FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_cache.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1989, 1993, 1995
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Poul-Henning Kamp of the FreeBSD Project.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95
35 */
36
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD: releng/12.0/sys/kern/vfs_cache.c 335437 2018-06-20 08:34:29Z bz $");
39
40 #include "opt_ddb.h"
41 #include "opt_ktrace.h"
42
43 #include <sys/param.h>
44 #include <sys/systm.h>
45 #include <sys/counter.h>
46 #include <sys/filedesc.h>
47 #include <sys/fnv_hash.h>
48 #include <sys/kernel.h>
49 #include <sys/lock.h>
50 #include <sys/malloc.h>
51 #include <sys/fcntl.h>
52 #include <sys/mount.h>
53 #include <sys/namei.h>
54 #include <sys/proc.h>
55 #include <sys/rwlock.h>
56 #include <sys/sdt.h>
57 #include <sys/smp.h>
58 #include <sys/syscallsubr.h>
59 #include <sys/sysctl.h>
60 #include <sys/sysproto.h>
61 #include <sys/vnode.h>
62 #ifdef KTRACE
63 #include <sys/ktrace.h>
64 #endif
65
66 #ifdef DDB
67 #include <ddb/ddb.h>
68 #endif
69
70 #include <vm/uma.h>
71
72 SDT_PROVIDER_DECLARE(vfs);
73 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *",
74 "struct vnode *");
75 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *",
76 "char *");
77 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *");
78 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *",
79 "char *", "struct vnode *");
80 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *");
81 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int",
82 "struct vnode *", "char *");
83 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *",
84 "struct vnode *");
85 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative,
86 "struct vnode *", "char *");
87 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *",
88 "char *");
89 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *");
90 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *");
91 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *");
92 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *",
93 "struct vnode *");
94 SDT_PROBE_DEFINE3(vfs, namecache, zap_negative, done, "struct vnode *",
95 "char *", "int");
96 SDT_PROBE_DEFINE3(vfs, namecache, shrink_negative, done, "struct vnode *",
97 "char *", "int");
98
99 /*
100 * This structure describes the elements in the cache of recent
101 * names looked up by namei.
102 */
103
104 struct namecache {
105 LIST_ENTRY(namecache) nc_hash; /* hash chain */
106 LIST_ENTRY(namecache) nc_src; /* source vnode list */
107 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */
108 struct vnode *nc_dvp; /* vnode of parent of name */
109 union {
110 struct vnode *nu_vp; /* vnode the name refers to */
111 u_int nu_neghits; /* negative entry hits */
112 } n_un;
113 u_char nc_flag; /* flag bits */
114 u_char nc_nlen; /* length of name */
115 char nc_name[0]; /* segment name + nul */
116 };
117
118 /*
119 * struct namecache_ts repeats struct namecache layout up to the
120 * nc_nlen member.
121 * struct namecache_ts is used in place of struct namecache when time(s) need
122 * to be stored. The nc_dotdottime field is used when a cache entry is mapping
123 * both a non-dotdot directory name plus dotdot for the directory's
124 * parent.
125 */
126 struct namecache_ts {
127 struct timespec nc_time; /* timespec provided by fs */
128 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */
129 int nc_ticks; /* ticks value when entry was added */
130 struct namecache nc_nc;
131 };
132
133 #define nc_vp n_un.nu_vp
134 #define nc_neghits n_un.nu_neghits
135
136 /*
137 * Flags in namecache.nc_flag
138 */
139 #define NCF_WHITE 0x01
140 #define NCF_ISDOTDOT 0x02
141 #define NCF_TS 0x04
142 #define NCF_DTS 0x08
143 #define NCF_DVDROP 0x10
144 #define NCF_NEGATIVE 0x20
145 #define NCF_HOTNEGATIVE 0x40
146
147 /*
148 * Name caching works as follows:
149 *
150 * Names found by directory scans are retained in a cache
151 * for future reference. It is managed LRU, so frequently
152 * used names will hang around. Cache is indexed by hash value
153 * obtained from (vp, name) where vp refers to the directory
154 * containing name.
155 *
156 * If it is a "negative" entry, (i.e. for a name that is known NOT to
157 * exist) the vnode pointer will be NULL.
158 *
159 * Upon reaching the last segment of a path, if the reference
160 * is for DELETE, or NOCACHE is set (rewrite), and the
161 * name is located in the cache, it will be dropped.
162 *
163 * These locks are used (in the order in which they can be taken):
164 * NAME TYPE ROLE
165 * vnodelock mtx vnode lists and v_cache_dd field protection
166 * bucketlock rwlock for access to given set of hash buckets
167 * neglist mtx negative entry LRU management
168 *
169 * Additionally, ncneg_shrink_lock mtx is used to have at most one thread
170 * shrinking the LRU list.
171 *
172 * It is legal to take multiple vnodelock and bucketlock locks. The locking
173 * order is lower address first. Both are recursive.
174 *
175 * "." lookups are lockless.
176 *
177 * ".." and vnode -> name lookups require vnodelock.
178 *
179 * name -> vnode lookup requires the relevant bucketlock to be held for reading.
180 *
181 * Insertions and removals of entries require involved vnodes and bucketlocks
182 * to be write-locked to prevent other threads from seeing the entry.
183 *
184 * Some lookups result in removal of the found entry (e.g. getting rid of a
185 * negative entry with the intent to create a positive one), which poses a
186 * problem when multiple threads reach the state. Similarly, two different
187 * threads can purge two different vnodes and try to remove the same name.
188 *
189 * If the already held vnode lock is lower than the second required lock, we
190 * can just take the other lock. However, in the opposite case, this could
191 * deadlock. As such, this is resolved by trylocking and if that fails unlocking
192 * the first node, locking everything in order and revalidating the state.
193 */
194
195 /*
196 * Structures associated with name caching.
197 */
198 #define NCHHASH(hash) \
199 (&nchashtbl[(hash) & nchash])
200 static __read_mostly LIST_HEAD(nchashhead, namecache) *nchashtbl;/* Hash Table */
201 static u_long __read_mostly nchash; /* size of hash table */
202 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0,
203 "Size of namecache hash table");
204 static u_long __read_mostly ncnegfactor = 12; /* ratio of negative entries */
205 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0,
206 "Ratio of negative namecache entries");
207 static u_long __exclusive_cache_line numneg; /* number of negative entries allocated */
208 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0,
209 "Number of negative entries in namecache");
210 static u_long __exclusive_cache_line numcache;/* number of cache entries allocated */
211 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0,
212 "Number of namecache entries");
213 static u_long __exclusive_cache_line numcachehv;/* number of cache entries with vnodes held */
214 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0,
215 "Number of namecache entries with vnodes held");
216 u_int __read_mostly ncsizefactor = 2;
217 SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0,
218 "Size factor for namecache");
219 static u_int __read_mostly ncpurgeminvnodes;
220 SYSCTL_UINT(_vfs, OID_AUTO, ncpurgeminvnodes, CTLFLAG_RW, &ncpurgeminvnodes, 0,
221 "Number of vnodes below which purgevfs ignores the request");
222 static u_int __read_mostly ncneghitsrequeue = 8;
223 SYSCTL_UINT(_vfs, OID_AUTO, ncneghitsrequeue, CTLFLAG_RW, &ncneghitsrequeue, 0,
224 "Number of hits to requeue a negative entry in the LRU list");
225
226 struct nchstats nchstats; /* cache effectiveness statistics */
227
228 static struct mtx ncneg_shrink_lock;
229 static int shrink_list_turn;
230
231 struct neglist {
232 struct mtx nl_lock;
233 TAILQ_HEAD(, namecache) nl_list;
234 } __aligned(CACHE_LINE_SIZE);
235
236 static struct neglist __read_mostly *neglists;
237 static struct neglist ncneg_hot;
238
239 #define numneglists (ncneghash + 1)
240 static u_int __read_mostly ncneghash;
241 static inline struct neglist *
242 NCP2NEGLIST(struct namecache *ncp)
243 {
244
245 return (&neglists[(((uintptr_t)(ncp) >> 8) & ncneghash)]);
246 }
247
248 #define numbucketlocks (ncbuckethash + 1)
249 static u_int __read_mostly ncbuckethash;
250 static struct rwlock_padalign __read_mostly *bucketlocks;
251 #define HASH2BUCKETLOCK(hash) \
252 ((struct rwlock *)(&bucketlocks[((hash) & ncbuckethash)]))
253
254 #define numvnodelocks (ncvnodehash + 1)
255 static u_int __read_mostly ncvnodehash;
256 static struct mtx __read_mostly *vnodelocks;
257 static inline struct mtx *
258 VP2VNODELOCK(struct vnode *vp)
259 {
260
261 return (&vnodelocks[(((uintptr_t)(vp) >> 8) & ncvnodehash)]);
262 }
263
264 /*
265 * UMA zones for the VFS cache.
266 *
267 * The small cache is used for entries with short names, which are the
268 * most common. The large cache is used for entries which are too big to
269 * fit in the small cache.
