2 * Copyright (c) 2003,2004 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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23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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34 * Copyright (c) 1989, 1993, 1995
35 * The Regents of the University of California. All rights reserved.
37 * This code is derived from software contributed to Berkeley by
38 * Poul-Henning Kamp of the FreeBSD Project.
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41 * modification, are permitted provided that the following conditions
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53 * may be used to endorse or promote products derived from this software
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61 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
62 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
63 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
64 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
65 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
68 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95
69 * $FreeBSD: src/sys/kern/vfs_cache.c,v 1.42.2.6 2001/10/05 20:07:03 dillon Exp $
70 * $DragonFly: src/sys/kern/vfs_cache.c,v 1.68 2006/05/24 03:23:31 dillon Exp $
73 #include <sys/param.h>
74 #include <sys/systm.h>
75 #include <sys/kernel.h>
76 #include <sys/sysctl.h>
77 #include <sys/mount.h>
78 #include <sys/vnode.h>
79 #include <sys/malloc.h>
80 #include <sys/sysproto.h>
82 #include <sys/namei.h>
83 #include <sys/nlookup.h>
84 #include <sys/filedesc.h>
85 #include <sys/fnv_hash.h>
86 #include <sys/globaldata.h>
87 #include <sys/kern_syscall.h>
88 #include <sys/dirent.h>
92 * Random lookups in the cache are accomplished with a hash table using
93 * a hash key of (nc_src_vp, name).
95 * Negative entries may exist and correspond to structures where nc_vp
96 * is NULL. In a negative entry, NCF_WHITEOUT will be set if the entry
97 * corresponds to a whited-out directory entry (verses simply not finding the
100 * Upon reaching the last segment of a path, if the reference is for DELETE,
101 * or NOCACHE is set (rewrite), and the name is located in the cache, it
106 * Structures associated with name cacheing.
108 #define NCHHASH(hash) (&nchashtbl[(hash) & nchash])
111 MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries");
113 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */
114 static struct namecache_list ncneglist; /* instead of vnode */
117 * ncvp_debug - debug cache_fromvp(). This is used by the NFS server
118 * to create the namecache infrastructure leading to a dangling vnode.
120 * 0 Only errors are reported
121 * 1 Successes are reported
122 * 2 Successes + the whole directory scan is reported
123 * 3 Force the directory scan code run as if the parent vnode did not
124 * have a namecache record, even if it does have one.
126 static int ncvp_debug;
127 SYSCTL_INT(_debug, OID_AUTO, ncvp_debug, CTLFLAG_RW, &ncvp_debug, 0, "");
129 static u_long nchash; /* size of hash table */
130 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, "");
132 static u_long ncnegfactor = 16; /* ratio of negative entries */
133 SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, "");
135 static int nclockwarn; /* warn on locked entries in ticks */
136 SYSCTL_INT(_debug, OID_AUTO, nclockwarn, CTLFLAG_RW, &nclockwarn, 0, "");
138 static u_long numneg; /* number of cache entries allocated */
139 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, "");
141 static u_long numcache; /* number of cache entries allocated */
142 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, "");
144 static u_long numunres; /* number of unresolved entries */
145 SYSCTL_ULONG(_debug, OID_AUTO, numunres, CTLFLAG_RD, &numunres, 0, "");
147 SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), "");
148 SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), "");
150 static int cache_resolve_mp(struct namecache *ncp);
151 static void cache_rehash(struct namecache *ncp);
154 * The new name cache statistics
156 SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics");
157 #define STATNODE(mode, name, var) \
158 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, "");
159 STATNODE(CTLFLAG_RD, numneg, &numneg);
160 STATNODE(CTLFLAG_RD, numcache, &numcache);
161 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls);
162 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits);
163 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits);
164 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks);
165 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss);
166 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap);
167 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps);
168 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits);
169 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps);
170 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits);
172 struct nchstats nchstats[SMP_MAXCPU];
174 * Export VFS cache effectiveness statistics to user-land.
176 * The statistics are left for aggregation to user-land so
177 * neat things can be achieved, like observing per-CPU cache
181 sysctl_nchstats(SYSCTL_HANDLER_ARGS)
183 struct globaldata *gd;
187 for (i = 0; i < ncpus; ++i) {
188 gd = globaldata_find(i);
189 if ((error = SYSCTL_OUT(req, (void *)&(*gd->gd_nchstats),
190 sizeof(struct nchstats))))
196 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE|CTLFLAG_RD,
197 0, 0, sysctl_nchstats, "S,nchstats", "VFS cache effectiveness statistics");
199 static void cache_zap(struct namecache *ncp);
202 * cache_hold() and cache_drop() prevent the premature deletion of a
203 * namecache entry but do not prevent operations (such as zapping) on
204 * that namecache entry.
206 * This routine may only be called if nc_refs is already at least 1.
208 * This is a rare case where callers are allowed to hold spinlocks, so
209 * we can't ourselves.
213 _cache_hold(struct namecache *ncp)
215 atomic_add_int(&ncp->nc_refs, 1);
220 * When dropping an entry, if only one ref remains and the entry has not
221 * been resolved, zap it. Since the one reference is being dropped the
222 * entry had better not be locked.
226 _cache_drop(struct namecache *ncp)
228 KKASSERT(ncp->nc_refs > 0);
229 if (ncp->nc_refs == 1 &&
230 (ncp->nc_flag & NCF_UNRESOLVED) &&
231 TAILQ_EMPTY(&ncp->nc_list)
233 KKASSERT(ncp->nc_exlocks == 0);
242 * Link a new namecache entry to its parent. Be careful to avoid races
243 * if vhold() blocks in the future.
245 * If we are creating a child under an oldapi parent we must mark the
246 * child as being an oldapi entry as well.
249 cache_link_parent(struct namecache *ncp, struct namecache *par)
251 KKASSERT(ncp->nc_parent == NULL);
252 ncp->nc_parent = par;
253 if (TAILQ_EMPTY(&par->nc_list)) {
254 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry);
256 * Any vp associated with an ncp which has children must
257 * be held to prevent it from being recycled.
262 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry);
267 * Remove the parent association from a namecache structure. If this is
268 * the last child of the parent the cache_drop(par) will attempt to
269 * recursively zap the parent.
272 cache_unlink_parent(struct namecache *ncp)
274 struct namecache *par;
276 if ((par = ncp->nc_parent) != NULL) {
277 ncp->nc_parent = NULL;
278 par = cache_hold(par);
279 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry);
280 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list))
287 * Allocate a new namecache structure. Most of the code does not require
288 * zero-termination of the string but it makes vop_compat_ncreate() easier.
