ctime.tv_sec = VNOVAL;
  542         vap->va_ctime.tv_nsec = VNOVAL;
  543         vap->va_birthtime.tv_sec = VNOVAL;
  544         vap->va_birthtime.tv_nsec = VNOVAL;
  545         vap->va_flags = VNOVAL;
  546         vap->va_gen = VNOVAL;
  547         vap->va_vaflags = 0;
  548 }
  549 
  550 /*
  551  * This routine is called when we have too many vnodes.  It attempts
  552  * to free <count> vnodes and will potentially free vnodes that still
  553  * have VM backing store (VM backing store is typically the cause
  554  * of a vnode blowout so we want to do this).  Therefore, this operation
  555  * is not considered cheap.
  556  *
  557  * A number of conditions may prevent a vnode from being reclaimed.
  558  * the buffer cache may have references on the vnode, a directory
  559  * vnode may still have references due to the namei cache representing
  560  * underlying files, or the vnode may be in active use.   It is not
  561  * desireable to reuse such vnodes.  These conditions may cause the
  562  * number of vnodes to reach some minimum value regardless of what
  563  * you set kern.maxvnodes to.  Do not set kern.maxvnodes too low.
  564  */
  565 static int
  566 vlrureclaim(struct mount *mp)
  567 {
  568         struct thread *td;
  569         struct vnode *vp;
  570         int done;
  571         int trigger;
  572         int usevnodes;
  573         int count;
  574 
  575         /*
  576          * Calculate the trigger point, don't allow user
  577          * screwups to blow us up.   This prevents us from
  578          * recycling vnodes with lots of resident pages.  We
  579          * aren't trying to free memory, we are trying to
  580          * free vnodes.
  581          */
  582         usevnodes = desiredvnodes;
  583         if (usevnodes <= 0)
  584                 usevnodes = 1;
  585         trigger = cnt.v_page_count * 2 / usevnodes;
  586         done = 0;
  587         td = curthread;
  588         vn_start_write(NULL, &mp, V_WAIT);
  589         MNT_ILOCK(mp);
  590         count = mp->mnt_nvnodelistsize / 10 + 1;
  591         while (count != 0) {
  592                 vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
  593                 while (vp != NULL && vp->v_type == VMARKER)
  594                         vp = TAILQ_NEXT(vp, v_nmntvnodes);
  595                 if (vp == NULL)
  596                         break;
  597                 TAILQ_REMOVE(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
  598                 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
  599                 --count;
  600                 if (!VI_TRYLOCK(vp))
  601                         goto next_iter;
  602                 /*
  603                  * If it's been deconstructed already, it's still
  604                  * referenced, or it exceeds the trigger, skip it.
  605                  */
  606                 if (vp->v_usecount || !LIST_EMPTY(&(vp)->v_cache_src) ||
  607                     (vp->v_iflag & VI_DOOMED) != 0 || (vp->v_object != NULL &&
  608                     vp->v_object->resident_page_count > trigger)) {
  609                         VI_UNLOCK(vp);
  610                         goto next_iter;
  611                 }
  612                 MNT_IUNLOCK(mp);
  613                 vholdl(vp);
  614                 if (VOP_LOCK(vp, LK_INTERLOCK|LK_EXCLUSIVE|LK_NOWAIT, td)) {
  615                         vdrop(vp);
  616                         goto next_iter_mntunlocked;
  617                 }
  618                 VI_LOCK(vp);
  619                 /*
  620                  * v_usecount may have been bumped after VOP_LOCK() dropped
  621                  * the vnode interlock and before it was locked again.
  622                  *
  623                  * It is not necessary to recheck VI_DOOMED because it can
  624                  * only be set by another thread that holds both the vnode
  625                  * lock and vnode interlock.  If another thread has the
  626                  * vnode lock before we get to VOP_LOCK() and obtains the
  627                  * vnode interlock after VOP_LOCK() drops the vnode
  628                  * interlock, the other thread will be unable to drop the
  629                  * vnode lock before our VOP_LOCK() call fails.
  630                  */
  631                 if (vp->v_usecount || !LIST_EMPTY(&(vp)->v_cache_src) ||
  632                     (vp->v_object != NULL &&
  633                     vp->v_object->resident_page_count > trigger)) {
  634                         VOP_UNLOCK(vp, LK_INTERLOCK, td);
  635                         goto next_iter_mntunlocked;
  636                 }
  637                 KASSERT((vp->v_iflag & VI_DOOMED) == 0,
  638                     ("VI_DOOMED unexpectedly detected in vlrureclaim()"));
  639                 vgonel(vp);
  640                 VOP_UNLOCK(vp, 0, td);
  641                 vdropl(vp);
  642                 done++;
  643 next_iter_mntunlocked:
  644                 if ((count % 256) != 0)
  645                         goto relock_mnt;
  646                 goto yield;
  647 next_iter:
  648                 if ((count % 256) != 0)
  649                         continue;
  650                 MNT_IUNLOCK(mp);
  651 yield:
  652                 uio_yield();
  653 relock_mnt:
  654                 MNT_ILOCK(mp);
  655         }
  656         MNT_IUNLOCK(mp);
  657         vn_finished_write(mp);
  658         return done;
  659 }
  660 
  661 /*
  662  * Attempt to keep the free list at wantfreevnodes length.
  663  */
  664 static void
  665 vnlru_free(int count)
  666 {
  667         struct vnode *vp;
  668         int vfslocked;
  669 
  670         mtx_assert(&vnode_free_list_mtx, MA_OWNED);
  671         for (; count > 0; count--) {
  672                 vp = TAILQ_FIRST(&vnode_free_list);
  673                 /*
  674                  * The list can be modified while the free_list_mtx
  675                  * has been dropped and vp could be NULL here.
  676                  */
  677                 if (!vp)
  678                         break;
  679                 VNASSERT(vp->v_op != NULL, vp,
  680                     ("vnlru_free: vnode already reclaimed."));
  681                 TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
  682                 /*
  683                  * Don't recycle if we can't get the interlock.
  684                  */
  685                 if (!VI_TRYLOCK(vp)) {
  686                         TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
  687                         continue;
  688                 }
  689                 VNASSERT(VCANRECYCLE(vp), vp,
  690                     ("vp inconsistent on freelist"));
  691                 freevnodes--;
  692                 vp->v_iflag &= ~VI_FREE;
  693                 vholdl(vp);
  694                 mtx_unlock(&vnode_free_list_mtx);
  695                 VI_UNLOCK(vp);
  696                 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  697                 vtryrecycle(vp);
  698                 VFS_UNLOCK_GIANT(vfslocked);
  699                 /*
  700                  * If the recycled succeeded this vdrop will actually free
  701                  * the vnode.  If not it will simply place it back on
  702                  * the free list.
  703                  */
  704                 vdrop(vp);
  705                 mtx_lock(&vnode_free_list_mtx);
  706         }
  707 }
  708 /*
  709  * Attempt to recycle vnodes in a context that is always safe to block.
  710  * Calling vlrurecycle() from the bowels of filesystem code has some
  711  * interesting deadlock problems.
  712  */
  713 static struct proc *vnlruproc;
  714 static int vnlruproc_sig;
  715 
  716 static void
  717 vnlru_proc(void)
  718 {
  719         struct mount *mp, *nmp;
  720         int done;
  721         struct proc *p = vnlruproc;
  722         struct thread *td = curthread;
  723 
  724         EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, p,
  725             SHUTDOWN_PRI_FIRST);
  726 
  727         mtx_lock(&Giant);
  728 
  729         for (;;) {
  730                 kthread_suspend_check(p);
  731                 mtx_lock(&vnode_free_list_mtx);
  732                 if (freevnodes > wantfreevnodes)
  733                         vnlru_free(freevnodes - wantfreevnodes);
  734                 if (numvnodes <= desiredvnodes * 9 / 10) {
  735                         vnlruproc_sig = 0;
  736                         wakeup(&vnlruproc_sig);
  737                         msleep(vnlruproc, &vnode_free_list_mtx,
  738                             PVFS|PDROP, "vlruwt", hz);
  739                         continue;
  740                 }
  741                 mtx_unlock(&vnode_free_list_mtx);
  742                 done = 0;
  743                 mtx_lock(&mountlist_mtx);
  744                 for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
  745                         int vfsunlocked;
  746                         if (vfs_busy(mp, LK_NOWAIT, &mountlist_mtx, td)) {
  747                                 nmp = TAILQ_NEXT(mp, mnt_list);
  748                                 continue;
  749                         }
  750                         if (!VFS_NEEDSGIANT(mp)) {
  751                                 mtx_unlock(&Giant);
  752                                 vfsunlocked = 1;
  753                         } else
  754                                 vfsunlocked = 0;
  755                         done += vlrureclaim(mp);
  756                         if (vfsunlocked)
  757                                 mtx_lock(&Giant);
  758                         mtx_lock(&mountlist_mtx);
  759                         nmp = TAILQ_NEXT(mp, mnt_list);
  760                         vfs_unbusy(mp, td);
  761                 }
  762                 mtx_unlock(&mountlist_mtx);
  763                 if (done == 0) {
  764                         EVENTHANDLER_INVOKE(vfs_lowvnodes, desiredvnodes / 10);
  765 #if 0
  766                         /* These messages are temporary debugging aids */
  767                         if (vnlru_nowhere < 5)
  768                                 printf("vnlru process getting nowhere..\n");
  769                         else if (vnlru_nowhere == 5)
  770                                 printf("vnlru process messages stopped.\n");
  771 #endif
  772                         vnlru_nowhere++;
  773                         tsleep(vnlruproc, PPAUSE, "vlrup", hz * 3);
  774                 } else
  775                         uio_yield();
  776         }
  777 }
  778 
  779 static struct kproc_desc vnlru_kp = {
  780         "vnlru",
  781         vnlru_proc,
  782         &vnlruproc
  783 };
  784 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start,
  785     &vnlru_kp);
  786 
  787 /*
  788  * Routines having to do with the management of the vnode table.
  789  */
  790 
  791 static void
  792 vdestroy(struct vnode *vp)
  793 {
  794         struct bufobj *bo;
  795 
  796         CTR1(KTR_VFS, "vdestroy vp %p", vp);
  797         mtx_lock(&vnode_free_list_mtx);
  798         numvnodes--;
  799         mtx_unlock(&vnode_free_list_mtx);
  800         bo = &vp->v_bufobj;
  801         VNASSERT((vp->v_iflag & VI_FREE) == 0, vp,
  802             ("cleaned vnode still on the free list."));
  803         VNASSERT(vp->v_data == NULL, vp, ("cleaned vnode isn't"));
  804         VNASSERT(vp->v_holdcnt == 0, vp, ("Non-zero hold count"));
  805         VNASSERT(vp->v_usecount == 0, vp, ("Non-zero use count"));
  806         VNASSERT(vp->v_writecount == 0, vp, ("Non-zero write count"));
  807         VNASSERT(bo->bo_numoutput == 0, vp, ("Clean vnode has pending I/O's"));
  808         VNASSERT(bo->bo_clean.bv_cnt == 0, vp, ("cleanbufcnt not 0"));
  809         VNASSERT(bo->bo_clean.bv_root == NULL, vp, ("cleanblkroot not NULL"));
  810         VNASSERT(bo->bo_dirty.bv_cnt == 0, vp, ("dirtybufcnt not 0"));
  811         VNASSERT(bo->bo_dirty.bv_root == NULL, vp, ("dirtyblkroot not NULL"));
  812         VNASSERT(TAILQ_EMPTY(&vp->v_cache_dst), vp, ("vp has namecache dst"));
  813         VNASSERT(LIST_EMPTY(&vp->v_cache_src), vp, ("vp has namecache src"));
  814         VI_UNLOCK(vp);
  815 #ifdef MAC
  816         mac_destroy_vnode(vp);
  817 #endif
  818         if (vp->v_pollinfo != NULL)
  819                 destroy_vpollinfo(vp->v_pollinfo);
  820 #ifdef INVARIANTS
  821         /* XXX Elsewhere we can detect an already freed vnode via NULL v_op. */
  822         vp->v_op = NULL;
  823 #endif
  824         lockdestroy(vp->v_vnlock);
  825         mtx_destroy(&vp->v_interlock);
  826         uma_zfree(vnode_zone, vp);
  827 }
  828 
  829 /*
  830  * Try to recycle a freed vnode.  We abort if anyone picks up a reference
  831  * before we actually vgone().  This function must be called with the vnode
  832  * held to prevent the vnode from being returned to the free list midway
  833  * through vgone().
  834  */
  835 static int
  836 vtryrecycle(struct vnode *vp)
  837 {
  838         struct thread *td = curthread;
  839         struct mount *vnmp;
  840 
  841         CTR1(KTR_VFS, "vtryrecycle: trying vp %p", vp);
  842         VNASSERT(vp->v_holdcnt, vp,
  843             ("vtryrecycle: Recycling vp %p without a reference.", vp));
  844         /*
  845          * This vnode may found and locked via some other list, if so we
  846          * can't recycle it yet.
  847          */
  848         if (VOP_LOCK(vp, LK_EXCLUSIVE | LK_NOWAIT, td) != 0)
  849                 return (EWOULDBLOCK);
  850         /*
  851          * Don't recycle if its filesystem is being suspended.
  852          */
  853         if (vn_start_write(vp, &vnmp, V_NOWAIT) != 0) {
  854                 VOP_UNLOCK(vp, 0, td);
  855                 return (EBUSY);
  856         }
  857         /*
  858          * If we got this far, we need to acquire the interlock and see if
  859          * anyone picked up this vnode from another list.  If not, we will
  860          * mark it with DOOMED via vgonel() so that anyone who does find it
  861          * will skip over it.
  862          */
  863         VI_LOCK(vp);
  864         if (vp->v_usecount) {
  865                 VOP_UNLOCK(vp, LK_INTERLOCK, td);
  866                 vn_finished_write(vnmp);
  867                 return (EBUSY);
  868         }
  869         if ((vp->v_iflag & VI_DOOMED) == 0)
  870                 vgonel(vp);
  871         VOP_UNLOCK(vp, LK_INTERLOCK, td);
  872         vn_finished_write(vnmp);
  873         CTR1(KTR_VFS, "vtryrecycle: recycled vp %p", vp);
  874         return (0);
  875 }
  876 
  877 /*
  878  * Return the next vnode from the free list.
  879  */
  880 int
  881 getnewvnode(const char *tag, struct mount *mp, struct vop_vector *vops,
  882     struct vnode **vpp)
  883 {
  884         struct vnode *vp = NULL;
  885         struct bufobj *bo;
  886 
  887         mtx_lock(&vnode_free_list_mtx);
  888         /*
  889          * Lend our context to reclaim vnodes if they've exceeded the max.
  890          */
  891         if (freevnodes > wantfreevnodes)
  892                 vnlru_free(1);
  893         /*
  894          * Wait for available vnodes.
  895          */
  896         if (numvnodes > desiredvnodes) {
  897                 if (mp != NULL && (mp->mnt_kern_flag & MNTK_SUSPEND)) {
  898                         /*
  899                          * File system is beeing suspended, we cannot risk a
  900                          * deadlock here, so allocate new vnode anyway.
  901                          */
  902                         if (freevnodes > wantfreevnodes)
  903                                 vnlru_free(freevnodes - wantfreevnodes);
  904                         goto alloc;
  905                 }
  906                 if (vnlruproc_sig == 0) {
  907                         vnlruproc_sig = 1;      /* avoid unnecessary wakeups */
  908                         wakeup(vnlruproc);
  909                 }
  910                 msleep(&vnlruproc_sig, &vnode_free_list_mtx, PVFS,
  911                     "vlruwk", hz);
  912 #if 0   /* XXX Not all VFS_VGET/ffs_vget callers check returns. */
  913                 if (numvnodes > desiredvnodes) {
  914                         mtx_unlock(&vnode_free_list_mtx);
  915                         return (ENFILE);
  916                 }
  917 #endif
  918         }
  919 alloc:
  920         numvnodes++;
  921         mtx_unlock(&vnode_free_list_mtx);
  922         vp = (struct vnode *) uma_zalloc(vnode_zone, M_WAITOK|M_ZERO);
  923         /*
  924          * Setup locks.
  925          */
  926         vp->v_vnlock = &vp->v_lock;
  927         mtx_init(&vp->v_interlock, "vnode interlock", NULL, MTX_DEF);
  928         /*
  929          * By default, don't allow shared locks unless filesystems
  930          * opt-in.
  931          */
  932         lockinit(vp->v_vnlock, PVFS, tag, VLKTIMEOUT, LK_NOSHARE);
  933         /*
  934          * Initialize bufobj.
  935          */
  936         bo = &vp->v_bufobj;
  937         bo->__bo_vnode = vp;
  938         bo->bo_mtx = &vp->v_interlock;
  939         bo->bo_ops = &buf_ops_bio;
  940         bo->bo_private = vp;
  941         TAILQ_INIT(&bo->bo_clean.bv_hd);
  942         TAILQ_INIT(&bo->bo_dirty.bv_hd);
  943         /*
  944          * Initialize namecache.
  945          */
  946         LIST_INIT(&vp->v_cache_src);
  947         TAILQ_INIT(&vp->v_cache_dst);
  948         /*
  949          * Finalize various vnode identity bits.
  950          */
  951         vp->v_type = VNON;
  952         vp->v_tag = tag;
  953         vp->v_op = vops;
  954         v_incr_usecount(vp);
  955         vp->v_data = 0;
  956 #ifdef MAC
  957         mac_init_vnode(vp);
  958         if (mp != NULL && (mp->mnt_flag & MNT_MULTILABEL) == 0)
  959                 mac_associate_vnode_singlelabel(mp, vp);
  960         else if (mp == NULL)
  961                 printf("NULL mp in getnewvnode()\n");
  962 #endif
  963         if (mp != NULL) {
  964                 bo->bo_bsize = mp->mnt_stat.f_iosize;
  965                 if ((mp->mnt_kern_flag & MNTK_NOKNOTE) != 0)
  966                         vp->v_vflag |= VV_NOKNOTE;
  967         }
  968 
  969         CTR2(KTR_VFS, "getnewvnode: mp %p vp %p", mp, vp);
  970         *vpp = vp;
  971         return (0);
  972 }
  973 
  974 /*
  975  * Delete from old mount point vnode list, if on one.
