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 cacheing.
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 *
cache_alloc(int len,int ts)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
cache_free(struct namecache * ncp)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 *
nc_get_name(struct namecache * ncp)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
cache_out_ts(struct namecache * ncp,struct timespec * tsp,int * ticksp)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
308
309 static void cache_zap(struct namecache *ncp);
310 static int vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf,
311 u_int *buflen);
312 static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
313 char *buf, char **retbuf, u_int buflen);
314
315 static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries");
316
317 #ifdef DIAGNOSTIC
318 /*
319 * Grab an atomic snapshot of the name cache hash chain lengths
320 */
321 static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL,
322 "hash table stats");
323
324 static int
sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS)325 sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS)
326 {
327 int error;
328 struct nchashhead *ncpp;
329 struct namecache *ncp;
330 int n_nchash;
331 int count;
332
333 n_nchash = nchash + 1; /* nchash is max index, not count */
334 if (!req->oldptr)
335 return SYSCTL_OUT(req, 0, n_nchash * sizeof(int));
336
337 /* Scan hash tables for applicable entries */
338 for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) {
339 CACHE_RLOCK();
340 count = 0;
341 LIST_FOREACH(ncp, ncpp, nc_hash) {
342 count++;
343 }
344 CACHE_RUNLOCK();
345 error = SYSCTL_OUT(req, &count, sizeof(count));
346 if (error)
347 return (error);
348 }
349 return (0);
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
sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS)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
cache_zap(ncp)412 cache_zap(ncp)
413 struct namecache *ncp;
414 {
415 struct vnode *vp;
416
417 rw_assert(&cache_lock, RA_WLOCKED);
418 CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp);
419 #ifdef KDTRACE_HOOKS
420 if (ncp->nc_vp != NULL) {
421 SDT_PROBE(vfs, namecache, zap, done, ncp->nc_dvp,
422 nc_get_name(ncp), ncp->nc_vp, 0, 0);
423 } else {
424 SDT_PROBE(vfs, namecache, zap_negative, done, ncp->nc_dvp,
425 nc_get_name(ncp), 0, 0, 0);
426 }
427 #endif
428 vp = NULL;
429 LIST_REMOVE(ncp, nc_hash);
430 if (ncp->nc_flag & NCF_ISDOTDOT) {
431 if (ncp == ncp->nc_dvp->v_cache_dd)
432 ncp->nc_dvp->v_cache_dd = NULL;
433 } else {
434 LIST_REMOVE(ncp, nc_src);
435 if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) {
436 vp = ncp->nc_dvp;
437 numcachehv--;
438 }
439 }
440 if (ncp->nc_vp) {
441 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst);
442 if (ncp == ncp->nc_vp->v_cache_dd)
443 ncp->nc_vp->v_cache_dd = NULL;
444 } else {
445 TAILQ_REMOVE(&ncneg, ncp, nc_dst);
446 numneg--;
447 }
448 numcache--;
449 cache_free(ncp);
450 if (vp)
451 vdrop(vp);
452 }
453
454 /*
455 * Lookup an entry in the cache
456 *
457 * Lookup is called with dvp pointing to the directory to search,
458 * cnp pointing to the name of the entry being sought. If the lookup
459 * succeeds, the vnode is returned in *vpp, and a status of -1 is
460 * returned. If the lookup determines that the name does not exist
461 * (negative cacheing), a status of ENOENT is returned. If the lookup
462 * fails, a status of zero is returned. If the directory vnode is
463 * recycled out from under us due to a forced unmount, a status of
464 * ENOENT is returned.
465 *
466 * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is
467 * unlocked. If we're looking up . an extra ref is taken, but the lock is
468 * not recursively acquired.
