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
64SDT_PROVIDER_DECLARE(vfs);
65SDT_PROBE_DEFINE3(vfs, namecache, enter, done, done, "struct vnode *", "char *",
66 "struct vnode *");
67SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, done, "struct vnode *",
68 "char *");
69SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, entry, "struct vnode *");
70SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, hit, "struct vnode *",
71 "struct char *", "struct vnode *");
72SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, miss, "struct vnode *");
73SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, return, "int",
74 "struct vnode *", "struct char *");
75SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, hit, "struct vnode *", "char *",
76 "struct vnode *");
77SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit_negative, hit-negative,
78 "struct vnode *", "char *");
79SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, miss, "struct vnode *",
80 "char *");
81SDT_PROBE_DEFINE1(vfs, namecache, purge, done, done, "struct vnode *");
82SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, done, "struct vnode *");
83SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, done, "struct mount *");
84SDT_PROBE_DEFINE3(vfs, namecache, zap, done, done, "struct vnode *", "char *",
85 "struct vnode *");
86SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, 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
94struct 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 */
113struct 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])
157static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */
158static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */
159static u_long nchash; /* size of hash table */
160SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0,
161 "Size of namecache hash table");
162static u_long ncnegfactor = 16; /* ratio of negative entries */
163SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0,
164 "Ratio of negative namecache entries");
165static u_long numneg; /* number of negative entries allocated */
166SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0,
167 "Number of negative entries in namecache");
168static u_long numcache; /* number of cache entries allocated */
169SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0,
170 "Number of namecache entries");
171static u_long numcachehv; /* number of cache entries with vnodes held */
172SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0,
173 "Number of namecache entries with vnodes held");
174static u_int ncsizefactor = 2;
175SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0,
176 "Size factor for namecache");
177
178struct nchstats nchstats; /* cache effectiveness statistics */
179
180static struct rwlock cache_lock;
181RW_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 */
196static uma_zone_t cache_zone_small;
197static uma_zone_t cache_zone_small_ts;
198static uma_zone_t cache_zone_large;
199static uma_zone_t cache_zone_large_ts;
200
201#define CACHE_PATH_CUTOFF 35
202
203static struct namecache *
204cache_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
219static void
220cache_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
238static char *
239nc_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
249static void
250cache_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
263static int doingcache = 1; /* 1 => enable the cache */
264SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0,
265 "VFS namecache enabled");
266
267/* Export size information to userland */
268SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, 0,
269 sizeof(struct namecache), "sizeof(struct namecache)");
270
271/*
272 * The new name cache statistics
273 */
274static 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);
278STATNODE(CTLFLAG_RD, numneg, &numneg, "Number of negative cache entries");
279STATNODE(CTLFLAG_RD, numcache, &numcache, "Number of cache entries");
280static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls,
281 "Number of cache lookups");
282static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits,
283 "Number of '.' hits");
284static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits,
285 "Number of '..' hits");
286static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks,
287 "Number of checks in lookup");
288static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss,
289 "Number of cache misses");
290static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap,
291 "Number of cache misses we do not want to cache");
292static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps,
293 "Number of cache hits (positive) we do not want to cache");
294static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits,
295 "Number of cache hits (positive)");
296static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps,
297 "Number of cache hits (negative) we do not want to cache");
298static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits,
299 "Number of cache hits (negative)");
300static u_long numupgrades; STATNODE(CTLFLAG_RD, numupgrades, &numupgrades,
301 "Number of updates of the cache after lookup (write lock + retry)");
302
303SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD | CTLFLAG_MPSAFE,
304 &nchstats, sizeof(nchstats), "LU",
305 "VFS cache effectiveness statistics");
306
307
308
309static void cache_zap(struct namecache *ncp);
310static int vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf,
311 u_int *buflen);
312static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
313 char *buf, char **retbuf, u_int buflen);
314
315static 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 */
321static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL,
322 "hash table stats");
323
324static int
325sysctl_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}
351SYSCTL_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
355static int
356sysctl_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}
400SYSCTL_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 */
411static void
412cache_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
471int
472cache_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 }
487retry:
488 CACHE_RLOCK();
489 wlocked = 0;
490 numcalls++;
491 error = 0;
492
493retry_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
591negative_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
623wlock:
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
634success:
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
694unlock:
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 */
705void
706cache_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 if (vp != NULL)
758 TAILQ_INSERT_HEAD(&vp->v_cache_dst,
759 ncp, nc_dst);
760 else
761 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
762 ncp->nc_vp = vp;
763 CACHE_WUNLOCK();
764 return;
765 }
766 dvp->v_cache_dd = NULL;
767 SDT_PROBE(vfs, namecache, enter, done, dvp, "..", vp,
768 0, 0);
769 CACHE_WUNLOCK();
770 flag = NCF_ISDOTDOT;
771 }
772 }
773
774 hold = 0;
775 zap = 0;
776
777 /*
778 * Calculate the hash key and setup as much of the new
779 * namecache entry as possible before acquiring the lock.