  976  */
  977 static void
  978 delmntque(struct vnode *vp)
  979 {
  980         struct mount *mp;
  981 
  982         mp = vp->v_mount;
  983         if (mp == NULL)
  984                 return;
  985         MNT_ILOCK(mp);
  986         vp->v_mount = NULL;
  987         VNASSERT(mp->mnt_nvnodelistsize > 0, vp,
  988                 ("bad mount point vnode list size"));
  989         TAILQ_REMOVE(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
  990         mp->mnt_nvnodelistsize--;
  991         MNT_REL(mp);
  992         MNT_IUNLOCK(mp);
  993 }
  994 
  995 static void
  996 insmntque_stddtr(struct vnode *vp, void *dtr_arg)
  997 {
  998         struct thread *td;
  999 
 1000         td = curthread; /* XXX ? */
 1001         vp->v_data = NULL;
 1002         vp->v_op = &dead_vnodeops;
 1003         /* XXX non mp-safe fs may still call insmntque with vnode
 1004            unlocked */
 1005         if (!VOP_ISLOCKED(vp, td))
 1006                 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1007         vgone(vp);
 1008         vput(vp);
 1009 }
 1010 
 1011 /*
 1012  * Insert into list of vnodes for the new mount point, if available.
 1013  */
 1014 int
 1015 insmntque1(struct vnode *vp, struct mount *mp,
 1016         void (*dtr)(struct vnode *, void *), void *dtr_arg)
 1017 {
 1018 
 1019         KASSERT(vp->v_mount == NULL,
 1020                 ("insmntque: vnode already on per mount vnode list"));
 1021         VNASSERT(mp != NULL, vp, ("Don't call insmntque(foo, NULL)"));
 1022         MNT_ILOCK(mp);
 1023         if ((mp->mnt_kern_flag & MNTK_NOINSMNTQ) != 0 &&
 1024             mp->mnt_nvnodelistsize == 0) {
 1025                 MNT_IUNLOCK(mp);
 1026                 if (dtr != NULL)
 1027                         dtr(vp, dtr_arg);
 1028                 return (EBUSY);
 1029         }
 1030         vp->v_mount = mp;
 1031         MNT_REF(mp);
 1032         TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
 1033         VNASSERT(mp->mnt_nvnodelistsize >= 0, vp,
 1034                 ("neg mount point vnode list size"));
 1035         mp->mnt_nvnodelistsize++;
 1036         MNT_IUNLOCK(mp);
 1037         return (0);
 1038 }
 1039 
 1040 int
 1041 insmntque(struct vnode *vp, struct mount *mp)
 1042 {
 1043 
 1044         return (insmntque1(vp, mp, insmntque_stddtr, NULL));
 1045 }
 1046 
 1047 /*
 1048  * Flush out and invalidate all buffers associated with a bufobj
 1049  * Called with the underlying object locked.
 1050  */
 1051 int
 1052 bufobj_invalbuf(struct bufobj *bo, int flags, struct thread *td, int slpflag,
 1053     int slptimeo)
 1054 {
 1055         int error;
 1056 
 1057         BO_LOCK(bo);
 1058         if (flags & V_SAVE) {
 1059                 error = bufobj_wwait(bo, slpflag, slptimeo);
 1060                 if (error) {
 1061                         BO_UNLOCK(bo);
 1062                         return (error);
 1063                 }
 1064                 if (bo->bo_dirty.bv_cnt > 0) {
 1065                         BO_UNLOCK(bo);
 1066                         if ((error = BO_SYNC(bo, MNT_WAIT, td)) != 0)
 1067                                 return (error);
 1068                         /*
 1069                          * XXX We could save a lock/unlock if this was only
 1070                          * enabled under INVARIANTS
 1071                          */
 1072                         BO_LOCK(bo);
 1073                         if (bo->bo_numoutput > 0 || bo->bo_dirty.bv_cnt > 0)
 1074                                 panic("vinvalbuf: dirty bufs");
 1075                 }
 1076         }
 1077         /*
 1078          * If you alter this loop please notice that interlock is dropped and
 1079          * reacquired in flushbuflist.  Special care is needed to ensure that
 1080          * no race conditions occur from this.
 1081          */
 1082         do {
 1083                 error = flushbuflist(&bo->bo_clean,
 1084                     flags, bo, slpflag, slptimeo);
 1085                 if (error == 0)
 1086                         error = flushbuflist(&bo->bo_dirty,
 1087                             flags, bo, slpflag, slptimeo);
 1088                 if (error != 0 && error != EAGAIN) {
 1089                         BO_UNLOCK(bo);
 1090                         return (error);
 1091                 }
 1092         } while (error != 0);
 1093 
 1094         /*
 1095          * Wait for I/O to complete.  XXX needs cleaning up.  The vnode can
 1096          * have write I/O in-progress but if there is a VM object then the
 1097          * VM object can also have read-I/O in-progress.
 1098          */
 1099         do {
 1100                 bufobj_wwait(bo, 0, 0);
 1101                 BO_UNLOCK(bo);
 1102                 if (bo->bo_object != NULL) {
 1103                         VM_OBJECT_LOCK(bo->bo_object);
 1104                         vm_object_pip_wait(bo->bo_object, "bovlbx");
 1105                         VM_OBJECT_UNLOCK(bo->bo_object);
 1106                 }
 1107                 BO_LOCK(bo);
 1108         } while (bo->bo_numoutput > 0);
 1109         BO_UNLOCK(bo);
 1110 
 1111         /*
 1112          * Destroy the copy in the VM cache, too.
 1113          */
 1114         if (bo->bo_object != NULL) {
 1115                 VM_OBJECT_LOCK(bo->bo_object);
 1116                 vm_object_page_remove(bo->bo_object, 0, 0,
 1117                         (flags & V_SAVE) ? TRUE : FALSE);
 1118                 VM_OBJECT_UNLOCK(bo->bo_object);
 1119         }
 1120 
 1121 #ifdef INVARIANTS
 1122         BO_LOCK(bo);
 1123         if ((flags & (V_ALT | V_NORMAL)) == 0 &&
 1124             (bo->bo_dirty.bv_cnt > 0 || bo->bo_clean.bv_cnt > 0))
 1125                 panic("vinvalbuf: flush failed");
 1126         BO_UNLOCK(bo);
 1127 #endif
 1128         return (0);
 1129 }
 1130 
 1131 /*
 1132  * Flush out and invalidate all buffers associated with a vnode.
 1133  * Called with the underlying object locked.
 1134  */
 1135 int
 1136 vinvalbuf(struct vnode *vp, int flags, struct thread *td, int slpflag,
 1137     int slptimeo)
 1138 {
 1139 
 1140         CTR2(KTR_VFS, "vinvalbuf vp %p flags %d", vp, flags);
 1141         ASSERT_VOP_LOCKED(vp, "vinvalbuf");
 1142         return (bufobj_invalbuf(&vp->v_bufobj, flags, td, slpflag, slptimeo));
 1143 }
 1144 
 1145 /*
 1146  * Flush out buffers on the specified list.
 1147  *
 1148  */
 1149 static int
 1150 flushbuflist( struct bufv *bufv, int flags, struct bufobj *bo, int slpflag,
 1151     int slptimeo)
 1152 {
 1153         struct buf *bp, *nbp;
 1154         int retval, error;
 1155         daddr_t lblkno;
 1156         b_xflags_t xflags;
 1157 
 1158         ASSERT_BO_LOCKED(bo);
 1159 
 1160         retval = 0;
 1161         TAILQ_FOREACH_SAFE(bp, &bufv->bv_hd, b_bobufs, nbp) {
 1162                 if (((flags & V_NORMAL) && (bp->b_xflags & BX_ALTDATA)) ||
 1163                     ((flags & V_ALT) && (bp->b_xflags & BX_ALTDATA) == 0)) {
 1164                         continue;
 1165                 }
 1166                 lblkno = 0;
 1167                 xflags = 0;
 1168                 if (nbp != NULL) {
 1169                         lblkno = nbp->b_lblkno;
 1170                         xflags = nbp->b_xflags &
 1171                                 (BX_BKGRDMARKER | BX_VNDIRTY | BX_VNCLEAN);
 1172                 }
 1173                 retval = EAGAIN;
 1174                 error = BUF_TIMELOCK(bp,
 1175                     LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK, BO_MTX(bo),
 1176                     "flushbuf", slpflag, slptimeo);
 1177                 if (error) {
 1178                         BO_LOCK(bo);
 1179                         return (error != ENOLCK ? error : EAGAIN);
 1180                 }
 1181                 KASSERT(bp->b_bufobj == bo,
 1182                     ("bp %p wrong b_bufobj %p should be %p",
 1183                     bp, bp->b_bufobj, bo));
 1184                 if (bp->b_bufobj != bo) {       /* XXX: necessary ? */
 1185                         BUF_UNLOCK(bp);
 1186                         BO_LOCK(bo);
 1187                         return (EAGAIN);
 1188                 }
 1189                 /*
 1190                  * XXX Since there are no node locks for NFS, I
 1191                  * believe there is a slight chance that a delayed
 1192                  * write will occur while sleeping just above, so
 1193                  * check for it.
 1194                  */
 1195                 if (((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) &&
 1196                     (flags & V_SAVE)) {
 1197                         bremfree(bp);
 1198                         bp->b_flags |= B_ASYNC;
 1199                         bwrite(bp);
 1200                         BO_LOCK(bo);
 1201                         return (EAGAIN);        /* XXX: why not loop ? */
 1202                 }
 1203                 bremfree(bp);
 1204                 bp->b_flags |= (B_INVAL | B_RELBUF);
 1205                 bp->b_flags &= ~B_ASYNC;
 1206                 brelse(bp);
 1207                 BO_LOCK(bo);
 1208                 if (nbp != NULL &&
 1209                     (nbp->b_bufobj != bo ||
 1210                      nbp->b_lblkno != lblkno ||
 1211                      (nbp->b_xflags &
 1212                       (BX_BKGRDMARKER | BX_VNDIRTY | BX_VNCLEAN)) != xflags))
 1213                         break;                  /* nbp invalid */
 1214         }
 1215         return (retval);
 1216 }
 1217 
 1218 /*
 1219  * Truncate a file's buffer and pages to a specified length.  This
 1220  * is in lieu of the old vinvalbuf mechanism, which performed unneeded
 1221  * sync activity.
 1222  */
 1223 int
 1224 vtruncbuf(struct vnode *vp, struct ucred *cred, struct thread *td,
 1225     off_t length, int blksize)
 1226 {
 1227         struct buf *bp, *nbp;
 1228         int anyfreed;
 1229         int trunclbn;
 1230         struct bufobj *bo;
 1231 
 1232         CTR2(KTR_VFS, "vtruncbuf vp %p length %jd", vp, length);
 1233         /*
 1234          * Round up to the *next* lbn.
 1235          */
 1236         trunclbn = (length + blksize - 1) / blksize;
 1237 
 1238         ASSERT_VOP_LOCKED(vp, "vtruncbuf");
 1239 restart:
 1240         VI_LOCK(vp);
 1241         bo = &vp->v_bufobj;
 1242         anyfreed = 1;
 1243         for (;anyfreed;) {
 1244                 anyfreed = 0;
 1245                 TAILQ_FOREACH_SAFE(bp, &bo->bo_clean.bv_hd, b_bobufs, nbp) {
 1246                         if (bp->b_lblkno < trunclbn)
 1247                                 continue;
 1248                         if (BUF_LOCK(bp,
 1249                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1250                             VI_MTX(vp)) == ENOLCK)
 1251                                 goto restart;
 1252 
 1253                         bremfree(bp);
 1254                         bp->b_flags |= (B_INVAL | B_RELBUF);
 1255                         bp->b_flags &= ~B_ASYNC;
 1256                         brelse(bp);
 1257                         anyfreed = 1;
 1258 
 1259                         if (nbp != NULL &&
 1260                             (((nbp->b_xflags & BX_VNCLEAN) == 0) ||
 1261                             (nbp->b_vp != vp) ||
 1262                             (nbp->b_flags & B_DELWRI))) {
 1263                                 goto restart;
 1264                         }
 1265                         VI_LOCK(vp);
 1266                 }
 1267 
 1268                 TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
 1269                         if (bp->b_lblkno < trunclbn)
 1270                                 continue;
 1271                         if (BUF_LOCK(bp,
 1272                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1273                             VI_MTX(vp)) == ENOLCK)
 1274                                 goto restart;
 1275                         bremfree(bp);
 1276                         bp->b_flags |= (B_INVAL | B_RELBUF);
 1277                         bp->b_flags &= ~B_ASYNC;
 1278                         brelse(bp);
 1279                         anyfreed = 1;
 1280                         if (nbp != NULL &&
 1281                             (((nbp->b_xflags & BX_VNDIRTY) == 0) ||
 1282                             (nbp->b_vp != vp) ||
 1283                             (nbp->b_flags & B_DELWRI) == 0)) {
 1284                                 goto restart;
 1285                         }
 1286                         VI_LOCK(vp);
 1287                 }
 1288         }
 1289 
 1290         if (length > 0) {
 1291 restartsync:
 1292                 TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
 1293                         if (bp->b_lblkno > 0)
 1294                                 continue;
 1295                         /*
 1296                          * Since we hold the vnode lock this should only
 1297                          * fail if we're racing with the buf daemon.
 1298                          */
 1299                         if (BUF_LOCK(bp,
 1300                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1301                             VI_MTX(vp)) == ENOLCK) {
 1302                                 goto restart;
 1303                         }
 1304                         VNASSERT((bp->b_flags & B_DELWRI), vp,
 1305                             ("buf(%p) on dirty queue without DELWRI", bp));
 1306 
 1307                         bremfree(bp);
 1308                         bawrite(bp);
 1309                         VI_LOCK(vp);
 1310                         goto restartsync;
 1311                 }
 1312         }
 1313 
 1314         bufobj_wwait(bo, 0, 0);
 1315         VI_UNLOCK(vp);
 1316         vnode_pager_setsize(vp, length);
 1317 
 1318         return (0);
 1319 }
 1320 
 1321 /*
 1322  * buf_splay() - splay tree core for the clean/dirty list of buffers in
 1323  *               a vnode.
 1324  *
 1325  *      NOTE: We have to deal with the special case of a background bitmap
 1326  *      buffer, a situation where two buffers will have the same logical
 1327  *      block offset.  We want (1) only the foreground buffer to be accessed
 1328  *      in a lookup and (2) must differentiate between the foreground and
 1329  *      background buffer in the splay tree algorithm because the splay
 1330  *      tree cannot normally handle multiple entities with the same 'index'.
 1331  *      We accomplish this by adding differentiating flags to the splay tree's
 1332  *      numerical domain.
 1333  */
 1334 static
 1335 struct buf *
 1336 buf_splay(daddr_t lblkno, b_xflags_t xflags, struct buf *root)
 1337 {
 1338         struct buf dummy;
 1339         struct buf *lefttreemax, *righttreemin, *y;
 1340 
 1341         if (root == NULL)
 1342                 return (NULL);
 1343         lefttreemax = righttreemin = &dummy;
 1344         for (;;) {
 1345                 if (lblkno < root->b_lblkno ||
 1346                     (lblkno == root->b_lblkno &&
 1347                     (xflags & BX_BKGRDMARKER) < (root->b_xflags & BX_BKGRDMARKER))) {
 1348                         if ((y = root->b_left) == NULL)
 1349                                 break;
 1350                         if (lblkno < y->b_lblkno) {
 1351                                 /* Rotate right. */
 1352                                 root->b_left = y->b_right;
 1353                                 y->b_right = root;
 1354                                 root = y;
 1355                                 if ((y = root->b_left) == NULL)
 1356                                         break;
 1357                         }
 1358                         /* Link into the new root's right tree. */
 1359                         righttreemin->b_left = root;
 1360                         righttreemin = root;
 1361                 } else if (lblkno > root->b_lblkno ||
 1362                     (lblkno == root->b_lblkno &&
 1363                     (xflags & BX_BKGRDMARKER) > (root->b_xflags & BX_BKGRDMARKER))) {
 1364                         if ((y = root->b_right) == NULL)
 1365                                 break;
 1366                         if (lblkno > y->b_lblkno) {
 1367                                 /* Rotate left. */
 1368                                 root->b_right = y->b_left;
 1369                                 y->b_left = root;
 1370                                 root = y;
 1371                                 if ((y = root->b_right) == NULL)
 1372                                         break;
 1373                         }
 1374                         /* Link into the new root's left tree. */
 1375                         lefttreemax->b_right = root;
 1376                         lefttreemax = root;
 1377                 } else {
 1378                         break;
 1379                 }
 1380                 root = y;
 1381         }
 1382         /* Assemble the new root. */
 1383         lefttreemax->b_right = root->b_left;
 1384         righttreemin->b_left = root->b_right;
 1385         root->b_left = dummy.b_right;
 1386         root->b_right = dummy.b_left;
 1387         return (root);
 1388 }
 1389 
 1390 static void
 1391 buf_vlist_remove(struct buf *bp)
 1392 {
 1393         struct buf *root;
 1394         struct bufv *bv;
 1395 
 1396         KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
 1397         ASSERT_BO_LOCKED(bp->b_bufobj);
 1398         KASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) !=
 1399             (BX_VNDIRTY|BX_VNCLEAN),
 1400             ("buf_vlist_remove: Buf %p is on two lists", bp));
 1401         if (bp->b_xflags & BX_VNDIRTY)
 1402                 bv = &bp->b_bufobj->bo_dirty;
 1403         else
 1404                 bv = &bp->b_bufobj->bo_clean;
 1405         if (bp != bv->bv_root) {
 1406                 root = buf_splay(bp->b_lblkno, bp->b_xflags, bv->bv_root);
 1407                 KASSERT(root == bp, ("splay lookup failed in remove"));
 1408         }
 1409         if (bp->b_left == NULL) {
 1410                 root = bp->b_right;
 1411         } else {
 1412                 root = buf_splay(bp->b_lblkno, bp->b_xflags, bp->b_left);
 1413                 root->b_right = bp->b_right;
 1414         }
 1415         bv->bv_root = root;
 1416         TAILQ_REMOVE(&bv->bv_hd, bp, b_bobufs);
 1417         bv->bv_cnt--;
 1418         bp->b_xflags &= ~(BX_VNDIRTY | BX_VNCLEAN);
 1419 }
 1420 
 1421 /*
 1422  * Add the buffer to the sorted clean or dirty block list using a
 1423  * splay tree algorithm.