270 */
271 static uma_zone_t __read_mostly cache_zone_small;
272 static uma_zone_t __read_mostly cache_zone_small_ts;
273 static uma_zone_t __read_mostly cache_zone_large;
274 static uma_zone_t __read_mostly cache_zone_large_ts;
275
276 #define CACHE_PATH_CUTOFF 35
277
278 static struct namecache *
279 cache_alloc(int len, int ts)
280 {
281 struct namecache_ts *ncp_ts;
282 struct namecache *ncp;
283
284 if (__predict_false(ts)) {
285 if (len <= CACHE_PATH_CUTOFF)
286 ncp_ts = uma_zalloc(cache_zone_small_ts, M_WAITOK);
287 else
288 ncp_ts = uma_zalloc(cache_zone_large_ts, M_WAITOK);
289 ncp = &ncp_ts->nc_nc;
290 } else {
291 if (len <= CACHE_PATH_CUTOFF)
292 ncp = uma_zalloc(cache_zone_small, M_WAITOK);
293 else
294 ncp = uma_zalloc(cache_zone_large, M_WAITOK);
295 }
296 return (ncp);
297 }
298
299 static void
300 cache_free(struct namecache *ncp)
301 {
302 struct namecache_ts *ncp_ts;
303
304 if (ncp == NULL)
305 return;
306 if ((ncp->nc_flag & NCF_DVDROP) != 0)
307 vdrop(ncp->nc_dvp);
308 if (__predict_false(ncp->nc_flag & NCF_TS)) {
309 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc);
310 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF)
311 uma_zfree(cache_zone_small_ts, ncp_ts);
312 else
313 uma_zfree(cache_zone_large_ts, ncp_ts);
314 } else {
315 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF)
316 uma_zfree(cache_zone_small, ncp);
317 else
318 uma_zfree(cache_zone_large, ncp);
319 }
320 }
321
322 static void
323 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp)
324 {
325 struct namecache_ts *ncp_ts;
326
327 KASSERT((ncp->nc_flag & NCF_TS) != 0 ||
328 (tsp == NULL && ticksp == NULL),
329 ("No NCF_TS"));
330
331 if (tsp == NULL && ticksp == NULL)
332 return;
333
334 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc);
335 if (tsp != NULL)
336 *tsp = ncp_ts->nc_time;
337 if (ticksp != NULL)
338 *ticksp = ncp_ts->nc_ticks;
339 }
340
341 static int __read_mostly doingcache = 1; /* 1 => enable the cache */
342 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0,
343 "VFS namecache enabled");
344
345 /* Export size information to userland */
346 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR,
347 sizeof(struct namecache), "sizeof(struct namecache)");
348
349 /*
350 * The new name cache statistics
351 */
352 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0,
353 "Name cache statistics");
354 #define STATNODE_ULONG(name, descr) \
355 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr);
356 #define STATNODE_COUNTER(name, descr) \
357 static counter_u64_t __read_mostly name; \
358 SYSCTL_COUNTER_U64(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, descr);
359 STATNODE_ULONG(numneg, "Number of negative cache entries");
360 STATNODE_ULONG(numcache, "Number of cache entries");
361 STATNODE_COUNTER(numcalls, "Number of cache lookups");
362 STATNODE_COUNTER(dothits, "Number of '.' hits");
363 STATNODE_COUNTER(dotdothits, "Number of '..' hits");
364 STATNODE_COUNTER(numchecks, "Number of checks in lookup");
365 STATNODE_COUNTER(nummiss, "Number of cache misses");
366 STATNODE_COUNTER(nummisszap, "Number of cache misses we do not want to cache");
367 STATNODE_COUNTER(numposzaps,
368 "Number of cache hits (positive) we do not want to cache");
369 STATNODE_COUNTER(numposhits, "Number of cache hits (positive)");
370 STATNODE_COUNTER(numnegzaps,
371 "Number of cache hits (negative) we do not want to cache");
372 STATNODE_COUNTER(numneghits, "Number of cache hits (negative)");
373 /* These count for kern___getcwd(), too. */
374 STATNODE_COUNTER(numfullpathcalls, "Number of fullpath search calls");
375 STATNODE_COUNTER(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)");
376 STATNODE_COUNTER(numfullpathfail2,
377 "Number of fullpath search errors (VOP_VPTOCNP failures)");
378 STATNODE_COUNTER(numfullpathfail4, "Number of fullpath search errors (ENOMEM)");
379 STATNODE_COUNTER(numfullpathfound, "Number of successful fullpath calls");
380 static long zap_and_exit_bucket_fail; STATNODE_ULONG(zap_and_exit_bucket_fail,
381 "Number of times zap_and_exit failed to lock");
382 static long cache_lock_vnodes_cel_3_failures;
383 STATNODE_ULONG(cache_lock_vnodes_cel_3_failures,
384 "Number of times 3-way vnode locking failed");
385
386 static void cache_zap_locked(struct namecache *ncp, bool neg_locked);
387 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
388 char *buf, char **retbuf, u_int buflen);
389
390 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries");
391
392 static int cache_yield;
393 SYSCTL_INT(_vfs_cache, OID_AUTO, yield, CTLFLAG_RD, &cache_yield, 0,
394 "Number of times cache called yield");
395
396 static void
397 cache_maybe_yield(void)
398 {
399
400 if (should_yield()) {
401 cache_yield++;
402 kern_yield(PRI_USER);
403 }
404 }
405
406 static inline void
407 cache_assert_vlp_locked(struct mtx *vlp)
408 {
409
410 if (vlp != NULL)
411 mtx_assert(vlp, MA_OWNED);
412 }
413
414 static inline void
415 cache_assert_vnode_locked(struct vnode *vp)
416 {
417 struct mtx *vlp;
418
419 vlp = VP2VNODELOCK(vp);
420 cache_assert_vlp_locked(vlp);
421 }
422
423 static uint32_t
424 cache_get_hash(char *name, u_char len, struct vnode *dvp)
425 {
426 uint32_t hash;
427
428 hash = fnv_32_buf(name, len, FNV1_32_INIT);
429 hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
430 return (hash);
431 }
432
433 static inline struct rwlock *
434 NCP2BUCKETLOCK(struct namecache *ncp)
435 {
436 uint32_t hash;
437
438 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen, ncp->nc_dvp);
439 return (HASH2BUCKETLOCK(hash));
440 }
441
442 #ifdef INVARIANTS
443 static void
444 cache_assert_bucket_locked(struct namecache *ncp, int mode)
445 {
446 struct rwlock *blp;
447
448 blp = NCP2BUCKETLOCK(ncp);
449 rw_assert(blp, mode);
450 }
451 #else
452 #define cache_assert_bucket_locked(x, y) do { } while (0)
453 #endif
454
455 #define cache_sort(x, y) _cache_sort((void **)(x), (void **)(y))
456 static void
457 _cache_sort(void **p1, void **p2)
458 {
459 void *tmp;
460
461 if (*p1 > *p2) {
462 tmp = *p2;
463 *p2 = *p1;
464 *p1 = tmp;
465 }
466 }
467
468 static void
469 cache_lock_all_buckets(void)
470 {
471 u_int i;
472
473 for (i = 0; i < numbucketlocks; i++)
474 rw_wlock(&bucketlocks[i]);
475 }
476
477 static void
478 cache_unlock_all_buckets(void)
479 {
480 u_int i;
481
482 for (i = 0; i < numbucketlocks; i++)
483 rw_wunlock(&bucketlocks[i]);
484 }
485
486 static void
487 cache_lock_all_vnodes(void)
488 {
489 u_int i;
490
491 for (i = 0; i < numvnodelocks; i++)
492 mtx_lock(&vnodelocks[i]);
493 }
494
495 static void
496 cache_unlock_all_vnodes(void)
497 {
498 u_int i;
499
500 for (i = 0; i < numvnodelocks; i++)
501 mtx_unlock(&vnodelocks[i]);
502 }
503
504 static int
505 cache_trylock_vnodes(struct mtx *vlp1, struct mtx *vlp2)
506 {
507
508 cache_sort(&vlp1, &vlp2);
509 MPASS(vlp2 != NULL);
510
511 if (vlp1 != NULL) {
512 if (!mtx_trylock(vlp1))
513 return (EAGAIN);
514 }
515 if (!mtx_trylock(vlp2)) {
516 if (vlp1 != NULL)
517 mtx_unlock(vlp1);
518 return (EAGAIN);
519 }
520
521 return (0);
522 }
523
524 static void
525 cache_unlock_vnodes(struct mtx *vlp1, struct mtx *vlp2)
526 {
527
528 MPASS(vlp1 != NULL || vlp2 != NULL);
529
530 if (vlp1 != NULL)
531 mtx_unlock(vlp1);
532 if (vlp2 != NULL)
533 mtx_unlock(vlp2);
534 }
535
536 static int
537 sysctl_nchstats(SYSCTL_HANDLER_ARGS)
538 {
539 struct nchstats snap;
540
541 if (req->oldptr == NULL)
542 return (SYSCTL_OUT(req, 0, sizeof(snap)));
543
544 snap = nchstats;
545 snap.ncs_goodhits = counter_u64_fetch(numposhits);
546 snap.ncs_neghits = counter_u64_fetch(numneghits);
547 snap.ncs_badhits = counter_u64_fetch(numposzaps) +
548 counter_u64_fetch(numnegzaps);
549 snap.ncs_miss = counter_u64_fetch(nummisszap) +
550 counter_u64_fetch(nummiss);
551
552 return (SYSCTL_OUT(req, &snap, sizeof(snap)));
553 }
554 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE | CTLFLAG_RD |
555 CTLFLAG_MPSAFE, 0, 0, sysctl_nchstats, "LU",
556 "VFS cache effectiveness statistics");
557
558 #ifdef DIAGNOSTIC
559 /*
560 * Grab an atomic snapshot of the name cache hash chain lengths
561 */
562 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL,
563 "hash table stats");
564
565 static int
566 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS)
567 {
568 struct nchashhead *ncpp;
569 struct namecache *ncp;
570 int i, error, n_nchash, *cntbuf;
571
572 retry:
573 n_nchash = nchash + 1; /* nchash is max index, not count */
574 if (req->oldptr == NULL)
575 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int));
576 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK);
577 cache_lock_all_buckets();
578 if (n_nchash != nchash + 1) {
579 cache_unlock_all_buckets();
580 free(cntbuf, M_TEMP);
581 goto retry;
582 }
583 /* Scan hash tables counting entries */
584 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++)
585 LIST_FOREACH(ncp, ncpp, nc_hash)
586 cntbuf[i]++;
587 cache_unlock_all_buckets();
588 for (error = 0, i = 0; i < n_nchash; i++)
589 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0)
590 break;
591 free(cntbuf, M_TEMP);
592 return (error);
593 }
594 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD|
595 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int",
596 "nchash chain lengths");
597
598 static int
599 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS)
600 {
601 int error;
602 struct nchashhead *ncpp;
603 struct namecache *ncp;
604 int n_nchash;
605 int count, maxlength, used, pct;
606
607 if (!req->oldptr)
608 return SYSCTL_OUT(req, 0, 4 * sizeof(int));
609
610 cache_lock_all_buckets();
611 n_nchash = nchash + 1; /* nchash is max index, not count */
612 used = 0;
613 maxlength = 0;
614
615 /* Scan hash tables for applicable entries */
616 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
617 count = 0;
618 LIST_FOREACH(ncp, ncpp, nc_hash) {
619 count++;
620 }
621 if (count)
622 used++;
623 if (maxlength < count)
624 maxlength = count;
625 }
626 n_nchash = nchash + 1;
627 cache_unlock_all_buckets();
628 pct = (used * 100) / (n_nchash / 100);
629 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash));
630 if (error)
631 return (error);
632 error = SYSCTL_OUT(req, &used, sizeof(used));
633 if (error)
634 return (error);
635 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength));
636 if (error)
637 return (error);
638 error = SYSCTL_OUT(req, &pct, sizeof(pct));
639 if (error)
640 return (error);
641 return (0);
642 }
643 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD|
644 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I",
645 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)");
646 #endif
647
648 /*
649 * Negative entries management
650 *
651 * A variation of LRU scheme is used. New entries are hashed into one of
652 * numneglists cold lists. Entries get promoted to the hot list on first hit.
653 * Partial LRU for the hot list is maintained by requeueing them every
654 * ncneghitsrequeue hits.
655 *
656 * The shrinker will demote hot list head and evict from the cold list in a
657 * round-robin manner.
658 */
659 static void
660 cache_negative_hit(struct namecache *ncp)
661 {
662 struct neglist *neglist;
663 u_int hits;
664
665 MPASS(ncp->nc_flag & NCF_NEGATIVE);
666 hits = atomic_fetchadd_int(&ncp->nc_neghits, 1);
667 if (ncp->nc_flag & NCF_HOTNEGATIVE) {
668 if ((hits % ncneghitsrequeue) != 0)
669 return;
670 mtx_lock(&ncneg_hot.nl_lock);
671 if (ncp->nc_flag & NCF_HOTNEGATIVE) {
672 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst);
673 TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst);
674 mtx_unlock(&ncneg_hot.nl_lock);
675 return;
676 }
677 /*
678 * The shrinker cleared the flag and removed the entry from
679 * the hot list. Put it back.
