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


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

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    1 /*-
    2  * Copyright (c) 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  * (c) UNIX System Laboratories, Inc.
    5  * All or some portions of this file are derived from material licensed
    6  * to the University of California by American Telephone and Telegraph
    7  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
    8  * the permission of UNIX System Laboratories, Inc.
    9  *
   10  * Redistribution and use in source and binary forms, with or without
   11  * modification, are permitted provided that the following conditions
   12  * are met:
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in the
   17  *    documentation and/or other materials provided with the distribution.
   18  * 4. Neither the name of the University nor the names of its contributors
   19  *    may be used to endorse or promote products derived from this software
   20  *    without specific prior written permission.
   21  *
   22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   32  * SUCH DAMAGE.
   33  *
   34  *      @(#)vfs_subr.c  8.31 (Berkeley) 5/26/95
   35  */
   36 
   37 /*
   38  * External virtual filesystem routines
   39  */
   40 
   41 #include <sys/cdefs.h>
   42 __FBSDID("$FreeBSD: releng/6.2/sys/kern/vfs_subr.c 164870 2006-12-04 08:47:53Z pjd $");
   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/kdb.h>
   59 #include <sys/kernel.h>
   60 #include <sys/kthread.h>
   61 #include <sys/mac.h>
   62 #include <sys/malloc.h>
   63 #include <sys/mount.h>
   64 #include <sys/namei.h>
   65 #include <sys/reboot.h>
   66 #include <sys/sleepqueue.h>
   67 #include <sys/stat.h>
   68 #include <sys/sysctl.h>
   69 #include <sys/syslog.h>
   70 #include <sys/vmmeter.h>
   71 #include <sys/vnode.h>
   72 
   73 #include <machine/stdarg.h>
   74 
   75 #include <vm/vm.h>
   76 #include <vm/vm_object.h>
   77 #include <vm/vm_extern.h>
   78 #include <vm/pmap.h>
   79 #include <vm/vm_map.h>
   80 #include <vm/vm_page.h>
   81 #include <vm/vm_kern.h>
   82 #include <vm/uma.h>
   83 
   84 #ifdef DDB
   85 #include <ddb/ddb.h>
   86 #endif
   87 
   88 static MALLOC_DEFINE(M_NETADDR, "Export Host", "Export host address structure");
   89 
   90 static void     delmntque(struct vnode *vp);
   91 static void     insmntque(struct vnode *vp, struct mount *mp);
   92 static int      flushbuflist(struct bufv *bufv, int flags, struct bufobj *bo,
   93                     int slpflag, int slptimeo);
   94 static void     syncer_shutdown(void *arg, int howto);
   95 static int      vtryrecycle(struct vnode *vp);
   96 static void     vbusy(struct vnode *vp);
   97 static void     vdropl(struct vnode *vp);
   98 static void     vinactive(struct vnode *, struct thread *);
   99 static void     v_incr_usecount(struct vnode *);
  100 static void     v_decr_usecount(struct vnode *);
  101 static void     v_decr_useonly(struct vnode *);
  102 static void     v_upgrade_usecount(struct vnode *);
  103 static void     vfree(struct vnode *);
  104 static void     vnlru_free(int);
  105 static void     vdestroy(struct vnode *);
  106 static void     vgonel(struct vnode *);
  107 static void     vfs_knllock(void *arg);
  108 static void     vfs_knlunlock(void *arg);
  109 static int      vfs_knllocked(void *arg);
  110 
  111 
  112 /*
  113  * Enable Giant pushdown based on whether or not the vm is mpsafe in this
  114  * build.  Without mpsafevm the buffer cache can not run Giant free.
  115  */
  116 #if defined(__alpha__) || defined(__amd64__) || defined(__i386__) || \
  117         defined(__sparc64__)
  118 int mpsafe_vfs = 1;
  119 #else
  120 int mpsafe_vfs;
  121 #endif
  122 TUNABLE_INT("debug.mpsafevfs", &mpsafe_vfs);
  123 SYSCTL_INT(_debug, OID_AUTO, mpsafevfs, CTLFLAG_RD, &mpsafe_vfs, 0,
  124     "MPSAFE VFS");
  125 
  126 /*
  127  * Number of vnodes in existence.  Increased whenever getnewvnode()
  128  * allocates a new vnode, decreased on vdestroy() called on VI_DOOMed
  129  * vnode.
  130  */
  131 static unsigned long    numvnodes;
  132 
  133 SYSCTL_LONG(_vfs, OID_AUTO, numvnodes, CTLFLAG_RD, &numvnodes, 0, "");
  134 
  135 /*
  136  * Conversion tables for conversion from vnode types to inode formats
  137  * and back.
  138  */
  139 enum vtype iftovt_tab[16] = {
  140         VNON, VFIFO, VCHR, VNON, VDIR, VNON, VBLK, VNON,
  141         VREG, VNON, VLNK, VNON, VSOCK, VNON, VNON, VBAD,
  142 };
  143 int vttoif_tab[10] = {
  144         0, S_IFREG, S_IFDIR, S_IFBLK, S_IFCHR, S_IFLNK,
  145         S_IFSOCK, S_IFIFO, S_IFMT, S_IFMT
  146 };
  147 
  148 /*
  149  * List of vnodes that are ready for recycling.
  150  */
  151 static TAILQ_HEAD(freelst, vnode) vnode_free_list;
  152 
  153 /*
  154  * Free vnode target.  Free vnodes may simply be files which have been stat'd
  155  * but not read.  This is somewhat common, and a small cache of such files
  156  * should be kept to avoid recreation costs.
  157  */
  158 static u_long wantfreevnodes;
  159 SYSCTL_LONG(_vfs, OID_AUTO, wantfreevnodes, CTLFLAG_RW, &wantfreevnodes, 0, "");
  160 /* Number of vnodes in the free list. */
  161 static u_long freevnodes;
  162 SYSCTL_LONG(_vfs, OID_AUTO, freevnodes, CTLFLAG_RD, &freevnodes, 0, "");
  163 
  164 /*
  165  * Various variables used for debugging the new implementation of
  166  * reassignbuf().
  167  * XXX these are probably of (very) limited utility now.
  168  */
  169 static int reassignbufcalls;
  170 SYSCTL_INT(_vfs, OID_AUTO, reassignbufcalls, CTLFLAG_RW, &reassignbufcalls, 0, "");
  171 
  172 /*
  173  * Cache for the mount type id assigned to NFS.  This is used for
  174  * special checks in nfs/nfs_nqlease.c and vm/vnode_pager.c.
  175  */
  176 int     nfs_mount_type = -1;
  177 
  178 /* To keep more than one thread at a time from running vfs_getnewfsid */
  179 static struct mtx mntid_mtx;
  180 
  181 /*
  182  * Lock for any access to the following:
  183  *      vnode_free_list
  184  *      numvnodes
  185  *      freevnodes
  186  */
  187 static struct mtx vnode_free_list_mtx;
  188 
  189 /* Publicly exported FS */
  190 struct nfs_public nfs_pub;
  191 
  192 /* Zone for allocation of new vnodes - used exclusively by getnewvnode() */
  193 static uma_zone_t vnode_zone;
  194 static uma_zone_t vnodepoll_zone;
  195 
  196 /* Set to 1 to print out reclaim of active vnodes */
  197 int     prtactive;
  198 
  199 /*
  200  * The workitem queue.
  201  *
  202  * It is useful to delay writes of file data and filesystem metadata
  203  * for tens of seconds so that quickly created and deleted files need
  204  * not waste disk bandwidth being created and removed. To realize this,
  205  * we append vnodes to a "workitem" queue. When running with a soft
  206  * updates implementation, most pending metadata dependencies should
  207  * not wait for more than a few seconds. Thus, mounted on block devices
  208  * are delayed only about a half the time that file data is delayed.
  209  * Similarly, directory updates are more critical, so are only delayed
  210  * about a third the time that file data is delayed. Thus, there are
  211  * SYNCER_MAXDELAY queues that are processed round-robin at a rate of
  212  * one each second (driven off the filesystem syncer process). The
  213  * syncer_delayno variable indicates the next queue that is to be processed.
  214  * Items that need to be processed soon are placed in this queue:
  215  *
  216  *      syncer_workitem_pending[syncer_delayno]
  217  *
  218  * A delay of fifteen seconds is done by placing the request fifteen
  219  * entries later in the queue:
  220  *
  221  *      syncer_workitem_pending[(syncer_delayno + 15) & syncer_mask]
  222  *
  223  */
  224 static int syncer_delayno;
  225 static long syncer_mask;
  226 LIST_HEAD(synclist, bufobj);
  227 static struct synclist *syncer_workitem_pending;
  228 /*
  229  * The sync_mtx protects:
  230  *      bo->bo_synclist
  231  *      sync_vnode_count
  232  *      syncer_delayno
  233  *      syncer_state
  234  *      syncer_workitem_pending
  235  *      syncer_worklist_len
  236  *      rushjob
  237  */
  238 static struct mtx sync_mtx;
  239 
  240 #define SYNCER_MAXDELAY         32
  241 static int syncer_maxdelay = SYNCER_MAXDELAY;   /* maximum delay time */
  242 static int syncdelay = 30;              /* max time to delay syncing data */
  243 static int filedelay = 30;              /* time to delay syncing files */
  244 SYSCTL_INT(_kern, OID_AUTO, filedelay, CTLFLAG_RW, &filedelay, 0, "");
  245 static int dirdelay = 29;               /* time to delay syncing directories */
  246 SYSCTL_INT(_kern, OID_AUTO, dirdelay, CTLFLAG_RW, &dirdelay, 0, "");
  247 static int metadelay = 28;              /* time to delay syncing metadata */
  248 SYSCTL_INT(_kern, OID_AUTO, metadelay, CTLFLAG_RW, &metadelay, 0, "");
  249 static int rushjob;             /* number of slots to run ASAP */
  250 static int stat_rush_requests;  /* number of times I/O speeded up */
  251 SYSCTL_INT(_debug, OID_AUTO, rush_requests, CTLFLAG_RW, &stat_rush_requests, 0, "");
  252 
  253 /*
  254  * When shutting down the syncer, run it at four times normal speed.
  255  */
  256 #define SYNCER_SHUTDOWN_SPEEDUP         4
  257 static int sync_vnode_count;
  258 static int syncer_worklist_len;
  259 static enum { SYNCER_RUNNING, SYNCER_SHUTTING_DOWN, SYNCER_FINAL_DELAY }
  260     syncer_state;
  261 
  262 /*
  263  * Number of vnodes we want to exist at any one time.  This is mostly used
  264  * to size hash tables in vnode-related code.  It is normally not used in
  265  * getnewvnode(), as wantfreevnodes is normally nonzero.)
  266  *
  267  * XXX desiredvnodes is historical cruft and should not exist.
  268  */
  269 int desiredvnodes;
  270 SYSCTL_INT(_kern, KERN_MAXVNODES, maxvnodes, CTLFLAG_RW,
  271     &desiredvnodes, 0, "Maximum number of vnodes");
  272 SYSCTL_INT(_kern, OID_AUTO, minvnodes, CTLFLAG_RW,
  273     &wantfreevnodes, 0, "Minimum number of vnodes (legacy)");
  274 static int vnlru_nowhere;
  275 SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RW,
  276     &vnlru_nowhere, 0, "Number of times the vnlru process ran without success");
  277 
  278 /*
  279  * Macros to control when a vnode is freed and recycled.  All require
  280  * the vnode interlock.
  281  */
  282 #define VCANRECYCLE(vp) (((vp)->v_iflag & VI_FREE) && !(vp)->v_holdcnt)
  283 #define VSHOULDFREE(vp) (!((vp)->v_iflag & VI_FREE) && !(vp)->v_holdcnt)
  284 #define VSHOULDBUSY(vp) (((vp)->v_iflag & VI_FREE) && (vp)->v_holdcnt)
  285 
  286 
  287 /*
  288  * Initialize the vnode management data structures.
  289  */
  290 #ifndef MAXVNODES_MAX
  291 #define MAXVNODES_MAX   100000
  292 #endif
  293 static void
  294 vntblinit(void *dummy __unused)
  295 {
  296 
  297         /*
  298          * Desiredvnodes is a function of the physical memory size and
  299          * the kernel's heap size.  Specifically, desiredvnodes scales
  300          * in proportion to the physical memory size until two fifths
  301          * of the kernel's heap size is consumed by vnodes and vm
  302          * objects.
  303          */
  304         desiredvnodes = min(maxproc + cnt.v_page_count / 4, 2 * vm_kmem_size /
  305             (5 * (sizeof(struct vm_object) + sizeof(struct vnode))));
  306         if (desiredvnodes > MAXVNODES_MAX) {
  307                 if (bootverbose)
  308                         printf("Reducing kern.maxvnodes %d -> %d\n",
  309                             desiredvnodes, MAXVNODES_MAX);
  310                 desiredvnodes = MAXVNODES_MAX;
  311         }
  312         wantfreevnodes = desiredvnodes / 4; 
  313         mtx_init(&mntid_mtx, "mntid", NULL, MTX_DEF);
  314         TAILQ_INIT(&vnode_free_list);
  315         mtx_init(&vnode_free_list_mtx, "vnode_free_list", NULL, MTX_DEF);
  316         vnode_zone = uma_zcreate("VNODE", sizeof (struct vnode), NULL, NULL,
  317             NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  318         vnodepoll_zone = uma_zcreate("VNODEPOLL", sizeof (struct vpollinfo),
  319               NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
  320         /*
  321          * Initialize the filesystem syncer.
  322          */
  323         syncer_workitem_pending = hashinit(syncer_maxdelay, M_VNODE,
  324                 &syncer_mask);
  325         syncer_maxdelay = syncer_mask + 1;
  326         mtx_init(&sync_mtx, "Syncer mtx", NULL, MTX_DEF);
  327 }
  328 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_FIRST, vntblinit, NULL)
  329 
  330 
  331 /*
  332  * Mark a mount point as busy. Used to synchronize access and to delay
  333  * unmounting. Interlock is not released on failure.
  334  */
  335 int
  336 vfs_busy(mp, flags, interlkp, td)
  337         struct mount *mp;
  338         int flags;
  339         struct mtx *interlkp;
  340         struct thread *td;
  341 {
  342         int lkflags;
  343 
  344         MNT_ILOCK(mp);
  345         MNT_REF(mp);
  346         if (mp->mnt_kern_flag & MNTK_UNMOUNT) {
  347                 if (flags & LK_NOWAIT) {
  348                         MNT_REL(mp);
  349                         MNT_IUNLOCK(mp);
  350                         return (ENOENT);
  351                 }
  352                 if (interlkp)
  353                         mtx_unlock(interlkp);
  354                 mp->mnt_kern_flag |= MNTK_MWAIT;
  355                 /*
  356                  * Since all busy locks are shared except the exclusive
  357                  * lock granted when unmounting, the only place that a
  358                  * wakeup needs to be done is at the release of the
  359                  * exclusive lock at the end of dounmount.
  360                  */
  361                 msleep(mp, MNT_MTX(mp), PVFS, "vfs_busy", 0);
  362                 MNT_REL(mp);
  363                 MNT_IUNLOCK(mp);
  364                 if (interlkp)
  365                         mtx_lock(interlkp);
  366                 return (ENOENT);
  367         }
  368         if (interlkp)
  369                 mtx_unlock(interlkp);
  370         lkflags = LK_SHARED | LK_INTERLOCK;
  371         if (lockmgr(&mp->mnt_lock, lkflags, MNT_MTX(mp), td))
  372                 panic("vfs_busy: unexpected lock failure");
  373         return (0);
  374 }
  375 
  376 /*
  377  * Free a busy filesystem.
  378  */
  379 void
  380 vfs_unbusy(mp, td)
  381         struct mount *mp;
  382         struct thread *td;
  383 {
  384 
  385         lockmgr(&mp->mnt_lock, LK_RELEASE, NULL, td);
  386         vfs_rel(mp);
  387 }
  388 
  389 /*
  390  * Lookup a mount point by filesystem identifier.
  391  */
  392 struct mount *
  393 vfs_getvfs(fsid)
  394         fsid_t *fsid;
  395 {
  396         struct mount *mp;
  397 
  398         mtx_lock(&mountlist_mtx);
  399         TAILQ_FOREACH(mp, &mountlist, mnt_list) {
  400                 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
  401                     mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
  402                         vfs_ref(mp);
  403                         mtx_unlock(&mountlist_mtx);
  404                         return (mp);
  405                 }
  406         }
  407         mtx_unlock(&mountlist_mtx);
  408         return ((struct mount *) 0);
  409 }
  410 
  411 /*
  412  * Check if a user can access priveledged mount options.
  413  */
  414 int
  415 vfs_suser(struct mount *mp, struct thread *td)
  416 {
  417         int error;
  418 
  419         if ((mp->mnt_flag & MNT_USER) == 0 ||
  420             mp->mnt_cred->cr_uid != td->td_ucred->cr_uid) {
  421                 if ((error = suser(td)) != 0)
  422                         return (error);
  423         }
  424         return (0);
  425 }
  426 
  427 /*
  428  * Get a new unique fsid.  Try to make its val[0] unique, since this value
  429  * will be used to create fake device numbers for stat().  Also try (but
  430  * not so hard) make its val[0] unique mod 2^16, since some emulators only
  431  * support 16-bit device numbers.  We end up with unique val[0]'s for the
  432  * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls.
  433  *
  434  * Keep in mind that several mounts may be running in parallel.  Starting
  435  * the search one past where the previous search terminated is both a
  436  * micro-optimization and a defense against returning the same fsid to
  437  * different mounts.
  438  */
  439 void
  440 vfs_getnewfsid(mp)
  441         struct mount *mp;
  442 {
  443         static u_int16_t mntid_base;
  444         struct mount *nmp;
  445         fsid_t tfsid;
  446         int mtype;
  447 
  448         mtx_lock(&mntid_mtx);
  449         mtype = mp->mnt_vfc->vfc_typenum;
  450         tfsid.val[1] = mtype;
  451         mtype = (mtype & 0xFF) << 24;
  452         for (;;) {
  453                 tfsid.val[0] = makedev(255,
  454                     mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF));
  455                 mntid_base++;
  456                 if ((nmp = vfs_getvfs(&tfsid)) == NULL)
  457                         break;
  458                 vfs_rel(nmp);
  459         }
  460         mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
  461         mp->mnt_stat.f_fsid.val[1] = tfsid.val[1];
  462         mtx_unlock(&mntid_mtx);
  463 }
  464 
  465 /*
  466  * Knob to control the precision of file timestamps:
  467  *
  468  *   0 = seconds only; nanoseconds zeroed.
  469  *   1 = seconds and nanoseconds, accurate within 1/HZ.
  470  *   2 = seconds and nanoseconds, truncated to microseconds.
  471  * >=3 = seconds and nanoseconds, maximum precision.
  472  */
  473 enum { TSP_SEC, TSP_HZ, TSP_USEC, TSP_NSEC };
  474 
  475 static int timestamp_precision = TSP_SEC;
  476 SYSCTL_INT(_vfs, OID_AUTO, timestamp_precision, CTLFLAG_RW,
  477     &timestamp_precision, 0, "");
  478 
  479 /*
  480  * Get a current timestamp.
