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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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.
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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 1.34 2008/05/18 21:47:02 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;
110 static int vnlru_nowhere = 0;
111 SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhere, CTLFLAG_RD,
113 "Number of times the vnlru process ran without success");
116 static struct lwkt_token mntid_token;
118 /* note: mountlist exported to pstat */
119 struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist);
120 static TAILQ_HEAD(,mountscan_info) mountscan_list;
121 static struct lwkt_token mountlist_token;
122 static TAILQ_HEAD(,vmntvnodescan_info) mntvnodescan_list;
123 struct lwkt_token mntvnode_token;
125 static TAILQ_HEAD(,bio_ops) bio_ops_list = TAILQ_HEAD_INITIALIZER(bio_ops_list);
128 * Called from vfsinit()
133 lwkt_token_init(&mountlist_token);
134 lwkt_token_init(&mntvnode_token);
135 lwkt_token_init(&mntid_token);
136 TAILQ_INIT(&mountscan_list);
137 TAILQ_INIT(&mntvnodescan_list);
141 * Support function called with mntvnode_token held to remove a vnode
142 * from the mountlist. We must update any list scans which are in progress.
145 vremovevnodemnt(struct vnode *vp)
147 struct vmntvnodescan_info *info;
149 TAILQ_FOREACH(info, &mntvnodescan_list, entry) {
151 info->vp = TAILQ_NEXT(vp, v_nmntvnodes);
153 TAILQ_REMOVE(&vp->v_mount->mnt_nvnodelist, vp, v_nmntvnodes);
157 * Allocate a new vnode and associate it with a tag, mount point, and
160 * A VX locked and refd vnode is returned. The caller should setup the
161 * remaining fields and vx_put() or, if he wishes to leave a vref,
162 * vx_unlock() the vnode.
165 getnewvnode(enum vtagtype tag, struct mount *mp,
166 struct vnode **vpp, int lktimeout, int lkflags)
170 KKASSERT(mp != NULL);
172 vp = allocvnode(lktimeout, lkflags);
177 * By default the vnode is assigned the mount point's normal
180 vp->v_ops = &mp->mnt_vn_use_ops;
183 * Placing the vnode on the mount point's queue makes it visible.
184 * VNON prevents it from being messed with, however.
189 * A VX locked & refd vnode is returned.
196 * This function creates vnodes with special operations vectors. The
197 * mount point is optional.
199 * This routine is being phased out.
202 getspecialvnode(enum vtagtype tag, struct mount *mp,
203 struct vop_ops **ops,
204 struct vnode **vpp, int lktimeout, int lkflags)
208 vp = allocvnode(lktimeout, lkflags);
214 * Placing the vnode on the mount point's queue makes it visible.
215 * VNON prevents it from being messed with, however.
220 * A VX locked & refd vnode is returned.
227 * Interlock against an unmount, return 0 on success, non-zero on failure.
229 * The passed flag may be 0 or LK_NOWAIT and is only used if an unmount
232 * If no unmount is in-progress LK_NOWAIT is ignored. No other flag bits
233 * are used. A shared locked will be obtained and the filesystem will not
234 * be unmountable until the lock is released.
237 vfs_busy(struct mount *mp, int flags)
241 if (mp->mnt_kern_flag & MNTK_UNMOUNT) {
242 if (flags & LK_NOWAIT)
244 /* XXX not MP safe */
245 mp->mnt_kern_flag |= MNTK_MWAIT;
247 * Since all busy locks are shared except the exclusive
248 * lock granted when unmounting, the only place that a
249 * wakeup needs to be done is at the release of the
250 * exclusive lock at the end of dounmount.
252 tsleep((caddr_t)mp, 0, "vfs_busy", 0);
256 if (lockmgr(&mp->mnt_lock, lkflags))
257 panic("vfs_busy: unexpected lock failure");
262 * Free a busy filesystem.
265 vfs_unbusy(struct mount *mp)
267 lockmgr(&mp->mnt_lock, LK_RELEASE);
271 * Lookup a filesystem type, and if found allocate and initialize
272 * a mount structure for it.
274 * Devname is usually updated by mount(8) after booting.
