FreeBSD/Linux Kernel Cross Reference
sys/kern/vfs_cache.c
1 /*-
2 * Copyright (c) 1989, 1993, 1995
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Poul-Henning Kamp of the FreeBSD Project.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
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
30 * SUCH DAMAGE.
31 *
32 * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95
33 */
34
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37
38 #include "opt_kdtrace.h"
39 #include "opt_ktrace.h"
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/filedesc.h>
44 #include <sys/fnv_hash.h>
45 #include <sys/kernel.h>
46 #include <sys/lock.h>
47 #include <sys/malloc.h>
48 #include <sys/fcntl.h>
49 #include <sys/mount.h>
50 #include <sys/namei.h>
51 #include <sys/proc.h>
52 #include <sys/rwlock.h>
53 #include <sys/sdt.h>
54 #include <sys/syscallsubr.h>
55 #include <sys/sysctl.h>
56 #include <sys/sysproto.h>
57 #include <sys/vnode.h>
58 #ifdef KTRACE
59 #include <sys/ktrace.h>
60 #endif
61
62 #include <vm/uma.h>
63
64 SDT_PROVIDER_DECLARE(vfs);
65 SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *",
66 "struct vnode *");
67 SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *",
68 "char *");
69 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *");
70 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *",
71 "char *", "struct vnode *");
72 SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *");
73 SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int",
74 "struct vnode *", "char *");
75 SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *",
76 "struct vnode *");
77 SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative,
78 "struct vnode *", "char *");
79 SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *",
80 "char *");
81 SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *");
82 SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *");
83 SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *");
84 SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *",
85 "struct vnode *");
86 SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, "struct vnode *",
87 "char *");
88
89 /*
90 * This structure describes the elements in the cache of recent
91 * names looked up by namei.
92 */
93
94 struct namecache {
95 LIST_ENTRY(namecache) nc_hash; /* hash chain */
96 LIST_ENTRY(namecache) nc_src; /* source vnode list */
97 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */
98 struct vnode *nc_dvp; /* vnode of parent of name */
99 struct vnode *nc_vp; /* vnode the name refers to */
100 u_char nc_flag; /* flag bits */
101 u_char nc_nlen; /* length of name */
102 char nc_name[0]; /* segment name + nul */
103 };
104
105 /*
106 * struct namecache_ts repeats struct namecache layout up to the
107 * nc_nlen member.
108 * struct namecache_ts is used in place of struct namecache when time(s) need
109 * to be stored. The nc_dotdottime field is used when a cache entry is mapping
110 * both a non-dotdot directory name plus dotdot for the directory's
111 * parent.
112 */
113 struct namecache_ts {
114 LIST_ENTRY(namecache) nc_hash; /* hash chain */
115 LIST_ENTRY(namecache) nc_src; /* source vnode list */
116 TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */
117 struct vnode *nc_dvp; /* vnode of parent of name */
118 struct vnode *nc_vp; /* vnode the name refers to */
119 u_char nc_flag; /* flag bits */
120 u_char nc_nlen; /* length of name */
121 struct timespec nc_time; /* timespec provided by fs */
122 struct timespec nc_dotdottime; /* dotdot timespec provided by fs */
123 int nc_ticks; /* ticks value when entry was added */
124 char nc_name[0]; /* segment name + nul */
125 };
126
127 /*
128 * Flags in namecache.nc_flag
129 */
130 #define NCF_WHITE 0x01
131 #define NCF_ISDOTDOT 0x02
132 #define NCF_TS 0x04
133 #define NCF_DTS 0x08
134
135 /*
136 * Name caching works as follows:
137 *
138 * Names found by directory scans are retained in a cache
139 * for future reference. It is managed LRU, so frequently
140 * used names will hang around. Cache is indexed by hash value
141 * obtained from (vp, name) where vp refers to the directory
142 * containing name.
143 *
144 * If it is a "negative" entry, (i.e. for a name that is known NOT to
145 * exist) the vnode pointer will be NULL.
146 *
147 * Upon reaching the last segment of a path, if the reference
148 * is for DELETE, or NOCACHE is set (rewrite), and the
149 * name is located in the cache, it will be dropped.
150 */
151
152 /*
153 * Structures associated with name caching.
154 */
155 #define NCHHASH(hash) \
156 (&nchashtbl[(hash) & nchash])
157 static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */
158 static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */
159 static u_long nchash; /* size of hash table */
160 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0,
161 "Size of namecache hash table");
162 static u_long ncnegfactor = 16; /* ratio of negative entries */
163 SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0,
164 "Ratio of negative namecache entries");
165 static u_long numneg; /* number of negative entries allocated */
166 SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0,
167 "Number of negative entries in namecache");
168 static u_long numcache; /* number of cache entries allocated */
169 SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0,
170 "Number of namecache entries");
171 static u_long numcachehv; /* number of cache entries with vnodes held */
172 SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0,
173 "Number of namecache entries with vnodes held");
174 static u_int ncsizefactor = 2;
175 SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0,
176 "Size factor for namecache");
177
178 struct nchstats nchstats; /* cache effectiveness statistics */
179
180 static struct rwlock cache_lock;
181 RW_SYSINIT(vfscache, &cache_lock, "Name Cache");
182
183 #define CACHE_UPGRADE_LOCK() rw_try_upgrade(&cache_lock)
184 #define CACHE_RLOCK() rw_rlock(&cache_lock)
185 #define CACHE_RUNLOCK() rw_runlock(&cache_lock)
186 #define CACHE_WLOCK() rw_wlock(&cache_lock)
187 #define CACHE_WUNLOCK() rw_wunlock(&cache_lock)
188
189 /*
190 * UMA zones for the VFS cache.
191 *
192 * The small cache is used for entries with short names, which are the
193 * most common. The large cache is used for entries which are too big to
194 * fit in the small cache.