  481  */
  482 void
  483 vfs_timestamp(tsp)
  484         struct timespec *tsp;
  485 {
  486         struct timeval tv;
  487 
  488         switch (timestamp_precision) {
  489         case TSP_SEC:
  490                 tsp->tv_sec = time_second;
  491                 tsp->tv_nsec = 0;
  492                 break;
  493         case TSP_HZ:
  494                 getnanotime(tsp);
  495                 break;
  496         case TSP_USEC:
  497                 microtime(&tv);
  498                 TIMEVAL_TO_TIMESPEC(&tv, tsp);
  499                 break;
  500         case TSP_NSEC:
  501         default:
  502                 nanotime(tsp);
  503                 break;
  504         }
  505 }
  506 
  507 /*
  508  * Set vnode attributes to VNOVAL
  509  */
  510 void
  511 vattr_null(vap)
  512         struct vattr *vap;
  513 {
  514 
  515         vap->va_type = VNON;
  516         vap->va_size = VNOVAL;
  517         vap->va_bytes = VNOVAL;
  518         vap->va_mode = VNOVAL;
  519         vap->va_nlink = VNOVAL;
  520         vap->va_uid = VNOVAL;
  521         vap->va_gid = VNOVAL;
  522         vap->va_fsid = VNOVAL;
  523         vap->va_fileid = VNOVAL;
  524         vap->va_blocksize = VNOVAL;
  525         vap->va_rdev = VNOVAL;
  526         vap->va_atime.tv_sec = VNOVAL;
  527         vap->va_atime.tv_nsec = VNOVAL;
  528         vap->va_mtime.tv_sec = VNOVAL;
  529         vap->va_mtime.tv_nsec = VNOVAL;
  530         vap->va_ctime.tv_sec = VNOVAL;
  531         vap->va_ctime.tv_nsec = VNOVAL;
  532         vap->va_birthtime.tv_sec = VNOVAL;
  533         vap->va_birthtime.tv_nsec = VNOVAL;
  534         vap->va_flags = VNOVAL;
  535         vap->va_gen = VNOVAL;
  536         vap->va_vaflags = 0;
  537 }
  538 
  539 /*
  540  * This routine is called when we have too many vnodes.  It attempts
  541  * to free <count> vnodes and will potentially free vnodes that still
  542  * have VM backing store (VM backing store is typically the cause
  543  * of a vnode blowout so we want to do this).  Therefore, this operation
  544  * is not considered cheap.
  545  *
  546  * A number of conditions may prevent a vnode from being reclaimed.
  547  * the buffer cache may have references on the vnode, a directory
  548  * vnode may still have references due to the namei cache representing
  549  * underlying files, or the vnode may be in active use.   It is not
  550  * desireable to reuse such vnodes.  These conditions may cause the
  551  * number of vnodes to reach some minimum value regardless of what
  552  * you set kern.maxvnodes to.  Do not set kern.maxvnodes too low.
  553  */
  554 static int
  555 vlrureclaim(struct mount *mp)
  556 {
  557         struct thread *td;
  558         struct vnode *vp;
  559         int done;
  560         int trigger;
  561         int usevnodes;
  562         int count;
  563 
  564         /*
  565          * Calculate the trigger point, don't allow user
  566          * screwups to blow us up.   This prevents us from
  567          * recycling vnodes with lots of resident pages.  We
  568          * aren't trying to free memory, we are trying to
  569          * free vnodes.
  570          */
  571         usevnodes = desiredvnodes;
  572         if (usevnodes <= 0)
  573                 usevnodes = 1;
  574         trigger = cnt.v_page_count * 2 / usevnodes;
  575         done = 0;
  576         td = curthread;
  577         vn_start_write(NULL, &mp, V_WAIT);
  578         MNT_ILOCK(mp);
  579         count = mp->mnt_nvnodelistsize / 10 + 1;
  580         while (count != 0) {
  581                 vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
  582                 while (vp != NULL && vp->v_type == VMARKER)
  583                         vp = TAILQ_NEXT(vp, v_nmntvnodes);
  584                 if (vp == NULL)
  585                         break;
  586                 TAILQ_REMOVE(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
  587                 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
  588                 --count;
  589                 if (!VI_TRYLOCK(vp))
  590                         goto next_iter;
  591                 /*
  592                  * If it's been deconstructed already, it's still
  593                  * referenced, or it exceeds the trigger, skip it.
  594                  */
  595                 if (vp->v_usecount || !LIST_EMPTY(&(vp)->v_cache_src) ||
  596                     (vp->v_iflag & VI_DOOMED) != 0 || (vp->v_object != NULL &&
  597                     vp->v_object->resident_page_count > trigger)) {
  598                         VI_UNLOCK(vp);
  599                         goto next_iter;
  600                 }
  601                 MNT_IUNLOCK(mp);
  602                 vholdl(vp);
  603                 if (VOP_LOCK(vp, LK_INTERLOCK|LK_EXCLUSIVE|LK_NOWAIT, td)) {
  604                         vdrop(vp);
  605                         goto next_iter_mntunlocked;
  606                 }
  607                 VI_LOCK(vp);
  608                 /*
  609                  * v_usecount may have been bumped after VOP_LOCK() dropped
  610                  * the vnode interlock and before it was locked again.
  611                  *
  612                  * It is not necessary to recheck VI_DOOMED because it can
  613                  * only be set by another thread that holds both the vnode
  614                  * lock and vnode interlock.  If another thread has the
  615                  * vnode lock before we get to VOP_LOCK() and obtains the
  616                  * vnode interlock after VOP_LOCK() drops the vnode
  617                  * interlock, the other thread will be unable to drop the
  618                  * vnode lock before our VOP_LOCK() call fails.
  619                  */
  620                 if (vp->v_usecount || !LIST_EMPTY(&(vp)->v_cache_src) ||
  621                     (vp->v_object != NULL && 
  622                     vp->v_object->resident_page_count > trigger)) {
  623                         VOP_UNLOCK(vp, LK_INTERLOCK, td);
  624                         goto next_iter_mntunlocked;
  625                 }
  626                 KASSERT((vp->v_iflag & VI_DOOMED) == 0,
  627                     ("VI_DOOMED unexpectedly detected in vlrureclaim()"));
  628                 vgonel(vp);
  629                 VOP_UNLOCK(vp, 0, td);
  630                 vdropl(vp);
  631                 done++;
  632 next_iter_mntunlocked:
  633                 if ((count % 256) != 0)
  634                         goto relock_mnt;
  635                 goto yield;
  636 next_iter:
  637                 if ((count % 256) != 0)
  638                         continue;
  639                 MNT_IUNLOCK(mp);
  640 yield:
  641                 uio_yield();
  642 relock_mnt:
  643                 MNT_ILOCK(mp);
  644         }
  645         MNT_IUNLOCK(mp);
  646         vn_finished_write(mp);
  647         return done;
  648 }
  649 
  650 /*
  651  * Attempt to keep the free list at wantfreevnodes length.
  652  */
  653 static void
  654 vnlru_free(int count)
  655 {
  656         struct vnode *vp;
  657         int vfslocked;
  658 
  659         mtx_assert(&vnode_free_list_mtx, MA_OWNED);
  660         for (; count > 0; count--) {
  661                 vp = TAILQ_FIRST(&vnode_free_list);
  662                 /*
  663                  * The list can be modified while the free_list_mtx
  664                  * has been dropped and vp could be NULL here.
  665                  */
  666                 if (!vp)
  667                         break;
  668                 VNASSERT(vp->v_op != NULL, vp,
  669                     ("vnlru_free: vnode already reclaimed."));
  670                 TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
  671                 /*
  672                  * Don't recycle if we can't get the interlock.
  673                  */
  674                 if (!VI_TRYLOCK(vp)) {
  675                         TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
  676                         continue;
  677                 }
  678                 VNASSERT(VCANRECYCLE(vp), vp,
  679                     ("vp inconsistent on freelist"));
  680                 freevnodes--;
  681                 vp->v_iflag &= ~VI_FREE;
  682                 vholdl(vp);
  683                 mtx_unlock(&vnode_free_list_mtx);
  684                 VI_UNLOCK(vp);
  685                 vfslocked = VFS_LOCK_GIANT(vp->v_mount);
  686                 vtryrecycle(vp);
  687                 VFS_UNLOCK_GIANT(vfslocked);
  688                 /*
  689                  * If the recycled succeeded this vdrop will actually free
  690                  * the vnode.  If not it will simply place it back on
  691                  * the free list.
  692                  */
  693                 vdrop(vp);
  694                 mtx_lock(&vnode_free_list_mtx);
  695         }
  696 }
  697 /*
  698  * Attempt to recycle vnodes in a context that is always safe to block.
  699  * Calling vlrurecycle() from the bowels of filesystem code has some
  700  * interesting deadlock problems.
  701  */
  702 static struct proc *vnlruproc;
  703 static int vnlruproc_sig;
  704 
  705 static void
  706 vnlru_proc(void)
  707 {
  708         struct mount *mp, *nmp;
  709         int done;
  710         struct proc *p = vnlruproc;
  711         struct thread *td = FIRST_THREAD_IN_PROC(p);
  712 
  713         mtx_lock(&Giant);
  714 
  715         EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, p,
  716             SHUTDOWN_PRI_FIRST);
  717 
  718         for (;;) {
  719                 kthread_suspend_check(p);
  720                 mtx_lock(&vnode_free_list_mtx);
  721                 if (freevnodes > wantfreevnodes)
  722                         vnlru_free(freevnodes - wantfreevnodes);
  723                 if (numvnodes <= desiredvnodes * 9 / 10) {
  724                         vnlruproc_sig = 0;
  725                         wakeup(&vnlruproc_sig);
  726                         msleep(vnlruproc, &vnode_free_list_mtx,
  727                             PVFS|PDROP, "vlruwt", hz);
  728                         continue;
  729                 }
  730                 mtx_unlock(&vnode_free_list_mtx);
  731                 done = 0;
  732                 mtx_lock(&mountlist_mtx);
  733                 for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
  734                         int vfsunlocked;
  735                         if (vfs_busy(mp, LK_NOWAIT, &mountlist_mtx, td)) {
  736                                 nmp = TAILQ_NEXT(mp, mnt_list);
  737                                 continue;
  738                         }
  739                         if (!VFS_NEEDSGIANT(mp)) {
  740                                 mtx_unlock(&Giant);
  741                                 vfsunlocked = 1;
  742                         } else
  743                                 vfsunlocked = 0;
  744                         done += vlrureclaim(mp);
  745                         if (vfsunlocked)
  746                                 mtx_lock(&Giant);
  747                         mtx_lock(&mountlist_mtx);
  748                         nmp = TAILQ_NEXT(mp, mnt_list);
  749                         vfs_unbusy(mp, td);
  750                 }
  751                 mtx_unlock(&mountlist_mtx);
  752                 if (done == 0) {
  753 #if 0
  754                         /* These messages are temporary debugging aids */
  755                         if (vnlru_nowhere < 5)
  756                                 printf("vnlru process getting nowhere..\n");
  757                         else if (vnlru_nowhere == 5)
  758                                 printf("vnlru process messages stopped.\n");
  759 #endif
  760                         vnlru_nowhere++;
  761                         tsleep(vnlruproc, PPAUSE, "vlrup", hz * 3);
  762                 } else 
  763                         uio_yield();
  764         }
  765 }
  766 
  767 static struct kproc_desc vnlru_kp = {
  768         "vnlru",
  769         vnlru_proc,
  770         &vnlruproc
  771 };
  772 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp)
  773 
  774 /*
  775  * Routines having to do with the management of the vnode table.
  776  */
  777 
  778 static void
  779 vdestroy(struct vnode *vp)
  780 {
  781         struct bufobj *bo;
  782 
  783         CTR1(KTR_VFS, "vdestroy vp %p", vp);
  784         mtx_lock(&vnode_free_list_mtx);
  785         numvnodes--;
  786         mtx_unlock(&vnode_free_list_mtx);
  787         bo = &vp->v_bufobj;
  788         VNASSERT((vp->v_iflag & VI_FREE) == 0, vp,
  789             ("cleaned vnode still on the free list."));
  790         VNASSERT(vp->v_data == NULL, vp, ("cleaned vnode isn't"));
  791         VNASSERT(vp->v_holdcnt == 0, vp, ("Non-zero hold count"));
  792         VNASSERT(vp->v_usecount == 0, vp, ("Non-zero use count"));
  793         VNASSERT(vp->v_writecount == 0, vp, ("Non-zero write count"));
  794         VNASSERT(bo->bo_numoutput == 0, vp, ("Clean vnode has pending I/O's"));
  795         VNASSERT(bo->bo_clean.bv_cnt == 0, vp, ("cleanbufcnt not 0"));
  796         VNASSERT(bo->bo_clean.bv_root == NULL, vp, ("cleanblkroot not NULL"));
  797         VNASSERT(bo->bo_dirty.bv_cnt == 0, vp, ("dirtybufcnt not 0"));
  798         VNASSERT(bo->bo_dirty.bv_root == NULL, vp, ("dirtyblkroot not NULL"));
  799         VNASSERT(TAILQ_EMPTY(&vp->v_cache_dst), vp, ("vp has namecache dst"));
  800         VNASSERT(LIST_EMPTY(&vp->v_cache_src), vp, ("vp has namecache src"));
  801         VI_UNLOCK(vp);
  802 #ifdef MAC
  803         mac_destroy_vnode(vp);
  804 #endif
  805         if (vp->v_pollinfo != NULL) {
  806                 knlist_destroy(&vp->v_pollinfo->vpi_selinfo.si_note);
  807                 mtx_destroy(&vp->v_pollinfo->vpi_lock);
  808                 uma_zfree(vnodepoll_zone, vp->v_pollinfo);
  809         }
  810 #ifdef INVARIANTS
  811         /* XXX Elsewhere we can detect an already freed vnode via NULL v_op. */
  812         vp->v_op = NULL;
  813 #endif
  814         lockdestroy(vp->v_vnlock);
  815         mtx_destroy(&vp->v_interlock);
  816         uma_zfree(vnode_zone, vp);
  817 }
  818 
  819 /*
  820  * Try to recycle a freed vnode.  We abort if anyone picks up a reference
  821  * before we actually vgone().  This function must be called with the vnode
  822  * held to prevent the vnode from being returned to the free list midway
  823  * through vgone().
  824  */
  825 static int
  826 vtryrecycle(struct vnode *vp)
  827 {
  828         struct thread *td = curthread;
  829         struct mount *vnmp;
  830 
  831         CTR1(KTR_VFS, "vtryrecycle: trying vp %p", vp);
  832         VNASSERT(vp->v_holdcnt, vp,
  833             ("vtryrecycle: Recycling vp %p without a reference.", vp));
  834         /*
  835          * This vnode may found and locked via some other list, if so we
  836          * can't recycle it yet.
  837          */
  838         if (VOP_LOCK(vp, LK_EXCLUSIVE | LK_NOWAIT, td) != 0)
  839                 return (EWOULDBLOCK);
  840         /*
  841          * Don't recycle if its filesystem is being suspended.
  842          */
  843         if (vn_start_write(vp, &vnmp, V_NOWAIT) != 0) {
  844                 VOP_UNLOCK(vp, 0, td);
  845                 return (EBUSY);
  846         }
  847         /*
  848          * If we got this far, we need to acquire the interlock and see if
  849          * anyone picked up this vnode from another list.  If not, we will
  850          * mark it with DOOMED via vgonel() so that anyone who does find it
  851          * will skip over it.
  852          */
  853         VI_LOCK(vp);
  854         if (vp->v_usecount) {
  855                 VOP_UNLOCK(vp, LK_INTERLOCK, td);
  856                 vn_finished_write(vnmp);
  857                 return (EBUSY);
  858         }
  859         if ((vp->v_iflag & VI_DOOMED) == 0)
  860                 vgonel(vp);
  861         VOP_UNLOCK(vp, LK_INTERLOCK, td);
  862         vn_finished_write(vnmp);
  863         CTR1(KTR_VFS, "vtryrecycle: recycled vp %p", vp);
  864         return (0);
  865 }
  866 
  867 /*
  868  * Return the next vnode from the free list.
  869  */
  870 int
  871 getnewvnode(tag, mp, vops, vpp)
  872         const char *tag;
  873         struct mount *mp;
  874         struct vop_vector *vops;
  875         struct vnode **vpp;
  876 {
  877         struct vnode *vp = NULL;
  878         struct bufobj *bo;
  879 
  880         mtx_lock(&vnode_free_list_mtx);
  881         /*
  882          * Lend our context to reclaim vnodes if they've exceeded the max.
  883          */
  884         if (freevnodes > wantfreevnodes)
  885                 vnlru_free(1);
  886         /*
  887          * Wait for available vnodes.
  888          */
  889         if (numvnodes > desiredvnodes) {
  890                 if (mp != NULL && (mp->mnt_kern_flag & MNTK_SUSPEND)) {
  891                         /*
  892                          * File system is beeing suspended, we cannot risk a
  893                          * deadlock here, so allocate new vnode anyway.
  894                          */
  895                         if (freevnodes > wantfreevnodes)
  896                                 vnlru_free(freevnodes - wantfreevnodes);
  897                         goto alloc;
  898                 }
  899                 if (vnlruproc_sig == 0) {
  900                         vnlruproc_sig = 1;      /* avoid unnecessary wakeups */
  901                         wakeup(vnlruproc);
  902                 }
  903                 msleep(&vnlruproc_sig, &vnode_free_list_mtx, PVFS,
  904                     "vlruwk", hz);
  905 #if 0   /* XXX Not all VFS_VGET/ffs_vget callers check returns. */
  906                 if (numvnodes > desiredvnodes) {
  907                         mtx_unlock(&vnode_free_list_mtx);
  908                         return (ENFILE);
  909                 }
  910 #endif
  911         }
  912 alloc:
  913         numvnodes++;
  914         mtx_unlock(&vnode_free_list_mtx);
  915         vp = (struct vnode *) uma_zalloc(vnode_zone, M_WAITOK|M_ZERO);
  916         /*
  917          * Setup locks.
  918          */
  919         vp->v_vnlock = &vp->v_lock;
  920         mtx_init(&vp->v_interlock, "vnode interlock", NULL, MTX_DEF);
  921         /*
  922          * By default, don't allow shared locks unless filesystems
  923          * opt-in.
  924          */
  925         lockinit(vp->v_vnlock, PVFS, tag, VLKTIMEOUT, LK_NOSHARE);
  926         /*
  927          * Initialize bufobj.
  928          */
  929         bo = &vp->v_bufobj;
  930         bo->__bo_vnode = vp;
  931         bo->bo_mtx = &vp->v_interlock;
  932         bo->bo_ops = &buf_ops_bio;
  933         bo->bo_private = vp;
  934         TAILQ_INIT(&bo->bo_clean.bv_hd);
  935         TAILQ_INIT(&bo->bo_dirty.bv_hd);
  936         /*
  937          * Initialize namecache.
  938          */
  939         LIST_INIT(&vp->v_cache_src);
  940         TAILQ_INIT(&vp->v_cache_dst);
  941         /*
  942          * Finalize various vnode identity bits.
  943          */
  944         vp->v_type = VNON;
  945         vp->v_tag = tag;
  946         vp->v_op = vops;
  947         v_incr_usecount(vp);
  948         vp->v_data = 0;
  949 #ifdef MAC
  950         mac_init_vnode(vp);
  951         if (mp != NULL && (mp->mnt_flag & MNT_MULTILABEL) == 0)
  952                 mac_associate_vnode_singlelabel(mp, vp);
  953         else if (mp == NULL)
  954                 printf("NULL mp in getnewvnode()\n");
  955 #endif
  956         if (mp != NULL) {
  957                 insmntque(vp, mp);
  958                 bo->bo_bsize = mp->mnt_stat.f_iosize;
  959                 if ((mp->mnt_kern_flag & MNTK_NOKNOTE) != 0)
  960                         vp->v_vflag |= VV_NOKNOTE;
  961         }
  962 
  963         CTR2(KTR_VFS, "getnewvnode: mp %p vp %p", mp, vp);
  964         *vpp = vp;
  965         return (0);
  966 }
  967 
  968 /*
  969  * Delete from old mount point vnode list, if on one.
  970  */
  971 static void
  972 delmntque(struct vnode *vp)
  973 {
  974         struct mount *mp;
  975 
  976         mp = vp->v_mount;
  977         if (mp == NULL)
  978                 return;
  979         MNT_ILOCK(mp);
  980         vp->v_mount = NULL;
  981         VNASSERT(mp->mnt_nvnodelistsize > 0, vp,
  982                 ("bad mount point vnode list size"));
  983         TAILQ_REMOVE(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
  984         mp->mnt_nvnodelistsize--;
  985         MNT_REL(mp);
  986         MNT_IUNLOCK(mp);
  987 }
  988 
  989 /*
  990  * Insert into list of vnodes for the new mount point, if available.
