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 * 3. 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 "opt_ktrace.h"
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/counter.h>
43 #include <sys/filedesc.h>
44 #include <sys/fnv_hash.h>
45 #include <sys/kernel.h>
47 #include <sys/malloc.h>
48 #include <sys/fcntl.h>
49 #include <sys/mount.h>
50 #include <sys/namei.h>
52 #include <sys/rwlock.h>
55 #include <sys/syscallsubr.h>
56 #include <sys/sysctl.h>
57 #include <sys/sysproto.h>
58 #include <sys/vnode.h>
60 #include <sys/ktrace.h>
65 SDT_PROVIDER_DECLARE(vfs);
66 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *",
68 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *",
70 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *");
71 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *",
72 "char *", "struct vnode *");
73 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *");
74 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int",
75 "struct vnode *", "char *");
76 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *",
78 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative,
79 "struct vnode *", "char *");
80 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *",
82 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *");
83 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *");
84 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *");
85 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *",
87 SDT_PROBE_DEFINE3(vfs, namecache, zap_negative, done, "struct vnode *",
89 SDT_PROBE_DEFINE3(vfs, namecache, shrink_negative, done, "struct vnode *",
93 * This structure describes the elements in the cache of recent
94 * names looked up by namei.
98 LIST_ENTRY(namecache) nc_hash; /* hash chain */
99 LIST_ENTRY(namecache) nc_src; /* source vnode list */
100 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */
101 struct vnode *nc_dvp; /* vnode of parent of name */
103 struct vnode *nu_vp; /* vnode the name refers to */
104 u_int nu_neghits; /* negative entry hits */
106 u_char nc_flag; /* flag bits */
107 u_char nc_nlen; /* length of name */
108 char nc_name[0]; /* segment name + nul */
112 * struct namecache_ts repeats struct namecache layout up to the
114 * struct namecache_ts is used in place of struct namecache when time(s) need
115 * to be stored. The nc_dotdottime field is used when a cache entry is mapping
116 * both a non-dotdot directory name plus dotdot for the directory's
119 struct namecache_ts {
120 LIST_ENTRY(namecache) nc_hash; /* hash chain */
121 LIST_ENTRY(namecache) nc_src; /* source vnode list */
122 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */
123 struct vnode *nc_dvp; /* vnode of parent of name */
125 struct vnode *nu_vp; /* vnode the name refers to */
126 u_int nu_neghits; /* negative entry hits */
128 u_char nc_flag; /* flag bits */
129 u_char nc_nlen; /* length of name */
130 struct timespec nc_time; /* timespec provided by fs */
131 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */
132 int nc_ticks; /* ticks value when entry was added */
133 char nc_name[0]; /* segment name + nul */
136 #define nc_vp n_un.nu_vp
137 #define nc_neghits n_un.nu_neghits
140 * Flags in namecache.nc_flag
142 #define NCF_WHITE 0x01
143 #define NCF_ISDOTDOT 0x02
146 #define NCF_DVDROP 0x10
147 #define NCF_NEGATIVE 0x20
148 #define NCF_HOTNEGATIVE 0x40
151 * Name caching works as follows:
153 * Names found by directory scans are retained in a cache
154 * for future reference. It is managed LRU, so frequently
155 * used names will hang around. Cache is indexed by hash value
156 * obtained from (vp, name) where vp refers to the directory
159 * If it is a "negative" entry, (i.e. for a name that is known NOT to
160 * exist) the vnode pointer will be NULL.
162 * Upon reaching the last segment of a path, if the reference
163 * is for DELETE, or NOCACHE is set (rewrite), and the
164 * name is located in the cache, it will be dropped.
166 * These locks are used (in the order in which they can be taken):
168 * vnodelock mtx vnode lists and v_cache_dd field protection
169 * bucketlock rwlock for access to given set of hash buckets
170 * neglist mtx negative entry LRU management
172 * Additionally, ncneg_shrink_lock mtx is used to have at most one thread
173 * shrinking the LRU list.
175 * It is legal to take multiple vnodelock and bucketlock locks. The locking
176 * order is lower address first. Both are recursive.
178 * "." lookups are lockless.
180 * ".." and vnode -> name lookups require vnodelock.
182 * name -> vnode lookup requires the relevant bucketlock to be held for reading.
184 * Insertions and removals of entries require involved vnodes and bucketlocks
185 * to be write-locked to prevent other threads from seeing the entry.
187 * Some lookups result in removal of the found entry (e.g. getting rid of a
188 * negative entry with the intent to create a positive one), which poses a
189 * problem when multiple threads reach the state. Similarly, two different
190 * threads can purge two different vnodes and try to remove the same name.
192 * If the already held vnode lock is lower than the second required lock, we
193 * can just take the other lock. However, in the opposite case, this could
194 * deadlock. As such, this is resolved by trylocking and if that fails unlocking
195 * the first node, locking everything in order and revalidating the state.
199 * Structures associated with name caching.
201 #define NCHHASH(hash) \
202 (&nchashtbl[(hash) & nchash])
203 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */
204 static u_long nchash; /* size of hash table */
205 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0,
206 "Size of namecache hash table");
207 static u_long ncnegfactor = 16; /* ratio of negative entries */
208 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0,
209 "Ratio of negative namecache entries");
210 static u_long numneg; /* number of negative entries allocated */
211 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0,
212 "Number of negative entries in namecache");
213 static u_long numcache; /* number of cache entries allocated */
214 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0,
215 "Number of namecache entries");
216 static u_long numcachehv; /* number of cache entries with vnodes held */
217 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0,
218 "Number of namecache entries with vnodes held");
219 u_int ncsizefactor = 2;
220 SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0,
221 "Size factor for namecache");
222 static u_int ncpurgeminvnodes;
223 SYSCTL_UINT(_vfs, OID_AUTO, ncpurgeminvnodes, CTLFLAG_RW, &ncpurgeminvnodes, 0,
224 "Number of vnodes below which purgevfs ignores the request");
225 static u_int ncneghitsrequeue = 8;
226 SYSCTL_UINT(_vfs, OID_AUTO, ncneghitsrequeue, CTLFLAG_RW, &ncneghitsrequeue, 0,
227 "Number of hits to requeue a negative entry in the LRU list");
229 struct nchstats nchstats; /* cache effectiveness statistics */
231 static struct mtx ncneg_shrink_lock;
232 MTX_SYSINIT(vfscache_shrink_neg, &ncneg_shrink_lock, "Name Cache shrink neg",
237 TAILQ_HEAD(, namecache) nl_list;
238 } __aligned(CACHE_LINE_SIZE);
240 static struct neglist *neglists;
241 static struct neglist ncneg_hot;
243 static int shrink_list_turn;
245 static u_int numneglists;
246 static inline struct neglist *
247 NCP2NEGLIST(struct namecache *ncp)
250 return (&neglists[(((uintptr_t)(ncp) >> 8) % numneglists)]);
253 static u_int numbucketlocks;
254 static struct rwlock_padalign *bucketlocks;
255 #define HASH2BUCKETLOCK(hash) \
256 ((struct rwlock *)(&bucketlocks[((hash) % numbucketlocks)]))
258 static u_int numvnodelocks;
259 static struct mtx *vnodelocks;
260 static inline struct mtx *
261 VP2VNODELOCK(struct vnode *vp)
267 vlp = &vnodelocks[(((uintptr_t)(vp) >> 8) % numvnodelocks)];
272 * UMA zones for the VFS cache.
