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.
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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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60 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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64 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 1.23 2006/09/19 16:06:11 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>
96 #include <vm/vm_object.h>
98 struct mountscan_info {
99 TAILQ_ENTRY(mountscan_info) msi_entry;
101 struct mount *msi_node;
104 struct vmntvnodescan_info {
105 TAILQ_ENTRY(vmntvnodescan_info) entry;
109 static int vnlru_nowhere = 0;
110 SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RD,
112 "Number of times the vnlru process ran without success");
115 static struct lwkt_token mntid_token;
117 static struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist);
118 static TAILQ_HEAD(,mountscan_info) mountscan_list;
119 static struct lwkt_token mountlist_token;
120 static TAILQ_HEAD(,vmntvnodescan_info) mntvnodescan_list;
121 struct lwkt_token mntvnode_token;
124 * Called from vfsinit()
129 lwkt_token_init(&mountlist_token);
130 lwkt_token_init(&mntvnode_token);
131 lwkt_token_init(&mntid_token);
132 TAILQ_INIT(&mountscan_list);
133 TAILQ_INIT(&mntvnodescan_list);
137 * Support function called with mntvnode_token held to remove a vnode
138 * from the mountlist. We must update any list scans which are in progress.
141 vremovevnodemnt(struct vnode *vp)
143 struct vmntvnodescan_info *info;
145 TAILQ_FOREACH(info, &mntvnodescan_list, entry) {
147 info->vp = TAILQ_NEXT(vp, v_nmntvnodes);
149 TAILQ_REMOVE(&vp->v_mount->mnt_nvnodelist, vp, v_nmntvnodes);
153 * Support function called with mntvnode_token held to move a vnode to
154 * the end of the list.
157 vmovevnodetoend(struct mount *mp, struct vnode *vp)
160 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
165 * Allocate a new vnode and associate it with a tag, mount point, and
168 * A VX locked and refd vnode is returned. The caller should setup the
169 * remaining fields and vx_put() or, if he wishes to leave a vref,
170 * vx_unlock() the vnode.
173 getnewvnode(enum vtagtype tag, struct mount *mp,
174 struct vnode **vpp, int lktimeout, int lkflags)
178 KKASSERT(mp != NULL);
180 vp = allocvnode(lktimeout, lkflags);
185 * By default the vnode is assigned the mount point's normal
188 vp->v_ops = &mp->mnt_vn_use_ops;
191 * Placing the vnode on the mount point's queue makes it visible.
192 * VNON prevents it from being messed with, however.
197 * A VX locked & refd vnode is returned.
204 * This function creates vnodes with special operations vectors. The
205 * mount point is optional.
207 * This routine is being phased out.
210 getspecialvnode(enum vtagtype tag, struct mount *mp,
211 struct vop_ops **ops,
212 struct vnode **vpp, int lktimeout, int lkflags)
216 vp = allocvnode(lktimeout, lkflags);
222 * Placing the vnode on the mount point's queue makes it visible.
223 * VNON prevents it from being messed with, however.
228 * A VX locked & refd vnode is returned.
235 * Interlock against an unmount, return 0 on success, non-zero on failure.
237 * The passed flag may be 0 or LK_NOWAIT and is only used if an unmount
240 * If no unmount is in-progress LK_NOWAIT is ignored. No other flag bits
241 * are used. A shared locked will be obtained and the filesystem will not
242 * be unmountable until the lock is released.
245 vfs_busy(struct mount *mp, int flags)
249 if (mp->mnt_kern_flag & MNTK_UNMOUNT) {
250 if (flags & LK_NOWAIT)
252 /* XXX not MP safe */
253 mp->mnt_kern_flag |= MNTK_MWAIT;
255 * Since all busy locks are shared except the exclusive
256 * lock granted when unmounting, the only place that a
257 * wakeup needs to be done is at the release of the
258 * exclusive lock at the end of dounmount.
260 tsleep((caddr_t)mp, 0, "vfs_busy", 0);
264 if (lockmgr(&mp->mnt_lock, lkflags))
265 panic("vfs_busy: unexpected lock failure");
270 * Free a busy filesystem.
273 vfs_unbusy(struct mount *mp)
275 lockmgr(&mp->mnt_lock, LK_RELEASE);
279 * Lookup a filesystem type, and if found allocate and initialize
280 * a mount structure for it.
282 * Devname is usually updated by mount(8) after booting.
