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
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12 * notice, this list of conditions and the following disclaimer.
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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
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34 * Copyright (c) 1989, 1993
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67 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
70 * $DragonFly: src/sys/kern/vfs_mount.c,v 1.25 2007/01/12 03:05:49 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 /* note: mountlist exported to pstat */
118 struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist);
119 static TAILQ_HEAD(,mountscan_info) mountscan_list;
120 static struct lwkt_token mountlist_token;
121 static TAILQ_HEAD(,vmntvnodescan_info) mntvnodescan_list;
122 struct lwkt_token mntvnode_token;
125 * Called from vfsinit()
130 lwkt_token_init(&mountlist_token);
131 lwkt_token_init(&mntvnode_token);
132 lwkt_token_init(&mntid_token);
133 TAILQ_INIT(&mountscan_list);
134 TAILQ_INIT(&mntvnodescan_list);
138 * Support function called with mntvnode_token held to remove a vnode
139 * from the mountlist. We must update any list scans which are in progress.
142 vremovevnodemnt(struct vnode *vp)
144 struct vmntvnodescan_info *info;
146 TAILQ_FOREACH(info, &mntvnodescan_list, entry) {
148 info->vp = TAILQ_NEXT(vp, v_nmntvnodes);
150 TAILQ_REMOVE(&vp->v_mount->mnt_nvnodelist, vp, v_nmntvnodes);
154 * Support function called with mntvnode_token held to move a vnode to
155 * the end of the list.
158 vmovevnodetoend(struct mount *mp, struct vnode *vp)
161 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
166 * Allocate a new vnode and associate it with a tag, mount point, and
169 * A VX locked and refd vnode is returned. The caller should setup the
170 * remaining fields and vx_put() or, if he wishes to leave a vref,
171 * vx_unlock() the vnode.
174 getnewvnode(enum vtagtype tag, struct mount *mp,
175 struct vnode **vpp, int lktimeout, int lkflags)
179 KKASSERT(mp != NULL);
181 vp = allocvnode(lktimeout, lkflags);
186 * By default the vnode is assigned the mount point's normal
189 vp->v_ops = &mp->mnt_vn_use_ops;
192 * Placing the vnode on the mount point's queue makes it visible.
193 * VNON prevents it from being messed with, however.
198 * A VX locked & refd vnode is returned.
205 * This function creates vnodes with special operations vectors. The
206 * mount point is optional.
208 * This routine is being phased out.
211 getspecialvnode(enum vtagtype tag, struct mount *mp,
212 struct vop_ops **ops,
213 struct vnode **vpp, int lktimeout, int lkflags)
217 vp = allocvnode(lktimeout, lkflags);
223 * Placing the vnode on the mount point's queue makes it visible.
224 * VNON prevents it from being messed with, however.
229 * A VX locked & refd vnode is returned.
236 * Interlock against an unmount, return 0 on success, non-zero on failure.
238 * The passed flag may be 0 or LK_NOWAIT and is only used if an unmount
241 * If no unmount is in-progress LK_NOWAIT is ignored. No other flag bits
242 * are used. A shared locked will be obtained and the filesystem will not
243 * be unmountable until the lock is released.
246 vfs_busy(struct mount *mp, int flags)
250 if (mp->mnt_kern_flag & MNTK_UNMOUNT) {
251 if (flags & LK_NOWAIT)
253 /* XXX not MP safe */
254 mp->mnt_kern_flag |= MNTK_MWAIT;
256 * Since all busy locks are shared except the exclusive
257 * lock granted when unmounting, the only place that a
258 * wakeup needs to be done is at the release of the
259 * exclusive lock at the end of dounmount.
261 tsleep((caddr_t)mp, 0, "vfs_busy", 0);
265 if (lockmgr(&mp->mnt_lock, lkflags))
266 panic("vfs_busy: unexpected lock failure");
271 * Free a busy filesystem.
274 vfs_unbusy(struct mount *mp)
276 lockmgr(&mp->mnt_lock, LK_RELEASE);
280 * Lookup a filesystem type, and if found allocate and initialize
281 * a mount structure for it.
283 * Devname is usually updated by mount(8) after booting.