274 * The small cache is used for entries with short names, which are the
275 * most common. The large cache is used for entries which are too big to
276 * fit in the small cache.
278 static uma_zone_t cache_zone_small;
279 static uma_zone_t cache_zone_small_ts;
280 static uma_zone_t cache_zone_large;
281 static uma_zone_t cache_zone_large_ts;
283 #define CACHE_PATH_CUTOFF 35
285 static struct namecache *
286 cache_alloc(int len, int ts)
289 if (len > CACHE_PATH_CUTOFF) {
291 return (uma_zalloc(cache_zone_large_ts, M_WAITOK));
293 return (uma_zalloc(cache_zone_large, M_WAITOK));
296 return (uma_zalloc(cache_zone_small_ts, M_WAITOK));
298 return (uma_zalloc(cache_zone_small, M_WAITOK));
302 cache_free(struct namecache *ncp)
308 ts = ncp->nc_flag & NCF_TS;
309 if ((ncp->nc_flag & NCF_DVDROP) != 0)
311 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) {
313 uma_zfree(cache_zone_small_ts, ncp);
315 uma_zfree(cache_zone_small, ncp);
317 uma_zfree(cache_zone_large_ts, ncp);
319 uma_zfree(cache_zone_large, ncp);
323 nc_get_name(struct namecache *ncp)
325 struct namecache_ts *ncp_ts;
327 if ((ncp->nc_flag & NCF_TS) == 0)
328 return (ncp->nc_name);
329 ncp_ts = (struct namecache_ts *)ncp;
330 return (ncp_ts->nc_name);
334 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp)
337 KASSERT((ncp->nc_flag & NCF_TS) != 0 ||
338 (tsp == NULL && ticksp == NULL),
342 *tsp = ((struct namecache_ts *)ncp)->nc_time;
344 *ticksp = ((struct namecache_ts *)ncp)->nc_ticks;
347 static int doingcache = 1; /* 1 => enable the cache */
348 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0,
349 "VFS namecache enabled");
351 /* Export size information to userland */
352 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR,
353 sizeof(struct namecache), "sizeof(struct namecache)");
356 * The new name cache statistics
358 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0,
359 "Name cache statistics");
360 #define STATNODE_ULONG(name, descr) \
361 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr);
362 #define STATNODE_COUNTER(name, descr) \
363 static counter_u64_t name; \
364 SYSCTL_COUNTER_U64(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, descr);
365 STATNODE_ULONG(numneg, "Number of negative cache entries");
366 STATNODE_ULONG(numcache, "Number of cache entries");
367 STATNODE_COUNTER(numcalls, "Number of cache lookups");
368 STATNODE_COUNTER(dothits, "Number of '.' hits");
369 STATNODE_COUNTER(dotdothits, "Number of '..' hits");
370 STATNODE_COUNTER(numchecks, "Number of checks in lookup");
371 STATNODE_COUNTER(nummiss, "Number of cache misses");
372 STATNODE_COUNTER(nummisszap, "Number of cache misses we do not want to cache");
373 STATNODE_COUNTER(numposzaps,
374 "Number of cache hits (positive) we do not want to cache");
375 STATNODE_COUNTER(numposhits, "Number of cache hits (positive)");
376 STATNODE_COUNTER(numnegzaps,
377 "Number of cache hits (negative) we do not want to cache");
378 STATNODE_COUNTER(numneghits, "Number of cache hits (negative)");
379 /* These count for kern___getcwd(), too. */
380 STATNODE_COUNTER(numfullpathcalls, "Number of fullpath search calls");
381 STATNODE_COUNTER(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)");
382 STATNODE_COUNTER(numfullpathfail2,
383 "Number of fullpath search errors (VOP_VPTOCNP failures)");
384 STATNODE_COUNTER(numfullpathfail4, "Number of fullpath search errors (ENOMEM)");
385 STATNODE_COUNTER(numfullpathfound, "Number of successful fullpath calls");
386 static long zap_and_exit_bucket_fail; STATNODE_ULONG(zap_and_exit_bucket_fail,
387 "Number of times zap_and_exit failed to lock");
388 static long cache_lock_vnodes_cel_3_failures;
389 STATNODE_ULONG(cache_lock_vnodes_cel_3_failures,
390 "Number of times 3-way vnode locking failed");
392 static void cache_zap_locked(struct namecache *ncp, bool neg_locked);
393 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
394 char *buf, char **retbuf, u_int buflen);
396 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries");
398 static int cache_yield;
399 SYSCTL_INT(_vfs_cache, OID_AUTO, yield, CTLFLAG_RD, &cache_yield, 0,
400 "Number of times cache called yield");
403 cache_maybe_yield(void)
406 if (should_yield()) {
408 kern_yield(PRI_USER);
413 cache_assert_vlp_locked(struct mtx *vlp)
417 mtx_assert(vlp, MA_OWNED);
421 cache_assert_vnode_locked(struct vnode *vp)
425 vlp = VP2VNODELOCK(vp);
426 cache_assert_vlp_locked(vlp);
430 cache_get_hash(char *name, u_char len, struct vnode *dvp)
434 hash = fnv_32_buf(name, len, FNV1_32_INIT);
435 hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
439 static inline struct rwlock *
440 NCP2BUCKETLOCK(struct namecache *ncp)
444 hash = cache_get_hash(nc_get_name(ncp), ncp->nc_nlen, ncp->nc_dvp);
445 return (HASH2BUCKETLOCK(hash));
450 cache_assert_bucket_locked(struct namecache *ncp, int mode)
454 blp = NCP2BUCKETLOCK(ncp);
455 rw_assert(blp, mode);
458 #define cache_assert_bucket_locked(x, y) do { } while (0)
461 #define cache_sort(x, y) _cache_sort((void **)(x), (void **)(y))
463 _cache_sort(void **p1, void **p2)
475 cache_lock_all_buckets(void)
479 for (i = 0; i < numbucketlocks; i++)
480 rw_wlock(&bucketlocks[i]);
484 cache_unlock_all_buckets(void)
488 for (i = 0; i < numbucketlocks; i++)
489 rw_wunlock(&bucketlocks[i]);
493 cache_lock_all_vnodes(void)
497 for (i = 0; i < numvnodelocks; i++)
498 mtx_lock(&vnodelocks[i]);
502 cache_unlock_all_vnodes(void)
506 for (i = 0; i < numvnodelocks; i++)
507 mtx_unlock(&vnodelocks[i]);
511 cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2)
514 cache_sort(&vlp1, &vlp2);
518 if (!mtx_trylock(vlp1))
521 if (!mtx_trylock(vlp2)) {
531 cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2)
534 MPASS(vlp1 != NULL || vlp2 != NULL);
543 sysctl_nchstats(SYSCTL_HANDLER_ARGS)
545 struct nchstats snap;
547 if (req->oldptr == NULL)
548 return (SYSCTL_OUT(req, 0, sizeof(snap)));
551 snap.ncs_goodhits = counter_u64_fetch(numposhits);
552 snap.ncs_neghits = counter_u64_fetch(numneghits);
553 snap.ncs_badhits = counter_u64_fetch(numposzaps) +
554 counter_u64_fetch(numnegzaps);
555 snap.ncs_miss = counter_u64_fetch(nummisszap) +
556 counter_u64_fetch(nummiss);
558 return (SYSCTL_OUT(req, &snap, sizeof(snap)));
560 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD |
561 CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU",
562 "VFS cache effectiveness statistics");
566 * Grab an atomic snapshot of the name cache hash chain lengths
568 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL,
572 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS)
574 struct nchashhead *ncpp;
575 struct namecache *ncp;
576 int i, error, n_nchash, *cntbuf;
579 n_nchash = nchash + 1; /* nchash is max index, not count */
580 if (req->oldptr == NULL)
581 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int));
582 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK);
583 cache_lock_all_buckets();
584 if (n_nchash != nchash + 1) {
585 cache_unlock_all_buckets();
586 free(cntbuf, M_TEMP);
589 /* Scan hash tables counting entries */
590 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++)
591 LIST_FOREACH(ncp, ncpp, nc_hash)
593 cache_unlock_all_buckets();
594 for (error = 0, i = 0; i < n_nchash; i++)
595 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0)
597 free(cntbuf, M_TEMP);
600 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD|
601 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int",
602 "nchash chain lengths");
605 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS)
608 struct nchashhead *ncpp;
609 struct namecache *ncp;
611 int count, maxlength, used, pct;
614 return SYSCTL_OUT(req, 0, 4 * sizeof(int));
616 cache_lock_all_buckets();
617 n_nchash = nchash + 1; /* nchash is max index, not count */
621 /* Scan hash tables for applicable entries */
622 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
624 LIST_FOREACH(ncp, ncpp, nc_hash) {
629 if (maxlength < count)
632 n_nchash = nchash + 1;
633 cache_unlock_all_buckets();
634 pct = (used * 100) / (n_nchash / 100);
635 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash));
638 error = SYSCTL_OUT(req, &used, sizeof(used));
641 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength));
644 error = SYSCTL_OUT(req, &pct, sizeof(pct));
649 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD|
650 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I",
651 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)");
655 * Negative entries management
657 * A variation of LRU scheme is used. New entries are hashed into one of
658 * numneglists cold lists. Entries get promoted to the hot list on first hit.