  991  */
  992 static void
  993 insmntque(struct vnode *vp, struct mount *mp)
  994 {
  995 
  996         vp->v_mount = mp;
  997         VNASSERT(mp != NULL, vp, ("Don't call insmntque(foo, NULL)"));
  998         MNT_ILOCK(mp);
  999         MNT_REF(mp);
 1000         TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
 1001         VNASSERT(mp->mnt_nvnodelistsize >= 0, vp,
 1002                 ("neg mount point vnode list size"));
 1003         mp->mnt_nvnodelistsize++;
 1004         MNT_IUNLOCK(mp);
 1005 }
 1006 
 1007 /*
 1008  * Flush out and invalidate all buffers associated with a bufobj
 1009  * Called with the underlying object locked.
 1010  */
 1011 int
 1012 bufobj_invalbuf(struct bufobj *bo, int flags, struct thread *td, int slpflag, int slptimeo)
 1013 {
 1014         int error;
 1015 
 1016         BO_LOCK(bo);
 1017         if (flags & V_SAVE) {
 1018                 error = bufobj_wwait(bo, slpflag, slptimeo);
 1019                 if (error) {
 1020                         BO_UNLOCK(bo);
 1021                         return (error);
 1022                 }
 1023                 if (bo->bo_dirty.bv_cnt > 0) {
 1024                         BO_UNLOCK(bo);
 1025                         if ((error = BO_SYNC(bo, MNT_WAIT, td)) != 0)
 1026                                 return (error);
 1027                         /*
 1028                          * XXX We could save a lock/unlock if this was only
 1029                          * enabled under INVARIANTS
 1030                          */
 1031                         BO_LOCK(bo);
 1032                         if (bo->bo_numoutput > 0 || bo->bo_dirty.bv_cnt > 0)
 1033                                 panic("vinvalbuf: dirty bufs");
 1034                 }
 1035         }
 1036         /*
 1037          * If you alter this loop please notice that interlock is dropped and
 1038          * reacquired in flushbuflist.  Special care is needed to ensure that
 1039          * no race conditions occur from this.
 1040          */
 1041         do {
 1042                 error = flushbuflist(&bo->bo_clean,
 1043                     flags, bo, slpflag, slptimeo);
 1044                 if (error == 0)
 1045                         error = flushbuflist(&bo->bo_dirty,
 1046                             flags, bo, slpflag, slptimeo);
 1047                 if (error != 0 && error != EAGAIN) {
 1048                         BO_UNLOCK(bo);
 1049                         return (error);
 1050                 }
 1051         } while (error != 0);
 1052 
 1053         /*
 1054          * Wait for I/O to complete.  XXX needs cleaning up.  The vnode can
 1055          * have write I/O in-progress but if there is a VM object then the
 1056          * VM object can also have read-I/O in-progress.
 1057          */
 1058         do {
 1059                 bufobj_wwait(bo, 0, 0);
 1060                 BO_UNLOCK(bo);
 1061                 if (bo->bo_object != NULL) {
 1062                         VM_OBJECT_LOCK(bo->bo_object);
 1063                         vm_object_pip_wait(bo->bo_object, "bovlbx");
 1064                         VM_OBJECT_UNLOCK(bo->bo_object);
 1065                 }
 1066                 BO_LOCK(bo);
 1067         } while (bo->bo_numoutput > 0);
 1068         BO_UNLOCK(bo);
 1069 
 1070         /*
 1071          * Destroy the copy in the VM cache, too.
 1072          */
 1073         if (bo->bo_object != NULL) {
 1074                 VM_OBJECT_LOCK(bo->bo_object);
 1075                 vm_object_page_remove(bo->bo_object, 0, 0,
 1076                         (flags & V_SAVE) ? TRUE : FALSE);
 1077                 VM_OBJECT_UNLOCK(bo->bo_object);
 1078         }
 1079 
 1080 #ifdef INVARIANTS
 1081         BO_LOCK(bo);
 1082         if ((flags & (V_ALT | V_NORMAL)) == 0 &&
 1083             (bo->bo_dirty.bv_cnt > 0 || bo->bo_clean.bv_cnt > 0))
 1084                 panic("vinvalbuf: flush failed");
 1085         BO_UNLOCK(bo);
 1086 #endif
 1087         return (0);
 1088 }
 1089 
 1090 /*
 1091  * Flush out and invalidate all buffers associated with a vnode.
 1092  * Called with the underlying object locked.
 1093  */
 1094 int
 1095 vinvalbuf(struct vnode *vp, int flags, struct thread *td, int slpflag, int slptimeo)
 1096 {
 1097 
 1098         CTR2(KTR_VFS, "vinvalbuf vp %p flags %d", vp, flags);
 1099         ASSERT_VOP_LOCKED(vp, "vinvalbuf");
 1100         return (bufobj_invalbuf(&vp->v_bufobj, flags, td, slpflag, slptimeo));
 1101 }
 1102 
 1103 /*
 1104  * Flush out buffers on the specified list.
 1105  *
 1106  */
 1107 static int
 1108 flushbuflist(bufv, flags, bo, slpflag, slptimeo)
 1109         struct bufv *bufv;
 1110         int flags;
 1111         struct bufobj *bo;
 1112         int slpflag, slptimeo;
 1113 {
 1114         struct buf *bp, *nbp;
 1115         int retval, error;
 1116         daddr_t lblkno;
 1117         b_xflags_t xflags;
 1118 
 1119         ASSERT_BO_LOCKED(bo);
 1120 
 1121         retval = 0;
 1122         TAILQ_FOREACH_SAFE(bp, &bufv->bv_hd, b_bobufs, nbp) {
 1123                 if (((flags & V_NORMAL) && (bp->b_xflags & BX_ALTDATA)) ||
 1124                     ((flags & V_ALT) && (bp->b_xflags & BX_ALTDATA) == 0)) {
 1125                         continue;
 1126                 }
 1127                 lblkno = 0;
 1128                 xflags = 0;
 1129                 if (nbp != NULL) {
 1130                         lblkno = nbp->b_lblkno;
 1131                         xflags = nbp->b_xflags &
 1132                                 (BX_BKGRDMARKER | BX_VNDIRTY | BX_VNCLEAN);
 1133                 }
 1134                 retval = EAGAIN;
 1135                 error = BUF_TIMELOCK(bp,
 1136                     LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK, BO_MTX(bo),
 1137                     "flushbuf", slpflag, slptimeo);
 1138                 if (error) {
 1139                         BO_LOCK(bo);
 1140                         return (error != ENOLCK ? error : EAGAIN);
 1141                 }
 1142                 KASSERT(bp->b_bufobj == bo,
 1143                     ("bp %p wrong b_bufobj %p should be %p",
 1144                     bp, bp->b_bufobj, bo));
 1145                 if (bp->b_bufobj != bo) {       /* XXX: necessary ? */
 1146                         BUF_UNLOCK(bp);
 1147                         BO_LOCK(bo);
 1148                         return (EAGAIN);
 1149                 }
 1150                 /*
 1151                  * XXX Since there are no node locks for NFS, I
 1152                  * believe there is a slight chance that a delayed
 1153                  * write will occur while sleeping just above, so
 1154                  * check for it.
 1155                  */
 1156                 if (((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) &&
 1157                     (flags & V_SAVE)) {
 1158                         bremfree(bp);
 1159                         bp->b_flags |= B_ASYNC;
 1160                         bwrite(bp);
 1161                         BO_LOCK(bo);
 1162                         return (EAGAIN);        /* XXX: why not loop ? */
 1163                 }
 1164                 bremfree(bp);
 1165                 bp->b_flags |= (B_INVAL | B_NOCACHE | B_RELBUF);
 1166                 bp->b_flags &= ~B_ASYNC;
 1167                 brelse(bp);
 1168                 BO_LOCK(bo);
 1169                 if (nbp != NULL &&
 1170                     (nbp->b_bufobj != bo || 
 1171                      nbp->b_lblkno != lblkno ||
 1172                      (nbp->b_xflags &
 1173                       (BX_BKGRDMARKER | BX_VNDIRTY | BX_VNCLEAN)) != xflags))
 1174                         break;                  /* nbp invalid */
 1175         }
 1176         return (retval);
 1177 }
 1178 
 1179 /*
 1180  * Truncate a file's buffer and pages to a specified length.  This
 1181  * is in lieu of the old vinvalbuf mechanism, which performed unneeded
 1182  * sync activity.
 1183  */
 1184 int
 1185 vtruncbuf(struct vnode *vp, struct ucred *cred, struct thread *td, off_t length, int blksize)
 1186 {
 1187         struct buf *bp, *nbp;
 1188         int anyfreed;
 1189         int trunclbn;
 1190         struct bufobj *bo;
 1191 
 1192         CTR2(KTR_VFS, "vtruncbuf vp %p length %jd", vp, length);
 1193         /*
 1194          * Round up to the *next* lbn.
 1195          */
 1196         trunclbn = (length + blksize - 1) / blksize;
 1197 
 1198         ASSERT_VOP_LOCKED(vp, "vtruncbuf");
 1199 restart:
 1200         VI_LOCK(vp);
 1201         bo = &vp->v_bufobj;
 1202         anyfreed = 1;
 1203         for (;anyfreed;) {
 1204                 anyfreed = 0;
 1205                 TAILQ_FOREACH_SAFE(bp, &bo->bo_clean.bv_hd, b_bobufs, nbp) {
 1206                         if (bp->b_lblkno < trunclbn)
 1207                                 continue;
 1208                         if (BUF_LOCK(bp,
 1209                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1210                             VI_MTX(vp)) == ENOLCK)
 1211                                 goto restart;
 1212 
 1213                         bremfree(bp);
 1214                         bp->b_flags |= (B_INVAL | B_RELBUF);
 1215                         bp->b_flags &= ~B_ASYNC;
 1216                         brelse(bp);
 1217                         anyfreed = 1;
 1218 
 1219                         if (nbp != NULL &&
 1220                             (((nbp->b_xflags & BX_VNCLEAN) == 0) ||
 1221                             (nbp->b_vp != vp) ||
 1222                             (nbp->b_flags & B_DELWRI))) {
 1223                                 goto restart;
 1224                         }
 1225                         VI_LOCK(vp);
 1226                 }
 1227 
 1228                 TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
 1229                         if (bp->b_lblkno < trunclbn)
 1230                                 continue;
 1231                         if (BUF_LOCK(bp,
 1232                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1233                             VI_MTX(vp)) == ENOLCK)
 1234                                 goto restart;
 1235                         bremfree(bp);
 1236                         bp->b_flags |= (B_INVAL | B_RELBUF);
 1237                         bp->b_flags &= ~B_ASYNC;
 1238                         brelse(bp);
 1239                         anyfreed = 1;
 1240                         if (nbp != NULL &&
 1241                             (((nbp->b_xflags & BX_VNDIRTY) == 0) ||
 1242                             (nbp->b_vp != vp) ||
 1243                             (nbp->b_flags & B_DELWRI) == 0)) {
 1244                                 goto restart;
 1245                         }
 1246                         VI_LOCK(vp);
 1247                 }
 1248         }
 1249 
 1250         if (length > 0) {
 1251 restartsync:
 1252                 TAILQ_FOREACH_SAFE(bp, &bo->bo_dirty.bv_hd, b_bobufs, nbp) {
 1253                         if (bp->b_lblkno > 0)
 1254                                 continue;
 1255                         /*
 1256                          * Since we hold the vnode lock this should only
 1257                          * fail if we're racing with the buf daemon.
 1258                          */
 1259                         if (BUF_LOCK(bp,
 1260                             LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK,
 1261                             VI_MTX(vp)) == ENOLCK) {
 1262                                 goto restart;
 1263                         }
 1264                         VNASSERT((bp->b_flags & B_DELWRI), vp,
 1265                             ("buf(%p) on dirty queue without DELWRI", bp));
 1266 
 1267                         bremfree(bp);
 1268                         bawrite(bp);
 1269                         VI_LOCK(vp);
 1270                         goto restartsync;
 1271                 }
 1272         }
 1273 
 1274         bufobj_wwait(bo, 0, 0);
 1275         VI_UNLOCK(vp);
 1276         vnode_pager_setsize(vp, length);
 1277 
 1278         return (0);
 1279 }
 1280 
 1281 /*
 1282  * buf_splay() - splay tree core for the clean/dirty list of buffers in
 1283  *               a vnode.
 1284  *
 1285  *      NOTE: We have to deal with the special case of a background bitmap
 1286  *      buffer, a situation where two buffers will have the same logical
 1287  *      block offset.  We want (1) only the foreground buffer to be accessed
 1288  *      in a lookup and (2) must differentiate between the foreground and
 1289  *      background buffer in the splay tree algorithm because the splay
 1290  *      tree cannot normally handle multiple entities with the same 'index'.
 1291  *      We accomplish this by adding differentiating flags to the splay tree's
 1292  *      numerical domain.
 1293  */
 1294 static
 1295 struct buf *
 1296 buf_splay(daddr_t lblkno, b_xflags_t xflags, struct buf *root)
 1297 {
 1298         struct buf dummy;
 1299         struct buf *lefttreemax, *righttreemin, *y;
 1300 
 1301         if (root == NULL)
 1302                 return (NULL);
 1303         lefttreemax = righttreemin = &dummy;
 1304         for (;;) {
 1305                 if (lblkno < root->b_lblkno ||
 1306                     (lblkno == root->b_lblkno &&
 1307                     (xflags & BX_BKGRDMARKER) < (root->b_xflags & BX_BKGRDMARKER))) {
 1308                         if ((y = root->b_left) == NULL)
 1309                                 break;
 1310                         if (lblkno < y->b_lblkno) {
 1311                                 /* Rotate right. */
 1312                                 root->b_left = y->b_right;
 1313                                 y->b_right = root;
 1314                                 root = y;
 1315                                 if ((y = root->b_left) == NULL)
 1316                                         break;
 1317                         }
 1318                         /* Link into the new root's right tree. */
 1319                         righttreemin->b_left = root;
 1320                         righttreemin = root;
 1321                 } else if (lblkno > root->b_lblkno ||
 1322                     (lblkno == root->b_lblkno &&
 1323                     (xflags & BX_BKGRDMARKER) > (root->b_xflags & BX_BKGRDMARKER))) {
 1324                         if ((y = root->b_right) == NULL)
 1325                                 break;
 1326                         if (lblkno > y->b_lblkno) {
 1327                                 /* Rotate left. */
 1328                                 root->b_right = y->b_left;
 1329                                 y->b_left = root;
 1330                                 root = y;
 1331                                 if ((y = root->b_right) == NULL)
 1332                                         break;
 1333                         }
 1334                         /* Link into the new root's left tree. */
 1335                         lefttreemax->b_right = root;
 1336                         lefttreemax = root;
 1337                 } else {
 1338                         break;
 1339                 }
 1340                 root = y;
 1341         }
 1342         /* Assemble the new root. */
 1343         lefttreemax->b_right = root->b_left;
 1344         righttreemin->b_left = root->b_right;
 1345         root->b_left = dummy.b_right;
 1346         root->b_right = dummy.b_left;
 1347         return (root);
 1348 }
 1349 
 1350 static void
 1351 buf_vlist_remove(struct buf *bp)
 1352 {
 1353         struct buf *root;
 1354         struct bufv *bv;
 1355 
 1356         KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp));
 1357         ASSERT_BO_LOCKED(bp->b_bufobj);
 1358         KASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) !=
 1359             (BX_VNDIRTY|BX_VNCLEAN),
 1360             ("buf_vlist_remove: Buf %p is on two lists", bp));
 1361         if (bp->b_xflags & BX_VNDIRTY) 
 1362                 bv = &bp->b_bufobj->bo_dirty;
 1363         else
 1364                 bv = &bp->b_bufobj->bo_clean;
 1365         if (bp != bv->bv_root) {
 1366                 root = buf_splay(bp->b_lblkno, bp->b_xflags, bv->bv_root);
 1367                 KASSERT(root == bp, ("splay lookup failed in remove"));
 1368         }
 1369         if (bp->b_left == NULL) {
 1370                 root = bp->b_right;
 1371         } else {
 1372                 root = buf_splay(bp->b_lblkno, bp->b_xflags, bp->b_left);
 1373                 root->b_right = bp->b_right;
 1374         }
 1375         bv->bv_root = root;
 1376         TAILQ_REMOVE(&bv->bv_hd, bp, b_bobufs);
 1377         bv->bv_cnt--;
 1378         bp->b_xflags &= ~(BX_VNDIRTY | BX_VNCLEAN);
 1379 }
 1380 
 1381 /*
 1382  * Add the buffer to the sorted clean or dirty block list using a
 1383  * splay tree algorithm.
 1384  *
 1385  * NOTE: xflags is passed as a constant, optimizing this inline function!
 1386  */
 1387 static void
 1388 buf_vlist_add(struct buf *bp, struct bufobj *bo, b_xflags_t xflags)
 1389 {
 1390         struct buf *root;
 1391         struct bufv *bv;
 1392 
 1393         ASSERT_BO_LOCKED(bo);
 1394         KASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) == 0,
 1395             ("buf_vlist_add: Buf %p has existing xflags %d", bp, bp->b_xflags));
 1396         bp->b_xflags |= xflags;
 1397         if (xflags & BX_VNDIRTY)
 1398                 bv = &bo->bo_dirty;
 1399         else
 1400                 bv = &bo->bo_clean;
 1401 
 1402         root = buf_splay(bp->b_lblkno, bp->b_xflags, bv->bv_root);
 1403         if (root == NULL) {
 1404                 bp->b_left = NULL;
 1405                 bp->b_right = NULL;
 1406                 TAILQ_INSERT_TAIL(&bv->bv_hd, bp, b_bobufs);
 1407         } else if (bp->b_lblkno < root->b_lblkno ||
 1408             (bp->b_lblkno == root->b_lblkno &&
 1409             (bp->b_xflags & BX_BKGRDMARKER) < (root->b_xflags & BX_BKGRDMARKER))) {
 1410                 bp->b_left = root->b_left;
 1411                 bp->b_right = root;
 1412                 root->b_left = NULL;
 1413                 TAILQ_INSERT_BEFORE(root, bp, b_bobufs);
 1414         } else {
 1415                 bp->b_right = root->b_right;
 1416                 bp->b_left = root;
 1417                 root->b_right = NULL;
 1418                 TAILQ_INSERT_AFTER(&bv->bv_hd, root, bp, b_bobufs);
 1419         }
 1420         bv->bv_cnt++;
 1421         bv->bv_root = bp;
 1422 }
 1423 
 1424 /*
 1425  * Lookup a buffer using the splay tree.  Note that we specifically avoid
 1426  * shadow buffers used in background bitmap writes.
 1427  *
 1428  * This code isn't quite efficient as it could be because we are maintaining
 1429  * two sorted lists and do not know which list the block resides in.
 1430  *
 1431  * During a "make buildworld" the desired buffer is found at one of
 1432  * the roots more than 60% of the time.  Thus, checking both roots
 1433  * before performing either splay eliminates unnecessary splays on the
 1434  * first tree splayed.
 1435  */
 1436 struct buf *
 1437 gbincore(struct bufobj *bo, daddr_t lblkno)
 1438 {
 1439         struct buf *bp;
 1440 
 1441         ASSERT_BO_LOCKED(bo);
 1442         if ((bp = bo->bo_clean.bv_root) != NULL &&
 1443             bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1444                 return (bp);
 1445         if ((bp = bo->bo_dirty.bv_root) != NULL &&
 1446             bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1447                 return (bp);
 1448         if ((bp = bo->bo_clean.bv_root) != NULL) {
 1449                 bo->bo_clean.bv_root = bp = buf_splay(lblkno, 0, bp);
 1450                 if (bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1451                         return (bp);
 1452         }
 1453         if ((bp = bo->bo_dirty.bv_root) != NULL) {
 1454                 bo->bo_dirty.bv_root = bp = buf_splay(lblkno, 0, bp);
 1455                 if (bp->b_lblkno == lblkno && !(bp->b_xflags & BX_BKGRDMARKER))
 1456                         return (bp);
 1457         }
 1458         return (NULL);
 1459 }
 1460 
 1461 /*
 1462  * Associate a buffer with a vnode.