277 vfs_rootmountalloc(char *fstypename, char *devname, struct mount **mpp)
279 struct vfsconf *vfsp;
282 if (fstypename == NULL)
284 for (vfsp = vfsconf; vfsp; vfsp = vfsp->vfc_next) {
285 if (!strcmp(vfsp->vfc_name, fstypename))
290 mp = kmalloc(sizeof(struct mount), M_MOUNT, M_WAITOK | M_ZERO);
291 lockinit(&mp->mnt_lock, "vfslock", VLKTIMEOUT, 0);
292 vfs_busy(mp, LK_NOWAIT);
293 TAILQ_INIT(&mp->mnt_nvnodelist);
294 TAILQ_INIT(&mp->mnt_reservedvnlist);
295 TAILQ_INIT(&mp->mnt_jlist);
296 mp->mnt_nvnodelistsize = 0;
298 mp->mnt_op = vfsp->vfc_vfsops;
299 mp->mnt_flag = MNT_RDONLY;
300 vfsp->vfc_refcount++;
301 mp->mnt_iosize_max = DFLTPHYS;
302 mp->mnt_stat.f_type = vfsp->vfc_typenum;
303 mp->mnt_flag |= vfsp->vfc_flags & MNT_VISFLAGMASK;
304 strncpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN);
305 copystr(devname, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 0);
311 * Lookup a mount point by filesystem identifier.
314 vfs_getvfs(fsid_t *fsid)
319 lwkt_gettoken(&ilock, &mountlist_token);
320 TAILQ_FOREACH(mp, &mountlist, mnt_list) {
321 if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
322 mp->mnt_stat.f_fsid.val[1] == fsid->val[1]) {
326 lwkt_reltoken(&ilock);
331 * Get a new unique fsid. Try to make its val[0] unique, since this value
332 * will be used to create fake device numbers for stat(). Also try (but
333 * not so hard) make its val[0] unique mod 2^16, since some emulators only
334 * support 16-bit device numbers. We end up with unique val[0]'s for the
335 * first 2^16 calls and unique val[0]'s mod 2^16 for the first 2^8 calls.
337 * Keep in mind that several mounts may be running in parallel. Starting
338 * the search one past where the previous search terminated is both a
339 * micro-optimization and a defense against returning the same fsid to
343 vfs_getnewfsid(struct mount *mp)
345 static u_int16_t mntid_base;
350 lwkt_gettoken(&ilock, &mntid_token);
351 mtype = mp->mnt_vfc->vfc_typenum;
352 tfsid.val[1] = mtype;
353 mtype = (mtype & 0xFF) << 24;
355 tfsid.val[0] = makeudev(255,
356 mtype | ((mntid_base & 0xFF00) << 8) | (mntid_base & 0xFF));
358 if (vfs_getvfs(&tfsid) == NULL)
361 mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
362 mp->mnt_stat.f_fsid.val[1] = tfsid.val[1];
363 lwkt_reltoken(&ilock);
367 * This routine is called when we have too many vnodes. It attempts
368 * to free <count> vnodes and will potentially free vnodes that still
369 * have VM backing store (VM backing store is typically the cause
370 * of a vnode blowout so we want to do this). Therefore, this operation
371 * is not considered cheap.
373 * A number of conditions may prevent a vnode from being reclaimed.
374 * the buffer cache may have references on the vnode, a directory
375 * vnode may still have references due to the namei cache representing
376 * underlying files, or the vnode may be in active use. It is not
377 * desireable to reuse such vnodes. These conditions may cause the
378 * number of vnodes to reach some minimum value regardless of what
379 * you set kern.maxvnodes to. Do not set kern.maxvnodes too low.
383 * This is a quick non-blocking check to determine if the vnode is a good
384 * candidate for being (eventually) vgone()'d. Returns 0 if the vnode is
385 * not a good candidate, 1 if it is.
388 vmightfree(struct vnode *vp, int page_count)
390 if (vp->v_flag & VRECLAIMED)
393 if ((vp->v_flag & VFREE) && TAILQ_EMPTY(&vp->v_namecache))
396 if (sysref_isactive(&vp->v_sysref))
398 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
404 * The vnode was found to be possibly vgone()able and the caller has locked it
405 * (thus the usecount should be 1 now). Determine if the vnode is actually
406 * vgone()able, doing some cleanups in the process. Returns 1 if the vnode
407 * can be vgone()'d, 0 otherwise.
