2 * Copyright (c) 1989, 1993, 1995
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * Poul-Henning Kamp of the FreeBSD Project.
8 * Redistribution and use in source and binary forms, with or without
9 * 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 the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/kernel.h>
42 #include <sys/mutex.h>
43 #include <sys/sysctl.h>
44 #include <sys/mount.h>
45 #include <sys/vnode.h>
46 #include <sys/namei.h>
47 #include <sys/malloc.h>
48 #include <sys/syscallsubr.h>
49 #include <sys/sysproto.h>
51 #include <sys/filedesc.h>
52 #include <sys/fnv_hash.h>
57 * This structure describes the elements in the cache of recent
58 * names looked up by namei.
62 LIST_ENTRY(namecache) nc_hash; /* hash chain */
63 LIST_ENTRY(namecache) nc_src; /* source vnode list */
64 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */
65 struct vnode *nc_dvp; /* vnode of parent of name */
66 struct vnode *nc_vp; /* vnode the name refers to */
67 u_char nc_flag; /* flag bits */
68 u_char nc_nlen; /* length of name */
69 char nc_name[0]; /* segment name */
73 * Name caching works as follows:
75 * Names found by directory scans are retained in a cache
76 * for future reference. It is managed LRU, so frequently
77 * used names will hang around. Cache is indexed by hash value
78 * obtained from (vp, name) where vp refers to the directory
81 * If it is a "negative" entry, (i.e. for a name that is known NOT to
82 * exist) the vnode pointer will be NULL.
84 * Upon reaching the last segment of a path, if the reference
85 * is for DELETE, or NOCACHE is set (rewrite), and the
86 * name is located in the cache, it will be dropped.
90 * Structures associated with name cacheing.
92 #define NCHHASH(hash) \
93 (&nchashtbl[(hash) & nchash])
94 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */
95 static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */
96 static u_long nchash; /* size of hash table */
97 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, "");
98 static u_long ncnegfactor = 16; /* ratio of negative entries */
99 SYSCTL_ULONG(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, "");
100 static u_long numneg; /* number of cache entries allocated */
101 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, "");
102 static u_long numcache; /* number of cache entries allocated */
103 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, "");
104 static u_long numcachehv; /* number of cache entries with vnodes held */
105 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, "");
107 static u_long numcachepl; /* number of cache purge for leaf entries */
108 SYSCTL_ULONG(_debug, OID_AUTO, numcachepl, CTLFLAG_RD, &numcachepl, 0, "");
110 struct nchstats nchstats; /* cache effectiveness statistics */
112 static struct mtx cache_lock;
113 MTX_SYSINIT(vfscache, &cache_lock, "Name Cache", MTX_DEF);
115 #define CACHE_LOCK() mtx_lock(&cache_lock)
116 #define CACHE_UNLOCK() mtx_unlock(&cache_lock)
119 * UMA zones for the VFS cache.
121 * The small cache is used for entries with short names, which are the
122 * most common. The large cache is used for entries which are too big to
123 * fit in the small cache.
