2 * Copyright (c) 2003,2004,2009 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * Copyright (c) 1989, 1993, 1995
35 * The Regents of the University of California. All rights reserved.
37 * This code is derived from software contributed to Berkeley by
38 * Poul-Henning Kamp of the FreeBSD Project.
40 * Redistribution and use in source and binary forms, with or without
41 * modification, are permitted provided that the following conditions
43 * 1. Redistributions of source code must retain the above copyright
44 * notice, this list of conditions and the following disclaimer.
45 * 2. Redistributions in binary form must reproduce the above copyright
46 * notice, this list of conditions and the following disclaimer in the
47 * documentation and/or other materials provided with the distribution.
48 * 3. Neither the name of the University nor the names of its contributors
49 * may be used to endorse or promote products derived from this software
50 * without specific prior written permission.
52 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
53 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
55 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
56 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
57 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
58 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
59 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
60 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
61 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
65 #include <sys/param.h>
66 #include <sys/systm.h>
67 #include <sys/kernel.h>
68 #include <sys/sysctl.h>
69 #include <sys/mount.h>
70 #include <sys/vnode.h>
71 #include <sys/malloc.h>
72 #include <sys/sysproto.h>
73 #include <sys/spinlock.h>
75 #include <sys/namei.h>
76 #include <sys/nlookup.h>
77 #include <sys/filedesc.h>
78 #include <sys/fnv_hash.h>
79 #include <sys/globaldata.h>
80 #include <sys/kern_syscall.h>
81 #include <sys/dirent.h>
84 #include <sys/sysref2.h>
85 #include <sys/spinlock2.h>
87 #define MAX_RECURSION_DEPTH 64
90 * Random lookups in the cache are accomplished with a hash table using
91 * a hash key of (nc_src_vp, name). Each hash chain has its own spin lock.
93 * Negative entries may exist and correspond to resolved namecache
94 * structures where nc_vp is NULL. In a negative entry, NCF_WHITEOUT
95 * will be set if the entry corresponds to a whited-out directory entry
96 * (verses simply not finding the entry at all). ncneg.list is locked
97 * with a global spinlock (ncneg.spin).
101 * (1) A ncp must be referenced before it can be locked.
103 * (2) A ncp must be locked in order to modify it.
105 * (3) ncp locks are always ordered child -> parent. That may seem
106 * backwards but forward scans use the hash table and thus can hold
107 * the parent unlocked when traversing downward.
109 * This allows insert/rename/delete/dot-dot and other operations
110 * to use ncp->nc_parent links.
112 * This also prevents a locked up e.g. NFS node from creating a
113 * chain reaction all the way back to the root vnode / namecache.
115 * (4) parent linkages require both the parent and child to be locked.
119 * Structures associated with name cacheing.
121 #define NCHHASH(hash) (&nchashtbl[(hash) & nchash])
124 #define NCMOUNT_NUMCACHE 16301 /* prime number */
126 MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries");
128 LIST_HEAD(nchash_list, namecache);
131 * Don't cachealign, but at least pad to 32 bytes so entries
132 * don't cross a cache line.
135 struct nchash_list list; /* 16 bytes */
136 struct spinlock spin; /* 8 bytes */
137 long pad01; /* 8 bytes */
140 struct ncmount_cache {
141 struct spinlock spin;
142 struct namecache *ncp;
144 int isneg; /* if != 0 mp is originator and not target */
148 struct spinlock spin;
149 struct namecache_list list;
152 static struct nchash_head *nchashtbl;
153 static struct ncneg_cache ncneg;
154 static struct ncmount_cache ncmount_cache[NCMOUNT_NUMCACHE];
157 * ncvp_debug - debug cache_fromvp(). This is used by the NFS server
158 * to create the namecache infrastructure leading to a dangling vnode.
160 * 0 Only errors are reported
161 * 1 Successes are reported
162 * 2 Successes + the whole directory scan is reported
163 * 3 Force the directory scan code run as if the parent vnode did not
164 * have a namecache record, even if it does have one.
