2 * Copyright (c) 2004 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
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18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
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22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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34 * Copyright (c) 1989, 1993
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36 * (c) UNIX System Laboratories, Inc.
37 * All or some portions of this file are derived from material licensed
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55 * may be used to endorse or promote products derived from this software
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65 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
66 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
67 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
70 * $DragonFly: src/sys/kern/vfs_mount.c,v 1.37 2008/09/17 21:44:18 dillon Exp $
74 * External virtual filesystem routines
78 #include <sys/param.h>
79 #include <sys/systm.h>
80 #include <sys/kernel.h>
81 #include <sys/malloc.h>
82 #include <sys/mount.h>
84 #include <sys/vnode.h>
86 #include <sys/eventhandler.h>
87 #include <sys/kthread.h>
88 #include <sys/sysctl.h>
90 #include <machine/limits.h>
93 #include <sys/thread2.h>
94 #include <sys/sysref2.h>
97 #include <vm/vm_object.h>
99 struct mountscan_info {
100 TAILQ_ENTRY(mountscan_info) msi_entry;
102 struct mount *msi_node;
105 struct vmntvnodescan_info {
106 TAILQ_ENTRY(vmntvnodescan_info) entry;
114 static int vnlru_nowhere = 0;
115 SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RD,
117 "Number of times the vnlru process ran without success");
120 static struct lwkt_token mntid_token;
122 /* note: mountlist exported to pstat */
123 struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist);
124 static TAILQ_HEAD(,mountscan_info) mountscan_list;
125 static struct lwkt_token mountlist_token;
126 static TAILQ_HEAD(,vmntvnodescan_info) mntvnodescan_list;
127 struct lwkt_token mntvnode_token;
129 static TAILQ_HEAD(,bio_ops) bio_ops_list = TAILQ_HEAD_INITIALIZER(bio_ops_list);
132 * Called from vfsinit()
137 lwkt_token_init(&mountlist_token);
138 lwkt_token_init(&mntvnode_token);
139 lwkt_token_init(&mntid_token);
140 TAILQ_INIT(&mountscan_list);
141 TAILQ_INIT(&mntvnodescan_list);
145 * Support function called with mntvnode_token held to remove a vnode
146 * from the mountlist. We must update any list scans which are in progress.
149 vremovevnodemnt(struct vnode *vp)
151 struct vmntvnodescan_info *info;
153 TAILQ_FOREACH(info, &mntvnodescan_list, entry) {
155 info->vp = TAILQ_NEXT(vp, v_nmntvnodes);
157 TAILQ_REMOVE(&vp->v_mount->mnt_nvnodelist, vp, v_nmntvnodes);
161 * Allocate a new vnode and associate it with a tag, mount point, and
164 * A VX locked and refd vnode is returned. The caller should setup the
165 * remaining fields and vx_put() or, if he wishes to leave a vref,
166 * vx_unlock() the vnode.
169 getnewvnode(enum vtagtype tag, struct mount *mp,
170 struct vnode **vpp, int lktimeout, int lkflags)
174 KKASSERT(mp != NULL);
176 vp = allocvnode(lktimeout, lkflags);
181 * By default the vnode is assigned the mount point's normal
184 vp->v_ops = &mp->mnt_vn_use_ops;
187 * Placing the vnode on the mount point's queue makes it visible.
188 * VNON prevents it from being messed with, however.
193 * A VX locked & refd vnode is returned.
200 * This function creates vnodes with special operations vectors. The
201 * mount point is optional.
203 * This routine is being phased out.
206 getspecialvnode(enum vtagtype tag, struct mount *mp,
207 struct vop_ops **ops,
208 struct vnode **vpp, int lktimeout, int lkflags)
212 vp = allocvnode(lktimeout, lkflags);
218 * Placing the vnode on the mount point's queue makes it visible.
219 * VNON prevents it from being messed with, however.
224 * A VX locked & refd vnode is returned.