780 */
781 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL);
782 ncp->nc_vp = vp;
783 ncp->nc_dvp = dvp;
784 ncp->nc_flag = flag;
785 if (tsp != NULL) {
786 n3 = (struct namecache_ts *)ncp;
787 n3->nc_time = *tsp;
788 n3->nc_ticks = ticks;
789 n3->nc_flag |= NCF_TS;
790 if (dtsp != NULL) {
791 n3->nc_dotdottime = *dtsp;
792 n3->nc_flag |= NCF_DTS;
793 }
794 }
795 len = ncp->nc_nlen = cnp->cn_namelen;
796 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT);
797 strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1);
798 hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
799 CACHE_WLOCK();
800
801 /*
802 * See if this vnode or negative entry is already in the cache
803 * with this name. This can happen with concurrent lookups of
804 * the same path name.
805 */
806 ncpp = NCHHASH(hash);
807 LIST_FOREACH(n2, ncpp, nc_hash) {
808 if (n2->nc_dvp == dvp &&
809 n2->nc_nlen == cnp->cn_namelen &&
810 !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) {
811 if (tsp != NULL) {
812 KASSERT((n2->nc_flag & NCF_TS) != 0,
813 ("no NCF_TS"));
814 n3 = (struct namecache_ts *)n2;
815 n3->nc_time =
816 ((struct namecache_ts *)ncp)->nc_time;
817 n3->nc_ticks =
818 ((struct namecache_ts *)ncp)->nc_ticks;
819 if (dtsp != NULL) {
820 n3->nc_dotdottime =
821 ((struct namecache_ts *)ncp)->
822 nc_dotdottime;
823 n3->nc_flag |= NCF_DTS;
824 }
825 }
826 CACHE_WUNLOCK();
827 cache_free(ncp);
828 return;
829 }
830 }
831
832 if (flag == NCF_ISDOTDOT) {
833 /*
834 * See if we are trying to add .. entry, but some other lookup
835 * has populated v_cache_dd pointer already.
836 */
837 if (dvp->v_cache_dd != NULL) {
838 CACHE_WUNLOCK();
839 cache_free(ncp);
840 return;
841 }
842 KASSERT(vp == NULL || vp->v_type == VDIR,
843 ("wrong vnode type %p", vp));
844 dvp->v_cache_dd = ncp;
845 }
846
847 numcache++;
848 if (!vp) {
849 numneg++;
850 if (cnp->cn_flags & ISWHITEOUT)
851 ncp->nc_flag |= NCF_WHITE;
852 } else if (vp->v_type == VDIR) {
853 if (flag != NCF_ISDOTDOT) {
854 /*
855 * For this case, the cache entry maps both the
856 * directory name in it and the name ".." for the
857 * directory's parent.
858 */
859 if ((n2 = vp->v_cache_dd) != NULL &&
860 (n2->nc_flag & NCF_ISDOTDOT) != 0)
861 cache_zap(n2);
862 vp->v_cache_dd = ncp;
863 }
864 } else {
865 vp->v_cache_dd = NULL;
866 }
867
868 /*
869 * Insert the new namecache entry into the appropriate chain
870 * within the cache entries table.