166 static int ncvp_debug;
167 SYSCTL_INT(_debug, OID_AUTO, ncvp_debug, CTLFLAG_RW, &ncvp_debug, 0,
168 "Namecache debug level (0-3)");
170 static u_long nchash; /* size of hash table */
171 SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0,
172 "Size of namecache hash table");
174 static int ncnegflush = 10; /* burst for negative flush */
175 SYSCTL_INT(_debug, OID_AUTO, ncnegflush, CTLFLAG_RW, &ncnegflush, 0,
176 "Batch flush negative entries");
178 static int ncposflush = 10; /* burst for positive flush */
179 SYSCTL_INT(_debug, OID_AUTO, ncposflush, CTLFLAG_RW, &ncposflush, 0,
180 "Batch flush positive entries");
182 static int ncnegfactor = 16; /* ratio of negative entries */
183 SYSCTL_INT(_debug, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0,
184 "Ratio of namecache negative entries");
186 static int nclockwarn; /* warn on locked entries in ticks */
187 SYSCTL_INT(_debug, OID_AUTO, nclockwarn, CTLFLAG_RW, &nclockwarn, 0,
188 "Warn on locked namecache entries in ticks");
190 static int numdefered; /* number of cache entries allocated */
191 SYSCTL_INT(_debug, OID_AUTO, numdefered, CTLFLAG_RD, &numdefered, 0,
192 "Number of cache entries allocated");
194 static int ncposlimit; /* number of cache entries allocated */
195 SYSCTL_INT(_debug, OID_AUTO, ncposlimit, CTLFLAG_RW, &ncposlimit, 0,
196 "Number of cache entries allocated");
198 static int ncp_shared_lock_disable = 0;
199 SYSCTL_INT(_debug, OID_AUTO, ncp_shared_lock_disable, CTLFLAG_RW,
200 &ncp_shared_lock_disable, 0, "Disable shared namecache locks");
202 SYSCTL_INT(_debug, OID_AUTO, vnsize, CTLFLAG_RD, 0, sizeof(struct vnode),
203 "sizeof(struct vnode)");
204 SYSCTL_INT(_debug, OID_AUTO, ncsize, CTLFLAG_RD, 0, sizeof(struct namecache),
205 "sizeof(struct namecache)");
207 static int ncmount_cache_enable = 1;
208 SYSCTL_INT(_debug, OID_AUTO, ncmount_cache_enable, CTLFLAG_RW,
209 &ncmount_cache_enable, 0, "mount point cache");
211 static __inline void _cache_drop(struct namecache *ncp);
212 static int cache_resolve_mp(struct mount *mp);
213 static struct vnode *cache_dvpref(struct namecache *ncp);
214 static void _cache_lock(struct namecache *ncp);
215 static void _cache_setunresolved(struct namecache *ncp);
216 static void _cache_cleanneg(int count);
217 static void _cache_cleanpos(int count);
218 static void _cache_cleandefered(void);
219 static void _cache_unlink(struct namecache *ncp);
222 * The new name cache statistics
224 SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics");
226 SYSCTL_INT(_vfs_cache, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0,
227 "Number of negative namecache entries");
229 SYSCTL_INT(_vfs_cache, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0,
230 "Number of namecaches entries");
232 struct nchstats nchstats[SMP_MAXCPU];
234 * Export VFS cache effectiveness statistics to user-land.
236 * The statistics are left for aggregation to user-land so
237 * neat things can be achieved, like observing per-CPU cache
241 sysctl_nchstats(SYSCTL_HANDLER_ARGS)
243 struct globaldata *gd;
247 for (i = 0; i < ncpus; ++i) {
248 gd = globaldata_find(i);
249 if ((error = SYSCTL_OUT(req, (void *)&(*gd->gd_nchstats),
250 sizeof(struct nchstats))))
256 SYSCTL_PROC(_vfs_cache, OID_AUTO, nchstats, CTLTYPE_OPAQUE|CTLFLAG_RD,
257 0, 0, sysctl_nchstats, "S,nchstats", "VFS cache effectiveness statistics");
259 static struct namecache *cache_zap(struct namecache *ncp, int nonblock);
262 * Cache mount points and namecache records in order to avoid unnecessary
263 * atomic ops on mnt_refs and ncp->refs. This improves concurrent SMP
264 * performance and is particularly important on multi-socket systems to
265 * reduce cache-line ping-ponging.
267 * Try to keep the pcpu structure within one cache line (~64 bytes).
