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.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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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31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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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58 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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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 1.77 2006/09/19 16:06:11 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 from outside this source module if
207 * nc_refs is already at least 1.
209 * This is a rare case where callers are allowed to hold a spinlock,
210 * so we can't ourselves.
214 _cache_hold(struct namecache *ncp)
216 atomic_add_int(&ncp->nc_refs, 1);
221 * When dropping an entry, if only one ref remains and the entry has not
222 * been resolved, zap it. Since the one reference is being dropped the
223 * entry had better not be locked.
227 _cache_drop(struct namecache *ncp)
229 KKASSERT(ncp->nc_refs > 0);
230 if (ncp->nc_refs == 1 &&
231 (ncp->nc_flag & NCF_UNRESOLVED) &&
232 TAILQ_EMPTY(&ncp->nc_list)
234 KKASSERT(ncp->nc_exlocks == 0);
238 atomic_subtract_int(&ncp->nc_refs, 1);
243 * Link a new namecache entry to its parent. Be careful to avoid races
244 * if vhold() blocks in the future.
247 cache_link_parent(struct namecache *ncp, struct namecache *par)
249 KKASSERT(ncp->nc_parent == NULL);
250 ncp->nc_parent = par;
251 if (TAILQ_EMPTY(&par->nc_list)) {
252 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry);
254 * Any vp associated with an ncp which has children must
255 * be held to prevent it from being recycled.
260 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry);
265 * Remove the parent association from a namecache structure. If this is
266 * the last child of the parent the cache_drop(par) will attempt to
267 * recursively zap the parent.
270 cache_unlink_parent(struct namecache *ncp)
272 struct namecache *par;
274 if ((par = ncp->nc_parent) != NULL) {
275 ncp->nc_parent = NULL;
276 par = cache_hold(par);
277 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry);
278 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list))
285 * Allocate a new namecache structure. Most of the code does not require
286 * zero-termination of the string but it makes vop_compat_ncreate() easier.
288 static struct namecache *
289 cache_alloc(int nlen)
291 struct namecache *ncp;
293 ncp = kmalloc(sizeof(*ncp), M_VFSCACHE, M_WAITOK|M_ZERO);
295 ncp->nc_name = kmalloc(nlen + 1, M_VFSCACHE, M_WAITOK);
297 ncp->nc_flag = NCF_UNRESOLVED;
298 ncp->nc_error = ENOTCONN; /* needs to be resolved */
302 * Construct a fake FSMID based on the time of day and a 32 bit
303 * roller for uniqueness. This is used to generate a useful
304 * FSMID for filesystems which do not support it.
306 ncp->nc_fsmid = cache_getnewfsmid();
307 TAILQ_INIT(&ncp->nc_list);
313 cache_free(struct namecache *ncp)
315 KKASSERT(ncp->nc_refs == 1 && ncp->nc_exlocks == 1);
317 kfree(ncp->nc_name, M_VFSCACHE);
318 kfree(ncp, M_VFSCACHE);
322 * Ref and deref a namecache structure.
324 * Warning: caller may hold an unrelated read spinlock, which means we can't
325 * use read spinlocks here.
328 cache_hold(struct namecache *ncp)
330 return(_cache_hold(ncp));
334 cache_drop(struct namecache *ncp)
340 * Namespace locking. The caller must already hold a reference to the
341 * namecache structure in order to lock/unlock it. This function prevents
342 * the namespace from being created or destroyed by accessors other then
345 * Note that holding a locked namecache structure prevents other threads
346 * from making namespace changes (e.g. deleting or creating), prevents
347 * vnode association state changes by other threads, and prevents the
348 * namecache entry from being resolved or unresolved by other threads.
350 * The lock owner has full authority to associate/disassociate vnodes
351 * and resolve/unresolve the locked ncp.
353 * WARNING! Holding a locked ncp will prevent a vnode from being destroyed
354 * or recycled, but it does NOT help you if the vnode had already initiated
355 * a recyclement. If this is important, use cache_get() rather then
356 * cache_lock() (and deal with the differences in the way the refs counter
357 * is handled). Or, alternatively, make an unconditional call to
358 * cache_validate() or cache_resolve() after cache_lock() returns.
361 cache_lock(struct namecache *ncp)
366 KKASSERT(ncp->nc_refs != 0);
371 if (ncp->nc_exlocks == 0) {
375 * The vp associated with a locked ncp must be held
376 * to prevent it from being recycled (which would
377 * cause the ncp to become unresolved).
379 * WARNING! If VRECLAIMED is set the vnode could
380 * already be in the middle of a recycle. Callers
381 * should not assume that nc_vp is usable when
382 * not NULL. cache_vref() or cache_vget() must be
385 * XXX loop on race for later MPSAFE work.
391 if (ncp->nc_locktd == td) {
395 ncp->nc_flag |= NCF_LOCKREQ;
396 if (tsleep(ncp, 0, "clock", nclockwarn) == EWOULDBLOCK) {
400 printf("[diagnostic] cache_lock: blocked on %p", ncp);
401 if ((ncp->nc_flag & NCF_MOUNTPT) && ncp->nc_mount)
402 printf(" [MOUNTFROM %s]\n", ncp->nc_mount->mnt_stat.f_mntfromname);
404 printf(" \"%*.*s\"\n",
405 ncp->nc_nlen, ncp->nc_nlen,
411 printf("[diagnostic] cache_lock: unblocked %*.*s\n",
412 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name);
417 cache_lock_nonblock(struct namecache *ncp)
421 KKASSERT(ncp->nc_refs != 0);
423 if (ncp->nc_exlocks == 0) {
427 * The vp associated with a locked ncp must be held
428 * to prevent it from being recycled (which would
429 * cause the ncp to become unresolved).
431 * WARNING! If VRECLAIMED is set the vnode could
432 * already be in the middle of a recycle. Callers
433 * should not assume that nc_vp is usable when
434 * not NULL. cache_vref() or cache_vget() must be
437 * XXX loop on race for later MPSAFE work.
448 cache_unlock(struct namecache *ncp)
450 thread_t td = curthread;
452 KKASSERT(ncp->nc_refs > 0);
453 KKASSERT(ncp->nc_exlocks > 0);
454 KKASSERT(ncp->nc_locktd == td);
455 if (--ncp->nc_exlocks == 0) {
458 ncp->nc_locktd = NULL;
459 if (ncp->nc_flag & NCF_LOCKREQ) {
460 ncp->nc_flag &= ~NCF_LOCKREQ;
467 * ref-and-lock, unlock-and-deref functions.