680 */
681 } else {
682 mtx_lock(&ncneg_hot.nl_lock);
683 }
684 neglist = NCP2NEGLIST(ncp);
685 mtx_lock(&neglist->nl_lock);
686 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) {
687 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst);
688 TAILQ_INSERT_TAIL(&ncneg_hot.nl_list, ncp, nc_dst);
689 ncp->nc_flag |= NCF_HOTNEGATIVE;
690 }
691 mtx_unlock(&neglist->nl_lock);
692 mtx_unlock(&ncneg_hot.nl_lock);
693 }
694
695 static void
696 cache_negative_insert(struct namecache *ncp, bool neg_locked)
697 {
698 struct neglist *neglist;
699
700 MPASS(ncp->nc_flag & NCF_NEGATIVE);
701 cache_assert_bucket_locked(ncp, RA_WLOCKED);
702 neglist = NCP2NEGLIST(ncp);
703 if (!neg_locked) {
704 mtx_lock(&neglist->nl_lock);
705 } else {
706 mtx_assert(&neglist->nl_lock, MA_OWNED);
707 }
708 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst);
709 if (!neg_locked)
710 mtx_unlock(&neglist->nl_lock);
711 atomic_add_rel_long(&numneg, 1);
712 }
713
714 static void
715 cache_negative_remove(struct namecache *ncp, bool neg_locked)
716 {
717 struct neglist *neglist;
718 bool hot_locked = false;
719 bool list_locked = false;
720
721 MPASS(ncp->nc_flag & NCF_NEGATIVE);
722 cache_assert_bucket_locked(ncp, RA_WLOCKED);
723 neglist = NCP2NEGLIST(ncp);
724 if (!neg_locked) {
725 if (ncp->nc_flag & NCF_HOTNEGATIVE) {
726 hot_locked = true;
727 mtx_lock(&ncneg_hot.nl_lock);
728 if (!(ncp->nc_flag & NCF_HOTNEGATIVE)) {
729 list_locked = true;
730 mtx_lock(&neglist->nl_lock);
731 }
732 } else {
733 list_locked = true;
734 mtx_lock(&neglist->nl_lock);
735 }
736 }
737 if (ncp->nc_flag & NCF_HOTNEGATIVE) {
738 mtx_assert(&ncneg_hot.nl_lock, MA_OWNED);
739 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst);
740 } else {
741 mtx_assert(&neglist->nl_lock, MA_OWNED);
742 TAILQ_REMOVE(&neglist->nl_list, ncp, nc_dst);
743 }
744 if (list_locked)
745 mtx_unlock(&neglist->nl_lock);
746 if (hot_locked)
747 mtx_unlock(&ncneg_hot.nl_lock);
748 atomic_subtract_rel_long(&numneg, 1);
749 }
750
751 static void
752 cache_negative_shrink_select(int start, struct namecache **ncpp,
753 struct neglist **neglistpp)
754 {
755 struct neglist *neglist;
756 struct namecache *ncp;
757 int i;
758
759 *ncpp = ncp = NULL;
760 neglist = NULL;
761
762 for (i = start; i < numneglists; i++) {
763 neglist = &neglists[i];
764 if (TAILQ_FIRST(&neglist->nl_list) == NULL)
765 continue;
766 mtx_lock(&neglist->nl_lock);
767 ncp = TAILQ_FIRST(&neglist->nl_list);
768 if (ncp != NULL)
769 break;
770 mtx_unlock(&neglist->nl_lock);
771 }
772
773 *neglistpp = neglist;
774 *ncpp = ncp;
775 }
776
777 static void
778 cache_negative_zap_one(void)
779 {
780 struct namecache *ncp, *ncp2;
781 struct neglist *neglist;
782 struct mtx *dvlp;
783 struct rwlock *blp;
784
785 if (!mtx_trylock(&ncneg_shrink_lock))
786 return;
787
788 mtx_lock(&ncneg_hot.nl_lock);
789 ncp = TAILQ_FIRST(&ncneg_hot.nl_list);
790 if (ncp != NULL) {
791 neglist = NCP2NEGLIST(ncp);
792 mtx_lock(&neglist->nl_lock);
793 TAILQ_REMOVE(&ncneg_hot.nl_list, ncp, nc_dst);
794 TAILQ_INSERT_TAIL(&neglist->nl_list, ncp, nc_dst);
795 ncp->nc_flag &= ~NCF_HOTNEGATIVE;
796 mtx_unlock(&neglist->nl_lock);
797 }
798
799 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist);
800 shrink_list_turn++;
801 if (shrink_list_turn == numneglists)
802 shrink_list_turn = 0;
803 if (ncp == NULL && shrink_list_turn == 0)
804 cache_negative_shrink_select(shrink_list_turn, &ncp, &neglist);
805 if (ncp == NULL) {
806 mtx_unlock(&ncneg_hot.nl_lock);
807 goto out;
808 }
809
810 MPASS(ncp->nc_flag & NCF_NEGATIVE);
811 dvlp = VP2VNODELOCK(ncp->nc_dvp);
812 blp = NCP2BUCKETLOCK(ncp);
813 mtx_unlock(&neglist->nl_lock);
814 mtx_unlock(&ncneg_hot.nl_lock);
815 mtx_lock(dvlp);
816 rw_wlock(blp);
817 mtx_lock(&neglist->nl_lock);
818 ncp2 = TAILQ_FIRST(&neglist->nl_list);
819 if (ncp != ncp2 || dvlp != VP2VNODELOCK(ncp2->nc_dvp) ||
820 blp != NCP2BUCKETLOCK(ncp2) || !(ncp2->nc_flag & NCF_NEGATIVE)) {
821 ncp = NULL;
822 goto out_unlock_all;
823 }
824 SDT_PROBE3(vfs, namecache, shrink_negative, done, ncp->nc_dvp,
825 ncp->nc_name, ncp->nc_neghits);
826
827 cache_zap_locked(ncp, true);
828 out_unlock_all:
829 mtx_unlock(&neglist->nl_lock);
830 rw_wunlock(blp);
831 mtx_unlock(dvlp);
832 out:
833 mtx_unlock(&ncneg_shrink_lock);
834 cache_free(ncp);
835 }
836
837 /*
838 * cache_zap_locked():
839 *
840 * Removes a namecache entry from cache, whether it contains an actual
841 * pointer to a vnode or if it is just a negative cache entry.
842 */
843 static void
844 cache_zap_locked(struct namecache *ncp, bool neg_locked)
845 {
846
847 if (!(ncp->nc_flag & NCF_NEGATIVE))
848 cache_assert_vnode_locked(ncp->nc_vp);
849 cache_assert_vnode_locked(ncp->nc_dvp);
850 cache_assert_bucket_locked(ncp, RA_WLOCKED);
851
852 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp,
853 (ncp->nc_flag & NCF_NEGATIVE) ? NULL : ncp->nc_vp);
854 if (!(ncp->nc_flag & NCF_NEGATIVE)) {
855 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp,
856 ncp->nc_name, ncp->nc_vp);
857 } else {
858 SDT_PROBE3(vfs, namecache, zap_negative, done, ncp->nc_dvp,
859 ncp->nc_name, ncp->nc_neghits);
860 }
861 LIST_REMOVE(ncp, nc_hash);
862 if (!(ncp->nc_flag & NCF_NEGATIVE)) {
863 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst);
864 if (ncp == ncp->nc_vp->v_cache_dd)
865 ncp->nc_vp->v_cache_dd = NULL;
866 } else {
867 cache_negative_remove(ncp, neg_locked);
868 }
869 if (ncp->nc_flag & NCF_ISDOTDOT) {
870 if (ncp == ncp->nc_dvp->v_cache_dd)
871 ncp->nc_dvp->v_cache_dd = NULL;
872 } else {
873 LIST_REMOVE(ncp, nc_src);
874 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) {
875 ncp->nc_flag |= NCF_DVDROP;
876 atomic_subtract_rel_long(&numcachehv, 1);
877 }
878 }
879 atomic_subtract_rel_long(&numcache, 1);
880 }
881
882 static void
883 cache_zap_negative_locked_vnode_kl(struct namecache *ncp, struct vnode *vp)
884 {
885 struct rwlock *blp;
886
887 MPASS(ncp->nc_dvp == vp);
888 MPASS(ncp->nc_flag & NCF_NEGATIVE);
889 cache_assert_vnode_locked(vp);
890
891 blp = NCP2BUCKETLOCK(ncp);
892 rw_wlock(blp);
893 cache_zap_locked(ncp, false);
894 rw_wunlock(blp);
895 }
896
897 static bool
898 cache_zap_locked_vnode_kl2(struct namecache *ncp, struct vnode *vp,
899 struct mtx **vlpp)
900 {
901 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock;
902 struct rwlock *blp;
903
904 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp);
905 cache_assert_vnode_locked(vp);
906
907 if (ncp->nc_flag & NCF_NEGATIVE) {
908 if (*vlpp != NULL) {
909 mtx_unlock(*vlpp);
910 *vlpp = NULL;
911 }
912 cache_zap_negative_locked_vnode_kl(ncp, vp);
913 return (true);
914 }
915
916 pvlp = VP2VNODELOCK(vp);
917 blp = NCP2BUCKETLOCK(ncp);
918 vlp1 = VP2VNODELOCK(ncp->nc_dvp);
919 vlp2 = VP2VNODELOCK(ncp->nc_vp);
920
921 if (*vlpp == vlp1 || *vlpp == vlp2) {
922 to_unlock = *vlpp;
923 *vlpp = NULL;
924 } else {
925 if (*vlpp != NULL) {
926 mtx_unlock(*vlpp);
927 *vlpp = NULL;
928 }
929 cache_sort(&vlp1, &vlp2);
930 if (vlp1 == pvlp) {
931 mtx_lock(vlp2);
932 to_unlock = vlp2;
933 } else {
934 if (!mtx_trylock(vlp1))
935 goto out_relock;
936 to_unlock = vlp1;
937 }
938 }
939 rw_wlock(blp);
940 cache_zap_locked(ncp, false);
941 rw_wunlock(blp);
942 if (to_unlock != NULL)
943 mtx_unlock(to_unlock);
944 return (true);
945
946 out_relock:
947 mtx_unlock(vlp2);
948 mtx_lock(vlp1);
949 mtx_lock(vlp2);
950 MPASS(*vlpp == NULL);
951 *vlpp = vlp1;
952 return (false);
953 }
954
955 static int
956 cache_zap_locked_vnode(struct namecache *ncp, struct vnode *vp)
957 {
958 struct mtx *pvlp, *vlp1, *vlp2, *to_unlock;
959 struct rwlock *blp;
960 int error = 0;
961
962 MPASS(vp == ncp->nc_dvp || vp == ncp->nc_vp);
963 cache_assert_vnode_locked(vp);
964
965 pvlp = VP2VNODELOCK(vp);
966 if (ncp->nc_flag & NCF_NEGATIVE) {
967 cache_zap_negative_locked_vnode_kl(ncp, vp);
968 goto out;
969 }
970
971 blp = NCP2BUCKETLOCK(ncp);
972 vlp1 = VP2VNODELOCK(ncp->nc_dvp);
973 vlp2 = VP2VNODELOCK(ncp->nc_vp);
974 cache_sort(&vlp1, &vlp2);
975 if (vlp1 == pvlp) {
976 mtx_lock(vlp2);
977 to_unlock = vlp2;
978 } else {
979 if (!mtx_trylock(vlp1)) {
980 error = EAGAIN;
981 goto out;
982 }
983 to_unlock = vlp1;
984 }
985 rw_wlock(blp);
986 cache_zap_locked(ncp, false);
987 rw_wunlock(blp);
988 mtx_unlock(to_unlock);
989 out:
990 mtx_unlock(pvlp);
991 return (error);
992 }
993
994 static int
995 cache_zap_wlocked_bucket(struct namecache *ncp, struct rwlock *blp)
996 {
997 struct mtx *dvlp, *vlp;
998
999 cache_assert_bucket_locked(ncp, RA_WLOCKED);
1000
1001 dvlp = VP2VNODELOCK(ncp->nc_dvp);
1002 vlp = NULL;
1003 if (!(ncp->nc_flag & NCF_NEGATIVE))
1004 vlp = VP2VNODELOCK(ncp->nc_vp);
1005 if (cache_trylock_vnodes(dvlp, vlp) == 0) {
1006 cache_zap_locked(ncp, false);
1007 rw_wunlock(blp);
1008 cache_unlock_vnodes(dvlp, vlp);
1009 return (0);
1010 }
1011
1012 rw_wunlock(blp);
1013 return (EAGAIN);
1014 }
1015
1016 static int
1017 cache_zap_rlocked_bucket(struct namecache *ncp, struct rwlock *blp)
1018 {
1019 struct mtx *dvlp, *vlp;
1020
1021 cache_assert_bucket_locked(ncp, RA_RLOCKED);
1022