269 #define MNTCACHE_COUNT 5
272 struct mount *mntary[MNTCACHE_COUNT];
273 struct namecache *ncp1;
274 struct namecache *ncp2;
275 struct nchandle ncdir;
280 static struct mntcache pcpu_mntcache[MAXCPU];
284 _cache_mntref(struct mount *mp)
286 struct mntcache *cache = &pcpu_mntcache[mycpu->gd_cpuid];
289 for (i = 0; i < MNTCACHE_COUNT; ++i) {
290 if (cache->mntary[i] != mp)
292 if (atomic_cmpset_ptr((void *)&cache->mntary[i], mp, NULL))
295 atomic_add_int(&mp->mnt_refs, 1);
300 _cache_mntrel(struct mount *mp)
302 struct mntcache *cache = &pcpu_mntcache[mycpu->gd_cpuid];
305 for (i = 0; i < MNTCACHE_COUNT; ++i) {
306 if (cache->mntary[i] == NULL) {
307 mp = atomic_swap_ptr((void *)&cache->mntary[i], mp);
312 i = (int)((uint32_t)++cache->iter % (uint32_t)MNTCACHE_COUNT);
313 mp = atomic_swap_ptr((void *)&cache->mntary[i], mp);
315 atomic_add_int(&mp->mnt_refs, -1);
319 * Clears all cached mount points on all cpus. This routine should only
320 * be called when we are waiting for a mount to clear, e.g. so we can
324 cache_clearmntcache(void)
328 for (n = 0; n < ncpus; ++n) {
329 struct mntcache *cache = &pcpu_mntcache[n];
330 struct namecache *ncp;
334 for (i = 0; i < MNTCACHE_COUNT; ++i) {
335 if (cache->mntary[i]) {
336 mp = atomic_swap_ptr(
337 (void *)&cache->mntary[i], NULL);
339 atomic_add_int(&mp->mnt_refs, -1);
343 ncp = atomic_swap_ptr((void *)&cache->ncp1, NULL);
348 ncp = atomic_swap_ptr((void *)&cache->ncp2, NULL);
352 if (cache->ncdir.ncp) {
353 ncp = atomic_swap_ptr((void *)&cache->ncdir.ncp, NULL);
357 if (cache->ncdir.mount) {
358 mp = atomic_swap_ptr((void *)&cache->ncdir.mount, NULL);
360 atomic_add_int(&mp->mnt_refs, -1);
367 * Namespace locking. The caller must already hold a reference to the
368 * namecache structure in order to lock/unlock it. This function prevents
369 * the namespace from being created or destroyed by accessors other then
372 * Note that holding a locked namecache structure prevents other threads
373 * from making namespace changes (e.g. deleting or creating), prevents
374 * vnode association state changes by other threads, and prevents the
375 * namecache entry from being resolved or unresolved by other threads.
377 * An exclusive lock owner has full authority to associate/disassociate
378 * vnodes and resolve/unresolve the locked ncp.
380 * A shared lock owner only has authority to acquire the underlying vnode,
383 * The primary lock field is nc_lockstatus. nc_locktd is set after the
384 * fact (when locking) or cleared prior to unlocking.
386 * WARNING! Holding a locked ncp will prevent a vnode from being destroyed
387 * or recycled, but it does NOT help you if the vnode had already
388 * initiated a recyclement. If this is important, use cache_get()
389 * rather then cache_lock() (and deal with the differences in the
390 * way the refs counter is handled). Or, alternatively, make an
391 * unconditional call to cache_validate() or cache_resolve()
392 * after cache_lock() returns.
396 _cache_lock(struct namecache *ncp)
404 KKASSERT(ncp->nc_refs != 0);
410 count = ncp->nc_lockstatus;
413 if ((count & ~(NC_EXLOCK_REQ|NC_SHLOCK_REQ)) == 0) {
414 if (atomic_cmpset_int(&ncp->nc_lockstatus,
417 * The vp associated with a locked ncp must
418 * be held to prevent it from being recycled.
420 * WARNING! If VRECLAIMED is set the vnode
421 * could already be in the middle of a recycle.
422 * Callers must use cache_vref() or
423 * cache_vget() on the locked ncp to
424 * validate the vp or set the cache entry
427 * NOTE! vhold() is allowed if we hold a
428 * lock on the ncp (which we do).