231 * Interlock against an unmount, return 0 on success, non-zero on failure.
233 * The passed flag may be 0 or LK_NOWAIT and is only used if an unmount
236 * If no unmount is in-progress LK_NOWAIT is ignored. No other flag bits
237 * are used. A shared locked will be obtained and the filesystem will not
238 * be unmountable until the lock is released.
241 vfs_busy(struct mount *mp, int flags)
245 if (mp->mnt_kern_flag & MNTK_UNMOUNT) {
246 if (flags & LK_NOWAIT)
248 /* XXX not MP safe */
249 mp->mnt_kern_flag |= MNTK_MWAIT;
251 * Since all busy locks are shared except the exclusive
252 * lock granted when unmounting, the only place that a
253 * wakeup needs to be done is at the release of the
254 * exclusive lock at the end of dounmount.
256 tsleep((caddr_t)mp, 0, "vfs_busy", 0);
260 if (lockmgr(&mp->mnt_lock, lkflags))
261 panic("vfs_busy: unexpected lock failure");
266 * Free a busy filesystem.
269 vfs_unbusy(struct mount *mp)
271 lockmgr(&mp->mnt_lock, LK_RELEASE);
275 * Lookup a filesystem type, and if found allocate and initialize
276 * a mount structure for it.
278 * Devname is usually updated by mount(8) after booting.
281 vfs_rootmountalloc(char *fstypename, char *devname, struct mount **mpp)
283 struct vfsconf *vfsp;
286 if (fstypename == NULL)
289 vfsp = vfsconf_find_by_name(fstypename);
292 mp = kmalloc(sizeof(struct mount), M_MOUNT, M_WAITOK | M_ZERO);
293 lockinit(&mp->mnt_lock, "vfslock", VLKTIMEOUT, 0);
294 vfs_busy(mp, LK_NOWAIT);
295 TAILQ_INIT(&mp->mnt_nvnodelist);
296 TAILQ_INIT(&mp->mnt_reservedvnlist);
297 TAILQ_INIT(&mp->mnt_jlist);
298 mp->mnt_nvnodelistsize = 0;
300 mp->mnt_op = vfsp->vfc_vfsops;
301 mp->mnt_flag = MNT_RDONLY;
302 vfsp->vfc_refcount++;
303 mp->mnt_iosize_max = DFLTPHYS;
304 mp->mnt_stat.f_type = vfsp->vfc_typenum;
305 mp->mnt_flag |= vfsp->vfc_flags & MNT_VISFLAGMASK;
306 strncpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN);
307 copystr(devname, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 0);
313 * Lookup a mount point by filesystem identifier.
316 vfs_getvfs(fsid_t *fsid)
321 lwkt_gettoken(&ilock, &mountlist_token);
322 TAILQ_FOREACH(mp, &mountlist, mnt_list) {
323 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
324 mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
328 lwkt_reltoken(&ilock);
333 * Get a new unique fsid. Try to make its val[0] unique, since this value
334 * will be used to create fake device numbers for stat(). Also try (but
335 * not so hard) make its val[0] unique mod 2^16, since some emulators only
336 * support 16-bit device numbers. We end up with unique val[0]'s for the
337 * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls.
339 * Keep in mind that several mounts may be running in parallel. Starting
340 * the search one past where the previous search terminated is both a
341 * micro-optimization and a defense against returning the same fsid to
345 vfs_getnewfsid(struct mount *mp)
347 static u_int16_t mntid_base;
352 lwkt_gettoken(&ilock, &mntid_token);
353 mtype = mp->mnt_vfc->vfc_typenum;
354 tfsid.val[1] = mtype;
355 mtype = (mtype & 0xFF) << 24;
357 tfsid.val[0] = makeudev(255,
358 mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF));
360 if (vfs_getvfs(&tfsid) == NULL)
363 mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
364 mp->mnt_stat.f_fsid.val[1] = tfsid.val[1];
365 lwkt_reltoken(&ilock);
369 * Set the FSID for a new mount point to the template. Adjust
370 * the FSID to avoid collisions.