469 */
470
471 int
cache_lookup(dvp,vpp,cnp,tsp,ticksp)472 cache_lookup(dvp, vpp, cnp, tsp, ticksp)
473 struct vnode *dvp;
474 struct vnode **vpp;
475 struct componentname *cnp;
476 struct timespec *tsp;
477 int *ticksp;
478 {
479 struct namecache *ncp;
480 uint32_t hash;
481 int error, ltype, wlocked;
482
483 if (!doingcache) {
484 cnp->cn_flags &= ~MAKEENTRY;
485 return (0);
486 }
487 retry:
488 CACHE_RLOCK();
489 wlocked = 0;
490 numcalls++;
491 error = 0;
492
493 retry_wlocked:
494 if (cnp->cn_nameptr[0] == '.') {
495 if (cnp->cn_namelen == 1) {
496 *vpp = dvp;
497 CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .",
498 dvp, cnp->cn_nameptr);
499 dothits++;
500 SDT_PROBE(vfs, namecache, lookup, hit, dvp, ".",
501 *vpp, 0, 0);
502 if (tsp != NULL)
503 timespecclear(tsp);
504 if (ticksp != NULL)
505 *ticksp = ticks;
506 goto success;
507 }
508 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
509 dotdothits++;
510 if (dvp->v_cache_dd == NULL) {
511 SDT_PROBE(vfs, namecache, lookup, miss, dvp,
512 "..", NULL, 0, 0);
513 goto unlock;
514 }
515 if ((cnp->cn_flags & MAKEENTRY) == 0) {
516 if (!wlocked && !CACHE_UPGRADE_LOCK())
517 goto wlock;
518 if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT)
519 cache_zap(dvp->v_cache_dd);
520 dvp->v_cache_dd = NULL;
521 CACHE_WUNLOCK();
522 return (0);
523 }
524 ncp = dvp->v_cache_dd;
525 if (ncp->nc_flag & NCF_ISDOTDOT)
526 *vpp = ncp->nc_vp;
527 else
528 *vpp = ncp->nc_dvp;
529 /* Return failure if negative entry was found. */
530 if (*vpp == NULL)
531 goto negative_success;
532 CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..",
533 dvp, cnp->cn_nameptr, *vpp);
534 SDT_PROBE(vfs, namecache, lookup, hit, dvp, "..",
535 *vpp, 0, 0);
536 cache_out_ts(ncp, tsp, ticksp);
537 if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) ==
538 NCF_DTS && tsp != NULL)
539 *tsp = ((struct namecache_ts *)ncp)->
540 nc_dotdottime;
541 goto success;
542 }
543 }
544
545 hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT);
546 hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
547 LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) {
548 numchecks++;
549 if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen &&
550 !bcmp(nc_get_name(ncp), cnp->cn_nameptr, ncp->nc_nlen))
551 break;
552 }
553
554 /* We failed to find an entry */
555 if (ncp == NULL) {
556 SDT_PROBE(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr,
557 NULL, 0, 0);
558 if ((cnp->cn_flags & MAKEENTRY) == 0) {
559 nummisszap++;
560 } else {
561 nummiss++;
562 }
563 nchstats.ncs_miss++;
564 goto unlock;
565 }
566
567 /* We don't want to have an entry, so dump it */
568 if ((cnp->cn_flags & MAKEENTRY) == 0) {
569 numposzaps++;
570 nchstats.ncs_badhits++;
571 if (!wlocked && !CACHE_UPGRADE_LOCK())
572 goto wlock;
573 cache_zap(ncp);
574 CACHE_WUNLOCK();
575 return (0);
576 }
577
578 /* We found a "positive" match, return the vnode */
579 if (ncp->nc_vp) {
580 numposhits++;
581 nchstats.ncs_goodhits++;
582 *vpp = ncp->nc_vp;
583 CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p",
584 dvp, cnp->cn_nameptr, *vpp, ncp);
585 SDT_PROBE(vfs, namecache, lookup, hit, dvp, nc_get_name(ncp),
586 *vpp, 0, 0);
587 cache_out_ts(ncp, tsp, ticksp);
588 goto success;
589 }
590
591 negative_success:
592 /* We found a negative match, and want to create it, so purge */
593 if (cnp->cn_nameiop == CREATE) {
594 numnegzaps++;
595 nchstats.ncs_badhits++;
596 if (!wlocked && !CACHE_UPGRADE_LOCK())
597 goto wlock;
598 cache_zap(ncp);
599 CACHE_WUNLOCK();
600 return (0);
601 }
602
603 if (!wlocked && !CACHE_UPGRADE_LOCK())
604 goto wlock;
605 numneghits++;
606 /*
607 * We found a "negative" match, so we shift it to the end of
608 * the "negative" cache entries queue to satisfy LRU. Also,
609 * check to see if the entry is a whiteout; indicate this to
610 * the componentname, if so.
611 */
612 TAILQ_REMOVE(&ncneg, ncp, nc_dst);
613 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
614 nchstats.ncs_neghits++;
615 if (ncp->nc_flag & NCF_WHITE)
616 cnp->cn_flags |= ISWHITEOUT;
617 SDT_PROBE(vfs, namecache, lookup, hit__negative, dvp, nc_get_name(ncp),
618 0, 0, 0);
619 cache_out_ts(ncp, tsp, ticksp);
620 CACHE_WUNLOCK();
621 return (ENOENT);
622
623 wlock:
624 /*
625 * We need to update the cache after our lookup, so upgrade to
626 * a write lock and retry the operation.
627 */
628 CACHE_RUNLOCK();
629 CACHE_WLOCK();
630 numupgrades++;
631 wlocked = 1;
632 goto retry_wlocked;
633
634 success:
635 /*
636 * On success we return a locked and ref'd vnode as per the lookup
637 * protocol.