469 * This function is primarily used by nlookup. Even though cache_lock
470 * holds the vnode, it is possible that the vnode may have already
471 * initiated a recyclement. We want cache_get() to return a definitively
472 * usable vnode or a definitively unresolved ncp.
475 cache_get(struct namecache *ncp)
479 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
480 cache_setunresolved(ncp);
485 cache_get_nonblock(struct namecache *ncp)
488 if (ncp->nc_exlocks == 0 || ncp->nc_locktd == curthread) {
491 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
492 cache_setunresolved(ncp);
499 cache_put(struct namecache *ncp)
506 * Resolve an unresolved ncp by associating a vnode with it. If the
507 * vnode is NULL, a negative cache entry is created.
509 * The ncp should be locked on entry and will remain locked on return.
512 cache_setvp(struct namecache *ncp, struct vnode *vp)
514 KKASSERT(ncp->nc_flag & NCF_UNRESOLVED);
518 * Any vp associated with an ncp which has children must
519 * be held. Any vp associated with a locked ncp must be held.
521 if (!TAILQ_EMPTY(&ncp->nc_list))
523 TAILQ_INSERT_HEAD(&vp->v_namecache, ncp, nc_vnode);
528 * Set auxillary flags
532 ncp->nc_flag |= NCF_ISDIR;
535 ncp->nc_flag |= NCF_ISSYMLINK;
536 /* XXX cache the contents of the symlink */
544 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode);
546 ncp->nc_error = ENOENT;
548 ncp->nc_flag &= ~NCF_UNRESOLVED;
552 cache_settimeout(struct namecache *ncp, int nticks)
554 if ((ncp->nc_timeout = ticks + nticks) == 0)
559 * Disassociate the vnode or negative-cache association and mark a
560 * namecache entry as unresolved again. Note that the ncp is still
561 * left in the hash table and still linked to its parent.
563 * The ncp should be locked and refd on entry and will remain locked and refd
566 * This routine is normally never called on a directory containing children.
567 * However, NFS often does just that in its rename() code as a cop-out to
568 * avoid complex namespace operations. This disconnects a directory vnode
569 * from its namecache and can cause the OLDAPI and NEWAPI to get out of
572 * NOTE: NCF_FSMID must be cleared so a refurbishment of the ncp, such as
573 * in a create, properly propogates flag up the chain.
576 cache_setunresolved(struct namecache *ncp)
580 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
581 ncp->nc_flag |= NCF_UNRESOLVED;
583 ncp->nc_error = ENOTCONN;
585 if ((vp = ncp->nc_vp) != NULL) {
588 TAILQ_REMOVE(&vp->v_namecache, ncp, nc_vnode);
591 * Any vp associated with an ncp with children is
592 * held by that ncp. Any vp associated with a locked
593 * ncp is held by that ncp. These conditions must be
594 * undone when the vp is cleared out from the ncp.
596 if (ncp->nc_flag & NCF_FSMID)
598 if (!TAILQ_EMPTY(&ncp->nc_list))
603 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode);
606 ncp->nc_flag &= ~(NCF_WHITEOUT|NCF_ISDIR|NCF_ISSYMLINK|
612 * Mark the namecache node as containing a mount point.
614 * XXX called with a ref'd but unlocked ncp.
617 cache_setmountpt(struct namecache *ncp, struct mount *mp)
620 ncp->nc_flag |= NCF_MOUNTPT;
621 ncp->nc_parent->nc_flag |= NCF_MOUNTEDHERE;
625 * Clean up a mount point in the namecache topology after an unmount.
627 * XXX we probably need to traverse the entire topology and clear
628 * the nc_mount pointer.
631 cache_clrmountpt(struct namecache *ncp)
634 ncp->nc_parent->nc_flag &= ~NCF_MOUNTEDHERE;
635 ncp->nc_mount = NULL;
639 * Invalidate portions of the namecache topology given a starting entry.
640 * The passed ncp is set to an unresolved state and:
642 * The passed ncp must be locked.
644 * CINV_DESTROY - Set a flag in the passed ncp entry indicating
645 * that the physical underlying nodes have been
646 * destroyed... as in deleted. For example, when
647 * a directory is removed. This will cause record
648 * lookups on the name to no longer be able to find
649 * the record and tells the resolver to return failure
650 * rather then trying to resolve through the parent.
652 * The topology itself, including ncp->nc_name,
655 * This only applies to the passed ncp, if CINV_CHILDREN
656 * is specified the children are not flagged.
658 * CINV_CHILDREN - Set all children (recursively) to an unresolved
661 * Note that this will also have the side effect of
662 * cleaning out any unreferenced nodes in the topology
663 * from the leaves up as the recursion backs out.
665 * Note that the topology for any referenced nodes remains intact.
667 * It is possible for cache_inval() to race a cache_resolve(), meaning that
668 * the namecache entry may not actually be invalidated on return if it was
669 * revalidated while recursing down into its children. This code guarentees
670 * that the node(s) will go through an invalidation cycle, but does not
671 * guarentee that they will remain in an invalidated state.
673 * Returns non-zero if a revalidation was detected during the invalidation
674 * recursion, zero otherwise. Note that since only the original ncp is
675 * locked the revalidation ultimately can only indicate that the original ncp
676 * *MIGHT* no have been reresolved.
679 cache_inval(struct namecache *ncp, int flags)
681 struct namecache *kid;
682 struct namecache *nextkid;
685 KKASSERT(ncp->nc_exlocks);
687 cache_setunresolved(ncp);
688 if (flags & CINV_DESTROY)
689 ncp->nc_flag |= NCF_DESTROYED;
691 if ((flags & CINV_CHILDREN) &&
692 (kid = TAILQ_FIRST(&ncp->nc_list)) != NULL
697 if ((nextkid = TAILQ_NEXT(kid, nc_entry)) != NULL)
699 if ((kid->nc_flag & NCF_UNRESOLVED) == 0 ||
700 TAILQ_FIRST(&kid->nc_list)
703 rcnt += cache_inval(kid, flags & ~CINV_DESTROY);
713 * Someone could have gotten in there while ncp was unlocked,
716 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0)
722 * Invalidate a vnode's namecache associations. To avoid races against
723 * the resolver we do not invalidate a node which we previously invalidated
724 * but which was then re-resolved while we were in the invalidation loop.
726 * Returns non-zero if any namecache entries remain after the invalidation
729 * NOTE: unlike the namecache topology which guarentees that ncp's will not
730 * be ripped out of the topology while held, the vnode's v_namecache list
731 * has no such restriction. NCP's can be ripped out of the list at virtually
732 * any time if not locked, even if held.