195 */
196 static uma_zone_t cache_zone_small;
197 static uma_zone_t cache_zone_small_ts;
198 static uma_zone_t cache_zone_large;
199 static uma_zone_t cache_zone_large_ts;
200
201 #define CACHE_PATH_CUTOFF 35
202
203 static struct namecache *
204 cache_alloc(int len, int ts)
205 {
206
207 if (len > CACHE_PATH_CUTOFF) {
208 if (ts)
209 return (uma_zalloc(cache_zone_large_ts, M_WAITOK));
210 else
211 return (uma_zalloc(cache_zone_large, M_WAITOK));
212 }
213 if (ts)
214 return (uma_zalloc(cache_zone_small_ts, M_WAITOK));
215 else
216 return (uma_zalloc(cache_zone_small, M_WAITOK));
217 }
218
219 static void
220 cache_free(struct namecache *ncp)
221 {
222 int ts;
223
224 if (ncp == NULL)
225 return;
226 ts = ncp->nc_flag & NCF_TS;
227 if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) {
228 if (ts)
229 uma_zfree(cache_zone_small_ts, ncp);
230 else
231 uma_zfree(cache_zone_small, ncp);
232 } else if (ts)
233 uma_zfree(cache_zone_large_ts, ncp);
234 else
235 uma_zfree(cache_zone_large, ncp);
236 }
237
238 static char *
239 nc_get_name(struct namecache *ncp)
240 {
241 struct namecache_ts *ncp_ts;
242
243 if ((ncp->nc_flag & NCF_TS) == 0)
244 return (ncp->nc_name);
245 ncp_ts = (struct namecache_ts *)ncp;
246 return (ncp_ts->nc_name);
247 }
248
249 static void
250 cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp)
251 {
252
253 KASSERT((ncp->nc_flag & NCF_TS) != 0 ||
254 (tsp == NULL && ticksp == NULL),
255 ("No NCF_TS"));
256
257 if (tsp != NULL)
258 *tsp = ((struct namecache_ts *)ncp)->nc_time;
259 if (ticksp != NULL)
260 *ticksp = ((struct namecache_ts *)ncp)->nc_ticks;
261 }
262
263 static int doingcache = 1; /* 1 => enable the cache */
264 SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0,
265 "VFS namecache enabled");
266
267 /* Export size information to userland */
268 SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR,
269 sizeof(struct namecache), "sizeof(struct namecache)");
270
271 /*
272 * The new name cache statistics
273 */
274 static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0,
275 "Name cache statistics");
276 #define STATNODE(mode, name, var, descr) \
277 SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, descr);
278 STATNODE(CTLFLAG_RD, numneg, &numneg, "Number of negative cache entries");
279 STATNODE(CTLFLAG_RD, numcache, &numcache, "Number of cache entries");
280 static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls,
281 "Number of cache lookups");
282 static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits,
283 "Number of '.' hits");
284 static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits,
285 "Number of '..' hits");
286 static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks,
287 "Number of checks in lookup");
288 static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss,
289 "Number of cache misses");
290 static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap,
291 "Number of cache misses we do not want to cache");
292 static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps,
293 "Number of cache hits (positive) we do not want to cache");
294 static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits,
295 "Number of cache hits (positive)");
296 static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps,
297 "Number of cache hits (negative) we do not want to cache");
298 static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits,
299 "Number of cache hits (negative)");
300 static u_long numupgrades; STATNODE(CTLFLAG_RD, numupgrades, &numupgrades,
301 "Number of updates of the cache after lookup (write lock + retry)");
302
303 SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD | CTLFLAG_MPSAFE,
304 &nchstats, sizeof(nchstats), "LU",
305 "VFS cache effectiveness statistics");
306
307 static void cache_zap(struct namecache *ncp);
308 static int vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf,
309 u_int *buflen);
310 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
311 char *buf, char **retbuf, u_int buflen);
312
313 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries");
314
315 #ifdef DIAGNOSTIC
316 /*
317 * Grab an atomic snapshot of the name cache hash chain lengths
318 */
319 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL,
320 "hash table stats");
321
322 static int
323 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS)
324 {
325 struct nchashhead *ncpp;
326 struct namecache *ncp;
327 int i, error, n_nchash, *cntbuf;
328
329 retry:
330 n_nchash = nchash + 1; /* nchash is max index, not count */
331 if (!req->oldptr)
332 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int));
333 cntbuf = malloc(n_nchash * sizeof(int), M_TEMP, M_ZERO | M_WAITOK);
334 CACHE_RLOCK();
335 if (n_nchash != nchash + 1) {
336 CACHE_RUNLOCK();
337 free(cntbuf, M_TEMP);
338 goto retry;
339 }
340 /* Scan hash tables counting entries */
341 for (ncpp = nchashtbl, i = 0; i < n_nchash; ncpp++, i++)
342 LIST_FOREACH(ncp, ncpp, nc_hash)
343 cntbuf[i]++;
344 CACHE_RUNLOCK();
345 for (error = 0, i = 0; i < n_nchash; i++)
346 if ((error = SYSCTL_OUT(req, &cntbuf[i], sizeof(int))) != 0)
347 break;
348 free(cntbuf, M_TEMP);
349 return (error);
350 }
351 SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD|
352 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int",
353 "nchash chain lengths");
354
355 static int
356 sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS)
357 {
358 int error;
359 struct nchashhead *ncpp;
360 struct namecache *ncp;
361 int n_nchash;
362 int count, maxlength, used, pct;
363
364 if (!req->oldptr)
365 return SYSCTL_OUT(req, 0, 4 * sizeof(int));
366
367 n_nchash = nchash + 1; /* nchash is max index, not count */
368 used = 0;
369 maxlength = 0;
370
371 /* Scan hash tables for applicable entries */
372 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
373 count = 0;
374 CACHE_RLOCK();
375 LIST_FOREACH(ncp, ncpp, nc_hash) {
376 count++;
377 }
378 CACHE_RUNLOCK();
379 if (count)
380 used++;
381 if (maxlength < count)
382 maxlength = count;
383 }
384 n_nchash = nchash + 1;
385 pct = (used * 100) / (n_nchash / 100);
386 error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash));
387 if (error)
388 return (error);
389 error = SYSCTL_OUT(req, &used, sizeof(used));
390 if (error)
391 return (error);
392 error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength));
393 if (error)
394 return (error);
395 error = SYSCTL_OUT(req, &pct, sizeof(pct));
396 if (error)
397 return (error);
398 return (0);
399 }
400 SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD|
401 CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I",
402 "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)");
403 #endif
404
405 /*
406 * cache_zap():
407 *
408 * Removes a namecache entry from cache, whether it contains an actual
409 * pointer to a vnode or if it is just a negative cache entry.