290 static struct namecache *
291 cache_alloc(int nlen)
293 struct namecache *ncp;
295 ncp = malloc(sizeof(*ncp), M_VFSCACHE, M_WAITOK|M_ZERO);
297 ncp->nc_name = malloc(nlen + 1, M_VFSCACHE, M_WAITOK);
299 ncp->nc_flag = NCF_UNRESOLVED;
300 ncp->nc_error = ENOTCONN; /* needs to be resolved */
304 * Construct a fake FSMID based on the time of day and a 32 bit
305 * roller for uniqueness. This is used to generate a useful
306 * FSMID for filesystems which do not support it.
308 ncp->nc_fsmid = cache_getnewfsmid();
309 TAILQ_INIT(&ncp->nc_list);
315 cache_free(struct namecache *ncp)
317 KKASSERT(ncp->nc_refs == 1 && ncp->nc_exlocks == 1);
319 free(ncp->nc_name, M_VFSCACHE);
320 free(ncp, M_VFSCACHE);
324 * Ref and deref a namecache structure.
326 * Warning: caller may hold an unrelated read spinlock, which means we can't
327 * use read spinlocks here.
330 cache_hold(struct namecache *ncp)
332 return(_cache_hold(ncp));
336 cache_drop(struct namecache *ncp)
342 * Namespace locking. The caller must already hold a reference to the
343 * namecache structure in order to lock/unlock it. This function prevents
344 * the namespace from being created or destroyed by accessors other then
347 * Note that holding a locked namecache structure prevents other threads
348 * from making namespace changes (e.g. deleting or creating), prevents
349 * vnode association state changes by other threads, and prevents the
350 * namecache entry from being resolved or unresolved by other threads.
352 * The lock owner has full authority to associate/disassociate vnodes
353 * and resolve/unresolve the locked ncp.
355 * WARNING! Holding a locked ncp will prevent a vnode from being destroyed
356 * or recycled, but it does NOT help you if the vnode had already initiated
357 * a recyclement. If this is important, use cache_get() rather then
358 * cache_lock() (and deal with the differences in the way the refs counter
359 * is handled). Or, alternatively, make an unconditional call to
360 * cache_validate() or cache_resolve() after cache_lock() returns.
363 cache_lock(struct namecache *ncp)
368 KKASSERT(ncp->nc_refs != 0);
373 if (ncp->nc_exlocks == 0) {
377 * The vp associated with a locked ncp must be held
378 * to prevent it from being recycled (which would
379 * cause the ncp to become unresolved).
381 * WARNING! If VRECLAIMED is set the vnode could
382 * already be in the middle of a recycle. Callers
383 * should not assume that nc_vp is usable when
384 * not NULL. cache_vref() or cache_vget() must be
387 * XXX loop on race for later MPSAFE work.
393 if (ncp->nc_locktd == td) {
397 ncp->nc_flag |= NCF_LOCKREQ;
398 if (tsleep(ncp, 0, "clock", nclockwarn) == EWOULDBLOCK) {
402 printf("[diagnostic] cache_lock: blocked on %p", ncp);
403 if ((ncp->nc_flag & NCF_MOUNTPT) && ncp->nc_mount)
404 printf(" [MOUNTFROM %s]\n", ncp->nc_mount->mnt_stat.f_mntfromname);
406 printf(" \"%*.*s\"\n",
407 ncp->nc_nlen, ncp->nc_nlen,
413 printf("[diagnostic] cache_lock: unblocked %*.*s\n",
414 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name);
419 cache_lock_nonblock(struct namecache *ncp)
423 KKASSERT(ncp->nc_refs != 0);
425 if (ncp->nc_exlocks == 0) {
429 * The vp associated with a locked ncp must be held
430 * to prevent it from being recycled (which would
431 * cause the ncp to become unresolved).
433 * WARNING! If VRECLAIMED is set the vnode could
434 * already be in the middle of a recycle. Callers
435 * should not assume that nc_vp is usable when
436 * not NULL. cache_vref() or cache_vget() must be
439 * XXX loop on race for later MPSAFE work.
450 cache_unlock(struct namecache *ncp)
452 thread_t td = curthread;
454 KKASSERT(ncp->nc_refs > 0);
455 KKASSERT(ncp->nc_exlocks > 0);
456 KKASSERT(ncp->nc_locktd == td);
457 if (--ncp->nc_exlocks == 0) {
460 ncp->nc_locktd = NULL;
461 if (ncp->nc_flag & NCF_LOCKREQ) {
462 ncp->nc_flag &= ~NCF_LOCKREQ;
469 * ref-and-lock, unlock-and-deref functions.
471 * This function is primarily used by nlookup. Even though cache_lock
472 * holds the vnode, it is possible that the vnode may have already
473 * initiated a recyclement. We want cache_get() to return a definitively
474 * usable vnode or a definitively unresolved ncp.
477 cache_get(struct namecache *ncp)
481 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
482 cache_setunresolved(ncp);
487 cache_get_nonblock(struct namecache *ncp)
490 if (ncp->nc_exlocks == 0 || ncp->nc_locktd == curthread) {
493 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
494 cache_setunresolved(ncp);
501 cache_put(struct namecache *ncp)
508 * Resolve an unresolved ncp by associating a vnode with it. If the
509 * vnode is NULL, a negative cache entry is created.
511 * The ncp should be locked on entry and will remain locked on return.
514 cache_setvp(struct namecache *ncp, struct vnode *vp)
516 KKASSERT(ncp->nc_flag & NCF_UNRESOLVED);
520 * Any vp associated with an ncp which has children must
521 * be held. Any vp associated with a locked ncp must be held.
523 if (!TAILQ_EMPTY(&ncp->nc_list))
525 TAILQ_INSERT_HEAD(&vp->v_namecache, ncp, nc_vnode);
530 * Set auxillary flags
534 ncp->nc_flag |= NCF_ISDIR;
537 ncp->nc_flag |= NCF_ISSYMLINK;
538 /* XXX cache the contents of the symlink */
546 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode);
548 ncp->nc_error = ENOENT;
550 ncp->nc_flag &= ~NCF_UNRESOLVED;
554 cache_settimeout(struct namecache *ncp, int nticks)
556 if ((ncp->nc_timeout = ticks + nticks) == 0)
561 * Disassociate the vnode or negative-cache association and mark a
562 * namecache entry as unresolved again. Note that the ncp is still
563 * left in the hash table and still linked to its parent.
565 * The ncp should be locked and refd on entry and will remain locked and refd
568 * This routine is normally never called on a directory containing children.
569 * However, NFS often does just that in its rename() code as a cop-out to
570 * avoid complex namespace operations. This disconnects a directory vnode
571 * from its namecache and can cause the OLDAPI and NEWAPI to get out of
574 * NOTE: NCF_FSMID must be cleared so a refurbishment of the ncp, such as
575 * in a create, properly propogates flag up the chain.
578 cache_setunresolved(struct namecache *ncp)
582 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
583 ncp->nc_flag |= NCF_UNRESOLVED;
585 ncp->nc_error = ENOTCONN;
587 if ((vp = ncp->nc_vp) != NULL) {
590 TAILQ_REMOVE(&vp->v_namecache, ncp, nc_vnode);
593 * Any vp associated with an ncp with children is
594 * held by that ncp. Any vp associated with a locked
595 * ncp is held by that ncp. These conditions must be
596 * undone when the vp is cleared out from the ncp.