735 cache_inval_vp(struct vnode *vp, int flags)
737 struct namecache *ncp;
738 struct namecache *next;
741 ncp = TAILQ_FIRST(&vp->v_namecache);
745 /* loop entered with ncp held */
746 if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL)
749 if (ncp->nc_vp != vp) {
750 printf("Warning: cache_inval_vp: race-A detected on "
751 "%s\n", ncp->nc_name);
757 cache_inval(ncp, flags);
758 cache_put(ncp); /* also releases reference */
760 if (ncp && ncp->nc_vp != vp) {
761 printf("Warning: cache_inval_vp: race-B detected on "
762 "%s\n", ncp->nc_name);
767 return(TAILQ_FIRST(&vp->v_namecache) != NULL);
771 * The source ncp has been renamed to the target ncp. Both fncp and tncp
772 * must be locked. Both will be set to unresolved, any children of tncp
773 * will be disconnected (the prior contents of the target is assumed to be
774 * destroyed by the rename operation, e.g. renaming over an empty directory),
775 * and all children of fncp will be moved to tncp.
777 * XXX the disconnection could pose a problem, check code paths to make
778 * sure any code that blocks can handle the parent being changed out from
779 * under it. Maybe we should lock the children (watch out for deadlocks) ?
781 * After we return the caller has the option of calling cache_setvp() if
782 * the vnode of the new target ncp is known.
784 * Any process CD'd into any of the children will no longer be able to ".."
785 * back out. An rm -rf can cause this situation to occur.
788 cache_rename(struct namecache *fncp, struct namecache *tncp)
790 struct namecache *scan;
793 cache_setunresolved(fncp);
794 cache_setunresolved(tncp);
795 while (cache_inval(tncp, CINV_CHILDREN) != 0) {
796 if (didwarn++ % 10 == 0) {
797 printf("Warning: cache_rename: race during "
799 fncp->nc_name, tncp->nc_name);
801 tsleep(tncp, 0, "mvrace", hz / 10);
802 cache_setunresolved(tncp);
804 while ((scan = TAILQ_FIRST(&fncp->nc_list)) != NULL) {
806 cache_unlink_parent(scan);
807 cache_link_parent(scan, tncp);
808 if (scan->nc_flag & NCF_HASHED)
815 * vget the vnode associated with the namecache entry. Resolve the namecache
816 * entry if necessary and deal with namecache/vp races. The passed ncp must
817 * be referenced and may be locked. The ncp's ref/locking state is not
818 * effected by this call.
820 * lk_type may be LK_SHARED, LK_EXCLUSIVE. A ref'd, possibly locked
821 * (depending on the passed lk_type) will be returned in *vpp with an error
822 * of 0, or NULL will be returned in *vpp with a non-0 error code. The
823 * most typical error is ENOENT, meaning that the ncp represents a negative
824 * cache hit and there is no vnode to retrieve, but other errors can occur
827 * The main race we have to deal with are namecache zaps. The ncp itself
828 * will not disappear since it is referenced, and it turns out that the
829 * validity of the vp pointer can be checked simply by rechecking the
830 * contents of ncp->nc_vp.
833 cache_vget(struct namecache *ncp, struct ucred *cred,
834 int lk_type, struct vnode **vpp)
841 if (ncp->nc_flag & NCF_UNRESOLVED) {
843 error = cache_resolve(ncp, cred);
848 if (error == 0 && (vp = ncp->nc_vp) != NULL) {
850 * Accessing the vnode from the namecache is a bit
851 * dangerous. Because there are no refs on the vnode, it
852 * could be in the middle of a reclaim.
854 if (vp->v_flag & VRECLAIMED) {
855 printf("Warning: vnode reclaim race detected in cache_vget on %p (%s)\n", vp, ncp->nc_name);
857 cache_setunresolved(ncp);
861 error = vget(vp, lk_type);
863 if (vp != ncp->nc_vp)
866 } else if (vp != ncp->nc_vp) {
869 } else if (vp->v_flag & VRECLAIMED) {
870 panic("vget succeeded on a VRECLAIMED node! vp %p", vp);
873 if (error == 0 && vp == NULL)
880 cache_vref(struct namecache *ncp, struct ucred *cred, struct vnode **vpp)
887 if (ncp->nc_flag & NCF_UNRESOLVED) {
889 error = cache_resolve(ncp, cred);
894 if (error == 0 && (vp = ncp->nc_vp) != NULL) {
896 * Since we did not obtain any locks, a cache zap
897 * race can occur here if the vnode is in the middle
898 * of being reclaimed and has not yet been able to
899 * clean out its cache node. If that case occurs,
900 * we must lock and unresolve the cache, then loop
903 if (vp->v_flag & VRECLAIMED) {
904 printf("Warning: vnode reclaim race detected on cache_vref %p (%s)\n", vp, ncp->nc_name);
906 cache_setunresolved(ncp);
912 if (error == 0 && vp == NULL)
919 * Recursively set the FSMID update flag for namecache nodes leading
920 * to root. This will cause the next getattr or reclaim to increment the
921 * fsmid and mark the inode for lazy updating.
923 * Stop recursing when we hit a node whos NCF_FSMID flag is already set.
924 * This makes FSMIDs work in an Einsteinian fashion - where the observation
925 * effects the result. In this case a program monitoring a higher level
926 * node will have detected some prior change and started its scan (clearing
927 * NCF_FSMID in higher level nodes), but since it has not yet observed the
928 * node where we find NCF_FSMID still set, we can safely make the related
929 * modification without interfering with the theorized program.
931 * This also means that FSMIDs cannot represent time-domain quantities
932 * in a hierarchical sense. But the main reason for doing it this way
933 * is to reduce the amount of recursion that occurs in the critical path
934 * when e.g. a program is writing to a file that sits deep in a directory
938 cache_update_fsmid(struct namecache *ncp)
941 struct namecache *scan;
944 * Warning: even if we get a non-NULL vp it could still be in the
945 * middle of a recyclement. Don't do anything fancy, just set
948 if ((vp = ncp->nc_vp) != NULL) {
949 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
950 for (scan = ncp; scan; scan = scan->nc_parent) {
951 if (scan->nc_flag & NCF_FSMID)
953 scan->nc_flag |= NCF_FSMID;
957 while (ncp && (ncp->nc_flag & NCF_FSMID) == 0) {
958 ncp->nc_flag |= NCF_FSMID;
959 ncp = ncp->nc_parent;
965 cache_update_fsmid_vp(struct vnode *vp)
967 struct namecache *ncp;
968 struct namecache *scan;
970 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
971 for (scan = ncp; scan; scan = scan->nc_parent) {
972 if (scan->nc_flag & NCF_FSMID)
974 scan->nc_flag |= NCF_FSMID;
980 * If getattr is called on a vnode (e.g. a stat call), the filesystem
981 * may call this routine to determine if the namecache has the hierarchical
982 * change flag set, requiring the fsmid to be updated.