 1463  */
 1464 void
 1465 bgetvp(struct vnode *vp, struct buf *bp)
 1466 {
 1467 
 1468         VNASSERT(bp->b_vp == NULL, bp->b_vp, ("bgetvp: not free"));
 1469 
 1470         CTR3(KTR_BUF, "bgetvp(%p) vp %p flags %X", bp, vp, bp->b_flags);
 1471         VNASSERT((bp->b_xflags & (BX_VNDIRTY|BX_VNCLEAN)) == 0, vp,
 1472             ("bgetvp: bp already attached! %p", bp));
 1473 
 1474         ASSERT_VI_LOCKED(vp, "bgetvp");
 1475         vholdl(vp);
 1476         bp->b_vp = vp;
 1477         bp->b_bufobj = &vp->v_bufobj;
 1478         /*
 1479          * Insert onto list for new vnode.
 1480          */
 1481         buf_vlist_add(bp, &vp->v_bufobj, BX_VNCLEAN);
 1482 }
 1483 
 1484 /*
 1485  * Disassociate a buffer from a vnode.
 1486  */
 1487 void
 1488 brelvp(struct buf *bp)
 1489 {
 1490         struct bufobj *bo;
 1491         struct vnode *vp;
 1492 
 1493         CTR3(KTR_BUF, "brelvp(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags);
 1494         KASSERT(bp->b_vp != NULL, ("brelvp: NULL"));
 1495 
 1496         /*
 1497          * Delete from old vnode list, if on one.
 1498          */
 1499         vp = bp->b_vp;          /* XXX */
 1500         bo = bp->b_bufobj;
 1501         BO_LOCK(bo);
 1502         if (bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN))
 1503                 buf_vlist_remove(bp);
 1504         else
 1505                 panic("brelvp: Buffer %p not on queue.", bp);
 1506         if ((bo->bo_flag & BO_ONWORKLST) && bo->bo_dirty.bv_cnt == 0) {
 1507                 bo->bo_flag &= ~BO_ONWORKLST;
 1508                 mtx_lock(&sync_mtx);
 1509                 LIST_REMOVE(bo, bo_synclist);
 1510                 syncer_worklist_len--;
 1511                 mtx_unlock(&sync_mtx);
 1512         }
 1513         bp->b_vp = NULL;
 1514         bp->b_bufobj = NULL;
 1515         vdropl(vp);
 1516 }
 1517 
 1518 /*
 1519  * Add an item to the syncer work queue.
 1520  */
 1521 static void
 1522 vn_syncer_add_to_worklist(struct bufobj *bo, int delay)
 1523 {
 1524         int slot;
 1525 
 1526         ASSERT_BO_LOCKED(bo);
 1527 
 1528         mtx_lock(&sync_mtx);
 1529         if (bo->bo_flag & BO_ONWORKLST)
 1530                 LIST_REMOVE(bo, bo_synclist);
 1531         else {
 1532                 bo->bo_flag |= BO_ONWORKLST;
 1533                 syncer_worklist_len++;
 1534         }
 1535 
 1536         if (delay > syncer_maxdelay - 2)
 1537                 delay = syncer_maxdelay - 2;
 1538         slot = (syncer_delayno + delay) & syncer_mask;
 1539 
 1540         LIST_INSERT_HEAD(&syncer_workitem_pending[slot], bo, bo_synclist);
 1541         mtx_unlock(&sync_mtx);
 1542 }
 1543 
 1544 static int
 1545 sysctl_vfs_worklist_len(SYSCTL_HANDLER_ARGS)
 1546 {
 1547         int error, len;
 1548 
 1549         mtx_lock(&sync_mtx);
 1550         len = syncer_worklist_len - sync_vnode_count;
 1551         mtx_unlock(&sync_mtx);
 1552         error = SYSCTL_OUT(req, &len, sizeof(len));
 1553         return (error);
 1554 }
 1555 
 1556 SYSCTL_PROC(_vfs, OID_AUTO, worklist_len, CTLTYPE_INT | CTLFLAG_RD, NULL, 0,
 1557     sysctl_vfs_worklist_len, "I", "Syncer thread worklist length");
 1558 
 1559 static struct proc *updateproc;
 1560 static void sched_sync(void);
 1561 static struct kproc_desc up_kp = {
 1562         "syncer",
 1563         sched_sync,
 1564         &updateproc
 1565 };
 1566 SYSINIT(syncer, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &up_kp)
 1567 
 1568 static int
 1569 sync_vnode(struct bufobj *bo, struct thread *td)
 1570 {
 1571         struct vnode *vp;
 1572         struct mount *mp;
 1573 
 1574         vp = bo->__bo_vnode;    /* XXX */
 1575         if (VOP_ISLOCKED(vp, NULL) != 0)
 1576                 return (1);
 1577         if (VI_TRYLOCK(vp) == 0)
 1578                 return (1);
 1579         /*
 1580          * We use vhold in case the vnode does not
 1581          * successfully sync.  vhold prevents the vnode from
 1582          * going away when we unlock the sync_mtx so that
 1583          * we can acquire the vnode interlock.
 1584          */
 1585         vholdl(vp);
 1586         mtx_unlock(&sync_mtx);
 1587         VI_UNLOCK(vp);
 1588         if (vn_start_write(vp, &mp, V_NOWAIT) != 0) {
 1589                 vdrop(vp);
 1590                 mtx_lock(&sync_mtx);
 1591                 return (1);
 1592         }
 1593         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
 1594         (void) VOP_FSYNC(vp, MNT_LAZY, td);
 1595         VOP_UNLOCK(vp, 0, td);
 1596         vn_finished_write(mp);
 1597         VI_LOCK(vp);
 1598         if ((bo->bo_flag & BO_ONWORKLST) != 0) {
 1599                 /*
 1600                  * Put us back on the worklist.  The worklist
 1601                  * routine will remove us from our current
 1602                  * position and then add us back in at a later
 1603                  * position.
 1604                  */
 1605                 vn_syncer_add_to_worklist(bo, syncdelay);
 1606         }
 1607         vdropl(vp);
 1608         mtx_lock(&sync_mtx);
 1609         return (0);
 1610 }
 1611 
 1612 /*
 1613  * System filesystem synchronizer daemon.
 1614  */
 1615 static void
 1616 sched_sync(void)
 1617 {
 1618         struct synclist *next;
 1619         struct synclist *slp;
 1620         struct bufobj *bo;
 1621         long starttime;
 1622         struct thread *td = FIRST_THREAD_IN_PROC(updateproc);
 1623         static int dummychan;
 1624         int last_work_seen;
 1625         int net_worklist_len;
 1626         int syncer_final_iter;
 1627         int first_printf;
 1628         int error;
 1629 
 1630         mtx_lock(&Giant);
 1631         last_work_seen = 0;
 1632         syncer_final_iter = 0;
 1633         first_printf = 1;
 1634         syncer_state = SYNCER_RUNNING;
 1635         starttime = time_second;
 1636         td->td_pflags |= TDP_NORUNNINGBUF;
 1637 
 1638         EVENTHANDLER_REGISTER(shutdown_pre_sync, syncer_shutdown, td->td_proc,
 1639             SHUTDOWN_PRI_LAST);
 1640 
 1641         for (;;) {
 1642                 mtx_lock(&sync_mtx);
 1643                 if (syncer_state == SYNCER_FINAL_DELAY &&
 1644                     syncer_final_iter == 0) {
 1645                         mtx_unlock(&sync_mtx);
 1646                         kthread_suspend_check(td->td_proc);
 1647                         mtx_lock(&sync_mtx);
 1648                 }
 1649                 net_worklist_len = syncer_worklist_len - sync_vnode_count;
 1650                 if (syncer_state != SYNCER_RUNNING &&
 1651                     starttime != time_second) {
 1652                         if (first_printf) {
 1653                                 printf("\nSyncing disks, vnodes remaining...");
 1654                                 first_printf = 0;
 1655                         }
 1656                         printf("%d ", net_worklist_len);
 1657                 }
 1658                 starttime = time_second;
 1659 
 1660                 /*
 1661                  * Push files whose dirty time has expired.  Be careful
 1662                  * of interrupt race on slp queue.
 1663                  *
 1664                  * Skip over empty worklist slots when shutting down.
 1665                  */
 1666                 do {
 1667                         slp = &syncer_workitem_pending[syncer_delayno];
 1668                         syncer_delayno += 1;
 1669                         if (syncer_delayno == syncer_maxdelay)
 1670                                 syncer_delayno = 0;
 1671                         next = &syncer_workitem_pending[syncer_delayno];
 1672                         /*
 1673                          * If the worklist has wrapped since the
 1674                          * it was emptied of all but syncer vnodes, 
 1675                          * switch to the FINAL_DELAY state and run
 1676                          * for one more second.
 1677                          */
 1678                         if (syncer_state == SYNCER_SHUTTING_DOWN &&
 1679                             net_worklist_len == 0 &&
 1680                             last_work_seen == syncer_delayno) {
 1681                                 syncer_state = SYNCER_FINAL_DELAY;
 1682                                 syncer_final_iter = SYNCER_SHUTDOWN_SPEEDUP;
 1683                         }
 1684                 } while (syncer_state != SYNCER_RUNNING && LIST_EMPTY(slp) &&
 1685                     syncer_worklist_len > 0);
 1686 
 1687                 /*
 1688                  * Keep track of the last time there was anything
 1689                  * on the worklist other than syncer vnodes.
 1690                  * Return to the SHUTTING_DOWN state if any
 1691                  * new work appears.
 1692                  */
 1693                 if (net_worklist_len > 0 || syncer_state == SYNCER_RUNNING)
 1694                         last_work_seen = syncer_delayno;
 1695                 if (net_worklist_len > 0 && syncer_state == SYNCER_FINAL_DELAY)
 1696                         syncer_state = SYNCER_SHUTTING_DOWN;
 1697                 while ((bo = LIST_FIRST(slp)) != NULL) {
 1698                         error = sync_vnode(bo, td);
 1699                         if (error == 1) {
 1700                                 LIST_REMOVE(bo, bo_synclist);
 1701                                 LIST_INSERT_HEAD(next, bo, bo_synclist);
 1702                                 continue;
 1703                         }
 1704                 }
 1705                 if (syncer_state == SYNCER_FINAL_DELAY && syncer_final_iter > 0)
 1706                         syncer_final_iter--;
 1707                 mtx_unlock(&sync_mtx);
 1708                 /*
 1709                  * The variable rushjob allows the kernel to speed up the
 1710                  * processing of the filesystem syncer process. A rushjob
 1711                  * value of N tells the filesystem syncer to process the next
 1712                  * N seconds worth of work on its queue ASAP. Currently rushjob
 1713                  * is used by the soft update code to speed up the filesystem
 1714                  * syncer process when the incore state is getting so far
 1715                  * ahead of the disk that the kernel memory pool is being
 1716                  * threatened with exhaustion.
 1717                  */
 1718                 mtx_lock(&sync_mtx);
 1719                 if (rushjob > 0) {
 1720                         rushjob -= 1;
 1721                         mtx_unlock(&sync_mtx);
 1722                         continue;
 1723                 }
 1724                 mtx_unlock(&sync_mtx);
 1725                 /*
 1726                  * Just sleep for a short period if time between
 1727                  * iterations when shutting down to allow some I/O
 1728                  * to happen.
 1729                  *
 1730                  * If it has taken us less than a second to process the
 1731                  * current work, then wait. Otherwise start right over
 1732                  * again. We can still lose time if any single round
 1733                  * takes more than two seconds, but it does not really
 1734                  * matter as we are just trying to generally pace the
 1735                  * filesystem activity.
 1736                  */
 1737                 if (syncer_state != SYNCER_RUNNING)
 1738                         tsleep(&dummychan, PPAUSE, "syncfnl",
 1739                             hz / SYNCER_SHUTDOWN_SPEEDUP);
 1740                 else if (time_second == starttime)
 1741                         tsleep(&lbolt, PPAUSE, "syncer", 0);
 1742         }
 1743 }
 1744 
 1745 /*
 1746  * Request the syncer daemon to speed up its work.
 1747  * We never push it to speed up more than half of its
 1748  * normal turn time, otherwise it could take over the cpu.
 1749  */
 1750 int
 1751 speedup_syncer()
 1752 {
 1753         struct thread *td;
 1754         int ret = 0;
 1755 
 1756         td = FIRST_THREAD_IN_PROC(updateproc);
 1757         sleepq_remove(td, &lbolt);
 1758         mtx_lock(&sync_mtx);
 1759         if (rushjob < syncdelay / 2) {
 1760                 rushjob += 1;
 1761                 stat_rush_requests += 1;
 1762                 ret = 1;
 1763         }
 1764         mtx_unlock(&sync_mtx);
 1765         return (ret);
 1766 }
 1767 
 1768 /*
 1769  * Tell the syncer to speed up its work and run though its work
 1770  * list several times, then tell it to shut down.
 1771  */
 1772 static void
 1773 syncer_shutdown(void *arg, int howto)
 1774 {
 1775         struct thread *td;
 1776 
 1777         if (howto & RB_NOSYNC)
 1778                 return;
 1779         td = FIRST_THREAD_IN_PROC(updateproc);
 1780         sleepq_remove(td, &lbolt);
 1781         mtx_lock(&sync_mtx);
 1782         syncer_state = SYNCER_SHUTTING_DOWN;
 1783         rushjob = 0;
 1784         mtx_unlock(&sync_mtx);
 1785         kproc_shutdown(arg, howto);
 1786 }
 1787 
 1788 /*
 1789  * Reassign a buffer from one vnode to another.
 1790  * Used to assign file specific control information
 1791  * (indirect blocks) to the vnode to which they belong.
 1792  */
 1793 void
 1794 reassignbuf(struct buf *bp)
 1795 {
 1796         struct vnode *vp;
 1797         struct bufobj *bo;
 1798         int delay;
 1799 #ifdef INVARIANTS
 1800         struct bufv *bv;
 1801 #endif
 1802 
 1803         vp = bp->b_vp;
 1804         bo = bp->b_bufobj;
 1805         ++reassignbufcalls;
 1806 
 1807         CTR3(KTR_BUF, "reassignbuf(%p) vp %p flags %X",
 1808             bp, bp->b_vp, bp->b_flags);
 1809         /*
 1810          * B_PAGING flagged buffers cannot be reassigned because their vp
 1811          * is not fully linked in.
 1812          */
 1813         if (bp->b_flags & B_PAGING)
 1814                 panic("cannot reassign paging buffer");
 1815 
 1816         /*
 1817          * Delete from old vnode list, if on one.
 1818          */
 1819         VI_LOCK(vp);
 1820         if (bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN))
 1821                 buf_vlist_remove(bp);
 1822         else
 1823                 panic("reassignbuf: Buffer %p not on queue.", bp);
 1824         /*
 1825          * If dirty, put on list of dirty buffers; otherwise insert onto list
 1826          * of clean buffers.
 1827          */
 1828         if (bp->b_flags & B_DELWRI) {
 1829                 if ((bo->bo_flag & BO_ONWORKLST) == 0) {
 1830                         switch (vp->v_type) {
 1831                         case VDIR:
 1832                                 delay = dirdelay;
 1833                                 break;
 1834                         case VCHR:
 1835                                 delay = metadelay;
 1836                                 break;
 1837                         default:
 1838                                 delay = filedelay;
 1839                         }
 1840                         vn_syncer_add_to_worklist(bo, delay);
 1841                 }
 1842                 buf_vlist_add(bp, bo, BX_VNDIRTY);
 1843         } else {
 1844                 buf_vlist_add(bp, bo, BX_VNCLEAN);
 1845 
 1846                 if ((bo->bo_flag & BO_ONWORKLST) && bo->bo_dirty.bv_cnt == 0) {
 1847                         mtx_lock(&sync_mtx);
 1848                         LIST_REMOVE(bo, bo_synclist);
 1849                         syncer_worklist_len--;
 1850                         mtx_unlock(&sync_mtx);
 1851                         bo->bo_flag &= ~BO_ONWORKLST;
 1852                 }
 1853         }
 1854 #ifdef INVARIANTS
 1855         bv = &bo->bo_clean;
 1856         bp = TAILQ_FIRST(&bv->bv_hd);
 1857         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1858             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1859         bp = TAILQ_LAST(&bv->bv_hd, buflists);
 1860         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1861             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1862         bv = &bo->bo_dirty;
 1863         bp = TAILQ_FIRST(&bv->bv_hd);
 1864         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1865             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1866         bp = TAILQ_LAST(&bv->bv_hd, buflists);
 1867         KASSERT(bp == NULL || bp->b_bufobj == bo,
 1868             ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo));
 1869 #endif
 1870         VI_UNLOCK(vp);
 1871 }
 1872 
 1873 /*
 1874  * Increment the use and hold counts on the vnode, taking care to reference
 1875  * the driver's usecount if this is a chardev.  The vholdl() will remove
 1876  * the vnode from the free list if it is presently free.  Requires the
 1877  * vnode interlock and returns with it held.
 1878  */
 1879 static void
 1880 v_incr_usecount(struct vnode *vp)
 1881 {
 1882 
 1883         CTR3(KTR_VFS, "v_incr_usecount: vp %p holdcnt %d usecount %d\n",
 1884             vp, vp->v_holdcnt, vp->v_usecount);
 1885         vp->v_usecount++;
 1886         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 1887                 dev_lock();
 1888                 vp->v_rdev->si_usecount++;
 1889                 dev_unlock();
 1890         }
 1891         vholdl(vp);
 1892 }
 1893 
 1894 /*
 1895  * Turn a holdcnt into a use+holdcnt such that only one call to
 1896  * v_decr_usecount is needed.
 1897  */
 1898 static void
 1899 v_upgrade_usecount(struct vnode *vp)
 1900 {
 1901 
 1902         CTR3(KTR_VFS, "v_upgrade_usecount: vp %p holdcnt %d usecount %d\n",
 1903             vp, vp->v_holdcnt, vp->v_usecount);
 1904         vp->v_usecount++;
 1905         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 1906                 dev_lock();
 1907                 vp->v_rdev->si_usecount++;
 1908                 dev_unlock();
 1909         }
 1910 }
 1911 
 1912 /*
 1913  * Decrement the vnode use and hold count along with the driver's usecount
 1914  * if this is a chardev.  The vdropl() below releases the vnode interlock
 1915  * as it may free the vnode.
 1916  */
 1917 static void
 1918 v_decr_usecount(struct vnode *vp)
 1919 {
 1920 
 1921         CTR3(KTR_VFS, "v_decr_usecount: vp %p holdcnt %d usecount %d\n",
 1922             vp, vp->v_holdcnt, vp->v_usecount);
 1923         ASSERT_VI_LOCKED(vp, __FUNCTION__);
 1924         VNASSERT(vp->v_usecount > 0, vp,
 1925             ("v_decr_usecount: negative usecount"));
 1926         vp->v_usecount--;
 1927         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 1928                 dev_lock();
 1929                 vp->v_rdev->si_usecount--;
 1930                 dev_unlock();
 1931         }
 1932         vdropl(vp);
 1933 }
 1934 
 1935 /*
 1936  * Decrement only the use count and driver use count.  This is intended to
 1937  * be paired with a follow on vdropl() to release the remaining hold count.
 1938  * In this way we may vgone() a vnode with a 0 usecount without risk of
 1939  * having it end up on a free list because the hold count is kept above 0.