659 * Partial LRU for the hot list is maintained by requeueing them every
660 * ncneghitsrequeue hits.
662 * The shrinker will demote hot list head and evict from the cold list in a
663 * round-robin manner.
666 cache_negative_hit(struct namecache *ncp)
668 struct neglist *neglist;
671 MPASS(ncp->nc_flag & NCF_NEGATIVE);
672 hits = atomic_fetchadd_int(&ncp->nc_neghits, 1);
673 if (ncp->nc_flag & NCF_HOTNEGATIVE) {
674 if ((hits % ncneghitsrequeue) != 0)
676 mtx_lock(&ncneg_hot.nl_lock);
677 if (ncp->nc_flag & NCF_HOTNEGATIVE) {
678 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst);
679 TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst);
680 mtx_unlock(&ncneg_hot.nl_lock);
684 * The shrinker cleared the flag and removed the entry from
685 * the hot list. Put it back.
688 mtx_lock(&ncneg_hot.nl_lock);
690 neglist = NCP2NEGLIST(ncp);
691 mtx_lock(&neglist->nl_lock);
692 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) {
693 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst);
694 TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst);
695 ncp->nc_flag |= NCF_HOTNEGATIVE;
697 mtx_unlock(&neglist->nl_lock);
698 mtx_unlock(&ncneg_hot.nl_lock);
702 cache_negative_insert(struct namecache *ncp, bool neg_locked)
704 struct neglist *neglist;
706 MPASS(ncp->nc_flag & NCF_NEGATIVE);
707 cache_assert_bucket_locked(ncp, RA_WLOCKED);
708 neglist = NCP2NEGLIST(ncp);
710 mtx_lock(&neglist->nl_lock);
712 mtx_assert(&neglist->nl_lock, MA_OWNED);
714 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst);
716 mtx_unlock(&neglist->nl_lock);
717 atomic_add_rel_long(&numneg, 1);
721 cache_negative_remove(struct namecache *ncp, bool neg_locked)
723 struct neglist *neglist;
724 bool hot_locked = false;
725 bool list_locked = false;
727 MPASS(ncp->nc_flag & NCF_NEGATIVE);
728 cache_assert_bucket_locked(ncp, RA_WLOCKED);
729 neglist = NCP2NEGLIST(ncp);
731 if (ncp->nc_flag & NCF_HOTNEGATIVE) {
733 mtx_lock(&ncneg_hot.nl_lock);
734 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) {
736 mtx_lock(&neglist->nl_lock);
740 mtx_lock(&neglist->nl_lock);
743 mtx_assert(&neglist->nl_lock, MA_OWNED);
744 mtx_assert(&ncneg_hot.nl_lock, MA_OWNED);
746 if (ncp->nc_flag & NCF_HOTNEGATIVE) {
747 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst);
749 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst);
752 mtx_unlock(&neglist->nl_lock);
754 mtx_unlock(&ncneg_hot.nl_lock);
755 atomic_subtract_rel_long(&numneg, 1);
759 cache_negative_shrink_select(int start, struct namecache **ncpp,
760 struct neglist **neglistpp)
762 struct neglist *neglist;
763 struct namecache *ncp;
768 for (i = start; i < numneglists; i++) {
769 neglist = &neglists[i];
770 if (TAILQ_FIRST(&neglist->nl_list) == NULL)
772 mtx_lock(&neglist->nl_lock);
773 ncp = TAILQ_FIRST(&neglist->nl_list);
776 mtx_unlock(&neglist->nl_lock);
779 *neglistpp = neglist;
784 cache_negative_zap_one(void)
786 struct namecache *ncp, *ncp2;
787 struct neglist *neglist;
791 if (!mtx_trylock(&ncneg_shrink_lock))
794 mtx_lock(&ncneg_hot.nl_lock);
795 ncp = TAILQ_FIRST(&ncneg_hot.nl_list);
797 neglist = NCP2NEGLIST(ncp);
798 mtx_lock(&neglist->nl_lock);
799 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst);
800 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst);
801 ncp->nc_flag &= ~NCF_HOTNEGATIVE;
802 mtx_unlock(&neglist->nl_lock);
805 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist);
807 if (shrink_list_turn == numneglists)
808 shrink_list_turn = 0;
809 if (ncp == NULL && shrink_list_turn == 0)
810 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist);
812 mtx_unlock(&ncneg_hot.nl_lock);
816 MPASS(ncp->nc_flag & NCF_NEGATIVE);
817 dvlp = VP2VNODELOCK(ncp->nc_dvp);
818 blp = NCP2BUCKETLOCK(ncp);
819 mtx_unlock(&neglist->nl_lock);
820 mtx_unlock(&ncneg_hot.nl_lock);
823 mtx_lock(&ncneg_hot.nl_lock);
824 mtx_lock(&neglist->nl_lock);
825 ncp2 = TAILQ_FIRST(&neglist->nl_list);
826 if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) ||
827 blp != NCP2BUCKETLOCK(ncp2) || !(ncp2->nc_flag & NCF_NEGATIVE)) {
831 SDT_PROBE3(vfs, namecache, shrink_negative, done, ncp->nc_dvp,
832 nc_get_name(ncp), ncp->nc_neghits);
834 cache_zap_locked(ncp, true);
836 mtx_unlock(&neglist->nl_lock);
837 mtx_unlock(&ncneg_hot.nl_lock);
841 mtx_unlock(&ncneg_shrink_lock);
846 * cache_zap_locked():
848 * Removes a namecache entry from cache, whether it contains an actual
849 * pointer to a vnode or if it is just a negative cache entry.