984 * Since 0 indicates no support, make sure the filesystem fsmid is at least
988 cache_check_fsmid_vp(struct vnode *vp, int64_t *fsmid)
990 struct namecache *ncp;
993 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
994 if (ncp->nc_flag & NCF_FSMID) {
995 ncp->nc_flag &= ~NCF_FSMID;
1007 * Obtain the FSMID for a vnode for filesystems which do not support
1011 cache_sync_fsmid_vp(struct vnode *vp)
1013 struct namecache *ncp;
1015 if ((ncp = TAILQ_FIRST(&vp->v_namecache)) != NULL) {
1016 if (ncp->nc_flag & NCF_FSMID) {
1017 ncp->nc_flag &= ~NCF_FSMID;
1020 return(ncp->nc_fsmid);
1026 * Convert a directory vnode to a namecache record without any other
1027 * knowledge of the topology. This ONLY works with directory vnodes and
1028 * is ONLY used by the NFS server. dvp must be refd but unlocked, and the
1029 * returned ncp (if not NULL) will be held and unlocked.
1031 * If 'makeit' is 0 and dvp has no existing namecache record, NULL is returned.
1032 * If 'makeit' is 1 we attempt to track-down and create the namecache topology
1033 * for dvp. This will fail only if the directory has been deleted out from
1036 * Callers must always check for a NULL return no matter the value of 'makeit'.
1038 * To avoid underflowing the kernel stack each recursive call increments
1039 * the makeit variable.
1042 static int cache_inefficient_scan(struct namecache *ncp, struct ucred *cred,
1044 static int cache_fromdvp_try(struct vnode *dvp, struct ucred *cred,
1045 struct vnode **saved_dvp);
1048 cache_fromdvp(struct vnode *dvp, struct ucred *cred, int makeit)
1050 struct namecache *ncp;
1051 struct vnode *saved_dvp;
1059 * Temporary debugging code to force the directory scanning code
1062 if (ncvp_debug >= 3 && makeit && TAILQ_FIRST(&dvp->v_namecache)) {
1063 ncp = TAILQ_FIRST(&dvp->v_namecache);
1064 printf("cache_fromdvp: forcing %s\n", ncp->nc_name);
1069 * Loop until resolution, inside code will break out on error.
1071 while ((ncp = TAILQ_FIRST(&dvp->v_namecache)) == NULL && makeit) {
1074 * If dvp is the root of its filesystem it should already
1075 * have a namecache pointer associated with it as a side
1076 * effect of the mount, but it may have been disassociated.
1078 if (dvp->v_flag & VROOT) {
1079 ncp = cache_get(dvp->v_mount->mnt_ncp);
1080 error = cache_resolve_mp(ncp);
1083 printf("cache_fromdvp: resolve root of mount %p error %d",
1084 dvp->v_mount, error);
1088 printf(" failed\n");
1093 printf(" succeeded\n");
1098 * If we are recursed too deeply resort to an O(n^2)
1099 * algorithm to resolve the namecache topology. The
1100 * resolved pvp is left referenced in saved_dvp to
1101 * prevent the tree from being destroyed while we loop.
1104 error = cache_fromdvp_try(dvp, cred, &saved_dvp);
1106 printf("lookupdotdot(longpath) failed %d "
1107 "dvp %p\n", error, dvp);
1114 * Get the parent directory and resolve its ncp.
1116 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred);
1118 printf("lookupdotdot failed %d dvp %p\n", error, dvp);
1124 * Reuse makeit as a recursion depth counter.
1126 ncp = cache_fromdvp(pvp, cred, makeit + 1);
1132 * Do an inefficient scan of pvp (embodied by ncp) to look
1133 * for dvp. This will create a namecache record for dvp on
1134 * success. We loop up to recheck on success.
1136 * ncp and dvp are both held but not locked.
1138 error = cache_inefficient_scan(ncp, cred, dvp);
1141 printf("cache_fromdvp: scan %p (%s) failed on dvp=%p\n",
1142 pvp, ncp->nc_name, dvp);
1147 printf("cache_fromdvp: scan %p (%s) succeeded\n",
1159 * Go up the chain of parent directories until we find something
1160 * we can resolve into the namecache. This is very inefficient.
1164 cache_fromdvp_try(struct vnode *dvp, struct ucred *cred,
1165 struct vnode **saved_dvp)
1167 struct namecache *ncp;
1170 static time_t last_fromdvp_report;
1173 * Loop getting the parent directory vnode until we get something we
1174 * can resolve in the namecache.
1178 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred);
1184 if ((ncp = TAILQ_FIRST(&pvp->v_namecache)) != NULL) {
1189 if (pvp->v_flag & VROOT) {
1190 ncp = cache_get(pvp->v_mount->mnt_ncp);
1191 error = cache_resolve_mp(ncp);
1204 if (last_fromdvp_report != time_second) {
1205 last_fromdvp_report = time_second;
1206 printf("Warning: extremely inefficient path resolution on %s\n",
1209 error = cache_inefficient_scan(ncp, cred, dvp);
1212 * Hopefully dvp now has a namecache record associated with it.
1213 * Leave it referenced to prevent the kernel from recycling the
1214 * vnode. Otherwise extremely long directory paths could result
1215 * in endless recycling.
1225 * Do an inefficient scan of the directory represented by ncp looking for
1226 * the directory vnode dvp. ncp must be held but not locked on entry and
1227 * will be held on return. dvp must be refd but not locked on entry and
1228 * will remain refd on return.
1230 * Why do this at all? Well, due to its stateless nature the NFS server
1231 * converts file handles directly to vnodes without necessarily going through
1232 * the namecache ops that would otherwise create the namecache topology
1233 * leading to the vnode. We could either (1) Change the namecache algorithms
1234 * to allow disconnect namecache records that are re-merged opportunistically,
1235 * or (2) Make the NFS server backtrack and scan to recover a connected
1236 * namecache topology in order to then be able to issue new API lookups.