871 */
872 LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
873 if (flag != NCF_ISDOTDOT) {
874 if (LIST_EMPTY(&dvp->v_cache_src)) {
875 hold = 1;
876 numcachehv++;
877 }
878 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src);
879 }
880
881 /*
882 * If the entry is "negative", we place it into the
883 * "negative" cache queue, otherwise, we place it into the
884 * destination vnode's cache entries queue.
885 */
886 if (vp) {
887 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst);
888 SDT_PROBE(vfs, namecache, enter, done, dvp, nc_get_name(ncp),
889 vp, 0, 0);
890 } else {
891 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
892 SDT_PROBE(vfs, namecache, enter_negative, done, dvp,
893 nc_get_name(ncp), 0, 0, 0);
894 }
895 if (numneg * ncnegfactor > numcache) {
896 ncp = TAILQ_FIRST(&ncneg);
897 zap = 1;
898 }
899 if (hold)
900 vhold(dvp);
901 if (zap)
902 cache_zap(ncp);
903 CACHE_WUNLOCK();
904}
905
906/*
907 * Name cache initialization, from vfs_init() when we are booting
908 */
909static void
910nchinit(void *dummy __unused)
911{
912
913 TAILQ_INIT(&ncneg);
914
915 cache_zone_small = uma_zcreate("S VFS Cache",
916 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1,
917 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
918 cache_zone_small_ts = uma_zcreate("STS VFS Cache",
919 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1,
920 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
921 cache_zone_large = uma_zcreate("L VFS Cache",
922 sizeof(struct namecache) + NAME_MAX + 1,
923 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
924 cache_zone_large_ts = uma_zcreate("LTS VFS Cache",
925 sizeof(struct namecache_ts) + NAME_MAX + 1,
926 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
927
928 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash);
929}
930SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
931
932
933/*
934 * Invalidate all entries to a particular vnode.
935 */
936void
937cache_purge(vp)
938 struct vnode *vp;
939{
940
941 CTR1(KTR_VFS, "cache_purge(%p)", vp);
942 SDT_PROBE(vfs, namecache, purge, done, vp, 0, 0, 0, 0);
943 CACHE_WLOCK();
944 while (!LIST_EMPTY(&vp->v_cache_src))
945 cache_zap(LIST_FIRST(&vp->v_cache_src));
946 while (!TAILQ_EMPTY(&vp->v_cache_dst))
947 cache_zap(TAILQ_FIRST(&vp->v_cache_dst));
948 if (vp->v_cache_dd != NULL) {
949 KASSERT(vp->v_cache_dd->nc_flag & NCF_ISDOTDOT,
950 ("lost dotdot link"));
951 cache_zap(vp->v_cache_dd);
952 }
953 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge"));
954 CACHE_WUNLOCK();
955}
956
957/*
958 * Invalidate all negative entries for a particular directory vnode.
959 */
960void
961cache_purge_negative(vp)
962 struct vnode *vp;
963{
964 struct namecache *cp, *ncp;
965
966 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp);
967 SDT_PROBE(vfs, namecache, purge_negative, done, vp, 0, 0, 0, 0);
968 CACHE_WLOCK();
969 LIST_FOREACH_SAFE(cp, &vp->v_cache_src, nc_src, ncp) {
970 if (cp->nc_vp == NULL)
971 cache_zap(cp);
972 }
973 CACHE_WUNLOCK();
974}
975
976/*
977 * Flush all entries referencing a particular filesystem.
978 */
979void
980cache_purgevfs(mp)
981 struct mount *mp;
982{
983 struct nchashhead *ncpp;
984 struct namecache *ncp, *nnp;
985
986 /* Scan hash tables for applicable entries */
987 SDT_PROBE(vfs, namecache, purgevfs, done, mp, 0, 0, 0, 0);
988 CACHE_WLOCK();
989 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) {
990 LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) {
991 if (ncp->nc_dvp->v_mount == mp)
992 cache_zap(ncp);
993 }
994 }
995 CACHE_WUNLOCK();
996}
997
998/*
999 * Perform canonical checks and cache lookup and pass on to filesystem
1000 * through the vop_cachedlookup only if needed.