852 cache_zap_locked(struct namecache *ncp, bool neg_locked)
855 if (!(ncp->nc_flag & NCF_NEGATIVE))
856 cache_assert_vnode_locked(ncp->nc_vp);
857 cache_assert_vnode_locked(ncp->nc_dvp);
858 cache_assert_bucket_locked(ncp, RA_WLOCKED);
860 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp,
861 (ncp->nc_flag & NCF_NEGATIVE) ? NULL : ncp->nc_vp);
862 if (!(ncp->nc_flag & NCF_NEGATIVE)) {
863 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp,
864 nc_get_name(ncp), ncp->nc_vp);
866 SDT_PROBE3(vfs, namecache, zap_negative, done, ncp->nc_dvp,
867 nc_get_name(ncp), ncp->nc_neghits);
869 LIST_REMOVE(ncp, nc_hash);
870 if (!(ncp->nc_flag & NCF_NEGATIVE)) {
871 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst);
872 if (ncp == ncp->nc_vp->v_cache_dd)
873 ncp->nc_vp->v_cache_dd = NULL;
875 cache_negative_remove(ncp, neg_locked);
877 if (ncp->nc_flag & NCF_ISDOTDOT) {
878 if (ncp == ncp->nc_dvp->v_cache_dd)
879 ncp->nc_dvp->v_cache_dd = NULL;
881 LIST_REMOVE(ncp, nc_src);
882 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) {
883 ncp->nc_flag |= NCF_DVDROP;
884 atomic_subtract_rel_long(&numcachehv, 1);
887 atomic_subtract_rel_long(&numcache, 1);
891 cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp)
895 MPASS(ncp->nc_dvp == vp);
896 MPASS(ncp->nc_flag & NCF_NEGATIVE);
897 cache_assert_vnode_locked(vp);
899 blp = NCP2BUCKETLOCK(ncp);
901 cache_zap_locked(ncp, false);
906 cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp,
909 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock;
912 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp);
913 cache_assert_vnode_locked(vp);
915 if (ncp->nc_flag & NCF_NEGATIVE) {
920 cache_zap_negative_locked_vnode_kl(ncp, vp);
924 pvlp = VP2VNODELOCK(vp);
925 blp = NCP2BUCKETLOCK(ncp);
926 vlp1 = VP2VNODELOCK(ncp->nc_dvp);
927 vlp2 = VP2VNODELOCK(ncp->nc_vp);
929 if (*vlpp == vlp1 || *vlpp == vlp2) {
937 cache_sort(&vlp1, &vlp2);
942 if (!mtx_trylock(vlp1))
948 cache_zap_locked(ncp, false);
950 if (to_unlock != NULL)
951 mtx_unlock(to_unlock);
958 MPASS(*vlpp == NULL);
964 cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp)
966 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock;
970 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp);
971 cache_assert_vnode_locked(vp);
973 pvlp = VP2VNODELOCK(vp);
974 if (ncp->nc_flag & NCF_NEGATIVE) {
975 cache_zap_negative_locked_vnode_kl(ncp, vp);
979 blp = NCP2BUCKETLOCK(ncp);
980 vlp1 = VP2VNODELOCK(ncp->nc_dvp);
981 vlp2 = VP2VNODELOCK(ncp->nc_vp);
982 cache_sort(&vlp1, &vlp2);
987 if (!mtx_trylock(vlp1)) {
994 cache_zap_locked(ncp, false);
996 mtx_unlock(to_unlock);
1003 cache_zap_rlocked_bucket(struct namecache *ncp, struct rwlock *blp)
1005 struct mtx *dvlp, *vlp;
1007 cache_assert_bucket_locked(ncp, RA_RLOCKED);
1009 dvlp = VP2VNODELOCK(ncp->nc_dvp);
1011 if (!(ncp->nc_flag & NCF_NEGATIVE))
1012 vlp = VP2VNODELOCK(ncp->nc_vp);
1013 if (cache_trylock_vnodes(dvlp, vlp) == 0) {
1016 cache_zap_locked(ncp, false);
1018 cache_unlock_vnodes(dvlp, vlp);
1027 cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp,
1028 struct mtx **vlpp1, struct mtx **vlpp2)
1030 struct mtx *dvlp, *vlp;
1032 cache_assert_bucket_locked(ncp, RA_WLOCKED);
1034 dvlp = VP2VNODELOCK(ncp->nc_dvp);
1036 if (!(ncp->nc_flag & NCF_NEGATIVE))
1037 vlp = VP2VNODELOCK(ncp->nc_vp);
1038 cache_sort(&dvlp, &vlp);
1040 if (*vlpp1 == dvlp && *vlpp2 == vlp) {
1041 cache_zap_locked(ncp, false);
1042 cache_unlock_vnodes(dvlp, vlp);
1055 if (cache_trylock_vnodes(dvlp, vlp) == 0) {
1056 cache_zap_locked(ncp, false);
1057 cache_unlock_vnodes(dvlp, vlp);
1072 cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp)
1077 mtx_assert(vlp, MA_NOTOWNED);
1084 * Lookup an entry in the cache
1086 * Lookup is called with dvp pointing to the directory to search,
1087 * cnp pointing to the name of the entry being sought. If the lookup
1088 * succeeds, the vnode is returned in *vpp, and a status of -1 is
1089 * returned. If the lookup determines that the name does not exist
1090 * (negative caching), a status of ENOENT is returned. If the lookup
1091 * fails, a status of zero is returned. If the directory vnode is
1092 * recycled out from under us due to a forced unmount, a status of
1093 * ENOENT is returned.
1095 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is
1096 * unlocked. If we're looking up . an extra ref is taken, but the lock is
1097 * not recursively acquired.