409 * Note that v_auxrefs may be non-zero because (A) this vnode is not a leaf
410 * in the namecache topology and (B) this vnode has buffer cache bufs.
411 * We cannot remove vnodes with non-leaf namecache associations. We do a
412 * tentitive leaf check prior to attempting to flush out any buffers but the
413 * 'real' test when all is said in done is that v_auxrefs must become 0 for
414 * the vnode to be freeable.
416 * We could theoretically just unconditionally flush when v_auxrefs != 0,
417 * but flushing data associated with non-leaf nodes (which are always
418 * directories), just throws it away for no benefit. It is the buffer
419 * cache's responsibility to choose buffers to recycle from the cached
420 * data point of view.
423 visleaf(struct vnode *vp)
425 struct namecache *ncp;
427 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
428 if (!TAILQ_EMPTY(&ncp->nc_list))
435 * Try to clean up the vnode to the point where it can be vgone()'d, returning
436 * 0 if it cannot be vgone()'d (or already has been), 1 if it can. Unlike
437 * vmightfree() this routine may flush the vnode and block. Vnodes marked
438 * VFREE are still candidates for vgone()ing because they may hold namecache
439 * resources and could be blocking the namecache directory hierarchy (and
440 * related vnodes) from being freed.
443 vtrytomakegoneable(struct vnode *vp, int page_count)
445 if (vp->v_flag & VRECLAIMED)
447 if (vp->v_sysref.refcnt > 1)
449 if (vp->v_object && vp->v_object->resident_page_count >= page_count)
451 if (vp->v_auxrefs && visleaf(vp)) {
452 vinvalbuf(vp, V_SAVE, 0, 0);
454 kprintf((vp->v_auxrefs ? "vrecycle: vp %p failed: %s\n" :
455 "vrecycle: vp %p succeeded: %s\n"), vp,
456 (TAILQ_FIRST(&vp->v_namecache) ?
457 TAILQ_FIRST(&vp->v_namecache)->nc_name : "?"));
462 * This sequence may seem a little strange, but we need to optimize
463 * the critical path a bit. We can't recycle vnodes with other
464 * references and because we are trying to recycle an otherwise
465 * perfectly fine vnode we have to invalidate the namecache in a
466 * way that avoids possible deadlocks (since the vnode lock is being
467 * held here). Finally, we have to check for other references one
468 * last time in case something snuck in during the inval.
470 if (vp->v_sysref.refcnt > 1 || vp->v_auxrefs != 0)
472 if (cache_inval_vp_nonblock(vp))
474 return (vp->v_sysref.refcnt <= 1 && vp->v_auxrefs == 0);
478 * Reclaim up to 1/10 of the vnodes associated with a mount point. Try
479 * to avoid vnodes which have lots of resident pages (we are trying to free
480 * vnodes, not memory).
482 * This routine is a callback from the mountlist scan. The mount point
483 * in question will be busied.
486 vlrureclaim(struct mount *mp, void *data)
494 int trigger_mult = vnlru_nowhere;
497 * Calculate the trigger point for the resident pages check. The
498 * minimum trigger value is approximately the number of pages in
499 * the system divded by the number of vnodes. However, due to
500 * various other system memory overheads unrelated to data caching
501 * it is a good idea to double the trigger (at least).
503 * trigger_mult starts at 0. If the recycler is having problems
504 * finding enough freeable vnodes it will increase trigger_mult.
505 * This should not happen in normal operation, even on machines with
506 * low amounts of memory, but extraordinary memory use by the system
507 * verses the amount of cached data can trigger it.
509 usevnodes = desiredvnodes;
512 trigger = vmstats.v_page_count * (trigger_mult + 2) / usevnodes;
515 lwkt_gettoken(&ilock, &mntvnode_token);
516 count = mp->mnt_nvnodelistsize / 10 + 1;
517 while (count && mp->mnt_syncer) {
519 * Next vnode. Use the special syncer vnode to placemark
520 * the LRU. This way the LRU code does not interfere with
523 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes);
524 TAILQ_REMOVE(&mp->mnt_nvnodelist, mp->mnt_syncer, v_nmntvnodes);
526 TAILQ_INSERT_AFTER(&mp->mnt_nvnodelist, vp,
527 mp->mnt_syncer, v_nmntvnodes);
529 TAILQ_INSERT_HEAD(&mp->mnt_nvnodelist, mp->mnt_syncer,
531 vp = TAILQ_NEXT(mp->mnt_syncer, v_nmntvnodes);
539 * The VP will stick around while we hold mntvnode_token,
540 * at least until we block, so we can safely do an initial
541 * check, and then must check again after we lock the vnode.