286 vfs_rootmountalloc(char *fstypename, char *devname, struct mount **mpp)
288 struct vfsconf *vfsp;
291 if (fstypename == NULL)
293 for (vfsp = vfsconf; vfsp; vfsp = vfsp->vfc_next) {
294 if (!strcmp(vfsp->vfc_name, fstypename))
299 mp = kmalloc(sizeof(struct mount), M_MOUNT, M_WAITOK);
300 bzero((char *)mp, (u_long)sizeof(struct mount));
301 lockinit(&mp->mnt_lock, "vfslock", VLKTIMEOUT, 0);
302 vfs_busy(mp, LK_NOWAIT);
303 TAILQ_INIT(&mp->mnt_nvnodelist);
304 TAILQ_INIT(&mp->mnt_reservedvnlist);
305 TAILQ_INIT(&mp->mnt_jlist);
306 mp->mnt_nvnodelistsize = 0;
308 mp->mnt_op = vfsp->vfc_vfsops;
309 mp->mnt_flag = MNT_RDONLY;
310 vfsp->vfc_refcount++;
311 mp->mnt_iosize_max = DFLTPHYS;
312 mp->mnt_stat.f_type = vfsp->vfc_typenum;
313 mp->mnt_flag |= vfsp->vfc_flags & MNT_VISFLAGMASK;
314 strncpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN);
315 copystr(devname, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 0);
321 * Lookup a mount point by filesystem identifier.
324 vfs_getvfs(fsid_t *fsid)
329 lwkt_gettoken(&ilock, &mountlist_token);
330 TAILQ_FOREACH(mp, &mountlist, mnt_list) {
331 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
332 mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
336 lwkt_reltoken(&ilock);
341 * Get a new unique fsid. Try to make its val[0] unique, since this value
342 * will be used to create fake device numbers for stat(). Also try (but
343 * not so hard) make its val[0] unique mod 2^16, since some emulators only
344 * support 16-bit device numbers. We end up with unique val[0]'s for the
345 * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls.
347 * Keep in mind that several mounts may be running in parallel. Starting
348 * the search one past where the previous search terminated is both a
349 * micro-optimization and a defense against returning the same fsid to
353 vfs_getnewfsid(struct mount *mp)
355 static u_int16_t mntid_base;
360 lwkt_gettoken(&ilock, &mntid_token);
361 mtype = mp->mnt_vfc->vfc_typenum;
362 tfsid.val[1] = mtype;
363 mtype = (mtype & 0xFF) << 24;
365 tfsid.val[0] = makeudev(255,
366 mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF));
368 if (vfs_getvfs(&tfsid) == NULL)
371 mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
372 mp->mnt_stat.f_fsid.val[1] = tfsid.val[1];
373 lwkt_reltoken(&ilock);
377 * This routine is called when we have too many vnodes. It attempts
378 * to free <count> vnodes and will potentially free vnodes that still
379 * have VM backing store (VM backing store is typically the cause
380 * of a vnode blowout so we want to do this). Therefore, this operation
381 * is not considered cheap.
383 * A number of conditions may prevent a vnode from being reclaimed.
384 * the buffer cache may have references on the vnode, a directory
385 * vnode may still have references due to the namei cache representing
386 * underlying files, or the vnode may be in active use. It is not
387 * desireable to reuse such vnodes. These conditions may cause the
388 * number of vnodes to reach some minimum value regardless of what
389 * you set kern.maxvnodes to. Do not set kern.maxvnodes too low.
393 * This is a quick non-blocking check to determine if the vnode is a good
394 * candidate for being (eventually) vgone()'d. Returns 0 if the vnode is
395 * not a good candidate, 1 if it is.
397 * Note that a vnode can be marked VFREE without really being free, so
398 * we don't use the flag for any tests.
401 vmightfree(struct vnode *vp, int page_count)
403 if (vp->v_flag & VRECLAIMED)
406 if ((vp->v_flag & VFREE) && TAILQ_EMPTY(&vp->v_namecache))
409 if (vp->v_usecount != 0)
411 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
417 * The vnode was found to be possibly vgone()able and the caller has locked it
418 * (thus the usecount should be 1 now). Determine if the vnode is actually
419 * vgone()able, doing some cleanups in the process. Returns 1 if the vnode
420 * can be vgone()'d, 0 otherwise.
422 * Note that v_holdcnt may be non-zero because (A) this vnode is not a leaf
423 * in the namecache topology and (B) this vnode has buffer cache bufs.