1101 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
1102 struct timespec *tsp, int *ticksp)
1104 struct namecache *ncp;
1106 struct mtx *dvlp, *dvlp2;
1111 cnp->cn_flags &= ~MAKEENTRY;
1116 dvlp = VP2VNODELOCK(dvp);
1118 counter_u64_add(numcalls, 1);
1120 if (cnp->cn_nameptr[0] == '.') {
1121 if (cnp->cn_namelen == 1) {
1123 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .",
1124 dvp, cnp->cn_nameptr);
1125 counter_u64_add(dothits, 1);
1126 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp);
1133 * When we lookup "." we still can be asked to lock it
1136 ltype = cnp->cn_lkflags & LK_TYPE_MASK;
1137 if (ltype != VOP_ISLOCKED(*vpp)) {
1138 if (ltype == LK_EXCLUSIVE) {
1139 vn_lock(*vpp, LK_UPGRADE | LK_RETRY);
1140 if ((*vpp)->v_iflag & VI_DOOMED) {
1141 /* forced unmount */
1147 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY);
1151 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
1152 counter_u64_add(dotdothits, 1);
1156 ncp = dvp->v_cache_dd;
1158 SDT_PROBE3(vfs, namecache, lookup, miss, dvp,
1163 if ((cnp->cn_flags & MAKEENTRY) == 0) {
1164 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) {
1165 if (ncp->nc_dvp != dvp)
1166 panic("dvp %p v_cache_dd %p\n", dvp, ncp);
1167 if (!cache_zap_locked_vnode_kl2(ncp,
1170 MPASS(dvp->v_cache_dd == NULL);
1176 dvp->v_cache_dd = NULL;
1183 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) {
1184 if (ncp->nc_flag & NCF_NEGATIVE)
1190 /* Return failure if negative entry was found. */
1192 goto negative_success;
1193 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..",
1194 dvp, cnp->cn_nameptr, *vpp);
1195 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..",
1197 cache_out_ts(ncp, tsp, ticksp);
1198 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) ==
1199 NCF_DTS && tsp != NULL)
1200 *tsp = ((struct namecache_ts *)ncp)->
1206 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
1207 blp = HASH2BUCKETLOCK(hash);
1210 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
1211 counter_u64_add(numchecks, 1);
1212 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
1213 !bcmp(nc_get_name(ncp), cnp->cn_nameptr, ncp->nc_nlen))
1217 /* We failed to find an entry */
1219 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr,
1221 if ((cnp->cn_flags & MAKEENTRY) == 0) {
1222 counter_u64_add(nummisszap, 1);
1224 counter_u64_add(nummiss, 1);
1229 /* We don't want to have an entry, so dump it */
1230 if ((cnp->cn_flags & MAKEENTRY) == 0) {
1231 counter_u64_add(numposzaps, 1);
1235 /* We found a "positive" match, return the vnode */
1236 if (!(ncp->nc_flag & NCF_NEGATIVE)) {
1237 counter_u64_add(numposhits, 1);
1239 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p",
1240 dvp, cnp->cn_nameptr, *vpp, ncp);
1241 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, nc_get_name(ncp),
1243 cache_out_ts(ncp, tsp, ticksp);
1248 /* We found a negative match, and want to create it, so purge */
1249 if (cnp->cn_nameiop == CREATE) {
1250 counter_u64_add(numnegzaps, 1);
1254 counter_u64_add(numneghits, 1);
1255 cache_negative_hit(ncp);
1256 if (ncp->nc_flag & NCF_WHITE)
1257 cnp->cn_flags |= ISWHITEOUT;
1258 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp,
1260 cache_out_ts(ncp, tsp, ticksp);
1261 cache_lookup_unlock(blp, dvlp);
1266 * On success we return a locked and ref'd vnode as per the lookup
1270 ltype = 0; /* silence gcc warning */
1271 if (cnp->cn_flags & ISDOTDOT) {
1272 ltype = VOP_ISLOCKED(dvp);
1276 cache_lookup_unlock(blp, dvlp);
1277 error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, cnp->cn_thread);
1278 if (cnp->cn_flags & ISDOTDOT) {
1279 vn_lock(dvp, ltype | LK_RETRY);
1280 if (dvp->v_iflag & VI_DOOMED) {
1291 if ((cnp->cn_flags & ISLASTCN) &&
1292 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) {
1293 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup");
1298 cache_lookup_unlock(blp, dvlp);
1303 error = cache_zap_rlocked_bucket(ncp, blp);
1305 error = cache_zap_locked_vnode(ncp, dvp);
1307 zap_and_exit_bucket_fail++;
1308 cache_maybe_yield();
1315 struct celockstate {
1317 struct rwlock *blp[2];
1319 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3));
1320 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2));
1323 cache_celockstate_init(struct celockstate *cel)
1326 bzero(cel, sizeof(*cel));
1330 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp,
1333 struct mtx *vlp1, *vlp2;
1335 MPASS(cel->vlp[0] == NULL);
1336 MPASS(cel->vlp[1] == NULL);
1337 MPASS(cel->vlp[2] == NULL);
1339 MPASS(vp != NULL || dvp != NULL);
1341 vlp1 = VP2VNODELOCK(vp);
1342 vlp2 = VP2VNODELOCK(dvp);
1343 cache_sort(&vlp1, &vlp2);
1354 cache_unlock_vnodes_cel(struct celockstate *cel)
1357 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL);
1359 if (cel->vlp[0] != NULL)
1360 mtx_unlock(cel->vlp[0]);
1361 if (cel->vlp[1] != NULL)
1362 mtx_unlock(cel->vlp[1]);
1363 if (cel->vlp[2] != NULL)
1364 mtx_unlock(cel->vlp[2]);
1368 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp)
1373 cache_assert_vlp_locked(cel->vlp[0]);
1374 cache_assert_vlp_locked(cel->vlp[1]);
1375 MPASS(cel->vlp[2] == NULL);
1377 vlp = VP2VNODELOCK(vp);
1381 if (vlp >= cel->vlp[1]) {
1384 if (mtx_trylock(vlp))
1386 cache_lock_vnodes_cel_3_failures++;
1387 cache_unlock_vnodes_cel(cel);
1388 if (vlp < cel->vlp[0]) {
1390 mtx_lock(cel->vlp[0]);
1391 mtx_lock(cel->vlp[1]);
1393 if (cel->vlp[0] != NULL)
1394 mtx_lock(cel->vlp[0]);
1396 mtx_lock(cel->vlp[1]);
1406 cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1,
1407 struct rwlock *blp2)
1410 MPASS(cel->blp[0] == NULL);
1411 MPASS(cel->blp[1] == NULL);
1413 cache_sort(&blp1, &blp2);
1424 cache_unlock_buckets_cel(struct celockstate *cel)
1427 if (cel->blp[0] != NULL)
1428 rw_wunlock(cel->blp[0]);
1429 rw_wunlock(cel->blp[1]);
1433 * Lock part of the cache affected by the insertion.
1435 * This means vnodelocks for dvp, vp and the relevant bucketlock.
1436 * However, insertion can result in removal of an old entry. In this
1437 * case we have an additional vnode and bucketlock pair to lock. If the
1438 * entry is negative, ncelock is locked instead of the vnode.
1440 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while
1441 * preserving the locking order (smaller address first).
1444 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp,
1447 struct namecache *ncp;
1448 struct rwlock *blps[2];
1450 blps[0] = HASH2BUCKETLOCK(hash);
1453 cache_lock_vnodes_cel(cel, dvp, vp);
1454 if (vp == NULL || vp->v_type != VDIR)
1456 ncp = vp->v_cache_dd;
1459 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
1461 MPASS(ncp->nc_dvp == vp);
1462 blps[1] = NCP2BUCKETLOCK(ncp);
1463 if (ncp->nc_flag & NCF_NEGATIVE)
1465 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp))
1468 * All vnodes got re-locked. Re-validate the state and if
1469 * nothing changed we are done. Otherwise restart.