1238 * It turns out that (1) is a huge mess. It takes a nice clean set of
1239 * namecache algorithms and introduces a lot of complication in every subsystem
1240 * that calls into the namecache to deal with the re-merge case, especially
1241 * since we are using the namecache to placehold negative lookups and the
1242 * vnode might not be immediately assigned. (2) is certainly far less
1243 * efficient then (1), but since we are only talking about directories here
1244 * (which are likely to remain cached), the case does not actually run all
1245 * that often and has the supreme advantage of not polluting the namecache
1249 cache_inefficient_scan(struct namecache *ncp, struct ucred *cred,
1252 struct nlcomponent nlc;
1253 struct namecache *rncp;
1265 vat.va_blocksize = 0;
1266 if ((error = VOP_GETATTR(dvp, &vat)) != 0)
1268 if ((error = cache_vref(ncp, cred, &pvp)) != 0)
1271 printf("inefficient_scan: directory iosize %ld vattr fileid = %ld\n", vat.va_blocksize, (long)vat.va_fileid);
1272 if ((blksize = vat.va_blocksize) == 0)
1273 blksize = DEV_BSIZE;
1274 rbuf = kmalloc(blksize, M_TEMP, M_WAITOK);
1280 iov.iov_base = rbuf;
1281 iov.iov_len = blksize;
1284 uio.uio_resid = blksize;
1285 uio.uio_segflg = UIO_SYSSPACE;
1286 uio.uio_rw = UIO_READ;
1287 uio.uio_td = curthread;
1289 if (ncvp_debug >= 2)
1290 printf("cache_inefficient_scan: readdir @ %08x\n", (int)uio.uio_offset);
1291 error = VOP_READDIR(pvp, &uio, cred, &eofflag, NULL, NULL);
1293 den = (struct dirent *)rbuf;
1294 bytes = blksize - uio.uio_resid;
1297 if (ncvp_debug >= 2) {
1298 printf("cache_inefficient_scan: %*.*s\n",
1299 den->d_namlen, den->d_namlen,
1302 if (den->d_type != DT_WHT &&
1303 den->d_ino == vat.va_fileid) {
1305 printf("cache_inefficient_scan: "
1306 "MATCHED inode %ld path %s/%*.*s\n",
1307 vat.va_fileid, ncp->nc_name,
1308 den->d_namlen, den->d_namlen,
1311 nlc.nlc_nameptr = den->d_name;
1312 nlc.nlc_namelen = den->d_namlen;
1313 rncp = cache_nlookup(ncp, &nlc);
1314 KKASSERT(rncp != NULL);
1317 bytes -= _DIRENT_DIRSIZ(den);
1318 den = _DIRENT_NEXT(den);
1320 if (rncp == NULL && eofflag == 0 && uio.uio_resid != blksize)
1325 if (rncp->nc_flag & NCF_UNRESOLVED) {
1326 cache_setvp(rncp, dvp);
1327 if (ncvp_debug >= 2) {
1328 printf("cache_inefficient_scan: setvp %s/%s = %p\n",
1329 ncp->nc_name, rncp->nc_name, dvp);
1332 if (ncvp_debug >= 2) {
1333 printf("cache_inefficient_scan: setvp %s/%s already set %p/%p\n",
1334 ncp->nc_name, rncp->nc_name, dvp,
1338 if (rncp->nc_vp == NULL)
1339 error = rncp->nc_error;
1342 printf("cache_inefficient_scan: dvp %p NOT FOUND in %s\n",
1346 kfree(rbuf, M_TEMP);
1351 * Zap a namecache entry. The ncp is unconditionally set to an unresolved
1352 * state, which disassociates it from its vnode or ncneglist.
1354 * Then, if there are no additional references to the ncp and no children,
1355 * the ncp is removed from the topology and destroyed. This function will
1356 * also run through the nc_parent chain and destroy parent ncps if possible.
1357 * As a side benefit, it turns out the only conditions that allow running
1358 * up the chain are also the conditions to ensure no deadlock will occur.
1360 * References and/or children may exist if the ncp is in the middle of the
1361 * topology, preventing the ncp from being destroyed.
1363 * This function must be called with the ncp held and locked and will unlock
1364 * and drop it during zapping.
1367 cache_zap(struct namecache *ncp)
1369 struct namecache *par;
1372 * Disassociate the vnode or negative cache ref and set NCF_UNRESOLVED.
1374 cache_setunresolved(ncp);
1377 * Try to scrap the entry and possibly tail-recurse on its parent.
1378 * We only scrap unref'd (other then our ref) unresolved entries,
1379 * we do not scrap 'live' entries.
1381 while (ncp->nc_flag & NCF_UNRESOLVED) {
1383 * Someone other then us has a ref, stop.
1385 if (ncp->nc_refs > 1)
1389 * We have children, stop.
1391 if (!TAILQ_EMPTY(&ncp->nc_list))
1395 * Remove ncp from the topology: hash table and parent linkage.
1397 if (ncp->nc_flag & NCF_HASHED) {
1398 ncp->nc_flag &= ~NCF_HASHED;
1399 LIST_REMOVE(ncp, nc_hash);
1401 if ((par = ncp->nc_parent) != NULL) {
1402 par = cache_hold(par);
1403 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry);
1404 ncp->nc_parent = NULL;
1405 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list))
1410 * ncp should not have picked up any refs. Physically
1413 KKASSERT(ncp->nc_refs == 1);
1415 /* cache_unlock(ncp) not required */
1416 ncp->nc_refs = -1; /* safety */
1418 kfree(ncp->nc_name, M_VFSCACHE);
1419 kfree(ncp, M_VFSCACHE);
1422 * Loop on the parent (it may be NULL). Only bother looping
1423 * if the parent has a single ref (ours), which also means
1424 * we can lock it trivially.
1429 if (ncp->nc_refs != 1) {
1433 KKASSERT(par->nc_exlocks == 0);
1438 atomic_subtract_int(&ncp->nc_refs, 1);
1441 static enum { CHI_LOW, CHI_HIGH } cache_hysteresis_state = CHI_LOW;
1445 cache_hysteresis(void)
1448 * Don't cache too many negative hits. We use hysteresis to reduce
1449 * the impact on the critical path.
1451 switch(cache_hysteresis_state) {
1453 if (numneg > MINNEG && numneg * ncnegfactor > numcache) {
1455 cache_hysteresis_state = CHI_HIGH;
1459 if (numneg > MINNEG * 9 / 10 &&
1460 numneg * ncnegfactor * 9 / 10 > numcache
1464 cache_hysteresis_state = CHI_LOW;
1471 * NEW NAMECACHE LOOKUP API
1473 * Lookup an entry in the cache. A locked, referenced, non-NULL
1474 * entry is *always* returned, even if the supplied component is illegal.