424 * We cannot remove vnodes with non-leaf namecache associations. We do a
425 * tentitive leaf check prior to attempting to flush out any buffers but the
426 * 'real' test when all is said in done is that v_holdcnt must become 0 for
427 * the vnode to be freeable.
429 * We could theoretically just unconditionally flush when v_holdcnt != 0,
430 * but flushing data associated with non-leaf nodes (which are always
431 * directories), just throws it away for no benefit. It is the buffer
432 * cache's responsibility to choose buffers to recycle from the cached
433 * data point of view.
436 visleaf(struct vnode *vp)
438 struct namecache *ncp;
440 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
441 if (!TAILQ_EMPTY(&ncp->nc_list))
448 * Try to clean up the vnode to the point where it can be vgone()'d, returning
449 * 0 if it cannot be vgone()'d (or already has been), 1 if it can. Unlike
450 * vmightfree() this routine may flush the vnode and block. Vnodes marked
451 * VFREE are still candidates for vgone()ing because they may hold namecache
452 * resources and could be blocking the namecache directory hierarchy (and
453 * related vnodes) from being freed.
456 vtrytomakegoneable(struct vnode *vp, int page_count)
458 if (vp->v_flag & VRECLAIMED)
460 if (vp->v_usecount != 1)
462 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
464 if (vp->v_holdcnt && visleaf(vp)) {
465 vinvalbuf(vp, V_SAVE, 0, 0);
467 kprintf((vp->v_holdcnt ? "vrecycle: vp %p failed: %s\n" :
468 "vrecycle: vp %p succeeded: %s\n"), vp,
469 (TAILQ_FIRST(&vp->v_namecache) ?
470 TAILQ_FIRST(&vp->v_namecache)->nc_name : "?"));
473 return(vp->v_usecount == 1 && vp->v_holdcnt == 0);
477 * Reclaim up to 1/10 of the vnodes associated with a mount point. Try
478 * to avoid vnodes which have lots of resident pages (we are trying to free
479 * vnodes, not memory).
481 * This routine is a callback from the mountlist scan. The mount point
482 * in question will be busied.
485 vlrureclaim(struct mount *mp, void *data)
493 int trigger_mult = vnlru_nowhere;
496 * Calculate the trigger point for the resident pages check. The
497 * minimum trigger value is approximately the number of pages in
498 * the system divded by the number of vnodes. However, due to
499 * various other system memory overheads unrelated to data caching
500 * it is a good idea to double the trigger (at least).
502 * trigger_mult starts at 0. If the recycler is having problems
503 * finding enough freeable vnodes it will increase trigger_mult.
504 * This should not happen in normal operation, even on machines with
505 * low amounts of memory, but extraordinary memory use by the system
506 * verses the amount of cached data can trigger it.
508 usevnodes = desiredvnodes;
511 trigger = vmstats.v_page_count * (trigger_mult + 2) / usevnodes;
514 lwkt_gettoken(&ilock, &mntvnode_token);
515 count = mp->mnt_nvnodelistsize / 10 + 1;
516 while (count && (vp = TAILQ_FIRST(&mp->mnt_nvnodelist)) != NULL) {
520 * The VP will stick around while we hold mntvnode_token,
521 * at least until we block, so we can safely do an initial
522 * check, and then must check again after we lock the vnode.
524 if (vp->v_type == VNON || /* XXX */
525 vp->v_type == VBAD || /* XXX */
526 !vmightfree(vp, trigger) /* critical path opt */
528 vmovevnodetoend(mp, vp);
534 * VX get the candidate vnode. If the VX get fails the
535 * vnode might still be on the mountlist. Our loop depends
536 * on us at least cycling the vnode to the end of the
539 if (vx_get_nonblock(vp) != 0) {
540 if (vp->v_mount == mp)
541 vmovevnodetoend(mp, vp);
547 * Since we blocked locking the vp, make sure it is still
548 * a candidate for reclamation. That is, it has not already
549 * been reclaimed and only has our VX reference associated
552 if (vp->v_type == VNON || /* XXX */
553 vp->v_type == VBAD || /* XXX */
554 (vp->v_flag & VRECLAIMED) ||
556 !vtrytomakegoneable(vp, trigger) /* critical path opt */
558 if (vp->v_mount == mp)
559 vmovevnodetoend(mp, vp);
566 * All right, we are good, move the vp to the end of the
567 * mountlist and clean it out. The vget will have returned
568 * an error if the vnode was destroyed (VRECLAIMED set), so we
569 * do not have to check again. The vput() will move the
570 * vnode to the free list if the vgone() was successful.