 1940  */
 1941 static void
 1942 v_decr_useonly(struct vnode *vp)
 1943 {
 1944 
 1945         CTR3(KTR_VFS, "v_decr_useonly: vp %p holdcnt %d usecount %d\n",
 1946             vp, vp->v_holdcnt, vp->v_usecount);
 1947         ASSERT_VI_LOCKED(vp, __FUNCTION__);
 1948         VNASSERT(vp->v_usecount > 0, vp,
 1949             ("v_decr_useonly: negative usecount"));
 1950         vp->v_usecount--;
 1951         if (vp->v_type == VCHR && vp->v_rdev != NULL) {
 1952                 dev_lock();
 1953                 vp->v_rdev->si_usecount--;
 1954                 dev_unlock();
 1955         }
 1956 }
 1957 
 1958 /*
 1959  * Grab a particular vnode from the free list, increment its
 1960  * reference count and lock it. The vnode lock bit is set if the
 1961  * vnode is being eliminated in vgone. The process is awakened
 1962  * when the transition is completed, and an error returned to
 1963  * indicate that the vnode is no longer usable (possibly having
 1964  * been changed to a new filesystem type).
 1965  */
 1966 int
 1967 vget(struct vnode *vp, int flags, struct thread *td)
 1968 {
 1969         int oweinact;
 1970         int oldflags;
 1971         int error;
 1972 
 1973         error = 0;
 1974         oldflags = flags;
 1975         oweinact = 0;
 1976         VFS_ASSERT_GIANT(vp->v_mount);
 1977         if ((flags & LK_INTERLOCK) == 0)
 1978                 VI_LOCK(vp);
 1979         /*
 1980          * If the inactive call was deferred because vput() was called
 1981          * with a shared lock, we have to do it here before another thread
 1982          * gets a reference to data that should be dead.
 1983          */
 1984         if (vp->v_iflag & VI_OWEINACT) {
 1985                 if (flags & LK_NOWAIT) {
 1986                         VI_UNLOCK(vp);
 1987                         return (EBUSY);
 1988                 }
 1989                 flags &= ~LK_TYPE_MASK;
 1990                 flags |= LK_EXCLUSIVE;
 1991                 oweinact = 1;
 1992         }
 1993         vholdl(vp);
 1994         if ((error = vn_lock(vp, flags | LK_INTERLOCK, td)) != 0) {
 1995                 vdrop(vp);
 1996                 return (error);
 1997         }
 1998         VI_LOCK(vp);
 1999         /* Upgrade our holdcnt to a usecount. */
 2000         v_upgrade_usecount(vp);
 2001         if (vp->v_iflag & VI_DOOMED && (flags & LK_RETRY) == 0)
 2002                 panic("vget: vn_lock failed to return ENOENT\n");
 2003         if (oweinact) {
 2004                 if (vp->v_iflag & VI_OWEINACT)
 2005                         vinactive(vp, td);
 2006                 VI_UNLOCK(vp);
 2007                 if ((oldflags & LK_TYPE_MASK) == 0)
 2008                         VOP_UNLOCK(vp, 0, td);
 2009         } else
 2010                 VI_UNLOCK(vp);
 2011         return (0);
 2012 }
 2013 
 2014 /*
 2015  * Increase the reference count of a vnode.
 2016  */
 2017 void
 2018 vref(struct vnode *vp)
 2019 {
 2020 
 2021         VI_LOCK(vp);
 2022         v_incr_usecount(vp);
 2023         VI_UNLOCK(vp);
 2024 }
 2025 
 2026 /*
 2027  * Return reference count of a vnode.
 2028  *
 2029  * The results of this call are only guaranteed when some mechanism other
 2030  * than the VI lock is used to stop other processes from gaining references
 2031  * to the vnode.  This may be the case if the caller holds the only reference.
 2032  * This is also useful when stale data is acceptable as race conditions may
 2033  * be accounted for by some other means.
 2034  */
 2035 int
 2036 vrefcnt(struct vnode *vp)
 2037 {
 2038         int usecnt;
 2039 
 2040         VI_LOCK(vp);
 2041         usecnt = vp->v_usecount;
 2042         VI_UNLOCK(vp);
 2043 
 2044         return (usecnt);
 2045 }
 2046 
 2047 
 2048 /*
 2049  * Vnode put/release.
 2050  * If count drops to zero, call inactive routine and return to freelist.
 2051  */
 2052 void
 2053 vrele(vp)
 2054         struct vnode *vp;
 2055 {
 2056         struct thread *td = curthread;  /* XXX */
 2057 
 2058         KASSERT(vp != NULL, ("vrele: null vp"));
 2059         VFS_ASSERT_GIANT(vp->v_mount);
 2060 
 2061         VI_LOCK(vp);
 2062 
 2063         /* Skip this v_writecount check if we're going to panic below. */
 2064         VNASSERT(vp->v_writecount < vp->v_usecount || vp->v_usecount < 1, vp,
 2065             ("vrele: missed vn_close"));
 2066 
 2067         if (vp->v_usecount > 1 || ((vp->v_iflag & VI_DOINGINACT) &&
 2068             vp->v_usecount == 1)) {
 2069                 v_decr_usecount(vp);
 2070                 return;
 2071         }
 2072         if (vp->v_usecount != 1) {
 2073 #ifdef DIAGNOSTIC
 2074                 vprint("vrele: negative ref count", vp);
 2075 #endif
 2076                 VI_UNLOCK(vp);
 2077                 panic("vrele: negative ref cnt");
 2078         }
 2079         /*
 2080          * We want to hold the vnode until the inactive finishes to
 2081          * prevent vgone() races.  We drop the use count here and the
 2082          * hold count below when we're done.
 2083          */
 2084         v_decr_useonly(vp);
 2085         /*
 2086          * We must call VOP_INACTIVE with the node locked. Mark
 2087          * as VI_DOINGINACT to avoid recursion.
 2088          */
 2089         vp->v_iflag |= VI_OWEINACT;
 2090         if (vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK, td) == 0) {
 2091                 VI_LOCK(vp);
 2092                 if (vp->v_usecount > 0)
 2093                         vp->v_iflag &= ~VI_OWEINACT;
 2094                 if (vp->v_iflag & VI_OWEINACT)
 2095                         vinactive(vp, td);
 2096                 VOP_UNLOCK(vp, 0, td);
 2097         } else {
 2098                 VI_LOCK(vp);
 2099                 if (vp->v_usecount > 0)
 2100                         vp->v_iflag &= ~VI_OWEINACT;
 2101         }
 2102         vdropl(vp);
 2103 }
 2104 
 2105 /*
 2106  * Release an already locked vnode.  This give the same effects as
 2107  * unlock+vrele(), but takes less time and avoids releasing and
 2108  * re-aquiring the lock (as vrele() aquires the lock internally.)
 2109  */
 2110 void
 2111 vput(vp)
 2112         struct vnode *vp;
 2113 {
 2114         struct thread *td = curthread;  /* XXX */
 2115         int error;
 2116 
 2117         KASSERT(vp != NULL, ("vput: null vp"));
 2118         ASSERT_VOP_LOCKED(vp, "vput");
 2119         VFS_ASSERT_GIANT(vp->v_mount);
 2120         VI_LOCK(vp);
 2121         /* Skip this v_writecount check if we're going to panic below. */
 2122         VNASSERT(vp->v_writecount < vp->v_usecount || vp->v_usecount < 1, vp,
 2123             ("vput: missed vn_close"));
 2124         error = 0;
 2125 
 2126         if (vp->v_usecount > 1 || ((vp->v_iflag & VI_DOINGINACT) &&
 2127             vp->v_usecount == 1)) {
 2128                 VOP_UNLOCK(vp, 0, td);
 2129                 v_decr_usecount(vp);
 2130                 return;
 2131         }
 2132 
 2133         if (vp->v_usecount != 1) {
 2134 #ifdef DIAGNOSTIC
 2135                 vprint("vput: negative ref count", vp);
 2136 #endif
 2137                 panic("vput: negative ref cnt");
 2138         }
 2139         /*
 2140          * We want to hold the vnode until the inactive finishes to
 2141          * prevent vgone() races.  We drop the use count here and the
 2142          * hold count below when we're done.
 2143          */
 2144         v_decr_useonly(vp);
 2145         vp->v_iflag |= VI_OWEINACT;
 2146         if (VOP_ISLOCKED(vp, NULL) != LK_EXCLUSIVE) {
 2147                 error = VOP_LOCK(vp, LK_EXCLUPGRADE|LK_INTERLOCK|LK_NOWAIT, td);
 2148                 VI_LOCK(vp);
 2149                 if (error) {
 2150                         if (vp->v_usecount > 0)
 2151                                 vp->v_iflag &= ~VI_OWEINACT;
 2152                         goto done;
 2153                 }
 2154         }
 2155         if (vp->v_usecount > 0)
 2156                 vp->v_iflag &= ~VI_OWEINACT;
 2157         if (vp->v_iflag & VI_OWEINACT)
 2158                 vinactive(vp, td);
 2159         VOP_UNLOCK(vp, 0, td);
 2160 done:
 2161         vdropl(vp);
 2162 }
 2163 
 2164 /*
 2165  * Somebody doesn't want the vnode recycled.
 2166  */
 2167 void
 2168 vhold(struct vnode *vp)
 2169 {
 2170 
 2171         VI_LOCK(vp);
 2172         vholdl(vp);
 2173         VI_UNLOCK(vp);
 2174 }
 2175 
 2176 void
 2177 vholdl(struct vnode *vp)
 2178 {
 2179 
 2180         vp->v_holdcnt++;
 2181         if (VSHOULDBUSY(vp))
 2182                 vbusy(vp);
 2183 }
 2184 
 2185 /*
 2186  * Note that there is one less who cares about this vnode.  vdrop() is the
 2187  * opposite of vhold().
 2188  */
 2189 void
 2190 vdrop(struct vnode *vp)
 2191 {
 2192 
 2193         VI_LOCK(vp);
 2194         vdropl(vp);
 2195 }
 2196 
 2197 /*
 2198  * Drop the hold count of the vnode.  If this is the last reference to
 2199  * the vnode we will free it if it has been vgone'd otherwise it is
 2200  * placed on the free list.
 2201  */
 2202 static void
 2203 vdropl(struct vnode *vp)
 2204 {
 2205 
 2206         if (vp->v_holdcnt <= 0)
 2207                 panic("vdrop: holdcnt %d", vp->v_holdcnt);
 2208         vp->v_holdcnt--;
 2209         if (vp->v_holdcnt == 0) {
 2210                 if (vp->v_iflag & VI_DOOMED) {
 2211                         vdestroy(vp);
 2212                         return;
 2213                 } else
 2214                         vfree(vp);
 2215         }
 2216         VI_UNLOCK(vp);
 2217 }
 2218 
 2219 /*
 2220  * Call VOP_INACTIVE on the vnode and manage the DOINGINACT and OWEINACT
 2221  * flags.  DOINGINACT prevents us from recursing in calls to vinactive.
 2222  * OWEINACT tracks whether a vnode missed a call to inactive due to a
 2223  * failed lock upgrade.
 2224  */
 2225 static void
 2226 vinactive(struct vnode *vp, struct thread *td)
 2227 {
 2228 
 2229         ASSERT_VOP_LOCKED(vp, "vinactive");
 2230         ASSERT_VI_LOCKED(vp, "vinactive");
 2231         VNASSERT((vp->v_iflag & VI_DOINGINACT) == 0, vp,
 2232             ("vinactive: recursed on VI_DOINGINACT"));
 2233         vp->v_iflag |= VI_DOINGINACT;
 2234         vp->v_iflag &= ~VI_OWEINACT;
 2235         VI_UNLOCK(vp);
 2236         VOP_INACTIVE(vp, td);
 2237         VI_LOCK(vp);
 2238         VNASSERT(vp->v_iflag & VI_DOINGINACT, vp,
 2239             ("vinactive: lost VI_DOINGINACT"));
 2240         vp->v_iflag &= ~VI_DOINGINACT;
 2241 }
 2242 
 2243 /*
 2244  * Remove any vnodes in the vnode table belonging to mount point mp.
 2245  *
 2246  * If FORCECLOSE is not specified, there should not be any active ones,
 2247  * return error if any are found (nb: this is a user error, not a
 2248  * system error). If FORCECLOSE is specified, detach any active vnodes
 2249  * that are found.
 2250  *
 2251  * If WRITECLOSE is set, only flush out regular file vnodes open for
 2252  * writing.
 2253  *
 2254  * SKIPSYSTEM causes any vnodes marked VV_SYSTEM to be skipped.
 2255  *
 2256  * `rootrefs' specifies the base reference count for the root vnode
 2257  * of this filesystem. The root vnode is considered busy if its
 2258  * v_usecount exceeds this value. On a successful return, vflush(, td)
 2259  * will call vrele() on the root vnode exactly rootrefs times.
 2260  * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must
 2261  * be zero.
 2262  */
 2263 #ifdef DIAGNOSTIC
 2264 static int busyprt = 0;         /* print out busy vnodes */
 2265 SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, "");
 2266 #endif
 2267 
 2268 int
 2269 vflush(mp, rootrefs, flags, td)
 2270         struct mount *mp;
 2271         int rootrefs;
 2272         int flags;
 2273         struct thread *td;
 2274 {
 2275         struct vnode *vp, *mvp, *rootvp = NULL;
 2276         struct vattr vattr;
 2277         int busy = 0, error;
 2278 
 2279         CTR1(KTR_VFS, "vflush: mp %p", mp);
 2280         if (rootrefs > 0) {
 2281                 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0,
 2282                     ("vflush: bad args"));
 2283                 /*
 2284                  * Get the filesystem root vnode. We can vput() it
 2285                  * immediately, since with rootrefs > 0, it won't go away.
 2286                  */
 2287                 if ((error = VFS_ROOT(mp, LK_EXCLUSIVE, &rootvp, td)) != 0)
 2288                         return (error);
 2289                 vput(rootvp);
 2290 
 2291         }
 2292         MNT_ILOCK(mp);
 2293 loop:
 2294         MNT_VNODE_FOREACH(vp, mp, mvp) {
 2295 
 2296                 VI_LOCK(vp);
 2297                 vholdl(vp);
 2298                 MNT_IUNLOCK(mp);
 2299                 error = vn_lock(vp, LK_INTERLOCK | LK_EXCLUSIVE, td);
 2300                 if (error) {
 2301                         vdrop(vp);
 2302                         MNT_ILOCK(mp);
 2303                         MNT_VNODE_FOREACH_ABORT_ILOCKED(mp, mvp);
 2304                         goto loop;
 2305                 }
 2306                 /*
 2307                  * Skip over a vnodes marked VV_SYSTEM.
 2308                  */
 2309                 if ((flags & SKIPSYSTEM) && (vp->v_vflag & VV_SYSTEM)) {
 2310                         VOP_UNLOCK(vp, 0, td);
 2311                         vdrop(vp);
 2312                         MNT_ILOCK(mp);
 2313                         continue;
 2314                 }
 2315                 /*
 2316                  * If WRITECLOSE is set, flush out unlinked but still open
 2317                  * files (even if open only for reading) and regular file
 2318                  * vnodes open for writing.
 2319                  */
 2320                 if (flags & WRITECLOSE) {
 2321                         error = VOP_GETATTR(vp, &vattr, td->td_ucred, td);
 2322                         VI_LOCK(vp);
 2323 
 2324                         if ((vp->v_type == VNON ||
 2325                             (error == 0 && vattr.va_nlink > 0)) &&
 2326                             (vp->v_writecount == 0 || vp->v_type != VREG)) {
 2327                                 VOP_UNLOCK(vp, 0, td);
 2328                                 vdropl(vp);
 2329                                 MNT_ILOCK(mp);
 2330                                 continue;
 2331                         }
 2332                 } else
 2333                         VI_LOCK(vp);
 2334                 /*
 2335                  * With v_usecount == 0, all we need to do is clear out the
 2336                  * vnode data structures and we are done.
 2337                  *
 2338                  * If FORCECLOSE is set, forcibly close the vnode.
 2339                  */
 2340                 if (vp->v_usecount == 0 || (flags & FORCECLOSE)) {
 2341                         VNASSERT(vp->v_usecount == 0 ||
 2342                             (vp->v_type != VCHR && vp->v_type != VBLK), vp,
 2343                             ("device VNODE %p is FORCECLOSED", vp));
 2344                         vgonel(vp);
 2345                 } else {
 2346                         busy++;
 2347 #ifdef DIAGNOSTIC
 2348                         if (busyprt)
 2349                                 vprint("vflush: busy vnode", vp);
 2350 #endif
 2351                 }
 2352                 VOP_UNLOCK(vp, 0, td);
 2353                 vdropl(vp);
 2354                 MNT_ILOCK(mp);
 2355         }
 2356         MNT_IUNLOCK(mp);
 2357         if (rootrefs > 0 && (flags & FORCECLOSE) == 0) {
 2358                 /*
 2359                  * If just the root vnode is busy, and if its refcount
 2360                  * is equal to `rootrefs', then go ahead and kill it.
 2361                  */
 2362                 VI_LOCK(rootvp);
 2363                 KASSERT(busy > 0, ("vflush: not busy"));
 2364                 VNASSERT(rootvp->v_usecount >= rootrefs, rootvp,
 2365                     ("vflush: usecount %d < rootrefs %d",
 2366                      rootvp->v_usecount, rootrefs));
 2367                 if (busy == 1 && rootvp->v_usecount == rootrefs) {
 2368                         VOP_LOCK(rootvp, LK_EXCLUSIVE|LK_INTERLOCK, td);
 2369                         vgone(rootvp);
 2370                         VOP_UNLOCK(rootvp, 0, td);
 2371                         busy = 0;
 2372                 } else
 2373                         VI_UNLOCK(rootvp);
 2374         }
 2375         if (busy)
 2376                 return (EBUSY);
 2377         for (; rootrefs > 0; rootrefs--)
 2378                 vrele(rootvp);
 2379         return (0);
 2380 }
 2381 
 2382 /*
 2383  * Recycle an unused vnode to the front of the free list.
 2384  */
 2385 int
 2386 vrecycle(struct vnode *vp, struct thread *td)
 2387 {
 2388         int recycled;
 2389 
 2390         ASSERT_VOP_LOCKED(vp, "vrecycle");
 2391         recycled = 0;
 2392         VI_LOCK(vp);
 2393         if (vp->v_usecount == 0) {
 2394                 recycled = 1;
 2395                 vgonel(vp);
 2396         }
 2397         VI_UNLOCK(vp);
 2398         return (recycled);
 2399 }
 2400 
 2401 /*
 2402  * Eliminate all activity associated with a vnode
 2403  * in preparation for reuse.
 2404  */
 2405 void
 2406 vgone(struct vnode *vp)
 2407 {
 2408         VI_LOCK(vp);
 2409         vgonel(vp);
 2410         VI_UNLOCK(vp);
 2411 }
 2412 
 2413 /*
 2414  * vgone, with the vp interlock held.
 2415  */
 2416 void
 2417 vgonel(struct vnode *vp)
 2418 {
 2419         struct thread *td;
 2420         int oweinact;
 2421         int active;
 2422         struct mount *mp;
 2423 
 2424         CTR1(KTR_VFS, "vgonel: vp %p", vp);
 2425         ASSERT_VOP_LOCKED(vp, "vgonel");
 2426         ASSERT_VI_LOCKED(vp, "vgonel");
 2427 #if 0
 2428         /* XXX Need to fix ttyvp before I enable this. */
 2429         VNASSERT(vp->v_holdcnt, vp,
 2430             ("vgonel: vp %p has no reference.", vp));
 2431 #endif
 2432         td = curthread;
 2433 
 2434         /*
 2435          * Don't vgonel if we're already doomed.
 2436          */
 2437         if (vp->v_iflag & VI_DOOMED)
 2438                 return;
 2439         vp->v_iflag |= VI_DOOMED;
 2440         /*
 2441          * Check to see if the vnode is in use.  If so, we have to call
 2442          * VOP_CLOSE() and VOP_INACTIVE().
 2443          */
 2444         active = vp->v_usecount;
 2445         oweinact = (vp->v_iflag & VI_OWEINACT);
 2446         VI_UNLOCK(vp);
 2447         /*
 2448          * Clean out any buffers associated with the vnode.
 2449          * If the flush fails, just toss the buffers.