543 if (vp->v_type == VNON || /* syncer or indeterminant */
544 !vmightfree(vp, trigger) /* critical path opt */
551 * VX get the candidate vnode. If the VX get fails the
552 * vnode might still be on the mountlist. Our loop depends
553 * on us at least cycling the vnode to the end of the
556 if (vx_get_nonblock(vp) != 0) {
562 * Since we blocked locking the vp, make sure it is still
563 * a candidate for reclamation. That is, it has not already
564 * been reclaimed and only has our VX reference associated
567 if (vp->v_type == VNON || /* syncer or indeterminant */
568 (vp->v_flag & VRECLAIMED) ||
570 !vtrytomakegoneable(vp, trigger) /* critical path opt */
578 * All right, we are good, move the vp to the end of the
579 * mountlist and clean it out. The vget will have returned
580 * an error if the vnode was destroyed (VRECLAIMED set), so we
581 * do not have to check again. The vput() will move the
582 * vnode to the free list if the vgone() was successful.
584 KKASSERT(vp->v_mount == mp);
590 lwkt_reltoken(&ilock);
595 * Attempt to recycle vnodes in a context that is always safe to block.
596 * Calling vlrurecycle() from the bowels of file system code has some
597 * interesting deadlock problems.
599 static struct thread *vnlruthread;
600 static int vnlruproc_sig;
603 vnlru_proc_wait(void)
605 if (vnlruproc_sig == 0) {
606 vnlruproc_sig = 1; /* avoid unnecessary wakeups */
609 tsleep(&vnlruproc_sig, 0, "vlruwk", hz);
615 struct thread *td = curthread;
618 EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, td,
623 kproc_suspend_loop();
626 * Try to free some vnodes if we have too many
628 if (numvnodes > desiredvnodes &&
629 freevnodes > desiredvnodes * 2 / 10) {
630 int count = numvnodes - desiredvnodes;
632 if (count > freevnodes / 100)
633 count = freevnodes / 100;
636 freesomevnodes(count);
640 * Nothing to do if most of our vnodes are already on
643 if (numvnodes - freevnodes <= desiredvnodes * 9 / 10) {
645 wakeup(&vnlruproc_sig);
646 tsleep(td, 0, "vlruwt", hz);
650 done = mountlist_scan(vlrureclaim, NULL, MNTSCAN_FORWARD);
653 * The vlrureclaim() call only processes 1/10 of the vnodes
654 * on each mount. If we couldn't find any repeat the loop
655 * at least enough times to cover all available vnodes before
656 * we start sleeping. Complain if the failure extends past
657 * 30 second, every 30 seconds.
661 if (vnlru_nowhere % 10 == 0)
662 tsleep(td, 0, "vlrup", hz * 3);
663 if (vnlru_nowhere % 100 == 0)
664 kprintf("vnlru_proc: vnode recycler stopped working!\n");
665 if (vnlru_nowhere == 1000)
675 * MOUNTLIST FUNCTIONS
679 * mountlist_insert (MP SAFE)
681 * Add a new mount point to the mount list.
684 mountlist_insert(struct mount *mp, int how)
688 lwkt_gettoken(&ilock, &mountlist_token);
689 if (how == MNTINS_FIRST)
690 TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
692 TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
693 lwkt_reltoken(&ilock);
697 * mountlist_interlock (MP SAFE)
699 * Execute the specified interlock function with the mountlist token
700 * held. The function will be called in a serialized fashion verses
701 * other functions called through this mechanism.
704 mountlist_interlock(int (*callback)(struct mount *), struct mount *mp)
709 lwkt_gettoken(&ilock, &mountlist_token);
710 error = callback(mp);
711 lwkt_reltoken(&ilock);
716 * mountlist_boot_getfirst (DURING BOOT ONLY)
718 * This function returns the first mount on the mountlist, which is
719 * expected to be the root mount. Since no interlocks are obtained
720 * this function is only safe to use during booting.