598 if (ncp->nc_flag & NCF_FSMID)
600 if (!TAILQ_EMPTY(&ncp->nc_list))
605 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode);
608 ncp->nc_flag &= ~(NCF_WHITEOUT|NCF_ISDIR|NCF_ISSYMLINK|
614 * Invalidate portions of the namecache topology given a starting entry.
615 * The passed ncp is set to an unresolved state and:
617 * The passed ncp must be locked.
619 * CINV_DESTROY - Set a flag in the passed ncp entry indicating
620 * that the physical underlying nodes have been
621 * destroyed... as in deleted. For example, when
622 * a directory is removed. This will cause record
623 * lookups on the name to no longer be able to find
624 * the record and tells the resolver to return failure
625 * rather then trying to resolve through the parent.
627 * The topology itself, including ncp->nc_name,
630 * This only applies to the passed ncp, if CINV_CHILDREN
631 * is specified the children are not flagged.
633 * CINV_CHILDREN - Set all children (recursively) to an unresolved
636 * Note that this will also have the side effect of
637 * cleaning out any unreferenced nodes in the topology
638 * from the leaves up as the recursion backs out.
640 * Note that the topology for any referenced nodes remains intact.
642 * It is possible for cache_inval() to race a cache_resolve(), meaning that
643 * the namecache entry may not actually be invalidated on return if it was
644 * revalidated while recursing down into its children. This code guarentees
645 * that the node(s) will go through an invalidation cycle, but does not
646 * guarentee that they will remain in an invalidated state.
648 * Returns non-zero if a revalidation was detected during the invalidation
649 * recursion, zero otherwise. Note that since only the original ncp is
650 * locked the revalidation ultimately can only indicate that the original ncp
651 * *MIGHT* no have been reresolved.
654 cache_inval(struct namecache *ncp, int flags)
656 struct namecache *kid;
657 struct namecache *nextkid;
660 KKASSERT(ncp->nc_exlocks);
662 cache_setunresolved(ncp);
663 if (flags & CINV_DESTROY)
664 ncp->nc_flag |= NCF_DESTROYED;
666 if ((flags & CINV_CHILDREN) &&
667 (kid = TAILQ_FIRST(&ncp->nc_list)) != NULL
672 if ((nextkid = TAILQ_NEXT(kid, nc_entry)) != NULL)
674 if ((kid->nc_flag & NCF_UNRESOLVED) == 0 ||
675 TAILQ_FIRST(&kid->nc_list)
678 rcnt += cache_inval(kid, flags & ~CINV_DESTROY);
688 * Someone could have gotten in there while ncp was unlocked,
691 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0)
697 * Invalidate a vnode's namecache associations. To avoid races against
698 * the resolver we do not invalidate a node which we previously invalidated
699 * but which was then re-resolved while we were in the invalidation loop.
701 * Returns non-zero if any namecache entries remain after the invalidation
704 * NOTE: unlike the namecache topology which guarentees that ncp's will not
705 * be ripped out of the topology while held, the vnode's v_namecache list
706 * has no such restriction. NCP's can be ripped out of the list at virtually
707 * any time if not locked, even if held.
710 cache_inval_vp(struct vnode *vp, int flags)
712 struct namecache *ncp;
713 struct namecache *next;
716 ncp = TAILQ_FIRST(&vp->v_namecache);
720 /* loop entered with ncp held */
721 if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL)
724 if (ncp->nc_vp != vp) {
725 printf("Warning: cache_inval_vp: race-A detected on "
726 "%s\n", ncp->nc_name);
732 cache_inval(ncp, flags);
733 cache_put(ncp); /* also releases reference */
735 if (ncp && ncp->nc_vp != vp) {
736 printf("Warning: cache_inval_vp: race-B detected on "
737 "%s\n", ncp->nc_name);
742 return(TAILQ_FIRST(&vp->v_namecache) != NULL);
746 * The source ncp has been renamed to the target ncp. Both fncp and tncp
747 * must be locked. Both will be set to unresolved, any children of tncp
748 * will be disconnected (the prior contents of the target is assumed to be
749 * destroyed by the rename operation, e.g. renaming over an empty directory),
750 * and all children of fncp will be moved to tncp.
752 * XXX the disconnection could pose a problem, check code paths to make
753 * sure any code that blocks can handle the parent being changed out from
754 * under it. Maybe we should lock the children (watch out for deadlocks) ?
756 * After we return the caller has the option of calling cache_setvp() if
757 * the vnode of the new target ncp is known.
759 * Any process CD'd into any of the children will no longer be able to ".."
760 * back out. An rm -rf can cause this situation to occur.
763 cache_rename(struct namecache *fncp, struct namecache *tncp)
765 struct namecache *scan;
768 cache_setunresolved(fncp);
769 cache_setunresolved(tncp);
770 while (cache_inval(tncp, CINV_CHILDREN) != 0) {
771 if (didwarn++ % 10 == 0) {
772 printf("Warning: cache_rename: race during "
774 fncp->nc_name, tncp->nc_name);
776 tsleep(tncp, 0, "mvrace", hz / 10);
777 cache_setunresolved(tncp);
779 while ((scan = TAILQ_FIRST(&fncp->nc_list)) != NULL) {
781 cache_unlink_parent(scan);
782 cache_link_parent(scan, tncp);
783 if (scan->nc_flag & NCF_HASHED)
790 * vget the vnode associated with the namecache entry. Resolve the namecache
791 * entry if necessary and deal with namecache/vp races. The passed ncp must
792 * be referenced and may be locked. The ncp's ref/locking state is not
793 * effected by this call.
795 * lk_type may be LK_SHARED, LK_EXCLUSIVE. A ref'd, possibly locked
796 * (depending on the passed lk_type) will be returned in *vpp with an error
797 * of 0, or NULL will be returned in *vpp with a non-0 error code. The
798 * most typical error is ENOENT, meaning that the ncp represents a negative
799 * cache hit and there is no vnode to retrieve, but other errors can occur
802 * The main race we have to deal with are namecache zaps. The ncp itself
803 * will not disappear since it is referenced, and it turns out that the
804 * validity of the vp pointer can be checked simply by rechecking the
805 * contents of ncp->nc_vp.
808 cache_vget(struct namecache *ncp, struct ucred *cred,
809 int lk_type, struct vnode **vpp)
816 if (ncp->nc_flag & NCF_UNRESOLVED) {
818 error = cache_resolve(ncp, cred);
823 if (error == 0 && (vp = ncp->nc_vp) != NULL) {
825 * Accessing the vnode from the namecache is a bit
826 * dangerous. Because there are no refs on the vnode, it
827 * could be in the middle of a reclaim.