1475 * The resulting namecache entry should be returned to the system with
1476 * cache_put() or cache_unlock() + cache_drop().
1478 * namecache locks are recursive but care must be taken to avoid lock order
1481 * Nobody else will be able to manipulate the associated namespace (e.g.
1482 * create, delete, rename, rename-target) until the caller unlocks the
1485 * The returned entry will be in one of three states: positive hit (non-null
1486 * vnode), negative hit (null vnode), or unresolved (NCF_UNRESOLVED is set).
1487 * Unresolved entries must be resolved through the filesystem to associate the
1488 * vnode and/or determine whether a positive or negative hit has occured.
1490 * It is not necessary to lock a directory in order to lock namespace under
1491 * that directory. In fact, it is explicitly not allowed to do that. A
1492 * directory is typically only locked when being created, renamed, or
1495 * The directory (par) may be unresolved, in which case any returned child
1496 * will likely also be marked unresolved. Likely but not guarenteed. Since
1497 * the filesystem lookup requires a resolved directory vnode the caller is
1498 * responsible for resolving the namecache chain top-down. This API
1499 * specifically allows whole chains to be created in an unresolved state.
1502 cache_nlookup(struct namecache *par, struct nlcomponent *nlc)
1504 struct namecache *ncp;
1505 struct namecache *new_ncp;
1506 struct nchashhead *nchpp;
1514 * Try to locate an existing entry
1516 hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT);
1517 hash = fnv_32_buf(&par, sizeof(par), hash);
1520 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
1524 * Zap entries that have timed out.
1526 if (ncp->nc_timeout &&
1527 (int)(ncp->nc_timeout - ticks) < 0 &&
1528 (ncp->nc_flag & NCF_UNRESOLVED) == 0 &&
1529 ncp->nc_exlocks == 0
1531 cache_zap(cache_get(ncp));
1536 * Break out if we find a matching entry. Note that
1537 * UNRESOLVED entries may match, but DESTROYED entries
1540 if (ncp->nc_parent == par &&
1541 ncp->nc_nlen == nlc->nlc_namelen &&
1542 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 &&
1543 (ncp->nc_flag & NCF_DESTROYED) == 0
1545 if (cache_get_nonblock(ncp) == 0) {
1547 cache_free(new_ncp);
1557 * We failed to locate an entry, create a new entry and add it to
1558 * the cache. We have to relookup after possibly blocking in
1561 if (new_ncp == NULL) {
1562 new_ncp = cache_alloc(nlc->nlc_namelen);
1569 * Initialize as a new UNRESOLVED entry, lock (non-blocking),
1570 * and link to the parent. The mount point is usually inherited
1571 * from the parent unless this is a special case such as a mount
1572 * point where nlc_namelen is 0. The caller is responsible for
1573 * setting nc_mount in that case. If nlc_namelen is 0 nc_name will
1576 if (nlc->nlc_namelen) {
1577 bcopy(nlc->nlc_nameptr, ncp->nc_name, nlc->nlc_namelen);
1578 ncp->nc_name[nlc->nlc_namelen] = 0;
1579 ncp->nc_mount = par->nc_mount;
1581 nchpp = NCHHASH(hash);
1582 LIST_INSERT_HEAD(nchpp, ncp, nc_hash);
1583 ncp->nc_flag |= NCF_HASHED;
1584 cache_link_parent(ncp, par);
1587 * stats and namecache size management
1589 if (ncp->nc_flag & NCF_UNRESOLVED)
1590 ++gd->gd_nchstats->ncs_miss;
1591 else if (ncp->nc_vp)
1592 ++gd->gd_nchstats->ncs_goodhits;
1594 ++gd->gd_nchstats->ncs_neghits;
1600 * Locate the mount point under a namecache entry. We locate a special
1601 * child ncp with a 0-length name and retrieve the mount point from it.
1604 cache_findmount(struct namecache *par)
1606 struct namecache *ncp;
1609 hash = FNV1_32_INIT; /* special 0-length name */
1610 hash = fnv_32_buf(&par, sizeof(par), hash);
1611 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
1612 if (ncp->nc_nlen == 0 && (ncp->nc_flag & NCF_MOUNTPT))
1613 return(ncp->nc_mount);
1619 * Given a locked ncp, validate that the vnode, if present, is actually
1620 * usable. If it is not usable set the ncp to an unresolved state.
1623 cache_validate(struct namecache *ncp)
1625 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
1626 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
1627 cache_setunresolved(ncp);
1632 * Resolve an unresolved namecache entry, generally by looking it up.
1633 * The passed ncp must be locked and refd.
1635 * Theoretically since a vnode cannot be recycled while held, and since
1636 * the nc_parent chain holds its vnode as long as children exist, the
1637 * direct parent of the cache entry we are trying to resolve should
1638 * have a valid vnode. If not then generate an error that we can
1639 * determine is related to a resolver bug.
1641 * However, if a vnode was in the middle of a recyclement when the NCP
1642 * got locked, ncp->nc_vp might point to a vnode that is about to become
1643 * invalid. cache_resolve() handles this case by unresolving the entry
1644 * and then re-resolving it.
1646 * Note that successful resolution does not necessarily return an error
1647 * code of 0. If the ncp resolves to a negative cache hit then ENOENT
1651 cache_resolve(struct namecache *ncp, struct ucred *cred)
1653 struct namecache *par;
1658 * If the ncp is already resolved we have nothing to do. However,
1659 * we do want to guarentee that a usable vnode is returned when
1660 * a vnode is present, so make sure it hasn't been reclaimed.
1662 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
1663 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
1664 cache_setunresolved(ncp);
1665 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0)
1666 return (ncp->nc_error);
1670 * Mount points need special handling because the parent does not
1671 * belong to the same filesystem as the ncp.
1673 if (ncp->nc_flag & NCF_MOUNTPT)
1674 return (cache_resolve_mp(ncp));
1677 * We expect an unbroken chain of ncps to at least the mount point,
1678 * and even all the way to root (but this code doesn't have to go
1679 * past the mount point).
1681 if (ncp->nc_parent == NULL) {
1682 printf("EXDEV case 1 %p %*.*s\n", ncp,
1683 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name);
1684 ncp->nc_error = EXDEV;
1685 return(ncp->nc_error);
1689 * The vp's of the parent directories in the chain are held via vhold()
1690 * due to the existance of the child, and should not disappear.