373 vfs_setfsid(struct mount *mp, fsid_t *template)
377 bzero(&mp->mnt_stat.f_fsid, sizeof(mp->mnt_stat.f_fsid));
379 if (vfs_getvfs(template) == NULL)
384 mp->mnt_stat.f_fsid = *template;
389 * This routine is called when we have too many vnodes. It attempts
390 * to free <count> vnodes and will potentially free vnodes that still
391 * have VM backing store (VM backing store is typically the cause
392 * of a vnode blowout so we want to do this). Therefore, this operation
393 * is not considered cheap.
395 * A number of conditions may prevent a vnode from being reclaimed.
396 * the buffer cache may have references on the vnode, a directory
397 * vnode may still have references due to the namei cache representing
398 * underlying files, or the vnode may be in active use. It is not
399 * desireable to reuse such vnodes. These conditions may cause the
400 * number of vnodes to reach some minimum value regardless of what
401 * you set kern.maxvnodes to. Do not set kern.maxvnodes too low.
405 * This is a quick non-blocking check to determine if the vnode is a good
406 * candidate for being (eventually) vgone()'d. Returns 0 if the vnode is
407 * not a good candidate, 1 if it is.
410 vmightfree(struct vnode *vp, int page_count, int pass)
412 if (vp->v_flag & VRECLAIMED)
415 if ((vp->v_flag & VFREE) && TAILQ_EMPTY(&vp->v_namecache))
418 if (sysref_isactive(&vp->v_sysref))
420 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
424 * XXX horrible hack. Up to four passes will be taken. Each pass
425 * makes a larger set of vnodes eligible. For now what this really
426 * means is that we try to recycle files opened only once before
427 * recycling files opened multiple times.
429 switch(vp->v_flag & (VAGE0 | VAGE1)) {
449 * The vnode was found to be possibly vgone()able and the caller has locked it
450 * (thus the usecount should be 1 now). Determine if the vnode is actually
451 * vgone()able, doing some cleanups in the process. Returns 1 if the vnode
452 * can be vgone()'d, 0 otherwise.
454 * Note that v_auxrefs may be non-zero because (A) this vnode is not a leaf
455 * in the namecache topology and (B) this vnode has buffer cache bufs.
456 * We cannot remove vnodes with non-leaf namecache associations. We do a
457 * tentitive leaf check prior to attempting to flush out any buffers but the
458 * 'real' test when all is said in done is that v_auxrefs must become 0 for
459 * the vnode to be freeable.
461 * We could theoretically just unconditionally flush when v_auxrefs != 0,
462 * but flushing data associated with non-leaf nodes (which are always
463 * directories), just throws it away for no benefit. It is the buffer
464 * cache's responsibility to choose buffers to recycle from the cached
465 * data point of view.
468 visleaf(struct vnode *vp)
470 struct namecache *ncp;
472 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
473 if (!TAILQ_EMPTY(&ncp->nc_list))
480 * Try to clean up the vnode to the point where it can be vgone()'d, returning
481 * 0 if it cannot be vgone()'d (or already has been), 1 if it can. Unlike
482 * vmightfree() this routine may flush the vnode and block. Vnodes marked
483 * VFREE are still candidates for vgone()ing because they may hold namecache
484 * resources and could be blocking the namecache directory hierarchy (and
485 * related vnodes) from being freed.
488 vtrytomakegoneable(struct vnode *vp, int page_count)
490 if (vp->v_flag & VRECLAIMED)
492 if (vp->v_sysref.refcnt > 1)
494 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
496 if (vp->v_auxrefs && visleaf(vp)) {
497 vinvalbuf(vp, V_SAVE, 0, 0);
499 kprintf((vp->v_auxrefs ? "vrecycle: vp %p failed: %s\n" :
500 "vrecycle: vp %p succeeded: %s\n"), vp,
501 (TAILQ_FIRST(&vp->v_namecache) ?