285 vfs_rootmountalloc(char *fstypename, char *devname, struct mount **mpp)
287 struct vfsconf *vfsp;
290 if (fstypename == NULL)
292 for (vfsp = vfsconf; vfsp; vfsp = vfsp->vfc_next) {
293 if (!strcmp(vfsp->vfc_name, fstypename))
298 mp = kmalloc(sizeof(struct mount), M_MOUNT, M_WAITOK);
299 bzero((char *)mp, (u_long)sizeof(struct mount));
300 lockinit(&mp->mnt_lock, "vfslock", VLKTIMEOUT, 0);
301 vfs_busy(mp, LK_NOWAIT);
302 TAILQ_INIT(&mp->mnt_nvnodelist);
303 TAILQ_INIT(&mp->mnt_reservedvnlist);
304 TAILQ_INIT(&mp->mnt_jlist);
305 mp->mnt_nvnodelistsize = 0;
307 mp->mnt_op = vfsp->vfc_vfsops;
308 mp->mnt_flag = MNT_RDONLY;
309 vfsp->vfc_refcount++;
310 mp->mnt_iosize_max = DFLTPHYS;
311 mp->mnt_stat.f_type = vfsp->vfc_typenum;
312 mp->mnt_flag |= vfsp->vfc_flags & MNT_VISFLAGMASK;
313 strncpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN);
314 copystr(devname, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 0);
320 * Lookup a mount point by filesystem identifier.
323 vfs_getvfs(fsid_t *fsid)
328 lwkt_gettoken(&ilock, &mountlist_token);
329 TAILQ_FOREACH(mp, &mountlist, mnt_list) {
330 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
331 mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
335 lwkt_reltoken(&ilock);
340 * Get a new unique fsid. Try to make its val[0] unique, since this value
341 * will be used to create fake device numbers for stat(). Also try (but
342 * not so hard) make its val[0] unique mod 2^16, since some emulators only
343 * support 16-bit device numbers. We end up with unique val[0]'s for the
344 * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls.
346 * Keep in mind that several mounts may be running in parallel. Starting
347 * the search one past where the previous search terminated is both a
348 * micro-optimization and a defense against returning the same fsid to
352 vfs_getnewfsid(struct mount *mp)
354 static u_int16_t mntid_base;
359 lwkt_gettoken(&ilock, &mntid_token);
360 mtype = mp->mnt_vfc->vfc_typenum;
361 tfsid.val[1] = mtype;
362 mtype = (mtype & 0xFF) << 24;
364 tfsid.val[0] = makeudev(255,
365 mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF));
367 if (vfs_getvfs(&tfsid) == NULL)
370 mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
371 mp->mnt_stat.f_fsid.val[1] = tfsid.val[1];
372 lwkt_reltoken(&ilock);
376 * This routine is called when we have too many vnodes. It attempts
377 * to free <count> vnodes and will potentially free vnodes that still
378 * have VM backing store (VM backing store is typically the cause
379 * of a vnode blowout so we want to do this). Therefore, this operation
380 * is not considered cheap.
382 * A number of conditions may prevent a vnode from being reclaimed.
383 * the buffer cache may have references on the vnode, a directory
384 * vnode may still have references due to the namei cache representing
385 * underlying files, or the vnode may be in active use. It is not
386 * desireable to reuse such vnodes. These conditions may cause the
387 * number of vnodes to reach some minimum value regardless of what
388 * you set kern.maxvnodes to. Do not set kern.maxvnodes too low.
392 * This is a quick non-blocking check to determine if the vnode is a good
393 * candidate for being (eventually) vgone()'d. Returns 0 if the vnode is
394 * not a good candidate, 1 if it is.
396 * Note that a vnode can be marked VFREE without really being free, so
397 * we don't use the flag for any tests.
400 vmightfree(struct vnode *vp, int page_count)
402 if (vp->v_flag & VRECLAIMED)
405 if ((vp->v_flag & VFREE) && TAILQ_EMPTY(&vp->v_namecache))
408 if (vp->v_usecount != 0)
410 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
416 * The vnode was found to be possibly vgone()able and the caller has locked it
417 * (thus the usecount should be 1 now). Determine if the vnode is actually
418 * vgone()able, doing some cleanups in the process. Returns 1 if the vnode
419 * can be vgone()'d, 0 otherwise.