 1424  *
 1425  * NOTE: xflags is passed as a constant, optimizing this inline function!
 1426  */
 1427 static void
 1428 buf_vlist_add(struct buf *bp, struct bufobj *bo, b_xflags_t xflags)
 1429 {
 1430         struct buf *root;
 1431         struct bufv *bv;
 1432 
 1433         ASSERT_BO_LOCKED(bo);
 1434         KASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) == 0,
 1435             ("buf_vlist_add: Buf %p has existing xflags %d", bp, bp->b_xflags));
 1436         bp->b_xflags |= xflags;
 1437         if (xflags & BX_VNDIRTY)
 1438                 bv = &bo->bo_dirty;
 1439         else
 1440                 bv = &bo->bo_clean;
 1441 
 1442         root = buf_splay(bp->b_lblkno, bp->b_xflags, bv->bv_root);
 1443         if (root == NULL) {
 1444                 bp->b_left = NULL;
 1445                 bp->b_right = NULL;
 1446                 TAILQ_INSERT_TAIL(&bv->bv_hd, bp, b_bobufs);
 1447         } else if (bp->b_lblkno < root->b_lblkno ||
 1448             (bp->b_lblkno == root->b_lblkno &&
 1449             (bp->b_xflags & BX_BKGRDMARKER) < (root->b_xflags & BX_BKGRDMARKER))) {
 1450                 bp->b_left = root->b_left;
 1451                 bp->b_right = root;
 1452                 root->b_left = NULL;
 1453                 TAILQ_INSERT_BEFORE(root, bp, b_bobufs);
 1454         } else {
 1455                 bp->b_right = root->b_right;
 1456                 bp->b_left = root;
 1457                 root->b_right = NULL;
 1458                 TAILQ_INSERT_AFTER(&bv->bv_hd, root, bp, b_bobufs);
 1459         }
 1460         bv->bv_cnt++;
 1461         bv->bv_root = bp;
 1462 }
 1463 
 1464 /*
 1465  * Lookup a buffer using the splay tree.  Note that we specifically avoid
 1466  * shadow buffers used in background bitmap writes.
 1467  *
 1468  * This code isn't quite efficient as it could be because we are maintaining
 1469  * two sorted lists and do not know which list the block resides in.
 1470  *
 1471  * During a "make buildworld" the desired buffer is found at one of
 1472  * the roots more than 60% of the time.  Thus, checking both roots
 1473  * before performing either splay eliminates unnecessary splays on the
 1474  * first tree splayed.
 1475  */
 1476 struct buf *
 1477 gbincore(struct bufobj *bo, daddr_t lblkno)
 1478 {
 1479         struct buf *bp;
 1480 
 1481         ASSERT_BO_LOCKED(bo);
 1482         if ((bp = bo->bo_clean.bv_root) != NULL &&
 1483             bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1484                 return (bp);
 1485         if ((bp = bo->bo_dirty.bv_root) != NULL &&
 1486             bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1487                 return (bp);
 1488         if ((bp = bo->bo_clean.bv_root) != NULL) {
 1489                 bo->bo_clean.bv_root = bp = buf_splay(lblkno, 0, bp);
 1490                 if (bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1491                         return (bp);
 1492         }
 1493         if ((bp = bo->bo_dirty.bv_root) != NULL) {
 1494                 bo->bo_dirty.bv_root = bp = buf_splay(lblkno, 0, bp);
 1495                 if (bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1496                         return (bp);
 1497         }
 1498         return (NULL);
 1499 }
 1500 
 1501 /*
 1502  * Associate a buffer with a vnode.
 1503  */
 1504 void
 1505 bgetvp(struct vnode *vp, struct buf *bp)
 1506 {
 1507 
 1508         VNASSERT(bp->b_vp == NULL, bp->b_vp, ("bgetvp: not free"));
 1509 
 1510         CTR3(KTR_BUF, "bgetvp(%p) vp %p flags %X", bp, vp, bp->b_flags);
 1511         VNASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) == 0, vp,
 1512             ("bgetvp: bp already attached! %p", bp));
 1513 
 1514         ASSERT_VI_LOCKED(vp, "bgetvp");
 1515         vholdl(vp);
 1516         if (VFS_NEEDSGIANT(vp->v_mount) ||
 1517             vp->v_bufobj.bo_flag & BO_NEEDSGIANT)
 1518                 bp->b_flags |= B_NEEDSGIANT;
 1519         bp->b_vp = vp;
 1520         bp->b_bufobj = &vp->v_bufobj;
 1521         /*
 1522          * Insert onto list for new vnode.
 1523          */
 1524         buf_vlist_add(bp, &vp->v_bufobj, BX_VNCLEAN);
 1525 }
 1526 
 1527 /*
 1528  * Disassociate a buffer from a vnode.
 1529  */
 1530 void
 1531 brelvp(struct buf *bp)
 1532 {
 1533         struct bufobj *bo;
 1534         struct vnode *vp;
 1535 
 1536         CTR3(KTR_BUF, "brelvp(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
 1537         KASSERT(bp->b_vp != NULL, ("brelvp: NULL"));
 1538 
 1539         /*
 1540          * Delete from old vnode list, if on one.
 1541          */
 1542         vp = bp->b_vp;          /* XXX */
 1543         bo = bp->b_bufobj;
 1544         BO_LOCK(bo);
 1545         if (bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN))
 1546                 buf_vlist_remove(bp);
 1547         else
 1548                 panic("brelvp: Buffer %p not on queue.", bp);
 1549         if ((bo->bo_flag & BO_ONWORKLST) && bo->bo_dirty.bv_cnt == 0) {
 1550                 bo->bo_flag &= ~BO_ONWORKLST;
 1551                 mtx_lock(&sync_mtx);
 1552                 LIST_REMOVE(bo, bo_synclist);
 1553                 syncer_worklist_len--;
 1554                 mtx_unlock(&sync_mtx);
 1555         }
 1556         bp->b_flags &= ~B_NEEDSGIANT;
 1557         bp->b_vp = NULL;
 1558         bp->b_bufobj = NULL;
 1559         vdropl(vp);
 1560 }
 1561 
 1562 /*
 1563  * Add an item to the syncer work queue.
 1564  */
 1565 static void
 1566 vn_syncer_add_to_worklist(struct bufobj *bo, int delay)
 1567 {
 1568         int slot;
 1569 
 1570         ASSERT_BO_LOCKED(bo);
 1571 
 1572         mtx_lock(&sync_mtx);
 1573         if (bo->bo_flag & BO_ONWORKLST)
 1574                 LIST_REMOVE(bo, bo_synclist);
 1575         else {
 1576                 bo->bo_flag |= BO_ONWORKLST;
 1577                 syncer_worklist_len++;
 1578         }
 1579 
 1580         if (delay > syncer_maxdelay - 2)
 1581                 delay = syncer_maxdelay - 2;
 1582         slot = (syncer_delayno + delay) & syncer_mask;
 1583 
 1584         LIST_INSERT_HEAD(&syncer_workitem_pending[slot], bo, bo_synclist);
 1585         mtx_unlock(&sync_mtx);
 1586 }
 1587 
 1588 static int
 1589 sysctl_vfs_worklist_len(SYSCTL_HANDLER_ARGS)
 1590 {
 1591         int error, len;
 1592 
 1593         mtx_lock(&sync_mtx);
 1594         len = syncer_worklist_len - sync_vnode_count;
 1595         mtx_unlock(&sync_mtx);
 1596         error = SYSCTL_OUT(req, &len, sizeof(len));
 1597         return (error);
 1598 }
 1599 
 1600 SYSCTL_PROC(_vfs, OID_AUTO, worklist_len, CTLTYPE_INT | CTLFLAG_RD, NULL, 0,
 1601     sysctl_vfs_worklist_len, "I", "Syncer thread worklist length");
 1602 
 1603 static struct proc *updateproc;
 1604 static void sched_sync(void);
 1605 static struct kproc_desc up_kp = {
 1606         "syncer",
 1607         sched_sync,
 1608         &updateproc
 1609 };
 1610 SYSINIT(syncer, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &up_kp);
 1611 
 1612 static int
 1613 sync_vnode(struct synclist *slp, struct bufobj **bo, struct thread *td)
 1614 {
 1615         struct vnode *vp;
 1616         struct mount *mp;
 1617         int vfslocked;
 1618 
 1619         vfslocked = 0;
 1620 restart:
 1621         *bo = LIST_FIRST(slp);
 1622         if (*bo == NULL) {
 1623                 VFS_UNLOCK_GIANT(vfslocked);
 1624                 return (0);
 1625         }
 1626         vp = (*bo)->__bo_vnode; /* XXX */
 1627         if (VFS_NEEDSGIANT(vp->v_mount)) {
 1628                 if (!vfslocked) {
 1629                         vfslocked = 1;
 1630                         if (mtx_trylock(&Giant) == 0) {
 1631                                 mtx_unlock(&sync_mtx);
 1632                                 mtx_lock(&Giant);
 1633                                 mtx_lock(&sync_mtx);
 1634                                 goto restart;
 1635                         }
 1636                 }
 1637         } else {
 1638                 VFS_UNLOCK_GIANT(vfslocked);
 1639                 vfslocked = 0;
 1640         }
 1641         if (VOP_ISLOCKED(vp, NULL) != 0) {
 1642                 VFS_UNLOCK_GIANT(vfslocked);
 1643                 return (1);
 1644         }
 1645         if (VI_TRYLOCK(vp) == 0) {
 1646                 VFS_UNLOCK_GIANT(vfslocked);
 1647                 return (1);
 1648         }
 1649         /*
 1650          * We use vhold in case the vnode does not
 1651          * successfully sync.  vhold prevents the vnode from
 1652          * going away when we unlock the sync_mtx so that
 1653          * we can acquire the vnode interlock.
 1654          */
 1655         vholdl(vp);
 1656         mtx_unlock(&sync_mtx);
 1657         VI_UNLOCK(vp);
 1658         if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
 1659                 vdrop(vp);
 1660                 VFS_UNLOCK_GIANT(vfslocked);
 1661                 mtx_lock(&sync_mtx);
 1662                 return (*bo == LIST_FIRST(slp));
 1663         }
 1664         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1665         (void) VOP_FSYNC(vp, MNT_LAZY, td);
 1666         VOP_UNLOCK(vp, 0, td);
 1667         vn_finished_write(mp);
 1668         VI_LOCK(vp);
 1669         if (((*bo)->bo_flag & BO_ONWORKLST) != 0) {
 1670                 /*
 1671                  * Put us back on the worklist.  The worklist
 1672                  * routine will remove us from our current
 1673                  * position and then add us back in at a later
 1674                  * position.
 1675                  */
 1676                 vn_syncer_add_to_worklist(*bo, syncdelay);
 1677         }
 1678         vdropl(vp);
 1679         VFS_UNLOCK_GIANT(vfslocked);
 1680         mtx_lock(&sync_mtx);
 1681         return (0);
 1682 }
 1683 
 1684 /*
 1685  * System filesystem synchronizer daemon.
 1686  */
 1687 static void
 1688 sched_sync(void)
 1689 {
 1690         struct synclist *next;
 1691         struct synclist *slp;
 1692         struct bufobj *bo;
 1693         long starttime;
 1694         struct thread *td = curthread;
 1695         static int dummychan;
 1696         int last_work_seen;
 1697         int net_worklist_len;
 1698         int syncer_final_iter;
 1699         int first_printf;
 1700         int error;
 1701 
 1702         last_work_seen = 0;
 1703         syncer_final_iter = 0;
 1704         first_printf = 1;
 1705         syncer_state = SYNCER_RUNNING;
 1706         starttime = time_uptime;
 1707         td->td_pflags |= TDP_NORUNNINGBUF;
 1708 
 1709         EVENTHANDLER_REGISTER(shutdown_pre_sync, syncer_shutdown, td->td_proc,
 1710             SHUTDOWN_PRI_LAST);
 1711 
 1712         mtx_lock(&sync_mtx);
 1713         for (;;) {
 1714                 if (syncer_state == SYNCER_FINAL_DELAY &&
 1715                     syncer_final_iter == 0) {
 1716                         mtx_unlock(&sync_mtx);
 1717                         kthread_suspend_check(td->td_proc);
 1718                         mtx_lock(&sync_mtx);
 1719                 }
 1720                 net_worklist_len = syncer_worklist_len - sync_vnode_count;
 1721                 if (syncer_state != SYNCER_RUNNING &&
 1722                     starttime != time_uptime) {
 1723                         if (first_printf) {
 1724                                 printf("\nSyncing disks, vnodes remaining...");
 1725                                 first_printf = 0;
 1726                         }
 1727                         printf("%d ", net_worklist_len);
 1728                 }
 1729                 starttime = time_uptime;
 1730 
 1731                 /*
 1732                  * Push files whose dirty time has expired.  Be careful
 1733                  * of interrupt race on slp queue.
 1734                  *
 1735                  * Skip over empty worklist slots when shutting down.
 1736                  */
 1737                 do {
 1738                         slp = &syncer_workitem_pending[syncer_delayno];
 1739                         syncer_delayno += 1;
 1740                         if (syncer_delayno == syncer_maxdelay)
 1741                                 syncer_delayno = 0;
 1742                         next = &syncer_workitem_pending[syncer_delayno];
 1743                         /*
 1744                          * If the worklist has wrapped since the
 1745                          * it was emptied of all but syncer vnodes,
 1746                          * switch to the FINAL_DELAY state and run
 1747                          * for one more second.
 1748                          */
 1749                         if (syncer_state == SYNCER_SHUTTING_DOWN &&
 1750                             net_worklist_len == 0 &&
 1751                             last_work_seen == syncer_delayno) {
 1752                                 syncer_state = SYNCER_FINAL_DELAY;
 1753                                 syncer_final_iter = SYNCER_SHUTDOWN_SPEEDUP;
 1754                         }
 1755                 } while (syncer_state != SYNCER_RUNNING && LIST_EMPTY(slp) &&
 1756                     syncer_worklist_len > 0);
 1757 
 1758                 /*
 1759                  * Keep track of the last time there was anything
 1760                  * on the worklist other than syncer vnodes.
 1761                  * Return to the SHUTTING_DOWN state if any
 1762                  * new work appears.
 1763                  */
 1764                 if (net_worklist_len > 0 || syncer_state == SYNCER_RUNNING)
 1765                         last_work_seen = syncer_delayno;
 1766                 if (net_worklist_len > 0 && syncer_state == SYNCER_FINAL_DELAY)
 1767                         syncer_state = SYNCER_SHUTTING_DOWN;
 1768                 while (!LIST_EMPTY(slp)) {
 1769                         error = sync_vnode(slp, &bo, td);
 1770                         if (error == 1) {
 1771                                 LIST_REMOVE(bo, bo_synclist);
 1772                                 LIST_INSERT_HEAD(next, bo, bo_synclist);
 1773                                 continue;
 1774                         }
 1775                 }
 1776                 if (syncer_state == SYNCER_FINAL_DELAY && syncer_final_iter > 0)
 1777                         syncer_final_iter--;
 1778                 /*
 1779                  * The variable rushjob allows the kernel to speed up the
 1780                  * processing of the filesystem syncer process. A rushjob
 1781                  * value of N tells the filesystem syncer to process the next
 1782                  * N seconds worth of work on its queue ASAP. Currently rushjob
 1783                  * is used by the soft update code to speed up the filesystem
 1784                  * syncer process when the incore state is getting so far
 1785                  * ahead of the disk that the kernel memory pool is being
 1786                  * threatened with exhaustion.
 1787                  */
 1788                 if (rushjob > 0) {
 1789                         rushjob -= 1;
 1790                         continue;
 1791                 }
 1792                 /*
 1793                  * Just sleep for a short period of time between
 1794                  * iterations when shutting down to allow some I/O
 1795                  * to happen.
 1796                  *
 1797                  * If it has taken us less than a second to process the
 1798                  * current work, then wait. Otherwise start right over
 1799                  * again. We can still lose time if any single round
 1800                  * takes more than two seconds, but it does not really
 1801                  * matter as we are just trying to generally pace the
 1802                  * filesystem activity.
 1803                  */
 1804                 if (syncer_state != SYNCER_RUNNING)
 1805                         msleep(&dummychan, &sync_mtx, PPAUSE, "syncfnl",
 1806                             hz / SYNCER_SHUTDOWN_SPEEDUP);
 1807                 else if (time_uptime == starttime)
 1808                         msleep(&lbolt, &sync_mtx, PPAUSE, "syncer", 0);
 1809         }
 1810 }
 1811 
 1812 /*
 1813  * Request the syncer daemon to speed up its work.
 1814  * We never push it to speed up more than half of its
 1815  * normal turn time, otherwise it could take over the cpu.