410 */
411 static void
412 cache_zap(struct namecache *ncp)
413 {
414 struct vnode *vp;
415
416 rw_assert(&cache_lock, RA_WLOCKED);
417 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp);
418 if (ncp->nc_vp != NULL) {
419 SDT_PROBE3(vfs, namecache, zap, done, ncp->nc_dvp,
420 nc_get_name(ncp), ncp->nc_vp);
421 } else {
422 SDT_PROBE2(vfs, namecache, zap_negative, done, ncp->nc_dvp,
423 nc_get_name(ncp));
424 }
425 vp = NULL;
426 LIST_REMOVE(ncp, nc_hash);
427 if (ncp->nc_flag & NCF_ISDOTDOT) {
428 if (ncp == ncp->nc_dvp->v_cache_dd)
429 ncp->nc_dvp->v_cache_dd = NULL;
430 } else {
431 LIST_REMOVE(ncp, nc_src);
432 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) {
433 vp = ncp->nc_dvp;
434 numcachehv--;
435 }
436 }
437 if (ncp->nc_vp) {
438 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst);
439 if (ncp == ncp->nc_vp->v_cache_dd)
440 ncp->nc_vp->v_cache_dd = NULL;
441 } else {
442 TAILQ_REMOVE(&ncneg, ncp, nc_dst);
443 numneg--;
444 }
445 numcache--;
446 cache_free(ncp);
447 if (vp != NULL)
448 vdrop(vp);
449 }
450
451 /*
452 * Lookup an entry in the cache
453 *
454 * Lookup is called with dvp pointing to the directory to search,
455 * cnp pointing to the name of the entry being sought. If the lookup
456 * succeeds, the vnode is returned in *vpp, and a status of -1 is
457 * returned. If the lookup determines that the name does not exist
458 * (negative caching), a status of ENOENT is returned. If the lookup
459 * fails, a status of zero is returned. If the directory vnode is
460 * recycled out from under us due to a forced unmount, a status of
461 * ENOENT is returned.
462 *
463 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is
464 * unlocked. If we're looking up . an extra ref is taken, but the lock is
465 * not recursively acquired.
466 */
467
468 int
469 cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp,
470 struct timespec *tsp, int *ticksp)
471 {
472 struct namecache *ncp;
473 uint32_t hash;
474 int error, ltype, wlocked;
475
476 if (!doingcache) {
477 cnp->cn_flags &= ~MAKEENTRY;
478 return (0);
479 }
480 retry:
481 CACHE_RLOCK();
482 wlocked = 0;
483 numcalls++;
484 error = 0;
485
486 retry_wlocked:
487 if (cnp->cn_nameptr[0] == '.') {
488 if (cnp->cn_namelen == 1) {
489 *vpp = dvp;
490 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .",
491 dvp, cnp->cn_nameptr);
492 dothits++;
493 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, ".", *vpp);
494 if (tsp != NULL)
495 timespecclear(tsp);
496 if (ticksp != NULL)
497 *ticksp = ticks;
498 goto success;
499 }
500 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
501 dotdothits++;
502 if (dvp->v_cache_dd == NULL) {
503 SDT_PROBE3(vfs, namecache, lookup, miss, dvp,
504 "..", NULL);
505 goto unlock;
506 }
507 if ((cnp->cn_flags & MAKEENTRY) == 0) {
508 if (!wlocked && !CACHE_UPGRADE_LOCK())
509 goto wlock;
510 if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT)
511 cache_zap(dvp->v_cache_dd);
512 dvp->v_cache_dd = NULL;
513 CACHE_WUNLOCK();
514 return (0);
515 }
516 ncp = dvp->v_cache_dd;
517 if (ncp->nc_flag & NCF_ISDOTDOT)
518 *vpp = ncp->nc_vp;
519 else
520 *vpp = ncp->nc_dvp;
521 /* Return failure if negative entry was found. */
522 if (*vpp == NULL)
523 goto negative_success;
524 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..",
525 dvp, cnp->cn_nameptr, *vpp);
526 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, "..",
527 *vpp);
528 cache_out_ts(ncp, tsp, ticksp);
529 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) ==
530 NCF_DTS && tsp != NULL)
531 *tsp = ((struct namecache_ts *)ncp)->
532 nc_dotdottime;
533 goto success;
534 }
535 }
536
537 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT);
538 hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
539 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
540 numchecks++;
541 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
542 !bcmp(nc_get_name(ncp), cnp->cn_nameptr, ncp->nc_nlen))
543 break;
544 }
545
546 /* We failed to find an entry */
547 if (ncp == NULL) {
548 SDT_PROBE3(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr,
549 NULL);
550 if ((cnp->cn_flags & MAKEENTRY) == 0) {
551 nummisszap++;
552 } else {
553 nummiss++;
554 }
555 nchstats.ncs_miss++;
556 goto unlock;
557 }
558
559 /* We don't want to have an entry, so dump it */
560 if ((cnp->cn_flags & MAKEENTRY) == 0) {
561 numposzaps++;
562 nchstats.ncs_badhits++;
563 if (!wlocked && !CACHE_UPGRADE_LOCK())
564 goto wlock;
565 cache_zap(ncp);
566 CACHE_WUNLOCK();
567 return (0);
568 }
569
570 /* We found a "positive" match, return the vnode */
571 if (ncp->nc_vp) {
572 numposhits++;
573 nchstats.ncs_goodhits++;
574 *vpp = ncp->nc_vp;
575 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p",
576 dvp, cnp->cn_nameptr, *vpp, ncp);
577 SDT_PROBE3(vfs, namecache, lookup, hit, dvp, nc_get_name(ncp),
578 *vpp);
579 cache_out_ts(ncp, tsp, ticksp);
580 goto success;
581 }
582
583 negative_success:
584 /* We found a negative match, and want to create it, so purge */
585 if (cnp->cn_nameiop == CREATE) {
586 numnegzaps++;
587 nchstats.ncs_badhits++;
588 if (!wlocked && !CACHE_UPGRADE_LOCK())
589 goto wlock;
590 cache_zap(ncp);
591 CACHE_WUNLOCK();
592 return (0);
593 }
594
595 if (!wlocked && !CACHE_UPGRADE_LOCK())
596 goto wlock;
597 numneghits++;
598 /*
599 * We found a "negative" match, so we shift it to the end of
600 * the "negative" cache entries queue to satisfy LRU. Also,
601 * check to see if the entry is a whiteout; indicate this to
602 * the componentname, if so.