421 * Note that v_holdcnt may be non-zero because (A) this vnode is not a leaf
422 * in the namecache topology and (B) this vnode has buffer cache bufs.
423 * We cannot remove vnodes with non-leaf namecache associations. We do a
424 * tentitive leaf check prior to attempting to flush out any buffers but the
425 * 'real' test when all is said in done is that v_holdcnt must become 0 for
426 * the vnode to be freeable.
428 * We could theoretically just unconditionally flush when v_holdcnt != 0,
429 * but flushing data associated with non-leaf nodes (which are always
430 * directories), just throws it away for no benefit. It is the buffer
431 * cache's responsibility to choose buffers to recycle from the cached
432 * data point of view.
435 visleaf(struct vnode *vp)
437 struct namecache *ncp;
439 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
440 if (!TAILQ_EMPTY(&ncp->nc_list))
447 * Try to clean up the vnode to the point where it can be vgone()'d, returning
448 * 0 if it cannot be vgone()'d (or already has been), 1 if it can. Unlike
449 * vmightfree() this routine may flush the vnode and block. Vnodes marked
450 * VFREE are still candidates for vgone()ing because they may hold namecache
451 * resources and could be blocking the namecache directory hierarchy (and
452 * related vnodes) from being freed.
455 vtrytomakegoneable(struct vnode *vp, int page_count)
457 if (vp->v_flag & VRECLAIMED)
459 if (vp->v_usecount != 1)
461 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
463 if (vp->v_holdcnt && visleaf(vp)) {
464 vinvalbuf(vp, V_SAVE, 0, 0);
466 printf((vp->v_holdcnt ? "vrecycle: vp %p failed: %s\n" :
467 "vrecycle: vp %p succeeded: %s\n"), vp,
468 (TAILQ_FIRST(&vp->v_namecache) ?
469 TAILQ_FIRST(&vp->v_namecache)->nc_name : "?"));
472 return(vp->v_usecount == 1 && vp->v_holdcnt == 0);
476 * Reclaim up to 1/10 of the vnodes associated with a mount point. Try
477 * to avoid vnodes which have lots of resident pages (we are trying to free
478 * vnodes, not memory).
480 * This routine is a callback from the mountlist scan. The mount point
481 * in question will be busied.
484 vlrureclaim(struct mount *mp, void *data)
492 int trigger_mult = vnlru_nowhere;
495 * Calculate the trigger point for the resident pages check. The
496 * minimum trigger value is approximately the number of pages in
497 * the system divded by the number of vnodes. However, due to
498 * various other system memory overheads unrelated to data caching
499 * it is a good idea to double the trigger (at least).
501 * trigger_mult starts at 0. If the recycler is having problems
502 * finding enough freeable vnodes it will increase trigger_mult.
503 * This should not happen in normal operation, even on machines with
504 * low amounts of memory, but extraordinary memory use by the system
505 * verses the amount of cached data can trigger it.
507 usevnodes = desiredvnodes;
510 trigger = vmstats.v_page_count * (trigger_mult + 2) / usevnodes;
513 lwkt_gettoken(&ilock, &mntvnode_token);
514 count = mp->mnt_nvnodelistsize / 10 + 1;
515 while (count && (vp = TAILQ_FIRST(&mp->mnt_nvnodelist)) != NULL) {
519 * The VP will stick around while we hold mntvnode_token,
520 * at least until we block, so we can safely do an initial
521 * check, and then must check again after we lock the vnode.
523 if (vp->v_type == VNON || /* XXX */
524 vp->v_type == VBAD || /* XXX */
525 !vmightfree(vp, trigger) /* critical path opt */
527 vmovevnodetoend(mp, vp);
533 * VX get the candidate vnode. If the VX get fails the
534 * vnode might still be on the mountlist. Our loop depends
535 * on us at least cycling the vnode to the end of the
538 if (vx_get_nonblock(vp) != 0) {
539 if (vp->v_mount == mp)
540 vmovevnodetoend(mp, vp);
546 * Since we blocked locking the vp, make sure it is still
547 * a candidate for reclamation. That is, it has not already
548 * been reclaimed and only has our VX reference associated
551 if (vp->v_type == VNON || /* XXX */
552 vp->v_type == VBAD || /* XXX */
553 (vp->v_flag & VRECLAIMED) ||
555 !vtrytomakegoneable(vp, trigger) /* critical path opt */
557 if (vp->v_mount == mp)
558 vmovevnodetoend(mp, vp);
565 * All right, we are good, move the vp to the end of the
566 * mountlist and clean it out. The vget will have returned
567 * an error if the vnode was destroyed (VRECLAIMED set), so we
568 * do not have to check again. The vput() will move the
569 * vnode to the free list if the vgone() was successful.