638 */
639 if (dvp == *vpp) { /* lookup on "." */
640 VREF(*vpp);
641 if (wlocked)
642 CACHE_WUNLOCK();
643 else
644 CACHE_RUNLOCK();
645 /*
646 * When we lookup "." we still can be asked to lock it
647 * differently...
648 */
649 ltype = cnp->cn_lkflags & LK_TYPE_MASK;
650 if (ltype != VOP_ISLOCKED(*vpp)) {
651 if (ltype == LK_EXCLUSIVE) {
652 vn_lock(*vpp, LK_UPGRADE | LK_RETRY);
653 if ((*vpp)->v_iflag & VI_DOOMED) {
654 /* forced unmount */
655 vrele(*vpp);
656 *vpp = NULL;
657 return (ENOENT);
658 }
659 } else
660 vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY);
661 }
662 return (-1);
663 }
664 ltype = 0; /* silence gcc warning */
665 if (cnp->cn_flags & ISDOTDOT) {
666 ltype = VOP_ISLOCKED(dvp);
667 VOP_UNLOCK(dvp, 0);
668 }
669 VI_LOCK(*vpp);
670 if (wlocked)
671 CACHE_WUNLOCK();
672 else
673 CACHE_RUNLOCK();
674 error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread);
675 if (cnp->cn_flags & ISDOTDOT) {
676 vn_lock(dvp, ltype | LK_RETRY);
677 if (dvp->v_iflag & VI_DOOMED) {
678 if (error == 0)
679 vput(*vpp);
680 *vpp = NULL;
681 return (ENOENT);
682 }
683 }
684 if (error) {
685 *vpp = NULL;
686 goto retry;
687 }
688 if ((cnp->cn_flags & ISLASTCN) &&
689 (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) {
690 ASSERT_VOP_ELOCKED(*vpp, "cache_lookup");
691 }
692 return (-1);
693
694 unlock:
695 if (wlocked)
696 CACHE_WUNLOCK();
697 else
698 CACHE_RUNLOCK();
699 return (0);
700 }
701
702 /*
703 * Add an entry to the cache.
704 */
705 void
cache_enter_time(dvp,vp,cnp,tsp,dtsp)706 cache_enter_time(dvp, vp, cnp, tsp, dtsp)
707 struct vnode *dvp;
708 struct vnode *vp;
709 struct componentname *cnp;
710 struct timespec *tsp;
711 struct timespec *dtsp;
712 {
713 struct namecache *ncp, *n2;
714 struct namecache_ts *n3;
715 struct nchashhead *ncpp;
716 uint32_t hash;
717 int flag;
718 int hold;
719 int zap;
720 int len;
721
722 CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr);
723 VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp,
724 ("cache_enter: Adding a doomed vnode"));
725 VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp,
726 ("cache_enter: Doomed vnode used as src"));
727
728 if (!doingcache)
729 return;
730
731 /*
732 * Avoid blowout in namecache entries.
733 */
734 if (numcache >= desiredvnodes * ncsizefactor)
735 return;
736
737 flag = 0;
738 if (cnp->cn_nameptr[0] == '.') {
739 if (cnp->cn_namelen == 1)
740 return;
741 if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') {
742 CACHE_WLOCK();
743 /*
744 * If dotdot entry already exists, just retarget it
745 * to new parent vnode, otherwise continue with new
746 * namecache entry allocation.
747 */
748 if ((ncp = dvp->v_cache_dd) != NULL &&
749 ncp->nc_flag & NCF_ISDOTDOT) {
750 KASSERT(ncp->nc_dvp == dvp,
751 ("wrong isdotdot parent"));
752 if (ncp->nc_vp != NULL) {
753 TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst,
754 ncp, nc_dst);
755 } else {
756 TAILQ_REMOVE(&ncneg, ncp, nc_dst);
757 numneg--;
758 }
759 if (vp != NULL) {
760 TAILQ_INSERT_HEAD(&vp->v_cache_dst,
761 ncp, nc_dst);
762 } else {
763 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
764 numneg++;
765 }
766 ncp->nc_vp = vp;
767 CACHE_WUNLOCK();
768 return;
769 }
770 dvp->v_cache_dd = NULL;
771 SDT_PROBE(vfs, namecache, enter, done, dvp, "..", vp,
772 0, 0);
773 CACHE_WUNLOCK();
774 flag = NCF_ISDOTDOT;
775 }
776 }
777
778 hold = 0;
779 zap = 0;
780
781 /*
782 * Calculate the hash key and setup as much of the new
783 * namecache entry as possible before acquiring the lock.