 2450          */
 2451         mp = NULL;
 2452         if (!TAILQ_EMPTY(&vp->v_bufobj.bo_dirty.bv_hd))
 2453                 (void) vn_start_secondary_write(vp, &mp, V_WAIT);
 2454         if (vinvalbuf(vp, V_SAVE, td, 0, 0) != 0)
 2455                 vinvalbuf(vp, 0, td, 0, 0);
 2456 
 2457         /*
 2458          * If purging an active vnode, it must be closed and
 2459          * deactivated before being reclaimed.
 2460          */
 2461         if (active)
 2462                 VOP_CLOSE(vp, FNONBLOCK, NOCRED, td);
 2463         if (oweinact || active) {
 2464                 VI_LOCK(vp);
 2465                 if ((vp->v_iflag & VI_DOINGINACT) == 0)
 2466                         vinactive(vp, td);
 2467                 VI_UNLOCK(vp);
 2468         }
 2469         /*
 2470          * Reclaim the vnode.
 2471          */
 2472         if (VOP_RECLAIM(vp, td))
 2473                 panic("vgone: cannot reclaim");
 2474         if (mp != NULL)
 2475                 vn_finished_secondary_write(mp);
 2476         VNASSERT(vp->v_object == NULL, vp,
 2477             ("vop_reclaim left v_object vp=%p, tag=%s", vp, vp->v_tag));
 2478         /*
 2479          * Delete from old mount point vnode list.
 2480          */
 2481         delmntque(vp);
 2482         cache_purge(vp);
 2483         /*
 2484          * Done with purge, reset to the standard lock and invalidate
 2485          * the vnode.
 2486          */
 2487         VI_LOCK(vp);
 2488         vp->v_vnlock = &vp->v_lock;
 2489         vp->v_op = &dead_vnodeops;
 2490         vp->v_tag = "none";
 2491         vp->v_type = VBAD;
 2492 }
 2493 
 2494 /*
 2495  * Calculate the total number of references to a special device.
 2496  */
 2497 int
 2498 vcount(vp)
 2499         struct vnode *vp;
 2500 {
 2501         int count;
 2502 
 2503         dev_lock();
 2504         count = vp->v_rdev->si_usecount;
 2505         dev_unlock();
 2506         return (count);
 2507 }
 2508 
 2509 /*
 2510  * Same as above, but using the struct cdev *as argument
 2511  */
 2512 int
 2513 count_dev(dev)
 2514         struct cdev *dev;
 2515 {
 2516         int count;
 2517 
 2518         dev_lock();
 2519         count = dev->si_usecount;
 2520         dev_unlock();
 2521         return(count);
 2522 }
 2523 
 2524 /*
 2525  * Print out a description of a vnode.
 2526  */
 2527 static char *typename[] =
 2528 {"VNON", "VREG", "VDIR", "VBLK", "VCHR", "VLNK", "VSOCK", "VFIFO", "VBAD",
 2529  "VMARKER"};
 2530 
 2531 void
 2532 vn_printf(struct vnode *vp, const char *fmt, ...)
 2533 {
 2534         va_list ap;
 2535         char buf[96];
 2536 
 2537         va_start(ap, fmt);
 2538         vprintf(fmt, ap);
 2539         va_end(ap);
 2540         printf("%p: ", (void *)vp);
 2541         printf("tag %s, type %s\n", vp->v_tag, typename[vp->v_type]);
 2542         printf("    usecount %d, writecount %d, refcount %d mountedhere %p\n",
 2543             vp->v_usecount, vp->v_writecount, vp->v_holdcnt, vp->v_mountedhere);
 2544         buf[0] = '\0';
 2545         buf[1] = '\0';
 2546         if (vp->v_vflag & VV_ROOT)
 2547                 strcat(buf, "|VV_ROOT");
 2548         if (vp->v_vflag & VV_TEXT)
 2549                 strcat(buf, "|VV_TEXT");
 2550         if (vp->v_vflag & VV_SYSTEM)
 2551                 strcat(buf, "|VV_SYSTEM");
 2552         if (vp->v_iflag & VI_DOOMED)
 2553                 strcat(buf, "|VI_DOOMED");
 2554         if (vp->v_iflag & VI_FREE)
 2555                 strcat(buf, "|VI_FREE");
 2556         printf("    flags (%s)\n", buf + 1);
 2557         if (mtx_owned(VI_MTX(vp)))
 2558                 printf(" VI_LOCKed");
 2559         if (vp->v_object != NULL)
 2560                 printf("    v_object %p ref %d pages %d\n",
 2561                     vp->v_object, vp->v_object->ref_count,
 2562                     vp->v_object->resident_page_count);
 2563         printf("    ");
 2564         lockmgr_printinfo(vp->v_vnlock);
 2565         printf("\n");
 2566         if (vp->v_data != NULL)
 2567                 VOP_PRINT(vp);
 2568 }
 2569 
 2570 #ifdef DDB
 2571 /*
 2572  * List all of the locked vnodes in the system.
 2573  * Called when debugging the kernel.
 2574  */
 2575 DB_SHOW_COMMAND(lockedvnods, lockedvnodes)
 2576 {
 2577         struct mount *mp, *nmp;
 2578         struct vnode *vp;
 2579 
 2580         /*
 2581          * Note: because this is DDB, we can't obey the locking semantics
 2582          * for these structures, which means we could catch an inconsistent
 2583          * state and dereference a nasty pointer.  Not much to be done
 2584          * about that.
 2585          */
 2586         printf("Locked vnodes\n");
 2587         for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp) {
 2588                 nmp = TAILQ_NEXT(mp, mnt_list);
 2589                 TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
 2590                         if (vp->v_type != VMARKER && VOP_ISLOCKED(vp, NULL))
 2591                                 vprint("", vp);
 2592                 }
 2593                 nmp = TAILQ_NEXT(mp, mnt_list);
 2594         }
 2595 }
 2596 
 2597 /*
 2598  * Show details about the given vnode.
 2599  */
 2600 DB_SHOW_COMMAND(vnode, db_show_vnode)
 2601 {
 2602         struct vnode *vp;
 2603 
 2604         if (!have_addr)
 2605                 return;
 2606         vp = (struct vnode *)addr;
 2607         vn_printf(vp, "vnode ");
 2608 }
 2609 #endif  /* DDB */
 2610 
 2611 /*
 2612  * Fill in a struct xvfsconf based on a struct vfsconf.
 2613  */
 2614 static void
 2615 vfsconf2x(struct vfsconf *vfsp, struct xvfsconf *xvfsp)
 2616 {
 2617 
 2618         strcpy(xvfsp->vfc_name, vfsp->vfc_name);
 2619         xvfsp->vfc_typenum = vfsp->vfc_typenum;
 2620         xvfsp->vfc_refcount = vfsp->vfc_refcount;
 2621         xvfsp->vfc_flags = vfsp->vfc_flags;
 2622         /*
 2623          * These are unused in userland, we keep them
 2624          * to not break binary compatibility.
 2625          */
 2626         xvfsp->vfc_vfsops = NULL;
 2627         xvfsp->vfc_next = NULL;
 2628 }
 2629 
 2630 /*
 2631  * Top level filesystem related information gathering.
 2632  */
 2633 static int
 2634 sysctl_vfs_conflist(SYSCTL_HANDLER_ARGS)
 2635 {
 2636         struct vfsconf *vfsp;
 2637         struct xvfsconf xvfsp;
 2638         int error;
 2639 
 2640         error = 0;
 2641         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
 2642                 bzero(&xvfsp, sizeof(xvfsp));
 2643                 vfsconf2x(vfsp, &xvfsp);
 2644                 error = SYSCTL_OUT(req, &xvfsp, sizeof xvfsp);
 2645                 if (error)
 2646                         break;
 2647         }
 2648         return (error);
 2649 }
 2650 
 2651 SYSCTL_PROC(_vfs, OID_AUTO, conflist, CTLFLAG_RD, NULL, 0, sysctl_vfs_conflist,
 2652     "S,xvfsconf", "List of all configured filesystems");
 2653 
 2654 #ifndef BURN_BRIDGES
 2655 static int      sysctl_ovfs_conf(SYSCTL_HANDLER_ARGS);
 2656 
 2657 static int
 2658 vfs_sysctl(SYSCTL_HANDLER_ARGS)
 2659 {
 2660         int *name = (int *)arg1 - 1;    /* XXX */
 2661         u_int namelen = arg2 + 1;       /* XXX */
 2662         struct vfsconf *vfsp;
 2663         struct xvfsconf xvfsp;
 2664 
 2665         printf("WARNING: userland calling deprecated sysctl, "
 2666             "please rebuild world\n");
 2667 
 2668 #if 1 || defined(COMPAT_PRELITE2)
 2669         /* Resolve ambiguity between VFS_VFSCONF and VFS_GENERIC. */
 2670         if (namelen == 1)
 2671                 return (sysctl_ovfs_conf(oidp, arg1, arg2, req));
 2672 #endif
 2673 
 2674         switch (name[1]) {
 2675         case VFS_MAXTYPENUM:
 2676                 if (namelen != 2)
 2677                         return (ENOTDIR);
 2678                 return (SYSCTL_OUT(req, &maxvfsconf, sizeof(int)));
 2679         case VFS_CONF:
 2680                 if (namelen != 3)
 2681                         return (ENOTDIR);       /* overloaded */
 2682                 TAILQ_FOREACH(vfsp, &vfsconf, vfc_list)
 2683                         if (vfsp->vfc_typenum == name[2])
 2684                                 break;
 2685                 if (vfsp == NULL)
 2686                         return (EOPNOTSUPP);
 2687                 bzero(&xvfsp, sizeof(xvfsp));
 2688                 vfsconf2x(vfsp, &xvfsp);
 2689                 return (SYSCTL_OUT(req, &xvfsp, sizeof(xvfsp)));
 2690         }
 2691         return (EOPNOTSUPP);
 2692 }
 2693 
 2694 static SYSCTL_NODE(_vfs, VFS_GENERIC, generic, CTLFLAG_RD | CTLFLAG_SKIP,
 2695         vfs_sysctl, "Generic filesystem");
 2696 
 2697 #if 1 || defined(COMPAT_PRELITE2)
 2698 
 2699 static int
 2700 sysctl_ovfs_conf(SYSCTL_HANDLER_ARGS)
 2701 {
 2702         int error;
 2703         struct vfsconf *vfsp;
 2704         struct ovfsconf ovfs;
 2705 
 2706         TAILQ_FOREACH(vfsp, &vfsconf, vfc_list) {
 2707                 bzero(&ovfs, sizeof(ovfs));
 2708                 ovfs.vfc_vfsops = vfsp->vfc_vfsops;     /* XXX used as flag */
 2709                 strcpy(ovfs.vfc_name, vfsp->vfc_name);
 2710                 ovfs.vfc_index = vfsp->vfc_typenum;
 2711                 ovfs.vfc_refcount = vfsp->vfc_refcount;
 2712                 ovfs.vfc_flags = vfsp->vfc_flags;
 2713                 error = SYSCTL_OUT(req, &ovfs, sizeof ovfs);
 2714                 if (error)
 2715                         return error;
 2716         }
 2717         return 0;
 2718 }
 2719 
 2720 #endif /* 1 || COMPAT_PRELITE2 */
 2721 #endif /* !BURN_BRIDGES */
 2722 
 2723 #define KINFO_VNODESLOP         10
 2724 #ifdef notyet
 2725 /*
 2726  * Dump vnode list (via sysctl).
 2727  */
 2728 /* ARGSUSED */
 2729 static int
 2730 sysctl_vnode(SYSCTL_HANDLER_ARGS)
 2731 {
 2732         struct xvnode *xvn;
 2733         struct thread *td = req->td;
 2734         struct mount *mp;
 2735         struct vnode *vp;
 2736         int error, len, n;
 2737 
 2738         /*
 2739          * Stale numvnodes access is not fatal here.
 2740          */
 2741         req->lock = 0;
 2742         len = (numvnodes + KINFO_VNODESLOP) * sizeof *xvn;
 2743         if (!req->oldptr)
 2744                 /* Make an estimate */
 2745                 return (SYSCTL_OUT(req, 0, len));
 2746 
 2747         error = sysctl_wire_old_buffer(req, 0);
 2748         if (error != 0)
 2749                 return (error);
 2750         xvn = malloc(len, M_TEMP, M_ZERO | M_WAITOK);
 2751         n = 0;
 2752         mtx_lock(&mountlist_mtx);
 2753         TAILQ_FOREACH(mp, &mountlist, mnt_list) {
 2754                 if (vfs_busy(mp, LK_NOWAIT, &mountlist_mtx, td))
 2755                         continue;
 2756                 MNT_ILOCK(mp);
 2757                 TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes) {
 2758                         if (n == len)
 2759                                 break;
 2760                         vref(vp);
 2761                         xvn[n].xv_size = sizeof *xvn;
 2762                         xvn[n].xv_vnode = vp;
 2763                         xvn[n].xv_id = 0;       /* XXX compat */
 2764 #define XV_COPY(field) xvn[n].xv_##field = vp->v_##field
 2765                         XV_COPY(usecount);
 2766                         XV_COPY(writecount);
 2767                         XV_COPY(holdcnt);
 2768                         XV_COPY(mount);
 2769                         XV_COPY(numoutput);
 2770                         XV_COPY(type);
 2771 #undef XV_COPY
 2772                         xvn[n].xv_flag = vp->v_vflag;
 2773 
 2774                         switch (vp->v_type) {
 2775                         case VREG:
 2776                         case VDIR:
 2777                         case VLNK:
 2778                                 break;
 2779                         case VBLK:
 2780                         case VCHR:
 2781                                 if (vp->v_rdev == NULL) {
 2782                                         vrele(vp);
 2783                                         continue;
 2784                                 }
 2785                                 xvn[n].xv_dev = dev2udev(vp->v_rdev);
 2786                                 break;
 2787                         case VSOCK:
 2788                                 xvn[n].xv_socket = vp->v_socket;
 2789                                 break;
 2790                         case VFIFO:
 2791                                 xvn[n].xv_fifo = vp->v_fifoinfo;
 2792                                 break;
 2793                         case VNON:
 2794                         case VBAD:
 2795                         default:
 2796                                 /* shouldn't happen? */
 2797                                 vrele(vp);
 2798                                 continue;
 2799                         }
 2800                         vrele(vp);
 2801                         ++n;
 2802                 }
 2803                 MNT_IUNLOCK(mp);
 2804                 mtx_lock(&mountlist_mtx);
 2805                 vfs_unbusy(mp, td);
 2806                 if (n == len)
 2807                         break;
 2808         }
 2809         mtx_unlock(&mountlist_mtx);
 2810 
 2811         error = SYSCTL_OUT(req, xvn, n * sizeof *xvn);
 2812         free(xvn, M_TEMP);
 2813         return (error);
 2814 }
 2815 
 2816 SYSCTL_PROC(_kern, KERN_VNODE, vnode, CTLTYPE_OPAQUE|CTLFLAG_RD,
 2817         0, 0, sysctl_vnode, "S,xvnode", "");
 2818 #endif
 2819 
 2820 /*
 2821  * Unmount all filesystems. The list is traversed in reverse order
 2822  * of mounting to avoid dependencies.
 2823  */
 2824 void
 2825 vfs_unmountall()
 2826 {
 2827         struct mount *mp;
 2828         struct thread *td;
 2829         int error;
 2830 
 2831         KASSERT(curthread != NULL, ("vfs_unmountall: NULL curthread"));
 2832         td = curthread;
 2833         /*
 2834          * Since this only runs when rebooting, it is not interlocked.
 2835          */
 2836         while(!TAILQ_EMPTY(&mountlist)) {
 2837                 mp = TAILQ_LAST(&mountlist, mntlist);
 2838                 error = dounmount(mp, MNT_FORCE, td);
 2839                 if (error) {
 2840                         TAILQ_REMOVE(&mountlist, mp, mnt_list);
 2841                         /*
 2842                          * XXX: Due to the way in which we mount the root
 2843                          * file system off of devfs, devfs will generate a
 2844                          * "busy" warning when we try to unmount it before
 2845                          * the root.  Don't print a warning as a result in
 2846                          * order to avoid false positive errors that may
 2847                          * cause needless upset.
 2848                          */
 2849                         if (strcmp(mp->mnt_vfc->vfc_name, "devfs") != 0) {
 2850                                 printf("unmount of %s failed (",
 2851                                     mp->mnt_stat.f_mntonname);
 2852                                 if (error == EBUSY)
 2853                                         printf("BUSY)\n");
 2854                                 else
 2855                                         printf("%d)\n", error);
 2856                         }
 2857                 } else {
 2858                         /* The unmount has removed mp from the mountlist */
 2859                 }
 2860         }
 2861 }
 2862 
 2863 /*
 2864  * perform msync on all vnodes under a mount point
 2865  * the mount point must be locked.
 2866  */
 2867 void
 2868 vfs_msync(struct mount *mp, int flags)
 2869 {
 2870         struct vnode *vp, *mvp;
 2871         struct vm_object *obj;
 2872 
 2873         MNT_ILOCK(mp);
 2874         MNT_VNODE_FOREACH(vp, mp, mvp) {
 2875                 VI_LOCK(vp);
 2876                 if ((vp->v_iflag & VI_OBJDIRTY) &&
 2877                     (flags == MNT_WAIT || VOP_ISLOCKED(vp, NULL) == 0)) {
 2878                         MNT_IUNLOCK(mp);
 2879                         if (!vget(vp,
 2880                             LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK,
 2881                             curthread)) {
 2882                                 if (vp->v_vflag & VV_NOSYNC) {  /* unlinked */
 2883                                         vput(vp);
 2884                                         MNT_ILOCK(mp);
 2885                                         continue;
 2886                                 }
 2887 
 2888                                 obj = vp->v_object;
 2889                                 if (obj != NULL) {
 2890                                         VM_OBJECT_LOCK(obj);
 2891                                         vm_object_page_clean(obj, 0, 0,
 2892                                             flags == MNT_WAIT ?
 2893                                             OBJPC_SYNC : OBJPC_NOSYNC);
 2894                                         VM_OBJECT_UNLOCK(obj);
 2895                                 }
 2896                                 vput(vp);
 2897                         }
 2898                         MNT_ILOCK(mp);
 2899                 } else
 2900                         VI_UNLOCK(vp);
 2901         }
 2902         MNT_IUNLOCK(mp);
 2903 }
 2904 
 2905 /*
 2906  * Mark a vnode as free, putting it up for recycling.
 2907  */
 2908 static void
 2909 vfree(struct vnode *vp)
 2910 {
 2911 
 2912         CTR1(KTR_VFS, "vfree vp %p", vp);
 2913         ASSERT_VI_LOCKED(vp, "vfree");
 2914         mtx_lock(&vnode_free_list_mtx);
 2915         VNASSERT(vp->v_op != NULL, vp, ("vfree: vnode already reclaimed."));
 2916         VNASSERT((vp->v_iflag & VI_FREE) == 0, vp, ("vnode already free"));
 2917         VNASSERT(VSHOULDFREE(vp), vp, ("vfree: freeing when we shouldn't"));
 2918         VNASSERT((vp->v_iflag & VI_DOOMED) == 0, vp,
 2919             ("vfree: Freeing doomed vnode"));
 2920         if (vp->v_iflag & VI_AGE) {
 2921                 TAILQ_INSERT_HEAD(&vnode_free_list, vp, v_freelist);
 2922         } else {
 2923                 TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
 2924         }
 2925         freevnodes++;
 2926         vp->v_iflag &= ~VI_AGE;
 2927         vp->v_iflag |= VI_FREE;
 2928         mtx_unlock(&vnode_free_list_mtx);
 2929 }
 2930 
 2931 /*
 2932  * Opposite of vfree() - mark a vnode as in use.
 2933  */
 2934 static void
 2935 vbusy(struct vnode *vp)
 2936 {
 2937         CTR1(KTR_VFS, "vbusy vp %p", vp);
 2938         ASSERT_VI_LOCKED(vp, "vbusy");
 2939         VNASSERT((vp->v_iflag & VI_FREE) != 0, vp, ("vnode not free"));
 2940         VNASSERT(vp->v_op != NULL, vp, ("vbusy: vnode already reclaimed."));
 2941 
 2942         mtx_lock(&vnode_free_list_mtx);
 2943         TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
 2944         freevnodes--;
 2945         vp->v_iflag &= ~(VI_FREE|VI_AGE);
 2946         mtx_unlock(&vnode_free_list_mtx);
 2947 }
 2948 
 2949 /*
 2950  * Initalize per-vnode helper structure to hold poll-related state.