438 if (ncp->nc_locktd == td) {
439 KKASSERT((count & NC_SHLOCK_FLAG) == 0);
440 if (atomic_cmpset_int(&ncp->nc_lockstatus,
447 tsleep_interlock(&ncp->nc_locktd, 0);
448 if (atomic_cmpset_int(&ncp->nc_lockstatus, count,
449 count | NC_EXLOCK_REQ) == 0) {
455 error = tsleep(&ncp->nc_locktd, PINTERLOCKED,
456 "clock", nclockwarn);
457 if (error == EWOULDBLOCK) {
460 kprintf("[diagnostic] cache_lock: "
461 "%s blocked on %p %08x",
462 td->td_comm, ncp, count);
463 kprintf(" \"%*.*s\"\n",
464 ncp->nc_nlen, ncp->nc_nlen,
471 kprintf("[diagnostic] cache_lock: %s unblocked %*.*s after "
474 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name,
475 (int)(ticks + (hz / 2) - begticks) / hz);
480 * The shared lock works similarly to the exclusive lock except
481 * nc_locktd is left NULL and we need an interlock (VHOLD) to
482 * prevent vhold() races, since the moment our cmpset_int succeeds
483 * another cpu can come in and get its own shared lock.
485 * A critical section is needed to prevent interruption during the
490 _cache_lock_shared(struct namecache *ncp)
495 u_int optreq = NC_EXLOCK_REQ;
497 KKASSERT(ncp->nc_refs != 0);
501 count = ncp->nc_lockstatus;
504 if ((count & ~NC_SHLOCK_REQ) == 0) {
506 if (atomic_cmpset_int(&ncp->nc_lockstatus,
508 (count + 1) | NC_SHLOCK_FLAG |
511 * The vp associated with a locked ncp must
512 * be held to prevent it from being recycled.
514 * WARNING! If VRECLAIMED is set the vnode
515 * could already be in the middle of a recycle.
516 * Callers must use cache_vref() or
517 * cache_vget() on the locked ncp to
518 * validate the vp or set the cache entry
521 * NOTE! vhold() is allowed if we hold a
522 * lock on the ncp (which we do).
526 atomic_clear_int(&ncp->nc_lockstatus,
537 * If already held shared we can just bump the count, but
538 * only allow this if nobody is trying to get the lock
539 * exclusively. If we are blocking too long ignore excl
540 * requests (which can race/deadlock us).
542 * VHOLD is a bit of a hack. Even though we successfully
543 * added another shared ref, the cpu that got the first
544 * shared ref might not yet have held the vnode.
546 if ((count & (optreq|NC_SHLOCK_FLAG)) == NC_SHLOCK_FLAG) {
547 KKASSERT((count & ~(NC_EXLOCK_REQ |
549 NC_SHLOCK_FLAG)) > 0);
550 if (atomic_cmpset_int(&ncp->nc_lockstatus,
552 while (ncp->nc_lockstatus & NC_SHLOCK_VHOLD)
558 tsleep_interlock(ncp, 0);
559 if (atomic_cmpset_int(&ncp->nc_lockstatus, count,
560 count | NC_SHLOCK_REQ) == 0) {
564 error = tsleep(ncp, PINTERLOCKED, "clocksh", nclockwarn);
565 if (error == EWOULDBLOCK) {
568 didwarn = ticks - nclockwarn;
569 kprintf("[diagnostic] cache_lock_shared: "
570 "%s blocked on %p %08x",
571 curthread->td_comm, ncp, count);
572 kprintf(" \"%*.*s\"\n",
573 ncp->nc_nlen, ncp->nc_nlen,
580 kprintf("[diagnostic] cache_lock_shared: "
581 "%s unblocked %*.*s after %d secs\n",
583 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name,
584 (int)(ticks - didwarn) / hz);
589 * Lock ncp exclusively, return 0 on success.
591 * NOTE: nc_refs may be zero if the ncp is interlocked by circumstance,
592 * such as the case where one of its children is locked.
596 _cache_lock_nonblock(struct namecache *ncp)
604 count = ncp->nc_lockstatus;
606 if ((count & ~(NC_EXLOCK_REQ|NC_SHLOCK_REQ)) == 0) {
607 if (atomic_cmpset_int(&ncp->nc_lockstatus,
610 * The vp associated with a locked ncp must
611 * be held to prevent it from being recycled.
613 * WARNING! If VRECLAIMED is set the vnode
614 * could already be in the middle of a recycle.