502 TAILQ_FIRST(&vp->v_namecache)->nc_name : "?"));
507 * This sequence may seem a little strange, but we need to optimize
508 * the critical path a bit. We can't recycle vnodes with other
509 * references and because we are trying to recycle an otherwise
510 * perfectly fine vnode we have to invalidate the namecache in a
511 * way that avoids possible deadlocks (since the vnode lock is being
512 * held here). Finally, we have to check for other references one
513 * last time in case something snuck in during the inval.
515 if (vp->v_sysref.refcnt > 1 || vp->v_auxrefs != 0)
517 if (cache_inval_vp_nonblock(vp))
519 return (vp->v_sysref.refcnt <= 1 && vp->v_auxrefs == 0);
523 * Reclaim up to 1/10 of the vnodes associated with a mount point. Try
524 * to avoid vnodes which have lots of resident pages (we are trying to free
525 * vnodes, not memory).
527 * This routine is a callback from the mountlist scan. The mount point
528 * in question will be busied.
530 * NOTE: The 1/10 reclamation also ensures that the inactive data set
531 * (the vnodes being recycled by the one-time use) does not degenerate
532 * into too-small a set. This is important because once a vnode is
533 * marked as not being one-time-use (VAGE0/VAGE1 both 0) that vnode
534 * will not be destroyed EXCEPT by this mechanism. VM pages can still
535 * be cleaned/freed by the pageout daemon.
538 vlrureclaim(struct mount *mp, void *data)
540 struct vnlru_info *info = data;
547 int trigger_mult = vnlru_nowhere;
550 * Calculate the trigger point for the resident pages check. The
551 * minimum trigger value is approximately the number of pages in
552 * the system divded by the number of vnodes. However, due to
553 * various other system memory overheads unrelated to data caching
554 * it is a good idea to double the trigger (at least).
556 * trigger_mult starts at 0. If the recycler is having problems
557 * finding enough freeable vnodes it will increase trigger_mult.
558 * This should not happen in normal operation, even on machines with
559 * low amounts of memory, but extraordinary memory use by the system
560 * verses the amount of cached data can trigger it.
562 usevnodes = desiredvnodes;
565 trigger = vmstats.v_page_count * (trigger_mult + 2) / usevnodes;
568 lwkt_gettoken(&ilock, &mntvnode_token);
569 count = mp->mnt_nvnodelistsize / 10 + 1;
571 while (count && mp->mnt_syncer) {
573 * Next vnode. Use the special syncer vnode to placemark
574 * the LRU. This way the LRU code does not interfere with
577 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes);
578 TAILQ_REMOVE(&mp->mnt_nvnodelist, mp->mnt_syncer, v_nmntvnodes);
580 TAILQ_INSERT_AFTER(&mp->mnt_nvnodelist, vp,
581 mp->mnt_syncer, v_nmntvnodes);
583 TAILQ_INSERT_HEAD(&mp->mnt_nvnodelist, mp->mnt_syncer,
585 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes);
593 * The VP will stick around while we hold mntvnode_token,
594 * at least until we block, so we can safely do an initial
595 * check, and then must check again after we lock the vnode.
597 if (vp->v_type == VNON || /* syncer or indeterminant */
598 !vmightfree(vp, trigger, info->pass) /* critical path opt */
605 * VX get the candidate vnode. If the VX get fails the
606 * vnode might still be on the mountlist. Our loop depends
607 * on us at least cycling the vnode to the end of the
610 if (vx_get_nonblock(vp) != 0) {
616 * Since we blocked locking the vp, make sure it is still
617 * a candidate for reclamation. That is, it has not already
618 * been reclaimed and only has our VX reference associated
621 if (vp->v_type == VNON || /* syncer or indeterminant */
622 (vp->v_flag & VRECLAIMED) ||
624 !vtrytomakegoneable(vp, trigger) /* critical path opt */
632 * All right, we are good, move the vp to the end of the
633 * mountlist and clean it out. The vget will have returned
634 * an error if the vnode was destroyed (VRECLAIMED set), so we
635 * do not have to check again. The vput() will move the
636 * vnode to the free list if the vgone() was successful.