603 */
604 TAILQ_REMOVE(&ncneg, ncp, nc_dst);
605 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
606 nchstats.ncs_neghits++;
607 if (ncp->nc_flag & NCF_WHITE)
608 cnp->cn_flags |= ISWHITEOUT;
609 SDT_PROBE2(vfs, namecache, lookup, hit__negative, dvp,
610 nc_get_name(ncp));
611 cache_out_ts(ncp, tsp, ticksp);
612 CACHE_WUNLOCK();
613 return (ENOENT);
614
615 wlock:
616 /*
617 * We need to update the cache after our lookup, so upgrade to
618 * a write lock and retry the operation.
619 */
620 CACHE_RUNLOCK();
621 CACHE_WLOCK();
622 numupgrades++;
623 wlocked = 1;
624 goto retry_wlocked;
625
626 success:
627 /*
628 * On success we return a locked and ref'd vnode as per the lookup
629 * protocol.
630 */
631 if (dvp == *vpp) { /* lookup on "." */
632 VREF(*vpp);
633 if (wlocked)
634 CACHE_WUNLOCK();
635 else
636 CACHE_RUNLOCK();
637 /*
638 * When we lookup "." we still can be asked to lock it
639 * differently...
640 */
641 ltype = cnp->cn_lkflags & LK_TYPE_MASK;
642 if (ltype != VOP_ISLOCKED(*vpp)) {
643 if (ltype == LK_EXCLUSIVE) {
644 vn_lock(*vpp, LK_UPGRADE | LK_RETRY);
645 if ((*vpp)->v_iflag & VI_DOOMED) {
646 /* forced unmount */
647 vrele(*vpp);
648 *vpp = NULL;
649 return (ENOENT);
650 }
651 } else
652 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY);
653 }
654 return (-1);
655 }
656 ltype = 0; /* silence gcc warning */
657 if (cnp->cn_flags & ISDOTDOT) {
658 ltype = VOP_ISLOCKED(dvp);
659 VOP_UNLOCK(dvp, 0);
660 }
661 VI_LOCK(*vpp);
662 if (wlocked)
663 CACHE_WUNLOCK();
664 else
665 CACHE_RUNLOCK();
666 error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread);
667 if (cnp->cn_flags & ISDOTDOT) {
668 vn_lock(dvp, ltype | LK_RETRY);
669 if (dvp->v_iflag & VI_DOOMED) {
670 if (error == 0)
671 vput(*vpp);
672 *vpp = NULL;
673 return (ENOENT);
674 }
675 }
676 if (error) {
677 *vpp = NULL;
678 goto retry;
679 }
680 if ((cnp->cn_flags & ISLASTCN) &&
681 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) {
682 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup");
683 }
684 return (-1);
685
686 unlock:
687 if (wlocked)
688 CACHE_WUNLOCK();
689 else
690 CACHE_RUNLOCK();
691 return (0);
692 }
693
694 /*
695 * Add an entry to the cache.
696 */
697 void
698 cache_enter_time(struct vnode *dvp, struct vnode *vp, struct componentname *cnp,
699 struct timespec *tsp, struct timespec *dtsp)
700 {
701 struct namecache *ncp, *n2;
702 struct namecache_ts *n3;
703 struct nchashhead *ncpp;
704 uint32_t hash;
705 int flag;
706 int hold;
707 int zap;
708 int len;
709
710 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr);
711 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp,
712 ("cache_enter: Adding a doomed vnode"));
713 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp,
714 ("cache_enter: Doomed vnode used as src"));
715
716 if (!doingcache)
717 return;
718
719 /*
720 * Avoid blowout in namecache entries.
721 */
722 if (numcache >= desiredvnodes * ncsizefactor)
723 return;
724
725 flag = 0;
726 if (cnp->cn_nameptr[0] == '.') {
727 if (cnp->cn_namelen == 1)
728 return;
729 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
730 CACHE_WLOCK();
731 /*
732 * If dotdot entry already exists, just retarget it
733 * to new parent vnode, otherwise continue with new
734 * namecache entry allocation.
735 */
736 if ((ncp = dvp->v_cache_dd) != NULL &&
737 ncp->nc_flag & NCF_ISDOTDOT) {
738 KASSERT(ncp->nc_dvp == dvp,
739 ("wrong isdotdot parent"));
740 if (ncp->nc_vp != NULL) {
741 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst,
742 ncp, nc_dst);
743 } else {
744 TAILQ_REMOVE(&ncneg, ncp, nc_dst);
745 numneg--;
746 }
747 if (vp != NULL) {
748 TAILQ_INSERT_HEAD(&vp->v_cache_dst,
749 ncp, nc_dst);
750 } else {
751 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
752 numneg++;
753 }
754 ncp->nc_vp = vp;
755 CACHE_WUNLOCK();
756 return;
757 }
758 dvp->v_cache_dd = NULL;
759 SDT_PROBE3(vfs, namecache, enter, done, dvp, "..", vp);
760 CACHE_WUNLOCK();
761 flag = NCF_ISDOTDOT;
762 }
763 }
764
765 hold = 0;
766 zap = 0;
767
768 /*
769 * Calculate the hash key and setup as much of the new
770 * namecache entry as possible before acquiring the lock.