724 mountlist_boot_getfirst(void)
726 return(TAILQ_FIRST(&mountlist));
730 * mountlist_remove (MP SAFE)
732 * Remove a node from the mountlist. If this node is the next scan node
733 * for any active mountlist scans, the active mountlist scan will be
734 * adjusted to skip the node, thus allowing removals during mountlist
738 mountlist_remove(struct mount *mp)
740 struct mountscan_info *msi;
743 lwkt_gettoken(&ilock, &mountlist_token);
744 TAILQ_FOREACH(msi, &mountscan_list, msi_entry) {
745 if (msi->msi_node == mp) {
746 if (msi->msi_how & MNTSCAN_FORWARD)
747 msi->msi_node = TAILQ_NEXT(mp, mnt_list);
749 msi->msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
752 TAILQ_REMOVE(&mountlist, mp, mnt_list);
753 lwkt_reltoken(&ilock);
757 * mountlist_scan (MP SAFE)
759 * Safely scan the mount points on the mount list. Unless otherwise
760 * specified each mount point will be busied prior to the callback and
761 * unbusied afterwords. The callback may safely remove any mount point
762 * without interfering with the scan. If the current callback
763 * mount is removed the scanner will not attempt to unbusy it.
765 * If a mount node cannot be busied it is silently skipped.
767 * The callback return value is aggregated and a total is returned. A return
768 * value of < 0 is not aggregated and will terminate the scan.
770 * MNTSCAN_FORWARD - the mountlist is scanned in the forward direction
771 * MNTSCAN_REVERSE - the mountlist is scanned in reverse
772 * MNTSCAN_NOBUSY - the scanner will make the callback without busying
776 mountlist_scan(int (*callback)(struct mount *, void *), void *data, int how)
778 struct mountscan_info info;
785 lwkt_gettoken(&ilock, &mountlist_token);
788 info.msi_node = NULL; /* paranoia */
789 TAILQ_INSERT_TAIL(&mountscan_list, &info, msi_entry);
794 if (how & MNTSCAN_FORWARD) {
795 info.msi_node = TAILQ_FIRST(&mountlist);
796 while ((mp = info.msi_node) != NULL) {
797 if (how & MNTSCAN_NOBUSY) {
798 count = callback(mp, data);
799 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
800 count = callback(mp, data);
801 if (mp == info.msi_node)
809 if (mp == info.msi_node)
810 info.msi_node = TAILQ_NEXT(mp, mnt_list);
812 } else if (how & MNTSCAN_REVERSE) {
813 info.msi_node = TAILQ_LAST(&mountlist, mntlist);
814 while ((mp = info.msi_node) != NULL) {
815 if (how & MNTSCAN_NOBUSY) {
816 count = callback(mp, data);
817 } else if (vfs_busy(mp, LK_NOWAIT) == 0) {
818 count = callback(mp, data);
819 if (mp == info.msi_node)
827 if (mp == info.msi_node)
828 info.msi_node = TAILQ_PREV(mp, mntlist, mnt_list);
831 TAILQ_REMOVE(&mountscan_list, &info, msi_entry);
832 lwkt_reltoken(&ilock);
837 * MOUNT RELATED VNODE FUNCTIONS
840 static struct kproc_desc vnlru_kp = {
845 SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp)
848 * Move a vnode from one mount queue to another.
851 insmntque(struct vnode *vp, struct mount *mp)
855 lwkt_gettoken(&ilock, &mntvnode_token);
857 * Delete from old mount point vnode list, if on one.
859 if (vp->v_mount != NULL) {
860 KASSERT(vp->v_mount->mnt_nvnodelistsize > 0,
861 ("bad mount point vnode list size"));
863 vp->v_mount->mnt_nvnodelistsize--;
866 * Insert into list of vnodes for the new mount point, if available.
867 * The 'end' of the LRU list is the vnode prior to mp->mnt_syncer.
869 if ((vp->v_mount = mp) == NULL) {
870 lwkt_reltoken(&ilock);
873 if (mp->mnt_syncer) {
874 TAILQ_INSERT_BEFORE(mp->mnt_syncer, vp, v_nmntvnodes);
876 TAILQ_INSERT_TAIL(&mp->mnt_nvnodelist, vp, v_nmntvnodes);
878 mp->mnt_nvnodelistsize++;
879 lwkt_reltoken(&ilock);
884 * Scan the vnodes under a mount point and issue appropriate callbacks.