571 KKASSERT(vp->v_mount == mp);
572 vmovevnodetoend(mp, vp);
578 lwkt_reltoken(&ilock);
583 * Attempt to recycle vnodes in a context that is always safe to block.
584 * Calling vlrurecycle() from the bowels of file system code has some
585 * interesting deadlock problems.
587 static struct thread *vnlruthread;
588 static int vnlruproc_sig;
591 vnlru_proc_wait(void)
593 if (vnlruproc_sig == 0) {
594 vnlruproc_sig = 1; /* avoid unnecessary wakeups */
597 tsleep(&vnlruproc_sig, 0, "vlruwk", hz);
603 struct thread *td = curthread;
606 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td,
611 kproc_suspend_loop();
612 if (numvnodes - freevnodes <= desiredvnodes * 9 / 10) {
614 wakeup(&vnlruproc_sig);
615 tsleep(td, 0, "vlruwt", hz);
619 done = mountlist_scan(vlrureclaim, NULL, MNTSCAN_FORWARD);
622 * The vlrureclaim() call only processes 1/10 of the vnodes
623 * on each mount. If we couldn't find any repeat the loop
624 * at least enough times to cover all available vnodes before
625 * we start sleeping. Complain if the failure extends past
626 * 30 second, every 30 seconds.
630 if (vnlru_nowhere % 10 == 0)
631 tsleep(td, 0, "vlrup", hz * 3);
632 if (vnlru_nowhere % 100 == 0)
633 printf("vnlru_proc: vnode recycler stopped working!\n");
634 if (vnlru_nowhere == 1000)
644 * MOUNTLIST FUNCTIONS
648 * mountlist_insert (MP SAFE)
650 * Add a new mount point to the mount list.
653 mountlist_insert(struct mount *mp, int how)
657 lwkt_gettoken(&ilock, &mountlist_token);
658 if (how == MNTINS_FIRST)
659 TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
661 TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
662 lwkt_reltoken(&ilock);
666 * mountlist_interlock (MP SAFE)
668 * Execute the specified interlock function with the mountlist token
669 * held. The function will be called in a serialized fashion verses
670 * other functions called through this mechanism.
673 mountlist_interlock(int (*callback)(struct mount *), struct mount *mp)
678 lwkt_gettoken(&ilock, &mountlist_token);
679 error = callback(mp);
680 lwkt_reltoken(&ilock);
685 * mountlist_boot_getfirst (DURING BOOT ONLY)
687 * This function returns the first mount on the mountlist, which is
688 * expected to be the root mount. Since no interlocks are obtained
689 * this function is only safe to use during booting.
693 mountlist_boot_getfirst(void)
695 return(TAILQ_FIRST(&mountlist));
699 * mountlist_remove (MP SAFE)
701 * Remove a node from the mountlist. If this node is the next scan node
702 * for any active mountlist scans, the active mountlist scan will be
703 * adjusted to skip the node, thus allowing removals during mountlist
707 mountlist_remove(struct mount *mp)
709 struct mountscan_info *msi;
712 lwkt_gettoken(&ilock, &mountlist_token);
713 TAILQ_FOREACH(msi, &mountscan_list, msi_entry) {
714 if (msi->msi_node == mp) {
715 if (msi->msi_how & MNTSCAN_FORWARD)
716 msi->msi_node = TAILQ_NEXT(mp, mnt_list);
718 msi->msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
721 TAILQ_REMOVE(&mountlist, mp, mnt_list);
722 lwkt_reltoken(&ilock);
726 * mountlist_scan (MP SAFE)
728 * Safely scan the mount points on the mount list. Unless otherwise
729 * specified each mount point will be busied prior to the callback and
730 * unbusied afterwords. The callback may safely remove any mount point
731 * without interfering with the scan. If the current callback
732 * mount is removed the scanner will not attempt to unbusy it.
734 * If a mount node cannot be busied it is silently skipped.
736 * The callback return value is aggregated and a total is returned. A return
737 * value of < 0 is not aggregated and will terminate the scan.