1023 dvlp = VP2VNODELOCK(ncp->nc_dvp);
1024 vlp = NULL;
1025 if (!(ncp->nc_flag & NCF_NEGATIVE))
1026 vlp = VP2VNODELOCK(ncp->nc_vp);
1027 if (cache_trylock_vnodes(dvlp, vlp) == 0) {
1028 rw_runlock(blp);
1029 rw_wlock(blp);
1030 cache_zap_locked(ncp, false);
1031 rw_wunlock(blp);
1032 cache_unlock_vnodes(dvlp, vlp);
1033 return (0);
1034 }
1035
1036 rw_runlock(blp);
1037 return (EAGAIN);
1038 }
1039
1040 static int
1041 cache_zap_wlocked_bucket_kl(struct namecache *ncp, struct rwlock *blp,
1042 struct mtx **vlpp1, struct mtx **vlpp2)
1043 {
1044 struct mtx *dvlp, *vlp;
1045
1046 cache_assert_bucket_locked(ncp, RA_WLOCKED);
1047
1048 dvlp = VP2VNODELOCK(ncp->nc_dvp);
1049 vlp = NULL;
1050 if (!(ncp->nc_flag & NCF_NEGATIVE))
1051 vlp = VP2VNODELOCK(ncp->nc_vp);
1052 cache_sort(&dvlp, &vlp);
1053
1054 if (*vlpp1 == dvlp && *vlpp2 == vlp) {
1055 cache_zap_locked(ncp, false);
1056 cache_unlock_vnodes(dvlp, vlp);
1057 *vlpp1 = NULL;
1058 *vlpp2 = NULL;
1059 return (0);
1060 }
1061
1062 if (*vlpp1 != NULL)
1063 mtx_unlock(*vlpp1);
1064 if (*vlpp2 != NULL)
1065 mtx_unlock(*vlpp2);
1066 *vlpp1 = NULL;
1067 *vlpp2 = NULL;
1068
1069 if (cache_trylock_vnodes(dvlp, vlp) == 0) {
1070 cache_zap_locked(ncp, false);
1071 cache_unlock_vnodes(dvlp, vlp);
1072 return (0);
1073 }
1074
1075 rw_wunlock(blp);
1076 *vlpp1 = dvlp;
1077 *vlpp2 = vlp;
1078 if (*vlpp1 != NULL)
1079 mtx_lock(*vlpp1);
1080 mtx_lock(*vlpp2);
1081 rw_wlock(blp);
1082 return (EAGAIN);
1083 }
1084
1085 static void
1086 cache_lookup_unlock(struct rwlock *blp, struct mtx *vlp)
1087 {
1088
1089 if (blp != NULL) {
1090 rw_runlock(blp);
1091 } else {
1092 mtx_unlock(vlp);
1093 }
1094 }
1095
1096 static int __noinline
1097 cache_lookup_dot(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
1098 struct timespec *tsp, int *ticksp)
1099 {
1100 int ltype;
1101
1102 *vpp = dvp;
1103 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .",
1104 dvp, cnp->cn_nameptr);
1105 counter_u64_add(dothits, 1);
1106 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp);
1107 if (tsp != NULL)
1108 timespecclear(tsp);
1109 if (ticksp != NULL)
1110 *ticksp = ticks;
1111 vrefact(*vpp);
1112 /*
1113 * When we lookup "." we still can be asked to lock it
1114 * differently...
1115 */
1116 ltype = cnp->cn_lkflags & LK_TYPE_MASK;
1117 if (ltype != VOP_ISLOCKED(*vpp)) {
1118 if (ltype == LK_EXCLUSIVE) {
1119 vn_lock(*vpp, LK_UPGRADE | LK_RETRY);
1120 if ((*vpp)->v_iflag & VI_DOOMED) {
1121 /* forced unmount */
1122 vrele(*vpp);
1123 *vpp = NULL;
1124 return (ENOENT);
1125 }
1126 } else
1127 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY);
1128 }
1129 return (-1);
1130 }
1131
1132 /*
1133 * Lookup an entry in the cache
1134 *
1135 * Lookup is called with dvp pointing to the directory to search,
1136 * cnp pointing to the name of the entry being sought. If the lookup
1137 * succeeds, the vnode is returned in *vpp, and a status of -1 is
1138 * returned. If the lookup determines that the name does not exist
1139 * (negative caching), a status of ENOENT is returned. If the lookup
1140 * fails, a status of zero is returned. If the directory vnode is
1141 * recycled out from under us due to a forced unmount, a status of
1142 * ENOENT is returned.
1143 *
1144 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is
1145 * unlocked. If we're looking up . an extra ref is taken, but the lock is
1146 * not recursively acquired.
1147 */
1148
1149 static __noinline int
1150 cache_lookup_nomakeentry(struct vnode *dvp, struct vnode **vpp,
1151 struct componentname *cnp, struct timespec *tsp, int *ticksp)
1152 {
1153 struct namecache *ncp;
1154 struct rwlock *blp;
1155 struct mtx *dvlp, *dvlp2;
1156 uint32_t hash;
1157 int error;
1158
1159 if (cnp->cn_namelen == 2 &&
1160 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') {
1161 counter_u64_add(dotdothits, 1);
1162 dvlp = VP2VNODELOCK(dvp);
1163 dvlp2 = NULL;
1164 mtx_lock(dvlp);
1165 retry_dotdot:
1166 ncp = dvp->v_cache_dd;
1167 if (ncp == NULL) {
1168 SDT_PROBE3(vfs, namecache, lookup, miss, dvp,
1169 "..", NULL);
1170 mtx_unlock(dvlp);
1171 if (dvlp2 != NULL)
1172 mtx_unlock(dvlp2);
1173 return (0);
1174 }
1175 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) {
1176 if (ncp->nc_dvp != dvp)
1177 panic("dvp %p v_cache_dd %p\n", dvp, ncp);
1178 if (!cache_zap_locked_vnode_kl2(ncp,
1179 dvp, &dvlp2))
1180 goto retry_dotdot;
1181 MPASS(dvp->v_cache_dd == NULL);
1182 mtx_unlock(dvlp);
1183 if (dvlp2 != NULL)
1184 mtx_unlock(dvlp2);
1185 cache_free(ncp);
1186 } else {
1187 dvp->v_cache_dd = NULL;
1188 mtx_unlock(dvlp);
1189 if (dvlp2 != NULL)
1190 mtx_unlock(dvlp2);
1191 }
1192 return (0);
1193 }
1194
1195 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
1196 blp = HASH2BUCKETLOCK(hash);
1197 retry:
1198 if (LIST_EMPTY(NCHHASH(hash)))
1199 goto out_no_entry;
1200
1201 rw_wlock(blp);
1202
1203 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
1204 counter_u64_add(numchecks, 1);
1205 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
1206 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))
1207 break;
1208 }
1209
1210 /* We failed to find an entry */
1211 if (ncp == NULL) {
1212 rw_wunlock(blp);
1213 goto out_no_entry;
1214 }
1215
1216 counter_u64_add(numposzaps, 1);
1217
1218 error = cache_zap_wlocked_bucket(ncp, blp);
1219 if (error != 0) {
1220 zap_and_exit_bucket_fail++;
1221 cache_maybe_yield();
1222 goto retry;
1223 }
1224 cache_free(ncp);
1225 return (0);
1226 out_no_entry:
1227 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, NULL);
1228 counter_u64_add(nummisszap, 1);
1229 return (0);
1230 }
1231
1232 int
1233 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
1234 struct timespec *tsp, int *ticksp)
1235 {
1236 struct namecache_ts *ncp_ts;
1237 struct namecache *ncp;
1238 struct rwlock *blp;
1239 struct mtx *dvlp;
1240 uint32_t hash;
1241 int error, ltype;
1242
1243 if (__predict_false(!doingcache)) {
1244 cnp->cn_flags &= ~MAKEENTRY;
1245 return (0);
1246 }
1247
1248 counter_u64_add(numcalls, 1);
1249
1250 if (__predict_false(cnp->cn_namelen == 1 && cnp->cn_nameptr[0] == '.'))
1251 return (cache_lookup_dot(dvp, vpp, cnp, tsp, ticksp));
1252
1253 if ((cnp->cn_flags & MAKEENTRY) == 0)
1254 return (cache_lookup_nomakeentry(dvp, vpp, cnp, tsp, ticksp));
1255
1256 retry:
1257 blp = NULL;
1258 dvlp = NULL;
1259 error = 0;
1260 if (cnp->cn_namelen == 2 &&
1261 cnp->cn_nameptr[0] == '.' && cnp->cn_nameptr[1] == '.') {
1262 counter_u64_add(dotdothits, 1);
1263 dvlp = VP2VNODELOCK(dvp);
1264 mtx_lock(dvlp);
1265 ncp = dvp->v_cache_dd;
1266 if (ncp == NULL) {
1267 SDT_PROBE3(vfs, namecache, lookup, miss, dvp,
1268 "..", NULL);
1269 mtx_unlock(dvlp);
1270 return (0);
1271 }
1272 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) {
1273 if (ncp->nc_flag & NCF_NEGATIVE)
1274 *vpp = NULL;
1275 else
1276 *vpp = ncp->nc_vp;
1277 } else
1278 *vpp = ncp->nc_dvp;
1279 /* Return failure if negative entry was found. */
1280 if (*vpp == NULL)
1281 goto negative_success;
1282 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..",
1283 dvp, cnp->cn_nameptr, *vpp);
1284 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..",
1285 *vpp);
1286 cache_out_ts(ncp, tsp, ticksp);
1287 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) ==
1288 NCF_DTS && tsp != NULL) {
1289 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc);
1290 *tsp = ncp_ts->nc_dotdottime;
1291 }
1292 goto success;
1293 }
1294
1295 hash = cache_get_hash(cnp->cn_nameptr, cnp->cn_namelen, dvp);
1296 blp = HASH2BUCKETLOCK(hash);
1297 rw_rlock(blp);
1298
1299 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
1300 counter_u64_add(numchecks, 1);
1301 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
1302 !bcmp(ncp->nc_name, cnp->cn_nameptr, ncp->nc_nlen))
1303 break;
1304 }
1305
1306 /* We failed to find an entry */
1307 if (ncp == NULL) {
1308 rw_runlock(blp);
1309 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr,
1310 NULL);
1311 counter_u64_add(nummiss, 1);
1312 return (0);
1313 }
1314
1315 /* We found a "positive" match, return the vnode */
1316 if (!(ncp->nc_flag & NCF_NEGATIVE)) {
1317 counter_u64_add(numposhits, 1);
1318 *vpp = ncp->nc_vp;
1319 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p",
1320 dvp, cnp->cn_nameptr, *vpp, ncp);
1321 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ncp->nc_name,
1322 *vpp);
1323 cache_out_ts(ncp, tsp, ticksp);
1324 goto success;
1325 }
1326
1327 negative_success:
1328 /* We found a negative match, and want to create it, so purge */
1329 if (cnp->cn_nameiop == CREATE) {
1330 counter_u64_add(numnegzaps, 1);
1331 goto zap_and_exit;
1332 }
1333
1334 counter_u64_add(numneghits, 1);
1335 cache_negative_hit(ncp);
1336 if (ncp->nc_flag & NCF_WHITE)
1337 cnp->cn_flags |= ISWHITEOUT;
1338 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp,
1339 ncp->nc_name);
1340 cache_out_ts(ncp, tsp, ticksp);
1341 cache_lookup_unlock(blp, dvlp);
1342 return (ENOENT);
1343
1344 success:
1345 /*
1346 * On success we return a locked and ref'd vnode as per the lookup
1347 * protocol.