 1816  */
 1817 int
 1818 speedup_syncer(void)
 1819 {
 1820         struct thread *td;
 1821         int ret = 0;
 1822 
 1823         td = FIRST_THREAD_IN_PROC(updateproc);
 1824         mtx_lock(&sync_mtx);
 1825         if (rushjob < syncdelay / 2) {
 1826                 rushjob += 1;
 1827                 stat_rush_requests += 1;
 1828                 ret = 1;
 1829         }
 1830         mtx_unlock(&sync_mtx);
 1831         sleepq_remove(td, &lbolt);
 1832         return (ret);
 1833 }
 1834 
 1835 /*
 1836  * Tell the syncer to speed up its work and run though its work
 1837  * list several times, then tell it to shut down.
 1838  */
 1839 static void
 1840 syncer_shutdown(void *arg, int howto)
 1841 {
 1842         struct thread *td;
 1843 
 1844         if (howto & RB_NOSYNC)
 1845                 return;
 1846         td = FIRST_THREAD_IN_PROC(updateproc);
 1847         mtx_lock(&sync_mtx);
 1848         syncer_state = SYNCER_SHUTTING_DOWN;
 1849         rushjob = 0;
 1850         mtx_unlock(&sync_mtx);
 1851         sleepq_remove(td, &lbolt);
 1852         kproc_shutdown(arg, howto);
 1853 }
 1854 
 1855 /*
 1856  * Reassign a buffer from one vnode to another.
 1857  * Used to assign file specific control information
 1858  * (indirect blocks) to the vnode to which they belong.
 1859  */
 1860 void
 1861 reassignbuf(struct buf *bp)
 1862 {
 1863         struct vnode *vp;
 1864         struct bufobj *bo;
 1865         int delay;
 1866 #ifdef INVARIANTS
 1867         struct bufv *bv;
 1868 #endif
 1869 
 1870         vp = bp->b_vp;
 1871         bo = bp->b_bufobj;
 1872         ++reassignbufcalls;
 1873 
 1874         CTR3(KTR_BUF, "reassignbuf(%p) vp %p flags %X",
 1875             bp, bp->b_vp, bp->b_flags);
 1876         /*
 1877          * B_PAGING flagged buffers cannot be reassigned because their vp
 1878          * is not fully linked in.
 1879          */
 1880         if (bp->b_flags & B_PAGING)
 1881                 panic("cannot reassign paging buffer");
 1882 
 1883         /*
 1884          * Delete from old vnode list, if on one.
 1885          */
 1886         VI_LOCK(vp);
 1887         if (bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN))
 1888                 buf_vlist_remove(bp);
 1889         else
 1890                 panic("reassignbuf: Buffer %p not on queue.", bp);
 1891         /*
 1892          * If dirty, put on list of dirty buffers; otherwise insert onto list
 1893          * of clean buffers.
 1894          */
 1895         if (bp->b_flags & B_DELWRI) {
 1896                 if ((bo->bo_flag & BO_ONWORKLST) == 0) {
 1897                         switch (vp->v_type) {
 1898                         case VDIR:
 1899                                 delay = dirdelay;
 1900                                 break;
 1901                         case VCHR:
 1902                                 delay = metadelay;
 1903                                 break;
 1904                         default:
 1905                                 delay = filedelay;
 1906                         }
 1907                         vn_syncer_add_to_worklist(bo, delay);
 1908                 }
 1909                 buf_vlist_add(bp, bo, BX_VNDIRTY);
 1910         } else {
 1911                 buf_vlist_add(bp, bo, BX_VNCLEAN);
 1912 
 1913                 if ((bo->bo_flag & BO_ONWORKLST) && bo->bo_dirty.bv_cnt == 0) {
 1914                         mtx_lock(&sync_mtx);
 1915                         LIST_REMOVE(bo, bo_synclist);
 1916                         syncer_worklist_len--;
 1917                         mtx_unlock(&sync_mtx);
 1918                         bo->bo_flag &= ~BO_ONWORKLST;
 1919                 }
 1920         }
 1921 #ifdef INVARIANTS
 1922         bv = &bo->bo_clean;
 1923         bp = TAILQ_FIRST(&bv->bv_hd);
 1924         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1925             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1926         bp = TAILQ_LAST(&bv->bv_hd, buflists);
 1927         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1928             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1929         bv = &bo->bo_dirty;
 1930         bp = TAILQ_FIRST(&bv->bv_hd);
 1931         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1932             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1933         bp = TAILQ_LAST(&bv->bv_hd, buflists);
 1934         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1935             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1936 #endif
 1937         VI_UNLOCK(vp);
 1938 }
 1939 
 1940 /*
 1941  * Increment the use and hold counts on the vnode, taking care to reference
 1942  * the driver's usecount if this is a chardev.  The vholdl() will remove
 1943  * the vnode from the free list if it is presently free.  Requires the
 1944  * vnode interlock and returns with it held.
 1945  */
 1946 static void
 1947 v_incr_usecount(struct vnode *vp)
 1948 {
 1949 
 1950         CTR3(KTR_VFS, "v_incr_usecount: vp %p holdcnt %d usecount %d\n",
 1951             vp, vp->v_holdcnt, vp->v_usecount);
 1952         vp->v_usecount++;
 1953         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 1954                 dev_lock();
 1955                 vp->v_rdev->si_usecount++;
 1956                 dev_unlock();
 1957         }
 1958         vholdl(vp);
 1959 }
 1960 
 1961 /*
 1962  * Turn a holdcnt into a use+holdcnt such that only one call to
 1963  * v_decr_usecount is needed.
 1964  */
 1965 static void
 1966 v_upgrade_usecount(struct vnode *vp)
 1967 {
 1968 
 1969         CTR3(KTR_VFS, "v_upgrade_usecount: vp %p holdcnt %d usecount %d\n",
 1970             vp, vp->v_holdcnt, vp->v_usecount);
 1971         vp->v_usecount++;
 1972         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 1973                 dev_lock();
 1974                 vp->v_rdev->si_usecount++;
 1975                 dev_unlock();
 1976         }
 1977 }
 1978 
 1979 /*
 1980  * Decrement the vnode use and hold count along with the driver's usecount
 1981  * if this is a chardev.  The vdropl() below releases the vnode interlock
 1982  * as it may free the vnode.
 1983  */
 1984 static void
 1985 v_decr_usecount(struct vnode *vp)
 1986 {
 1987 
 1988         CTR3(KTR_VFS, "v_decr_usecount: vp %p holdcnt %d usecount %d\n",
 1989             vp, vp->v_holdcnt, vp->v_usecount);
 1990         ASSERT_VI_LOCKED(vp, __FUNCTION__);
 1991         VNASSERT(vp->v_usecount > 0, vp,
 1992             ("v_decr_usecount: negative usecount"));
 1993         vp->v_usecount--;
 1994         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 1995                 dev_lock();
 1996                 vp->v_rdev->si_usecount--;
 1997                 dev_unlock();
 1998         }
 1999         vdropl(vp);
 2000 }
 2001 
 2002 /*
 2003  * Decrement only the use count and driver use count.  This is intended to
 2004  * be paired with a follow on vdropl() to release the remaining hold count.
 2005  * In this way we may vgone() a vnode with a 0 usecount without risk of
 2006  * having it end up on a free list because the hold count is kept above 0.
 2007  */
 2008 static void
 2009 v_decr_useonly(struct vnode *vp)
 2010 {
 2011 
 2012         CTR3(KTR_VFS, "v_decr_useonly: vp %p holdcnt %d usecount %d\n",
 2013             vp, vp->v_holdcnt, vp->v_usecount);
 2014         ASSERT_VI_LOCKED(vp, __FUNCTION__);
 2015         VNASSERT(vp->v_usecount > 0, vp,
 2016             ("v_decr_useonly: negative usecount"));
 2017         vp->v_usecount--;
 2018         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 2019                 dev_lock();
 2020                 vp->v_rdev->si_usecount--;
 2021                 dev_unlock();
 2022         }
 2023 }
 2024 
 2025 /*
 2026  * Grab a particular vnode from the free list, increment its
 2027  * reference count and lock it. The vnode lock bit is set if the
 2028  * vnode is being eliminated in vgone. The process is awakened
 2029  * when the transition is completed, and an error returned to
 2030  * indicate that the vnode is no longer usable (possibly having
 2031  * been changed to a new filesystem type).
 2032  */
 2033 int
 2034 vget(struct vnode *vp, int flags, struct thread *td)
 2035 {
 2036         int oweinact;
 2037         int oldflags;
 2038         int error;
 2039 
 2040         error = 0;
 2041         oldflags = flags;
 2042         oweinact = 0;
 2043         VFS_ASSERT_GIANT(vp->v_mount);
 2044         if ((flags & LK_INTERLOCK) == 0)
 2045                 VI_LOCK(vp);
 2046         /*
 2047          * If the inactive call was deferred because vput() was called
 2048          * with a shared lock, we have to do it here before another thread
 2049          * gets a reference to data that should be dead.
 2050          */
 2051         if (vp->v_iflag & VI_OWEINACT) {
 2052                 if (flags & LK_NOWAIT) {
 2053                         VI_UNLOCK(vp);
 2054                         return (EBUSY);
 2055                 }
 2056                 flags &= ~LK_TYPE_MASK;
 2057                 flags |= LK_EXCLUSIVE;
 2058                 oweinact = 1;
 2059         }
 2060         vholdl(vp);
 2061         if ((error = vn_lock(vp, flags | LK_INTERLOCK, td)) != 0) {
 2062                 vdrop(vp);
 2063                 return (error);
 2064         }
 2065         VI_LOCK(vp);
 2066         /* Upgrade our holdcnt to a usecount. */
 2067         v_upgrade_usecount(vp);
 2068         if (vp->v_iflag & VI_DOOMED && (flags & LK_RETRY) == 0)
 2069                 panic("vget: vn_lock failed to return ENOENT\n");
 2070         if (oweinact) {
 2071                 if (vp->v_iflag & VI_OWEINACT)
 2072                         vinactive(vp, td);
 2073                 VI_UNLOCK(vp);
 2074                 if ((oldflags & LK_TYPE_MASK) == 0)
 2075                         VOP_UNLOCK(vp, 0, td);
 2076         } else
 2077                 VI_UNLOCK(vp);
 2078         return (0);
 2079 }
 2080 
 2081 /*
 2082  * Increase the reference count of a vnode.
 2083  */
 2084 void
 2085 vref(struct vnode *vp)
 2086 {
 2087 
 2088         VI_LOCK(vp);
 2089         v_incr_usecount(vp);
 2090         VI_UNLOCK(vp);
 2091 }
 2092 
 2093 /*
 2094  * Return reference count of a vnode.
 2095  *
 2096  * The results of this call are only guaranteed when some mechanism other
 2097  * than the VI lock is used to stop other processes from gaining references
 2098  * to the vnode.  This may be the case if the caller holds the only reference.
 2099  * This is also useful when stale data is acceptable as race conditions may
 2100  * be accounted for by some other means.
 2101  */
 2102 int
 2103 vrefcnt(struct vnode *vp)
 2104 {
 2105         int usecnt;
 2106 
 2107         VI_LOCK(vp);
 2108         usecnt = vp->v_usecount;
 2109         VI_UNLOCK(vp);
 2110 
 2111         return (usecnt);
 2112 }
 2113 
 2114 
 2115 /*
 2116  * Vnode put/release.
 2117  * If count drops to zero, call inactive routine and return to freelist.
 2118  */
 2119 void
 2120 vrele(struct vnode *vp)
 2121 {
 2122         struct thread *td = curthread;  /* XXX */
 2123 
 2124         KASSERT(vp != NULL, ("vrele: null vp"));
 2125         VFS_ASSERT_GIANT(vp->v_mount);
 2126 
 2127         VI_LOCK(vp);
 2128 
 2129         /* Skip this v_writecount check if we're going to panic below. */
 2130         VNASSERT(vp->v_writecount < vp->v_usecount || vp->v_usecount < 1, vp,
 2131             ("vrele: missed vn_close"));
 2132 
 2133         if (vp->v_usecount > 1 || ((vp->v_iflag & VI_DOINGINACT) &&
 2134             vp->v_usecount == 1)) {
 2135                 v_decr_usecount(vp);
 2136                 return;
 2137         }
 2138         if (vp->v_usecount != 1) {
 2139 #ifdef DIAGNOSTIC
 2140                 vprint("vrele: negative ref count", vp);
 2141 #endif
 2142                 VI_UNLOCK(vp);
 2143                 panic("vrele: negative ref cnt");
 2144         }
 2145         /*
 2146          * We want to hold the vnode until the inactive finishes to
 2147          * prevent vgone() races.  We drop the use count here and the
 2148          * hold count below when we're done.
 2149          */
 2150         v_decr_useonly(vp);
 2151         /*
 2152          * We must call VOP_INACTIVE with the node locked. Mark
 2153          * as VI_DOINGINACT to avoid recursion.
 2154          */
 2155         vp->v_iflag |= VI_OWEINACT;
 2156         if (vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK, td) == 0) {
 2157                 VI_LOCK(vp);
 2158                 if (vp->v_usecount > 0)
 2159                         vp->v_iflag &= ~VI_OWEINACT;
 2160                 if (vp->v_iflag & VI_OWEINACT)
 2161                         vinactive(vp, td);
 2162                 VOP_UNLOCK(vp, 0, td);
 2163         } else {
 2164                 VI_LOCK(vp);
 2165                 if (vp->v_usecount > 0)
 2166                         vp->v_iflag &= ~VI_OWEINACT;
 2167         }
 2168         vdropl(vp);
 2169 }
 2170 
 2171 /*
 2172  * Release an already locked vnode.  This give the same effects as
 2173  * unlock+vrele(), but takes less time and avoids releasing and
 2174  * re-aquiring the lock (as vrele() acquires the lock internally.)
 2175  */
 2176 void
 2177 vput(struct vnode *vp)
 2178 {
 2179         struct thread *td = curthread;  /* XXX */
 2180         int error;
 2181 
 2182         KASSERT(vp != NULL, ("vput: null vp"));
 2183         ASSERT_VOP_LOCKED(vp, "vput");
 2184         VFS_ASSERT_GIANT(vp->v_mount);
 2185         VI_LOCK(vp);
 2186         /* Skip this v_writecount check if we're going to panic below. */
 2187         VNASSERT(vp->v_writecount < vp->v_usecount || vp->v_usecount < 1, vp,
 2188             ("vput: missed vn_close"));
 2189         error = 0;
 2190 
 2191         if (vp->v_usecount > 1 || ((vp->v_iflag & VI_DOINGINACT) &&
 2192             vp->v_usecount == 1)) {
 2193                 VOP_UNLOCK(vp, 0, td);
 2194                 v_decr_usecount(vp);
 2195                 return;
 2196         }
 2197 
 2198         if (vp->v_usecount != 1) {
 2199 #ifdef DIAGNOSTIC
 2200                 vprint("vput: negative ref count", vp);
 2201 #endif
 2202                 panic("vput: negative ref cnt");
 2203         }
 2204         /*
 2205          * We want to hold the vnode until the inactive finishes to
 2206          * prevent vgone() races.  We drop the use count here and the
 2207          * hold count below when we're done.
 2208          */
 2209         v_decr_useonly(vp);
 2210         vp->v_iflag |= VI_OWEINACT;
 2211         if (VOP_ISLOCKED(vp, NULL) != LK_EXCLUSIVE) {
 2212                 error = VOP_LOCK(vp, LK_UPGRADE|LK_INTERLOCK|LK_NOWAIT, td);
 2213                 VI_LOCK(vp);
 2214                 if (error) {
 2215                         if (vp->v_usecount > 0)
 2216                                 vp->v_iflag &= ~VI_OWEINACT;
 2217                         goto done;
 2218                 }
 2219         }
 2220         if (vp->v_usecount > 0)
 2221                 vp->v_iflag &= ~VI_OWEINACT;
 2222         if (vp->v_iflag & VI_OWEINACT)
 2223                 vinactive(vp, td);
 2224         VOP_UNLOCK(vp, 0, td);
 2225 done:
 2226         vdropl(vp);
 2227 }
 2228 
 2229 /*
 2230  * Somebody doesn't want the vnode recycled.
 2231  */
 2232 void
 2233 vhold(struct vnode *vp)
 2234 {
 2235 
 2236         VI_LOCK(vp);
 2237         vholdl(vp);
 2238         VI_UNLOCK(vp);
 2239 }
 2240 
 2241 void
 2242 vholdl(struct vnode *vp)
 2243 {
 2244 
 2245         vp->v_holdcnt++;
 2246         if (VSHOULDBUSY(vp))
 2247                 vbusy(vp);
 2248 }
 2249 
 2250 /*
 2251  * Note that there is one less who cares about this vnode.  vdrop() is the
 2252  * opposite of vhold().
 2253  */
 2254 void
 2255 vdrop(struct vnode *vp)
 2256 {
 2257 
 2258         VI_LOCK(vp);
 2259         vdropl(vp);
 2260 }
 2261 
 2262 /*
 2263  * Drop the hold count of the vnode.  If this is the last reference to
 2264  * the vnode we will free it if it has been vgone'd otherwise it is
 2265  * placed on the free list.
 2266  */
 2267 void
 2268 vdropl(struct vnode *vp)
 2269 {
 2270 
 2271         ASSERT_VI_LOCKED(vp, "vdropl");
 2272         if (vp->v_holdcnt <= 0)
 2273                 panic("vdrop: holdcnt %d", vp->v_holdcnt);
 2274         vp->v_holdcnt--;
 2275         if (vp->v_holdcnt == 0) {
 2276                 if (vp->v_iflag & VI_DOOMED) {
 2277                         vdestroy(vp);
 2278                         return;
 2279                 } else
 2280                         vfree(vp);
 2281         }
 2282         VI_UNLOCK(vp);
 2283 }
 2284 
 2285 /*
 2286  * Call VOP_INACTIVE on the vnode and manage the DOINGINACT and OWEINACT
 2287  * flags.  DOINGINACT prevents us from recursing in calls to vinactive.
 2288  * OWEINACT tracks whether a vnode missed a call to inactive due to a
 2289  * failed lock upgrade.