615 * Callers must use cache_vref() or
616 * cache_vget() on the locked ncp to
617 * validate the vp or set the cache entry
620 * NOTE! vhold() is allowed if we hold a
621 * lock on the ncp (which we do).
631 if (ncp->nc_locktd == td) {
632 if (atomic_cmpset_int(&ncp->nc_lockstatus,
645 * The shared lock works similarly to the exclusive lock except
646 * nc_locktd is left NULL and we need an interlock (VHOLD) to
647 * prevent vhold() races, since the moment our cmpset_int succeeds
648 * another cpu can come in and get its own shared lock.
650 * A critical section is needed to prevent interruption during the
655 _cache_lock_shared_nonblock(struct namecache *ncp)
660 count = ncp->nc_lockstatus;
662 if ((count & ~NC_SHLOCK_REQ) == 0) {
664 if (atomic_cmpset_int(&ncp->nc_lockstatus,
666 (count + 1) | NC_SHLOCK_FLAG |
669 * The vp associated with a locked ncp must
670 * be held to prevent it from being recycled.
672 * WARNING! If VRECLAIMED is set the vnode
673 * could already be in the middle of a recycle.
674 * Callers must use cache_vref() or
675 * cache_vget() on the locked ncp to
676 * validate the vp or set the cache entry
679 * NOTE! vhold() is allowed if we hold a
680 * lock on the ncp (which we do).
684 atomic_clear_int(&ncp->nc_lockstatus,
695 * If already held shared we can just bump the count, but
696 * only allow this if nobody is trying to get the lock
699 * VHOLD is a bit of a hack. Even though we successfully
700 * added another shared ref, the cpu that got the first
701 * shared ref might not yet have held the vnode.
703 if ((count & (NC_EXLOCK_REQ|NC_SHLOCK_FLAG)) ==
705 KKASSERT((count & ~(NC_EXLOCK_REQ |
707 NC_SHLOCK_FLAG)) > 0);
708 if (atomic_cmpset_int(&ncp->nc_lockstatus,
710 while (ncp->nc_lockstatus & NC_SHLOCK_VHOLD)
724 * NOTE: nc_refs can be 0 (degenerate case during _cache_drop).
726 * nc_locktd must be NULLed out prior to nc_lockstatus getting cleared.
730 _cache_unlock(struct namecache *ncp)
732 thread_t td __debugvar = curthread;
735 struct vnode *dropvp;
737 KKASSERT(ncp->nc_refs >= 0);
738 KKASSERT((ncp->nc_lockstatus & ~(NC_EXLOCK_REQ|NC_SHLOCK_REQ)) > 0);
739 KKASSERT((ncp->nc_lockstatus & NC_SHLOCK_FLAG) || ncp->nc_locktd == td);
741 count = ncp->nc_lockstatus;
745 * Clear nc_locktd prior to the atomic op (excl lock only)
747 if ((count & ~(NC_EXLOCK_REQ|NC_SHLOCK_REQ)) == 1)
748 ncp->nc_locktd = NULL;
753 ~(NC_EXLOCK_REQ|NC_SHLOCK_REQ|NC_SHLOCK_FLAG)) == 1) {
755 if (count & NC_EXLOCK_REQ)
756 ncount = count & NC_SHLOCK_REQ; /* cnt->0 */
760 if (atomic_cmpset_int(&ncp->nc_lockstatus,
762 if (count & NC_EXLOCK_REQ)
763 wakeup(&ncp->nc_locktd);
764 else if (count & NC_SHLOCK_REQ)
770 KKASSERT((count & NC_SHLOCK_VHOLD) == 0);
771 KKASSERT((count & ~(NC_EXLOCK_REQ |
773 NC_SHLOCK_FLAG)) > 1);
774 if (atomic_cmpset_int(&ncp->nc_lockstatus,
779 count = ncp->nc_lockstatus;
784 * Don't actually drop the vp until we successfully clean out
785 * the lock, otherwise we may race another shared lock.
793 _cache_lockstatus(struct namecache *ncp)
795 if (ncp->nc_locktd == curthread)
796 return(LK_EXCLUSIVE);
797 if (ncp->nc_lockstatus & NC_SHLOCK_FLAG)
803 * cache_hold() and cache_drop() prevent the premature deletion of a
804 * namecache entry but do not prevent operations (such as zapping) on
805 * that namecache entry.