1348 */
1349 MPASS(dvp != *vpp);
1350 ltype = 0; /* silence gcc warning */
1351 if (cnp->cn_flags & ISDOTDOT) {
1352 ltype = VOP_ISLOCKED(dvp);
1353 VOP_UNLOCK(dvp, 0);
1354 }
1355 vhold(*vpp);
1356 cache_lookup_unlock(blp, dvlp);
1357 error = vget(*vpp, cnp->cn_lkflags | LK_VNHELD, cnp->cn_thread);
1358 if (cnp->cn_flags & ISDOTDOT) {
1359 vn_lock(dvp, ltype | LK_RETRY);
1360 if (dvp->v_iflag & VI_DOOMED) {
1361 if (error == 0)
1362 vput(*vpp);
1363 *vpp = NULL;
1364 return (ENOENT);
1365 }
1366 }
1367 if (error) {
1368 *vpp = NULL;
1369 goto retry;
1370 }
1371 if ((cnp->cn_flags & ISLASTCN) &&
1372 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) {
1373 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup");
1374 }
1375 return (-1);
1376
1377 zap_and_exit:
1378 if (blp != NULL)
1379 error = cache_zap_rlocked_bucket(ncp, blp);
1380 else
1381 error = cache_zap_locked_vnode(ncp, dvp);
1382 if (error != 0) {
1383 zap_and_exit_bucket_fail++;
1384 cache_maybe_yield();
1385 goto retry;
1386 }
1387 cache_free(ncp);
1388 return (0);
1389 }
1390
1391 struct celockstate {
1392 struct mtx *vlp[3];
1393 struct rwlock *blp[2];
1394 };
1395 CTASSERT((nitems(((struct celockstate *)0)->vlp) == 3));
1396 CTASSERT((nitems(((struct celockstate *)0)->blp) == 2));
1397
1398 static inline void
1399 cache_celockstate_init(struct celockstate *cel)
1400 {
1401
1402 bzero(cel, sizeof(*cel));
1403 }
1404
1405 static void
1406 cache_lock_vnodes_cel(struct celockstate *cel, struct vnode *vp,
1407 struct vnode *dvp)
1408 {
1409 struct mtx *vlp1, *vlp2;
1410
1411 MPASS(cel->vlp[0] == NULL);
1412 MPASS(cel->vlp[1] == NULL);
1413 MPASS(cel->vlp[2] == NULL);
1414
1415 MPASS(vp != NULL || dvp != NULL);
1416
1417 vlp1 = VP2VNODELOCK(vp);
1418 vlp2 = VP2VNODELOCK(dvp);
1419 cache_sort(&vlp1, &vlp2);
1420
1421 if (vlp1 != NULL) {
1422 mtx_lock(vlp1);
1423 cel->vlp[0] = vlp1;
1424 }
1425 mtx_lock(vlp2);
1426 cel->vlp[1] = vlp2;
1427 }
1428
1429 static void
1430 cache_unlock_vnodes_cel(struct celockstate *cel)
1431 {
1432
1433 MPASS(cel->vlp[0] != NULL || cel->vlp[1] != NULL);
1434
1435 if (cel->vlp[0] != NULL)
1436 mtx_unlock(cel->vlp[0]);
1437 if (cel->vlp[1] != NULL)
1438 mtx_unlock(cel->vlp[1]);
1439 if (cel->vlp[2] != NULL)
1440 mtx_unlock(cel->vlp[2]);
1441 }
1442
1443 static bool
1444 cache_lock_vnodes_cel_3(struct celockstate *cel, struct vnode *vp)
1445 {
1446 struct mtx *vlp;
1447 bool ret;
1448
1449 cache_assert_vlp_locked(cel->vlp[0]);
1450 cache_assert_vlp_locked(cel->vlp[1]);
1451 MPASS(cel->vlp[2] == NULL);
1452
1453 MPASS(vp != NULL);
1454 vlp = VP2VNODELOCK(vp);
1455
1456 ret = true;
1457 if (vlp >= cel->vlp[1]) {
1458 mtx_lock(vlp);
1459 } else {
1460 if (mtx_trylock(vlp))
1461 goto out;
1462 cache_lock_vnodes_cel_3_failures++;
1463 cache_unlock_vnodes_cel(cel);
1464 if (vlp < cel->vlp[0]) {
1465 mtx_lock(vlp);
1466 mtx_lock(cel->vlp[0]);
1467 mtx_lock(cel->vlp[1]);
1468 } else {
1469 if (cel->vlp[0] != NULL)
1470 mtx_lock(cel->vlp[0]);
1471 mtx_lock(vlp);
1472 mtx_lock(cel->vlp[1]);
1473 }
1474 ret = false;
1475 }
1476 out:
1477 cel->vlp[2] = vlp;
1478 return (ret);
1479 }
1480
1481 static void
1482 cache_lock_buckets_cel(struct celockstate *cel, struct rwlock *blp1,
1483 struct rwlock *blp2)
1484 {
1485
1486 MPASS(cel->blp[0] == NULL);
1487 MPASS(cel->blp[1] == NULL);
1488
1489 cache_sort(&blp1, &blp2);
1490
1491 if (blp1 != NULL) {
1492 rw_wlock(blp1);
1493 cel->blp[0] = blp1;
1494 }
1495 rw_wlock(blp2);
1496 cel->blp[1] = blp2;
1497 }
1498
1499 static void
1500 cache_unlock_buckets_cel(struct celockstate *cel)
1501 {
1502
1503 if (cel->blp[0] != NULL)
1504 rw_wunlock(cel->blp[0]);
1505 rw_wunlock(cel->blp[1]);
1506 }
1507
1508 /*
1509 * Lock part of the cache affected by the insertion.
1510 *
1511 * This means vnodelocks for dvp, vp and the relevant bucketlock.
1512 * However, insertion can result in removal of an old entry. In this
1513 * case we have an additional vnode and bucketlock pair to lock. If the
1514 * entry is negative, ncelock is locked instead of the vnode.
1515 *
1516 * That is, in the worst case we have to lock 3 vnodes and 2 bucketlocks, while
1517 * preserving the locking order (smaller address first).
1518 */
1519 static void
1520 cache_enter_lock(struct celockstate *cel, struct vnode *dvp, struct vnode *vp,
1521 uint32_t hash)
1522 {
1523 struct namecache *ncp;
1524 struct rwlock *blps[2];
1525
1526 blps[0] = HASH2BUCKETLOCK(hash);
1527 for (;;) {
1528 blps[1] = NULL;
1529 cache_lock_vnodes_cel(cel, dvp, vp);
1530 if (vp == NULL || vp->v_type != VDIR)
1531 break;
1532 ncp = vp->v_cache_dd;
1533 if (ncp == NULL)
1534 break;
1535 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
1536 break;
1537 MPASS(ncp->nc_dvp == vp);
1538 blps[1] = NCP2BUCKETLOCK(ncp);
1539 if (ncp->nc_flag & NCF_NEGATIVE)
1540 break;
1541 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp))
1542 break;
1543 /*
1544 * All vnodes got re-locked. Re-validate the state and if
1545 * nothing changed we are done. Otherwise restart.
1546 */
1547 if (ncp == vp->v_cache_dd &&
1548 (ncp->nc_flag & NCF_ISDOTDOT) != 0 &&
1549 blps[1] == NCP2BUCKETLOCK(ncp) &&
1550 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2])
1551 break;
1552 cache_unlock_vnodes_cel(cel);
1553 cel->vlp[0] = NULL;
1554 cel->vlp[1] = NULL;
1555 cel->vlp[2] = NULL;
1556 }
1557 cache_lock_buckets_cel(cel, blps[0], blps[1]);
1558 }
1559
1560 static void
1561 cache_enter_lock_dd(struct celockstate *cel, struct vnode *dvp, struct vnode *vp,
1562 uint32_t hash)
1563 {
1564 struct namecache *ncp;
1565 struct rwlock *blps[2];
1566
1567 blps[0] = HASH2BUCKETLOCK(hash);
1568 for (;;) {
1569 blps[1] = NULL;
1570 cache_lock_vnodes_cel(cel, dvp, vp);
1571 ncp = dvp->v_cache_dd;
1572 if (ncp == NULL)
1573 break;
1574 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
1575 break;
1576 MPASS(ncp->nc_dvp == dvp);
1577 blps[1] = NCP2BUCKETLOCK(ncp);
1578 if (ncp->nc_flag & NCF_NEGATIVE)
1579 break;
1580 if (cache_lock_vnodes_cel_3(cel, ncp->nc_vp))
1581 break;
1582 if (ncp == dvp->v_cache_dd &&
1583 (ncp->nc_flag & NCF_ISDOTDOT) != 0 &&
1584 blps[1] == NCP2BUCKETLOCK(ncp) &&
1585 VP2VNODELOCK(ncp->nc_vp) == cel->vlp[2])
1586 break;
1587 cache_unlock_vnodes_cel(cel);
1588 cel->vlp[0] = NULL;
1589 cel->vlp[1] = NULL;
1590 cel->vlp[2] = NULL;
1591 }
1592 cache_lock_buckets_cel(cel, blps[0], blps[1]);
1593 }
1594
1595 static void
1596 cache_enter_unlock(struct celockstate *cel)
1597 {
1598
1599 cache_unlock_buckets_cel(cel);
1600 cache_unlock_vnodes_cel(cel);
1601 }
1602
1603 /*
1604 * Add an entry to the cache.
1605 */
1606 void
1607 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp,
1608 struct timespec *tsp, struct timespec *dtsp)
1609 {
1610 struct celockstate cel;
1611 struct namecache *ncp, *n2, *ndd;
1612 struct namecache_ts *ncp_ts, *n2_ts;
1613 struct nchashhead *ncpp;
1614 struct neglist *neglist;
1615 uint32_t hash;
1616 int flag;
1617 int len;
1618 bool neg_locked;
1619 int lnumcache;
1620
1621 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr);
1622 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp,
1623 ("cache_enter: Adding a doomed vnode"));
1624 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp,
1625 ("cache_enter: Doomed vnode used as src"));
1626
1627 if (__predict_false(!doingcache))
1628 return;
1629
1630 /*
1631 * Avoid blowout in namecache entries.