829 if (vp->v_flag & VRECLAIMED) {
830 printf("Warning: vnode reclaim race detected in cache_vget on %p (%s)\n", vp, ncp->nc_name);
832 cache_setunresolved(ncp);
836 error = vget(vp, lk_type);
838 if (vp != ncp->nc_vp)
841 } else if (vp != ncp->nc_vp) {
844 } else if (vp->v_flag & VRECLAIMED) {
845 panic("vget succeeded on a VRECLAIMED node! vp %p", vp);
848 if (error == 0 && vp == NULL)
855 cache_vref(struct namecache *ncp, struct ucred *cred, struct vnode **vpp)
862 if (ncp->nc_flag & NCF_UNRESOLVED) {
864 error = cache_resolve(ncp, cred);
869 if (error == 0 && (vp = ncp->nc_vp) != NULL) {
871 * Since we did not obtain any locks, a cache zap
872 * race can occur here if the vnode is in the middle
873 * of being reclaimed and has not yet been able to
874 * clean out its cache node. If that case occurs,
875 * we must lock and unresolve the cache, then loop
878 if (vp->v_flag & VRECLAIMED) {
879 printf("Warning: vnode reclaim race detected on cache_vref %p (%s)\n", vp, ncp->nc_name);
881 cache_setunresolved(ncp);
887 if (error == 0 && vp == NULL)
894 * Recursively set the FSMID update flag for namecache nodes leading
895 * to root. This will cause the next getattr or reclaim to increment the
896 * fsmid and mark the inode for lazy updating.
898 * Stop recursing when we hit a node whos NCF_FSMID flag is already set.
899 * This makes FSMIDs work in an Einsteinian fashion - where the observation
900 * effects the result. In this case a program monitoring a higher level
901 * node will have detected some prior change and started its scan (clearing
902 * NCF_FSMID in higher level nodes), but since it has not yet observed the
903 * node where we find NCF_FSMID still set, we can safely make the related
904 * modification without interfering with the theorized program.
906 * This also means that FSMIDs cannot represent time-domain quantities
907 * in a hierarchical sense. But the main reason for doing it this way
908 * is to reduce the amount of recursion that occurs in the critical path
909 * when e.g. a program is writing to a file that sits deep in a directory
913 cache_update_fsmid(struct namecache *ncp)
916 struct namecache *scan;
919 * Warning: even if we get a non-NULL vp it could still be in the
920 * middle of a recyclement. Don't do anything fancy, just set
923 if ((vp = ncp->nc_vp) != NULL) {
924 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
925 for (scan = ncp; scan; scan = scan->nc_parent) {
926 if (scan->nc_flag & NCF_FSMID)
928 scan->nc_flag |= NCF_FSMID;
932 while (ncp && (ncp->nc_flag & NCF_FSMID) == 0) {
933 ncp->nc_flag |= NCF_FSMID;
934 ncp = ncp->nc_parent;
940 cache_update_fsmid_vp(struct vnode *vp)
942 struct namecache *ncp;
943 struct namecache *scan;
945 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
946 for (scan = ncp; scan; scan = scan->nc_parent) {
947 if (scan->nc_flag & NCF_FSMID)
949 scan->nc_flag |= NCF_FSMID;
955 * If getattr is called on a vnode (e.g. a stat call), the filesystem
956 * may call this routine to determine if the namecache has the hierarchical
957 * change flag set, requiring the fsmid to be updated.
959 * Since 0 indicates no support, make sure the filesystem fsmid is at least
963 cache_check_fsmid_vp(struct vnode *vp, int64_t *fsmid)
965 struct namecache *ncp;
968 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
969 if (ncp->nc_flag & NCF_FSMID) {
970 ncp->nc_flag &= ~NCF_FSMID;
982 * Convert a directory vnode to a namecache record without any other
983 * knowledge of the topology. This ONLY works with directory vnodes and
984 * is ONLY used by the NFS server. dvp must be refd but unlocked, and the
985 * returned ncp (if not NULL) will be held and unlocked.
987 * If 'makeit' is 0 and dvp has no existing namecache record, NULL is returned.
988 * If 'makeit' is 1 we attempt to track-down and create the namecache topology
989 * for dvp. This will fail only if the directory has been deleted out from
992 * Callers must always check for a NULL return no matter the value of 'makeit'.
994 * To avoid underflowing the kernel stack each recursive call increments
995 * the makeit variable.
998 static int cache_inefficient_scan(struct namecache *ncp, struct ucred *cred,
1000 static int cache_fromdvp_try(struct vnode *dvp, struct ucred *cred,
1001 struct vnode **saved_dvp);
1004 cache_fromdvp(struct vnode *dvp, struct ucred *cred, int makeit)
1006 struct namecache *ncp;
1007 struct vnode *saved_dvp;
1015 * Temporary debugging code to force the directory scanning code
1018 if (ncvp_debug >= 3 && makeit && TAILQ_FIRST(&dvp->v_namecache)) {
1019 ncp = TAILQ_FIRST(&dvp->v_namecache);
1020 printf("cache_fromdvp: forcing %s\n", ncp->nc_name);
1025 * Loop until resolution, inside code will break out on error.
1027 while ((ncp = TAILQ_FIRST(&dvp->v_namecache)) == NULL && makeit) {
1030 * If dvp is the root of its filesystem it should already
1031 * have a namecache pointer associated with it as a side
1032 * effect of the mount, but it may have been disassociated.
1034 if (dvp->v_flag & VROOT) {
1035 ncp = cache_get(dvp->v_mount->mnt_ncp);
1036 error = cache_resolve_mp(ncp);
1039 printf("cache_fromdvp: resolve root of mount %p error %d",
1040 dvp->v_mount, error);
1044 printf(" failed\n");
1049 printf(" succeeded\n");
1054 * If we are recursed too deeply resort to an O(n^2)
1055 * algorithm to resolve the namecache topology. The
1056 * resolved pvp is left referenced in saved_dvp to
1057 * prevent the tree from being destroyed while we loop.
1060 error = cache_fromdvp_try(dvp, cred, &saved_dvp);
1062 printf("lookupdotdot(longpath) failed %d "
1063 "dvp %p\n", error, dvp);
1070 * Get the parent directory and resolve its ncp.
1072 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred);
1074 printf("lookupdotdot failed %d dvp %p\n", error, dvp);
1080 * Reuse makeit as a recursion depth counter.
1082 ncp = cache_fromdvp(pvp, cred, makeit + 1);
1088 * Do an inefficient scan of pvp (embodied by ncp) to look
1089 * for dvp. This will create a namecache record for dvp on
1090 * success. We loop up to recheck on success.
1092 * ncp and dvp are both held but not locked.
1094 error = cache_inefficient_scan(ncp, cred, dvp);
1097 printf("cache_fromdvp: scan %p (%s) failed on dvp=%p\n",
1098 pvp, ncp->nc_name, dvp);
1103 printf("cache_fromdvp: scan %p (%s) succeeded\n",
1115 * Go up the chain of parent directories until we find something
1116 * we can resolve into the namecache. This is very inefficient.
