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.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
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
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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.
40 * Redistribution and use in source and binary forms, with or without
41 * modification, are permitted provided that the following conditions
43 * 1. Redistributions of source code must retain the above copyright
44 * notice, this list of conditions and the following disclaimer.
45 * 2. Redistributions in binary form must reproduce the above copyright
46 * notice, this list of conditions and the following disclaimer in the
47 * documentation and/or other materials provided with the distribution.
48 * 3. All advertising materials mentioning features or use of this software
49 * must display the following acknowledgement:
50 * This product includes software developed by the University of
51 * California, Berkeley and its contributors.
52 * 4. Neither the name of the University nor the names of its contributors
53 * may be used to endorse or promote products derived from this software
54 * without specific prior written permission.
56 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
57 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
58 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
59 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
60 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 1.57 2005/08/27 20:23:05 joerg 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 */
115 static int64_t last_fsmid; /* node change id */
118 * ncvp_debug - debug cache_fromvp(). This is used by the NFS server
119 * to create the namecache infrastructure leading to a dangling vnode.
121 * 0 Only errors are reported
122 * 1 Successes are reported
123 * 2 Successes + the whole directory scan is reported
124 * 3 Force the directory scan code run as if the parent vnode did not
125 * have a namecache record, even if it does have one.
127 static int ncvp_debug;
128 SYSCTL_INT(_debug, OID_AUTO, ncvp_debug, CTLFLAG_RW, &ncvp_debug, 0, "");
130 static u_long nchash; /* size of hash table */
131 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, "");
133 static u_long ncnegfactor = 16; /* ratio of negative entries */
134 SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, "");
136 static int nclockwarn; /* warn on locked entries in ticks */
137 SYSCTL_INT(_debug, OID_AUTO, nclockwarn, CTLFLAG_RW, &nclockwarn, 0, "");
139 static u_long numneg; /* number of cache entries allocated */
140 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, "");
142 static u_long numcache; /* number of cache entries allocated */
143 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, "");
145 static u_long numunres; /* number of unresolved entries */
146 SYSCTL_ULONG(_debug, OID_AUTO, numunres, CTLFLAG_RD, &numunres, 0, "");
148 SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode), "");
149 SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache), "");
151 static int cache_resolve_mp(struct namecache *ncp);
152 static void cache_rehash(struct namecache *ncp);
155 * The new name cache statistics
157 SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics");
158 #define STATNODE(mode, name, var) \
159 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, "");
160 STATNODE(CTLFLAG_RD, numneg, &numneg);
161 STATNODE(CTLFLAG_RD, numcache, &numcache);
162 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls);
163 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits);
164 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits);
165 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks);
166 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss);
167 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap);
168 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps);
169 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits);
170 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps);
171 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits);
173 struct nchstats nchstats[SMP_MAXCPU];
175 * Export VFS cache effectiveness statistics to user-land.
177 * The statistics are left for aggregation to user-land so
178 * neat things can be achieved, like observing per-CPU cache
182 sysctl_nchstats(SYSCTL_HANDLER_ARGS)
184 struct globaldata *gd;
188 for (i = 0; i < ncpus; ++i) {
189 gd = globaldata_find(i);
190 if ((error = SYSCTL_OUT(req, (void *)&(*gd->gd_nchstats),
191 sizeof(struct nchstats))))
197 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE|CTLFLAG_RD,
198 0, 0, sysctl_nchstats, "S,nchstats", "VFS cache effectiveness statistics");
200 static void cache_zap(struct namecache *ncp);
203 * cache_hold() and cache_drop() prevent the premature deletion of a
204 * namecache entry but do not prevent operations (such as zapping) on
205 * that namecache entry.
209 _cache_hold(struct namecache *ncp)
216 * When dropping an entry, if only one ref remains and the entry has not
217 * been resolved, zap it. Since the one reference is being dropped the
218 * entry had better not be locked.
222 _cache_drop(struct namecache *ncp)
224 KKASSERT(ncp->nc_refs > 0);
225 if (ncp->nc_refs == 1 &&
226 (ncp->nc_flag & NCF_UNRESOLVED) &&
227 TAILQ_EMPTY(&ncp->nc_list)
229 KKASSERT(ncp->nc_exlocks == 0);
238 * Link a new namecache entry to its parent. Be careful to avoid races
239 * if vhold() blocks in the future.
241 * If we are creating a child under an oldapi parent we must mark the
242 * child as being an oldapi entry as well.
245 cache_link_parent(struct namecache *ncp, struct namecache *par)
247 KKASSERT(ncp->nc_parent == NULL);
248 ncp->nc_parent = par;
249 if (TAILQ_EMPTY(&par->nc_list)) {
250 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry);
252 * Any vp associated with an ncp which has children must
253 * be held to prevent it from being recycled.
258 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry);
263 * Remove the parent association from a namecache structure. If this is
264 * the last child of the parent the cache_drop(par) will attempt to
265 * recursively zap the parent.
268 cache_unlink_parent(struct namecache *ncp)
270 struct namecache *par;
272 if ((par = ncp->nc_parent) != NULL) {
273 ncp->nc_parent = NULL;
274 par = cache_hold(par);
275 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry);
276 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list))
283 * Allocate a new namecache structure. Most of the code does not require
284 * zero-termination of the string but it makes vop_compat_ncreate() easier.
286 static struct namecache *
287 cache_alloc(int nlen)
289 struct namecache *ncp;
291 ncp = malloc(sizeof(*ncp), M_VFSCACHE, M_WAITOK|M_ZERO);
293 ncp->nc_name = malloc(nlen + 1, M_VFSCACHE, M_WAITOK);
295 ncp->nc_flag = NCF_UNRESOLVED;
296 ncp->nc_error = ENOTCONN; /* needs to be resolved */
298 ncp->nc_fsmid = ++last_fsmid;
299 TAILQ_INIT(&ncp->nc_list);
305 cache_free(struct namecache *ncp)
307 KKASSERT(ncp->nc_refs == 1 && ncp->nc_exlocks == 1);
309 free(ncp->nc_name, M_VFSCACHE);
310 free(ncp, M_VFSCACHE);
314 * Ref and deref a namecache structure.