1632 */
1633 if (__predict_false(numcache >= desiredvnodes * ncsizefactor))
1634 return;
1635
1636 cache_celockstate_init(&cel);
1637 ndd = NULL;
1638 ncp_ts = NULL;
1639 flag = 0;
1640 if (cnp->cn_nameptr[0] == '.') {
1641 if (cnp->cn_namelen == 1)
1642 return;
1643 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
1644 len = cnp->cn_namelen;
1645 hash = cache_get_hash(cnp->cn_nameptr, len, dvp);
1646 cache_enter_lock_dd(&cel, dvp, vp, hash);
1647 /*
1648 * If dotdot entry already exists, just retarget it
1649 * to new parent vnode, otherwise continue with new
1650 * namecache entry allocation.
1651 */
1652 if ((ncp = dvp->v_cache_dd) != NULL &&
1653 ncp->nc_flag & NCF_ISDOTDOT) {
1654 KASSERT(ncp->nc_dvp == dvp,
1655 ("wrong isdotdot parent"));
1656 neg_locked = false;
1657 if (ncp->nc_flag & NCF_NEGATIVE || vp == NULL) {
1658 neglist = NCP2NEGLIST(ncp);
1659 mtx_lock(&ncneg_hot.nl_lock);
1660 mtx_lock(&neglist->nl_lock);
1661 neg_locked = true;
1662 }
1663 if (!(ncp->nc_flag & NCF_NEGATIVE)) {
1664 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst,
1665 ncp, nc_dst);
1666 } else {
1667 cache_negative_remove(ncp, true);
1668 }
1669 if (vp != NULL) {
1670 TAILQ_INSERT_HEAD(&vp->v_cache_dst,
1671 ncp, nc_dst);
1672 ncp->nc_flag &= ~(NCF_NEGATIVE|NCF_HOTNEGATIVE);
1673 } else {
1674 ncp->nc_flag &= ~(NCF_HOTNEGATIVE);
1675 ncp->nc_flag |= NCF_NEGATIVE;
1676 cache_negative_insert(ncp, true);
1677 }
1678 if (neg_locked) {
1679 mtx_unlock(&neglist->nl_lock);
1680 mtx_unlock(&ncneg_hot.nl_lock);
1681 }
1682 ncp->nc_vp = vp;
1683 cache_enter_unlock(&cel);
1684 return;
1685 }
1686 dvp->v_cache_dd = NULL;
1687 cache_enter_unlock(&cel);
1688 cache_celockstate_init(&cel);
1689 SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp);
1690 flag = NCF_ISDOTDOT;
1691 }
1692 }
1693
1694 /*
1695 * Calculate the hash key and setup as much of the new
1696 * namecache entry as possible before acquiring the lock.
1697 */
1698 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL);
1699 ncp->nc_flag = flag;
1700 ncp->nc_vp = vp;
1701 if (vp == NULL)
1702 ncp->nc_flag |= NCF_NEGATIVE;
1703 ncp->nc_dvp = dvp;
1704 if (tsp != NULL) {
1705 ncp_ts = __containerof(ncp, struct namecache_ts, nc_nc);
1706 ncp_ts->nc_time = *tsp;
1707 ncp_ts->nc_ticks = ticks;
1708 ncp_ts->nc_nc.nc_flag |= NCF_TS;
1709 if (dtsp != NULL) {
1710 ncp_ts->nc_dotdottime = *dtsp;
1711 ncp_ts->nc_nc.nc_flag |= NCF_DTS;
1712 }
1713 }
1714 len = ncp->nc_nlen = cnp->cn_namelen;
1715 hash = cache_get_hash(cnp->cn_nameptr, len, dvp);
1716 strlcpy(ncp->nc_name, cnp->cn_nameptr, len + 1);
1717 cache_enter_lock(&cel, dvp, vp, hash);
1718
1719 /*
1720 * See if this vnode or negative entry is already in the cache
1721 * with this name. This can happen with concurrent lookups of
1722 * the same path name.
1723 */
1724 ncpp = NCHHASH(hash);
1725 LIST_FOREACH(n2, ncpp, nc_hash) {
1726 if (n2->nc_dvp == dvp &&
1727 n2->nc_nlen == cnp->cn_namelen &&
1728 !bcmp(n2->nc_name, cnp->cn_nameptr, n2->nc_nlen)) {
1729 if (tsp != NULL) {
1730 KASSERT((n2->nc_flag & NCF_TS) != 0,
1731 ("no NCF_TS"));
1732 n2_ts = __containerof(n2, struct namecache_ts, nc_nc);
1733 n2_ts->nc_time = ncp_ts->nc_time;
1734 n2_ts->nc_ticks = ncp_ts->nc_ticks;
1735 if (dtsp != NULL) {
1736 n2_ts->nc_dotdottime = ncp_ts->nc_dotdottime;
1737 if (ncp->nc_flag & NCF_NEGATIVE)
1738 mtx_lock(&ncneg_hot.nl_lock);
1739 n2_ts->nc_nc.nc_flag |= NCF_DTS;
1740 if (ncp->nc_flag & NCF_NEGATIVE)
1741 mtx_unlock(&ncneg_hot.nl_lock);
1742 }
1743 }
1744 goto out_unlock_free;
1745 }
1746 }
1747
1748 if (flag == NCF_ISDOTDOT) {
1749 /*
1750 * See if we are trying to add .. entry, but some other lookup
1751 * has populated v_cache_dd pointer already.
1752 */
1753 if (dvp->v_cache_dd != NULL)
1754 goto out_unlock_free;
1755 KASSERT(vp == NULL || vp->v_type == VDIR,
1756 ("wrong vnode type %p", vp));
1757 dvp->v_cache_dd = ncp;
1758 }
1759
1760 if (vp != NULL) {
1761 if (vp->v_type == VDIR) {
1762 if (flag != NCF_ISDOTDOT) {
1763 /*
1764 * For this case, the cache entry maps both the
1765 * directory name in it and the name ".." for the
1766 * directory's parent.
1767 */
1768 if ((ndd = vp->v_cache_dd) != NULL) {
1769 if ((ndd->nc_flag & NCF_ISDOTDOT) != 0)
1770 cache_zap_locked(ndd, false);
1771 else
1772 ndd = NULL;
1773 }
1774 vp->v_cache_dd = ncp;
1775 }
1776 } else {
1777 vp->v_cache_dd = NULL;
1778 }
1779 }
1780
1781 if (flag != NCF_ISDOTDOT) {
1782 if (LIST_EMPTY(&dvp->v_cache_src)) {
1783 vhold(dvp);
1784 atomic_add_rel_long(&numcachehv, 1);
1785 }
1786 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src);
1787 }
1788
1789 /*
1790 * Insert the new namecache entry into the appropriate chain
1791 * within the cache entries table.
1792 */
1793 LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
1794
1795 /*
1796 * If the entry is "negative", we place it into the
1797 * "negative" cache queue, otherwise, we place it into the
1798 * destination vnode's cache entries queue.
1799 */
1800 if (vp != NULL) {
1801 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst);
1802 SDT_PROBE3(vfs, namecache, enter, done, dvp, ncp->nc_name,
1803 vp);
1804 } else {
1805 if (cnp->cn_flags & ISWHITEOUT)
1806 ncp->nc_flag |= NCF_WHITE;
1807 cache_negative_insert(ncp, false);
1808 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp,
1809 ncp->nc_name);
1810 }
1811 cache_enter_unlock(&cel);
1812 lnumcache = atomic_fetchadd_long(&numcache, 1) + 1;
1813 if (numneg * ncnegfactor > lnumcache)
1814 cache_negative_zap_one();
1815 cache_free(ndd);
1816 return;
1817 out_unlock_free:
1818 cache_enter_unlock(&cel);
1819 cache_free(ncp);
1820 return;
1821 }
1822
1823 static u_int
1824 cache_roundup_2(u_int val)
1825 {
1826 u_int res;
1827
1828 for (res = 1; res <= val; res <<= 1)
1829 continue;
1830
1831 return (res);
1832 }
1833
1834 /*
1835 * Name cache initialization, from vfs_init() when we are booting
1836 */
1837 static void
1838 nchinit(void *dummy __unused)
1839 {
1840 u_int i;
1841
1842 cache_zone_small = uma_zcreate("S VFS Cache",
1843 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1,
1844 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache),
1845 UMA_ZONE_ZINIT);
1846 cache_zone_small_ts = uma_zcreate("STS VFS Cache",
1847 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1,
1848 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts),
1849 UMA_ZONE_ZINIT);
1850 cache_zone_large = uma_zcreate("L VFS Cache",
1851 sizeof(struct namecache) + NAME_MAX + 1,
1852 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache),
1853 UMA_ZONE_ZINIT);
1854 cache_zone_large_ts = uma_zcreate("LTS VFS Cache",
1855 sizeof(struct namecache_ts) + NAME_MAX + 1,
1856 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts),
1857 UMA_ZONE_ZINIT);
1858
1859 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash);
1860 ncbuckethash = cache_roundup_2(mp_ncpus * 64) - 1;
1861 if (ncbuckethash > nchash)
1862 ncbuckethash = nchash;
1863 bucketlocks = malloc(sizeof(*bucketlocks) * numbucketlocks, M_VFSCACHE,
1864 M_WAITOK | M_ZERO);
1865 for (i = 0; i < numbucketlocks; i++)
1866 rw_init_flags(&bucketlocks[i], "ncbuc", RW_DUPOK | RW_RECURSE);
1867 ncvnodehash = cache_roundup_2(mp_ncpus * 64) - 1;
1868 vnodelocks = malloc(sizeof(*vnodelocks) * numvnodelocks, M_VFSCACHE,
1869 M_WAITOK | M_ZERO);
1870 for (i = 0; i < numvnodelocks; i++)
1871 mtx_init(&vnodelocks[i], "ncvn", NULL, MTX_DUPOK | MTX_RECURSE);
1872 ncpurgeminvnodes = numbucketlocks;
1873
1874 ncneghash = 3;
1875 neglists = malloc(sizeof(*neglists) * numneglists, M_VFSCACHE,
1876 M_WAITOK | M_ZERO);
1877 for (i = 0; i < numneglists; i++) {
1878 mtx_init(&neglists[i].nl_lock, "ncnegl", NULL, MTX_DEF);
1879 TAILQ_INIT(&neglists[i].nl_list);
1880 }
1881 mtx_init(&ncneg_hot.nl_lock, "ncneglh", NULL, MTX_DEF);
1882 TAILQ_INIT(&ncneg_hot.nl_list);
1883
1884 mtx_init(&ncneg_shrink_lock, "ncnegs", NULL, MTX_DEF);
1885
1886 numcalls = counter_u64_alloc(M_WAITOK);
1887 dothits = counter_u64_alloc(M_WAITOK);
1888 dotdothits = counter_u64_alloc(M_WAITOK);
1889 numchecks = counter_u64_alloc(M_WAITOK);
1890 nummiss = counter_u64_alloc(M_WAITOK);
1891 nummisszap = counter_u64_alloc(M_WAITOK);
1892 numposzaps = counter_u64_alloc(M_WAITOK);
1893 numposhits = counter_u64_alloc(M_WAITOK);
1894 numnegzaps = counter_u64_alloc(M_WAITOK);
1895 numneghits = counter_u64_alloc(M_WAITOK);
1896 numfullpathcalls = counter_u64_alloc(M_WAITOK);
1897 numfullpathfail1 = counter_u64_alloc(M_WAITOK);
1898 numfullpathfail2 = counter_u64_alloc(M_WAITOK);
1899 numfullpathfail4 = counter_u64_alloc(M_WAITOK);
1900 numfullpathfound = counter_u64_alloc(M_WAITOK);
1901 }
1902 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
1903
1904 void
1905 cache_changesize(int newmaxvnodes)
1906 {
1907 struct nchashhead *new_nchashtbl, *old_nchashtbl;
1908 u_long new_nchash, old_nchash;
1909 struct namecache *ncp;
1910 uint32_t hash;
1911 int i;
1912
1913 newmaxvnodes = cache_roundup_2(newmaxvnodes * 2);
1914 if (newmaxvnodes < numbucketlocks)
1915 newmaxvnodes = numbucketlocks;
1916
1917 new_nchashtbl = hashinit(newmaxvnodes, M_VFSCACHE, &new_nchash);
1918 /* If same hash table size, nothing to do */
1919 if (nchash == new_nchash) {
1920 free(new_nchashtbl, M_VFSCACHE);
1921 return;
1922 }
1923 /*
1924 * Move everything from the old hash table to the new table.