1120 cache_fromdvp_try(struct vnode *dvp, struct ucred *cred,
1121 struct vnode **saved_dvp)
1123 struct namecache *ncp;
1126 static time_t last_fromdvp_report;
1129 * Loop getting the parent directory vnode until we get something we
1130 * can resolve in the namecache.
1134 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred);
1140 if ((ncp = TAILQ_FIRST(&pvp->v_namecache)) != NULL) {
1145 if (pvp->v_flag & VROOT) {
1146 ncp = cache_get(pvp->v_mount->mnt_ncp);
1147 error = cache_resolve_mp(ncp);
1160 if (last_fromdvp_report != time_second) {
1161 last_fromdvp_report = time_second;
1162 printf("Warning: extremely inefficient path resolution on %s\n",
1165 error = cache_inefficient_scan(ncp, cred, dvp);
1168 * Hopefully dvp now has a namecache record associated with it.
1169 * Leave it referenced to prevent the kernel from recycling the
1170 * vnode. Otherwise extremely long directory paths could result
1171 * in endless recycling.
1181 * Do an inefficient scan of the directory represented by ncp looking for
1182 * the directory vnode dvp. ncp must be held but not locked on entry and
1183 * will be held on return. dvp must be refd but not locked on entry and
1184 * will remain refd on return.
1186 * Why do this at all? Well, due to its stateless nature the NFS server
1187 * converts file handles directly to vnodes without necessarily going through
1188 * the namecache ops that would otherwise create the namecache topology
1189 * leading to the vnode. We could either (1) Change the namecache algorithms
1190 * to allow disconnect namecache records that are re-merged opportunistically,
1191 * or (2) Make the NFS server backtrack and scan to recover a connected
1192 * namecache topology in order to then be able to issue new API lookups.
1194 * It turns out that (1) is a huge mess. It takes a nice clean set of
1195 * namecache algorithms and introduces a lot of complication in every subsystem
1196 * that calls into the namecache to deal with the re-merge case, especially
1197 * since we are using the namecache to placehold negative lookups and the
1198 * vnode might not be immediately assigned. (2) is certainly far less
1199 * efficient then (1), but since we are only talking about directories here
1200 * (which are likely to remain cached), the case does not actually run all
1201 * that often and has the supreme advantage of not polluting the namecache
1205 cache_inefficient_scan(struct namecache *ncp, struct ucred *cred,
1208 struct nlcomponent nlc;
1209 struct namecache *rncp;
1221 vat.va_blocksize = 0;
1222 if ((error = VOP_GETATTR(dvp, &vat)) != 0)
1224 if ((error = cache_vget(ncp, cred, LK_SHARED, &pvp)) != 0)
1227 printf("inefficient_scan: directory iosize %ld vattr fileid = %ld\n", vat.va_blocksize, (long)vat.va_fileid);
1228 if ((blksize = vat.va_blocksize) == 0)
1229 blksize = DEV_BSIZE;
1230 rbuf = malloc(blksize, M_TEMP, M_WAITOK);
1236 iov.iov_base = rbuf;
1237 iov.iov_len = blksize;
1240 uio.uio_resid = blksize;
1241 uio.uio_segflg = UIO_SYSSPACE;
1242 uio.uio_rw = UIO_READ;
1243 uio.uio_td = curthread;
1245 if (ncvp_debug >= 2)
1246 printf("cache_inefficient_scan: readdir @ %08x\n", (int)uio.uio_offset);
1247 error = VOP_READDIR(pvp, &uio, cred, &eofflag, NULL, NULL);
1249 den = (struct dirent *)rbuf;
1250 bytes = blksize - uio.uio_resid;
1253 if (ncvp_debug >= 2) {
1254 printf("cache_inefficient_scan: %*.*s\n",
1255 den->d_namlen, den->d_namlen,
1258 if (den->d_type != DT_WHT &&
1259 den->d_ino == vat.va_fileid) {
1261 printf("cache_inefficient_scan: "
1262 "MATCHED inode %ld path %s/%*.*s\n",
1263 vat.va_fileid, ncp->nc_name,
1264 den->d_namlen, den->d_namlen,
1267 nlc.nlc_nameptr = den->d_name;
1268 nlc.nlc_namelen = den->d_namlen;
1270 rncp = cache_nlookup(ncp, &nlc);
1271 KKASSERT(rncp != NULL);
1274 bytes -= _DIRENT_DIRSIZ(den);
1275 den = _DIRENT_NEXT(den);
1277 if (rncp == NULL && eofflag == 0 && uio.uio_resid != blksize)
1282 if (rncp->nc_flag & NCF_UNRESOLVED) {
1283 cache_setvp(rncp, dvp);
1284 if (ncvp_debug >= 2) {
1285 printf("cache_inefficient_scan: setvp %s/%s = %p\n",
1286 ncp->nc_name, rncp->nc_name, dvp);
1289 if (ncvp_debug >= 2) {
1290 printf("cache_inefficient_scan: setvp %s/%s already set %p/%p\n",
1291 ncp->nc_name, rncp->nc_name, dvp,
1295 if (rncp->nc_vp == NULL)
1296 error = rncp->nc_error;
1299 printf("cache_inefficient_scan: dvp %p NOT FOUND in %s\n",
1309 * Zap a namecache entry. The ncp is unconditionally set to an unresolved
1310 * state, which disassociates it from its vnode or ncneglist.
1312 * Then, if there are no additional references to the ncp and no children,
1313 * the ncp is removed from the topology and destroyed. This function will
1314 * also run through the nc_parent chain and destroy parent ncps if possible.
1315 * As a side benefit, it turns out the only conditions that allow running
1316 * up the chain are also the conditions to ensure no deadlock will occur.
1318 * References and/or children may exist if the ncp is in the middle of the
1319 * topology, preventing the ncp from being destroyed.
1321 * This function must be called with the ncp held and locked and will unlock
1322 * and drop it during zapping.
1325 cache_zap(struct namecache *ncp)
1327 struct namecache *par;
1330 * Disassociate the vnode or negative cache ref and set NCF_UNRESOLVED.
1332 cache_setunresolved(ncp);
1335 * Try to scrap the entry and possibly tail-recurse on its parent.
1336 * We only scrap unref'd (other then our ref) unresolved entries,
1337 * we do not scrap 'live' entries.
1339 while (ncp->nc_flag & NCF_UNRESOLVED) {
1341 * Someone other then us has a ref, stop.
1343 if (ncp->nc_refs > 1)
1347 * We have children, stop.
1349 if (!TAILQ_EMPTY(&ncp->nc_list))
1353 * Remove ncp from the topology: hash table and parent linkage.