572 KKASSERT(vp->v_mount == mp);
573 vmovevnodetoend(mp, vp);
579 lwkt_reltoken(&ilock);
584 * Attempt to recycle vnodes in a context that is always safe to block.
585 * Calling vlrurecycle() from the bowels of file system code has some
586 * interesting deadlock problems.
588 static struct thread *vnlruthread;
589 static int vnlruproc_sig;
592 vnlru_proc_wait(void)
594 if (vnlruproc_sig == 0) {
595 vnlruproc_sig = 1; /* avoid unnecessary wakeups */
598 tsleep(&vnlruproc_sig, 0, "vlruwk", hz);
604 struct thread *td = curthread;
607 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td,
612 kproc_suspend_loop();
613 if (numvnodes - freevnodes <= desiredvnodes * 9 / 10) {
615 wakeup(&vnlruproc_sig);
616 tsleep(td, 0, "vlruwt", hz);
620 done = mountlist_scan(vlrureclaim, NULL, MNTSCAN_FORWARD);
623 * The vlrureclaim() call only processes 1/10 of the vnodes
624 * on each mount. If we couldn't find any repeat the loop
625 * at least enough times to cover all available vnodes before
626 * we start sleeping. Complain if the failure extends past
627 * 30 second, every 30 seconds.
631 if (vnlru_nowhere % 10 == 0)
632 tsleep(td, 0, "vlrup", hz * 3);
633 if (vnlru_nowhere % 100 == 0)
634 kprintf("vnlru_proc: vnode recycler stopped working!\n");
635 if (vnlru_nowhere == 1000)
645 * MOUNTLIST FUNCTIONS
649 * mountlist_insert (MP SAFE)
651 * Add a new mount point to the mount list.
654 mountlist_insert(struct mount *mp, int how)
658 lwkt_gettoken(&ilock, &mountlist_token);
659 if (how == MNTINS_FIRST)
660 TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
662 TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
663 lwkt_reltoken(&ilock);
667 * mountlist_interlock (MP SAFE)
669 * Execute the specified interlock function with the mountlist token
670 * held. The function will be called in a serialized fashion verses
671 * other functions called through this mechanism.
674 mountlist_interlock(int (*callback)(struct mount *), struct mount *mp)
679 lwkt_gettoken(&ilock, &mountlist_token);
680 error = callback(mp);
681 lwkt_reltoken(&ilock);
686 * mountlist_boot_getfirst (DURING BOOT ONLY)
688 * This function returns the first mount on the mountlist, which is
689 * expected to be the root mount. Since no interlocks are obtained
690 * this function is only safe to use during booting.
694 mountlist_boot_getfirst(void)
696 return(TAILQ_FIRST(&mountlist));
700 * mountlist_remove (MP SAFE)
702 * Remove a node from the mountlist. If this node is the next scan node
703 * for any active mountlist scans, the active mountlist scan will be
704 * adjusted to skip the node, thus allowing removals during mountlist
708 mountlist_remove(struct mount *mp)
710 struct mountscan_info *msi;
713 lwkt_gettoken(&ilock, &mountlist_token);
714 TAILQ_FOREACH(msi, &mountscan_list, msi_entry) {
715 if (msi->msi_node == mp) {
716 if (msi->msi_how & MNTSCAN_FORWARD)
717 msi->msi_node = TAILQ_NEXT(mp, mnt_list);
719 msi->msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
722 TAILQ_REMOVE(&mountlist, mp, mnt_list);
723 lwkt_reltoken(&ilock);
727 * mountlist_scan (MP SAFE)
729 * Safely scan the mount points on the mount list. Unless otherwise
730 * specified each mount point will be busied prior to the callback and
731 * unbusied afterwords. The callback may safely remove any mount point
732 * without interfering with the scan. If the current callback
733 * mount is removed the scanner will not attempt to unbusy it.
735 * If a mount node cannot be busied it is silently skipped.
737 * The callback return value is aggregated and a total is returned. A return
738 * value of < 0 is not aggregated and will terminate the scan.