125 static uma_zone_t cache_zone_small;
126 static uma_zone_t cache_zone_large;
128 #define CACHE_PATH_CUTOFF 32
129 #define CACHE_ZONE_SMALL (sizeof(struct namecache) + CACHE_PATH_CUTOFF)
130 #define CACHE_ZONE_LARGE (sizeof(struct namecache) + NAME_MAX)
132 #define cache_alloc(len) uma_zalloc(((len) <= CACHE_PATH_CUTOFF) ? \
133 cache_zone_small : cache_zone_large, M_WAITOK)
134 #define cache_free(ncp) do { \
136 uma_zfree(((ncp)->nc_nlen <= CACHE_PATH_CUTOFF) ? \
137 cache_zone_small : cache_zone_large, (ncp)); \
140 static int doingcache = 1; /* 1 => enable the cache */
141 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, "");
143 /* Export size information to userland */
144 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, 0,
145 sizeof(struct namecache), "");
148 * The new name cache statistics
150 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics");
151 #define STATNODE(mode, name, var) \
152 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, "");
153 STATNODE(CTLFLAG_RD, numneg, &numneg);
154 STATNODE(CTLFLAG_RD, numcache, &numcache);
155 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls);
156 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits);
157 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits);
158 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks);
159 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss);
160 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap);
161 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps);
162 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits);
163 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps);
164 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits);
166 SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD, &nchstats,
167 sizeof(nchstats), "LU", "VFS cache effectiveness statistics");
171 static void cache_zap(struct namecache *ncp);
172 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
173 char *buf, char **retbuf, u_int buflen);
175 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries");
178 * Flags in namecache.nc_flag
183 * Grab an atomic snapshot of the name cache hash chain lengths
185 SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats");
188 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS)
191 struct nchashhead *ncpp;
192 struct namecache *ncp;
196 n_nchash = nchash + 1; /* nchash is max index, not count */
198 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int));
200 /* Scan hash tables for applicable entries */
201 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
204 LIST_FOREACH(ncp, ncpp, nc_hash) {
208 error = SYSCTL_OUT(req, &count, sizeof(count));
214 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD,
215 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", "nchash chain lengths");
218 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS)
221 struct nchashhead *ncpp;
222 struct namecache *ncp;
224 int count, maxlength, used, pct;
227 return SYSCTL_OUT(req, 0, 4 * sizeof(int));
229 n_nchash = nchash + 1; /* nchash is max index, not count */
233 /* Scan hash tables for applicable entries */
234 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
237 LIST_FOREACH(ncp, ncpp, nc_hash) {
243 if (maxlength < count)
246 n_nchash = nchash + 1;
247 pct = (used * 100 * 100) / n_nchash;
248 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash));
251 error = SYSCTL_OUT(req, &used, sizeof(used));
254 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength));
257 error = SYSCTL_OUT(req, &pct, sizeof(pct));
262 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD,
263 0, 0, sysctl_debug_hashstat_nchash, "I", "nchash chain lengths");
268 * Removes a namecache entry from cache, whether it contains an actual
269 * pointer to a vnode or if it is just a negative cache entry.
273 struct namecache *ncp;
277 mtx_assert(&cache_lock, MA_OWNED);
278 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp);
280 LIST_REMOVE(ncp, nc_hash);
281 LIST_REMOVE(ncp, nc_src);
282 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) {
287 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst);
288 ncp->nc_vp->v_dd = NULL;
290 TAILQ_REMOVE(&ncneg, ncp, nc_dst);
300 * Lookup an entry in the cache
302 * Lookup is called with dvp pointing to the directory to search,
303 * cnp pointing to the name of the entry being sought. If the lookup
304 * succeeds, the vnode is returned in *vpp, and a status of -1 is
305 * returned. If the lookup determines that the name does not exist
306 * (negative cacheing), a status of ENOENT is returned. If the lookup
307 * fails, a status of zero is returned.
309 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is
310 * unlocked. If we're looking up . an extra ref is taken, but the lock is
311 * not recursively acquired.
315 cache_lookup(dvp, vpp, cnp)
318 struct componentname *cnp;
320 struct namecache *ncp;
325 cnp->cn_flags &= ~MAKEENTRY;
332 if (cnp->cn_nameptr[0] == '.') {
333 if (cnp->cn_namelen == 1) {
335 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .",
336 dvp, cnp->cn_nameptr);
340 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
342 if (dvp->v_dd == NULL ||
343 (cnp->cn_flags & MAKEENTRY) == 0) {
348 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..",
349 dvp, cnp->cn_nameptr, *vpp);
354 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT);
355 hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
356 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
358 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
359 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))
363 /* We failed to find an entry */
365 if ((cnp->cn_flags & MAKEENTRY) == 0) {
375 /* We don't want to have an entry, so dump it */
376 if ((cnp->cn_flags & MAKEENTRY) == 0) {
378 nchstats.ncs_badhits++;
384 /* We found a "positive" match, return the vnode */
387 nchstats.ncs_goodhits++;
389 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p",
390 dvp, cnp->cn_nameptr, *vpp, ncp);
394 /* We found a negative match, and want to create it, so purge */
395 if (cnp->cn_nameiop == CREATE) {
397 nchstats.ncs_badhits++;
405 * We found a "negative" match, so we shift it to the end of
406 * the "negative" cache entries queue to satisfy LRU. Also,
407 * check to see if the entry is a whiteout; indicate this to
408 * the componentname, if so.