317 cache_hold(struct namecache *ncp)
319 return(_cache_hold(ncp));
323 cache_drop(struct namecache *ncp)
329 * Namespace locking. The caller must already hold a reference to the
330 * namecache structure in order to lock/unlock it. This function prevents
331 * the namespace from being created or destroyed by accessors other then
334 * Note that holding a locked namecache structure prevents other threads
335 * from making namespace changes (e.g. deleting or creating), prevents
336 * vnode association state changes by other threads, and prevents the
337 * namecache entry from being resolved or unresolved by other threads.
339 * The lock owner has full authority to associate/disassociate vnodes
340 * and resolve/unresolve the locked ncp.
342 * In particular, if a vnode is associated with a locked cache entry
343 * that vnode will *NOT* be recycled. We accomplish this by vhold()ing the
344 * vnode. XXX we should find a more efficient way to prevent the vnode
345 * from being recycled, but remember that any given vnode may have multiple
346 * namecache associations (think hardlinks).
349 cache_lock(struct namecache *ncp)
354 KKASSERT(ncp->nc_refs != 0);
359 if (ncp->nc_exlocks == 0) {
363 * The vp associated with a locked ncp must be held
364 * to prevent it from being recycled (which would
365 * cause the ncp to become unresolved).
367 * XXX loop on race for later MPSAFE work.
373 if (ncp->nc_locktd == td) {
377 ncp->nc_flag |= NCF_LOCKREQ;
378 if (tsleep(ncp, 0, "clock", nclockwarn) == EWOULDBLOCK) {
382 printf("[diagnostic] cache_lock: blocked on %p", ncp);
383 if ((ncp->nc_flag & NCF_MOUNTPT) && ncp->nc_mount)
384 printf(" [MOUNTFROM %s]\n", ncp->nc_mount->mnt_stat.f_mntfromname);
386 printf(" \"%*.*s\"\n",
387 ncp->nc_nlen, ncp->nc_nlen,
393 printf("[diagnostic] cache_lock: unblocked %*.*s\n",
394 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name);
399 cache_lock_nonblock(struct namecache *ncp)
403 KKASSERT(ncp->nc_refs != 0);
405 if (ncp->nc_exlocks == 0) {
409 * The vp associated with a locked ncp must be held
410 * to prevent it from being recycled (which would
411 * cause the ncp to become unresolved).
413 * XXX loop on race for later MPSAFE work.
424 cache_unlock(struct namecache *ncp)
426 thread_t td = curthread;
428 KKASSERT(ncp->nc_refs > 0);
429 KKASSERT(ncp->nc_exlocks > 0);
430 KKASSERT(ncp->nc_locktd == td);
431 if (--ncp->nc_exlocks == 0) {
434 ncp->nc_locktd = NULL;
435 if (ncp->nc_flag & NCF_LOCKREQ) {
436 ncp->nc_flag &= ~NCF_LOCKREQ;
443 * ref-and-lock, unlock-and-deref functions.
446 cache_get(struct namecache *ncp)
454 cache_get_nonblock(struct namecache *ncp)
457 if (ncp->nc_exlocks == 0 || ncp->nc_locktd == curthread) {
466 cache_put(struct namecache *ncp)
473 * Resolve an unresolved ncp by associating a vnode with it. If the
474 * vnode is NULL, a negative cache entry is created.
476 * The ncp should be locked on entry and will remain locked on return.
479 cache_setvp(struct namecache *ncp, struct vnode *vp)
481 KKASSERT(ncp->nc_flag & NCF_UNRESOLVED);
485 * Any vp associated with an ncp which has children must
486 * be held. Any vp associated with a locked ncp must be held.
488 if (!TAILQ_EMPTY(&ncp->nc_list))
490 TAILQ_INSERT_HEAD(&vp->v_namecache, ncp, nc_vnode);
495 * Set auxillary flags
499 ncp->nc_flag |= NCF_ISDIR;
502 ncp->nc_flag |= NCF_ISSYMLINK;
503 /* XXX cache the contents of the symlink */
511 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode);
513 ncp->nc_error = ENOENT;
515 ncp->nc_flag &= ~NCF_UNRESOLVED;
519 cache_settimeout(struct namecache *ncp, int nticks)
521 if ((ncp->nc_timeout = ticks + nticks) == 0)
526 * Disassociate the vnode or negative-cache association and mark a
527 * namecache entry as unresolved again. Note that the ncp is still
528 * left in the hash table and still linked to its parent.
530 * The ncp should be locked and refd on entry and will remain locked and refd
533 * This routine is normally never called on a directory containing children.
534 * However, NFS often does just that in its rename() code as a cop-out to
535 * avoid complex namespace operations. This disconnects a directory vnode
536 * from its namecache and can cause the OLDAPI and NEWAPI to get out of
540 cache_setunresolved(struct namecache *ncp)
544 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
545 ncp->nc_flag |= NCF_UNRESOLVED;
546 ncp->nc_flag &= ~(NCF_WHITEOUT|NCF_ISDIR|NCF_ISSYMLINK);
548 ncp->nc_error = ENOTCONN;
550 if ((vp = ncp->nc_vp) != NULL) {
553 TAILQ_REMOVE(&vp->v_namecache, ncp, nc_vnode);
556 * Any vp associated with an ncp with children is
557 * held by that ncp. Any vp associated with a locked
558 * ncp is held by that ncp. These conditions must be
559 * undone when the vp is cleared out from the ncp.
561 if (!TAILQ_EMPTY(&ncp->nc_list))
566 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode);
573 * Invalidate portions of the namecache topology given a starting entry.
574 * The passed ncp is set to an unresolved state and:
576 * The passed ncp must be locked.
578 * CINV_DESTROY - Set a flag in the passed ncp entry indicating
579 * that the physical underlying nodes have been
580 * destroyed... as in deleted. For example, when
581 * a directory is removed. This will cause record
582 * lookups on the name to no longer be able to find
583 * the record and tells the resolver to return failure
584 * rather then trying to resolve through the parent.