1001 */
1002
1003int
1004vfs_cache_lookup(ap)
1005 struct vop_lookup_args /* {
1006 struct vnode *a_dvp;
1007 struct vnode **a_vpp;
1008 struct componentname *a_cnp;
1009 } */ *ap;
1010{
1011 struct vnode *dvp;
1012 int error;
1013 struct vnode **vpp = ap->a_vpp;
1014 struct componentname *cnp = ap->a_cnp;
1015 struct ucred *cred = cnp->cn_cred;
1016 int flags = cnp->cn_flags;
1017 struct thread *td = cnp->cn_thread;
1018
1019 *vpp = NULL;
1020 dvp = ap->a_dvp;
1021
1022 if (dvp->v_type != VDIR)
1023 return (ENOTDIR);
1024
1025 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
1026 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
1027 return (EROFS);
1028
1029 error = VOP_ACCESS(dvp, VEXEC, cred, td);
1030 if (error)
1031 return (error);
1032
1033 error = cache_lookup(dvp, vpp, cnp, NULL, NULL);
1034 if (error == 0)
1035 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
1036 if (error == -1)
1037 return (0);
1038 return (error);
1039}
1040
1041
1042#ifndef _SYS_SYSPROTO_H_
1043struct __getcwd_args {
1044 u_char *buf;
1045 u_int buflen;
1046};
1047#endif
1048
1049/*
1050 * XXX All of these sysctls would probably be more productive dead.
1051 */
1052static int disablecwd;
1053SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0,
1054 "Disable the getcwd syscall");
1055
1056/* Implementation of the getcwd syscall. */
1057int
1058sys___getcwd(td, uap)
1059 struct thread *td;
1060 struct __getcwd_args *uap;
1061{
1062
1063 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen));
1064}
1065
1066int
1067kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen)
1068{
1069 char *bp, *tmpbuf;
1070 struct filedesc *fdp;
1071 struct vnode *cdir, *rdir;
| 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
64SDT_PROVIDER_DECLARE(vfs);
65SDT_PROBE_DEFINE3(vfs, namecache, enter, done, done, "struct vnode *", "char *",
66 "struct vnode *");
67SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, done, "struct vnode *",
68 "char *");
69SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, entry, "struct vnode *");
70SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, hit, "struct vnode *",
71 "struct char *", "struct vnode *");
72SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, miss, "struct vnode *");
73SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, return, "int",
74 "struct vnode *", "struct char *");
75SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, hit, "struct vnode *", "char *",
76 "struct vnode *");
77SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit_negative, hit-negative,
78 "struct vnode *", "char *");
79SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, miss, "struct vnode *",
80 "char *");
81SDT_PROBE_DEFINE1(vfs, namecache, purge, done, done, "struct vnode *");
82SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, done, "struct vnode *");
83SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, done, "struct mount *");
84SDT_PROBE_DEFINE3(vfs, namecache, zap, done, done, "struct vnode *", "char *",
85 "struct vnode *");
86SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, 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
94struct 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 */
113struct 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])
157static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */
158static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */
159static u_long nchash; /* size of hash table */
160SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0,
161 "Size of namecache hash table");
162static u_long ncnegfactor = 16; /* ratio of negative entries */
163SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0,
164 "Ratio of negative namecache entries");
165static u_long numneg; /* number of negative entries allocated */
166SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0,
167 "Number of negative entries in namecache");
168static u_long numcache; /* number of cache entries allocated */
169SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0,
170 "Number of namecache entries");
171static u_long numcachehv; /* number of cache entries with vnodes held */
172SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0,
173 "Number of namecache entries with vnodes held");
174static u_int ncsizefactor = 2;
175SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0,
176 "Size factor for namecache");
177
178struct nchstats nchstats; /* cache effectiveness statistics */
179
180static struct rwlock cache_lock;
181RW_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 */
196static uma_zone_t cache_zone_small;
197static uma_zone_t cache_zone_small_ts;
198static uma_zone_t cache_zone_large;
199static uma_zone_t cache_zone_large_ts;
200
201#define CACHE_PATH_CUTOFF 35
202
203static struct namecache *
204cache_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