1691 * However, there are cases where they can disappear:
1693 * - due to filesystem I/O errors.
1694 * - due to NFS being stupid about tracking the namespace and
1695 * destroys the namespace for entire directories quite often.
1696 * - due to forced unmounts.
1697 * - due to an rmdir (parent will be marked DESTROYED)
1699 * When this occurs we have to track the chain backwards and resolve
1700 * it, looping until the resolver catches up to the current node. We
1701 * could recurse here but we might run ourselves out of kernel stack
1702 * so we do it in a more painful manner. This situation really should
1703 * not occur all that often, or if it does not have to go back too
1704 * many nodes to resolve the ncp.
1706 while (ncp->nc_parent->nc_vp == NULL) {
1708 * This case can occur if a process is CD'd into a
1709 * directory which is then rmdir'd. If the parent is marked
1710 * destroyed there is no point trying to resolve it.
1712 if (ncp->nc_parent->nc_flag & NCF_DESTROYED)
1715 par = ncp->nc_parent;
1716 while (par->nc_parent && par->nc_parent->nc_vp == NULL)
1717 par = par->nc_parent;
1718 if (par->nc_parent == NULL) {
1719 printf("EXDEV case 2 %*.*s\n",
1720 par->nc_nlen, par->nc_nlen, par->nc_name);
1723 printf("[diagnostic] cache_resolve: had to recurse on %*.*s\n",
1724 par->nc_nlen, par->nc_nlen, par->nc_name);
1726 * The parent is not set in stone, ref and lock it to prevent
1727 * it from disappearing. Also note that due to renames it
1728 * is possible for our ncp to move and for par to no longer
1729 * be one of its parents. We resolve it anyway, the loop
1730 * will handle any moves.
1733 if (par->nc_flag & NCF_MOUNTPT) {
1734 cache_resolve_mp(par);
1735 } else if (par->nc_parent->nc_vp == NULL) {
1736 printf("[diagnostic] cache_resolve: raced on %*.*s\n", par->nc_nlen, par->nc_nlen, par->nc_name);
1739 } else if (par->nc_flag & NCF_UNRESOLVED) {
1740 par->nc_error = VOP_NRESOLVE(par, cred);
1742 if ((error = par->nc_error) != 0) {
1743 if (par->nc_error != EAGAIN) {
1744 printf("EXDEV case 3 %*.*s error %d\n",
1745 par->nc_nlen, par->nc_nlen, par->nc_name,
1750 printf("[diagnostic] cache_resolve: EAGAIN par %p %*.*s\n",
1751 par, par->nc_nlen, par->nc_nlen, par->nc_name);
1758 * Call VOP_NRESOLVE() to get the vp, then scan for any disconnected
1759 * ncp's and reattach them. If this occurs the original ncp is marked
1760 * EAGAIN to force a relookup.
1762 * NOTE: in order to call VOP_NRESOLVE(), the parent of the passed
1763 * ncp must already be resolved.
1765 KKASSERT((ncp->nc_flag & NCF_MOUNTPT) == 0);
1766 ncp->nc_error = VOP_NRESOLVE(ncp, cred);
1767 /*vop_nresolve(*ncp->nc_parent->nc_vp->v_ops, ncp, cred);*/
1768 if (ncp->nc_error == EAGAIN) {
1769 printf("[diagnostic] cache_resolve: EAGAIN ncp %p %*.*s\n",
1770 ncp, ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name);
1773 return(ncp->nc_error);
1777 * Resolve the ncp associated with a mount point. Such ncp's almost always
1778 * remain resolved and this routine is rarely called. NFS MPs tends to force
1779 * re-resolution more often due to its mac-truck-smash-the-namecache
1780 * method of tracking namespace changes.
1782 * The semantics for this call is that the passed ncp must be locked on
1783 * entry and will be locked on return. However, if we actually have to
1784 * resolve the mount point we temporarily unlock the entry in order to
1785 * avoid race-to-root deadlocks due to e.g. dead NFS mounts. Because of
1786 * the unlock we have to recheck the flags after we relock.
1789 cache_resolve_mp(struct namecache *ncp)
1792 struct mount *mp = ncp->nc_mount;
1795 KKASSERT(mp != NULL);
1798 * If the ncp is already resolved we have nothing to do. However,
1799 * we do want to guarentee that a usable vnode is returned when
1800 * a vnode is present, so make sure it hasn't been reclaimed.
1802 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
1803 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
1804 cache_setunresolved(ncp);
1807 if (ncp->nc_flag & NCF_UNRESOLVED) {
1809 while (vfs_busy(mp, 0))
1811 error = VFS_ROOT(mp, &vp);
1815 * recheck the ncp state after relocking.
1817 if (ncp->nc_flag & NCF_UNRESOLVED) {
1818 ncp->nc_error = error;
1820 cache_setvp(ncp, vp);
1823 printf("[diagnostic] cache_resolve_mp: failed to resolve mount %p\n", mp);
1824 cache_setvp(ncp, NULL);
1826 } else if (error == 0) {
1831 return(ncp->nc_error);
1835 cache_cleanneg(int count)
1837 struct namecache *ncp;
1840 * Automode from the vnlru proc - clean out 10% of the negative cache
1844 count = numneg / 10 + 1;
1847 * Attempt to clean out the specified number of negative cache
1851 ncp = TAILQ_FIRST(&ncneglist);
1853 KKASSERT(numneg == 0);
1856 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode);
1857 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode);
1858 if (cache_get_nonblock(ncp) == 0)
1865 * Rehash a ncp. Rehashing is typically required if the name changes (should
1866 * not generally occur) or the parent link changes. This function will
1867 * unhash the ncp if the ncp is no longer hashable.
1870 cache_rehash(struct namecache *ncp)
1872 struct nchashhead *nchpp;
1875 if (ncp->nc_flag & NCF_HASHED) {
1876 ncp->nc_flag &= ~NCF_HASHED;
1877 LIST_REMOVE(ncp, nc_hash);
1879 if (ncp->nc_nlen && ncp->nc_parent) {
1880 hash = fnv_32_buf(ncp->nc_name, ncp->nc_nlen, FNV1_32_INIT);
1881 hash = fnv_32_buf(&ncp->nc_parent,
1882 sizeof(ncp->nc_parent), hash);
1883 nchpp = NCHHASH(hash);
1884 LIST_INSERT_HEAD(nchpp, ncp, nc_hash);
1885 ncp->nc_flag |= NCF_HASHED;
1890 * Name cache initialization, from vfsinit() when we are booting
1898 /* initialise per-cpu namecache effectiveness statistics. */
1899 for (i = 0; i < ncpus; ++i) {
1900 gd = globaldata_find(i);
1901 gd->gd_nchstats = &nchstats[i];
1903 TAILQ_INIT(&ncneglist);
1904 nchashtbl = hashinit(desiredvnodes*2, M_VFSCACHE, &nchash);
1905 nclockwarn = 1 * hz;
1909 * Called from start_init() to bootstrap the root filesystem. Returns
1910 * a referenced, unlocked namecache record.