771 */
772 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL);
773 ncp->nc_vp = vp;
774 ncp->nc_dvp = dvp;
775 ncp->nc_flag = flag;
776 if (tsp != NULL) {
777 n3 = (struct namecache_ts *)ncp;
778 n3->nc_time = *tsp;
779 n3->nc_ticks = ticks;
780 n3->nc_flag |= NCF_TS;
781 if (dtsp != NULL) {
782 n3->nc_dotdottime = *dtsp;
783 n3->nc_flag |= NCF_DTS;
784 }
785 }
786 len = ncp->nc_nlen = cnp->cn_namelen;
787 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT);
788 strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1);
789 hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
790 CACHE_WLOCK();
791
792 /*
793 * See if this vnode or negative entry is already in the cache
794 * with this name. This can happen with concurrent lookups of
795 * the same path name.
796 */
797 ncpp = NCHHASH(hash);
798 LIST_FOREACH(n2, ncpp, nc_hash) {
799 if (n2->nc_dvp == dvp &&
800 n2->nc_nlen == cnp->cn_namelen &&
801 !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) {
802 if (tsp != NULL) {
803 KASSERT((n2->nc_flag & NCF_TS) != 0,
804 ("no NCF_TS"));
805 n3 = (struct namecache_ts *)n2;
806 n3->nc_time =
807 ((struct namecache_ts *)ncp)->nc_time;
808 n3->nc_ticks =
809 ((struct namecache_ts *)ncp)->nc_ticks;
810 if (dtsp != NULL) {
811 n3->nc_dotdottime =
812 ((struct namecache_ts *)ncp)->
813 nc_dotdottime;
814 n3->nc_flag |= NCF_DTS;
815 }
816 }
817 CACHE_WUNLOCK();
818 cache_free(ncp);
819 return;
820 }
821 }
822
823 if (flag == NCF_ISDOTDOT) {
824 /*
825 * See if we are trying to add .. entry, but some other lookup
826 * has populated v_cache_dd pointer already.
827 */
828 if (dvp->v_cache_dd != NULL) {
829 CACHE_WUNLOCK();
830 cache_free(ncp);
831 return;
832 }
833 KASSERT(vp == NULL || vp->v_type == VDIR,
834 ("wrong vnode type %p", vp));
835 dvp->v_cache_dd = ncp;
836 }
837
838 numcache++;
839 if (vp == NULL) {
840 numneg++;
841 if (cnp->cn_flags & ISWHITEOUT)
842 ncp->nc_flag |= NCF_WHITE;
843 } else if (vp->v_type == VDIR) {
844 if (flag != NCF_ISDOTDOT) {
845 /*
846 * For this case, the cache entry maps both the
847 * directory name in it and the name ".." for the
848 * directory's parent.
849 */
850 if ((n2 = vp->v_cache_dd) != NULL &&
851 (n2->nc_flag & NCF_ISDOTDOT) != 0)
852 cache_zap(n2);
853 vp->v_cache_dd = ncp;
854 }
855 } else {
856 vp->v_cache_dd = NULL;
857 }
858
859 /*
860 * Insert the new namecache entry into the appropriate chain
861 * within the cache entries table.
862 */
863 LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
864 if (flag != NCF_ISDOTDOT) {
865 if (LIST_EMPTY(&dvp->v_cache_src)) {
866 hold = 1;
867 numcachehv++;
868 }
869 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src);
870 }
871
872 /*
873 * If the entry is "negative", we place it into the
874 * "negative" cache queue, otherwise, we place it into the
875 * destination vnode's cache entries queue.
876 */
877 if (vp != NULL) {
878 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst);
879 SDT_PROBE3(vfs, namecache, enter, done, dvp, nc_get_name(ncp),
880 vp);
881 } else {
882 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
883 SDT_PROBE2(vfs, namecache, enter_negative, done, dvp,
884 nc_get_name(ncp));
885 }
886 if (numneg * ncnegfactor > numcache) {
887 ncp = TAILQ_FIRST(&ncneg);
888 KASSERT(ncp->nc_vp == NULL, ("ncp %p vp %p on ncneg",
889 ncp, ncp->nc_vp));
890 zap = 1;
891 }
892 if (hold)
893 vhold(dvp);
894 if (zap)
895 cache_zap(ncp);
896 CACHE_WUNLOCK();
897 }
898
899 /*
900 * Name cache initialization, from vfs_init() when we are booting
901 */
902 static void
903 nchinit(void *dummy __unused)
904 {
905
906 TAILQ_INIT(&ncneg);
907
908 cache_zone_small = uma_zcreate("S VFS Cache",
909 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1,
910 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache),
911 UMA_ZONE_ZINIT);
912 cache_zone_small_ts = uma_zcreate("STS VFS Cache",
913 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1,
914 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts),
915 UMA_ZONE_ZINIT);
916 cache_zone_large = uma_zcreate("L VFS Cache",
917 sizeof(struct namecache) + NAME_MAX + 1,
918 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache),
919 UMA_ZONE_ZINIT);
920 cache_zone_large_ts = uma_zcreate("LTS VFS Cache",
921 sizeof(struct namecache_ts) + NAME_MAX + 1,
922 NULL, NULL, NULL, NULL, UMA_ALIGNOF(struct namecache_ts),
923 UMA_ZONE_ZINIT);
924
925 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash);
926 }
927 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
928
929 void
930 cache_changesize(int newmaxvnodes)
931 {
932 struct nchashhead *new_nchashtbl, *old_nchashtbl;
933 u_long new_nchash, old_nchash;
934 struct namecache *ncp;
935 uint32_t hash;
936 int i;
937
938 new_nchashtbl = hashinit(newmaxvnodes * 2, M_VFSCACHE, &new_nchash);
939 /* If same hash table size, nothing to do */
940 if (nchash == new_nchash) {
941 free(new_nchashtbl, M_VFSCACHE);
942 return;
943 }
944 /*
945 * Move everything from the old hash table to the new table.