739 * MNTSCAN_FORWARD - the mountlist is scanned in the forward direction
740 * MNTSCAN_REVERSE - the mountlist is scanned in reverse
741 * MNTSCAN_NOBUSY - the scanner will make the callback without busying
745 mountlist_scan(int (*callback)(struct mount *, void *), void *data, int how)
747 struct mountscan_info info;
754 lwkt_gettoken(&ilock, &mountlist_token);
757 info.msi_node = NULL; /* paranoia */
758 TAILQ_INSERT_TAIL(&mountscan_list, &info, msi_entry);
763 if (how & MNTSCAN_FORWARD) {
764 info.msi_node = TAILQ_FIRST(&mountlist);
765 while ((mp = info.msi_node) != NULL) {
766 if (how & MNTSCAN_NOBUSY) {
767 count = callback(mp, data);
768 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
769 count = callback(mp, data);
770 if (mp == info.msi_node)
778 if (mp == info.msi_node)
779 info.msi_node = TAILQ_NEXT(mp, mnt_list);
781 } else if (how & MNTSCAN_REVERSE) {
782 info.msi_node = TAILQ_LAST(&mountlist, mntlist);
783 while ((mp = info.msi_node) != NULL) {
784 if (how & MNTSCAN_NOBUSY) {
785 count = callback(mp, data);
786 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
787 count = callback(mp, data);
788 if (mp == info.msi_node)
796 if (mp == info.msi_node)
797 info.msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
800 TAILQ_REMOVE(&mountscan_list, &info, msi_entry);
801 lwkt_reltoken(&ilock);
806 * MOUNT RELATED VNODE FUNCTIONS
809 static struct kproc_desc vnlru_kp = {
814 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp)
817 * Move a vnode from one mount queue to another.
820 insmntque(struct vnode *vp, struct mount *mp)
824 lwkt_gettoken(&ilock, &mntvnode_token);
826 * Delete from old mount point vnode list, if on one.
828 if (vp->v_mount != NULL) {
829 KASSERT(vp->v_mount->mnt_nvnodelistsize > 0,
830 ("bad mount point vnode list size"));
832 vp->v_mount->mnt_nvnodelistsize--;
835 * Insert into list of vnodes for the new mount point, if available.
837 if ((vp->v_mount = mp) == NULL) {
838 lwkt_reltoken(&ilock);
841 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
842 mp->mnt_nvnodelistsize++;
843 lwkt_reltoken(&ilock);
848 * Scan the vnodes under a mount point and issue appropriate callbacks.
850 * The fastfunc() callback is called with just the mountlist token held
851 * (no vnode lock). It may not block and the vnode may be undergoing
852 * modifications while the caller is processing it. The vnode will
853 * not be entirely destroyed, however, due to the fact that the mountlist
854 * token is held. A return value < 0 skips to the next vnode without calling
855 * the slowfunc(), a return value > 0 terminates the loop.
857 * The slowfunc() callback is called after the vnode has been successfully
858 * locked based on passed flags. The vnode is skipped if it gets rearranged
859 * or destroyed while blocking on the lock. A non-zero return value from
860 * the slow function terminates the loop. The slow function is allowed to
861 * arbitrarily block. The scanning code guarentees consistency of operation
862 * even if the slow function deletes or moves the node, or blocks and some
863 * other thread deletes or moves the node.
869 int (*fastfunc)(struct mount *mp, struct vnode *vp, void *data),
870 int (*slowfunc)(struct mount *mp, struct vnode *vp, void *data),
873 struct vmntvnodescan_info info;
877 int maxcount = 1000000;
879 lwkt_gettoken(&ilock, &mntvnode_token);
881 info.vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
882 TAILQ_INSERT_TAIL(&mntvnodescan_list, &info, entry);
883 while ((vp = info.vp) != NULL) {
885 panic("maxcount reached during vmntvnodescan");
887 if (vp->v_type == VNON) /* visible but not ready */
889 KKASSERT(vp->v_mount == mp);
892 * Quick test. A negative return continues the loop without
893 * calling the slow test. 0 continues onto the slow test.
894 * A positive number aborts the loop.
897 if ((r = fastfunc(mp, vp, data)) < 0)
904 * Get a vxlock on the vnode, retry if it has moved or isn't
905 * in the mountlist where we expect it.