 2951  */
 2952 void
 2953 v_addpollinfo(struct vnode *vp)
 2954 {
 2955         struct vpollinfo *vi;
 2956 
 2957         vi = uma_zalloc(vnodepoll_zone, M_WAITOK);
 2958         if (vp->v_pollinfo != NULL) {
 2959                 uma_zfree(vnodepoll_zone, vi);
 2960                 return;
 2961         }
 2962         vp->v_pollinfo = vi;
 2963         mtx_init(&vp->v_pollinfo->vpi_lock, "vnode pollinfo", NULL, MTX_DEF);
 2964         knlist_init(&vp->v_pollinfo->vpi_selinfo.si_note, vp, vfs_knllock,
 2965             vfs_knlunlock, vfs_knllocked);
 2966 }
 2967 
 2968 /*
 2969  * Record a process's interest in events which might happen to
 2970  * a vnode.  Because poll uses the historic select-style interface
 2971  * internally, this routine serves as both the ``check for any
 2972  * pending events'' and the ``record my interest in future events''
 2973  * functions.  (These are done together, while the lock is held,
 2974  * to avoid race conditions.)
 2975  */
 2976 int
 2977 vn_pollrecord(vp, td, events)
 2978         struct vnode *vp;
 2979         struct thread *td;
 2980         short events;
 2981 {
 2982 
 2983         if (vp->v_pollinfo == NULL)
 2984                 v_addpollinfo(vp);
 2985         mtx_lock(&vp->v_pollinfo->vpi_lock);
 2986         if (vp->v_pollinfo->vpi_revents & events) {
 2987                 /*
 2988                  * This leaves events we are not interested
 2989                  * in available for the other process which
 2990                  * which presumably had requested them
 2991                  * (otherwise they would never have been
 2992                  * recorded).
 2993                  */
 2994                 events &= vp->v_pollinfo->vpi_revents;
 2995                 vp->v_pollinfo->vpi_revents &= ~events;
 2996 
 2997                 mtx_unlock(&vp->v_pollinfo->vpi_lock);
 2998                 return events;
 2999         }
 3000         vp->v_pollinfo->vpi_events |= events;
 3001         selrecord(td, &vp->v_pollinfo->vpi_selinfo);
 3002         mtx_unlock(&vp->v_pollinfo->vpi_lock);
 3003         return 0;
 3004 }
 3005 
 3006 /*
 3007  * Routine to create and manage a filesystem syncer vnode.
 3008  */
 3009 #define sync_close ((int (*)(struct  vop_close_args *))nullop)
 3010 static int      sync_fsync(struct  vop_fsync_args *);
 3011 static int      sync_inactive(struct  vop_inactive_args *);
 3012 static int      sync_reclaim(struct  vop_reclaim_args *);
 3013 
 3014 static struct vop_vector sync_vnodeops = {
 3015         .vop_bypass =   VOP_EOPNOTSUPP,
 3016         .vop_close =    sync_close,             /* close */
 3017         .vop_fsync =    sync_fsync,             /* fsync */
 3018         .vop_inactive = sync_inactive,  /* inactive */
 3019         .vop_reclaim =  sync_reclaim,   /* reclaim */
 3020         .vop_lock =     vop_stdlock,    /* lock */
 3021         .vop_unlock =   vop_stdunlock,  /* unlock */
 3022         .vop_islocked = vop_stdislocked,        /* islocked */
 3023 };
 3024 
 3025 /*
 3026  * Create a new filesystem syncer vnode for the specified mount point.
 3027  */
 3028 int
 3029 vfs_allocate_syncvnode(mp)
 3030         struct mount *mp;
 3031 {
 3032         struct vnode *vp;
 3033         static long start, incr, next;
 3034         int error;
 3035 
 3036         /* Allocate a new vnode */
 3037         if ((error = getnewvnode("syncer", mp, &sync_vnodeops, &vp)) != 0) {
 3038                 mp->mnt_syncer = NULL;
 3039                 return (error);
 3040         }
 3041         vp->v_type = VNON;
 3042         /*
 3043          * Place the vnode onto the syncer worklist. We attempt to
 3044          * scatter them about on the list so that they will go off
 3045          * at evenly distributed times even if all the filesystems
 3046          * are mounted at once.
 3047          */
 3048         next += incr;
 3049         if (next == 0 || next > syncer_maxdelay) {
 3050                 start /= 2;
 3051                 incr /= 2;
 3052                 if (start == 0) {
 3053                         start = syncer_maxdelay / 2;
 3054                         incr = syncer_maxdelay;
 3055                 }
 3056                 next = start;
 3057         }
 3058         VI_LOCK(vp);
 3059         vn_syncer_add_to_worklist(&vp->v_bufobj,
 3060             syncdelay > 0 ? next % syncdelay : 0);
 3061         /* XXX - vn_syncer_add_to_worklist() also grabs and drops sync_mtx. */
 3062         mtx_lock(&sync_mtx);
 3063         sync_vnode_count++;
 3064         mtx_unlock(&sync_mtx);
 3065         VI_UNLOCK(vp);
 3066         mp->mnt_syncer = vp;
 3067         return (0);
 3068 }
 3069 
 3070 /*
 3071  * Do a lazy sync of the filesystem.
 3072  */
 3073 static int
 3074 sync_fsync(ap)
 3075         struct vop_fsync_args /* {
 3076                 struct vnode *a_vp;
 3077                 struct ucred *a_cred;
 3078                 int a_waitfor;
 3079                 struct thread *a_td;
 3080         } */ *ap;
 3081 {
 3082         struct vnode *syncvp = ap->a_vp;
 3083         struct mount *mp = syncvp->v_mount;
 3084         struct thread *td = ap->a_td;
 3085         int error, asyncflag;
 3086         struct bufobj *bo;
 3087 
 3088         /*
 3089          * We only need to do something if this is a lazy evaluation.
 3090          */
 3091         if (ap->a_waitfor != MNT_LAZY)
 3092                 return (0);
 3093 
 3094         /*
 3095          * Move ourselves to the back of the sync list.
 3096          */
 3097         bo = &syncvp->v_bufobj;
 3098         BO_LOCK(bo);
 3099         vn_syncer_add_to_worklist(bo, syncdelay);
 3100         BO_UNLOCK(bo);
 3101 
 3102         /*
 3103          * Walk the list of vnodes pushing all that are dirty and
 3104          * not already on the sync list.
 3105          */
 3106         mtx_lock(&mountlist_mtx);
 3107         if (vfs_busy(mp, LK_EXCLUSIVE | LK_NOWAIT, &mountlist_mtx, td) != 0) {
 3108                 mtx_unlock(&mountlist_mtx);
 3109                 return (0);
 3110         }
 3111         if (vn_start_write(NULL, &mp, V_NOWAIT) != 0) {
 3112                 vfs_unbusy(mp, td);
 3113                 return (0);
 3114         }
 3115         MNT_ILOCK(mp);
 3116         asyncflag = mp->mnt_flag & MNT_ASYNC;
 3117         mp->mnt_flag &= ~MNT_ASYNC;
 3118         MNT_IUNLOCK(mp);
 3119         vfs_msync(mp, MNT_NOWAIT);
 3120         error = VFS_SYNC(mp, MNT_LAZY, td);
 3121         MNT_ILOCK(mp);
 3122         if (asyncflag)
 3123                 mp->mnt_flag |= MNT_ASYNC;
 3124         MNT_IUNLOCK(mp);
 3125         vn_finished_write(mp);
 3126         vfs_unbusy(mp, td);
 3127         return (error);
 3128 }
 3129 
 3130 /*
 3131  * The syncer vnode is no referenced.
 3132  */
 3133 static int
 3134 sync_inactive(ap)
 3135         struct vop_inactive_args /* {
 3136                 struct vnode *a_vp;
 3137                 struct thread *a_td;
 3138         } */ *ap;
 3139 {
 3140 
 3141         vgone(ap->a_vp);
 3142         return (0);
 3143 }
 3144 
 3145 /*
 3146  * The syncer vnode is no longer needed and is being decommissioned.
 3147  *
 3148  * Modifications to the worklist must be protected by sync_mtx.
 3149  */
 3150 static int
 3151 sync_reclaim(ap)
 3152         struct vop_reclaim_args /* {
 3153                 struct vnode *a_vp;
 3154         } */ *ap;
 3155 {
 3156         struct vnode *vp = ap->a_vp;
 3157         struct bufobj *bo;
 3158 
 3159         VI_LOCK(vp);
 3160         bo = &vp->v_bufobj;
 3161         vp->v_mount->mnt_syncer = NULL;
 3162         if (bo->bo_flag & BO_ONWORKLST) {
 3163                 mtx_lock(&sync_mtx);
 3164                 LIST_REMOVE(bo, bo_synclist);
 3165                 syncer_worklist_len--;
 3166                 sync_vnode_count--;
 3167                 mtx_unlock(&sync_mtx);
 3168                 bo->bo_flag &= ~BO_ONWORKLST;
 3169         }
 3170         VI_UNLOCK(vp);
 3171 
 3172         return (0);
 3173 }
 3174 
 3175 /*
 3176  * Check if vnode represents a disk device
 3177  */
 3178 int
 3179 vn_isdisk(vp, errp)
 3180         struct vnode *vp;
 3181         int *errp;
 3182 {
 3183         int error;
 3184 
 3185         error = 0;
 3186         dev_lock();
 3187         if (vp->v_type != VCHR)
 3188                 error = ENOTBLK;
 3189         else if (vp->v_rdev == NULL)
 3190                 error = ENXIO;
 3191         else if (vp->v_rdev->si_devsw == NULL)
 3192                 error = ENXIO;
 3193         else if (!(vp->v_rdev->si_devsw->d_flags & D_DISK))
 3194                 error = ENOTBLK;
 3195         dev_unlock();
 3196         if (errp != NULL)
 3197                 *errp = error;
 3198         return (error == 0);
 3199 }
 3200 
 3201 /*
 3202  * Common filesystem object access control check routine.  Accepts a
 3203  * vnode's type, "mode", uid and gid, requested access mode, credentials,
 3204  * and optional call-by-reference privused argument allowing vaccess()
 3205  * to indicate to the caller whether privilege was used to satisfy the
 3206  * request (obsoleted).  Returns 0 on success, or an errno on failure.
 3207  */
 3208 int
 3209 vaccess(type, file_mode, file_uid, file_gid, acc_mode, cred, privused)
 3210         enum vtype type;
 3211         mode_t file_mode;
 3212         uid_t file_uid;
 3213         gid_t file_gid;
 3214         mode_t acc_mode;
 3215         struct ucred *cred;
 3216         int *privused;
 3217 {
 3218         mode_t dac_granted;
 3219 #ifdef CAPABILITIES
 3220         mode_t cap_granted;
 3221 #endif
 3222 
 3223         /*
 3224          * Look for a normal, non-privileged way to access the file/directory
 3225          * as requested.  If it exists, go with that.
 3226          */
 3227 
 3228         if (privused != NULL)
 3229                 *privused = 0;
 3230 
 3231         dac_granted = 0;
 3232 
 3233         /* Check the owner. */
 3234         if (cred->cr_uid == file_uid) {
 3235                 dac_granted |= VADMIN;
 3236                 if (file_mode & S_IXUSR)
 3237                         dac_granted |= VEXEC;
 3238                 if (file_mode & S_IRUSR)
 3239                         dac_granted |= VREAD;
 3240                 if (file_mode & S_IWUSR)
 3241                         dac_granted |= (VWRITE | VAPPEND);
 3242 
 3243                 if ((acc_mode & dac_granted) == acc_mode)
 3244                         return (0);
 3245 
 3246                 goto privcheck;
 3247         }
 3248 
 3249         /* Otherwise, check the groups (first match) */
 3250         if (groupmember(file_gid, cred)) {
 3251                 if (file_mode & S_IXGRP)
 3252                         dac_granted |= VEXEC;
 3253                 if (file_mode & S_IRGRP)
 3254                         dac_granted |= VREAD;
 3255                 if (file_mode & S_IWGRP)
 3256                         dac_granted |= (VWRITE | VAPPEND);
 3257 
 3258                 if ((acc_mode & dac_granted) == acc_mode)
 3259                         return (0);
 3260 
 3261                 goto privcheck;
 3262         }
 3263 
 3264         /* Otherwise, check everyone else. */
 3265         if (file_mode & S_IXOTH)
 3266                 dac_granted |= VEXEC;
 3267         if (file_mode & S_IROTH)
 3268                 dac_granted |= VREAD;
 3269         if (file_mode & S_IWOTH)
 3270                 dac_granted |= (VWRITE | VAPPEND);
 3271         if ((acc_mode & dac_granted) == acc_mode)
 3272                 return (0);
 3273 
 3274 privcheck:
 3275         if (!suser_cred(cred, SUSER_ALLOWJAIL)) {
 3276                 /* XXX audit: privilege used */
 3277                 if (privused != NULL)
 3278                         *privused = 1;
 3279                 return (0);
 3280         }
 3281 
 3282 #ifdef CAPABILITIES
 3283         /*
 3284          * Build a capability mask to determine if the set of capabilities
 3285          * satisfies the requirements when combined with the granted mask
 3286          * from above.
 3287          * For each capability, if the capability is required, bitwise
 3288          * or the request type onto the cap_granted mask.
 3289          */
 3290         cap_granted = 0;
 3291 
 3292         if (type == VDIR) {
 3293                 /*
 3294                  * For directories, use CAP_DAC_READ_SEARCH to satisfy
 3295                  * VEXEC requests, instead of CAP_DAC_EXECUTE.
 3296                  */
 3297                 if ((acc_mode & VEXEC) && ((dac_granted & VEXEC) == 0) &&
 3298                     !cap_check(cred, NULL, CAP_DAC_READ_SEARCH, SUSER_ALLOWJAIL))
 3299                         cap_granted |= VEXEC;
 3300         } else {
 3301                 if ((acc_mode & VEXEC) && ((dac_granted & VEXEC) == 0) &&
 3302                     !cap_check(cred, NULL, CAP_DAC_EXECUTE, SUSER_ALLOWJAIL))
 3303                         cap_granted |= VEXEC;
 3304         }
 3305 
 3306         if ((acc_mode & VREAD) && ((dac_granted & VREAD) == 0) &&
 3307             !cap_check(cred, NULL, CAP_DAC_READ_SEARCH, SUSER_ALLOWJAIL))
 3308                 cap_granted |= VREAD;
 3309 
 3310         if ((acc_mode & VWRITE) && ((dac_granted & VWRITE) == 0) &&
 3311             !cap_check(cred, NULL, CAP_DAC_WRITE, SUSER_ALLOWJAIL))
 3312                 cap_granted |= (VWRITE | VAPPEND);
 3313 
 3314         if ((acc_mode & VADMIN) && ((dac_granted & VADMIN) == 0) &&
 3315             !cap_check(cred, NULL, CAP_FOWNER, SUSER_ALLOWJAIL))
 3316                 cap_granted |= VADMIN;
 3317 
 3318         if ((acc_mode & (cap_granted | dac_granted)) == acc_mode) {
 3319                 /* XXX audit: privilege used */
 3320                 if (privused != NULL)
 3321                         *privused = 1;
 3322                 return (0);
 3323         }
 3324 #endif
 3325 
 3326         return ((acc_mode & VADMIN) ? EPERM : EACCES);
 3327 }
 3328 
 3329 /*
 3330  * Credential check based on process requesting service, and per-attribute
 3331  * permissions.
 3332  */
 3333 int
 3334 extattr_check_cred(struct vnode *vp, int attrnamespace,
 3335     struct ucred *cred, struct thread *td, int access)
 3336 {
 3337 
 3338         /*
 3339          * Kernel-invoked always succeeds.
 3340          */
 3341         if (cred == NOCRED)
 3342                 return (0);
 3343 
 3344         /*
 3345          * Do not allow privileged processes in jail to directly
 3346          * manipulate system attributes.
 3347          *
 3348          * XXX What capability should apply here?
 3349          * Probably CAP_SYS_SETFFLAG.
 3350          */
 3351         switch (attrnamespace) {
 3352         case EXTATTR_NAMESPACE_SYSTEM:
 3353                 /* Potentially should be: return (EPERM); */
 3354                 return (suser_cred(cred, 0));
 3355         case EXTATTR_NAMESPACE_USER:
 3356                 return (VOP_ACCESS(vp, access, cred, td));
 3357         default:
 3358                 return (EPERM);
 3359         }
 3360 }
 3361 
 3362 #ifdef DEBUG_VFS_LOCKS
 3363 /*
 3364  * This only exists to supress warnings from unlocked specfs accesses.  It is
 3365  * no longer ok to have an unlocked VFS.
 3366  */
 3367 #define IGNORE_LOCK(vp) ((vp)->v_type == VCHR || (vp)->v_type == VBAD)
 3368 
 3369 int vfs_badlock_ddb = 1;        /* Drop into debugger on violation. */
 3370 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_ddb, CTLFLAG_RW, &vfs_badlock_ddb, 0, "");
 3371 
 3372 int vfs_badlock_mutex = 1;      /* Check for interlock across VOPs. */
 3373 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_mutex, CTLFLAG_RW, &vfs_badlock_mutex, 0, "");
 3374 
 3375 int vfs_badlock_print = 1;      /* Print lock violations. */
 3376 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_print, CTLFLAG_RW, &vfs_badlock_print, 0, "");
 3377 
 3378 #ifdef KDB
 3379 int vfs_badlock_backtrace = 1;  /* Print backtrace at lock violations. */
 3380 SYSCTL_INT(_debug, OID_AUTO, vfs_badlock_backtrace, CTLFLAG_RW, &vfs_badlock_backtrace, 0, "");
 3381 #endif
 3382 
 3383 static void
 3384 vfs_badlock(const char *msg, const char *str, struct vnode *vp)
 3385 {
 3386 
 3387 #ifdef KDB
 3388         if (vfs_badlock_backtrace)
 3389                 kdb_backtrace();
 3390 #endif
 3391         if (vfs_badlock_print)
 3392                 printf("%s: %p %s\n", str, (void *)vp, msg);
 3393         if (vfs_badlock_ddb)
 3394                 kdb_enter("lock violation");
 3395 }
 3396 
 3397 void
 3398 assert_vi_locked(struct vnode *vp, const char *str)
 3399 {
 3400 
 3401         if (vfs_badlock_mutex && !mtx_owned(VI_MTX(vp)))
 3402                 vfs_badlock("interlock is not locked but should be", str, vp);
 3403 }
 3404 
 3405 void
 3406 assert_vi_unlocked(struct vnode *vp, const char *str)
 3407 {
 3408 
 3409         if (vfs_badlock_mutex && mtx_owned(VI_MTX(vp)))
 3410                 vfs_badlock("interlock is locked but should not be", str, vp);
 3411 }
 3412 
 3413 void
 3414 assert_vop_locked(struct vnode *vp, const char *str)
 3415 {
 3416 
 3417         if (vp && !IGNORE_LOCK(vp) && VOP_ISLOCKED(vp, NULL) == 0)
 3418                 vfs_badlock("is not locked but should be", str, vp);
 3419 }
 3420 
 3421 void
 3422 assert_vop_unlocked(struct vnode *vp, const char *str)
 3423 {
 3424 
 3425         if (vp && !IGNORE_LOCK(vp) &&
 3426             VOP_ISLOCKED(vp, curthread) == LK_EXCLUSIVE)
 3427                 vfs_badlock("is locked but should not be", str, vp);
 3428 }
 3429 
 3430 void
 3431 assert_vop_elocked(struct vnode *vp, const char *str)
 3432 {
 3433 
 3434         if (vp && !IGNORE_LOCK(vp) &&
 3435             VOP_ISLOCKED(vp, curthread) != LK_EXCLUSIVE)
 3436                 vfs_badlock("is not exclusive locked but should be", str, vp);
 3437 }
 3438 
 3439 #if 0
 3440 void
 3441 assert_vop_elocked_other(struct vnode *vp, const char *str)
 3442 {
 3443 
 3444         if (vp && !IGNORE_LOCK(vp) &&
 3445             VOP_ISLOCKED(vp, curthread) != LK_EXCLOTHER)
 3446                 vfs_badlock("is not exclusive locked by another thread",
 3447                     str, vp);
 3448 }
 3449 
 3450 void
 3451 assert_vop_slocked(struct vnode *vp, const char *str)
 3452 {
 3453 
 3454         if (vp && !IGNORE_LOCK(vp) &&
 3455             VOP_ISLOCKED(vp, curthread) != LK_SHARED)
 3456                 vfs_badlock("is not locked shared but should be", str, vp);
 3457 }
 3458 #endif /* 0 */
 3459 #endif /* DEBUG_VFS_LOCKS */
 3460 
 3461 void
 3462 vop_rename_pre(void *ap)
 3463 {
 3464         struct vop_rename_args *a = ap;
 3465 
 3466 #ifdef DEBUG_VFS_LOCKS
 3467         if (a->a_tvp)
 3468                 ASSERT_VI_UNLOCKED(a->a_tvp, "VOP_RENAME");
 3469         ASSERT_VI_UNLOCKED(a->a_tdvp, "VOP_RENAME");
 3470         ASSERT_VI_UNLOCKED(a->a_fvp, "VOP_RENAME");
 3471         ASSERT_VI_UNLOCKED(a->a_fdvp, "VOP_RENAME");
 3472 
 3473         /* Check the source (from). */
 3474         if (a->a_tdvp != a->a_fdvp)
 3475                 ASSERT_VOP_UNLOCKED(a->a_fdvp, "vop_rename: fdvp locked");
 3476         if (a->a_tvp != a->a_fvp)
 3477                 ASSERT_VOP_UNLOCKED(a->a_fvp, "vop_rename: tvp locked");
 3478 
 3479         /* Check the target. */
 3480         if (a->a_tvp)
 3481                 ASSERT_VOP_LOCKED(a->a_tvp, "vop_rename: tvp not locked");
 3482         ASSERT_VOP_LOCKED(a->a_tdvp, "vop_rename: tdvp not locked");
 3483 #endif
 3484         if (a->a_tdvp != a->a_fdvp)
 3485                 vhold(a->a_fdvp);
 3486         if (a->a_tvp != a->a_fvp)
 3487                 vhold(a->a_fvp);
 3488         vhold(a->a_tdvp);
 3489         if (a->a_tvp)
 3490                 vhold(a->a_tvp);
 3491 }
 3492 
 3493 void
 3494 vop_strategy_pre(void *ap)
 3495 {
 3496 #ifdef DEBUG_VFS_LOCKS
 3497         struct vop_strategy_args *a;
 3498         struct buf *bp;
 3499 
 3500         a = ap;
 3501         bp = a->a_bp;
 3502 
 3503         /*
 3504          * Cluster ops lock their component buffers but not the IO container.