638 KKASSERT(vp->v_mount == mp);
644 lwkt_reltoken(&ilock);
649 * Attempt to recycle vnodes in a context that is always safe to block.
650 * Calling vlrurecycle() from the bowels of file system code has some
651 * interesting deadlock problems.
653 static struct thread *vnlruthread;
654 static int vnlruproc_sig;
657 vnlru_proc_wait(void)
659 if (vnlruproc_sig == 0) {
660 vnlruproc_sig = 1; /* avoid unnecessary wakeups */
663 tsleep(&vnlruproc_sig, 0, "vlruwk", hz);
669 struct thread *td = curthread;
670 struct vnlru_info info;
673 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td,
678 kproc_suspend_loop();
681 * Try to free some vnodes if we have too many
683 if (numvnodes > desiredvnodes &&
684 freevnodes > desiredvnodes * 2 / 10) {
685 int count = numvnodes - desiredvnodes;
687 if (count > freevnodes / 100)
688 count = freevnodes / 100;
691 freesomevnodes(count);
695 * Nothing to do if most of our vnodes are already on
698 if (numvnodes - freevnodes <= desiredvnodes * 9 / 10) {
700 wakeup(&vnlruproc_sig);
701 tsleep(td, 0, "vlruwt", hz);
707 * The pass iterates through the four combinations of
708 * VAGE0/VAGE1. We want to get rid of aged small files
713 while (done == 0 && info.pass < 4) {
714 done = mountlist_scan(vlrureclaim, &info,
720 * The vlrureclaim() call only processes 1/10 of the vnodes
721 * on each mount. If we couldn't find any repeat the loop
722 * at least enough times to cover all available vnodes before
723 * we start sleeping. Complain if the failure extends past
724 * 30 second, every 30 seconds.
728 if (vnlru_nowhere % 10 == 0)
729 tsleep(td, 0, "vlrup", hz * 3);
730 if (vnlru_nowhere % 100 == 0)
731 kprintf("vnlru_proc: vnode recycler stopped working!\n");
732 if (vnlru_nowhere == 1000)
742 * MOUNTLIST FUNCTIONS
746 * mountlist_insert (MP SAFE)
748 * Add a new mount point to the mount list.
751 mountlist_insert(struct mount *mp, int how)
755 lwkt_gettoken(&ilock, &mountlist_token);
756 if (how == MNTINS_FIRST)
757 TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
759 TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
760 lwkt_reltoken(&ilock);
764 * mountlist_interlock (MP SAFE)
766 * Execute the specified interlock function with the mountlist token
767 * held. The function will be called in a serialized fashion verses
768 * other functions called through this mechanism.
771 mountlist_interlock(int (*callback)(struct mount *), struct mount *mp)
776 lwkt_gettoken(&ilock, &mountlist_token);
777 error = callback(mp);
778 lwkt_reltoken(&ilock);
783 * mountlist_boot_getfirst (DURING BOOT ONLY)
785 * This function returns the first mount on the mountlist, which is
786 * expected to be the root mount. Since no interlocks are obtained
787 * this function is only safe to use during booting.
791 mountlist_boot_getfirst(void)
793 return(TAILQ_FIRST(&mountlist));
797 * mountlist_remove (MP SAFE)
799 * Remove a node from the mountlist. If this node is the next scan node
800 * for any active mountlist scans, the active mountlist scan will be
801 * adjusted to skip the node, thus allowing removals during mountlist
805 mountlist_remove(struct mount *mp)
807 struct mountscan_info *msi;
810 lwkt_gettoken(&ilock, &mountlist_token);
811 TAILQ_FOREACH(msi, &mountscan_list, msi_entry) {
812 if (msi->msi_node == mp) {
813 if (msi->msi_how & MNTSCAN_FORWARD)
814 msi->msi_node = TAILQ_NEXT(mp, mnt_list);
816 msi->msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
819 TAILQ_REMOVE(&mountlist, mp, mnt_list);
820 lwkt_reltoken(&ilock);
824 * mountlist_scan (MP SAFE)
826 * Safely scan the mount points on the mount list. Unless otherwise
827 * specified each mount point will be busied prior to the callback and
828 * unbusied afterwords. The callback may safely remove any mount point
829 * without interfering with the scan. If the current callback
830 * mount is removed the scanner will not attempt to unbusy it.