946 * None of the namecache entries in the table can be removed
947 * because to do so, they have to be removed from the hash table.
948 */
949 CACHE_WLOCK();
950 old_nchashtbl = nchashtbl;
951 old_nchash = nchash;
952 nchashtbl = new_nchashtbl;
953 nchash = new_nchash;
954 for (i = 0; i <= old_nchash; i++) {
955 while ((ncp = LIST_FIRST(&old_nchashtbl[i])) != NULL) {
956 hash = fnv_32_buf(nc_get_name(ncp), ncp->nc_nlen,
957 FNV1_32_INIT);
958 hash = fnv_32_buf(&ncp->nc_dvp, sizeof(ncp->nc_dvp),
959 hash);
960 LIST_REMOVE(ncp, nc_hash);
961 LIST_INSERT_HEAD(NCHHASH(hash), ncp, nc_hash);
962 }
963 }
964 CACHE_WUNLOCK();
965 free(old_nchashtbl, M_VFSCACHE);
966 }
967
968 /*
969 * Invalidate all entries to a particular vnode.
970 */
971 void
972 cache_purge(struct vnode *vp)
973 {
974
975 CTR1(KTR_VFS, "cache_purge(%p)", vp);
976 SDT_PROBE1(vfs, namecache, purge, done, vp);
977 CACHE_WLOCK();
978 while (!LIST_EMPTY(&vp->v_cache_src))
979 cache_zap(LIST_FIRST(&vp->v_cache_src));
980 while (!TAILQ_EMPTY(&vp->v_cache_dst))
981 cache_zap(TAILQ_FIRST(&vp->v_cache_dst));
982 if (vp->v_cache_dd != NULL) {
983 KASSERT(vp->v_cache_dd->nc_flag & NCF_ISDOTDOT,
984 ("lost dotdot link"));
985 cache_zap(vp->v_cache_dd);
986 }
987 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge"));
988 CACHE_WUNLOCK();
989 }
990
991 /*
992 * Invalidate all negative entries for a particular directory vnode.
993 */
994 void
995 cache_purge_negative(struct vnode *vp)
996 {
997 struct namecache *cp, *ncp;
998
999 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp);
1000 SDT_PROBE1(vfs, namecache, purge_negative, done, vp);
1001 CACHE_WLOCK();
1002 LIST_FOREACH_SAFE(cp, &vp->v_cache_src, nc_src, ncp) {
1003 if (cp->nc_vp == NULL)
1004 cache_zap(cp);
1005 }
1006 CACHE_WUNLOCK();
1007 }
1008
1009 /*
1010 * Flush all entries referencing a particular filesystem.
1011 */
1012 void
1013 cache_purgevfs(struct mount *mp)
1014 {
1015 struct nchashhead *ncpp;
1016 struct namecache *ncp, *nnp;
1017
1018 /* Scan hash tables for applicable entries */
1019 SDT_PROBE1(vfs, namecache, purgevfs, done, mp);
1020 CACHE_WLOCK();
1021 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) {
1022 LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) {
1023 if (ncp->nc_dvp->v_mount == mp)
1024 cache_zap(ncp);
1025 }
1026 }
1027 CACHE_WUNLOCK();
1028 }
1029
1030 /*
1031 * Perform canonical checks and cache lookup and pass on to filesystem
1032 * through the vop_cachedlookup only if needed.
1033 */
1034
1035 int
1036 vfs_cache_lookup(struct vop_lookup_args *ap)
1037 {
1038 struct vnode *dvp;
1039 int error;
1040 struct vnode **vpp = ap->a_vpp;
1041 struct componentname *cnp = ap->a_cnp;
1042 struct ucred *cred = cnp->cn_cred;
1043 int flags = cnp->cn_flags;
1044 struct thread *td = cnp->cn_thread;
1045
1046 *vpp = NULL;
1047 dvp = ap->a_dvp;
1048
1049 if (dvp->v_type != VDIR)
1050 return (ENOTDIR);
1051
1052 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
1053 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
1054 return (EROFS);
1055
1056 error = VOP_ACCESS(dvp, VEXEC, cred, td);
1057 if (error)
1058 return (error);
1059
1060 error = cache_lookup(dvp, vpp, cnp, NULL, NULL);
1061 if (error == 0)
1062 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
1063 if (error == -1)
1064 return (0);
1065 return (error);
1066 }
1067
1068 /*
1069 * XXX All of these sysctls would probably be more productive dead.
1070 */
1071 static int disablecwd;
1072 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0,
1073 "Disable the getcwd syscall");
1074
1075 /* Implementation of the getcwd syscall. */
1076 int
1077 sys___getcwd(struct thread *td, struct __getcwd_args *uap)
1078 {
1079
1080 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen,
1081 MAXPATHLEN));
1082 }
1083
1084 int
1085 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, u_int buflen,
1086 u_int path_max)
1087 {
1088 char *bp, *tmpbuf;
1089 struct filedesc *fdp;
1090 struct vnode *cdir, *rdir;
1091 int error;
1092
1093 if (disablecwd)
1094 return (ENODEV);
1095 if (buflen < 2)
1096 return (EINVAL);
1097 if (buflen > path_max)
1098 buflen = path_max;
1099
1100 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK);
1101 fdp = td->td_proc->p_fd;
1102 FILEDESC_SLOCK(fdp);
1103 cdir = fdp->fd_cdir;
1104 VREF(cdir);
1105 rdir = fdp->fd_rdir;
1106 VREF(rdir);
1107 FILEDESC_SUNLOCK(fdp);
1108 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen);
1109 vrele(rdir);
1110 vrele(cdir);
1111
1112 if (!error) {
1113 if (bufseg == UIO_SYSSPACE)
1114 bcopy(bp, buf, strlen(bp) + 1);
1115 else
1116 error = copyout(bp, buf, strlen(bp) + 1);
1117 #ifdef KTRACE
1118 if (KTRPOINT(curthread, KTR_NAMEI))
1119 ktrnamei(bp);
1120 #endif
1121 }
1122 free(tmpbuf, M_TEMP);
1123 return (error);
1124 }
1125
1126 /*
1127 * Thus begins the fullpath magic.