740 * MNTSCAN_FORWARD - the mountlist is scanned in the forward direction
741 * MNTSCAN_REVERSE - the mountlist is scanned in reverse
742 * MNTSCAN_NOBUSY - the scanner will make the callback without busying
746 mountlist_scan(int (*callback)(struct mount *, void *), void *data, int how)
748 struct mountscan_info info;
755 lwkt_gettoken(&ilock, &mountlist_token);
758 info.msi_node = NULL; /* paranoia */
759 TAILQ_INSERT_TAIL(&mountscan_list, &info, msi_entry);
764 if (how & MNTSCAN_FORWARD) {
765 info.msi_node = TAILQ_FIRST(&mountlist);
766 while ((mp = info.msi_node) != NULL) {
767 if (how & MNTSCAN_NOBUSY) {
768 count = callback(mp, data);
769 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
770 count = callback(mp, data);
771 if (mp == info.msi_node)
779 if (mp == info.msi_node)
780 info.msi_node = TAILQ_NEXT(mp, mnt_list);
782 } else if (how & MNTSCAN_REVERSE) {
783 info.msi_node = TAILQ_LAST(&mountlist, mntlist);
784 while ((mp = info.msi_node) != NULL) {
785 if (how & MNTSCAN_NOBUSY) {
786 count = callback(mp, data);
787 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
788 count = callback(mp, data);
789 if (mp == info.msi_node)
797 if (mp == info.msi_node)
798 info.msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
801 TAILQ_REMOVE(&mountscan_list, &info, msi_entry);
802 lwkt_reltoken(&ilock);
807 * MOUNT RELATED VNODE FUNCTIONS
810 static struct kproc_desc vnlru_kp = {
815 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp)
818 * Move a vnode from one mount queue to another.
821 insmntque(struct vnode *vp, struct mount *mp)
825 lwkt_gettoken(&ilock, &mntvnode_token);
827 * Delete from old mount point vnode list, if on one.
829 if (vp->v_mount != NULL) {
830 KASSERT(vp->v_mount->mnt_nvnodelistsize > 0,
831 ("bad mount point vnode list size"));
833 vp->v_mount->mnt_nvnodelistsize--;
836 * Insert into list of vnodes for the new mount point, if available.
838 if ((vp->v_mount = mp) == NULL) {
839 lwkt_reltoken(&ilock);
842 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
843 mp->mnt_nvnodelistsize++;
844 lwkt_reltoken(&ilock);
849 * Scan the vnodes under a mount point and issue appropriate callbacks.
851 * The fastfunc() callback is called with just the mountlist token held
852 * (no vnode lock). It may not block and the vnode may be undergoing
853 * modifications while the caller is processing it. The vnode will
854 * not be entirely destroyed, however, due to the fact that the mountlist
855 * token is held. A return value < 0 skips to the next vnode without calling
856 * the slowfunc(), a return value > 0 terminates the loop.
858 * The slowfunc() callback is called after the vnode has been successfully
859 * locked based on passed flags. The vnode is skipped if it gets rearranged
860 * or destroyed while blocking on the lock. A non-zero return value from
861 * the slow function terminates the loop. The slow function is allowed to
862 * arbitrarily block. The scanning code guarentees consistency of operation
863 * even if the slow function deletes or moves the node, or blocks and some
864 * other thread deletes or moves the node.
870 int (*fastfunc)(struct mount *mp, struct vnode *vp, void *data),
871 int (*slowfunc)(struct mount *mp, struct vnode *vp, void *data),
874 struct vmntvnodescan_info info;
878 int maxcount = 1000000;
880 lwkt_gettoken(&ilock, &mntvnode_token);
882 info.vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
883 TAILQ_INSERT_TAIL(&mntvnodescan_list, &info, entry);
884 while ((vp = info.vp) != NULL) {
886 panic("maxcount reached during vmntvnodescan");
888 if (vp->v_type == VNON) /* visible but not ready */
890 KKASSERT(vp->v_mount == mp);
893 * Quick test. A negative return continues the loop without
894 * calling the slow test. 0 continues onto the slow test.
895 * A positive number aborts the loop.
898 if ((r = fastfunc(mp, vp, data)) < 0)
905 * Get a vxlock on the vnode, retry if it has moved or isn't
906 * in the mountlist where we expect it.
913 error = vget(vp, LK_EXCLUSIVE);
915 case VMSC_GETVP|VMSC_NOWAIT:
916 error = vget(vp, LK_EXCLUSIVE|LK_NOWAIT);
929 * Do not call the slow function if the vnode is
930 * invalid or if it was ripped out from under us
931 * while we (potentially) blocked.