912 error = vget(vp, LK_EXCLUSIVE);
914 case VMSC_GETVP|VMSC_NOWAIT:
915 error = vget(vp, LK_EXCLUSIVE|LK_NOWAIT);
928 * Do not call the slow function if the vnode is
929 * invalid or if it was ripped out from under us
930 * while we (potentially) blocked.
932 if (info.vp == vp && vp->v_type != VNON)
933 r = slowfunc(mp, vp, data);
940 case VMSC_GETVP|VMSC_NOWAIT:
954 * Iterate. If the vnode was ripped out from under us
955 * info.vp will already point to the next vnode, otherwise
956 * we have to obtain the next valid vnode ourselves.
960 info.vp = TAILQ_NEXT(vp, v_nmntvnodes);
962 TAILQ_REMOVE(&mntvnodescan_list, &info, entry);
963 lwkt_reltoken(&ilock);
968 * Remove any vnodes in the vnode table belonging to mount point mp.
970 * If FORCECLOSE is not specified, there should not be any active ones,
971 * return error if any are found (nb: this is a user error, not a
972 * system error). If FORCECLOSE is specified, detach any active vnodes
975 * If WRITECLOSE is set, only flush out regular file vnodes open for
978 * SKIPSYSTEM causes any vnodes marked VSYSTEM to be skipped.
980 * `rootrefs' specifies the base reference count for the root vnode
981 * of this filesystem. The root vnode is considered busy if its
982 * v_usecount exceeds this value. On a successful return, vflush()
983 * will call vrele() on the root vnode exactly rootrefs times.
984 * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must
988 static int busyprt = 0; /* print out busy vnodes */
989 SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, "");
992 static int vflush_scan(struct mount *mp, struct vnode *vp, void *data);
1001 vflush(struct mount *mp, int rootrefs, int flags)
1003 struct thread *td = curthread; /* XXX */
1004 struct vnode *rootvp = NULL;
1006 struct vflush_info vflush_info;
1009 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0,
1010 ("vflush: bad args"));
1012 * Get the filesystem root vnode. We can vput() it
1013 * immediately, since with rootrefs > 0, it won't go away.
1015 if ((error = VFS_ROOT(mp, &rootvp)) != 0)
1020 vflush_info.busy = 0;
1021 vflush_info.flags = flags;
1022 vflush_info.td = td;
1023 vmntvnodescan(mp, VMSC_GETVX, NULL, vflush_scan, &vflush_info);
1025 if (rootrefs > 0 && (flags & FORCECLOSE) == 0) {
1027 * If just the root vnode is busy, and if its refcount
1028 * is equal to `rootrefs', then go ahead and kill it.
1030 KASSERT(vflush_info.busy > 0, ("vflush: not busy"));
1031 KASSERT(rootvp->v_usecount >= rootrefs, ("vflush: rootrefs"));
1032 if (vflush_info.busy == 1 && rootvp->v_usecount == rootrefs) {
1036 vflush_info.busy = 0;
1039 if (vflush_info.busy)
1041 for (; rootrefs > 0; rootrefs--)
1047 * The scan callback is made with an VX locked vnode.
1050 vflush_scan(struct mount *mp, struct vnode *vp, void *data)
1052 struct vflush_info *info = data;
1056 * Skip over a vnodes marked VSYSTEM.
1058 if ((info->flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM)) {
1063 * If WRITECLOSE is set, flush out unlinked but still open
1064 * files (even if open only for reading) and regular file
1065 * vnodes open for writing.
1067 if ((info->flags & WRITECLOSE) &&
1068 (vp->v_type == VNON ||
1069 (VOP_GETATTR(vp, &vattr) == 0 &&
1070 vattr.va_nlink > 0)) &&
1071 (vp->v_writecount == 0 || vp->v_type != VREG)) {
1076 * With v_usecount == 0, all we need to do is clear out the
1077 * vnode data structures and we are done.
1079 if (vp->v_usecount == 1) {
1085 * If FORCECLOSE is set, forcibly close the vnode. For block
1086 * or character devices, revert to an anonymous device. For
1087 * all other files, just kill them.
1089 if (info->flags & FORCECLOSE) {
1090 if (vp->v_type != VBLK && vp->v_type != VCHR) {
1093 spin_lock_wr(&vp->v_spinlock);
1094 vclean_interlocked(vp, 0);
1095 /* spinlock unlocked */
1096 vp->v_ops = &spec_vnode_vops_p;
1097 insmntque(vp, NULL);
1103 vprint("vflush: busy vnode", vp);