1471 if (ncp == vp->v_cache_dd &&
1472 (ncp->nc_flag & NCF_ISDOTDOT) != 0 &&
1473 blps[1] == NCP2BUCKETLOCK(ncp) &&
1474 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2])
1476 cache_unlock_vnodes_cel(cel);
1481 cache_lock_buckets_cel(cel, blps[0], blps[1]);
1485 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp,
1488 struct namecache *ncp;
1489 struct rwlock *blps[2];
1491 blps[0] = HASH2BUCKETLOCK(hash);
1494 cache_lock_vnodes_cel(cel, dvp, vp);
1495 ncp = dvp->v_cache_dd;
1498 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
1500 MPASS(ncp->nc_dvp == dvp);
1501 blps[1] = NCP2BUCKETLOCK(ncp);
1502 if (ncp->nc_flag & NCF_NEGATIVE)
1504 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp))
1506 if (ncp == dvp->v_cache_dd &&
1507 (ncp->nc_flag & NCF_ISDOTDOT) != 0 &&
1508 blps[1] == NCP2BUCKETLOCK(ncp) &&
1509 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2])
1511 cache_unlock_vnodes_cel(cel);
1516 cache_lock_buckets_cel(cel, blps[0], blps[1]);
1520 cache_enter_unlock(struct celockstate *cel)
1523 cache_unlock_buckets_cel(cel);
1524 cache_unlock_vnodes_cel(cel);
1528 * Add an entry to the cache.
1531 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp,
1532 struct timespec *tsp, struct timespec *dtsp)
1534 struct celockstate cel;
1535 struct namecache *ncp, *n2, *ndd;
1536 struct namecache_ts *n3;
1537 struct nchashhead *ncpp;
1538 struct neglist *neglist;
1544 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr);
1545 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp,
1546 ("cache_enter: Adding a doomed vnode"));
1547 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp,
1548 ("cache_enter: Doomed vnode used as src"));
1554 * Avoid blowout in namecache entries.
1556 if (numcache >= desiredvnodes * ncsizefactor)
1559 cache_celockstate_init(&cel);
1562 if (cnp->cn_nameptr[0] == '.') {
1563 if (cnp->cn_namelen == 1)
1565 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
1566 len = cnp->cn_namelen;
1567 hash = cache_get_hash(cnp->cn_nameptr, len, dvp);
1568 cache_enter_lock_dd(&cel, dvp, vp, hash);
1570 * If dotdot entry already exists, just retarget it
1571 * to new parent vnode, otherwise continue with new
1572 * namecache entry allocation.
1574 if ((ncp = dvp->v_cache_dd) != NULL &&
1575 ncp->nc_flag & NCF_ISDOTDOT) {
1576 KASSERT(ncp->nc_dvp == dvp,
1577 ("wrong isdotdot parent"));
1579 if (ncp->nc_flag & NCF_NEGATIVE || vp == NULL) {
1580 neglist = NCP2NEGLIST(ncp);
1581 mtx_lock(&ncneg_hot.nl_lock);
1582 mtx_lock(&neglist->nl_lock);
1585 if (!(ncp->nc_flag & NCF_NEGATIVE)) {
1586 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst,
1589 cache_negative_remove(ncp, true);
1592 TAILQ_INSERT_HEAD(&vp->v_cache_dst,
1594 ncp->nc_flag &= ~(NCF_NEGATIVE|NCF_HOTNEGATIVE);
1596 ncp->nc_flag &= ~(NCF_HOTNEGATIVE);
1597 ncp->nc_flag |= NCF_NEGATIVE;
1598 cache_negative_insert(ncp, true);
1601 mtx_unlock(&neglist->nl_lock);
1602 mtx_unlock(&ncneg_hot.nl_lock);
1605 cache_enter_unlock(&cel);
1608 dvp->v_cache_dd = NULL;
1609 cache_enter_unlock(&cel);
1610 cache_celockstate_init(&cel);
1611 SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp);
1612 flag = NCF_ISDOTDOT;
1617 * Calculate the hash key and setup as much of the new
1618 * namecache entry as possible before acquiring the lock.
1620 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL);
1621 ncp->nc_flag = flag;
1624 ncp->nc_flag |= NCF_NEGATIVE;
1627 n3 = (struct namecache_ts *)ncp;
1629 n3->nc_ticks = ticks;
1630 n3->nc_flag |= NCF_TS;
1632 n3->nc_dotdottime = *dtsp;
1633 n3->nc_flag |= NCF_DTS;
1636 len = ncp->nc_nlen = cnp->cn_namelen;
1637 hash = cache_get_hash(cnp->cn_nameptr, len, dvp);
1638 strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1);
1639 cache_enter_lock(&cel, dvp, vp, hash);
1642 * See if this vnode or negative entry is already in the cache
1643 * with this name. This can happen with concurrent lookups of
1644 * the same path name.
1646 ncpp = NCHHASH(hash);
1647 LIST_FOREACH(n2, ncpp, nc_hash) {
1648 if (n2->nc_dvp == dvp &&
1649 n2->nc_nlen == cnp->cn_namelen &&
1650 !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) {
1652 KASSERT((n2->nc_flag & NCF_TS) != 0,
1654 n3 = (struct namecache_ts *)n2;
1656 ((struct namecache_ts *)ncp)->nc_time;
1658 ((struct namecache_ts *)ncp)->nc_ticks;
1661 ((struct namecache_ts *)ncp)->
1663 if (ncp->nc_flag & NCF_NEGATIVE)
1664 mtx_lock(&ncneg_hot.nl_lock);
1665 n3->nc_flag |= NCF_DTS;
1666 if (ncp->nc_flag & NCF_NEGATIVE)
1667 mtx_unlock(&ncneg_hot.nl_lock);
1670 goto out_unlock_free;
1674 if (flag == NCF_ISDOTDOT) {
1676 * See if we are trying to add .. entry, but some other lookup
1677 * has populated v_cache_dd pointer already.
1679 if (dvp->v_cache_dd != NULL)
1680 goto out_unlock_free;
1681 KASSERT(vp == NULL || vp->v_type == VDIR,
1682 ("wrong vnode type %p", vp));
1683 dvp->v_cache_dd = ncp;
1686 atomic_add_rel_long(&numcache, 1);
1688 if (vp->v_type == VDIR) {
1689 if (flag != NCF_ISDOTDOT) {
1691 * For this case, the cache entry maps both the
1692 * directory name in it and the name ".." for the
1693 * directory's parent.
1695 if ((ndd = vp->v_cache_dd) != NULL) {
1696 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0)
1697 cache_zap_locked(ndd, false);
1701 vp->v_cache_dd = ncp;
1704 vp->v_cache_dd = NULL;
1708 if (flag != NCF_ISDOTDOT) {
1709 if (LIST_EMPTY(&dvp->v_cache_src)) {
1711 atomic_add_rel_long(&numcachehv, 1);
1713 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src);
1717 * Insert the new namecache entry into the appropriate chain
1718 * within the cache entries table.
1720 LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
1723 * If the entry is "negative", we place it into the
1724 * "negative" cache queue, otherwise, we place it into the
1725 * destination vnode's cache entries queue.