219static void
220cache_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
238static char *
239nc_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
249static void
250cache_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
263static int doingcache = 1; /* 1 => enable the cache */
264SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0,
265 "VFS namecache enabled");
266
267/* Export size information to userland */
268SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, 0,
269 sizeof(struct namecache), "sizeof(struct namecache)");
270
271/*
272 * The new name cache statistics
273 */
274static 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);
278STATNODE(CTLFLAG_RD, numneg, &numneg, "Number of negative cache entries");
279STATNODE(CTLFLAG_RD, numcache, &numcache, "Number of cache entries");
280static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls,
281 "Number of cache lookups");
282static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits,
283 "Number of '.' hits");
284static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits,
285 "Number of '..' hits");
286static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks,
287 "Number of checks in lookup");
288static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss,
289 "Number of cache misses");
290static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap,
291 "Number of cache misses we do not want to cache");
292static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps,
293 "Number of cache hits (positive) we do not want to cache");
294static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits,
295 "Number of cache hits (positive)");
296static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps,
297 "Number of cache hits (negative) we do not want to cache");
298static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits,
299 "Number of cache hits (negative)");
300static u_long numupgrades; STATNODE(CTLFLAG_RD, numupgrades, &numupgrades,
301 "Number of updates of the cache after lookup (write lock + retry)");
302
303SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD | CTLFLAG_MPSAFE,
304 &nchstats, sizeof(nchstats), "LU",
305 "VFS cache effectiveness statistics");
306
307
308
309static void cache_zap(struct namecache *ncp);
310static int vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf,
311 u_int *buflen);
312static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir,
313 char *buf, char **retbuf, u_int buflen);
314
315static 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 */
321static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL,
322 "hash table stats");
323
324static int
325sysctl_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}
351SYSCTL_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
355static int
356sysctl_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}
400SYSCTL_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 */
411static void
412cache_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
471int
472cache_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 }
487retry:
488 CACHE_RLOCK();
489 wlocked = 0;
490 numcalls++;
491 error = 0;
492
493retry_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
591negative_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
623wlock:
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
634success:
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
694unlock:
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 */
705void
706cache_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 if (vp != NULL)
758 TAILQ_INSERT_HEAD(&vp->v_cache_dst,
759 ncp, nc_dst);
760 else
761 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
762 ncp->nc_vp = vp;
763 CACHE_WUNLOCK();
764 return;
765 }
766 dvp->v_cache_dd = NULL;
767 SDT_PROBE(vfs, namecache, enter, done, dvp, "..", vp,
768 0, 0);
769 CACHE_WUNLOCK();
770 flag = NCF_ISDOTDOT;
771 }
772 }
773
774 hold = 0;
775 zap = 0;
776
777 /*
778 * Calculate the hash key and setup as much of the new
779 * namecache entry as possible before acquiring the lock.
780 */
781 ncp = cache_alloc(cnp->cn_namelen, tsp != NULL);
782 ncp->nc_vp = vp;
783 ncp->nc_dvp = dvp;
784 ncp->nc_flag = flag;
785 if (tsp != NULL) {
786 n3 = (struct namecache_ts *)ncp;
787 n3->nc_time = *tsp;
788 n3->nc_ticks = ticks;
789 n3->nc_flag |= NCF_TS;
790 if (dtsp != NULL) {
791 n3->nc_dotdottime = *dtsp;
792 n3->nc_flag |= NCF_DTS;
793 }
794 }
795 len = ncp->nc_nlen = cnp->cn_namelen;
796 hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT);
797 strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1);
798 hash = fnv_32_buf(&dvp, sizeof(dvp), hash);
799 CACHE_WLOCK();
800
801 /*
802 * See if this vnode or negative entry is already in the cache
803 * with this name. This can happen with concurrent lookups of
804 * the same path name.