410 TAILQ_REMOVE(&ncneg, ncp, nc_dst);
411 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
412 nchstats.ncs_neghits++;
413 if (ncp->nc_flag & NCF_WHITE)
414 cnp->cn_flags |= ISWHITEOUT;
420 * On success we return a locked and ref'd vnode as per the lookup
423 if (dvp == *vpp) { /* lookup on "." */
427 * When we lookup "." we still can be asked to lock it
430 ltype = cnp->cn_lkflags & LK_TYPE_MASK;
431 if (ltype == VOP_ISLOCKED(*vpp))
433 else if (ltype == LK_EXCLUSIVE)
434 vn_lock(*vpp, LK_UPGRADE | LK_RETRY);
437 ltype = 0; /* silence gcc warning */
438 if (cnp->cn_flags & ISDOTDOT) {
439 ltype = VOP_ISLOCKED(dvp);
444 error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread);
445 if (cnp->cn_flags & ISDOTDOT)
446 vn_lock(dvp, ltype | LK_RETRY);
451 if ((cnp->cn_flags & ISLASTCN) &&
452 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) {
453 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup");
459 * Add an entry to the cache.
462 cache_enter(dvp, vp, cnp)
465 struct componentname *cnp;
467 struct namecache *ncp;
468 struct nchashhead *ncpp;
474 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr);
475 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp,
476 ("cahe_enter: Adding a doomed vnode"));
481 if (cnp->cn_nameptr[0] == '.') {
482 if (cnp->cn_namelen == 1) {
486 * For dotdot lookups only cache the v_dd pointer if the
487 * directory has a link back to its parent via v_cache_dst.
488 * Without this an unlinked directory would keep a soft
489 * reference to its parent which could not be NULLd at
490 * cache_purge() time.
492 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
494 if (!TAILQ_EMPTY(&dvp->v_cache_dst))
505 * Calculate the hash key and setup as much of the new
506 * namecache entry as possible before acquiring the lock.
508 ncp = cache_alloc(cnp->cn_namelen);
511 len = ncp->nc_nlen = cnp->cn_namelen;
512 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT);
513 bcopy(cnp->cn_nameptr, ncp->nc_name, len);
514 hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
518 * See if this vnode is already in the cache with this name.
519 * This can happen with concurrent lookups of the same path
523 struct namecache *n2;
525 TAILQ_FOREACH(n2, &vp->v_cache_dst, nc_dst) {
526 if (n2->nc_dvp == dvp &&
527 n2->nc_nlen == cnp->cn_namelen &&
528 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) {
539 ncp->nc_flag = cnp->cn_flags & ISWHITEOUT ? NCF_WHITE : 0;
540 } else if (vp->v_type == VDIR) {
547 * Insert the new namecache entry into the appropriate chain
548 * within the cache entries table.
550 ncpp = NCHHASH(hash);
551 LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
552 if (LIST_EMPTY(&dvp->v_cache_src)) {
556 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src);
558 * If the entry is "negative", we place it into the
559 * "negative" cache queue, otherwise, we place it into the
560 * destination vnode's cache entries queue.
563 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst);
565 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
567 if (numneg * ncnegfactor > numcache) {
568 ncp = TAILQ_FIRST(&ncneg);
579 * Name cache initialization, from vfs_init() when we are booting
582 nchinit(void *dummy __unused)
587 cache_zone_small = uma_zcreate("S VFS Cache", CACHE_ZONE_SMALL, NULL,
588 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
589 cache_zone_large = uma_zcreate("L VFS Cache", CACHE_ZONE_LARGE, NULL,
590 NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
592 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash);
594 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
598 * Invalidate all entries to a particular vnode.
605 CTR1(KTR_VFS, "cache_purge(%p)", vp);
607 while (!LIST_EMPTY(&vp->v_cache_src))
608 cache_zap(LIST_FIRST(&vp->v_cache_src));
609 while (!TAILQ_EMPTY(&vp->v_cache_dst))
610 cache_zap(TAILQ_FIRST(&vp->v_cache_dst));
616 * Flush all entries referencing a particular filesystem.