784 */
785 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL);
786 ncp->nc_vp = vp;
787 ncp->nc_dvp = dvp;
788 ncp->nc_flag = flag;
789 if (tsp != NULL) {
790 n3 = (struct namecache_ts *)ncp;
791 n3->nc_time = *tsp;
792 n3->nc_ticks = ticks;
793 n3->nc_flag |= NCF_TS;
794 if (dtsp != NULL) {
795 n3->nc_dotdottime = *dtsp;
796 n3->nc_flag |= NCF_DTS;
797 }
798 }
799 len = ncp->nc_nlen = cnp->cn_namelen;
800 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT);
801 strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1);
802 hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
803 CACHE_WLOCK();
804
805 /*
806 * See if this vnode or negative entry is already in the cache
807 * with this name. This can happen with concurrent lookups of
808 * the same path name.
809 */
810 ncpp = NCHHASH(hash);
811 LIST_FOREACH(n2, ncpp, nc_hash) {
812 if (n2->nc_dvp == dvp &&
813 n2->nc_nlen == cnp->cn_namelen &&
814 !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) {
815 if (tsp != NULL) {
816 KASSERT((n2->nc_flag & NCF_TS) != 0,
817 ("no NCF_TS"));
818 n3 = (struct namecache_ts *)n2;
819 n3->nc_time =
820 ((struct namecache_ts *)ncp)->nc_time;
821 n3->nc_ticks =
822 ((struct namecache_ts *)ncp)->nc_ticks;
823 if (dtsp != NULL) {
824 n3->nc_dotdottime =
825 ((struct namecache_ts *)ncp)->
826 nc_dotdottime;
827 n3->nc_flag |= NCF_DTS;
828 }
829 }
830 CACHE_WUNLOCK();
831 cache_free(ncp);
832 return;
833 }
834 }
835
836 if (flag == NCF_ISDOTDOT) {
837 /*
838 * See if we are trying to add .. entry, but some other lookup
839 * has populated v_cache_dd pointer already.
840 */
841 if (dvp->v_cache_dd != NULL) {
842 CACHE_WUNLOCK();
843 cache_free(ncp);
844 return;
845 }
846 KASSERT(vp == NULL || vp->v_type == VDIR,
847 ("wrong vnode type %p", vp));
848 dvp->v_cache_dd = ncp;
849 }
850
851 numcache++;
852 if (!vp) {
853 numneg++;
854 if (cnp->cn_flags & ISWHITEOUT)
855 ncp->nc_flag |= NCF_WHITE;
856 } else if (vp->v_type == VDIR) {
857 if (flag != NCF_ISDOTDOT) {
858 /*
859 * For this case, the cache entry maps both the
860 * directory name in it and the name ".." for the
861 * directory's parent.
862 */
863 if ((n2 = vp->v_cache_dd) != NULL &&
864 (n2->nc_flag & NCF_ISDOTDOT) != 0)
865 cache_zap(n2);
866 vp->v_cache_dd = ncp;
867 }
868 } else {
869 vp->v_cache_dd = NULL;
870 }
871
872 /*
873 * Insert the new namecache entry into the appropriate chain
874 * within the cache entries table.
875 */
876 LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
877 if (flag != NCF_ISDOTDOT) {
878 if (LIST_EMPTY(&dvp->v_cache_src)) {
879 hold = 1;
880 numcachehv++;
881 }
882 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src);
883 }
884
885 /*
886 * If the entry is "negative", we place it into the
887 * "negative" cache queue, otherwise, we place it into the
888 * destination vnode's cache entries queue.
889 */
890 if (vp) {
891 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst);
892 SDT_PROBE(vfs, namecache, enter, done, dvp, nc_get_name(ncp),
893 vp, 0, 0);
894 } else {
895 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
896 SDT_PROBE(vfs, namecache, enter_negative, done, dvp,
897 nc_get_name(ncp), 0, 0, 0);
898 }
899 if (numneg * ncnegfactor > numcache) {
900 ncp = TAILQ_FIRST(&ncneg);
901 KASSERT(ncp->nc_vp == NULL, ("ncp %p vp %p on ncneg",
902 ncp, ncp->nc_vp));
903 zap = 1;
904 }
905 if (hold)
906 vhold(dvp);
907 if (zap)
908 cache_zap(ncp);
909 CACHE_WUNLOCK();
910 }
911
912 /*
913 * Name cache initialization, from vfs_init() when we are booting
914 */
915 static void
nchinit(void * dummy __unused)916 nchinit(void *dummy __unused)
917 {
918
919 TAILQ_INIT(&ncneg);
920
921 cache_zone_small = uma_zcreate("S VFS Cache",
922 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1,
923 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
924 cache_zone_small_ts = uma_zcreate("STS VFS Cache",
925 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1,
926 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
927 cache_zone_large = uma_zcreate("L VFS Cache",
928 sizeof(struct namecache) + NAME_MAX + 1,
929 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
930 cache_zone_large_ts = uma_zcreate("LTS VFS Cache",
931 sizeof(struct namecache_ts) + NAME_MAX + 1,
932 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
933
934 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash);
935 }
936 SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
937
938
939 /*
940 * Invalidate all entries to a particular vnode.