586 * The topology itself, including ncp->nc_name,
589 * This only applies to the passed ncp, if CINV_CHILDREN
590 * is specified the children are not flagged.
592 * CINV_CHILDREN - Set all children (recursively) to an unresolved
595 * Note that this will also have the side effect of
596 * cleaning out any unreferenced nodes in the topology
597 * from the leaves up as the recursion backs out.
599 * Note that the topology for any referenced nodes remains intact.
601 * It is possible for cache_inval() to race a cache_resolve(), meaning that
602 * the namecache entry may not actually be invalidated on return if it was
603 * revalidated while recursing down into its children. This code guarentees
604 * that the node(s) will go through an invalidation cycle, but does not
605 * guarentee that they will remain in an invalidated state.
607 * Returns non-zero if a revalidation was detected during the invalidation
608 * recursion, zero otherwise. Note that since only the original ncp is
609 * locked the revalidation ultimately can only indicate that the original ncp
610 * *MIGHT* no have been reresolved.
613 cache_inval(struct namecache *ncp, int flags)
615 struct namecache *kid;
616 struct namecache *nextkid;
619 KKASSERT(ncp->nc_exlocks);
621 cache_setunresolved(ncp);
622 if (flags & CINV_DESTROY)
623 ncp->nc_flag |= NCF_DESTROYED;
625 if ((flags & CINV_CHILDREN) &&
626 (kid = TAILQ_FIRST(&ncp->nc_list)) != NULL
631 if ((nextkid = TAILQ_NEXT(kid, nc_entry)) != NULL)
633 if ((kid->nc_flag & NCF_UNRESOLVED) == 0 ||
634 TAILQ_FIRST(&kid->nc_list)
637 rcnt += cache_inval(kid, flags & ~CINV_DESTROY);
647 * Someone could have gotten in there while ncp was unlocked,
650 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0)
656 * Invalidate a vnode's namecache associations. To avoid races against
657 * the resolver we do not invalidate a node which we previously invalidated
658 * but which was then re-resolved while we were in the invalidation loop.
660 * Returns non-zero if any namecache entries remain after the invalidation
663 * NOTE: unlike the namecache topology which guarentees that ncp's will not
664 * be ripped out of the topology while held, the vnode's v_namecache list
665 * has no such restriction. NCP's can be ripped out of the list at virtually
666 * any time if not locked, even if held.
669 cache_inval_vp(struct vnode *vp, int flags)
671 struct namecache *ncp;
672 struct namecache *next;
675 ncp = TAILQ_FIRST(&vp->v_namecache);
679 /* loop entered with ncp held */
680 if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL)
683 if (ncp->nc_vp != vp) {
684 printf("Warning: cache_inval_vp: race-A detected on "
685 "%s\n", ncp->nc_name);
691 cache_inval(ncp, flags);
692 cache_put(ncp); /* also releases reference */
694 if (ncp && ncp->nc_vp != vp) {
695 printf("Warning: cache_inval_vp: race-B detected on "
696 "%s\n", ncp->nc_name);
701 return(TAILQ_FIRST(&vp->v_namecache) != NULL);
705 * The source ncp has been renamed to the target ncp. Both fncp and tncp
706 * must be locked. Both will be set to unresolved, any children of tncp
707 * will be disconnected (the prior contents of the target is assumed to be
708 * destroyed by the rename operation, e.g. renaming over an empty directory),
709 * and all children of fncp will be moved to tncp.
711 * XXX the disconnection could pose a problem, check code paths to make
712 * sure any code that blocks can handle the parent being changed out from
713 * under it. Maybe we should lock the children (watch out for deadlocks) ?
715 * After we return the caller has the option of calling cache_setvp() if
716 * the vnode of the new target ncp is known.
718 * Any process CD'd into any of the children will no longer be able to ".."
719 * back out. An rm -rf can cause this situation to occur.
722 cache_rename(struct namecache *fncp, struct namecache *tncp)
724 struct namecache *scan;
727 cache_setunresolved(fncp);
728 cache_setunresolved(tncp);
729 while (cache_inval(tncp, CINV_CHILDREN) != 0) {
730 if (didwarn++ % 10 == 0) {
731 printf("Warning: cache_rename: race during "
733 fncp->nc_name, tncp->nc_name);
735 tsleep(tncp, 0, "mvrace", hz / 10);
736 cache_setunresolved(tncp);
738 while ((scan = TAILQ_FIRST(&fncp->nc_list)) != NULL) {
740 cache_unlink_parent(scan);
741 cache_link_parent(scan, tncp);
742 if (scan->nc_flag & NCF_HASHED)
749 * vget the vnode associated with the namecache entry. Resolve the namecache
750 * entry if necessary and deal with namecache/vp races. The passed ncp must
751 * be referenced and may be locked. The ncp's ref/locking state is not
752 * effected by this call.
754 * lk_type may be LK_SHARED, LK_EXCLUSIVE. A ref'd, possibly locked
755 * (depending on the passed lk_type) will be returned in *vpp with an error
756 * of 0, or NULL will be returned in *vpp with a non-0 error code. The
757 * most typical error is ENOENT, meaning that the ncp represents a negative
758 * cache hit and there is no vnode to retrieve, but other errors can occur
761 * The main race we have to deal with are namecache zaps. The ncp itself
762 * will not disappear since it is referenced, and it turns out that the
763 * validity of the vp pointer can be checked simply by rechecking the
764 * contents of ncp->nc_vp.