832 * If a mount node cannot be busied it is silently skipped.
834 * The callback return value is aggregated and a total is returned. A return
835 * value of < 0 is not aggregated and will terminate the scan.
837 * MNTSCAN_FORWARD - the mountlist is scanned in the forward direction
838 * MNTSCAN_REVERSE - the mountlist is scanned in reverse
839 * MNTSCAN_NOBUSY - the scanner will make the callback without busying
843 mountlist_scan(int (*callback)(struct mount *, void *), void *data, int how)
845 struct mountscan_info info;
852 lwkt_gettoken(&ilock, &mountlist_token);
855 info.msi_node = NULL; /* paranoia */
856 TAILQ_INSERT_TAIL(&mountscan_list, &info, msi_entry);
861 if (how & MNTSCAN_FORWARD) {
862 info.msi_node = TAILQ_FIRST(&mountlist);
863 while ((mp = info.msi_node) != NULL) {
864 if (how & MNTSCAN_NOBUSY) {
865 count = callback(mp, data);
866 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
867 count = callback(mp, data);
868 if (mp == info.msi_node)
876 if (mp == info.msi_node)
877 info.msi_node = TAILQ_NEXT(mp, mnt_list);
879 } else if (how & MNTSCAN_REVERSE) {
880 info.msi_node = TAILQ_LAST(&mountlist, mntlist);
881 while ((mp = info.msi_node) != NULL) {
882 if (how & MNTSCAN_NOBUSY) {
883 count = callback(mp, data);
884 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
885 count = callback(mp, data);
886 if (mp == info.msi_node)
894 if (mp == info.msi_node)
895 info.msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
898 TAILQ_REMOVE(&mountscan_list, &info, msi_entry);
899 lwkt_reltoken(&ilock);
904 * MOUNT RELATED VNODE FUNCTIONS
907 static struct kproc_desc vnlru_kp = {
912 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp)
915 * Move a vnode from one mount queue to another.
918 insmntque(struct vnode *vp, struct mount *mp)
922 lwkt_gettoken(&ilock, &mntvnode_token);
924 * Delete from old mount point vnode list, if on one.
926 if (vp->v_mount != NULL) {
927 KASSERT(vp->v_mount->mnt_nvnodelistsize > 0,
928 ("bad mount point vnode list size"));
930 vp->v_mount->mnt_nvnodelistsize--;
933 * Insert into list of vnodes for the new mount point, if available.
934 * The 'end' of the LRU list is the vnode prior to mp->mnt_syncer.
936 if ((vp->v_mount = mp) == NULL) {
937 lwkt_reltoken(&ilock);
940 if (mp->mnt_syncer) {
941 TAILQ_INSERT_BEFORE(mp->mnt_syncer, vp, v_nmntvnodes);
943 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
945 mp->mnt_nvnodelistsize++;
946 lwkt_reltoken(&ilock);
951 * Scan the vnodes under a mount point and issue appropriate callbacks.
953 * The fastfunc() callback is called with just the mountlist token held
954 * (no vnode lock). It may not block and the vnode may be undergoing
955 * modifications while the caller is processing it. The vnode will
956 * not be entirely destroyed, however, due to the fact that the mountlist
957 * token is held. A return value < 0 skips to the next vnode without calling
958 * the slowfunc(), a return value > 0 terminates the loop.