1355 if (ncp->nc_flag & NCF_HASHED) {
1356 ncp->nc_flag &= ~NCF_HASHED;
1357 LIST_REMOVE(ncp, nc_hash);
1359 if ((par = ncp->nc_parent) != NULL) {
1360 par = cache_hold(par);
1361 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry);
1362 ncp->nc_parent = NULL;
1363 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list))
1368 * ncp should not have picked up any refs. Physically
1371 KKASSERT(ncp->nc_refs == 1);
1373 /* cache_unlock(ncp) not required */
1374 ncp->nc_refs = -1; /* safety */
1376 free(ncp->nc_name, M_VFSCACHE);
1377 free(ncp, M_VFSCACHE);
1380 * Loop on the parent (it may be NULL). Only bother looping
1381 * if the parent has a single ref (ours), which also means
1382 * we can lock it trivially.
1387 if (ncp->nc_refs != 1) {
1391 KKASSERT(par->nc_exlocks == 0);
1399 static enum { CHI_LOW, CHI_HIGH } cache_hysteresis_state = CHI_LOW;
1403 cache_hysteresis(void)
1406 * Don't cache too many negative hits. We use hysteresis to reduce
1407 * the impact on the critical path.
1409 switch(cache_hysteresis_state) {
1411 if (numneg > MINNEG && numneg * ncnegfactor > numcache) {
1413 cache_hysteresis_state = CHI_HIGH;
1417 if (numneg > MINNEG * 9 / 10 &&
1418 numneg * ncnegfactor * 9 / 10 > numcache
1422 cache_hysteresis_state = CHI_LOW;
1429 * NEW NAMECACHE LOOKUP API
1431 * Lookup an entry in the cache. A locked, referenced, non-NULL
1432 * entry is *always* returned, even if the supplied component is illegal.
1433 * The resulting namecache entry should be returned to the system with
1434 * cache_put() or cache_unlock() + cache_drop().
1436 * namecache locks are recursive but care must be taken to avoid lock order
1439 * Nobody else will be able to manipulate the associated namespace (e.g.
1440 * create, delete, rename, rename-target) until the caller unlocks the
1443 * The returned entry will be in one of three states: positive hit (non-null
1444 * vnode), negative hit (null vnode), or unresolved (NCF_UNRESOLVED is set).
1445 * Unresolved entries must be resolved through the filesystem to associate the
1446 * vnode and/or determine whether a positive or negative hit has occured.
1448 * It is not necessary to lock a directory in order to lock namespace under
1449 * that directory. In fact, it is explicitly not allowed to do that. A
1450 * directory is typically only locked when being created, renamed, or
1453 * The directory (par) may be unresolved, in which case any returned child
1454 * will likely also be marked unresolved. Likely but not guarenteed. Since
1455 * the filesystem lookup requires a resolved directory vnode the caller is
1456 * responsible for resolving the namecache chain top-down. This API
1457 * specifically allows whole chains to be created in an unresolved state.
1460 cache_nlookup(struct namecache *par, struct nlcomponent *nlc)
1462 struct namecache *ncp;
1463 struct namecache *new_ncp;
1464 struct nchashhead *nchpp;
1472 * Try to locate an existing entry
1474 hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT);
1475 hash = fnv_32_buf(&par, sizeof(par), hash);
1478 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
1482 * Zap entries that have timed out.
1484 if (ncp->nc_timeout &&
1485 (int)(ncp->nc_timeout - ticks) < 0 &&
1486 (ncp->nc_flag & NCF_UNRESOLVED) == 0 &&
1487 ncp->nc_exlocks == 0
1489 cache_zap(cache_get(ncp));
1494 * Break out if we find a matching entry. Note that
1495 * UNRESOLVED entries may match, but DESTROYED entries
1498 if (ncp->nc_parent == par &&
1499 ncp->nc_nlen == nlc->nlc_namelen &&
1500 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 &&
1501 (ncp->nc_flag & NCF_DESTROYED) == 0
1503 if (cache_get_nonblock(ncp) == 0) {
1505 cache_free(new_ncp);
1515 * We failed to locate an entry, create a new entry and add it to
1516 * the cache. We have to relookup after possibly blocking in
1519 if (new_ncp == NULL) {
1520 new_ncp = cache_alloc(nlc->nlc_namelen);
1527 * Initialize as a new UNRESOLVED entry, lock (non-blocking),
1528 * and link to the parent. The mount point is usually inherited
1529 * from the parent unless this is a special case such as a mount
1530 * point where nlc_namelen is 0. The caller is responsible for
1531 * setting nc_mount in that case. If nlc_namelen is 0 nc_name will
1534 if (nlc->nlc_namelen) {
1535 bcopy(nlc->nlc_nameptr, ncp->nc_name, nlc->nlc_namelen);
1536 ncp->nc_name[nlc->nlc_namelen] = 0;
1537 ncp->nc_mount = par->nc_mount;
1539 nchpp = NCHHASH(hash);
1540 LIST_INSERT_HEAD(nchpp, ncp, nc_hash);
1541 ncp->nc_flag |= NCF_HASHED;
1542 cache_link_parent(ncp, par);
1545 * stats and namecache size management
1547 if (ncp->nc_flag & NCF_UNRESOLVED)
1548 ++gd->gd_nchstats->ncs_miss;
1549 else if (ncp->nc_vp)
1550 ++gd->gd_nchstats->ncs_goodhits;
1552 ++gd->gd_nchstats->ncs_neghits;
1558 * Given a locked ncp, validate that the vnode, if present, is actually
1559 * usable. If it is not usable set the ncp to an unresolved state.
1562 cache_validate(struct namecache *ncp)
1564 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
1565 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
1566 cache_setunresolved(ncp);
1571 * Resolve an unresolved namecache entry, generally by looking it up.
1572 * The passed ncp must be locked and refd.
1574 * Theoretically since a vnode cannot be recycled while held, and since
1575 * the nc_parent chain holds its vnode as long as children exist, the
1576 * direct parent of the cache entry we are trying to resolve should
1577 * have a valid vnode. If not then generate an error that we can
1578 * determine is related to a resolver bug.
1580 * However, if a vnode was in the middle of a recyclement when the NCP
1581 * got locked, ncp->nc_vp might point to a vnode that is about to become
1582 * invalid. cache_resolve() handles this case by unresolving the entry
1583 * and then re-resolving it.
1585 * Note that successful resolution does not necessarily return an error
1586 * code of 0. If the ncp resolves to a negative cache hit then ENOENT
1590 cache_resolve(struct namecache *ncp, struct ucred *cred)
1592 struct namecache *par;
1597 * If the ncp is already resolved we have nothing to do. However,
1598 * we do want to guarentee that a usable vnode is returned when
1599 * a vnode is present, so make sure it hasn't been reclaimed.
1601 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
1602 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
1603 cache_setunresolved(ncp);
1604 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0)
1605 return (ncp->nc_error);
1609 * Mount points need special handling because the parent does not
1610 * belong to the same filesystem as the ncp.
1612 if (ncp->nc_flag & NCF_MOUNTPT)
1613 return (cache_resolve_mp(ncp));
1616 * We expect an unbroken chain of ncps to at least the mount point,
1617 * and even all the way to root (but this code doesn't have to go
1618 * past the mount point).