767 cache_vget(struct namecache *ncp, struct ucred *cred,
768 int lk_type, struct vnode **vpp)
775 if (ncp->nc_flag & NCF_UNRESOLVED) {
777 error = cache_resolve(ncp, cred);
782 if (error == 0 && (vp = ncp->nc_vp) != NULL) {
783 error = vget(vp, lk_type, curthread);
785 if (vp != ncp->nc_vp) /* handle cache_zap race */
788 } else if (vp != ncp->nc_vp) { /* handle cache_zap race */
793 if (error == 0 && vp == NULL)
800 cache_vref(struct namecache *ncp, struct ucred *cred, struct vnode **vpp)
807 if (ncp->nc_flag & NCF_UNRESOLVED) {
809 error = cache_resolve(ncp, cred);
814 if (error == 0 && (vp = ncp->nc_vp) != NULL) {
816 if (vp != ncp->nc_vp) { /* handle cache_zap race */
821 if (error == 0 && vp == NULL)
828 cache_update_fsmid(struct namecache *ncp)
831 struct namecache *scan;
832 int64_t fsmid = ++last_fsmid;
834 if ((vp = ncp->nc_vp) != NULL) {
835 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
836 for (scan = ncp; scan; scan = scan->nc_parent)
837 scan->nc_fsmid = fsmid;
841 ncp->nc_fsmid = fsmid;
842 ncp = ncp->nc_parent;
848 cache_update_fsmid_vp(struct vnode *vp)
850 struct namecache *ncp;
851 struct namecache *scan;
852 int64_t fsmid = ++last_fsmid;
854 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
855 for (scan = ncp; scan; scan = scan->nc_parent)
856 scan->nc_fsmid = fsmid;
861 * Convert a directory vnode to a namecache record without any other
862 * knowledge of the topology. This ONLY works with directory vnodes and
863 * is ONLY used by the NFS server. dvp must be refd but unlocked, and the
864 * returned ncp (if not NULL) will be held and unlocked.
866 * If 'makeit' is 0 and dvp has no existing namecache record, NULL is returned.
867 * If 'makeit' is 1 we attempt to track-down and create the namecache topology
868 * for dvp. This will fail only if the directory has been deleted out from
871 * Callers must always check for a NULL return no matter the value of 'makeit'.
874 static int cache_inefficient_scan(struct namecache *ncp, struct ucred *cred,
878 cache_fromdvp(struct vnode *dvp, struct ucred *cred, int makeit)
880 struct namecache *ncp;
885 * Temporary debugging code to force the directory scanning code
889 if (ncvp_debug >= 3 && makeit && TAILQ_FIRST(&dvp->v_namecache)) {
890 ncp = TAILQ_FIRST(&dvp->v_namecache);
891 printf("cache_fromdvp: forcing %s\n", ncp->nc_name);
896 * Loop until resolution, inside code will break out on error.
898 while ((ncp = TAILQ_FIRST(&dvp->v_namecache)) == NULL && makeit) {
901 * If dvp is the root of its filesystem it should already
902 * have a namecache pointer associated with it as a side
903 * effect of the mount, but it may have been disassociated.
905 if (dvp->v_flag & VROOT) {
906 ncp = cache_get(dvp->v_mount->mnt_ncp);
907 error = cache_resolve_mp(ncp);
910 printf("cache_fromdvp: resolve root of mount %p error %d",
911 dvp->v_mount, error);
920 printf(" succeeded\n");
925 * Get the parent directory and resolve its ncp.
927 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred);
929 printf("lookupdotdot failed %d %p\n", error, pvp);
932 VOP_UNLOCK(pvp, 0, curthread);
935 * XXX this recursion could run the kernel out of stack,
936 * change to a less efficient algorithm if we get too deep
937 * (use 'makeit' for a depth counter?)
939 ncp = cache_fromdvp(pvp, cred, makeit);
945 * Do an inefficient scan of pvp (embodied by ncp) to look
946 * for dvp. This will create a namecache record for dvp on
947 * success. We loop up to recheck on success.
949 * ncp and dvp are both held but not locked.
951 error = cache_inefficient_scan(ncp, cred, dvp);
954 printf("cache_fromdvp: scan %p (%s) failed on dvp=%p\n",
955 pvp, ncp->nc_name, dvp);
960 printf("cache_fromdvp: scan %p (%s) succeeded\n",
970 * Do an inefficient scan of the directory represented by ncp looking for
971 * the directory vnode dvp. ncp must be held but not locked on entry and
972 * will be held on return. dvp must be refd but not locked on entry and
973 * will remain refd on return.
975 * Why do this at all? Well, due to its stateless nature the NFS server
976 * converts file handles directly to vnodes without necessarily going through
977 * the namecache ops that would otherwise create the namecache topology
978 * leading to the vnode. We could either (1) Change the namecache algorithms
979 * to allow disconnect namecache records that are re-merged opportunistically,
980 * or (2) Make the NFS server backtrack and scan to recover a connected
981 * namecache topology in order to then be able to issue new API lookups.