886 * The fastfunc() callback is called with just the mountlist token held
887 * (no vnode lock). It may not block and the vnode may be undergoing
888 * modifications while the caller is processing it. The vnode will
889 * not be entirely destroyed, however, due to the fact that the mountlist
890 * token is held. A return value < 0 skips to the next vnode without calling
891 * the slowfunc(), a return value > 0 terminates the loop.
893 * The slowfunc() callback is called after the vnode has been successfully
894 * locked based on passed flags. The vnode is skipped if it gets rearranged
895 * or destroyed while blocking on the lock. A non-zero return value from
896 * the slow function terminates the loop. The slow function is allowed to
897 * arbitrarily block. The scanning code guarentees consistency of operation
898 * even if the slow function deletes or moves the node, or blocks and some
899 * other thread deletes or moves the node.
905 int (*fastfunc)(struct mount *mp, struct vnode *vp, void *data),
906 int (*slowfunc)(struct mount *mp, struct vnode *vp, void *data),
909 struct vmntvnodescan_info info;
913 int maxcount = 1000000;
917 lwkt_gettoken(&ilock, &mntvnode_token);
920 * If asked to do one pass stop after iterating available vnodes.
921 * Under heavy loads new vnodes can be added while we are scanning,
922 * so this isn't perfect. Create a slop factor of 2x.
924 if (flags & VMSC_ONEPASS)
925 stopcount = mp->mnt_nvnodelistsize * 2;
927 info.vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
928 TAILQ_INSERT_TAIL(&mntvnodescan_list, &info, entry);
929 while ((vp = info.vp) != NULL) {
931 panic("maxcount reached during vmntvnodescan");
934 * Skip if visible but not ready, or special (e.g.
937 if (vp->v_type == VNON)
939 KKASSERT(vp->v_mount == mp);
942 * Quick test. A negative return continues the loop without
943 * calling the slow test. 0 continues onto the slow test.
944 * A positive number aborts the loop.
947 if ((r = fastfunc(mp, vp, data)) < 0)
954 * Get a vxlock on the vnode, retry if it has moved or isn't
955 * in the mountlist where we expect it.
960 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) {
962 error = vget(vp, LK_EXCLUSIVE);
964 case VMSC_GETVP|VMSC_NOWAIT:
965 error = vget(vp, LK_EXCLUSIVE|LK_NOWAIT);
978 * Do not call the slow function if the vnode is
979 * invalid or if it was ripped out from under us
980 * while we (potentially) blocked.
982 if (info.vp == vp && vp->v_type != VNON)
983 r = slowfunc(mp, vp, data);
988 switch(flags & (VMSC_GETVP|VMSC_GETVX|VMSC_NOWAIT)) {
990 case VMSC_GETVP|VMSC_NOWAIT:
1005 * Yield after some processing. Depending on the number
1006 * of vnodes, we might wind up running for a long time.
1007 * Because threads are not preemptable, time critical
1008 * userland processes might starve. Give them a chance
1011 if (++count == 10000) {
1012 /* We really want to yield a bit, so we simply sleep a tick */
1013 tsleep(mp, 0, "vnodescn", 1);
1018 * If doing one pass this decrements to zero. If it starts
1019 * at zero it is effectively unlimited for the purposes of
1022 if (--stopcount == 0)
1026 * Iterate. If the vnode was ripped out from under us
1027 * info.vp will already point to the next vnode, otherwise
1028 * we have to obtain the next valid vnode ourselves.
1031 info.vp = TAILQ_NEXT(vp, v_nmntvnodes);
1033 TAILQ_REMOVE(&mntvnodescan_list, &info, entry);
1034 lwkt_reltoken(&ilock);
1039 * Remove any vnodes in the vnode table belonging to mount point mp.
1041 * If FORCECLOSE is not specified, there should not be any active ones,
1042 * return error if any are found (nb: this is a user error, not a
1043 * system error). If FORCECLOSE is specified, detach any active vnodes
1046 * If WRITECLOSE is set, only flush out regular file vnodes open for
1049 * SKIPSYSTEM causes any vnodes marked VSYSTEM to be skipped.