1728 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst);
1729 SDT_PROBE3(vfs, namecache, enter, done, dvp, nc_get_name(ncp),
1732 if (cnp->cn_flags & ISWHITEOUT)
1733 ncp->nc_flag |= NCF_WHITE;
1734 cache_negative_insert(ncp, false);
1735 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp,
1738 cache_enter_unlock(&cel);
1739 if (numneg * ncnegfactor > numcache)
1740 cache_negative_zap_one();
1744 cache_enter_unlock(&cel);
1750 cache_roundup_2(u_int val)
1754 for (res = 1; res <= val; res <<= 1)
1761 * Name cache initialization, from vfs_init() when we are booting
1764 nchinit(void *dummy __unused)
1768 cache_zone_small = uma_zcreate("S VFS Cache",
1769 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1,
1770 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
1771 cache_zone_small_ts = uma_zcreate("STS VFS Cache",
1772 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1,
1773 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
1774 cache_zone_large = uma_zcreate("L VFS Cache",
1775 sizeof(struct namecache) + NAME_MAX + 1,
1776 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
1777 cache_zone_large_ts = uma_zcreate("LTS VFS Cache",
1778 sizeof(struct namecache_ts) + NAME_MAX + 1,
1779 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
1781 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash);
1782 numbucketlocks = cache_roundup_2(mp_ncpus * 64);
1783 if (numbucketlocks > nchash + 1)
1784 numbucketlocks = nchash + 1;
1785 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE,
1787 for (i = 0; i < numbucketlocks; i++)
1788 rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE);
1789 numvnodelocks = cache_roundup_2(mp_ncpus * 64);
1790 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE,
1792 for (i = 0; i < numvnodelocks; i++)
1793 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE);
1794 ncpurgeminvnodes = numbucketlocks;
1797 neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE,
1799 for (i = 0; i < numneglists; i++) {
1800 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF);
1801 TAILQ_INIT(&neglists[i].nl_list);
1803 mtx_init(&ncneg_hot.nl_lock, "ncneglh", NULL, MTX_DEF);
1804 TAILQ_INIT(&ncneg_hot.nl_list);
1806 numcalls = counter_u64_alloc(M_WAITOK);
1807 dothits = counter_u64_alloc(M_WAITOK);
1808 dotdothits = counter_u64_alloc(M_WAITOK);
1809 numchecks = counter_u64_alloc(M_WAITOK);
1810 nummiss = counter_u64_alloc(M_WAITOK);
1811 nummisszap = counter_u64_alloc(M_WAITOK);
1812 numposzaps = counter_u64_alloc(M_WAITOK);
1813 numposhits = counter_u64_alloc(M_WAITOK);
1814 numnegzaps = counter_u64_alloc(M_WAITOK);
1815 numneghits = counter_u64_alloc(M_WAITOK);
1816 numfullpathcalls = counter_u64_alloc(M_WAITOK);
1817 numfullpathfail1 = counter_u64_alloc(M_WAITOK);
1818 numfullpathfail2 = counter_u64_alloc(M_WAITOK);
1819 numfullpathfail4 = counter_u64_alloc(M_WAITOK);
1820 numfullpathfound = counter_u64_alloc(M_WAITOK);
1822 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
1825 cache_changesize(int newmaxvnodes)
1827 struct nchashhead *new_nchashtbl, *old_nchashtbl;
1828 u_long new_nchash, old_nchash;
1829 struct namecache *ncp;
1833 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2);
1834 if (newmaxvnodes < numbucketlocks)
1835 newmaxvnodes = numbucketlocks;
1837 new_nchashtbl = hashinit(newmaxvnodes, M_VFSCACHE, &new_nchash);
1838 /* If same hash table size, nothing to do */
1839 if (nchash == new_nchash) {
1840 free(new_nchashtbl, M_VFSCACHE);
1844 * Move everything from the old hash table to the new table.
1845 * None of the namecache entries in the table can be removed
1846 * because to do so, they have to be removed from the hash table.
1848 cache_lock_all_vnodes();
1849 cache_lock_all_buckets();
1850 old_nchashtbl = nchashtbl;
1851 old_nchash = nchash;
1852 nchashtbl = new_nchashtbl;
1853 nchash = new_nchash;
1854 for (i = 0; i <= old_nchash; i++) {
1855 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) {
1856 hash = cache_get_hash(nc_get_name(ncp), ncp->nc_nlen,
1858 LIST_REMOVE(ncp, nc_hash);
1859 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash);
1862 cache_unlock_all_buckets();
1863 cache_unlock_all_vnodes();
1864 free(old_nchashtbl, M_VFSCACHE);
1868 * Invalidate all entries to a particular vnode.
1871 cache_purge(struct vnode *vp)
1873 TAILQ_HEAD(, namecache) ncps;
1874 struct namecache *ncp, *nnp;
1875 struct mtx *vlp, *vlp2;
1877 CTR1(KTR_VFS, "cache_purge(%p)", vp);
1878 SDT_PROBE1(vfs, namecache, purge, done, vp);
1879 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) &&
1880 vp->v_cache_dd == NULL)
1883 vlp = VP2VNODELOCK(vp);
1887 while (!LIST_EMPTY(&vp->v_cache_src)) {
1888 ncp = LIST_FIRST(&vp->v_cache_src);
1889 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
1891 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
1893 while (!TAILQ_EMPTY(&vp->v_cache_dst)) {
1894 ncp = TAILQ_FIRST(&vp->v_cache_dst);
1895 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
1897 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
1899 ncp = vp->v_cache_dd;
1901 KASSERT(ncp->nc_flag & NCF_ISDOTDOT,
1902 ("lost dotdot link"));
1903 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
1905 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
1907 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge"));
1911 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) {
1917 * Invalidate all negative entries for a particular directory vnode.
1920 cache_purge_negative(struct vnode *vp)
1922 TAILQ_HEAD(, namecache) ncps;
1923 struct namecache *ncp, *nnp;
1926 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp);
1927 SDT_PROBE1(vfs, namecache, purge_negative, done, vp);
1929 vlp = VP2VNODELOCK(vp);
1931 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) {
1932 if (!(ncp->nc_flag & NCF_NEGATIVE))
1934 cache_zap_negative_locked_vnode_kl(ncp, vp);
1935 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
1938 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) {
1944 * Flush all entries referencing a particular filesystem.
1947 cache_purgevfs(struct mount *mp, bool force)
1949 TAILQ_HEAD(, namecache) ncps;
1950 struct mtx *vlp1, *vlp2;
1952 struct nchashhead *bucket;
1953 struct namecache *ncp, *nnp;
1954 u_long i, j, n_nchash;
1957 /* Scan hash tables for applicable entries */
1958 SDT_PROBE1(vfs, namecache, purgevfs, done, mp);
1959 if (!force && mp->mnt_nvnodelistsize <= ncpurgeminvnodes)
1962 n_nchash = nchash + 1;
1964 for (i = 0; i < numbucketlocks; i++) {
1965 blp = (struct rwlock *)&bucketlocks[i];
1967 for (j = i; j < n_nchash; j += numbucketlocks) {
1969 bucket = &nchashtbl[j];
1970 LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) {
1971 cache_assert_bucket_locked(ncp, RA_WLOCKED);
1972 if (ncp->nc_dvp->v_mount != mp)
1974 error = cache_zap_wlocked_bucket_kl(ncp, blp,
1978 TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst);
1982 if (vlp1 == NULL && vlp2 == NULL)
1983 cache_maybe_yield();
1990 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) {
1996 * Perform canonical checks and cache lookup and pass on to filesystem
1997 * through the vop_cachedlookup only if needed.
2001 vfs_cache_lookup(struct vop_lookup_args *ap)
2005 struct vnode **vpp = ap->a_vpp;
2006 struct componentname *cnp = ap->a_cnp;
2007 struct ucred *cred = cnp->cn_cred;
2008 int flags = cnp->cn_flags;
2009 struct thread *td = cnp->cn_thread;
2014 if (dvp->v_type != VDIR)
2017 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
2018 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
2021 error = VOP_ACCESS(dvp, VEXEC, cred, td);
2025 error = cache_lookup(dvp, vpp, cnp, NULL, NULL);
2027 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
2034 * XXX All of these sysctls would probably be more productive dead.