983 * It turns out that (1) is a huge mess. It takes a nice clean set of
984 * namecache algorithms and introduces a lot of complication in every subsystem
985 * that calls into the namecache to deal with the re-merge case, especially
986 * since we are using the namecache to placehold negative lookups and the
987 * vnode might not be immediately assigned. (2) is certainly far less
988 * efficient then (1), but since we are only talking about directories here
989 * (which are likely to remain cached), the case does not actually run all
990 * that often and has the supreme advantage of not polluting the namecache
994 cache_inefficient_scan(struct namecache *ncp, struct ucred *cred,
997 struct nlcomponent nlc;
998 struct namecache *rncp;
1010 vat.va_blocksize = 0;
1011 if ((error = VOP_GETATTR(dvp, &vat, curthread)) != 0)
1013 if ((error = cache_vget(ncp, cred, LK_SHARED, &pvp)) != 0)
1016 printf("inefficient_scan: directory iosize %ld vattr fileid = %ld\n", vat.va_blocksize, (long)vat.va_fileid);
1017 if ((blksize = vat.va_blocksize) == 0)
1018 blksize = DEV_BSIZE;
1019 rbuf = malloc(blksize, M_TEMP, M_WAITOK);
1025 iov.iov_base = rbuf;
1026 iov.iov_len = blksize;
1029 uio.uio_resid = blksize;
1030 uio.uio_segflg = UIO_SYSSPACE;
1031 uio.uio_rw = UIO_READ;
1032 uio.uio_td = curthread;
1034 if (ncvp_debug >= 2)
1035 printf("cache_inefficient_scan: readdir @ %08x\n", (int)uio.uio_offset);
1036 error = VOP_READDIR(pvp, &uio, cred, &eofflag, NULL, NULL);
1038 den = (struct dirent *)rbuf;
1039 bytes = blksize - uio.uio_resid;
1042 if (ncvp_debug >= 2) {
1043 printf("cache_inefficient_scan: %*.*s\n",
1044 den->d_namlen, den->d_namlen,
1047 if (den->d_type != DT_WHT &&
1048 den->d_ino == vat.va_fileid) {
1050 printf("cache_inefficient_scan: "
1051 "MATCHED inode %ld path %s/%*.*s\n",
1052 vat.va_fileid, ncp->nc_name,
1053 den->d_namlen, den->d_namlen,
1056 nlc.nlc_nameptr = den->d_name;
1057 nlc.nlc_namelen = den->d_namlen;
1058 VOP_UNLOCK(pvp, 0, curthread);
1059 rncp = cache_nlookup(ncp, &nlc);
1060 KKASSERT(rncp != NULL);
1063 bytes -= _DIRENT_DIRSIZ(den);
1064 den = _DIRENT_NEXT(den);
1066 if (rncp == NULL && eofflag == 0 && uio.uio_resid != blksize)
1071 if (rncp->nc_flag & NCF_UNRESOLVED) {
1072 cache_setvp(rncp, dvp);
1073 if (ncvp_debug >= 2) {
1074 printf("cache_inefficient_scan: setvp %s/%s = %p\n",
1075 ncp->nc_name, rncp->nc_name, dvp);
1078 if (ncvp_debug >= 2) {
1079 printf("cache_inefficient_scan: setvp %s/%s already set %p/%p\n",
1080 ncp->nc_name, rncp->nc_name, dvp,
1084 if (rncp->nc_vp == NULL)
1085 error = rncp->nc_error;
1088 printf("cache_inefficient_scan: dvp %p NOT FOUND in %s\n",
1098 * Zap a namecache entry. The ncp is unconditionally set to an unresolved
1099 * state, which disassociates it from its vnode or ncneglist.
1101 * Then, if there are no additional references to the ncp and no children,
1102 * the ncp is removed from the topology and destroyed. This function will
1103 * also run through the nc_parent chain and destroy parent ncps if possible.
1104 * As a side benefit, it turns out the only conditions that allow running
1105 * up the chain are also the conditions to ensure no deadlock will occur.
1107 * References and/or children may exist if the ncp is in the middle of the
1108 * topology, preventing the ncp from being destroyed.
1110 * This function must be called with the ncp held and locked and will unlock
1111 * and drop it during zapping.
1114 cache_zap(struct namecache *ncp)
1116 struct namecache *par;
1119 * Disassociate the vnode or negative cache ref and set NCF_UNRESOLVED.
1121 cache_setunresolved(ncp);
1124 * Try to scrap the entry and possibly tail-recurse on its parent.
1125 * We only scrap unref'd (other then our ref) unresolved entries,
1126 * we do not scrap 'live' entries.
1128 while (ncp->nc_flag & NCF_UNRESOLVED) {
1130 * Someone other then us has a ref, stop.
1132 if (ncp->nc_refs > 1)
1136 * We have children, stop.
1138 if (!TAILQ_EMPTY(&ncp->nc_list))
1142 * Remove ncp from the topology: hash table and parent linkage.
1144 if (ncp->nc_flag & NCF_HASHED) {
1145 ncp->nc_flag &= ~NCF_HASHED;
1146 LIST_REMOVE(ncp, nc_hash);
1148 if ((par = ncp->nc_parent) != NULL) {
1149 par = cache_hold(par);
1150 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry);
1151 ncp->nc_parent = NULL;
1152 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list))
1157 * ncp should not have picked up any refs. Physically
1160 KKASSERT(ncp->nc_refs == 1);
1162 /* cache_unlock(ncp) not required */
1163 ncp->nc_refs = -1; /* safety */
1165 free(ncp->nc_name, M_VFSCACHE);
1166 free(ncp, M_VFSCACHE);
1169 * Loop on the parent (it may be NULL). Only bother looping
1170 * if the parent has a single ref (ours), which also means
1171 * we can lock it trivially.
1176 if (ncp->nc_refs != 1) {
1180 KKASSERT(par->nc_exlocks == 0);
1188 static enum { CHI_LOW, CHI_HIGH } cache_hysteresis_state = CHI_LOW;
1192 cache_hysteresis(void)
1195 * Don't cache too many negative hits. We use hysteresis to reduce
1196 * the impact on the critical path.
1198 switch(cache_hysteresis_state) {
1200 if (numneg > MINNEG && numneg * ncnegfactor > numcache) {
1202 cache_hysteresis_state = CHI_HIGH;
1206 if (numneg > MINNEG * 9 / 10 &&
1207 numneg * ncnegfactor * 9 / 10 > numcache
1211 cache_hysteresis_state = CHI_LOW;
1218 * NEW NAMECACHE LOOKUP API
1220 * Lookup an entry in the cache. A locked, referenced, non-NULL
1221 * entry is *always* returned, even if the supplied component is illegal.
1222 * The resulting namecache entry should be returned to the system with
1223 * cache_put() or cache_unlock() + cache_drop().
1225 * namecache locks are recursive but care must be taken to avoid lock order
1228 * Nobody else will be able to manipulate the associated namespace (e.g.
1229 * create, delete, rename, rename-target) until the caller unlocks the
1232 * The returned entry will be in one of three states: positive hit (non-null
1233 * vnode), negative hit (null vnode), or unresolved (NCF_UNRESOLVED is set).
1234 * Unresolved entries must be resolved through the filesystem to associate the
1235 * vnode and/or determine whether a positive or negative hit has occured.