622 struct nchashhead *ncpp;
623 struct namecache *ncp, *nnp;
625 /* Scan hash tables for applicable entries */
627 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) {
628 LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) {
629 if (ncp->nc_dvp->v_mount == mp)
637 * Perform canonical checks and cache lookup and pass on to filesystem
638 * through the vop_cachedlookup only if needed.
643 struct vop_lookup_args /* {
645 struct vnode **a_vpp;
646 struct componentname *a_cnp;
651 struct vnode **vpp = ap->a_vpp;
652 struct componentname *cnp = ap->a_cnp;
653 struct ucred *cred = cnp->cn_cred;
654 int flags = cnp->cn_flags;
655 struct thread *td = cnp->cn_thread;
660 if (dvp->v_type != VDIR)
663 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
664 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
667 error = VOP_ACCESS(dvp, VEXEC, cred, td);
671 error = cache_lookup(dvp, vpp, cnp);
673 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
680 #ifndef _SYS_SYSPROTO_H_
681 struct __getcwd_args {
688 * XXX All of these sysctls would probably be more productive dead.
690 static int disablecwd;
691 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0,
692 "Disable the getcwd syscall");
694 /* Implementation of the getcwd syscall. */
698 struct __getcwd_args *uap;
701 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen));
705 kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen)
708 struct filedesc *fdp;
715 if (buflen > MAXPATHLEN)
718 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK);
719 fdp = td->td_proc->p_fd;
721 error = vn_fullpath1(td, fdp->fd_cdir, fdp->fd_rdir, tmpbuf,
723 FILEDESC_SUNLOCK(fdp);
726 if (bufseg == UIO_SYSSPACE)
727 bcopy(bp, buf, strlen(bp) + 1);
729 error = copyout(bp, buf, strlen(bp) + 1);
731 free(tmpbuf, M_TEMP);
736 * Thus begins the fullpath magic.
740 #define STATNODE(name) \
742 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, "")
744 static int disablefullpath;
745 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0,
746 "Disable the vn_fullpath function");
748 /* These count for kern___getcwd(), too. */
749 STATNODE(numfullpathcalls);
750 STATNODE(numfullpathfail1);
751 STATNODE(numfullpathfail2);
752 STATNODE(numfullpathfail4);
753 STATNODE(numfullpathfound);
756 * Retrieve the full filesystem path that correspond to a vnode from the name
757 * cache (if available)
760 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf)
763 struct filedesc *fdp;
771 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
772 fdp = td->td_proc->p_fd;
774 error = vn_fullpath1(td, vn, fdp->fd_rdir, buf, retbuf, MAXPATHLEN);
775 FILEDESC_SUNLOCK(fdp);
785 * This function is similar to vn_fullpath, but it attempts to lookup the
786 * pathname relative to the global root mount point. This is required for the
787 * auditing sub-system, as audited pathnames must be absolute, relative to the
788 * global root mount point.
791 vn_fullpath_global(struct thread *td, struct vnode *vn,
792 char **retbuf, char **freebuf)
801 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
802 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN);
811 * The magic behind kern___getcwd() and vn_fullpath().
814 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
815 char *buf, char **retbuf, u_int buflen)
818 int error, i, slash_prefixed;
819 struct namecache *ncp;
821 bp = buf + buflen - 1;
828 if (vp->v_type != VDIR) {
829 ncp = TAILQ_FIRST(&vp->v_cache_dst);
835 for (i = ncp->nc_nlen - 1; i >= 0 && bp > buf; i--)
836 *--bp = ncp->nc_name[i];
846 while (vp != rdir && vp != rootvnode) {
847 if (vp->v_vflag & VV_ROOT) {
848 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */
852 vp = vp->v_mount->mnt_vnodecovered;
855 if (vp->v_dd == NULL) {
860 ncp = TAILQ_FIRST(&vp->v_cache_dst);
866 MPASS(ncp->nc_dvp == vp->v_dd);
867 for (i = ncp->nc_nlen - 1; i >= 0 && bp != buf; i--)
868 *--bp = ncp->nc_name[i];
882 if (!slash_prefixed) {
899 vn_commname(struct vnode *vp, char *buf, u_int buflen)
901 struct namecache *ncp;
905 ncp = TAILQ_FIRST(&vp->v_cache_dst);
910 l = min(ncp->nc_nlen, buflen - 1);
911 memcpy(buf, ncp->nc_name, l);