2036 static int disablecwd;
2037 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0,
2038 "Disable the getcwd syscall");
2040 /* Implementation of the getcwd syscall. */
2042 sys___getcwd(struct thread *td, struct __getcwd_args *uap)
2045 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen,
2050 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, u_int buflen,
2054 struct filedesc *fdp;
2055 struct vnode *cdir, *rdir;
2062 if (buflen > path_max)
2065 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK);
2066 fdp = td->td_proc->p_fd;
2067 FILEDESC_SLOCK(fdp);
2068 cdir = fdp->fd_cdir;
2070 rdir = fdp->fd_rdir;
2072 FILEDESC_SUNLOCK(fdp);
2073 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen);
2078 if (bufseg == UIO_SYSSPACE)
2079 bcopy(bp, buf, strlen(bp) + 1);
2081 error = copyout(bp, buf, strlen(bp) + 1);
2083 if (KTRPOINT(curthread, KTR_NAMEI))
2087 free(tmpbuf, M_TEMP);
2092 * Thus begins the fullpath magic.
2095 static int disablefullpath;
2096 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0,
2097 "Disable the vn_fullpath function");
2100 * Retrieve the full filesystem path that correspond to a vnode from the name
2101 * cache (if available)
2104 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf)
2107 struct filedesc *fdp;
2111 if (disablefullpath)
2116 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
2117 fdp = td->td_proc->p_fd;
2118 FILEDESC_SLOCK(fdp);
2119 rdir = fdp->fd_rdir;
2121 FILEDESC_SUNLOCK(fdp);
2122 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN);
2133 * This function is similar to vn_fullpath, but it attempts to lookup the
2134 * pathname relative to the global root mount point. This is required for the
2135 * auditing sub-system, as audited pathnames must be absolute, relative to the
2136 * global root mount point.
2139 vn_fullpath_global(struct thread *td, struct vnode *vn,
2140 char **retbuf, char **freebuf)
2145 if (disablefullpath)
2149 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
2150 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN);
2159 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen)
2162 struct namecache *ncp;
2166 vlp = VP2VNODELOCK(*vp);
2168 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) {
2169 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
2173 if (*buflen < ncp->nc_nlen) {
2176 counter_u64_add(numfullpathfail4, 1);
2178 SDT_PROBE3(vfs, namecache, fullpath, return, error,
2182 *buflen -= ncp->nc_nlen;
2183 memcpy(buf + *buflen, nc_get_name(ncp), ncp->nc_nlen);
2184 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp,
2185 nc_get_name(ncp), vp);
2193 SDT_PROBE1(vfs, namecache, fullpath, miss, vp);
2196 vn_lock(*vp, LK_SHARED | LK_RETRY);
2197 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen);
2200 counter_u64_add(numfullpathfail2, 1);
2201 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL);
2206 if (dvp->v_iflag & VI_DOOMED) {
2207 /* forced unmount */
2210 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL);
2214 * *vp has its use count incremented still.
2221 * The magic behind kern___getcwd() and vn_fullpath().
2224 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
2225 char *buf, char **retbuf, u_int buflen)
2227 int error, slash_prefixed;
2228 #ifdef KDTRACE_HOOKS
2229 struct vnode *startvp = vp;
2238 SDT_PROBE1(vfs, namecache, fullpath, entry, vp);
2239 counter_u64_add(numfullpathcalls, 1);
2241 if (vp->v_type != VDIR) {
2242 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen);
2249 buf[--buflen] = '/';
2252 while (vp != rdir && vp != rootvnode) {
2254 * The vp vnode must be already fully constructed,
2255 * since it is either found in namecache or obtained
2256 * from VOP_VPTOCNP(). We may test for VV_ROOT safely
2257 * without obtaining the vnode lock.
2259 if ((vp->v_vflag & VV_ROOT) != 0) {
2260 vn_lock(vp, LK_RETRY | LK_SHARED);
2263 * With the vnode locked, check for races with
2264 * unmount, forced or not. Note that we
2265 * already verified that vp is not equal to
2266 * the root vnode, which means that
2267 * mnt_vnodecovered can be NULL only for the
2270 if ((vp->v_iflag & VI_DOOMED) != 0 ||
2271 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL ||
2272 vp1->v_mountedhere != vp->v_mount) {
2275 SDT_PROBE3(vfs, namecache, fullpath, return,
2285 if (vp->v_type != VDIR) {
2287 counter_u64_add(numfullpathfail1, 1);
2289 SDT_PROBE3(vfs, namecache, fullpath, return,
2293 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen);
2299 SDT_PROBE3(vfs, namecache, fullpath, return, error,
2303 buf[--buflen] = '/';
2308 if (!slash_prefixed) {
2311 counter_u64_add(numfullpathfail4, 1);
2312 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM,
2316 buf[--buflen] = '/';
2318 counter_u64_add(numfullpathfound, 1);
2321 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen);
2322 *retbuf = buf + buflen;
2327 vn_dir_dd_ino(struct vnode *vp)
2329 struct namecache *ncp;
2333 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino");
2334 vlp = VP2VNODELOCK(vp);
2336 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) {
2337 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0)
2342 if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread))
2351 vn_commname(struct vnode *vp, char *buf, u_int buflen)
2353 struct namecache *ncp;
2357 vlp = VP2VNODELOCK(vp);
2359 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst)
2360 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
2366 l = min(ncp->nc_nlen, buflen - 1);
2367 memcpy(buf, nc_get_name(ncp), l);
2373 /* ABI compat shims for old kernel modules. */
2376 void cache_enter(struct vnode *dvp, struct vnode *vp,
2377 struct componentname *cnp);
2380 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp)
2383 cache_enter_time(dvp, vp, cnp, NULL, NULL);
2387 * This function updates path string to vnode's full global path
2388 * and checks the size of the new path string against the pathlen argument.
2390 * Requires a locked, referenced vnode.
2391 * Vnode is re-locked on success or ENODEV, otherwise unlocked.
2393 * If sysctl debug.disablefullpath is set, ENODEV is returned,
2394 * vnode is left locked and path remain untouched.
2396 * If vp is a directory, the call to vn_fullpath_global() always succeeds
2397 * because it falls back to the ".." lookup if the namecache lookup fails.
2400 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path,
2403 struct nameidata nd;
2408 ASSERT_VOP_ELOCKED(vp, __func__);
2410 /* Return ENODEV if sysctl debug.disablefullpath==1 */
2411 if (disablefullpath)
2414 /* Construct global filesystem path from vp. */
2416 error = vn_fullpath_global(td, vp, &rpath, &fbuf);
2423 if (strlen(rpath) >= pathlen) {
2425 error = ENAMETOOLONG;
2430 * Re-lookup the vnode by path to detect a possible rename.
2431 * As a side effect, the vnode is relocked.
2432 * If vnode was renamed, return ENOENT.
2434 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1,
2435 UIO_SYSSPACE, path, td);
2441 NDFREE(&nd, NDF_ONLY_PNBUF);
2445 strcpy(path, rpath);