1237 * It is not necessary to lock a directory in order to lock namespace under
1238 * that directory. In fact, it is explicitly not allowed to do that. A
1239 * directory is typically only locked when being created, renamed, or
1242 * The directory (par) may be unresolved, in which case any returned child
1243 * will likely also be marked unresolved. Likely but not guarenteed. Since
1244 * the filesystem lookup requires a resolved directory vnode the caller is
1245 * responsible for resolving the namecache chain top-down. This API
1246 * specifically allows whole chains to be created in an unresolved state.
1249 cache_nlookup(struct namecache *par, struct nlcomponent *nlc)
1251 struct namecache *ncp;
1252 struct namecache *new_ncp;
1253 struct nchashhead *nchpp;
1261 * Try to locate an existing entry
1263 hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT);
1264 hash = fnv_32_buf(&par, sizeof(par), hash);
1267 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
1271 * Zap entries that have timed out.
1273 if (ncp->nc_timeout &&
1274 (int)(ncp->nc_timeout - ticks) < 0 &&
1275 (ncp->nc_flag & NCF_UNRESOLVED) == 0 &&
1276 ncp->nc_exlocks == 0
1278 cache_zap(cache_get(ncp));
1283 * Break out if we find a matching entry. Note that
1284 * UNRESOLVED entries may match, but DESTROYED entries
1287 if (ncp->nc_parent == par &&
1288 ncp->nc_nlen == nlc->nlc_namelen &&
1289 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 &&
1290 (ncp->nc_flag & NCF_DESTROYED) == 0
1292 if (cache_get_nonblock(ncp) == 0) {
1294 cache_free(new_ncp);
1304 * We failed to locate an entry, create a new entry and add it to
1305 * the cache. We have to relookup after possibly blocking in
1308 if (new_ncp == NULL) {
1309 new_ncp = cache_alloc(nlc->nlc_namelen);
1316 * Initialize as a new UNRESOLVED entry, lock (non-blocking),
1317 * and link to the parent. The mount point is usually inherited
1318 * from the parent unless this is a special case such as a mount
1319 * point where nlc_namelen is 0. The caller is responsible for
1320 * setting nc_mount in that case. If nlc_namelen is 0 nc_name will
1323 if (nlc->nlc_namelen) {
1324 bcopy(nlc->nlc_nameptr, ncp->nc_name, nlc->nlc_namelen);
1325 ncp->nc_name[nlc->nlc_namelen] = 0;
1326 ncp->nc_mount = par->nc_mount;
1328 nchpp = NCHHASH(hash);
1329 LIST_INSERT_HEAD(nchpp, ncp, nc_hash);
1330 ncp->nc_flag |= NCF_HASHED;
1331 cache_link_parent(ncp, par);
1334 * stats and namecache size management
1336 if (ncp->nc_flag & NCF_UNRESOLVED)
1337 ++gd->gd_nchstats->ncs_miss;
1338 else if (ncp->nc_vp)
1339 ++gd->gd_nchstats->ncs_goodhits;
1341 ++gd->gd_nchstats->ncs_neghits;
1347 * Resolve an unresolved namecache entry, generally by looking it up.
1348 * The passed ncp must be locked and refd.
1350 * Theoretically since a vnode cannot be recycled while held, and since
1351 * the nc_parent chain holds its vnode as long as children exist, the
1352 * direct parent of the cache entry we are trying to resolve should
1353 * have a valid vnode. If not then generate an error that we can
1354 * determine is related to a resolver bug.
1356 * Note that successful resolution does not necessarily return an error
1357 * code of 0. If the ncp resolves to a negative cache hit then ENOENT
1361 cache_resolve(struct namecache *ncp, struct ucred *cred)
1363 struct namecache *par;
1368 * If the ncp is already resolved we have nothing to do.
1370 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0)
1371 return (ncp->nc_error);
1374 * Mount points need special handling because the parent does not
1375 * belong to the same filesystem as the ncp.
1377 if (ncp->nc_flag & NCF_MOUNTPT)
1378 return (cache_resolve_mp(ncp));
1381 * We expect an unbroken chain of ncps to at least the mount point,
1382 * and even all the way to root (but this code doesn't have to go
1383 * past the mount point).
1385 if (ncp->nc_parent == NULL) {
1386 printf("EXDEV case 1 %p %*.*s\n", ncp,
1387 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name);
1388 ncp->nc_error = EXDEV;
1389 return(ncp->nc_error);
1393 * The vp's of the parent directories in the chain are held via vhold()
1394 * due to the existance of the child, and should not disappear.
1395 * However, there are cases where they can disappear:
1397 * - due to filesystem I/O errors.
1398 * - due to NFS being stupid about tracking the namespace and
1399 * destroys the namespace for entire directories quite often.
1400 * - due to forced unmounts.
1401 * - due to an rmdir (parent will be marked DESTROYED)
1403 * When this occurs we have to track the chain backwards and resolve
1404 * it, looping until the resolver catches up to the current node. We
1405 * could recurse here but we might run ourselves out of kernel stack
1406 * so we do it in a more painful manner. This situation really should
1407 * not occur all that often, or if it does not have to go back too
1408 * many nodes to resolve the ncp.
1410 while (ncp->nc_parent->nc_vp == NULL) {
1412 * This case can occur if a process is CD'd into a
1413 * directory which is then rmdir'd. If the parent is marked
1414 * destroyed there is no point trying to resolve it.
1416 if (ncp->nc_parent->nc_flag & NCF_DESTROYED)
1419 par = ncp->nc_parent;
1420 while (par->nc_parent && par->nc_parent->nc_vp == NULL)
1421 par = par->nc_parent;
1422 if (par->nc_parent == NULL) {
1423 printf("EXDEV case 2 %*.*s\n",
1424 par->nc_nlen, par->nc_nlen, par->nc_name);
1427 printf("[diagnostic] cache_resolve: had to recurse on %*.*s\n",
1428 par->nc_nlen, par->nc_nlen, par->nc_name);
1430 * The parent is not set in stone, ref and lock it to prevent
1431 * it from disappearing. Also note that due to renames it
1432 * is possible for our ncp to move and for par to no longer
1433 * be one of its parents. We resolve it anyway, the loop
1434 * will handle any moves.