805 */
806 ncpp = NCHHASH(hash);
807 LIST_FOREACH(n2, ncpp, nc_hash) {
808 if (n2->nc_dvp == dvp &&
809 n2->nc_nlen == cnp->cn_namelen &&
810 !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) {
811 if (tsp != NULL) {
812 KASSERT((n2->nc_flag & NCF_TS) != 0,
813 ("no NCF_TS"));
814 n3 = (struct namecache_ts *)n2;
815 n3->nc_time =
816 ((struct namecache_ts *)ncp)->nc_time;
817 n3->nc_ticks =
818 ((struct namecache_ts *)ncp)->nc_ticks;
819 if (dtsp != NULL) {
820 n3->nc_dotdottime =
821 ((struct namecache_ts *)ncp)->
822 nc_dotdottime;
823 n3->nc_flag |= NCF_DTS;
824 }
825 }
826 CACHE_WUNLOCK();
827 cache_free(ncp);
828 return;
829 }
830 }
831
832 if (flag == NCF_ISDOTDOT) {
833 /*
834 * See if we are trying to add .. entry, but some other lookup
835 * has populated v_cache_dd pointer already.
836 */
837 if (dvp->v_cache_dd != NULL) {
838 CACHE_WUNLOCK();
839 cache_free(ncp);
840 return;
841 }
842 KASSERT(vp == NULL || vp->v_type == VDIR,
843 ("wrong vnode type %p", vp));
844 dvp->v_cache_dd = ncp;
845 }
846
847 numcache++;
848 if (!vp) {
849 numneg++;
850 if (cnp->cn_flags & ISWHITEOUT)
851 ncp->nc_flag |= NCF_WHITE;
852 } else if (vp->v_type == VDIR) {
853 if (flag != NCF_ISDOTDOT) {
854 /*
855 * For this case, the cache entry maps both the
856 * directory name in it and the name ".." for the
857 * directory's parent.
858 */
859 if ((n2 = vp->v_cache_dd) != NULL &&
860 (n2->nc_flag & NCF_ISDOTDOT) != 0)
861 cache_zap(n2);
862 vp->v_cache_dd = ncp;
863 }
864 } else {
865 vp->v_cache_dd = NULL;
866 }
867
868 /*
869 * Insert the new namecache entry into the appropriate chain
870 * within the cache entries table.
871 */
872 LIST_INSERT_HEAD(ncpp, ncp, nc_hash);
873 if (flag != NCF_ISDOTDOT) {
874 if (LIST_EMPTY(&dvp->v_cache_src)) {
875 hold = 1;
876 numcachehv++;
877 }
878 LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src);
879 }
880
881 /*
882 * If the entry is "negative", we place it into the
883 * "negative" cache queue, otherwise, we place it into the
884 * destination vnode's cache entries queue.
885 */
886 if (vp) {
887 TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst);
888 SDT_PROBE(vfs, namecache, enter, done, dvp, nc_get_name(ncp),
889 vp, 0, 0);
890 } else {
891 TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst);
892 SDT_PROBE(vfs, namecache, enter_negative, done, dvp,
893 nc_get_name(ncp), 0, 0, 0);
894 }
895 if (numneg * ncnegfactor > numcache) {
896 ncp = TAILQ_FIRST(&ncneg);
897 zap = 1;
898 }
899 if (hold)
900 vhold(dvp);
901 if (zap)
902 cache_zap(ncp);
903 CACHE_WUNLOCK();
904}
905
906/*
907 * Name cache initialization, from vfs_init() when we are booting
908 */
909static void
910nchinit(void *dummy __unused)
911{
912
913 TAILQ_INIT(&ncneg);
914
915 cache_zone_small = uma_zcreate("S VFS Cache",
916 sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1,
917 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
918 cache_zone_small_ts = uma_zcreate("STS VFS Cache",
919 sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1,
920 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
921 cache_zone_large = uma_zcreate("L VFS Cache",
922 sizeof(struct namecache) + NAME_MAX + 1,
923 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
924 cache_zone_large_ts = uma_zcreate("LTS VFS Cache",
925 sizeof(struct namecache_ts) + NAME_MAX + 1,
926 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT);
927
928 nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash);
929}
930SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL);
931
932
933/*
934 * Invalidate all entries to a particular vnode.