 2290  */
 2291 static void
 2292 vinactive(struct vnode *vp, struct thread *td)
 2293 {
 2294 
 2295         ASSERT_VOP_LOCKED(vp, "vinactive");
 2296         ASSERT_VI_LOCKED(vp, "vinactive");
 2297         VNASSERT((vp->v_iflag & VI_DOINGINACT) == 0, vp,
 2298             ("vinactive: recursed on VI_DOINGINACT"));
 2299         vp->v_iflag |= VI_DOINGINACT;
 2300         vp->v_iflag &= ~VI_OWEINACT;
 2301         VI_UNLOCK(vp);
 2302         VOP_INACTIVE(vp, td);
 2303         VI_LOCK(vp);
 2304         VNASSERT(vp->v_iflag & VI_DOINGINACT, vp,
 2305             ("vinactive: lost VI_DOINGINACT"));
 2306         vp->v_iflag &= ~VI_DOINGINACT;
 2307 }
 2308 
 2309 /*
 2310  * Remove any vnodes in the vnode table belonging to mount point mp.
 2311  *
 2312  * If FORCECLOSE is not specified, there should not be any active ones,
 2313  * return error if any are found (nb: this is a user error, not a
 2314  * system error). If FORCECLOSE is specified, detach any active vnodes
 2315  * that are found.
 2316  *
 2317  * If WRITECLOSE is set, only flush out regular file vnodes open for
 2318  * writing.
 2319  *
 2320  * SKIPSYSTEM causes any vnodes marked VV_SYSTEM to be skipped.
 2321  *
 2322  * `rootrefs' specifies the base reference count for the root vnode
 2323  * of this filesystem. The root vnode is considered busy if its
 2324  * v_usecount exceeds this value. On a successful return, vflush(, td)
 2325  * will call vrele() on the root vnode exactly rootrefs times.
 2326  * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must
 2327  * be zero.
 2328  */
 2329 #ifdef DIAGNOSTIC
 2330 static int busyprt = 0;         /* print out busy vnodes */
 2331 SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, "");
 2332 #endif
 2333 
 2334 int
 2335 vflush( struct mount *mp, int rootrefs, int flags, struct thread *td)
 2336 {
 2337         struct vnode *vp, *mvp, *rootvp = NULL;
 2338         struct vattr vattr;
 2339         int busy = 0, error;
 2340 
 2341         CTR1(KTR_VFS, "vflush: mp %p", mp);
 2342         if (rootrefs > 0) {
 2343                 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0,
 2344                     ("vflush: bad args"));
 2345                 /*
 2346                  * Get the filesystem root vnode. We can vput() it
 2347                  * immediately, since with rootrefs > 0, it won't go away.
 2348                  */
 2349                 if ((error = VFS_ROOT(mp, LK_EXCLUSIVE, &rootvp, td)) != 0)
 2350                         return (error);
 2351                 vput(rootvp);
 2352 
 2353         }
 2354         MNT_ILOCK(mp);
 2355 loop:
 2356         MNT_VNODE_FOREACH(vp, mp, mvp) {
 2357 
 2358                 VI_LOCK(vp);
 2359                 vholdl(vp);
 2360                 MNT_IUNLOCK(mp);
 2361                 error = vn_lock(vp, LK_INTERLOCK | LK_EXCLUSIVE, td);
 2362                 if (error) {
 2363                         vdrop(vp);
 2364                         MNT_ILOCK(mp);
 2365                         MNT_VNODE_FOREACH_ABORT_ILOCKED(mp, mvp);
 2366                         goto loop;
 2367                 }
 2368                 /*
 2369                  * Skip over a vnodes marked VV_SYSTEM.
 2370                  */
 2371                 if ((flags & SKIPSYSTEM) && (vp->v_vflag & VV_SYSTEM)) {
 2372                         VOP_UNLOCK(vp, 0, td);
 2373                         vdrop(vp);
 2374                         MNT_ILOCK(mp);
 2375                         continue;
 2376                 }
 2377                 /*
 2378                  * If WRITECLOSE is set, flush out unlinked but still open
 2379                  * files (even if open only for reading) and regular file
 2380                  * vnodes open for writing.
 2381                  */
 2382                 if (flags & WRITECLOSE) {
 2383                         error = VOP_GETATTR(vp, &vattr, td->td_ucred, td);
 2384                         VI_LOCK(vp);
 2385 
 2386                         if ((vp->v_type == VNON ||
 2387                             (error == 0 && vattr.va_nlink > 0)) &&
 2388                             (vp->v_writecount == 0 || vp->v_type != VREG)) {
 2389                                 VOP_UNLOCK(vp, 0, td);
 2390                                 vdropl(vp);
 2391                                 MNT_ILOCK(mp);
 2392                                 continue;
 2393                         }
 2394                 } else
 2395                         VI_LOCK(vp);
 2396                 /*
 2397                  * With v_usecount == 0, all we need to do is clear out the
 2398                  * vnode data structures and we are done.
 2399                  *
 2400                  * If FORCECLOSE is set, forcibly close the vnode.
 2401                  */
 2402                 if (vp->v_usecount == 0 || (flags & FORCECLOSE)) {
 2403                         VNASSERT(vp->v_usecount == 0 ||
 2404                             (vp->v_type != VCHR && vp->v_type != VBLK), vp,
 2405                             ("device VNODE %p is FORCECLOSED", vp));
 2406                         vgonel(vp);
 2407                 } else {
 2408                         busy++;
 2409 #ifdef DIAGNOSTIC
 2410                         if (busyprt)
 2411                                 vprint("vflush: busy vnode", vp);
 2412 #endif
 2413                 }
 2414                 VOP_UNLOCK(vp, 0, td);
 2415                 vdropl(vp);
 2416                 MNT_ILOCK(mp);
 2417         }
 2418         MNT_IUNLOCK(mp);
 2419         if (rootrefs > 0 && (flags & FORCECLOSE) == 0) {
 2420                 /*
 2421                  * If just the root vnode is busy, and if its refcount
 2422                  * is equal to `rootrefs', then go ahead and kill it.
 2423                  */
 2424                 VI_LOCK(rootvp);
 2425                 KASSERT(busy > 0, ("vflush: not busy"));
 2426                 VNASSERT(rootvp->v_usecount >= rootrefs, rootvp,
 2427                     ("vflush: usecount %d < rootrefs %d",
 2428                      rootvp->v_usecount, rootrefs));
 2429                 if (busy == 1 && rootvp->v_usecount == rootrefs) {
 2430                         VOP_LOCK(rootvp, LK_EXCLUSIVE|LK_INTERLOCK, td);
 2431                         vgone(rootvp);
 2432                         VOP_UNLOCK(rootvp, 0, td);
 2433                         busy = 0;
 2434                 } else
 2435                         VI_UNLOCK(rootvp);
 2436         }
 2437         if (busy)
 2438                 return (EBUSY);
 2439         for (; rootrefs > 0; rootrefs--)
 2440                 vrele(rootvp);
 2441         return (0);
 2442 }
 2443 
 2444 /*
 2445  * Recycle an unused vnode to the front of the free list.
 2446  */
 2447 int
 2448 vrecycle(struct vnode *vp, struct thread *td)
 2449 {
 2450         int recycled;
 2451 
 2452         ASSERT_VOP_LOCKED(vp, "vrecycle");
 2453         recycled = 0;
 2454         VI_LOCK(vp);
 2455         if (vp->v_usecount == 0) {
 2456                 recycled = 1;
 2457                 vgonel(vp);
 2458         }
 2459         VI_UNLOCK(vp);
 2460         return (recycled);
 2461 }
 2462 
 2463 /*
 2464  * Eliminate all activity associated with a vnode
 2465  * in preparation for reuse.
 2466  */
 2467 void
 2468 vgone(struct vnode *vp)
 2469 {
 2470         VI_LOCK(vp);
 2471         vgonel(vp);
 2472         VI_UNLOCK(vp);
 2473 }
 2474 
 2475 /*
 2476  * vgone, with the vp interlock held.
 2477  */
 2478 void
 2479 vgonel(struct vnode *vp)
 2480 {
 2481         struct thread *td;
 2482         int oweinact;
 2483         int active;
 2484         struct mount *mp;
 2485 
 2486         CTR1(KTR_VFS, "vgonel: vp %p", vp);
 2487         ASSERT_VOP_LOCKED(vp, "vgonel");
 2488         ASSERT_VI_LOCKED(vp, "vgonel");
 2489         VNASSERT(vp->v_holdcnt, vp,
 2490             ("vgonel: vp %p has no reference.", vp));
 2491         td = curthread;
 2492 
 2493         /*
 2494          * Don't vgonel if we're already doomed.
 2495          */
 2496         if (vp->v_iflag & VI_DOOMED)
 2497                 return;
 2498         vp->v_iflag |= VI_DOOMED;
 2499         /*
 2500          * Check to see if the vnode is in use.  If so, we have to call
 2501          * VOP_CLOSE() and VOP_INACTIVE().
 2502          */
 2503         active = vp->v_usecount;
 2504         oweinact = (vp->v_iflag & VI_OWEINACT);
 2505         VI_UNLOCK(vp);
 2506         /*
 2507          * Clean out any buffers associated with the vnode.
 2508          * If the flush fails, just toss the buffers.
 2509          */
 2510         mp = NULL;
 2511         if (!TAILQ_EMPTY(&vp->v_bufobj.bo_dirty.bv_hd))
 2512                 (void) vn_start_secondary_write(vp, &mp, V_WAIT);
 2513         if (vinvalbuf(vp, V_SAVE, td, 0, 0) != 0)
 2514                 vinvalbuf(vp, 0, td, 0, 0);
 2515 
 2516         /*
 2517          * If purging an active vnode, it must be closed and
 2518          * deactivated before being reclaimed.
 2519          */
 2520         if (active)
 2521                 VOP_CLOSE(vp, FNONBLOCK, NOCRED, td);
 2522         if (oweinact || active) {
 2523                 VI_LOCK(vp);
 2524                 if ((vp->v_iflag & VI_DOINGINACT) == 0)
 2525                         vinactive(vp, td);
 2526                 VI_UNLOCK(vp);
 2527         }
 2528         /*
 2529          * Reclaim the vnode.
 2530          */
 2531         if (VOP_RECLAIM(vp, td))
 2532                 panic("vgone: cannot reclaim");
 2533         if (mp != NULL)
 2534                 vn_finished_secondary_write(mp);
 2535         VNASSERT(vp->v_object == NULL, vp,
 2536             ("vop_reclaim left v_object vp=%p, tag=%s", vp, vp->v_tag));
 2537         /*
 2538          * Clear the advisory locks and wake up waiting threads.
 2539          */
 2540         lf_purgelocks(vp, &(vp->v_lockf));
 2541         /*
 2542          * Delete from old mount point vnode list.
 2543          */
 2544         delmntque(vp);
 2545         cache_purge(vp);
 2546         /*
 2547          * Done with purge, reset to the standard lock and invalidate
 2548          * the vnode.
 2549          */
 2550         VI_LOCK(vp);
 2551         vp->v_vnlock = &vp->v_lock;
 2552         vp->v_op = &dead_vnodeops;
 2553         vp->v_tag = "none";
 2554         vp->v_type = VBAD;
 2555 }
 2556 
 2557 /*
 2558  * Calculate the total number of references to a special device.
 2559  */
 2560 int
 2561 vcount(struct vnode *vp)
 2562 {
 2563         int count;
 2564 
 2565         dev_lock();
 2566         count = vp->v_rdev->si_usecount;
 2567         dev_unlock();
 2568         return (count);
 2569 }
 2570 
 2571 /*
 2572  * Same as above, but using the struct cdev *as argument
 2573  */
 2574 int
 2575 count_dev(struct cdev *dev)
 2576 {
 2577         int count;
 2578 
 2579         dev_lock();
 2580         count = dev->si_usecount;
 2581         dev_unlock();
 2582         return(count);
 2583 }
 2584 
 2585 /*
 2586  * Print out a description of a vnode.
 2587  */
 2588 static char *typename[] =
 2589 {"VNON", "VREG", "VDIR", "VBLK", "VCHR", "VLNK", "VSOCK", "VFIFO", "VBAD",
 2590  "VMARKER"};
 2591 
 2592 void
 2593 vn_printf(struct vnode *vp, const char *fmt, ...)
 2594 {
 2595         va_list ap;
 2596         char buf[256], buf2[16];
 2597         u_long flags;
 2598 
 2599         va_start(ap, fmt);
 2600         vprintf(fmt, ap);
 2601         va_end(ap);
 2602         printf("%p: ", (void *)vp);
 2603         printf("tag %s, type %s\n", vp->v_tag, typename[vp->v_type]);
 2604         printf("    usecount %d, writecount %d, refcount %d mountedhere %p\n",
 2605             vp->v_usecount, vp->v_writecount, vp->v_holdcnt, vp->v_mountedhere);
 2606         buf[0] = '\0';
 2607         buf[1] = '\0';
 2608         if (vp->v_vflag & VV_ROOT)
 2609                 strlcat(buf, "|VV_ROOT", sizeof(buf));
 2610         if (vp->v_vflag & VV_ISTTY)
 2611                 strlcat(buf, "|VV_ISTTY", sizeof(buf));
 2612         if (vp->v_vflag & VV_NOSYNC)
 2613                 strlcat(buf, "|VV_NOSYNC", sizeof(buf));
 2614         if (vp->v_vflag & VV_CACHEDLABEL)
 2615                 strlcat(buf, "|VV_CACHEDLABEL", sizeof(buf));
 2616         if (vp->v_vflag & VV_TEXT)
 2617                 strlcat(buf, "|VV_TEXT", sizeof(buf));
 2618         if (vp->v_vflag & VV_COPYONWRITE)
 2619                 strlcat(buf, "|VV_COPYONWRITE", sizeof(buf));
 2620         if (vp->v_vflag & VV_SYSTEM)
 2621                 strlcat(buf, "|VV_SYSTEM", sizeof(buf));
 2622         if (vp->v_vflag & VV_PROCDEP)
 2623                 strlcat(buf, "|VV_PROCDEP", sizeof(buf));
 2624         if (vp->v_vflag & VV_NOKNOTE)
 2625                 strlcat(buf, "|VV_NOKNOTE", sizeof(buf));
 2626         if (vp->v_vflag & VV_DELETED)
 2627                 strlcat(buf, "|VV_DELETED", sizeof(buf));
 2628         if (vp->v_vflag & VV_MD)
 2629                 strlcat(buf, "|VV_MD", sizeof(buf));
 2630         flags = vp->v_vflag & ~(VV_ROOT | VV_ISTTY | VV_NOSYNC |
 2631             VV_CACHEDLABEL | VV_TEXT | VV_COPYONWRITE | VV_SYSTEM | VV_PROCDEP |
 2632             VV_NOKNOTE | VV_DELETED | VV_MD);
 2633         if (flags != 0) {
 2634                 snprintf(buf2, sizeof(buf2), "|VV(0x%lx)", flags);
 2635                 strlcat(buf, buf2, sizeof(buf));
 2636         }
 2637         if (vp->v_iflag & VI_MOUNT)
 2638                 strlcat(buf, "|VI_MOUNT", sizeof(buf));
 2639         if (vp->v_iflag & VI_AGE)
 2640                 strlcat(buf, "|VI_AGE", sizeof(buf));
 2641         if (vp->v_iflag & VI_DOOMED)
 2642                 strlcat(buf, "|VI_DOOMED", sizeof(buf));
 2643         if (vp->v_iflag & VI_FREE)
 2644                 strlcat(buf, "|VI_FREE", sizeof(buf));
 2645         if (vp->v_iflag & VI_OBJDIRTY)
 2646                 strlcat(buf, "|VI_OBJDIRTY", sizeof(buf));
 2647         if (vp->v_iflag & VI_DOINGINACT)
 2648                 strlcat(buf, "|VI_DOINGINACT", sizeof(buf));
 2649         if (vp->v_iflag & VI_OWEINACT)
 2650                 strlcat(buf, "|VI_OWEINACT", sizeof(buf));
 2651         flags = vp->v_iflag & ~(VI_MOUNT | VI_AGE | VI_DOOMED | VI_FREE |
 2652             VI_OBJDIRTY | VI_DOINGINACT | VI_OWEINACT);
 2653         if (flags != 0) {
 2654                 snprintf(buf2, sizeof(buf2), "|VI(0x%lx)", flags);
 2655                 strlcat(buf, buf2, sizeof(buf));
 2656         }
 2657         printf("    flags (%s)\n", buf + 1);
 2658         if (mtx_owned(VI_MTX(vp)))
 2659                 printf(" VI_LOCKed");
 2660         if (vp->v_object != NULL)
 2661                 printf("    v_object %p ref %d pages %d\n",
 2662                     vp->v_object, vp->v_object->ref_count,
 2663                     vp->v_object->resident_page_count);
 2664         printf("    ");
 2665         lockmgr_printinfo(vp->v_vnlock);
 2666         printf("\n");
 2667         if (vp->v_data != NULL)
 2668                 VOP_PRINT(vp);
 2669 }
 2670 
 2671 #ifdef DDB
 2672 /*
 2673  * List all of the locked vnodes in the system.
 2674  * Called when debugging the kernel.
 2675  */
 2676 DB_SHOW_COMMAND(lockedvnods, lockedvnodes)
 2677 {
 2678         struct mount *mp, *nmp;
 2679         struct vnode *vp;
 2680 
 2681         /*
 2682          * Note: because this is DDB, we can't obey the locking semantics
 2683          * for these structures, which means we could catch an inconsistent
 2684          * state and dereference a nasty pointer.  Not much to be done
 2685          * about that.
 2686          */
 2687         db_printf("Locked vnodes\n");
 2688         for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
 2689                 nmp = TAILQ_NEXT(mp, mnt_list);
 2690                 TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
 2691                         if (vp->v_type != VMARKER && VOP_ISLOCKED(vp, NULL))
 2692                                 vprint("", vp);
 2693                 }
 2694                 nmp = TAILQ_NEXT(mp, mnt_list);
 2695         }
 2696 }
 2697 
 2698 /*
 2699  * Show details about the given vnode.