960 * The slowfunc() callback is called after the vnode has been successfully
961 * locked based on passed flags. The vnode is skipped if it gets rearranged
962 * or destroyed while blocking on the lock. A non-zero return value from
963 * the slow function terminates the loop. The slow function is allowed to
964 * arbitrarily block. The scanning code guarentees consistency of operation
965 * even if the slow function deletes or moves the node, or blocks and some
966 * other thread deletes or moves the node.
972 int (*fastfunc)(struct mount *mp, struct vnode *vp, void *data),
973 int (*slowfunc)(struct mount *mp, struct vnode *vp, void *data),
976 struct vmntvnodescan_info info;
980 int maxcount = 1000000;
984 lwkt_gettoken(&ilock, &mntvnode_token);
987 * If asked to do one pass stop after iterating available vnodes.
988 * Under heavy loads new vnodes can be added while we are scanning,
989 * so this isn't perfect. Create a slop factor of 2x.
991 if (flags & VMSC_ONEPASS)
992 stopcount = mp->mnt_nvnodelistsize * 2;
994 info.vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
995 TAILQ_INSERT_TAIL(&mntvnodescan_list, &info, entry);
996 while ((vp = info.vp) != NULL) {
998 panic("maxcount reached during vmntvnodescan");
1001 * Skip if visible but not ready, or special (e.g.
1004 if (vp->v_type == VNON)
1006 KKASSERT(vp->v_mount == mp);
1009 * Quick test. A negative return continues the loop without
1010 * calling the slow test. 0 continues onto the slow test.
1011 * A positive number aborts the loop.
1014 if ((r = fastfunc(mp, vp, data)) < 0) {
1023 * Get a vxlock on the vnode, retry if it has moved or isn't
1024 * in the mountlist where we expect it.
1029 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) {
1031 error = vget(vp, LK_EXCLUSIVE);
1033 case VMSC_GETVP|VMSC_NOWAIT:
1034 error = vget(vp, LK_EXCLUSIVE|LK_NOWAIT);
1047 * Do not call the slow function if the vnode is
1048 * invalid or if it was ripped out from under us
1049 * while we (potentially) blocked.
1051 if (info.vp == vp && vp->v_type != VNON)
1052 r = slowfunc(mp, vp, data);
1057 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) {
1059 case VMSC_GETVP|VMSC_NOWAIT:
1074 * Yield after some processing. Depending on the number
1075 * of vnodes, we might wind up running for a long time.
1076 * Because threads are not preemptable, time critical
1077 * userland processes might starve. Give them a chance
1080 if (++count == 10000) {
1081 /* We really want to yield a bit, so we simply sleep a tick */
1082 tsleep(mp, 0, "vnodescn", 1);
1087 * If doing one pass this decrements to zero. If it starts
1088 * at zero it is effectively unlimited for the purposes of
1091 if (--stopcount == 0)
1095 * Iterate. If the vnode was ripped out from under us
1096 * info.vp will already point to the next vnode, otherwise
1097 * we have to obtain the next valid vnode ourselves.
1100 info.vp = TAILQ_NEXT(vp, v_nmntvnodes);
1102 TAILQ_REMOVE(&mntvnodescan_list, &info, entry);
1103 lwkt_reltoken(&ilock);
1108 * Remove any vnodes in the vnode table belonging to mount point mp.
1110 * If FORCECLOSE is not specified, there should not be any active ones,
1111 * return error if any are found (nb: this is a user error, not a
1112 * system error). If FORCECLOSE is specified, detach any active vnodes
1115 * If WRITECLOSE is set, only flush out regular file vnodes open for
1118 * SKIPSYSTEM causes any vnodes marked VSYSTEM to be skipped.
1120 * `rootrefs' specifies the base reference count for the root vnode
1121 * of this filesystem. The root vnode is considered busy if its
1122 * v_sysref.refcnt exceeds this value. On a successful return, vflush()
1123 * will call vrele() on the root vnode exactly rootrefs times.