935 */
936void
937cache_purge(vp)
938 struct vnode *vp;
939{
940
941 CTR1(KTR_VFS, "cache_purge(%p)", vp);
942 SDT_PROBE(vfs, namecache, purge, done, vp, 0, 0, 0, 0);
943 CACHE_WLOCK();
944 while (!LIST_EMPTY(&vp->v_cache_src))
945 cache_zap(LIST_FIRST(&vp->v_cache_src));
946 while (!TAILQ_EMPTY(&vp->v_cache_dst))
947 cache_zap(TAILQ_FIRST(&vp->v_cache_dst));
948 if (vp->v_cache_dd != NULL) {
949 KASSERT(vp->v_cache_dd->nc_flag & NCF_ISDOTDOT,
950 ("lost dotdot link"));
951 cache_zap(vp->v_cache_dd);
952 }
953 KASSERT(vp->v_cache_dd == NULL, ("incomplete purge"));
954 CACHE_WUNLOCK();
955}
956
957/*
958 * Invalidate all negative entries for a particular directory vnode.
959 */
960void
961cache_purge_negative(vp)
962 struct vnode *vp;
963{
964 struct namecache *cp, *ncp;
965
966 CTR1(KTR_VFS, "cache_purge_negative(%p)", vp);
967 SDT_PROBE(vfs, namecache, purge_negative, done, vp, 0, 0, 0, 0);
968 CACHE_WLOCK();
969 LIST_FOREACH_SAFE(cp, &vp->v_cache_src, nc_src, ncp) {
970 if (cp->nc_vp == NULL)
971 cache_zap(cp);
972 }
973 CACHE_WUNLOCK();
974}
975
976/*
977 * Flush all entries referencing a particular filesystem.
978 */
979void
980cache_purgevfs(mp)
981 struct mount *mp;
982{
983 struct nchashhead *ncpp;
984 struct namecache *ncp, *nnp;
985
986 /* Scan hash tables for applicable entries */
987 SDT_PROBE(vfs, namecache, purgevfs, done, mp, 0, 0, 0, 0);
988 CACHE_WLOCK();
989 for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) {
990 LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) {
991 if (ncp->nc_dvp->v_mount == mp)
992 cache_zap(ncp);
993 }
994 }
995 CACHE_WUNLOCK();
996}
997
998/*
999 * Perform canonical checks and cache lookup and pass on to filesystem
1000 * through the vop_cachedlookup only if needed.
1001 */
1002
1003int
1004vfs_cache_lookup(ap)
1005 struct vop_lookup_args /* {
1006 struct vnode *a_dvp;
1007 struct vnode **a_vpp;
1008 struct componentname *a_cnp;
1009 } */ *ap;
1010{
1011 struct vnode *dvp;
1012 int error;
1013 struct vnode **vpp = ap->a_vpp;
1014 struct componentname *cnp = ap->a_cnp;
1015 struct ucred *cred = cnp->cn_cred;
1016 int flags = cnp->cn_flags;
1017 struct thread *td = cnp->cn_thread;
1018
1019 *vpp = NULL;
1020 dvp = ap->a_dvp;
1021
1022 if (dvp->v_type != VDIR)
1023 return (ENOTDIR);
1024
1025 if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
1026 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
1027 return (EROFS);
1028
1029 error = VOP_ACCESS(dvp, VEXEC, cred, td);
1030 if (error)
1031 return (error);
1032
1033 error = cache_lookup(dvp, vpp, cnp, NULL, NULL);
1034 if (error == 0)
1035 return (VOP_CACHEDLOOKUP(dvp, vpp, cnp));
1036 if (error == -1)
1037 return (0);
1038 return (error);
1039}
1040
1041
1042#ifndef _SYS_SYSPROTO_H_
1043struct __getcwd_args {
1044 u_char *buf;
1045 u_int buflen;
1046};
1047#endif
1048
1049/*
1050 * XXX All of these sysctls would probably be more productive dead.
1051 */
1052static int disablecwd;
1053SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0,
1054 "Disable the getcwd syscall");
1055
1056/* Implementation of the getcwd syscall. */
1057int
1058sys___getcwd(td, uap)
1059 struct thread *td;
1060 struct __getcwd_args *uap;
1061{
1062
1063 return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen));
1064}
1065
1066int
1067kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg, u_int buflen)
1068{
1069 char *bp, *tmpbuf;
1070 struct filedesc *fdp;
1071 struct vnode *cdir, *rdir;
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