 2700  */
 2701 DB_SHOW_COMMAND(vnode, db_show_vnode)
 2702 {
 2703         struct vnode *vp;
 2704 
 2705         if (!have_addr)
 2706                 return;
 2707         vp = (struct vnode *)addr;
 2708         vn_printf(vp, "vnode ");
 2709 }
 2710 #endif  /* DDB */
 2711 
 2712 /*
 2713  * Fill in a struct xvfsconf based on a struct vfsconf.
 2714  */
 2715 static void
 2716 vfsconf2x(struct vfsconf *vfsp, struct xvfsconf *xvfsp)
 2717 {
 2718 
 2719         strcpy(xvfsp->vfc_name, vfsp->vfc_name);
 2720         xvfsp->vfc_typenum = vfsp->vfc_typenum;
 2721         xvfsp->vfc_refcount = vfsp->vfc_refcount;
 2722         xvfsp->vfc_flags = vfsp->vfc_flags;
 2723         /*
 2724          * These are unused in userland, we keep them
 2725          * to not break binary compatibility.
 2726          */
 2727         xvfsp->vfc_vfsops = NULL;
 2728         xvfsp->vfc_next = NULL;
 2729 }
 2730 
 2731 /*
 2732  * Top level filesystem related information gathering.
 2733  */
 2734 static int
 2735 sysctl_vfs_conflist(SYSCTL_HANDLER_ARGS)
 2736 {
 2737         struct vfsconf *vfsp;
 2738         struct xvfsconf xvfsp;
 2739         int error;
 2740 
 2741         error = 0;
 2742         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
 2743                 bzero(&xvfsp, sizeof(xvfsp));
 2744                 vfsconf2x(vfsp, &xvfsp);
 2745                 error = SYSCTL_OUT(req, &xvfsp, sizeof xvfsp);
 2746                 if (error)
 2747                         break;
 2748         }
 2749         return (error);
 2750 }
 2751 
 2752 SYSCTL_PROC(_vfs, OID_AUTO, conflist, CTLFLAG_RD, NULL, 0, sysctl_vfs_conflist,
 2753     "S,xvfsconf", "List of all configured filesystems");
 2754 
 2755 #ifndef BURN_BRIDGES
 2756 static int      sysctl_ovfs_conf(SYSCTL_HANDLER_ARGS);
 2757 
 2758 static int
 2759 vfs_sysctl(SYSCTL_HANDLER_ARGS)
 2760 {
 2761         int *name = (int *)arg1 - 1;    /* XXX */
 2762         u_int namelen = arg2 + 1;       /* XXX */
 2763         struct vfsconf *vfsp;
 2764         struct xvfsconf xvfsp;
 2765 
 2766         printf("WARNING: userland calling deprecated sysctl, "
 2767             "please rebuild world\n");
 2768 
 2769 #if 1 || defined(COMPAT_PRELITE2)
 2770         /* Resolve ambiguity between VFS_VFSCONF and VFS_GENERIC. */
 2771         if (namelen == 1)
 2772                 return (sysctl_ovfs_conf(oidp, arg1, arg2, req));
 2773 #endif
 2774 
 2775         switch (name[1]) {
 2776         case VFS_MAXTYPENUM:
 2777                 if (namelen != 2)
 2778                         return (ENOTDIR);
 2779                 return (SYSCTL_OUT(req, &maxvfsconf, sizeof(int)));
 2780         case VFS_CONF:
 2781                 if (namelen != 3)
 2782                         return (ENOTDIR);       /* overloaded */
 2783                 TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
 2784                         if (vfsp->vfc_typenum == name[2])
 2785                                 break;
 2786                 if (vfsp == NULL)
 2787                         return (EOPNOTSUPP);
 2788                 bzero(&xvfsp, sizeof(xvfsp));
 2789                 vfsconf2x(vfsp, &xvfsp);
 2790                 return (SYSCTL_OUT(req, &xvfsp, sizeof(xvfsp)));
 2791         }
 2792         return (EOPNOTSUPP);
 2793 }
 2794 
 2795 static SYSCTL_NODE(_vfs, VFS_GENERIC, generic, CTLFLAG_RD | CTLFLAG_SKIP,
 2796         vfs_sysctl, "Generic filesystem");
 2797 
 2798 #if 1 || defined(COMPAT_PRELITE2)
 2799 
 2800 static int
 2801 sysctl_ovfs_conf(SYSCTL_HANDLER_ARGS)
 2802 {
 2803         int error;
 2804         struct vfsconf *vfsp;
 2805         struct ovfsconf ovfs;
 2806 
 2807         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
 2808                 bzero(&ovfs, sizeof(ovfs));
 2809                 ovfs.vfc_vfsops = vfsp->vfc_vfsops;     /* XXX used as flag */
 2810                 strcpy(ovfs.vfc_name, vfsp->vfc_name);
 2811                 ovfs.vfc_index = vfsp->vfc_typenum;
 2812                 ovfs.vfc_refcount = vfsp->vfc_refcount;
 2813                 ovfs.vfc_flags = vfsp->vfc_flags;
 2814                 error = SYSCTL_OUT(req, &ovfs, sizeof ovfs);
 2815                 if (error)
 2816                         return error;
 2817         }
 2818         return 0;
 2819 }
 2820 
 2821 #endif /* 1 || COMPAT_PRELITE2 */
 2822 #endif /* !BURN_BRIDGES */
 2823 
 2824 #define KINFO_VNODESLOP         10
 2825 #ifdef notyet
 2826 /*
 2827  * Dump vnode list (via sysctl).
 2828  */
 2829 /* ARGSUSED */
 2830 static int
 2831 sysctl_vnode(SYSCTL_HANDLER_ARGS)
 2832 {
 2833         struct xvnode *xvn;
 2834         struct thread *td = req->td;
 2835         struct mount *mp;
 2836         struct vnode *vp;
 2837         int error, len, n;
 2838 
 2839         /*
 2840          * Stale numvnodes access is not fatal here.
 2841          */
 2842         req->lock = 0;
 2843         len = (numvnodes + KINFO_VNODESLOP) * sizeof *xvn;
 2844         if (!req->oldptr)
 2845                 /* Make an estimate */
 2846                 return (SYSCTL_OUT(req, 0, len));
 2847 
 2848         error = sysctl_wire_old_buffer(req, 0);
 2849         if (error != 0)
 2850                 return (error);
 2851         xvn = malloc(len, M_TEMP, M_ZERO | M_WAITOK);
 2852         n = 0;
 2853         mtx_lock(&mountlist_mtx);
 2854         TAILQ_FOREACH(mp, &mountlist, mnt_list) {
 2855                 if (vfs_busy(mp, LK_NOWAIT, &mountlist_mtx, td))
 2856                         continue;
 2857                 MNT_ILOCK(mp);
 2858                 TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
 2859                         if (n == len)
 2860                                 break;
 2861                         vref(vp);
 2862                         xvn[n].xv_size = sizeof *xvn;
 2863                         xvn[n].xv_vnode = vp;
 2864                         xvn[n].xv_id = 0;       /* XXX compat */
 2865 #define XV_COPY(field) xvn[n].xv_##field = vp->v_##field
 2866                         XV_COPY(usecount);
 2867                         XV_COPY(writecount);
 2868                         XV_COPY(holdcnt);
 2869                         XV_COPY(mount);
 2870                         XV_COPY(numoutput);
 2871                         XV_COPY(type);
 2872 #undef XV_COPY
 2873                         xvn[n].xv_flag = vp->v_vflag;
 2874 
 2875                         switch (vp->v_type) {
 2876                         case VREG:
 2877                         case VDIR:
 2878                         case VLNK:
 2879                                 break;
 2880                         case VBLK:
 2881                         case VCHR:
 2882                                 if (vp->v_rdev == NULL) {
 2883                                         vrele(vp);
 2884                                         continue;
 2885                                 }
 2886                                 xvn[n].xv_dev = dev2udev(vp->v_rdev);
 2887                                 break;
 2888                         case VSOCK:
 2889                                 xvn[n].xv_socket = vp->v_socket;
 2890                                 break;
 2891                         case VFIFO:
 2892                                 xvn[n].xv_fifo = vp->v_fifoinfo;
 2893                                 break;
 2894                         case VNON:
 2895                         case VBAD:
 2896                         default:
 2897                                 /* shouldn't happen? */
 2898                                 vrele(vp);
 2899                                 continue;
 2900                         }
 2901                         vrele(vp);
 2902                         ++n;
 2903                 }
 2904                 MNT_IUNLOCK(mp);
 2905                 mtx_lock(&mountlist_mtx);
 2906                 vfs_unbusy(mp, td);
 2907                 if (n == len)
 2908                         break;
 2909         }
 2910         mtx_unlock(&mountlist_mtx);
 2911 
 2912         error = SYSCTL_OUT(req, xvn, n * sizeof *xvn);
 2913         free(xvn, M_TEMP);
 2914         return (error);
 2915 }
 2916 
 2917 SYSCTL_PROC(_kern, KERN_VNODE, vnode, CTLTYPE_OPAQUE|CTLFLAG_RD,
 2918         0, 0, sysctl_vnode, "S,xvnode", "");
 2919 #endif
 2920 
 2921 /*
 2922  * Unmount all filesystems. The list is traversed in reverse order
 2923  * of mounting to avoid dependencies.
 2924  */
 2925 void
 2926 vfs_unmountall(void)
 2927 {
 2928         struct mount *mp;
 2929         struct thread *td;
 2930         int error;
 2931 
 2932         KASSERT(curthread != NULL, ("vfs_unmountall: NULL curthread"));
 2933         td = curthread;
 2934         /*
 2935          * Since this only runs when rebooting, it is not interlocked.
 2936          */
 2937         while(!TAILQ_EMPTY(&mountlist)) {
 2938                 mp = TAILQ_LAST(&mountlist, mntlist);
 2939                 error = dounmount(mp, MNT_FORCE, td);
 2940                 if (error) {
 2941                         TAILQ_REMOVE(&mountlist, mp, mnt_list);
 2942                         /*
 2943                          * XXX: Due to the way in which we mount the root
 2944                          * file system off of devfs, devfs will generate a
 2945                          * "busy" warning when we try to unmount it before
 2946                          * the root.  Don't print a warning as a result in
 2947                          * order to avoid false positive errors that may
 2948                          * cause needless upset.
 2949                          */
 2950                         if (strcmp(mp->mnt_vfc->vfc_name, "devfs") != 0) {
 2951                                 printf("unmount of %s failed (",
 2952                                     mp->mnt_stat.f_mntonname);
 2953                                 if (error == EBUSY)
 2954                                         printf("BUSY)\n");
 2955                                 else
 2956                                         printf("%d)\n", error);
 2957                         }
 2958                 } else {
 2959                         /* The unmount has removed mp from the mountlist */
 2960                 }
 2961         }
 2962 }
 2963 
 2964 /*
 2965  * perform msync on all vnodes under a mount point
 2966  * the mount point must be locked.
 2967  */
 2968 void
 2969 vfs_msync(struct mount *mp, int flags)
 2970 {
 2971         struct vnode *vp, *mvp;
 2972         struct vm_object *obj;
 2973 
 2974         MNT_ILOCK(mp);
 2975         MNT_VNODE_FOREACH(vp, mp, mvp) {
 2976                 VI_LOCK(vp);
 2977                 if ((vp->v_iflag & VI_OBJDIRTY) &&
 2978                     (flags == MNT_WAIT || VOP_ISLOCKED(vp, NULL) == 0)) {
 2979                         MNT_IUNLOCK(mp);
 2980                         if (!vget(vp,
 2981                             LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK,
 2982                             curthread)) {
 2983                                 if (vp->v_vflag & VV_NOSYNC) {  /* unlinked */
 2984                                         vput(vp);
 2985                                         MNT_ILOCK(mp);
 2986                                         continue;
 2987                                 }
 2988 
 2989                                 obj = vp->v_object;
 2990                                 if (obj != NULL) {
 2991                                         VM_OBJECT_LOCK(obj);
 2992                                         vm_object_page_clean(obj, 0, 0,
 2993                                             flags == MNT_WAIT ?
 2994                                             OBJPC_SYNC : OBJPC_NOSYNC);
 2995                                         VM_OBJECT_UNLOCK(obj);
 2996                                 }
 2997                                 vput(vp);
 2998                         }
 2999                         MNT_ILOCK(mp);
 3000                 } else
 3001                         VI_UNLOCK(vp);
 3002         }
 3003         MNT_IUNLOCK(mp);
 3004 }
 3005 
 3006 /*
 3007  * Mark a vnode as free, putting it up for recycling.
 3008  */
 3009 static void
 3010 vfree(struct vnode *vp)
 3011 {
 3012 
 3013         CTR1(KTR_VFS, "vfree vp %p", vp);
 3014         ASSERT_VI_LOCKED(vp, "vfree");
 3015         mtx_lock(&vnode_free_list_mtx);
 3016         VNASSERT(vp->v_op != NULL, vp, ("vfree: vnode already reclaimed."));
 3017         VNASSERT((vp->v_iflag & VI_FREE) == 0, vp, ("vnode already free"));
 3018         VNASSERT(VSHOULDFREE(vp), vp, ("vfree: freeing when we shouldn't"));
 3019         VNASSERT((vp->v_iflag & VI_DOOMED) == 0, vp,
 3020             ("vfree: Freeing doomed vnode"));
 3021         if (vp->v_iflag & VI_AGE) {
 3022                 TAILQ_INSERT_HEAD(&vnode_free_list, vp, v_freelist);
 3023         } else {
 3024                 TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
 3025         }
 3026         freevnodes++;
 3027         vp->v_iflag &= ~VI_AGE;
 3028         vp->v_iflag |= VI_FREE;
 3029         mtx_unlock(&vnode_free_list_mtx);
 3030 }
 3031 
 3032 /*
 3033  * Opposite of vfree() - mark a vnode as in use.
 3034  */
 3035 static void
 3036 vbusy(struct vnode *vp)
 3037 {
 3038         CTR1(KTR_VFS, "vbusy vp %p", vp);
 3039         ASSERT_VI_LOCKED(vp, "vbusy");
 3040         VNASSERT((vp->v_iflag & VI_FREE) != 0, vp, ("vnode not free"));
 3041         VNASSERT(vp->v_op != NULL, vp, ("vbusy: vnode already reclaimed."));
 3042 
 3043         mtx_lock(&vnode_free_list_mtx);
 3044         TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
 3045         freevnodes--;
 3046         vp->v_iflag &= ~(VI_FREE|VI_AGE);
 3047         mtx_unlock(&vnode_free_list_mtx);
 3048 }
 3049 
 3050 static void
 3051 destroy_vpollinfo(struct vpollinfo *vi)
 3052 {
 3053         knlist_destroy(&vi->vpi_selinfo.si_note);
 3054         mtx_destroy(&vi->vpi_lock);
 3055         uma_zfree(vnodepoll_zone, vi);
 3056 }
 3057 
 3058 /*
 3059  * Initalize per-vnode helper structure to hold poll-related state.
 3060  */
 3061 void
 3062 v_addpollinfo(struct vnode *vp)
 3063 {
 3064         struct vpollinfo *vi;
 3065 
 3066         if (vp->v_pollinfo != NULL)
 3067                 return;
 3068         vi = uma_zalloc(vnodepoll_zone, M_WAITOK);
 3069         mtx_init(&vi->vpi_lock, "vnode pollinfo", NULL, MTX_DEF);
 3070         knlist_init(&vi->vpi_selinfo.si_note, vp, vfs_knllock,
 3071             vfs_knlunlock, vfs_knllocked);
 3072         VI_LOCK(vp);
 3073         if (vp->v_pollinfo != NULL) {
 3074                 VI_UNLOCK(vp);
 3075                 destroy_vpollinfo(vi);
 3076                 return;
 3077         }
 3078         vp->v_pollinfo = vi;
 3079         VI_UNLOCK(vp);
 3080 }
 3081 
 3082 /*
 3083  * Record a process's interest in events which might happen to
 3084  * a vnode.  Because poll uses the historic select-style interface
 3085  * internally, this routine serves as both the ``check for any
 3086  * pending events'' and the ``record my interest in future events''
 3087  * functions.  (These are done together, while the lock is held,
 3088  * to avoid race conditions.)
 3089  */
 3090 int
 3091 vn_pollrecord(struct vnode *vp, struct thread *td, int events)
 3092 {
 3093 
 3094         v_addpollinfo(vp);
 3095         mtx_lock(&vp->v_pollinfo->vpi_lock);
 3096         if (vp->v_pollinfo->vpi_revents & events) {
 3097                 /*
 3098                  * This leaves events we are not interested
 3099                  * in available for the other process which
 3100                  * which presumably had requested them
 3101                  * (otherwise they would never have been
 3102                  * recorded).
 3103                  */
 3104                 events &= vp->v_pollinfo->vpi_revents;
 3105                 vp->v_pollinfo->vpi_revents &= ~events;
 3106 
 3107                 mtx_unlock(&vp->v_pollinfo->vpi_lock);
 3108                 return events;
 3109         }
 3110         vp->v_pollinfo->vpi_events |= events;
 3111         selrecord(td, &vp->v_pollinfo->vpi_selinfo);
 3112         mtx_unlock(&vp->v_pollinfo->vpi_lock);
 3113         return 0;
 3114 }
 3115 
 3116 /*
 3117  * Routine to create and manage a filesystem syncer vnode.