1437 if (par->nc_flag & NCF_MOUNTPT) {
1438 cache_resolve_mp(par);
1439 } else if (par->nc_parent->nc_vp == NULL) {
1440 printf("[diagnostic] cache_resolve: raced on %*.*s\n", par->nc_nlen, par->nc_nlen, par->nc_name);
1443 } else if (par->nc_flag & NCF_UNRESOLVED) {
1444 par->nc_error = VOP_NRESOLVE(par, cred);
1446 if ((error = par->nc_error) != 0) {
1447 if (par->nc_error != EAGAIN) {
1448 printf("EXDEV case 3 %*.*s error %d\n",
1449 par->nc_nlen, par->nc_nlen, par->nc_name,
1454 printf("[diagnostic] cache_resolve: EAGAIN par %p %*.*s\n",
1455 par, par->nc_nlen, par->nc_nlen, par->nc_name);
1462 * Call VOP_NRESOLVE() to get the vp, then scan for any disconnected
1463 * ncp's and reattach them. If this occurs the original ncp is marked
1464 * EAGAIN to force a relookup.
1466 * NOTE: in order to call VOP_NRESOLVE(), the parent of the passed
1467 * ncp must already be resolved.
1469 KKASSERT((ncp->nc_flag & NCF_MOUNTPT) == 0);
1470 ncp->nc_error = VOP_NRESOLVE(ncp, cred);
1471 /*vop_nresolve(*ncp->nc_parent->nc_vp->v_ops, ncp, cred);*/
1472 if (ncp->nc_error == EAGAIN) {
1473 printf("[diagnostic] cache_resolve: EAGAIN ncp %p %*.*s\n",
1474 ncp, ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name);
1477 return(ncp->nc_error);
1481 * Resolve the ncp associated with a mount point. Such ncp's almost always
1482 * remain resolved and this routine is rarely called. NFS MPs tends to force
1483 * re-resolution more often due to its mac-truck-smash-the-namecache
1484 * method of tracking namespace changes.
1486 * The semantics for this call is that the passed ncp must be locked on
1487 * entry and will be locked on return. However, if we actually have to
1488 * resolve the mount point we temporarily unlock the entry in order to
1489 * avoid race-to-root deadlocks due to e.g. dead NFS mounts. Because of
1490 * the unlock we have to recheck the flags after we relock.
1493 cache_resolve_mp(struct namecache *ncp)
1496 struct mount *mp = ncp->nc_mount;
1499 KKASSERT(mp != NULL);
1500 if (ncp->nc_flag & NCF_UNRESOLVED) {
1502 while (vfs_busy(mp, 0, curthread))
1504 error = VFS_ROOT(mp, &vp);
1508 * recheck the ncp state after relocking.
1510 if (ncp->nc_flag & NCF_UNRESOLVED) {
1511 ncp->nc_error = error;
1513 cache_setvp(ncp, vp);
1516 printf("[diagnostic] cache_resolve_mp: failed to resolve mount %p\n", mp);
1517 cache_setvp(ncp, NULL);
1519 } else if (error == 0) {
1522 vfs_unbusy(mp, curthread);
1524 return(ncp->nc_error);
1528 cache_cleanneg(int count)
1530 struct namecache *ncp;
1533 * Automode from the vnlru proc - clean out 10% of the negative cache
1537 count = numneg / 10 + 1;
1540 * Attempt to clean out the specified number of negative cache
1544 ncp = TAILQ_FIRST(&ncneglist);
1546 KKASSERT(numneg == 0);
1549 TAILQ_REMOVE(&ncneglist, ncp, nc_vnode);
1550 TAILQ_INSERT_TAIL(&ncneglist, ncp, nc_vnode);
1551 if (cache_get_nonblock(ncp) == 0)
1558 * Rehash a ncp. Rehashing is typically required if the name changes (should
1559 * not generally occur) or the parent link changes. This function will
1560 * unhash the ncp if the ncp is no longer hashable.
1563 cache_rehash(struct namecache *ncp)
1565 struct nchashhead *nchpp;
1568 if (ncp->nc_flag & NCF_HASHED) {
1569 ncp->nc_flag &= ~NCF_HASHED;
1570 LIST_REMOVE(ncp, nc_hash);
1572 if (ncp->nc_nlen && ncp->nc_parent) {
1573 hash = fnv_32_buf(ncp->nc_name, ncp->nc_nlen, FNV1_32_INIT);
1574 hash = fnv_32_buf(&ncp->nc_parent,
1575 sizeof(ncp->nc_parent), hash);
1576 nchpp = NCHHASH(hash);
1577 LIST_INSERT_HEAD(nchpp, ncp, nc_hash);
1578 ncp->nc_flag |= NCF_HASHED;
1583 * Name cache initialization, from vfsinit() when we are booting
1591 /* initialise per-cpu namecache effectiveness statistics. */
1592 for (i = 0; i < ncpus; ++i) {
1593 gd = globaldata_find(i);
1594 gd->gd_nchstats = &nchstats[i];
1596 TAILQ_INIT(&ncneglist);
1597 nchashtbl = hashinit(desiredvnodes*2, M_VFSCACHE, &nchash);
1598 nclockwarn = 1 * hz;
1602 * Called from start_init() to bootstrap the root filesystem. Returns
1603 * a referenced, unlocked namecache record.
1606 cache_allocroot(struct mount *mp, struct vnode *vp)
1608 struct namecache *ncp = cache_alloc(0);
1610 ncp->nc_flag |= NCF_MOUNTPT | NCF_ROOT;
1612 cache_setvp(ncp, vp);
1617 * vfs_cache_setroot()
1619 * Create an association between the root of our namecache and
1620 * the root vnode. This routine may be called several times during
1623 * If the caller intends to save the returned namecache pointer somewhere
1624 * it must cache_hold() it.