941 */
942 void
cache_purge(vp)943 cache_purge(vp)
944 struct vnode *vp;
945 {
946
947 CTR1(KTR_VFS, "cache_purge(%p)", vp);
948 SDT_PROBE(vfs, namecache, purge, done, vp, 0, 0, 0, 0);
949 CACHE_WLOCK();
950 while (!LIST_EMPTY(&vp->v_cache_src))
951 cache_zap(LIST_FIRST(&vp->v_cache_src));
952 while (!TAILQ_EMPTY(&vp->v_cache_dst))
953 cache_zap(TAILQ_FIRST(&vp->v_cache_dst));
954 if (vp->v_cache_dd != NULL) {
955 KASSERT(vp->v_cache_dd->nc_flag & NCF_ISDOTDOT,
956 ("lost dotdot link"));
957 cache_zap(vp->v_cache_dd);
958 }
959 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge"));
960 CACHE_WUNLOCK();
961 }
962
963 /*
964 * Invalidate all negative entries for a particular directory vnode.
965 */
966 void
cache_purge_negative(vp)967 cache_purge_negative(vp)
968 struct vnode *vp;
969 {
970 struct namecache *cp, *ncp;
971
972 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp);
973 SDT_PROBE(vfs, namecache, purge_negative, done, vp, 0, 0, 0, 0);
974 CACHE_WLOCK();
975 LIST_FOREACH_SAFE(cp, &vp->v_cache_src, nc_src, ncp) {
976 if (cp->nc_vp == NULL)
977 cache_zap(cp);
978 }
979 CACHE_WUNLOCK();
980 }
981
982 /*
983 * Flush all entries referencing a particular filesystem.
984 */
985 void
cache_purgevfs(mp)986 cache_purgevfs(mp)
987 struct mount *mp;
988 {
989 struct nchashhead *ncpp;
990 struct namecache *ncp, *nnp;
991
992 /* Scan hash tables for applicable entries */
993 SDT_PROBE(vfs, namecache, purgevfs, done, mp, 0, 0, 0, 0);
994 CACHE_WLOCK();
995 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) {
996 LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) {
997 if (ncp->nc_dvp->v_mount == mp)
998 cache_zap(ncp);
999 }
1000 }
1001 CACHE_WUNLOCK();
1002 }
1003
1004 /*
1005 * Perform canonical checks and cache lookup and pass on to filesystem
1006 * through the vop_cachedlookup only if needed.
1007 */
1008
1009 int
vfs_cache_lookup(ap)1010 vfs_cache_lookup(ap)
1011 struct vop_lookup_args /* {
1012 struct vnode *a_dvp;
1013 struct vnode **a_vpp;
1014 struct componentname *a_cnp;
1015 } */ *ap;
1016 {
1017 struct vnode *dvp;
1018 int error;
1019 struct vnode **vpp = ap->a_vpp;
1020 struct componentname *cnp = ap->a_cnp;
1021 struct ucred *cred = cnp->cn_cred;
1022 int flags = cnp->cn_flags;
1023 struct thread *td = cnp->cn_thread;
1024
1025 *vpp = NULL;
1026 dvp = ap->a_dvp;
1027
1028 if (dvp->v_type != VDIR)
1029 return (ENOTDIR);
1030
1031 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
1032 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
1033 return (EROFS);
1034
1035 error = VOP_ACCESS(dvp, VEXEC, cred, td);
1036 if (error)
1037 return (error);
1038
1039 error = cache_lookup(dvp, vpp, cnp, NULL, NULL);
1040 if (error == 0)
1041 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
1042 if (error == -1)
1043 return (0);
1044 return (error);
1045 }
1046
1047 /*
1048 * XXX All of these sysctls would probably be more productive dead.