933 if (info.vp == vp && vp->v_type != VNON)
934 r = slowfunc(mp, vp, data);
941 case VMSC_GETVP|VMSC_NOWAIT:
955 * Iterate. If the vnode was ripped out from under us
956 * info.vp will already point to the next vnode, otherwise
957 * we have to obtain the next valid vnode ourselves.
961 info.vp = TAILQ_NEXT(vp, v_nmntvnodes);
963 TAILQ_REMOVE(&mntvnodescan_list, &info, entry);
964 lwkt_reltoken(&ilock);
969 * Remove any vnodes in the vnode table belonging to mount point mp.
971 * If FORCECLOSE is not specified, there should not be any active ones,
972 * return error if any are found (nb: this is a user error, not a
973 * system error). If FORCECLOSE is specified, detach any active vnodes
976 * If WRITECLOSE is set, only flush out regular file vnodes open for
979 * SKIPSYSTEM causes any vnodes marked VSYSTEM to be skipped.
981 * `rootrefs' specifies the base reference count for the root vnode
982 * of this filesystem. The root vnode is considered busy if its
983 * v_usecount exceeds this value. On a successful return, vflush()
984 * will call vrele() on the root vnode exactly rootrefs times.
985 * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must
989 static int busyprt = 0; /* print out busy vnodes */
990 SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, "");
993 static int vflush_scan(struct mount *mp, struct vnode *vp, void *data);
1002 vflush(struct mount *mp, int rootrefs, int flags)
1004 struct thread *td = curthread; /* XXX */
1005 struct vnode *rootvp = NULL;
1007 struct vflush_info vflush_info;
1010 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0,
1011 ("vflush: bad args"));
1013 * Get the filesystem root vnode. We can vput() it
1014 * immediately, since with rootrefs > 0, it won't go away.
1016 if ((error = VFS_ROOT(mp, &rootvp)) != 0)
1021 vflush_info.busy = 0;
1022 vflush_info.flags = flags;
1023 vflush_info.td = td;
1024 vmntvnodescan(mp, VMSC_GETVX, NULL, vflush_scan, &vflush_info);
1026 if (rootrefs > 0 && (flags & FORCECLOSE) == 0) {
1028 * If just the root vnode is busy, and if its refcount
1029 * is equal to `rootrefs', then go ahead and kill it.
1031 KASSERT(vflush_info.busy > 0, ("vflush: not busy"));
1032 KASSERT(rootvp->v_usecount >= rootrefs, ("vflush: rootrefs"));
1033 if (vflush_info.busy == 1 && rootvp->v_usecount == rootrefs) {
1037 vflush_info.busy = 0;
1040 if (vflush_info.busy)
1042 for (; rootrefs > 0; rootrefs--)
1048 * The scan callback is made with an VX locked vnode.
1051 vflush_scan(struct mount *mp, struct vnode *vp, void *data)
1053 struct vflush_info *info = data;
1057 * Skip over a vnodes marked VSYSTEM.
1059 if ((info->flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM)) {
1064 * If WRITECLOSE is set, flush out unlinked but still open
1065 * files (even if open only for reading) and regular file
1066 * vnodes open for writing.
1068 if ((info->flags & WRITECLOSE) &&
1069 (vp->v_type == VNON ||
1070 (VOP_GETATTR(vp, &vattr) == 0 &&
1071 vattr.va_nlink > 0)) &&
1072 (vp->v_writecount == 0 || vp->v_type != VREG)) {
1077 * With v_usecount == 0, all we need to do is clear out the
1078 * vnode data structures and we are done.
1080 if (vp->v_usecount == 1) {
1086 * If FORCECLOSE is set, forcibly close the vnode. For block
1087 * or character devices, revert to an anonymous device. For
1088 * all other files, just kill them.
1090 if (info->flags & FORCECLOSE) {
1091 if (vp->v_type != VBLK && vp->v_type != VCHR) {
1094 spin_lock_wr(&vp->v_spinlock);
1095 vclean_interlocked(vp, 0);
1096 /* spinlock unlocked */
1097 vp->v_ops = &spec_vnode_vops_p;
1098 insmntque(vp, NULL);
1104 vprint("vflush: busy vnode", vp);