1913 cache_allocroot(struct mount *mp, struct vnode *vp)
1915 struct namecache *ncp = cache_alloc(0);
1917 ncp->nc_flag |= NCF_MOUNTPT | NCF_ROOT;
1919 cache_setvp(ncp, vp);
1924 * vfs_cache_setroot()
1926 * Create an association between the root of our namecache and
1927 * the root vnode. This routine may be called several times during
1930 * If the caller intends to save the returned namecache pointer somewhere
1931 * it must cache_hold() it.
1934 vfs_cache_setroot(struct vnode *nvp, struct namecache *ncp)
1937 struct namecache *oncp;
1951 * XXX OLD API COMPAT FUNCTION. This really messes up the new namecache
1952 * topology and is being removed as quickly as possible. The new VOP_N*()
1953 * API calls are required to make specific adjustments using the supplied
1954 * ncp pointers rather then just bogusly purging random vnodes.
1956 * Invalidate all namecache entries to a particular vnode as well as
1957 * any direct children of that vnode in the namecache. This is a
1958 * 'catch all' purge used by filesystems that do not know any better.
1960 * Note that the linkage between the vnode and its namecache entries will
1961 * be removed, but the namecache entries themselves might stay put due to
1962 * active references from elsewhere in the system or due to the existance of
1963 * the children. The namecache topology is left intact even if we do not
1964 * know what the vnode association is. Such entries will be marked
1968 cache_purge(struct vnode *vp)
1970 cache_inval_vp(vp, CINV_DESTROY | CINV_CHILDREN);
1974 * Flush all entries referencing a particular filesystem.
1976 * Since we need to check it anyway, we will flush all the invalid
1977 * entries at the same time.
1980 cache_purgevfs(struct mount *mp)
1982 struct nchashhead *nchpp;
1983 struct namecache *ncp, *nnp;
1986 * Scan hash tables for applicable entries.
1988 for (nchpp = &nchashtbl[nchash]; nchpp >= nchashtbl; nchpp--) {
1989 ncp = LIST_FIRST(nchpp);
1993 nnp = LIST_NEXT(ncp, nc_hash);
1996 if (ncp->nc_mount == mp) {
2008 * Create a new (theoretically) unique fsmid
2011 cache_getnewfsmid(void)
2013 static int fsmid_roller;
2017 fsmid = ((int64_t)time_second << 32) |
2018 (fsmid_roller & 0x7FFFFFFF);
2023 static int disablecwd;
2024 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, "");
2026 static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls);
2027 static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1);
2028 static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2);
2029 static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3);
2030 static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4);
2031 static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound);
2034 sys___getcwd(struct __getcwd_args *uap)
2044 buflen = uap->buflen;
2047 if (buflen > MAXPATHLEN)
2048 buflen = MAXPATHLEN;
2050 buf = kmalloc(buflen, M_TEMP, M_WAITOK);
2051 bp = kern_getcwd(buf, buflen, &error);
2053 error = copyout(bp, uap->buf, strlen(bp) + 1);
2059 kern_getcwd(char *buf, size_t buflen, int *error)
2061 struct proc *p = curproc;
2063 int i, slash_prefixed;
2064 struct filedesc *fdp;
2065 struct namecache *ncp;
2074 ncp = fdp->fd_ncdir;
2075 while (ncp && ncp != fdp->fd_nrdir && (ncp->nc_flag & NCF_ROOT) == 0) {
2076 if (ncp->nc_flag & NCF_MOUNTPT) {
2077 if (ncp->nc_mount == NULL) {
2078 *error = EBADF; /* forced unmount? */
2081 ncp = ncp->nc_parent;
2084 for (i = ncp->nc_nlen - 1; i >= 0; i--) {
2090 *--bp = ncp->nc_name[i];
2099 ncp = ncp->nc_parent;
2106 if (!slash_prefixed) {
2120 * Thus begins the fullpath magic.
2124 #define STATNODE(name) \
2125 static u_int name; \
2126 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "")
2128 static int disablefullpath;
2129 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW,
2130 &disablefullpath, 0, "");
2132 STATNODE(numfullpathcalls);
2133 STATNODE(numfullpathfail1);
2134 STATNODE(numfullpathfail2);
2135 STATNODE(numfullpathfail3);
2136 STATNODE(numfullpathfail4);
2137 STATNODE(numfullpathfound);
2140 cache_fullpath(struct proc *p, struct namecache *ncp, char **retbuf, char **freebuf)
2143 int i, slash_prefixed;
2144 struct namecache *fd_nrdir;
2148 buf = kmalloc(MAXPATHLEN, M_TEMP, M_WAITOK);
2149 bp = buf + MAXPATHLEN - 1;
2152 fd_nrdir = p->p_fd->fd_nrdir;
2156 while (ncp && ncp != fd_nrdir && (ncp->nc_flag & NCF_ROOT) == 0) {
2157 if (ncp->nc_flag & NCF_MOUNTPT) {
2158 if (ncp->nc_mount == NULL) {
2162 ncp = ncp->nc_parent;
2165 for (i = ncp->nc_nlen - 1; i >= 0; i--) {
2171 *--bp = ncp->nc_name[i];
2180 ncp = ncp->nc_parent;
2187 if (p != NULL && (ncp->nc_flag & NCF_ROOT) && ncp != fd_nrdir) {
2188 bp = buf + MAXPATHLEN - 1;
2192 if (!slash_prefixed) {
2208 vn_fullpath(struct proc *p, struct vnode *vn, char **retbuf, char **freebuf)
2210 struct namecache *ncp;
2213 if (disablefullpath)
2219 /* vn is NULL, client wants us to use p->p_textvp */
2221 if ((vn = p->p_textvp) == NULL)
2224 TAILQ_FOREACH(ncp, &vn->v_namecache, nc_vnode) {
2232 return(cache_fullpath(p, ncp, retbuf, freebuf));