1049 */
1050 static int disablecwd;
1051 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0,
1052 "Disable the getcwd syscall");
1053
1054 /* Implementation of the getcwd syscall. */
1055 int
sys___getcwd(td,uap)1056 sys___getcwd(td, uap)
1057 struct thread *td;
1058 struct __getcwd_args *uap;
1059 {
1060
1061 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen));
1062 }
1063
1064 int
kern___getcwd(struct thread * td,char * buf,enum uio_seg bufseg,u_int buflen)1065 kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, u_int buflen)
1066 {
1067 char *bp, *tmpbuf;
1068 struct filedesc *fdp;
1069 struct vnode *cdir, *rdir;
1070 int error;
1071
1072 if (disablecwd)
1073 return (ENODEV);
1074 if (buflen < 2)
1075 return (EINVAL);
1076 if (buflen > MAXPATHLEN)
1077 buflen = MAXPATHLEN;
1078
1079 tmpbuf = malloc(buflen, M_TEMP, M_WAITOK);
1080 fdp = td->td_proc->p_fd;
1081 FILEDESC_SLOCK(fdp);
1082 cdir = fdp->fd_cdir;
1083 VREF(cdir);
1084 rdir = fdp->fd_rdir;
1085 VREF(rdir);
1086 FILEDESC_SUNLOCK(fdp);
1087 error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen);
1088 vrele(rdir);
1089 vrele(cdir);
1090
1091 if (!error) {
1092 if (bufseg == UIO_SYSSPACE)
1093 bcopy(bp, buf, strlen(bp) + 1);
1094 else
1095 error = copyout(bp, buf, strlen(bp) + 1);
1096 #ifdef KTRACE
1097 if (KTRPOINT(curthread, KTR_NAMEI))
1098 ktrnamei(bp);
1099 #endif
1100 }
1101 free(tmpbuf, M_TEMP);
1102 return (error);
1103 }
1104
1105 /*
1106 * Thus begins the fullpath magic.
1107 */
1108
1109 #undef STATNODE
1110 #define STATNODE(name, descr) \
1111 static u_int name; \
1112 SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr)
1113
1114 static int disablefullpath;
1115 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0,
1116 "Disable the vn_fullpath function");
1117
1118 /* These count for kern___getcwd(), too. */
1119 STATNODE(numfullpathcalls, "Number of fullpath search calls");
1120 STATNODE(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)");
1121 STATNODE(numfullpathfail2,
1122 "Number of fullpath search errors (VOP_VPTOCNP failures)");
1123 STATNODE(numfullpathfail4, "Number of fullpath search errors (ENOMEM)");
1124 STATNODE(numfullpathfound, "Number of successful fullpath calls");
1125
1126 /*
1127 * Retrieve the full filesystem path that correspond to a vnode from the name
1128 * cache (if available)
1129 */
1130 int
vn_fullpath(struct thread * td,struct vnode * vn,char ** retbuf,char ** freebuf)1131 vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf)
1132 {
1133 char *buf;
1134 struct filedesc *fdp;
1135 struct vnode *rdir;
1136 int error;
1137
1138 if (disablefullpath)
1139 return (ENODEV);
1140 if (vn == NULL)
1141 return (EINVAL);
1142
1143 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1144 fdp = td->td_proc->p_fd;
1145 FILEDESC_SLOCK(fdp);
1146 rdir = fdp->fd_rdir;
1147 VREF(rdir);
1148 FILEDESC_SUNLOCK(fdp);
1149 error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN);
1150 vrele(rdir);
1151
1152 if (!error)
1153 *freebuf = buf;
1154 else
1155 free(buf, M_TEMP);
1156 return (error);
1157 }
1158
1159 /*
1160 * This function is similar to vn_fullpath, but it attempts to lookup the
1161 * pathname relative to the global root mount point. This is required for the
1162 * auditing sub-system, as audited pathnames must be absolute, relative to the
1163 * global root mount point.
1164 */
1165 int
vn_fullpath_global(struct thread * td,struct vnode * vn,char ** retbuf,char ** freebuf)1166 vn_fullpath_global(struct thread *td, struct vnode *vn,
1167 char **retbuf, char **freebuf)
1168 {
1169 char *buf;
1170 int error;
1171
1172 if (disablefullpath)
1173 return (ENODEV);
1174 if (vn == NULL)
1175 return (EINVAL);
1176 buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
1177 error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN);
1178 if (!error)
1179 *freebuf = buf;
1180 else
1181 free(buf, M_TEMP);
1182 return (error);
1183 }
1184
1185 int