1925 * None of the namecache entries in the table can be removed
1926 * because to do so, they have to be removed from the hash table.
1927 */
1928 cache_lock_all_vnodes();
1929 cache_lock_all_buckets();
1930 old_nchashtbl = nchashtbl;
1931 old_nchash = nchash;
1932 nchashtbl = new_nchashtbl;
1933 nchash = new_nchash;
1934 for (i = 0; i <= old_nchash; i++) {
1935 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) {
1936 hash = cache_get_hash(ncp->nc_name, ncp->nc_nlen,
1937 ncp->nc_dvp);
1938 LIST_REMOVE(ncp, nc_hash);
1939 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash);
1940 }
1941 }
1942 cache_unlock_all_buckets();
1943 cache_unlock_all_vnodes();
1944 free(old_nchashtbl, M_VFSCACHE);
1945 }
1946
1947 /*
1948 * Invalidate all entries to a particular vnode.
1949 */
1950 void
1951 cache_purge(struct vnode *vp)
1952 {
1953 TAILQ_HEAD(, namecache) ncps;
1954 struct namecache *ncp, *nnp;
1955 struct mtx *vlp, *vlp2;
1956
1957 CTR1(KTR_VFS, "cache_purge(%p)", vp);
1958 SDT_PROBE1(vfs, namecache, purge, done, vp);
1959 if (LIST_EMPTY(&vp->v_cache_src) && TAILQ_EMPTY(&vp->v_cache_dst) &&
1960 vp->v_cache_dd == NULL)
1961 return;
1962 TAILQ_INIT(&ncps);
1963 vlp = VP2VNODELOCK(vp);
1964 vlp2 = NULL;
1965 mtx_lock(vlp);
1966 retry:
1967 while (!LIST_EMPTY(&vp->v_cache_src)) {
1968 ncp = LIST_FIRST(&vp->v_cache_src);
1969 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
1970 goto retry;
1971 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
1972 }
1973 while (!TAILQ_EMPTY(&vp->v_cache_dst)) {
1974 ncp = TAILQ_FIRST(&vp->v_cache_dst);
1975 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
1976 goto retry;
1977 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
1978 }
1979 ncp = vp->v_cache_dd;
1980 if (ncp != NULL) {
1981 KASSERT(ncp->nc_flag & NCF_ISDOTDOT,
1982 ("lost dotdot link"));
1983 if (!cache_zap_locked_vnode_kl2(ncp, vp, &vlp2))
1984 goto retry;
1985 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
1986 }
1987 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge"));
1988 mtx_unlock(vlp);
1989 if (vlp2 != NULL)
1990 mtx_unlock(vlp2);
1991 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) {
1992 cache_free(ncp);
1993 }
1994 }
1995
1996 /*
1997 * Invalidate all negative entries for a particular directory vnode.
1998 */
1999 void
2000 cache_purge_negative(struct vnode *vp)
2001 {
2002 TAILQ_HEAD(, namecache) ncps;
2003 struct namecache *ncp, *nnp;
2004 struct mtx *vlp;
2005
2006 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp);
2007 SDT_PROBE1(vfs, namecache, purge_negative, done, vp);
2008 if (LIST_EMPTY(&vp->v_cache_src))
2009 return;
2010 TAILQ_INIT(&ncps);
2011 vlp = VP2VNODELOCK(vp);
2012 mtx_lock(vlp);
2013 LIST_FOREACH_SAFE(ncp, &vp->v_cache_src, nc_src, nnp) {
2014 if (!(ncp->nc_flag & NCF_NEGATIVE))
2015 continue;
2016 cache_zap_negative_locked_vnode_kl(ncp, vp);
2017 TAILQ_INSERT_TAIL(&ncps, ncp, nc_dst);
2018 }
2019 mtx_unlock(vlp);
2020 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) {
2021 cache_free(ncp);
2022 }
2023 }
2024
2025 /*
2026 * Flush all entries referencing a particular filesystem.
2027 */
2028 void
2029 cache_purgevfs(struct mount *mp, bool force)
2030 {
2031 TAILQ_HEAD(, namecache) ncps;
2032 struct mtx *vlp1, *vlp2;
2033 struct rwlock *blp;
2034 struct nchashhead *bucket;
2035 struct namecache *ncp, *nnp;
2036 u_long i, j, n_nchash;
2037 int error;
2038
2039 /* Scan hash tables for applicable entries */
2040 SDT_PROBE1(vfs, namecache, purgevfs, done, mp);
2041 if (!force && mp->mnt_nvnodelistsize <= ncpurgeminvnodes)
2042 return;
2043 TAILQ_INIT(&ncps);
2044 n_nchash = nchash + 1;
2045 vlp1 = vlp2 = NULL;
2046 for (i = 0; i < numbucketlocks; i++) {
2047 blp = (struct rwlock *)&bucketlocks[i];
2048 rw_wlock(blp);
2049 for (j = i; j < n_nchash; j += numbucketlocks) {
2050 retry:
2051 bucket = &nchashtbl[j];
2052 LIST_FOREACH_SAFE(ncp, bucket, nc_hash, nnp) {
2053 cache_assert_bucket_locked(ncp, RA_WLOCKED);
2054 if (ncp->nc_dvp->v_mount != mp)
2055 continue;
2056 error = cache_zap_wlocked_bucket_kl(ncp, blp,
2057 &vlp1, &vlp2);
2058 if (error != 0)
2059 goto retry;
2060 TAILQ_INSERT_HEAD(&ncps, ncp, nc_dst);
2061 }
2062 }
2063 rw_wunlock(blp);
2064 if (vlp1 == NULL && vlp2 == NULL)
2065 cache_maybe_yield();
2066 }
2067 if (vlp1 != NULL)
2068 mtx_unlock(vlp1);
2069 if (vlp2 != NULL)
2070 mtx_unlock(vlp2);
2071
2072 TAILQ_FOREACH_SAFE(ncp, &ncps, nc_dst, nnp) {
2073 cache_free(ncp);
2074 }
2075 }
2076
2077 /*
2078 * Perform canonical checks and cache lookup and pass on to filesystem
2079 * through the vop_cachedlookup only if needed.
2080 */
2081
2082 int
2083 vfs_cache_lookup(struct vop_lookup_args *ap)
2084 {
2085 struct vnode *dvp;
2086 int error;
2087 struct vnode **vpp = ap->a_vpp;
2088 struct componentname *cnp = ap->a_cnp;
2089 struct ucred *cred = cnp->cn_cred;
2090 int flags = cnp->cn_flags;
2091 struct thread *td = cnp->cn_thread;
2092
2093 *vpp = NULL;
2094 dvp = ap->a_dvp;
2095
2096 if (dvp->v_type != VDIR)
2097 return (ENOTDIR);
2098
2099 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
2100 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
2101 return (EROFS);
2102
2103 error = VOP_ACCESS(dvp, VEXEC, cred, td);
2104 if (error)
2105 return (error);
2106
2107 error = cache_lookup(dvp, vpp, cnp, NULL, NULL);
2108 if (error == 0)
2109 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
2110 if (error == -1)
2111 return (0);
2112 return (error);
2113 }
2114
2115 /*
2116 * XXX All of these sysctls would probably be more productive dead.
2117 */
2118 static int __read_mostly disablecwd;
2119 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0,
2120 "Disable the getcwd syscall");
2121
2122 /* Implementation of the getcwd syscall. */
2123 int
2124 sys___getcwd(struct thread *td, struct __getcwd_args *uap)
2125 {
2126
2127 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen,
2128 MAXPATHLEN));
2129 }
2130
2131 int
2132 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, size_t buflen,
2133 size_t path_max)
2134 {
2135 char *bp, *tmpbuf;
2136 struct filedesc *fdp;
2137 struct vnode *cdir, *rdir;
2138 int error;
2139
2140 if (__predict_false(disablecwd))
2141 return (ENODEV);
2142 if (__predict_false(buflen < 2))
2143 return (EINVAL);
2144 if (buflen > path_max)
2145 buflen = path_max;
2146
2147 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK);
2148 fdp = td->td_proc->p_fd;
2149 FILEDESC_SLOCK(fdp);
2150 cdir = fdp->fd_cdir;
2151 vrefact(cdir);
2152 rdir = fdp->fd_rdir;
2153 vrefact(rdir);
2154 FILEDESC_SUNLOCK(fdp);
2155 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen);
2156 vrele(rdir);
2157 vrele(cdir);
2158
2159 if (!error) {
2160 if (bufseg == UIO_SYSSPACE)
2161 bcopy(bp, buf, strlen(bp) + 1);
2162 else
2163 error = copyout(bp, buf, strlen(bp) + 1);
2164 #ifdef KTRACE
2165 if (KTRPOINT(curthread, KTR_NAMEI))
2166 ktrnamei(bp);
2167 #endif
2168 }
2169 free(tmpbuf, M_TEMP);
2170 return (error);
2171 }
2172
2173 /*
2174 * Thus begins the fullpath magic.
2175 */
2176
2177 static int __read_mostly disablefullpath;
2178 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0,
2179 "Disable the vn_fullpath function");
2180
2181 /*
2182 * Retrieve the full filesystem path that correspond to a vnode from the name
2183 * cache (if available)
2184 */
2185 int
2186 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf)
2187 {
2188 char *buf;
2189 struct filedesc *fdp;
2190 struct vnode *rdir;
2191 int error;
2192
2193 if (__predict_false(disablefullpath))
2194 return (ENODEV);
2195 if (__predict_false(vn == NULL))
2196 return (EINVAL);
2197
2198 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
2199 fdp = td->td_proc->p_fd;
2200 FILEDESC_SLOCK(fdp);
2201 rdir = fdp->fd_rdir;
2202 vrefact(rdir);
2203 FILEDESC_SUNLOCK(fdp);
2204 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN);
2205 vrele(rdir);
2206
2207 if (!error)
2208 *freebuf = buf;
2209 else
2210 free(buf, M_TEMP);
2211 return (error);
2212 }
2213
2214 /*
2215 * This function is similar to vn_fullpath, but it attempts to lookup the
2216 * pathname relative to the global root mount point. This is required for the
2217 * auditing sub-system, as audited pathnames must be absolute, relative to the
2218 * global root mount point.