1620 if (ncp->nc_parent == NULL) {
1621 printf("EXDEV case 1 %p %*.*s\n", ncp,
1622 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name);
1623 ncp->nc_error = EXDEV;
1624 return(ncp->nc_error);
1628 * The vp's of the parent directories in the chain are held via vhold()
1629 * due to the existance of the child, and should not disappear.
1630 * However, there are cases where they can disappear:
1632 * - due to filesystem I/O errors.
1633 * - due to NFS being stupid about tracking the namespace and
1634 * destroys the namespace for entire directories quite often.
1635 * - due to forced unmounts.
1636 * - due to an rmdir (parent will be marked DESTROYED)
1638 * When this occurs we have to track the chain backwards and resolve
1639 * it, looping until the resolver catches up to the current node. We
1640 * could recurse here but we might run ourselves out of kernel stack
1641 * so we do it in a more painful manner. This situation really should
1642 * not occur all that often, or if it does not have to go back too
1643 * many nodes to resolve the ncp.
1645 while (ncp->nc_parent->nc_vp == NULL) {
1647 * This case can occur if a process is CD'd into a
1648 * directory which is then rmdir'd. If the parent is marked
1649 * destroyed there is no point trying to resolve it.
1651 if (ncp->nc_parent->nc_flag & NCF_DESTROYED)
1654 par = ncp->nc_parent;
1655 while (par->nc_parent && par->nc_parent->nc_vp == NULL)
1656 par = par->nc_parent;
1657 if (par->nc_parent == NULL) {
1658 printf("EXDEV case 2 %*.*s\n",
1659 par->nc_nlen, par->nc_nlen, par->nc_name);
1662 printf("[diagnostic] cache_resolve: had to recurse on %*.*s\n",
1663 par->nc_nlen, par->nc_nlen, par->nc_name);
1665 * The parent is not set in stone, ref and lock it to prevent
1666 * it from disappearing. Also note that due to renames it
1667 * is possible for our ncp to move and for par to no longer
1668 * be one of its parents. We resolve it anyway, the loop
1669 * will handle any moves.
1672 if (par->nc_flag & NCF_MOUNTPT) {
1673 cache_resolve_mp(par);
1674 } else if (par->nc_parent->nc_vp == NULL) {
1675 printf("[diagnostic] cache_resolve: raced on %*.*s\n", par->nc_nlen, par->nc_nlen, par->nc_name);
1678 } else if (par->nc_flag & NCF_UNRESOLVED) {
1679 par->nc_error = VOP_NRESOLVE(par, cred);
1681 if ((error = par->nc_error) != 0) {
1682 if (par->nc_error != EAGAIN) {
1683 printf("EXDEV case 3 %*.*s error %d\n",
1684 par->nc_nlen, par->nc_nlen, par->nc_name,
1689 printf("[diagnostic] cache_resolve: EAGAIN par %p %*.*s\n",
1690 par, par->nc_nlen, par->nc_nlen, par->nc_name);
1697 * Call VOP_NRESOLVE() to get the vp, then scan for any disconnected
1698 * ncp's and reattach them. If this occurs the original ncp is marked
1699 * EAGAIN to force a relookup.
1701 * NOTE: in order to call VOP_NRESOLVE(), the parent of the passed
1702 * ncp must already be resolved.
1704 KKASSERT((ncp->nc_flag & NCF_MOUNTPT) == 0);
1705 ncp->nc_error = VOP_NRESOLVE(ncp, cred);
1706 /*vop_nresolve(*ncp->nc_parent->nc_vp->v_ops, ncp, cred);*/
1707 if (ncp->nc_error == EAGAIN) {
1708 printf("[diagnostic] cache_resolve: EAGAIN ncp %p %*.*s\n",
1709 ncp, ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name);
1712 return(ncp->nc_error);
1716 * Resolve the ncp associated with a mount point. Such ncp's almost always
1717 * remain resolved and this routine is rarely called. NFS MPs tends to force
1718 * re-resolution more often due to its mac-truck-smash-the-namecache
1719 * method of tracking namespace changes.
1721 * The semantics for this call is that the passed ncp must be locked on
1722 * entry and will be locked on return. However, if we actually have to
1723 * resolve the mount point we temporarily unlock the entry in order to
1724 * avoid race-to-root deadlocks due to e.g. dead NFS mounts. Because of
1725 * the unlock we have to recheck the flags after we relock.
1728 cache_resolve_mp(struct namecache *ncp)
1731 struct mount *mp = ncp->nc_mount;
1734 KKASSERT(mp != NULL);
1737 * If the ncp is already resolved we have nothing to do. However,
1738 * we do want to guarentee that a usable vnode is returned when
1739 * a vnode is present, so make sure it hasn't been reclaimed.
1741 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
1742 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
1743 cache_setunresolved(ncp);
1746 if (ncp->nc_flag & NCF_UNRESOLVED) {
1748 while (vfs_busy(mp, 0))
1750 error = VFS_ROOT(mp, &vp);
1754 * recheck the ncp state after relocking.
1756 if (ncp->nc_flag & NCF_UNRESOLVED) {
1757 ncp->nc_error = error;
1759 cache_setvp(ncp, vp);
1762 printf("[diagnostic] cache_resolve_mp: failed to resolve mount %p\n", mp);
1763 cache_setvp(ncp, NULL);
1765 } else if (error == 0) {
1770 return(ncp->nc_error);
1774 cache_cleanneg(int count)
1776 struct namecache *ncp;
1779 * Automode from the vnlru proc - clean out 10% of the negative cache
1783 count = numneg / 10 + 1;
1786 * Attempt to clean out the specified number of negative cache
1790 ncp = TAILQ_FIRST(&ncneglist);
1792 KKASSERT(numneg == 0);
1795 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode);
1796 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode);
1797 if (cache_get_nonblock(ncp) == 0)
1804 * Rehash a ncp. Rehashing is typically required if the name changes (should
1805 * not generally occur) or the parent link changes. This function will
1806 * unhash the ncp if the ncp is no longer hashable.
1809 cache_rehash(struct namecache *ncp)
1811 struct nchashhead *nchpp;
1814 if (ncp->nc_flag & NCF_HASHED) {
1815 ncp->nc_flag &= ~NCF_HASHED;
1816 LIST_REMOVE(ncp, nc_hash);
1818 if (ncp->nc_nlen && ncp->nc_parent) {
1819 hash = fnv_32_buf(ncp->nc_name, ncp->nc_nlen, FNV1_32_INIT);
1820 hash = fnv_32_buf(&ncp->nc_parent,
1821 sizeof(ncp->nc_parent), hash);
1822 nchpp = NCHHASH(hash);
1823 LIST_INSERT_HEAD(nchpp, ncp, nc_hash);
1824 ncp->nc_flag |= NCF_HASHED;
1829 * Name cache initialization, from vfsinit() when we are booting
1837 /* initialise per-cpu namecache effectiveness statistics. */
1838 for (i = 0; i < ncpus; ++i) {
1839 gd = globaldata_find(i);
1840 gd->gd_nchstats = &nchstats[i];
1842 TAILQ_INIT(&ncneglist);
1843 nchashtbl = hashinit(desiredvnodes*2, M_VFSCACHE, &nchash);
1844 nclockwarn = 1 * hz;
1848 * Called from start_init() to bootstrap the root filesystem. Returns
1849 * a referenced, unlocked namecache record.