1124 * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must
1128 static int busyprt = 0; /* print out busy vnodes */
1129 SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, "");
1132 static int vflush_scan(struct mount *mp, struct vnode *vp, void *data);
1134 struct vflush_info {
1141 vflush(struct mount *mp, int rootrefs, int flags)
1143 struct thread *td = curthread; /* XXX */
1144 struct vnode *rootvp = NULL;
1146 struct vflush_info vflush_info;
1149 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0,
1150 ("vflush: bad args"));
1152 * Get the filesystem root vnode. We can vput() it
1153 * immediately, since with rootrefs > 0, it won't go away.
1155 if ((error = VFS_ROOT(mp, &rootvp)) != 0) {
1156 if ((flags & FORCECLOSE) == 0)
1159 /* continue anyway */
1165 vflush_info.busy = 0;
1166 vflush_info.flags = flags;
1167 vflush_info.td = td;
1168 vmntvnodescan(mp, VMSC_GETVX, NULL, vflush_scan, &vflush_info);
1170 if (rootrefs > 0 && (flags & FORCECLOSE) == 0) {
1172 * If just the root vnode is busy, and if its refcount
1173 * is equal to `rootrefs', then go ahead and kill it.
1175 KASSERT(vflush_info.busy > 0, ("vflush: not busy"));
1176 KASSERT(rootvp->v_sysref.refcnt >= rootrefs, ("vflush: rootrefs"));
1177 if (vflush_info.busy == 1 && rootvp->v_sysref.refcnt == rootrefs) {
1179 vgone_vxlocked(rootvp);
1181 vflush_info.busy = 0;
1184 if (vflush_info.busy)
1186 for (; rootrefs > 0; rootrefs--)
1192 * The scan callback is made with an VX locked vnode.
1195 vflush_scan(struct mount *mp, struct vnode *vp, void *data)
1197 struct vflush_info *info = data;
1201 * Skip over a vnodes marked VSYSTEM.
1203 if ((info->flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM)) {
1208 * If WRITECLOSE is set, flush out unlinked but still open
1209 * files (even if open only for reading) and regular file
1210 * vnodes open for writing.
1212 if ((info->flags & WRITECLOSE) &&
1213 (vp->v_type == VNON ||
1214 (VOP_GETATTR(vp, &vattr) == 0 &&
1215 vattr.va_nlink > 0)) &&
1216 (vp->v_writecount == 0 || vp->v_type != VREG)) {
1221 * If we are the only holder (refcnt of 1) or the vnode is in
1222 * termination (refcnt < 0), we can vgone the vnode.
1224 if (vp->v_sysref.refcnt <= 1) {
1230 * If FORCECLOSE is set, forcibly close the vnode. For block
1231 * or character devices we just clean and leave the vp
1232 * associated with devfs. For all other files, just kill them.
1234 * XXX we need to do something about devfs here, I'd rather not
1235 * blow away device associations.
1237 if (info->flags & FORCECLOSE) {
1240 if (vp->v_type != VBLK && vp->v_type != VCHR) {
1243 vclean_vxlocked(vp, 0);
1244 /*vp->v_ops = &devfs_vnode_dev_vops_p;*/
1245 insmntque(vp, NULL);
1252 vprint("vflush: busy vnode", vp);
1259 add_bio_ops(struct bio_ops *ops)
1261 TAILQ_INSERT_TAIL(&bio_ops_list, ops, entry);
1265 rem_bio_ops(struct bio_ops *ops)
1267 TAILQ_REMOVE(&bio_ops_list, ops, entry);
1271 * This calls the bio_ops io_sync function either for a mount point
1274 * WARNING: softdeps is weirdly coded and just isn't happy unless
1275 * io_sync is called with a NULL mount from the general syncing code.
1278 bio_ops_sync(struct mount *mp)
1280 struct bio_ops *ops;
1283 if ((ops = mp->mnt_bioops) != NULL)
1286 TAILQ_FOREACH(ops, &bio_ops_list, entry) {