1128 */
1129
1130 #undef STATNODE
1131 #define STATNODE(name, descr) \
1132 static u_int name; \
1133 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr)
1134
1135 static int disablefullpath;
1136 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0,
1137 "Disable the vn_fullpath function");
1138
1139 /* These count for kern___getcwd(), too. */
1140 STATNODE(numfullpathcalls, "Number of fullpath search calls");
1141 STATNODE(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)");
1142 STATNODE(numfullpathfail2,
1143 "Number of fullpath search errors (VOP_VPTOCNP failures)");
1144 STATNODE(numfullpathfail4, "Number of fullpath search errors (ENOMEM)");
1145 STATNODE(numfullpathfound, "Number of successful fullpath calls");
1146
1147 /*
1148 * Retrieve the full filesystem path that correspond to a vnode from the name
1149 * cache (if available)
1150 */
1151 int
1152 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf)
1153 {
1154 char *buf;
1155 struct filedesc *fdp;
1156 struct vnode *rdir;
1157 int error;
1158
1159 if (disablefullpath)
1160 return (ENODEV);
1161 if (vn == NULL)
1162 return (EINVAL);
1163
1164 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1165 fdp = td->td_proc->p_fd;
1166 FILEDESC_SLOCK(fdp);
1167 rdir = fdp->fd_rdir;
1168 VREF(rdir);
1169 FILEDESC_SUNLOCK(fdp);
1170 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN);
1171 vrele(rdir);
1172
1173 if (!error)
1174 *freebuf = buf;
1175 else
1176 free(buf, M_TEMP);
1177 return (error);
1178 }
1179
1180 /*
1181 * This function is similar to vn_fullpath, but it attempts to lookup the
1182 * pathname relative to the global root mount point. This is required for the
1183 * auditing sub-system, as audited pathnames must be absolute, relative to the
1184 * global root mount point.
1185 */
1186 int
1187 vn_fullpath_global(struct thread *td, struct vnode *vn,
1188 char **retbuf, char **freebuf)
1189 {
1190 char *buf;
1191 int error;
1192
1193 if (disablefullpath)
1194 return (ENODEV);
1195 if (vn == NULL)
1196 return (EINVAL);
1197 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1198 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN);
1199 if (!error)
1200 *freebuf = buf;
1201 else
1202 free(buf, M_TEMP);
1203 return (error);
1204 }
1205
1206 int
1207 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen)
1208 {
1209 int error;
1210
1211 CACHE_RLOCK();
1212 error = vn_vptocnp_locked(vp, cred, buf, buflen);
1213 if (error == 0)
1214 CACHE_RUNLOCK();
1215 return (error);
1216 }
1217
1218 static int
1219 vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf,
1220 u_int *buflen)
1221 {
1222 struct vnode *dvp;
1223 struct namecache *ncp;
1224 int error;
1225
1226 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) {
1227 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
1228 break;
1229 }
1230 if (ncp != NULL) {
1231 if (*buflen < ncp->nc_nlen) {
1232 CACHE_RUNLOCK();
1233 vrele(*vp);
1234 numfullpathfail4++;
1235 error = ENOMEM;
1236 SDT_PROBE3(vfs, namecache, fullpath, return, error,
1237 vp, NULL);
1238 return (error);
1239 }
1240 *buflen -= ncp->nc_nlen;
1241 memcpy(buf + *buflen, nc_get_name(ncp), ncp->nc_nlen);
1242 SDT_PROBE3(vfs, namecache, fullpath, hit, ncp->nc_dvp,
1243 nc_get_name(ncp), vp);
1244 dvp = *vp;
1245 *vp = ncp->nc_dvp;
1246 vref(*vp);
1247 CACHE_RUNLOCK();
1248 vrele(dvp);
1249 CACHE_RLOCK();
1250 return (0);
1251 }
1252 SDT_PROBE1(vfs, namecache, fullpath, miss, vp);
1253
1254 CACHE_RUNLOCK();
1255 vn_lock(*vp, LK_SHARED | LK_RETRY);
1256 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen);
1257 vput(*vp);
1258 if (error) {
1259 numfullpathfail2++;
1260 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL);
1261 return (error);
1262 }
1263
1264 *vp = dvp;
1265 CACHE_RLOCK();
1266 if (dvp->v_iflag & VI_DOOMED) {
1267 /* forced unmount */
1268 CACHE_RUNLOCK();
1269 vrele(dvp);
1270 error = ENOENT;
1271 SDT_PROBE3(vfs, namecache, fullpath, return, error, vp, NULL);
1272 return (error);
1273 }
1274 /*
1275 * *vp has its use count incremented still.
1276 */
1277
1278 return (0);
1279 }
1280
1281 /*
1282 * The magic behind kern___getcwd() and vn_fullpath().