 3505          */
 3506         if ((bp->b_flags & B_CLUSTER) != 0)
 3507                 return;
 3508 
 3509         if (BUF_REFCNT(bp) < 1) {
 3510                 if (vfs_badlock_print)
 3511                         printf(
 3512                             "VOP_STRATEGY: bp is not locked but should be\n");
 3513                 if (vfs_badlock_ddb)
 3514                         kdb_enter("lock violation");
 3515         }
 3516 #endif
 3517 }
 3518 
 3519 void
 3520 vop_lookup_pre(void *ap)
 3521 {
 3522 #ifdef DEBUG_VFS_LOCKS
 3523         struct vop_lookup_args *a;
 3524         struct vnode *dvp;
 3525 
 3526         a = ap;
 3527         dvp = a->a_dvp;
 3528         ASSERT_VI_UNLOCKED(dvp, "VOP_LOOKUP");
 3529         ASSERT_VOP_LOCKED(dvp, "VOP_LOOKUP");
 3530 #endif
 3531 }
 3532 
 3533 void
 3534 vop_lookup_post(void *ap, int rc)
 3535 {
 3536 #ifdef DEBUG_VFS_LOCKS
 3537         struct vop_lookup_args *a;
 3538         struct vnode *dvp;
 3539         struct vnode *vp;
 3540 
 3541         a = ap;
 3542         dvp = a->a_dvp;
 3543         vp = *(a->a_vpp);
 3544 
 3545         ASSERT_VI_UNLOCKED(dvp, "VOP_LOOKUP");
 3546         ASSERT_VOP_LOCKED(dvp, "VOP_LOOKUP");
 3547 
 3548         if (!rc)
 3549                 ASSERT_VOP_LOCKED(vp, "VOP_LOOKUP (child)");
 3550 #endif
 3551 }
 3552 
 3553 void
 3554 vop_lock_pre(void *ap)
 3555 {
 3556 #ifdef DEBUG_VFS_LOCKS
 3557         struct vop_lock_args *a = ap;
 3558 
 3559         if ((a->a_flags & LK_INTERLOCK) == 0)
 3560                 ASSERT_VI_UNLOCKED(a->a_vp, "VOP_LOCK");
 3561         else
 3562                 ASSERT_VI_LOCKED(a->a_vp, "VOP_LOCK");
 3563 #endif
 3564 }
 3565 
 3566 void
 3567 vop_lock_post(void *ap, int rc)
 3568 {
 3569 #ifdef DEBUG_VFS_LOCKS
 3570         struct vop_lock_args *a = ap;
 3571 
 3572         ASSERT_VI_UNLOCKED(a->a_vp, "VOP_LOCK");
 3573         if (rc == 0)
 3574                 ASSERT_VOP_LOCKED(a->a_vp, "VOP_LOCK");
 3575 #endif
 3576 }
 3577 
 3578 void
 3579 vop_unlock_pre(void *ap)
 3580 {
 3581 #ifdef DEBUG_VFS_LOCKS
 3582         struct vop_unlock_args *a = ap;
 3583 
 3584         if (a->a_flags & LK_INTERLOCK)
 3585                 ASSERT_VI_LOCKED(a->a_vp, "VOP_UNLOCK");
 3586         ASSERT_VOP_LOCKED(a->a_vp, "VOP_UNLOCK");
 3587 #endif
 3588 }
 3589 
 3590 void
 3591 vop_unlock_post(void *ap, int rc)
 3592 {
 3593 #ifdef DEBUG_VFS_LOCKS
 3594         struct vop_unlock_args *a = ap;
 3595 
 3596         if (a->a_flags & LK_INTERLOCK)
 3597                 ASSERT_VI_UNLOCKED(a->a_vp, "VOP_UNLOCK");
 3598 #endif
 3599 }
 3600 
 3601 void
 3602 vop_create_post(void *ap, int rc)
 3603 {
 3604         struct vop_create_args *a = ap;
 3605 
 3606         if (!rc)
 3607                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE); 
 3608 }
 3609 
 3610 void
 3611 vop_link_post(void *ap, int rc)
 3612 {
 3613         struct vop_link_args *a = ap;
 3614         
 3615         if (!rc) {
 3616                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_LINK); 
 3617                 VFS_KNOTE_LOCKED(a->a_tdvp, NOTE_WRITE);
 3618         }
 3619 }
 3620 
 3621 void
 3622 vop_mkdir_post(void *ap, int rc)
 3623 {
 3624         struct vop_mkdir_args *a = ap;
 3625 
 3626         if (!rc)
 3627                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE | NOTE_LINK);
 3628 }
 3629 
 3630 void
 3631 vop_mknod_post(void *ap, int rc)
 3632 {
 3633         struct vop_mknod_args *a = ap;
 3634 
 3635         if (!rc)
 3636                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 3637 }
 3638 
 3639 void
 3640 vop_remove_post(void *ap, int rc)
 3641 {
 3642         struct vop_remove_args *a = ap;
 3643 
 3644         if (!rc) {
 3645                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 3646                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_DELETE);
 3647         }
 3648 }
 3649 
 3650 void
 3651 vop_rename_post(void *ap, int rc)
 3652 {
 3653         struct vop_rename_args *a = ap;
 3654 
 3655         if (!rc) {
 3656                 VFS_KNOTE_UNLOCKED(a->a_fdvp, NOTE_WRITE);
 3657                 VFS_KNOTE_UNLOCKED(a->a_tdvp, NOTE_WRITE);
 3658                 VFS_KNOTE_UNLOCKED(a->a_fvp, NOTE_RENAME);
 3659                 if (a->a_tvp)
 3660                         VFS_KNOTE_UNLOCKED(a->a_tvp, NOTE_DELETE);
 3661         }
 3662         if (a->a_tdvp != a->a_fdvp)
 3663                 vdrop(a->a_fdvp);
 3664         if (a->a_tvp != a->a_fvp)
 3665                 vdrop(a->a_fvp);
 3666         vdrop(a->a_tdvp);
 3667         if (a->a_tvp)
 3668                 vdrop(a->a_tvp);
 3669 }
 3670 
 3671 void
 3672 vop_rmdir_post(void *ap, int rc)
 3673 {
 3674         struct vop_rmdir_args *a = ap;
 3675 
 3676         if (!rc) {
 3677                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE | NOTE_LINK);
 3678                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_DELETE);
 3679         }
 3680 }
 3681 
 3682 void
 3683 vop_setattr_post(void *ap, int rc)
 3684 {
 3685         struct vop_setattr_args *a = ap;
 3686 
 3687         if (!rc)
 3688                 VFS_KNOTE_LOCKED(a->a_vp, NOTE_ATTRIB);
 3689 }
 3690 
 3691 void
 3692 vop_symlink_post(void *ap, int rc)
 3693 {
 3694         struct vop_symlink_args *a = ap;
 3695         
 3696         if (!rc)
 3697                 VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
 3698 }
 3699 
 3700 static struct knlist fs_knlist;
 3701 
 3702 static void
 3703 vfs_event_init(void *arg)
 3704 {
 3705         knlist_init(&fs_knlist, NULL, NULL, NULL, NULL);
 3706 }
 3707 /* XXX - correct order? */
 3708 SYSINIT(vfs_knlist, SI_SUB_VFS, SI_ORDER_ANY, vfs_event_init, NULL);
 3709 
 3710 void
 3711 vfs_event_signal(fsid_t *fsid, u_int32_t event, intptr_t data __unused)
 3712 {
 3713 
 3714         KNOTE_UNLOCKED(&fs_knlist, event);
 3715 }
 3716 
 3717 static int      filt_fsattach(struct knote *kn);
 3718 static void     filt_fsdetach(struct knote *kn);
 3719 static int      filt_fsevent(struct knote *kn, long hint);
 3720 
 3721 struct filterops fs_filtops =
 3722         { 0, filt_fsattach, filt_fsdetach, filt_fsevent };
 3723 
 3724 static int
 3725 filt_fsattach(struct knote *kn)
 3726 {
 3727 
 3728         kn->kn_flags |= EV_CLEAR;
 3729         knlist_add(&fs_knlist, kn, 0);
 3730         return (0);
 3731 }
 3732 
 3733 static void
 3734 filt_fsdetach(struct knote *kn)
 3735 {
 3736 
 3737         knlist_remove(&fs_knlist, kn, 0);
 3738 }
 3739 
 3740 static int
 3741 filt_fsevent(struct knote *kn, long hint)
 3742 {
 3743 
 3744         kn->kn_fflags |= hint;
 3745         return (kn->kn_fflags != 0);
 3746 }
 3747 
 3748 static int
 3749 sysctl_vfs_ctl(SYSCTL_HANDLER_ARGS)
 3750 {
 3751         struct vfsidctl vc;
 3752         int error;
 3753         struct mount *mp;
 3754 
 3755         error = SYSCTL_IN(req, &vc, sizeof(vc));
 3756         if (error)
 3757                 return (error);
 3758         if (vc.vc_vers != VFS_CTL_VERS1)
 3759                 return (EINVAL);
 3760         mp = vfs_getvfs(&vc.vc_fsid);
 3761         if (mp == NULL)
 3762                 return (ENOENT);
 3763         /* ensure that a specific sysctl goes to the right filesystem. */
 3764         if (strcmp(vc.vc_fstypename, "*") != 0 &&
 3765             strcmp(vc.vc_fstypename, mp->mnt_vfc->vfc_name) != 0) {
 3766                 vfs_rel(mp);
 3767                 return (EINVAL);
 3768         }
 3769         VCTLTOREQ(&vc, req);
 3770         error = VFS_SYSCTL(mp, vc.vc_op, req);
 3771         vfs_rel(mp);
 3772         return (error);
 3773 }
 3774 
 3775 SYSCTL_PROC(_vfs, OID_AUTO, ctl, CTLFLAG_WR,
 3776         NULL, 0, sysctl_vfs_ctl, "", "Sysctl by fsid");
 3777 
 3778 /*
 3779  * Function to initialize a va_filerev field sensibly.
 3780  * XXX: Wouldn't a random number make a lot more sense ??
 3781  */
 3782 u_quad_t
 3783 init_va_filerev(void)
 3784 {
 3785         struct bintime bt;
 3786 
 3787         getbinuptime(&bt);
 3788         return (((u_quad_t)bt.sec << 32LL) | (bt.frac >> 32LL));
 3789 }
 3790 
 3791 static int      filt_vfsread(struct knote *kn, long hint);
 3792 static int      filt_vfswrite(struct knote *kn, long hint);
 3793 static int      filt_vfsvnode(struct knote *kn, long hint);
 3794 static void     filt_vfsdetach(struct knote *kn);
 3795 static struct filterops vfsread_filtops =
 3796         { 1, NULL, filt_vfsdetach, filt_vfsread };
 3797 static struct filterops vfswrite_filtops =
 3798         { 1, NULL, filt_vfsdetach, filt_vfswrite };
 3799 static struct filterops vfsvnode_filtops =
 3800         { 1, NULL, filt_vfsdetach, filt_vfsvnode };
 3801 
 3802 static void
 3803 vfs_knllock(void *arg)
 3804 {
 3805         struct vnode *vp = arg;
 3806 
 3807         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, curthread);
 3808 }
 3809 
 3810 static void
 3811 vfs_knlunlock(void *arg)
 3812 {
 3813         struct vnode *vp = arg;
 3814 
 3815         VOP_UNLOCK(vp, 0, curthread);
 3816 }
 3817 
 3818 static int
 3819 vfs_knllocked(void *arg)
 3820 {
 3821         struct vnode *vp = arg;
 3822 
 3823         return (VOP_ISLOCKED(vp, curthread) == LK_EXCLUSIVE);
 3824 }
 3825 
 3826 int
 3827 vfs_kqfilter(struct vop_kqfilter_args *ap)
 3828 {
 3829         struct vnode *vp = ap->a_vp;
 3830         struct knote *kn = ap->a_kn;
 3831         struct knlist *knl; 
 3832 
 3833         switch (kn->kn_filter) {
 3834         case EVFILT_READ:
 3835                 kn->kn_fop = &vfsread_filtops;
 3836                 break;
 3837         case EVFILT_WRITE:
 3838                 kn->kn_fop = &vfswrite_filtops;
 3839                 break;
 3840         case EVFILT_VNODE:
 3841                 kn->kn_fop = &vfsvnode_filtops;
 3842                 break;
 3843         default:
 3844                 return (EINVAL);
 3845         }
 3846 
 3847         kn->kn_hook = (caddr_t)vp;
 3848 
 3849         if (vp->v_pollinfo == NULL)
 3850                 v_addpollinfo(vp);
 3851         if (vp->v_pollinfo == NULL)
 3852                 return (ENOMEM);
 3853         knl = &vp->v_pollinfo->vpi_selinfo.si_note;
 3854         knlist_add(knl, kn, 0);
 3855 
 3856         return (0);
 3857 }
 3858 
 3859 /*
 3860  * Detach knote from vnode
 3861  */
 3862 static void
 3863 filt_vfsdetach(struct knote *kn)
 3864 {
 3865         struct vnode *vp = (struct vnode *)kn->kn_hook;
 3866 
 3867         KASSERT(vp->v_pollinfo != NULL, ("Missing v_pollinfo"));
 3868         knlist_remove(&vp->v_pollinfo->vpi_selinfo.si_note, kn, 0);
 3869 }
 3870 
 3871 /*ARGSUSED*/
 3872 static int
 3873 filt_vfsread(struct knote *kn, long hint)
 3874 {
 3875         struct vnode *vp = (struct vnode *)kn->kn_hook;
 3876         struct vattr va;
 3877 
 3878         /*
 3879          * filesystem is gone, so set the EOF flag and schedule
 3880          * the knote for deletion.
 3881          */
 3882         if (hint == NOTE_REVOKE) {
 3883                 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 3884                 return (1);
 3885         }
 3886 
 3887         if (VOP_GETATTR(vp, &va, curthread->td_ucred, curthread)) 
 3888                 return (0);
 3889 
 3890         kn->kn_data = va.va_size - kn->kn_fp->f_offset;
 3891         return (kn->kn_data != 0);
 3892 }
 3893 
 3894 /*ARGSUSED*/
 3895 static int
 3896 filt_vfswrite(struct knote *kn, long hint)
 3897 {
 3898         /*
 3899          * filesystem is gone, so set the EOF flag and schedule
 3900          * the knote for deletion.
 3901          */
 3902         if (hint == NOTE_REVOKE)
 3903                 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
 3904 
 3905         kn->kn_data = 0;
 3906         return (1);
 3907 }
 3908 
 3909 static int
 3910 filt_vfsvnode(struct knote *kn, long hint)
 3911 {
 3912         if (kn->kn_sfflags & hint)
 3913                 kn->kn_fflags |= hint;
 3914         if (hint == NOTE_REVOKE) {
 3915                 kn->kn_flags |= EV_EOF;
 3916                 return (1);
 3917         }
 3918         return (kn->kn_fflags != 0);
 3919 }
 3920 
 3921 int
 3922 vfs_read_dirent(struct vop_readdir_args *ap, struct dirent *dp, off_t off)
 3923 {
 3924         int error;
 3925 
 3926         if (dp->d_reclen > ap->a_uio->uio_resid)
 3927                 return (ENAMETOOLONG);
 3928         error = uiomove(dp, dp->d_reclen, ap->a_uio);
 3929         if (error) {
 3930                 if (ap->a_ncookies != NULL) {
 3931                         if (ap->a_cookies != NULL)
 3932                                 free(ap->a_cookies, M_TEMP);
 3933                         ap->a_cookies = NULL;
 3934                         *ap->a_ncookies = 0;
 3935                 }
 3936                 return (error);
 3937         }
 3938         if (ap->a_ncookies == NULL)
 3939                 return (0);
 3940 
 3941         KASSERT(ap->a_cookies,
 3942             ("NULL ap->a_cookies value with non-NULL ap->a_ncookies!"));
 3943 
 3944         *ap->a_cookies = realloc(*ap->a_cookies,
 3945             (*ap->a_ncookies + 1) * sizeof(u_long), M_TEMP, M_WAITOK | M_ZERO);
 3946         (*ap->a_cookies)[*ap->a_ncookies] = off;
 3947         return (0);
 3948 }
 3949 
 3950 /*
 3951  * Mark for update the access time of the file if the filesystem
 3952  * supports VA_MARK_ATIME.  This functionality is used by execve
 3953  * and mmap, so we want to avoid the synchronous I/O implied by
 3954  * directly setting va_atime for the sake of efficiency.
 3955  */
 3956 void
 3957 vfs_mark_atime(struct vnode *vp, struct thread *td)
 3958 {
 3959         struct vattr atimeattr;
 3960 
 3961         if ((vp->v_mount->mnt_flag & (MNT_NOATIME | MNT_RDONLY)) == 0) {
 3962                 VATTR_NULL(&atimeattr);
 3963                 atimeattr.va_vaflags |= VA_MARK_ATIME;
 3964                 (void)VOP_SETATTR(vp, &atimeattr, td->td_ucred, td);
 3965         }
 3966 }

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