2219 */
2220 int
2221 vn_fullpath_global(struct thread *td, struct vnode *vn,
2222 char **retbuf, char **freebuf)
2223 {
2224 char *buf;
2225 int error;
2226
2227 if (__predict_false(disablefullpath))
2228 return (ENODEV);
2229 if (__predict_false(vn == NULL))
2230 return (EINVAL);
2231 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
2232 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN);
2233 if (!error)
2234 *freebuf = buf;
2235 else
2236 free(buf, M_TEMP);
2237 return (error);
2238 }
2239
2240 int
2241 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen)
2242 {
2243 struct vnode *dvp;
2244 struct namecache *ncp;
2245 struct mtx *vlp;
2246 int error;
2247
2248 vlp = VP2VNODELOCK(*vp);
2249 mtx_lock(vlp);
2250 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) {
2251 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
2252 break;
2253 }
2254 if (ncp != NULL) {
2255 if (*buflen < ncp->nc_nlen) {
2256 mtx_unlock(vlp);
2257 vrele(*vp);
2258 counter_u64_add(numfullpathfail4, 1);
2259 error = ENOMEM;
2260 SDT_PROBE3(vfs, namecache, fullpath, return, error,
2261 vp, NULL);
2262 return (error);
2263 }
2264 *buflen -= ncp->nc_nlen;
2265 memcpy(buf + *buflen, ncp->nc_name, ncp->nc_nlen);
2266 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp,
2267 ncp->nc_name, vp);
2268 dvp = *vp;
2269 *vp = ncp->nc_dvp;
2270 vref(*vp);
2271 mtx_unlock(vlp);
2272 vrele(dvp);
2273 return (0);
2274 }
2275 SDT_PROBE1(vfs, namecache, fullpath, miss, vp);
2276
2277 mtx_unlock(vlp);
2278 vn_lock(*vp, LK_SHARED | LK_RETRY);
2279 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen);
2280 vput(*vp);
2281 if (error) {
2282 counter_u64_add(numfullpathfail2, 1);
2283 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL);
2284 return (error);
2285 }
2286
2287 *vp = dvp;
2288 if (dvp->v_iflag & VI_DOOMED) {
2289 /* forced unmount */
2290 vrele(dvp);
2291 error = ENOENT;
2292 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL);
2293 return (error);
2294 }
2295 /*
2296 * *vp has its use count incremented still.
2297 */
2298
2299 return (0);
2300 }
2301
2302 /*
2303 * The magic behind kern___getcwd() and vn_fullpath().
2304 */
2305 static int
2306 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
2307 char *buf, char **retbuf, u_int buflen)
2308 {
2309 int error, slash_prefixed;
2310 #ifdef KDTRACE_HOOKS
2311 struct vnode *startvp = vp;
2312 #endif
2313 struct vnode *vp1;
2314
2315 buflen--;
2316 buf[buflen] = '\0';
2317 error = 0;
2318 slash_prefixed = 0;
2319
2320 SDT_PROBE1(vfs, namecache, fullpath, entry, vp);
2321 counter_u64_add(numfullpathcalls, 1);
2322 vref(vp);
2323 if (vp->v_type != VDIR) {
2324 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen);
2325 if (error)
2326 return (error);
2327 if (buflen == 0) {
2328 vrele(vp);
2329 return (ENOMEM);
2330 }
2331 buf[--buflen] = '/';
2332 slash_prefixed = 1;
2333 }
2334 while (vp != rdir && vp != rootvnode) {
2335 /*
2336 * The vp vnode must be already fully constructed,
2337 * since it is either found in namecache or obtained
2338 * from VOP_VPTOCNP(). We may test for VV_ROOT safely
2339 * without obtaining the vnode lock.
2340 */
2341 if ((vp->v_vflag & VV_ROOT) != 0) {
2342 vn_lock(vp, LK_RETRY | LK_SHARED);
2343
2344 /*
2345 * With the vnode locked, check for races with
2346 * unmount, forced or not. Note that we
2347 * already verified that vp is not equal to
2348 * the root vnode, which means that
2349 * mnt_vnodecovered can be NULL only for the
2350 * case of unmount.
2351 */
2352 if ((vp->v_iflag & VI_DOOMED) != 0 ||
2353 (vp1 = vp->v_mount->mnt_vnodecovered) == NULL ||
2354 vp1->v_mountedhere != vp->v_mount) {
2355 vput(vp);
2356 error = ENOENT;
2357 SDT_PROBE3(vfs, namecache, fullpath, return,
2358 error, vp, NULL);
2359 break;
2360 }
2361
2362 vref(vp1);
2363 vput(vp);
2364 vp = vp1;
2365 continue;
2366 }
2367 if (vp->v_type != VDIR) {
2368 vrele(vp);
2369 counter_u64_add(numfullpathfail1, 1);
2370 error = ENOTDIR;
2371 SDT_PROBE3(vfs, namecache, fullpath, return,
2372 error, vp, NULL);
2373 break;
2374 }
2375 error = vn_vptocnp(&vp, td->td_ucred, buf, &buflen);
2376 if (error)
2377 break;
2378 if (buflen == 0) {
2379 vrele(vp);
2380 error = ENOMEM;
2381 SDT_PROBE3(vfs, namecache, fullpath, return, error,
2382 startvp, NULL);
2383 break;
2384 }
2385 buf[--buflen] = '/';
2386 slash_prefixed = 1;
2387 }
2388 if (error)
2389 return (error);
2390 if (!slash_prefixed) {
2391 if (buflen == 0) {
2392 vrele(vp);
2393 counter_u64_add(numfullpathfail4, 1);
2394 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM,
2395 startvp, NULL);
2396 return (ENOMEM);
2397 }
2398 buf[--buflen] = '/';
2399 }
2400 counter_u64_add(numfullpathfound, 1);
2401 vrele(vp);
2402
2403 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen);
2404 *retbuf = buf + buflen;
2405 return (0);
2406 }
2407
2408 struct vnode *
2409 vn_dir_dd_ino(struct vnode *vp)
2410 {
2411 struct namecache *ncp;
2412 struct vnode *ddvp;
2413 struct mtx *vlp;
2414
2415 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino");
2416 vlp = VP2VNODELOCK(vp);
2417 mtx_lock(vlp);
2418 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) {
2419 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0)
2420 continue;
2421 ddvp = ncp->nc_dvp;
2422 vhold(ddvp);
2423 mtx_unlock(vlp);
2424 if (vget(ddvp, LK_SHARED | LK_NOWAIT | LK_VNHELD, curthread))
2425 return (NULL);
2426 return (ddvp);
2427 }
2428 mtx_unlock(vlp);
2429 return (NULL);
2430 }
2431
2432 int
2433 vn_commname(struct vnode *vp, char *buf, u_int buflen)
2434 {
2435 struct namecache *ncp;
2436 struct mtx *vlp;
2437 int l;
2438
2439 vlp = VP2VNODELOCK(vp);
2440 mtx_lock(vlp);
2441 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst)
2442 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
2443 break;
2444 if (ncp == NULL) {
2445 mtx_unlock(vlp);
2446 return (ENOENT);
2447 }
2448 l = min(ncp->nc_nlen, buflen - 1);
2449 memcpy(buf, ncp->nc_name, l);
2450 mtx_unlock(vlp);
2451 buf[l] = '\0';
2452 return (0);
2453 }
2454
2455 /* ABI compat shims for old kernel modules. */
2456 #undef cache_enter
2457
2458 void cache_enter(struct vnode *dvp, struct vnode *vp,
2459 struct componentname *cnp);
2460
2461 void
2462 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp)
2463 {
2464
2465 cache_enter_time(dvp, vp, cnp, NULL, NULL);
2466 }
2467
2468 /*
2469 * This function updates path string to vnode's full global path
2470 * and checks the size of the new path string against the pathlen argument.
2471 *
2472 * Requires a locked, referenced vnode.
2473 * Vnode is re-locked on success or ENODEV, otherwise unlocked.
2474 *
2475 * If sysctl debug.disablefullpath is set, ENODEV is returned,
2476 * vnode is left locked and path remain untouched.
2477 *
2478 * If vp is a directory, the call to vn_fullpath_global() always succeeds
2479 * because it falls back to the ".." lookup if the namecache lookup fails.
2480 */
2481 int
2482 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path,
2483 u_int pathlen)
2484 {
2485 struct nameidata nd;
2486 struct vnode *vp1;
2487 char *rpath, *fbuf;
2488 int error;
2489
2490 ASSERT_VOP_ELOCKED(vp, __func__);
2491
2492 /* Return ENODEV if sysctl debug.disablefullpath==1 */
2493 if (__predict_false(disablefullpath))
2494 return (ENODEV);
2495
2496 /* Construct global filesystem path from vp. */
2497 VOP_UNLOCK(vp, 0);
2498 error = vn_fullpath_global(td, vp, &rpath, &fbuf);
2499
2500 if (error != 0) {
2501 vrele(vp);
2502 return (error);
2503 }
2504
2505 if (strlen(rpath) >= pathlen) {
2506 vrele(vp);
2507 error = ENAMETOOLONG;
2508 goto out;
2509 }
2510
2511 /*
2512 * Re-lookup the vnode by path to detect a possible rename.
2513 * As a side effect, the vnode is relocked.
2514 * If vnode was renamed, return ENOENT.
2515 */
2516 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1,
2517 UIO_SYSSPACE, path, td);
2518 error = namei(&nd);
2519 if (error != 0) {
2520 vrele(vp);
2521 goto out;
2522 }
2523 NDFREE(&nd, NDF_ONLY_PNBUF);
2524 vp1 = nd.ni_vp;
2525 vrele(vp);
2526 if (vp1 == vp)
2527 strcpy(path, rpath);
2528 else {
2529 vput(vp1);
2530 error = ENOENT;
2531 }
2532
2533 out:
2534 free(fbuf, M_TEMP);
2535 return (error);
2536 }
2537
2538 #ifdef DDB
2539 static void
2540 db_print_vpath(struct vnode *vp)
2541 {
2542
2543 while (vp != NULL) {
2544 db_printf("%p: ", vp);
2545 if (vp == rootvnode) {
2546 db_printf("/");
2547 vp = NULL;
2548 } else {
2549 if (vp->v_vflag & VV_ROOT) {
2550 db_printf("<mount point>");
2551 vp = vp->v_mount->mnt_vnodecovered;
2552 } else {
2553 struct namecache *ncp;
2554 char *ncn;
2555 int i;
2556
2557 ncp = TAILQ_FIRST(&vp->v_cache_dst);
2558 if (ncp != NULL) {
2559 ncn = ncp->nc_name;
2560 for (i = 0; i < ncp->nc_nlen; i++)
2561 db_printf("%c", *ncn++);
2562 vp = ncp->nc_dvp;
2563 } else {
2564 vp = NULL;
2565 }
2566 }
2567 }
2568 db_printf("\n");
2569 }
2570
2571 return;
2572 }
2573
2574 DB_SHOW_COMMAND(vpath, db_show_vpath)
2575 {
2576 struct vnode *vp;
2577
2578 if (!have_addr) {
2579 db_printf("usage: show vpath <struct vnode *>\n");
2580 return;
2581 }
2582
2583 vp = (struct vnode *)addr;
2584 db_print_vpath(vp);
2585 }
2586
2587 #endif
Cache object: 11c61555d0e0084975ef18ed8b453109
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