 3118  */
 3119 #define sync_close ((int (*)(struct  vop_close_args *))nullop)
 3120 static int      sync_fsync(struct  vop_fsync_args *);
 3121 static int      sync_inactive(struct  vop_inactive_args *);
 3122 static int      sync_reclaim(struct  vop_reclaim_args *);
 3123 
 3124 static struct vop_vector sync_vnodeops = {
 3125         .vop_bypass =   VOP_EOPNOTSUPP,
 3126         .vop_close =    sync_close,             /* close */
 3127         .vop_fsync =    sync_fsync,             /* fsync */
 3128         .vop_inactive = sync_inactive,  /* inactive */
 3129         .vop_reclaim =  sync_reclaim,   /* reclaim */
 3130         .vop_lock1 =    vop_stdlock,    /* lock */
 3131         .vop_unlock =   vop_stdunlock,  /* unlock */
 3132         .vop_islocked = vop_stdislocked,        /* islocked */
 3133 };
 3134 
 3135 /*
 3136  * Create a new filesystem syncer vnode for the specified mount point.
 3137  */
 3138 int
 3139 vfs_allocate_syncvnode(struct mount *mp)
 3140 {
 3141         struct vnode *vp;
 3142         static long start, incr, next;
 3143         int error;
 3144 
 3145         /* Allocate a new vnode */
 3146         if ((error = getnewvnode("syncer", mp, &sync_vnodeops, &vp)) != 0) {
 3147                 mp->mnt_syncer = NULL;
 3148                 return (error);
 3149         }
 3150         vp->v_type = VNON;
 3151         error = insmntque(vp, mp);
 3152         if (error != 0)
 3153                 panic("vfs_allocate_syncvnode: insmntque failed");
 3154         /*
 3155          * Place the vnode onto the syncer worklist. We attempt to
 3156          * scatter them about on the list so that they will go off
 3157          * at evenly distributed times even if all the filesystems
 3158          * are mounted at once.
 3159          */
 3160         next += incr;
 3161         if (next == 0 || next > syncer_maxdelay) {
 3162                 start /= 2;
 3163                 incr /= 2;
 3164                 if (start == 0) {
 3165                         start = syncer_maxdelay / 2;
 3166                         incr = syncer_maxdelay;
 3167                 }
 3168                 next = start;
 3169         }
 3170         VI_LOCK(vp);
 3171         vn_syncer_add_to_worklist(&vp->v_bufobj,
 3172             syncdelay > 0 ? next % syncdelay : 0);
 3173         /* XXX - vn_syncer_add_to_worklist() also grabs and drops sync_mtx. */
 3174         mtx_lock(&sync_mtx);
 3175         sync_vnode_count++;
 3176         mtx_unlock(&sync_mtx);
 3177         VI_UNLOCK(vp);
 3178         mp->mnt_syncer = vp;
 3179         return (0);
 3180 }
 3181 
 3182 /*
 3183  * Do a lazy sync of the filesystem.
 3184  */
 3185 static int
 3186 sync_fsync(struct vop_fsync_args *ap)
 3187 {
 3188         struct vnode *syncvp = ap->a_vp;
 3189         struct mount *mp = syncvp->v_mount;
 3190         struct thread *td = ap->a_td;
 3191         int error;
 3192         struct bufobj *bo;
 3193 
 3194         /*
 3195          * We only need to do something if this is a lazy evaluation.
 3196          */
 3197         if (ap->a_waitfor != MNT_LAZY)
 3198                 return (0);
 3199 
 3200         /*
 3201          * Move ourselves to the back of the sync list.
 3202          */
 3203         bo = &syncvp->v_bufobj;
 3204         BO_LOCK(bo);
 3205         vn_syncer_add_to_worklist(bo, syncdelay);
 3206         BO_UNLOCK(bo);
 3207 
 3208         /*
 3209          * Walk the list of vnodes pushing all that are dirty and
 3210          * not already on the sync list.
 3211          */
 3212         mtx_lock(&mountlist_mtx);
 3213         if (vfs_busy(mp, LK_EXCLUSIVE | LK_NOWAIT, &mountlist_mtx, td) != 0) {
 3214                 mtx_unlock(&mountlist_mtx);
 3215                 return (0);
 3216         }
 3217         if (vn_start_write(NULL, &mp, V_NOWAIT) != 0) {
 3218                 vfs_unbusy(mp, td);
 3219                 return (0);
 3220         }
 3221         MNT_ILOCK(mp);
 3222         mp->mnt_noasync++;
 3223         mp->mnt_kern_flag &= ~MNTK_ASYNC;
 3224         MNT_IUNLOCK(mp);
 3225         vfs_msync(mp, MNT_NOWAIT);
 3226         error = VFS_SYNC(mp, MNT_LAZY, td);
 3227         MNT_ILOCK(mp);
 3228         mp->mnt_noasync--;
 3229         if ((mp->mnt_flag & MNT_ASYNC) != 0 && mp->mnt_noasync == 0)
 3230                 mp->mnt_kern_flag |= MNTK_ASYNC;
 3231         MNT_IUNLOCK(mp);
 3232         vn_finished_write(mp);
 3233         vfs_unbusy(mp, td);
 3234         return (error);
 3235 }
 3236 
 3237 /*
 3238  * The syncer vnode is no referenced.
 3239  */
 3240 static int
 3241 sync_inactive(struct vop_inactive_args *ap)
 3242 {
 3243 
 3244         vgone(ap->a_vp);
 3245         return (0);
 3246 }
 3247 
 3248 /*
 3249  * The syncer vnode is no longer needed and is being decommissioned.
 3250  *
 3251  * Modifications to the worklist must be protected by sync_mtx.
 3252  */
 3253 static int
 3254 sync_reclaim(struct vop_reclaim_args *ap)
 3255 {
 3256         struct vnode *vp = ap->a_vp;
 3257         struct bufobj *bo;
 3258 
 3259         VI_LOCK(vp);
 3260         bo = &vp->v_bufobj;
 3261         vp->v_mount->mnt_syncer = NULL;
 3262         if (bo->bo_flag & BO_ONWORKLST) {
 3263                 mtx_lock(&sync_mtx);
 3264                 LIST_REMOVE(bo, bo_synclist);
 3265                 syncer_worklist_len--;
 3266                 sync_vnode_count--;
 3267                 mtx_unlock(&sync_mtx);
 3268                 bo->bo_flag &= ~BO_ONWORKLST;
 3269         }
 3270         VI_UNLOCK(vp);
 3271 
 3272         return (0);
 3273 }
 3274 
 3275 /*
 3276  * Check if vnode represents a disk device
 3277  */
 3278 int
 3279 vn_isdisk(struct vnode *vp, int *errp)
 3280 {
 3281         int error;
 3282 
 3283         error = 0;
 3284         dev_lock();
 3285         if (vp->v_type != VCHR)
 3286                 error = ENOTBLK;
 3287         else if (vp->v_rdev == NULL)
 3288                 error = ENXIO;
 3289         else if (vp->v_rdev->si_devsw == NULL)
 3290                 error = ENXIO;
 3291         else if (!(vp->v_rdev->si_devsw->d_flags & D_DISK))
 3292                 error = ENOTBLK;
 3293         dev_unlock();
 3294         if (errp != NULL)
 3295                 *errp = error;
 3296         return (error == 0);
 3297 }
 3298 
 3299 /*
 3300  * Common filesystem object access control check routine.  Accepts a
 3301  * vnode's type, "mode", uid and gid, requested access mode, credentials,
 3302  * and optional call-by-reference privused argument allowing vaccess()
 3303  * to indicate to the caller whether privilege was used to satisfy the
 3304  * request (obsoleted).  Returns 0 on success, or an errno on failure.
 3305  *
 3306  * The ifdef'd CAPABILITIES version is here for reference, but is not
 3307  * actually used.
 3308  */
 3309 int
 3310 vaccess(enum vtype type, mode_t file_mode, uid_t file_uid, gid_t file_gid,
 3311     mode_t acc_mode, struct ucred *cred, int *privused)
 3312 {
 3313         mode_t dac_granted;
 3314         mode_t priv_granted;
 3315 
 3316         /*
 3317          * Look for a normal, non-privileged way to access the file/directory
 3318          * as requested.  If it exists, go with that.
 3319          */
 3320 
 3321         if (privused != NULL)
 3322                 *privused = 0;
 3323 
 3324         dac_granted = 0;
 3325 
 3326         /* Check the owner. */
 3327         if (cred->cr_uid == file_uid) {
 3328                 dac_granted |= VADMIN;
 3329                 if (file_mode & S_IXUSR)
 3330                         dac_granted |= VEXEC;
 3331                 if (file_mode & S_IRUSR)
 3332                         dac_granted |= VREAD;
 3333                 if (file_mode & S_IWUSR)
 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 the groups (first match) */
 3343         if (groupmember(file_gid, cred)) {
 3344                 if (file_mode & S_IXGRP)
 3345                         dac_granted |= VEXEC;
 3346                 if (file_mode & S_IRGRP)
 3347                         dac_granted |= VREAD;
 3348                 if (file_mode & S_IWGRP)
 3349                         dac_granted |= (VWRITE | VAPPEND);
 3350 
 3351                 if ((acc_mode & dac_granted) == acc_mode)
 3352                         return (0);
 3353 
 3354                 goto privcheck;
 3355         }
 3356 
 3357         /* Otherwise, check everyone else. */
 3358         if (file_mode & S_IXOTH)
 3359                 dac_granted |= VEXEC;
 3360         if (file_mode & S_IROTH)
 3361                 dac_granted |= VREAD;
 3362         if (file_mode & S_IWOTH)
 3363                 dac_granted |= (VWRITE | VAPPEND);
 3364         if ((acc_mode & dac_granted) == acc_mode)
 3365                 return (0);
 3366 
 3367 privcheck:
 3368         /*
 3369          * Build a privilege mask to determine if the set of privileges
 3370          * satisfies the requirements when combined with the granted mask
 3371          * from above.  For each privilege, if the privilege is required,
 3372          * bitwise or the request type onto the priv_granted mask.
 3373          */
 3374         priv_granted = 0;
 3375 
 3376         if (type == VDIR) {
 3377                 /*
 3378                  * For directories, use PRIV_VFS_LOOKUP to satisfy VEXEC
 3379                  * requests, instead of PRIV_VFS_EXEC.
 3380                  */
 3381                 if ((acc_mode & VEXEC) && ((dac_granted & VEXEC) == 0) &&
 3382                     !priv_check_cred(cred, PRIV_VFS_LOOKUP, 0))
 3383                         priv_granted |= VEXEC;
 3384         } else {
 3385                 if ((acc_mode & VEXEC) && ((dac_granted & VEXEC) == 0) &&
 3386                     !priv_check_cred(cred, PRIV_VFS_EXEC, 0))
 3387                         priv_granted |= VEXEC;
 3388         }
 3389 
 3390         if ((acc_mode & VREAD) && ((dac_granted & VREAD) == 0) &&
 3391             !priv_check_cred(cred, PRIV_VFS_READ, 0))
 3392                 priv_granted |= VREAD;
 3393 
 3394         if ((acc_mode & VWRITE) && ((dac_granted & VWRITE) == 0) &&
 3395             !priv_check_cred(cred, PRIV_VFS_WRITE, 0))
 3396                 priv_granted |= (VWRITE | VAPPEND);
 3397 
 3398         if ((acc_mode & VADMIN) && ((dac_granted & VADMIN) == 0) &&
 3399             !priv_check_cred(cred, PRIV_VFS_ADMIN, 0))
 3400                 priv_granted |= VADMIN;
 3401 
 3402         if ((acc_mode & (priv_granted | dac_granted)) == acc_mode) {
 3403                 /* XXX audit: privilege used */
 3404                 if (privused != NULL)
 3405                         *privused = 1;
 3406                 return (0);
 3407         }
 3408 
 3409         return ((acc_mode & VADMIN) ? EPERM : EACCES);
 3410 }
 3411 
 3412 /*
 3413  * Credential check based on process requesting service, and per-attribute
 3414  * permissions.
 3415  */
 3416 int
 3417 extattr_check_cred(struct vnode *vp, int attrnamespace, struct ucred *cred,
 3418     struct thread *td, int access)
 3419 {
 3420 
 3421         /*
 3422          * Kernel-invoked always succeeds.
 3423          */
 3424         if (cred == NOCRED)
 3425                 return (0);
 3426 
 3427         /*
 3428          * Do not allow privileged processes in jail to directly manipulate
 3429          * system attributes.
 3430          */
 3431         switch (attrnamespace) {
 3432         case EXTATTR_NAMESPACE_SYSTEM:
 3433                 /* Potentially should be: return (EPERM); */
 3434                 return (priv_check_cred(cred, PRIV_VFS_EXTATTR_SYSTEM, 0));
 3435         case EXTATTR_NAMESPACE_USER:
 3436                 return (VOP_ACCESS(vp, access, cred, td));
 3437         default:
 3438                 return (EPERM);
 3439         }
 3440 }
 3441 
 3442 #ifdef DEBUG_VFS_LOCKS
 3443 /*
 3444  * This only exists to supress warnings from unlocked specfs accesses.  It is
 3445  * no longer ok to have an unlocked VFS.
 3446  */
 3447 #define IGNORE_LOCK(vp) ((vp)->v_type == VCHR || (vp)->v_type == VBAD)
 3448 
 3449 int vfs_badlock_ddb = 1;        /* Drop into debugger on violation. */
 3450 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_ddb, CTLFLAG_RW, &vfs_badlock_ddb, 0, "");
 3451 
 3452 int vfs_badlock_mutex = 1;      /* Check for interlock across VOPs. */
 3453 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_mutex, CTLFLAG_RW, &vfs_badlock_mutex, 0, "");
 3454 
 3455 int vfs_badlock_print = 1;      /* Print lock violations. */
 3456 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_print, CTLFLAG_RW, &vfs_badlock_print, 0, "");
 3457 
 3458 #ifdef KDB
 3459 int vfs_badlock_backtrace = 1;  /* Print backtrace at lock violations. */
 3460 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_backtrace, CTLFLAG_RW, &vfs_badlock_backtrace, 0, "");
 3461 #endif
 3462 
 3463 static void
 3464 vfs_badlock(const char *msg, const char *str, struct vnode *vp)
 3465 {
 3466 
 3467 #ifdef KDB
 3468         if (vfs_badlock_backtrace)
 3469                 kdb_backtrace();
 3470 #endif
 3471         if (vfs_badlock_print)
 3472                 printf("%s: %p %s\n", str, (void *)vp, msg);
 3473         if (vfs_badlock_ddb)
 3474                 kdb_enter_why(KDB_WHY_VFSLOCK, "lock violation");
 3475 }
 3476 
 3477 void
 3478 assert_vi_locked(struct vnode *vp, const char *str)
 3479 {
 3480 
 3481         if (vfs_badlock_mutex && !mtx_owned(VI_MTX(vp)))
 3482                 vfs_badlock("interlock is not locked but should be", str, vp);
 3483 }
 3484 
 3485 void
 3486 assert_vi_unlocked(struct vnode *vp, const char *str)
 3487 {
 3488 
 3489         if (vfs_badlock_mutex && mtx_owned(VI_MTX(vp)))
 3490                 vfs_badlock("interlock is locked but should not be", str, vp);
 3491 }
 3492 
 3493 void
 3494 assert_vop_locked(struct vnode *vp, const char *str)
 3495 {
 3496 
 3497         if (vp && !IGNORE_LOCK(vp) && VOP_ISLOCKED(vp, NULL) == 0)
 3498                 vfs_badlock("is not locked but should be", str, vp);
 3499 }
 3500 
 3501 void
 3502 assert_vop_unlocked(struct vnode *vp, const char *str)
 3503 {
 3504 
 3505         if (vp && !IGNORE_LOCK(vp) &&
 3506             VOP_ISLOCKED(vp, curthread) == LK_EXCLUSIVE)
 3507                 vfs_badlock("is locked but should not be", str, vp);
 3508 }
 3509 
 3510 void
 3511 assert_vop_elocked(struct vnode *vp, const char *str)
 3512 {
 3513 
 3514         if (vp && !IGNORE_LOCK(vp) &&
 3515             VOP_ISLOCKED(vp, curthread) != LK_EXCLUSIVE)
 3516                 vfs_badlock("is not exclusive locked but should be", str, vp);
 3517 }
 3518 
 3519 #if 0
 3520 void
 3521 assert_vop_elocked_other(struct vnode *vp, const char *str)
 3522 {
 3523 
 3524         if (vp && !IGNORE_LOCK(vp) &&
 3525             VOP_ISLOCKED(vp, curthread) != LK_EXCLOTHER)
 3526                 vfs_badlock("is not exclusive locked by another thread",
 3527                     str, vp);
 3528 }
 3529 
 3530 void
 3531 assert_vop_slocked(struct vnode *vp, const char *str)
 3532 {
 3533 
 3534         if (vp && !IGNORE_LOCK(vp) &&
 3535             VOP_ISLOCKED(vp, curthread) != LK_SHARED)
 3536                 vfs_badlock("is not locked shared but should be", str, vp);
 3537 }
 3538 #endif /* 0 */
 3539 #endif /* DEBUG_VFS_LOCKS */
 3540 
 3541 void
 3542 vop_rename_pre(void *ap)
 3543 {
 3544         struct vop_rename_args *a = ap;
 3545 
 3546 #ifdef DEBUG_VFS_LOCKS
 3547         if (a->a_tvp)
 3548                 ASSERT_VI_UNLOCKED(a->a_tvp, "VOP_RENAME");
 3549         ASSERT_VI_UNLOCKED(a->a_tdvp, "VOP_RENAME");
 3550         ASSERT_VI_UNLOCKED(a->a_fvp, "VOP_RENAME");
 3551         ASSERT_VI_UNLOCKED(a->a_fdvp, "VOP_RENAME");
 3552 
 3553         /* Check the source (from). */
 3554         if (a->a_tdvp != a->a_fdvp && a->a_tvp != a->a_fdvp)
 3555                 ASSERT_VOP_UNLOCKED(a->a_fdvp, "vop_rename: fdvp locked");
 3556         if (a->a_tvp != a->a_fvp)
 3557                 ASSERT_VOP_UNLOCKED(a->a_fvp, "vop_rename: fvp locked");
 3558 
 3559         /* Check the target. */
 3560         if (a->a_tvp)
 3561                 ASSERT_VOP_LOCKED(a->a_tvp, "vop_rename: tvp not locked");
 3562         ASSERT_VOP_LOCKED(a->a_tdvp, "vop_rename: tdvp not locked");
 3563 #endif
 3564         if (a->a_tdvp != a->a_fdvp)
 3565                 vhold(a->a_fdvp);
 3566         if (a->a_tvp != a->a_fvp)
 3567                 vhold(a->a_fvp);
 3568         vhold(a->a_tdvp);
 3569         if (a->a_tvp)
 3570                 vhold(a->a_tvp);
 3571 }
 3572 
 3573 void
 3574 vop_strategy_pre(void *ap)
 3575 {
 3576 #ifdef DEBUG_VFS_LOCKS
 3577         struct vop_strategy_args *a;
 3578         struct buf *bp;
 3579 
 3580         a = ap;
 3581         bp = a->a_bp;
 3582 
 3583         /*
 3584          * Cluster ops lock their component buffers but not the IO container.