vn_vptocnp(struct vnode ** vp,struct ucred * cred,char * buf,u_int * buflen)1186 vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen)
1187 {
1188 int error;
1189
1190 CACHE_RLOCK();
1191 error = vn_vptocnp_locked(vp, cred, buf, buflen);
1192 if (error == 0)
1193 CACHE_RUNLOCK();
1194 return (error);
1195 }
1196
1197 static int
vn_vptocnp_locked(struct vnode ** vp,struct ucred * cred,char * buf,u_int * buflen)1198 vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf,
1199 u_int *buflen)
1200 {
1201 struct vnode *dvp;
1202 struct namecache *ncp;
1203 int error;
1204
1205 TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) {
1206 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
1207 break;
1208 }
1209 if (ncp != NULL) {
1210 if (*buflen < ncp->nc_nlen) {
1211 CACHE_RUNLOCK();
1212 vrele(*vp);
1213 numfullpathfail4++;
1214 error = ENOMEM;
1215 SDT_PROBE(vfs, namecache, fullpath, return, error,
1216 vp, NULL, 0, 0);
1217 return (error);
1218 }
1219 *buflen -= ncp->nc_nlen;
1220 memcpy(buf + *buflen, nc_get_name(ncp), ncp->nc_nlen);
1221 SDT_PROBE(vfs, namecache, fullpath, hit, ncp->nc_dvp,
1222 nc_get_name(ncp), vp, 0, 0);
1223 dvp = *vp;
1224 *vp = ncp->nc_dvp;
1225 vref(*vp);
1226 CACHE_RUNLOCK();
1227 vrele(dvp);
1228 CACHE_RLOCK();
1229 return (0);
1230 }
1231 SDT_PROBE(vfs, namecache, fullpath, miss, vp, 0, 0, 0, 0);
1232
1233 CACHE_RUNLOCK();
1234 vn_lock(*vp, LK_SHARED | LK_RETRY);
1235 error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen);
1236 vput(*vp);
1237 if (error) {
1238 numfullpathfail2++;
1239 SDT_PROBE(vfs, namecache, fullpath, return, error, vp,
1240 NULL, 0, 0);
1241 return (error);
1242 }
1243
1244 *vp = dvp;
1245 CACHE_RLOCK();
1246 if (dvp->v_iflag & VI_DOOMED) {
1247 /* forced unmount */
1248 CACHE_RUNLOCK();
1249 vrele(dvp);
1250 error = ENOENT;
1251 SDT_PROBE(vfs, namecache, fullpath, return, error, vp,
1252 NULL, 0, 0);
1253 return (error);
1254 }
1255 /*
1256 * *vp has its use count incremented still.
1257 */
1258
1259 return (0);
1260 }
1261
1262 /*
1263 * The magic behind kern___getcwd() and vn_fullpath().
1264 */
1265 static int
vn_fullpath1(struct thread * td,struct vnode * vp,struct vnode * rdir,char * buf,char ** retbuf,u_int buflen)1266 vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
1267 char *buf, char **retbuf, u_int buflen)
1268 {
1269 int error, slash_prefixed;
1270 #ifdef KDTRACE_HOOKS
1271 struct vnode *startvp = vp;
1272 #endif
1273 struct vnode *vp1;
1274
1275 buflen--;
1276 buf[buflen] = '\0';
1277 error = 0;
1278 slash_prefixed = 0;
1279
1280 SDT_PROBE(vfs, namecache, fullpath, entry, vp, 0, 0, 0, 0);
1281 numfullpathcalls++;
1282 vref(vp);
1283 CACHE_RLOCK();
1284 if (vp->v_type != VDIR) {
1285 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen);
1286 if (error)
1287 return (error);
1288 if (buflen == 0) {
1289 CACHE_RUNLOCK();
1290 vrele(vp);
1291 return (ENOMEM);
1292 }
1293 buf[--buflen] = '/';
1294 slash_prefixed = 1;
1295 }
1296 while (vp != rdir && vp != rootvnode) {
1297 if (vp->v_vflag & VV_ROOT) {
1298 if (vp->v_iflag & VI_DOOMED) { /* forced unmount */
1299 CACHE_RUNLOCK();
1300 vrele(vp);
1301 error = ENOENT;
1302 SDT_PROBE(vfs, namecache, fullpath, return,
1303 error, vp, NULL, 0, 0);
1304 break;
1305 }
1306 vp1 = vp->v_mount->mnt_vnodecovered;
1307 vref(vp1);
1308 CACHE_RUNLOCK();
1309 vrele(vp);
1310 vp = vp1;
1311 CACHE_RLOCK();
1312 continue;
1313 }
1314 if (vp->v_type != VDIR) {
1315 CACHE_RUNLOCK();
1316 vrele(vp);
1317 numfullpathfail1++;
1318 error = ENOTDIR;
1319 SDT_PROBE(vfs, namecache, fullpath, return,
1320 error, vp, NULL, 0, 0);
1321 break;
1322 }
1323 error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen);
1324 if (error)
1325 break;
1326 if (buflen == 0) {
1327 CACHE_RUNLOCK();
1328 vrele(vp);
1329 error = ENOMEM;
1330 SDT_PROBE(vfs, namecache, fullpath, return, error,
1331 startvp, NULL, 0, 0);
1332 break;
1333 }
1334 buf[--buflen] = '/';
1335 slash_prefixed = 1;
1336 }
1337 if (error)
1338 return (error);