1051 * `rootrefs' specifies the base reference count for the root vnode
1052 * of this filesystem. The root vnode is considered busy if its
1053 * v_sysref.refcnt exceeds this value. On a successful return, vflush()
1054 * will call vrele() on the root vnode exactly rootrefs times.
1055 * If the SKIPSYSTEM or WRITECLOSE flags are specified, rootrefs must
1059 static int busyprt = 0; /* print out busy vnodes */
1060 SYSCTL_INT(_debug, OID_AUTO, busyprt, CTLFLAG_RW, &busyprt, 0, "");
1063 static int vflush_scan(struct mount *mp, struct vnode *vp, void *data);
1065 struct vflush_info {
1072 vflush(struct mount *mp, int rootrefs, int flags)
1074 struct thread *td = curthread; /* XXX */
1075 struct vnode *rootvp = NULL;
1077 struct vflush_info vflush_info;
1080 KASSERT((flags & (SKIPSYSTEM | WRITECLOSE)) == 0,
1081 ("vflush: bad args"));
1083 * Get the filesystem root vnode. We can vput() it
1084 * immediately, since with rootrefs > 0, it won't go away.
1086 if ((error = VFS_ROOT(mp, &rootvp)) != 0)
1091 vflush_info.busy = 0;
1092 vflush_info.flags = flags;
1093 vflush_info.td = td;
1094 vmntvnodescan(mp, VMSC_GETVX, NULL, vflush_scan, &vflush_info);
1096 if (rootrefs > 0 && (flags & FORCECLOSE) == 0) {
1098 * If just the root vnode is busy, and if its refcount
1099 * is equal to `rootrefs', then go ahead and kill it.
1101 KASSERT(vflush_info.busy > 0, ("vflush: not busy"));
1102 KASSERT(rootvp->v_sysref.refcnt >= rootrefs, ("vflush: rootrefs"));
1103 if (vflush_info.busy == 1 && rootvp->v_sysref.refcnt == rootrefs) {
1105 vgone_vxlocked(rootvp);
1107 vflush_info.busy = 0;
1110 if (vflush_info.busy)
1112 for (; rootrefs > 0; rootrefs--)
1118 * The scan callback is made with an VX locked vnode.
1121 vflush_scan(struct mount *mp, struct vnode *vp, void *data)
1123 struct vflush_info *info = data;
1127 * Skip over a vnodes marked VSYSTEM.
1129 if ((info->flags & SKIPSYSTEM) && (vp->v_flag & VSYSTEM)) {
1134 * If WRITECLOSE is set, flush out unlinked but still open
1135 * files (even if open only for reading) and regular file
1136 * vnodes open for writing.
1138 if ((info->flags & WRITECLOSE) &&
1139 (vp->v_type == VNON ||
1140 (VOP_GETATTR(vp, &vattr) == 0 &&
1141 vattr.va_nlink > 0)) &&
1142 (vp->v_writecount == 0 || vp->v_type != VREG)) {
1147 * If we are the only holder (refcnt of 1) or the vnode is in
1148 * termination (refcnt < 0), we can vgone the vnode.
1150 if (vp->v_sysref.refcnt <= 1) {
1156 * If FORCECLOSE is set, forcibly close the vnode. For block
1157 * or character devices, revert to an anonymous device. For
1158 * all other files, just kill them.
1160 if (info->flags & FORCECLOSE) {
1161 if (vp->v_type != VBLK && vp->v_type != VCHR) {
1164 vclean_vxlocked(vp, 0);
1165 vp->v_ops = &spec_vnode_vops_p;
1166 insmntque(vp, NULL);
1172 vprint("vflush: busy vnode", vp);
1179 add_bio_ops(struct bio_ops *ops)
1181 TAILQ_INSERT_TAIL(&bio_ops_list, ops, entry);
1185 rem_bio_ops(struct bio_ops *ops)
1187 TAILQ_REMOVE(&bio_ops_list, ops, entry);
1191 * This calls the bio_ops io_sync function either for a mount point
1194 * WARNING: softdeps is weirdly coded and just isn't happy unless
1195 * io_sync is called with a NULL mount from the general syncing code.
1198 bio_ops_sync(struct mount *mp)
1200 struct bio_ops *ops;
1203 if ((ops = mp->mnt_bioops) != NULL)
1206 TAILQ_FOREACH(ops, &bio_ops_list, entry) {