1852 cache_allocroot(struct mount *mp, struct vnode *vp)
1854 struct namecache *ncp = cache_alloc(0);
1856 ncp->nc_flag |= NCF_MOUNTPT | NCF_ROOT;
1858 cache_setvp(ncp, vp);
1863 * vfs_cache_setroot()
1865 * Create an association between the root of our namecache and
1866 * the root vnode. This routine may be called several times during
1869 * If the caller intends to save the returned namecache pointer somewhere
1870 * it must cache_hold() it.
1873 vfs_cache_setroot(struct vnode *nvp, struct namecache *ncp)
1876 struct namecache *oncp;
1890 * XXX OLD API COMPAT FUNCTION. This really messes up the new namecache
1891 * topology and is being removed as quickly as possible. The new VOP_N*()
1892 * API calls are required to make specific adjustments using the supplied
1893 * ncp pointers rather then just bogusly purging random vnodes.
1895 * Invalidate all namecache entries to a particular vnode as well as
1896 * any direct children of that vnode in the namecache. This is a
1897 * 'catch all' purge used by filesystems that do not know any better.
1899 * A new vnode v_id is generated. Note that no vnode will ever have a
1902 * Note that the linkage between the vnode and its namecache entries will
1903 * be removed, but the namecache entries themselves might stay put due to
1904 * active references from elsewhere in the system or due to the existance of
1905 * the children. The namecache topology is left intact even if we do not
1906 * know what the vnode association is. Such entries will be marked
1909 * XXX: Only time and the size of v_id prevents this from failing:
1910 * XXX: In theory we should hunt down all (struct vnode*, v_id)
1911 * XXX: soft references and nuke them, at least on the global
1912 * XXX: v_id wraparound. The period of resistance can be extended
1913 * XXX: by incrementing each vnodes v_id individually instead of
1914 * XXX: using the global v_id.
1917 cache_purge(struct vnode *vp)
1919 static u_long nextid;
1921 cache_inval_vp(vp, CINV_DESTROY | CINV_CHILDREN);
1924 * Calculate a new unique id for ".." handling
1928 } while (nextid == vp->v_id || nextid == 0);
1933 * Flush all entries referencing a particular filesystem.
1935 * Since we need to check it anyway, we will flush all the invalid
1936 * entries at the same time.
1939 cache_purgevfs(struct mount *mp)
1941 struct nchashhead *nchpp;
1942 struct namecache *ncp, *nnp;
1945 * Scan hash tables for applicable entries.
1947 for (nchpp = &nchashtbl[nchash]; nchpp >= nchashtbl; nchpp--) {
1948 ncp = LIST_FIRST(nchpp);
1952 nnp = LIST_NEXT(ncp, nc_hash);
1955 if (ncp->nc_mount == mp) {
1967 * Create a new (theoretically) unique fsmid
1970 cache_getnewfsmid(void)
1972 static int fsmid_roller;
1976 fsmid = ((int64_t)time_second << 32) |
1977 (fsmid_roller & 0x7FFFFFFF);
1982 static int disablecwd;
1983 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, "");
1985 static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls);
1986 static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1);
1987 static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2);
1988 static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3);
1989 static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4);
1990 static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound);
1993 __getcwd(struct __getcwd_args *uap)
2003 buflen = uap->buflen;
2006 if (buflen > MAXPATHLEN)
2007 buflen = MAXPATHLEN;
2009 buf = malloc(buflen, M_TEMP, M_WAITOK);
2010 bp = kern_getcwd(buf, buflen, &error);
2012 error = copyout(bp, uap->buf, strlen(bp) + 1);
2018 kern_getcwd(char *buf, size_t buflen, int *error)
2020 struct proc *p = curproc;
2022 int i, slash_prefixed;
2023 struct filedesc *fdp;
2024 struct namecache *ncp;
2033 ncp = fdp->fd_ncdir;
2034 while (ncp && ncp != fdp->fd_nrdir && (ncp->nc_flag & NCF_ROOT) == 0) {
2035 if (ncp->nc_flag & NCF_MOUNTPT) {
2036 if (ncp->nc_mount == NULL) {
2037 *error = EBADF; /* forced unmount? */
2040 ncp = ncp->nc_parent;
2043 for (i = ncp->nc_nlen - 1; i >= 0; i--) {
2049 *--bp = ncp->nc_name[i];
2058 ncp = ncp->nc_parent;
2065 if (!slash_prefixed) {
2079 * Thus begins the fullpath magic.
2083 #define STATNODE(name) \
2084 static u_int name; \
2085 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "")
2087 static int disablefullpath;
2088 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW,
2089 &disablefullpath, 0, "");
2091 STATNODE(numfullpathcalls);
2092 STATNODE(numfullpathfail1);
2093 STATNODE(numfullpathfail2);
2094 STATNODE(numfullpathfail3);
2095 STATNODE(numfullpathfail4);
2096 STATNODE(numfullpathfound);
2099 cache_fullpath(struct proc *p, struct namecache *ncp, char **retbuf, char **freebuf)
2102 int i, slash_prefixed;
2103 struct namecache *fd_nrdir;
2107 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
2108 bp = buf + MAXPATHLEN - 1;
2111 fd_nrdir = p->p_fd->fd_nrdir;
2115 while (ncp && ncp != fd_nrdir && (ncp->nc_flag & NCF_ROOT) == 0) {
2116 if (ncp->nc_flag & NCF_MOUNTPT) {
2117 if (ncp->nc_mount == NULL) {
2121 ncp = ncp->nc_parent;
2124 for (i = ncp->nc_nlen - 1; i >= 0; i--) {
2130 *--bp = ncp->nc_name[i];
2139 ncp = ncp->nc_parent;
2146 if (p != NULL && (ncp->nc_flag & NCF_ROOT) && ncp != fd_nrdir) {
2147 bp = buf + MAXPATHLEN - 1;
2151 if (!slash_prefixed) {
2167 vn_fullpath(struct proc *p, struct vnode *vn, char **retbuf, char **freebuf)
2169 struct namecache *ncp;
2172 if (disablefullpath)
2178 /* vn is NULL, client wants us to use p->p_textvp */
2180 if ((vn = p->p_textvp) == NULL)
2183 TAILQ_FOREACH(ncp, &vn->v_namecache, nc_vnode) {
2191 return(cache_fullpath(p, ncp, retbuf, freebuf));