1339 if (!slash_prefixed) {
1340 if (buflen == 0) {
1341 CACHE_RUNLOCK();
1342 vrele(vp);
1343 numfullpathfail4++;
1344 SDT_PROBE(vfs, namecache, fullpath, return, ENOMEM,
1345 startvp, NULL, 0, 0);
1346 return (ENOMEM);
1347 }
1348 buf[--buflen] = '/';
1349 }
1350 numfullpathfound++;
1351 CACHE_RUNLOCK();
1352 vrele(vp);
1353
1354 SDT_PROBE(vfs, namecache, fullpath, return, 0, startvp, buf + buflen,
1355 0, 0);
1356 *retbuf = buf + buflen;
1357 return (0);
1358 }
1359
1360 struct vnode *
vn_dir_dd_ino(struct vnode * vp)1361 vn_dir_dd_ino(struct vnode *vp)
1362 {
1363 struct namecache *ncp;
1364 struct vnode *ddvp;
1365
1366 ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino");
1367 CACHE_RLOCK();
1368 TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) {
1369 if ((ncp->nc_flag & NCF_ISDOTDOT) != 0)
1370 continue;
1371 ddvp = ncp->nc_dvp;
1372 VI_LOCK(ddvp);
1373 CACHE_RUNLOCK();
1374 if (vget(ddvp, LK_INTERLOCK | LK_SHARED | LK_NOWAIT, curthread))
1375 return (NULL);
1376 return (ddvp);
1377 }
1378 CACHE_RUNLOCK();
1379 return (NULL);
1380 }
1381
1382 int
vn_commname(struct vnode * vp,char * buf,u_int buflen)1383 vn_commname(struct vnode *vp, char *buf, u_int buflen)
1384 {
1385 struct namecache *ncp;
1386 int l;
1387
1388 CACHE_RLOCK();
1389 TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst)
1390 if ((ncp->nc_flag & NCF_ISDOTDOT) == 0)
1391 break;
1392 if (ncp == NULL) {
1393 CACHE_RUNLOCK();
1394 return (ENOENT);
1395 }
1396 l = min(ncp->nc_nlen, buflen - 1);
1397 memcpy(buf, nc_get_name(ncp), l);
1398 CACHE_RUNLOCK();
1399 buf[l] = '\0';
1400 return (0);
1401 }
1402
1403 /* ABI compat shims for old kernel modules. */
1404 #undef cache_enter
1405
1406 void cache_enter(struct vnode *dvp, struct vnode *vp,
1407 struct componentname *cnp);
1408
1409 void
cache_enter(struct vnode * dvp,struct vnode * vp,struct componentname * cnp)1410 cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp)
1411 {
1412
1413 cache_enter_time(dvp, vp, cnp, NULL, NULL);
1414 }
1415
1416 /*
1417 * This function updates path string to vnode's full global path
1418 * and checks the size of the new path string against the pathlen argument.
1419 *
1420 * Requires a locked, referenced vnode and GIANT lock held.
1421 * Vnode is re-locked on success or ENODEV, otherwise unlocked.
1422 *
1423 * If sysctl debug.disablefullpath is set, ENODEV is returned,
1424 * vnode is left locked and path remain untouched.
1425 *
1426 * If vp is a directory, the call to vn_fullpath_global() always succeeds
1427 * because it falls back to the ".." lookup if the namecache lookup fails.
1428 */
1429 int
vn_path_to_global_path(struct thread * td,struct vnode * vp,char * path,u_int pathlen)1430 vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path,
1431 u_int pathlen)
1432 {
1433 struct nameidata nd;
1434 struct vnode *vp1;
1435 char *rpath, *fbuf;
1436 int error;
1437
1438 ASSERT_VOP_ELOCKED(vp, __func__);
1439
1440 /* Return ENODEV if sysctl debug.disablefullpath==1 */
1441 if (disablefullpath)
1442 return (ENODEV);
1443
1444 /* Construct global filesystem path from vp. */
1445 VOP_UNLOCK(vp, 0);
1446 error = vn_fullpath_global(td, vp, &rpath, &fbuf);
1447
1448 if (error != 0) {
1449 vrele(vp);
1450 return (error);
1451 }
1452
1453 if (strlen(rpath) >= pathlen) {
1454 vrele(vp);
1455 error = ENAMETOOLONG;
1456 goto out;
1457 }
1458
1459 /*
1460 * Re-lookup the vnode by path to detect a possible rename.
1461 * As a side effect, the vnode is relocked.
1462 * If vnode was renamed, return ENOENT.
1463 */
1464 NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1,
1465 UIO_SYSSPACE, path, td);
1466 error = namei(&nd);
1467 if (error != 0) {
1468 vrele(vp);
1469 goto out;
1470 }
1471 NDFREE(&nd, NDF_ONLY_PNBUF);
1472 vp1 = nd.ni_vp;
1473 vrele(vp);
1474 if (vp1 == vp)
1475 strcpy(path, rpath);
1476 else {
1477 vput(vp1);
1478 error = ENOENT;
1479 }
1480
1481 out:
1482 free(fbuf, M_TEMP);
1483 return (error);
1484 }
1485