1283 */
1284 static int
1285 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
1286 char *buf, char **retbuf, u_int buflen)
1287 {
1288 int error, slash_prefixed;
1289 #ifdef KDTRACE_HOOKS
1290 struct vnode *startvp = vp;
1291 #endif
1292 struct vnode *vp1;
1293
1294 buflen--;
1295 buf[buflen] = '\0';
1296 error = 0;
1297 slash_prefixed = 0;
1298
1299 SDT_PROBE1(vfs, namecache, fullpath, entry, vp);
1300 numfullpathcalls++;
1301 vref(vp);
1302 CACHE_RLOCK();
1303 if (vp->v_type != VDIR) {
1304 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen);
1305 if (error)
1306 return (error);
1307 if (buflen == 0) {
1308 CACHE_RUNLOCK();
1309 vrele(vp);
1310 return (ENOMEM);
1311 }
1312 buf[--buflen] = '/';
1313 slash_prefixed = 1;
1314 }
1315 while (vp != rdir && vp != rootvnode) {
1316 if (vp->v_vflag & VV_ROOT) {
1317 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */
1318 CACHE_RUNLOCK();
1319 vrele(vp);
1320 error = ENOENT;
1321 SDT_PROBE3(vfs, namecache, fullpath, return,
1322 error, vp, NULL);
1323 break;
1324 }
1325 vp1 = vp->v_mount->mnt_vnodecovered;
1326 vref(vp1);
1327 CACHE_RUNLOCK();
1328 vrele(vp);
1329 vp = vp1;
1330 CACHE_RLOCK();
1331 continue;
1332 }
1333 if (vp->v_type != VDIR) {
1334 CACHE_RUNLOCK();
1335 vrele(vp);
1336 numfullpathfail1++;
1337 error = ENOTDIR;
1338 SDT_PROBE3(vfs, namecache, fullpath, return,
1339 error, vp, NULL);
1340 break;
1341 }
1342 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen);
1343 if (error)
1344 break;
1345 if (buflen == 0) {
1346 CACHE_RUNLOCK();
1347 vrele(vp);
1348 error = ENOMEM;
1349 SDT_PROBE3(vfs, namecache, fullpath, return, error,
1350 startvp, NULL);
1351 break;
1352 }
1353 buf[--buflen] = '/';
1354 slash_prefixed = 1;
1355 }
1356 if (error)
1357 return (error);
1358 if (!slash_prefixed) {
1359 if (buflen == 0) {
1360 CACHE_RUNLOCK();
1361 vrele(vp);
1362 numfullpathfail4++;
1363 SDT_PROBE3(vfs, namecache, fullpath, return, ENOMEM,
1364 startvp, NULL);
1365 return (ENOMEM);
1366 }
1367 buf[--buflen] = '/';
1368 }
1369 numfullpathfound++;
1370 CACHE_RUNLOCK();
1371 vrele(vp);
1372
1373 SDT_PROBE3(vfs, namecache, fullpath, return, 0, startvp, buf + buflen);
1374 *retbuf = buf + buflen;
1375 return (0);
1376 }
1377
1378 struct vnode *
1379 vn_dir_dd_ino(struct vnode *vp)
1380 {
1381 struct namecache *ncp;
1382 struct vnode *ddvp;
1383
1384 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino");
1385 CACHE_RLOCK();
1386 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) {
1387 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0)
1388 continue;
1389 ddvp = ncp->nc_dvp;
1390 VI_LOCK(ddvp);
1391 CACHE_RUNLOCK();
1392 if (vget(ddvp, LK_INTERLOCK | LK_SHARED | LK_NOWAIT, curthread))
1393 return (NULL);
1394 return (ddvp);
1395 }
1396 CACHE_RUNLOCK();
1397 return (NULL);
1398 }
1399
1400 int
1401 vn_commname(struct vnode *vp, char *buf, u_int buflen)
1402 {
1403 struct namecache *ncp;
1404 int l;
1405
1406 CACHE_RLOCK();
1407 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst)
1408 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
1409 break;
1410 if (ncp == NULL) {
1411 CACHE_RUNLOCK();
1412 return (ENOENT);
1413 }
1414 l = min(ncp->nc_nlen, buflen - 1);
1415 memcpy(buf, nc_get_name(ncp), l);
1416 CACHE_RUNLOCK();
1417 buf[l] = '\0';
1418 return (0);
1419 }
1420
1421 /* ABI compat shims for old kernel modules. */
1422 #undef cache_enter
1423
1424 void cache_enter(struct vnode *dvp, struct vnode *vp,
1425 struct componentname *cnp);
1426
1427 void
1428 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp)
1429 {
1430
1431 cache_enter_time(dvp, vp, cnp, NULL, NULL);
1432 }
1433
1434 /*
1435 * This function updates path string to vnode's full global path
1436 * and checks the size of the new path string against the pathlen argument.
1437 *
1438 * Requires a locked, referenced vnode and GIANT lock held.
1439 * Vnode is re-locked on success or ENODEV, otherwise unlocked.
1440 *
1441 * If sysctl debug.disablefullpath is set, ENODEV is returned,
1442 * vnode is left locked and path remain untouched.
1443 *
1444 * If vp is a directory, the call to vn_fullpath_global() always succeeds
1445 * because it falls back to the ".." lookup if the namecache lookup fails.
1446 */
1447 int
1448 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path,
1449 u_int pathlen)
1450 {
1451 struct nameidata nd;
1452 struct vnode *vp1;
1453 char *rpath, *fbuf;
1454 int error;
1455
1456 ASSERT_VOP_ELOCKED(vp, __func__);
1457
1458 /* Return ENODEV if sysctl debug.disablefullpath==1 */
1459 if (disablefullpath)
1460 return (ENODEV);
1461
1462 /* Construct global filesystem path from vp. */
1463 VOP_UNLOCK(vp, 0);
1464 error = vn_fullpath_global(td, vp, &rpath, &fbuf);
1465
1466 if (error != 0) {
1467 vrele(vp);
1468 return (error);
1469 }
1470
1471 if (strlen(rpath) >= pathlen) {
1472 vrele(vp);
1473 error = ENAMETOOLONG;
1474 goto out;
1475 }
1476
1477 /*
1478 * Re-lookup the vnode by path to detect a possible rename.
1479 * As a side effect, the vnode is relocked.
1480 * If vnode was renamed, return ENOENT.
1481 */
1482 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1,
1483 UIO_SYSSPACE, path, td);
1484 error = namei(&nd);
1485 if (error != 0) {
1486 vrele(vp);
1487 goto out;
1488 }
1489 NDFREE(&nd, NDF_ONLY_PNBUF);
1490 vp1 = nd.ni_vp;
1491 vrele(vp);
1492 if (vp1 == vp)
1493 strcpy(path, rpath);
1494 else {
1495 vput(vp1);
1496 error = ENOENT;
1497 }
1498
1499 out:
1500 free(fbuf, M_TEMP);
1501 return (error);
1502 }
Cache object: 79cec01fdecca2c41161f04ce22356fa
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