1627 vfs_cache_setroot(struct vnode *nvp, struct namecache *ncp)
1630 struct namecache *oncp;
1644 * XXX OLD API COMPAT FUNCTION. This really messes up the new namecache
1645 * topology and is being removed as quickly as possible. The new VOP_N*()
1646 * API calls are required to make specific adjustments using the supplied
1647 * ncp pointers rather then just bogusly purging random vnodes.
1649 * Invalidate all namecache entries to a particular vnode as well as
1650 * any direct children of that vnode in the namecache. This is a
1651 * 'catch all' purge used by filesystems that do not know any better.
1653 * A new vnode v_id is generated. Note that no vnode will ever have a
1656 * Note that the linkage between the vnode and its namecache entries will
1657 * be removed, but the namecache entries themselves might stay put due to
1658 * active references from elsewhere in the system or due to the existance of
1659 * the children. The namecache topology is left intact even if we do not
1660 * know what the vnode association is. Such entries will be marked
1663 * XXX: Only time and the size of v_id prevents this from failing:
1664 * XXX: In theory we should hunt down all (struct vnode*, v_id)
1665 * XXX: soft references and nuke them, at least on the global
1666 * XXX: v_id wraparound. The period of resistance can be extended
1667 * XXX: by incrementing each vnodes v_id individually instead of
1668 * XXX: using the global v_id.
1671 cache_purge(struct vnode *vp)
1673 static u_long nextid;
1675 cache_inval_vp(vp, CINV_DESTROY | CINV_CHILDREN);
1678 * Calculate a new unique id for ".." handling
1682 } while (nextid == vp->v_id || nextid == 0);
1687 * Flush all entries referencing a particular filesystem.
1689 * Since we need to check it anyway, we will flush all the invalid
1690 * entries at the same time.
1693 cache_purgevfs(struct mount *mp)
1695 struct nchashhead *nchpp;
1696 struct namecache *ncp, *nnp;
1699 * Scan hash tables for applicable entries.
1701 for (nchpp = &nchashtbl[nchash]; nchpp >= nchashtbl; nchpp--) {
1702 ncp = LIST_FIRST(nchpp);
1706 nnp = LIST_NEXT(ncp, nc_hash);
1709 if (ncp->nc_mount == mp) {
1720 static int disablecwd;
1721 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, "");
1723 static u_long numcwdcalls; STATNODE(CTLFLAG_RD, numcwdcalls, &numcwdcalls);
1724 static u_long numcwdfail1; STATNODE(CTLFLAG_RD, numcwdfail1, &numcwdfail1);
1725 static u_long numcwdfail2; STATNODE(CTLFLAG_RD, numcwdfail2, &numcwdfail2);
1726 static u_long numcwdfail3; STATNODE(CTLFLAG_RD, numcwdfail3, &numcwdfail3);
1727 static u_long numcwdfail4; STATNODE(CTLFLAG_RD, numcwdfail4, &numcwdfail4);
1728 static u_long numcwdfound; STATNODE(CTLFLAG_RD, numcwdfound, &numcwdfound);
1731 __getcwd(struct __getcwd_args *uap)
1741 buflen = uap->buflen;
1744 if (buflen > MAXPATHLEN)
1745 buflen = MAXPATHLEN;
1747 buf = malloc(buflen, M_TEMP, M_WAITOK);
1748 bp = kern_getcwd(buf, buflen, &error);
1750 error = copyout(bp, uap->buf, strlen(bp) + 1);
1756 kern_getcwd(char *buf, size_t buflen, int *error)
1758 struct proc *p = curproc;
1760 int i, slash_prefixed;
1761 struct filedesc *fdp;
1762 struct namecache *ncp;
1771 ncp = fdp->fd_ncdir;
1772 while (ncp && ncp != fdp->fd_nrdir && (ncp->nc_flag & NCF_ROOT) == 0) {
1773 if (ncp->nc_flag & NCF_MOUNTPT) {
1774 if (ncp->nc_mount == NULL) {
1775 *error = EBADF; /* forced unmount? */
1778 ncp = ncp->nc_parent;
1781 for (i = ncp->nc_nlen - 1; i >= 0; i--) {
1787 *--bp = ncp->nc_name[i];
1796 ncp = ncp->nc_parent;
1803 if (!slash_prefixed) {
1817 * Thus begins the fullpath magic.
1821 #define STATNODE(name) \
1822 static u_int name; \
1823 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "")
1825 static int disablefullpath;
1826 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW,
1827 &disablefullpath, 0, "");
1829 STATNODE(numfullpathcalls);
1830 STATNODE(numfullpathfail1);
1831 STATNODE(numfullpathfail2);
1832 STATNODE(numfullpathfail3);
1833 STATNODE(numfullpathfail4);
1834 STATNODE(numfullpathfound);
1837 cache_fullpath(struct proc *p, struct namecache *ncp, char **retbuf, char **freebuf)
1840 int i, slash_prefixed;
1841 struct namecache *fd_nrdir;
1845 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1846 bp = buf + MAXPATHLEN - 1;
1849 fd_nrdir = p->p_fd->fd_nrdir;
1853 while (ncp && ncp != fd_nrdir && (ncp->nc_flag & NCF_ROOT) == 0) {
1854 if (ncp->nc_flag & NCF_MOUNTPT) {
1855 if (ncp->nc_mount == NULL) {
1859 ncp = ncp->nc_parent;
1862 for (i = ncp->nc_nlen - 1; i >= 0; i--) {
1868 *--bp = ncp->nc_name[i];
1877 ncp = ncp->nc_parent;
1884 if (p != NULL && (ncp->nc_flag & NCF_ROOT) && ncp != fd_nrdir) {
1885 bp = buf + MAXPATHLEN - 1;
1889 if (!slash_prefixed) {
1905 vn_fullpath(struct proc *p, struct vnode *vn, char **retbuf, char **freebuf)
1907 struct namecache *ncp;
1910 if (disablefullpath)
1916 /* vn is NULL, client wants us to use p->p_textvp */
1918 if ((vn = p->p_textvp) == NULL)
1921 TAILQ_FOREACH(ncp, &vn->v_namecache, nc_vnode) {
1929 return(cache_fullpath(p, ncp, retbuf, freebuf));