 3585          */
 3586         if ((bp->b_flags & B_CLUSTER) != 0)
 3587                 return;
 3588 
 3589         if (BUF_REFCNT(bp) < 1) {
 3590                 if (vfs_badlock_print)
 3591                         printf(
 3592                             "VOP_STRATEGY: bp is not locked but should be\n");
 3593                 if (vfs_badlock_ddb)
 3594                         kdb_enter_why(KDB_WHY_VFSLOCK, "lock violation");
 3595         }
 3596 #endif
 3597 }
 3598 
 3599 void
 3600 vop_lookup_pre(void *ap)
 3601 {
 3602 #ifdef DEBUG_VFS_LOCKS
 3603         struct vop_lookup_args *a;
 3604         struct vnode *dvp;
 3605 
 3606         a = ap;
 3607         dvp = a->a_dvp;
 3608         ASSERT_VI_UNLOCKED(dvp, "VOP_LOOKUP");
 3609         ASSERT_VOP_LOCKED(dvp, "VOP_LOOKUP");
 3610 #endif
 3611 }
 3612 
 3613 void
 3614 vop_lookup_post(void *ap, int rc)
 3615 {
 3616 #ifdef DEBUG_VFS_LOCKS
 3617         struct vop_lookup_args *a;
 3618         struct vnode *dvp;
 3619         struct vnode *vp;
 3620 
 3621         a = ap;
 3622         dvp = a->a_dvp;
 3623         vp = *(a->a_vpp);
 3624 
 3625         ASSERT_VI_UNLOCKED(dvp, "VOP_LOOKUP");
 3626         ASSERT_VOP_LOCKED(dvp, "VOP_LOOKUP");
 3627 
 3628         if (!rc)
 3629                 ASSERT_VOP_LOCKED(vp, "VOP_LOOKUP (child)");
 3630 #endif
 3631 }
 3632 
 3633 void
 3634 vop_lock_pre(void *ap)
 3635 {
 3636 #ifdef DEBUG_VFS_LOCKS
 3637         struct vop_lock1_args *a = ap;
 3638 
 3639         if ((a->a_flags & LK_INTERLOCK) == 0)
 3640                 ASSERT_VI_UNLOCKED(a->a_vp, "VOP_LOCK");
 3641         else
 3642                 ASSERT_VI_LOCKED(a->a_vp, "VOP_LOCK");
 3643 #endif
 3644 }
 3645 
 3646 void
 3647 vop_lock_post(void *ap, int rc)
 3648 {
 3649 #ifdef DEBUG_VFS_LOCKS
 3650         struct vop_lock1_args *a = ap;
 3651 
 3652         ASSERT_VI_UNLOCKED(a->a_vp, "VOP_LOCK");
 3653         if (rc == 0)
 3654                 ASSERT_VOP_LOCKED(a->a_vp, "VOP_LOCK");
 3655 #endif
 3656 }
 3657 
 3658 void
 3659 vop_unlock_pre(void *ap)
 3660 {
 3661 #ifdef DEBUG_VFS_LOCKS
 3662         struct vop_unlock_args *a = ap;
 3663 
 3664         if (a->a_flags & LK_INTERLOCK)
 3665                 ASSERT_VI_LOCKED(a->a_vp, "VOP_UNLOCK");
 3666         ASSERT_VOP_LOCKED(a->a_vp, "VOP_UNLOCK");
 3667 #endif
 3668 }
 3669 
 3670 void
 3671 vop_unlock_post(void *ap, int rc)
 3672 {
 3673 #ifdef DEBUG_VFS_LOCKS
 3674         struct vop_unlock_args *a = ap;
 3675 
 3676         if (a->a_flags & LK_INTERLOCK)
 3677                 ASSERT_VI_UNLOCKED(a->a_vp, "VOP_UNLOCK");
 3678 #endif
 3679 }
 3680 
 3681 void
 3682 vop_create_post(void *ap, int rc)
 3683 {
 3684         struct vop_create_args *a = ap;
 3685 
 3686         if (!rc)
 3687                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 3688 }
 3689 
 3690 void
 3691 vop_link_post(void *ap, int rc)
 3692 {
 3693         struct vop_link_args *a = ap;
 3694 
 3695         if (!rc) {
 3696                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_LINK);
 3697                 VFS_KNOTE_LOCKED(a->a_tdvp, NOTE_WRITE);
 3698         }
 3699 }
 3700 
 3701 void
 3702 vop_mkdir_post(void *ap, int rc)
 3703 {
 3704         struct vop_mkdir_args *a = ap;
 3705 
 3706         if (!rc)
 3707                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE | NOTE_LINK);
 3708 }
 3709 
 3710 void
 3711 vop_mknod_post(void *ap, int rc)
 3712 {
 3713         struct vop_mknod_args *a = ap;
 3714 
 3715         if (!rc)
 3716                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 3717 }
 3718 
 3719 void
 3720 vop_remove_post(void *ap, int rc)
 3721 {
 3722         struct vop_remove_args *a = ap;
 3723 
 3724         if (!rc) {
 3725                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 3726                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_DELETE);
 3727         }
 3728 }
 3729 
 3730 void
 3731 vop_rename_post(void *ap, int rc)
 3732 {
 3733         struct vop_rename_args *a = ap;
 3734 
 3735         if (!rc) {
 3736                 VFS_KNOTE_UNLOCKED(a->a_fdvp, NOTE_WRITE);
 3737                 VFS_KNOTE_UNLOCKED(a->a_tdvp, NOTE_WRITE);
 3738                 VFS_KNOTE_UNLOCKED(a->a_fvp, NOTE_RENAME);
 3739                 if (a->a_tvp)
 3740                         VFS_KNOTE_UNLOCKED(a->a_tvp, NOTE_DELETE);
 3741         }
 3742         if (a->a_tdvp != a->a_fdvp)
 3743                 vdrop(a->a_fdvp);
 3744         if (a->a_tvp != a->a_fvp)
 3745                 vdrop(a->a_fvp);
 3746         vdrop(a->a_tdvp);
 3747         if (a->a_tvp)
 3748                 vdrop(a->a_tvp);
 3749 }
 3750 
 3751 void
 3752 vop_rmdir_post(void *ap, int rc)
 3753 {
 3754         struct vop_rmdir_args *a = ap;
 3755 
 3756         if (!rc) {
 3757                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE | NOTE_LINK);
 3758                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_DELETE);
 3759         }
 3760 }
 3761 
 3762 void
 3763 vop_setattr_post(void *ap, int rc)
 3764 {
 3765         struct vop_setattr_args *a = ap;
 3766 
 3767         if (!rc)
 3768                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_ATTRIB);
 3769 }
 3770 
 3771 void
 3772 vop_symlink_post(void *ap, int rc)
 3773 {
 3774         struct vop_symlink_args *a = ap;
 3775 
 3776         if (!rc)
 3777                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 3778 }
 3779 
 3780 static struct knlist fs_knlist;
 3781 
 3782 static void
 3783 vfs_event_init(void *arg)
 3784 {
 3785         knlist_init(&fs_knlist, NULL, NULL, NULL, NULL);
 3786 }
 3787 /* XXX - correct order? */
 3788 SYSINIT(vfs_knlist, SI_SUB_VFS, SI_ORDER_ANY, vfs_event_init, NULL);
 3789 
 3790 void
 3791 vfs_event_signal(fsid_t *fsid, u_int32_t event, intptr_t data __unused)
 3792 {
 3793 
 3794         KNOTE_UNLOCKED(&fs_knlist, event);
 3795 }
 3796 
 3797 static int      filt_fsattach(struct knote *kn);
 3798 static void     filt_fsdetach(struct knote *kn);
 3799 static int      filt_fsevent(struct knote *kn, long hint);
 3800 
 3801 struct filterops fs_filtops =
 3802         { 0, filt_fsattach, filt_fsdetach, filt_fsevent };
 3803 
 3804 static int
 3805 filt_fsattach(struct knote *kn)
 3806 {
 3807 
 3808         kn->kn_flags |= EV_CLEAR;
 3809         knlist_add(&fs_knlist, kn, 0);
 3810         return (0);
 3811 }
 3812 
 3813 static void
 3814 filt_fsdetach(struct knote *kn)
 3815 {
 3816 
 3817         knlist_remove(&fs_knlist, kn, 0);
 3818 }
 3819 
 3820 static int
 3821 filt_fsevent(struct knote *kn, long hint)
 3822 {
 3823 
 3824         kn->kn_fflags |= hint;
 3825         return (kn->kn_fflags != 0);
 3826 }
 3827 
 3828 static int
 3829 sysctl_vfs_ctl(SYSCTL_HANDLER_ARGS)
 3830 {
 3831         struct vfsidctl vc;
 3832         int error;
 3833         struct mount *mp;
 3834 
 3835         error = SYSCTL_IN(req, &vc, sizeof(vc));
 3836         if (error)
 3837                 return (error);
 3838         if (vc.vc_vers != VFS_CTL_VERS1)
 3839                 return (EINVAL);
 3840         mp = vfs_getvfs(&vc.vc_fsid);
 3841         if (mp == NULL)
 3842                 return (ENOENT);
 3843         /* ensure that a specific sysctl goes to the right filesystem. */
 3844         if (strcmp(vc.vc_fstypename, "*") != 0 &&
 3845             strcmp(vc.vc_fstypename, mp->mnt_vfc->vfc_name) != 0) {
 3846                 vfs_rel(mp);
 3847                 return (EINVAL);
 3848         }
 3849         VCTLTOREQ(&vc, req);
 3850         error = VFS_SYSCTL(mp, vc.vc_op, req);
 3851         vfs_rel(mp);
 3852         return (error);
 3853 }
 3854 
 3855 SYSCTL_PROC(_vfs, OID_AUTO, ctl, CTLFLAG_WR, NULL, 0, sysctl_vfs_ctl, "",
 3856     "Sysctl by fsid");
 3857 
 3858 /*
 3859  * Function to initialize a va_filerev field sensibly.
 3860  * XXX: Wouldn't a random number make a lot more sense ??
 3861  */
 3862 u_quad_t
 3863 init_va_filerev(void)
 3864 {
 3865         struct bintime bt;
 3866 
 3867         getbinuptime(&bt);
 3868         return (((u_quad_t)bt.sec << 32LL) | (bt.frac >> 32LL));
 3869 }
 3870 
 3871 static int      filt_vfsread(struct knote *kn, long hint);
 3872 static int      filt_vfswrite(struct knote *kn, long hint);
 3873 static int      filt_vfsvnode(struct knote *kn, long hint);
 3874 static void     filt_vfsdetach(struct knote *kn);
 3875 static struct filterops vfsread_filtops =
 3876         { 1, NULL, filt_vfsdetach, filt_vfsread };
 3877 static struct filterops vfswrite_filtops =
 3878         { 1, NULL, filt_vfsdetach, filt_vfswrite };
 3879 static struct filterops vfsvnode_filtops =
 3880         { 1, NULL, filt_vfsdetach, filt_vfsvnode };
 3881 
 3882 static void
 3883 vfs_knllock(void *arg)
 3884 {
 3885         struct vnode *vp = arg;
 3886 
 3887         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, curthread);
 3888 }
 3889 
 3890 static void
 3891 vfs_knlunlock(void *arg)
 3892 {
 3893         struct vnode *vp = arg;
 3894 
 3895         VOP_UNLOCK(vp, 0, curthread);
 3896 }
 3897 
 3898 static int
 3899 vfs_knllocked(void *arg)
 3900 {
 3901         struct vnode *vp = arg;
 3902 
 3903         return (VOP_ISLOCKED(vp, curthread) == LK_EXCLUSIVE);
 3904 }
 3905 
 3906 int
 3907 vfs_kqfilter(struct vop_kqfilter_args *ap)
 3908 {
 3909         struct vnode *vp = ap->a_vp;
 3910         struct knote *kn = ap->a_kn;
 3911         struct knlist *knl;
 3912 
 3913         switch (kn->kn_filter) {
 3914         case EVFILT_READ:
 3915                 kn->kn_fop = &vfsread_filtops;
 3916                 break;
 3917         case EVFILT_WRITE:
 3918                 kn->kn_fop = &vfswrite_filtops;
 3919                 break;
 3920         case EVFILT_VNODE:
 3921                 kn->kn_fop = &vfsvnode_filtops;
 3922                 break;
 3923         default:
 3924                 return (EINVAL);
 3925         }
 3926 
 3927         kn->kn_hook = (caddr_t)vp;
 3928 
 3929         v_addpollinfo(vp);
 3930         if (vp->v_pollinfo == NULL)
 3931                 return (ENOMEM);
 3932         knl = &vp->v_pollinfo->vpi_selinfo.si_note;
 3933         knlist_add(knl, kn, 0);
 3934 
 3935         return (0);
 3936 }
 3937 
 3938 /*
 3939  * Detach knote from vnode
 3940  */
 3941 static void
 3942 filt_vfsdetach(struct knote *kn)
 3943 {
 3944         struct vnode *vp = (struct vnode *)kn->kn_hook;
 3945 
 3946         KASSERT(vp->v_pollinfo != NULL, ("Missing v_pollinfo"));
 3947         knlist_remove(&vp->v_pollinfo->vpi_selinfo.si_note, kn, 0);
 3948 }
 3949 
 3950 /*ARGSUSED*/
 3951 static int
 3952 filt_vfsread(struct knote *kn, long hint)
 3953 {
 3954         struct vnode *vp = (struct vnode *)kn->kn_hook;
 3955         struct vattr va;
 3956 
 3957         /*
 3958          * filesystem is gone, so set the EOF flag and schedule
 3959          * the knote for deletion.
 3960          */
 3961         if (hint == NOTE_REVOKE) {
 3962                 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 3963                 return (1);
 3964         }
 3965 
 3966         if (VOP_GETATTR(vp, &va, curthread->td_ucred, curthread))
 3967                 return (0);
 3968 
 3969         kn->kn_data = va.va_size - kn->kn_fp->f_offset;
 3970         return (kn->kn_data != 0);
 3971 }
 3972 
 3973 /*ARGSUSED*/
 3974 static int
 3975 filt_vfswrite(struct knote *kn, long hint)
 3976 {
 3977         /*
 3978          * filesystem is gone, so set the EOF flag and schedule
 3979          * the knote for deletion.
 3980          */
 3981         if (hint == NOTE_REVOKE)
 3982                 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 3983 
 3984         kn->kn_data = 0;
 3985         return (1);
 3986 }
 3987 
 3988 static int
 3989 filt_vfsvnode(struct knote *kn, long hint)
 3990 {
 3991         if (kn->kn_sfflags & hint)
 3992                 kn->kn_fflags |= hint;
 3993         if (hint == NOTE_REVOKE) {
 3994                 kn->kn_flags |= EV_EOF;
 3995                 return (1);
 3996         }
 3997         return (kn->kn_fflags != 0);
 3998 }
 3999 
 4000 int
 4001 vfs_read_dirent(struct vop_readdir_args *ap, struct dirent *dp, off_t off)
 4002 {
 4003         int error;
 4004 
 4005         if (dp->d_reclen > ap->a_uio->uio_resid)
 4006                 return (ENAMETOOLONG);
 4007         error = uiomove(dp, dp->d_reclen, ap->a_uio);
 4008         if (error) {
 4009                 if (ap->a_ncookies != NULL) {
 4010                         if (ap->a_cookies != NULL)
 4011                                 free(ap->a_cookies, M_TEMP);
 4012                         ap->a_cookies = NULL;
 4013                         *ap->a_ncookies = 0;
 4014                 }
 4015                 return (error);
 4016         }
 4017         if (ap->a_ncookies == NULL)
 4018                 return (0);
 4019 
 4020         KASSERT(ap->a_cookies,
 4021             ("NULL ap->a_cookies value with non-NULL ap->a_ncookies!"));
 4022 
 4023         *ap->a_cookies = realloc(*ap->a_cookies,
 4024             (*ap->a_ncookies + 1) * sizeof(u_long), M_TEMP, M_WAITOK | M_ZERO);
 4025         (*ap->a_cookies)[*ap->a_ncookies] = off;
 4026         return (0);
 4027 }
 4028 
 4029 /*
 4030  * Mark for update the access time of the file if the filesystem
 4031  * supports VA_MARK_ATIME.  This functionality is used by execve
 4032  * and mmap, so we want to avoid the synchronous I/O implied by
 4033  * directly setting va_atime for the sake of efficiency.
 4034  */
 4035 void
 4036 vfs_mark_atime(struct vnode *vp, struct thread *td)
 4037 {
 4038         struct vattr atimeattr;
 4039 
 4040         if ((vp->v_mount->mnt_flag & (MNT_NOATIME | MNT_RDONLY)) == 0) {
 4041                 VATTR_NULL(&atimeattr);
 4042                 atimeattr.va_vaflags |= VA_MARK_ATIME;
 4043                 (void)VOP_SETATTR(vp, &atimeattr, td->td_ucred, td);
 4044         }
 4045 }

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