807 * This routine may only be called from outside this source module if
808 * nc_refs is already at least 1.
810 * This is a rare case where callers are allowed to hold a spinlock,
811 * so we can't ourselves.
815 _cache_hold(struct namecache *ncp)
817 atomic_add_int(&ncp->nc_refs, 1);
822 * Drop a cache entry, taking care to deal with races.
824 * For potential 1->0 transitions we must hold the ncp lock to safely
825 * test its flags. An unresolved entry with no children must be zapped
828 * The call to cache_zap() itself will handle all remaining races and
829 * will decrement the ncp's refs regardless. If we are resolved or
830 * have children nc_refs can safely be dropped to 0 without having to
833 * NOTE: cache_zap() will re-check nc_refs and nc_list in a MPSAFE fashion.
835 * NOTE: cache_zap() may return a non-NULL referenced parent which must
836 * be dropped in a loop.
840 _cache_drop(struct namecache *ncp)
845 KKASSERT(ncp->nc_refs > 0);
849 if (_cache_lock_nonblock(ncp) == 0) {
850 ncp->nc_flag &= ~NCF_DEFEREDZAP;
851 if ((ncp->nc_flag & NCF_UNRESOLVED) &&
852 TAILQ_EMPTY(&ncp->nc_list)) {
853 ncp = cache_zap(ncp, 1);
856 if (atomic_cmpset_int(&ncp->nc_refs, 1, 0)) {
863 if (atomic_cmpset_int(&ncp->nc_refs, refs, refs - 1))
871 * Link a new namecache entry to its parent and to the hash table. Be
872 * careful to avoid races if vhold() blocks in the future.
874 * Both ncp and par must be referenced and locked.
876 * NOTE: The hash table spinlock is held during this call, we can't do
880 _cache_link_parent(struct namecache *ncp, struct namecache *par,
881 struct nchash_head *nchpp)
883 KKASSERT(ncp->nc_parent == NULL);
884 ncp->nc_parent = par;
885 ncp->nc_head = nchpp;
888 * Set inheritance flags. Note that the parent flags may be
889 * stale due to getattr potentially not having been run yet
890 * (it gets run during nlookup()'s).
892 ncp->nc_flag &= ~(NCF_SF_PNOCACHE | NCF_UF_PCACHE);
893 if (par->nc_flag & (NCF_SF_NOCACHE | NCF_SF_PNOCACHE))
894 ncp->nc_flag |= NCF_SF_PNOCACHE;
895 if (par->nc_flag & (NCF_UF_CACHE | NCF_UF_PCACHE))
896 ncp->nc_flag |= NCF_UF_PCACHE;
898 LIST_INSERT_HEAD(&nchpp->list, ncp, nc_hash);
900 if (TAILQ_EMPTY(&par->nc_list)) {
901 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry);
903 * Any vp associated with an ncp which has children must
904 * be held to prevent it from being recycled.
909 TAILQ_INSERT_HEAD(&par->nc_list, ncp, nc_entry);
914 * Remove the parent and hash associations from a namecache structure.
915 * If this is the last child of the parent the cache_drop(par) will
916 * attempt to recursively zap the parent.
918 * ncp must be locked. This routine will acquire a temporary lock on
919 * the parent as wlel as the appropriate hash chain.
922 _cache_unlink_parent(struct namecache *ncp)
924 struct namecache *par;
925 struct vnode *dropvp;
927 if ((par = ncp->nc_parent) != NULL) {
928 KKASSERT(ncp->nc_parent == par);
931 spin_lock(&ncp->nc_head->spin);
932 LIST_REMOVE(ncp, nc_hash);
933 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry);
935 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list))
937 spin_unlock(&ncp->nc_head->spin);
938 ncp->nc_parent = NULL;
944 * We can only safely vdrop with no spinlocks held.
952 * Allocate a new namecache structure. Most of the code does not require
953 * zero-termination of the string but it makes vop_compat_ncreate() easier.
955 static struct namecache *
956 cache_alloc(int nlen)
958 struct namecache *ncp;
960 ncp = kmalloc(sizeof(*ncp), M_VFSCACHE, M_WAITOK|M_ZERO);
962 ncp->nc_name = kmalloc(nlen + 1, M_VFSCACHE, M_WAITOK);
964 ncp->nc_flag = NCF_UNRESOLVED;
965 ncp->nc_error = ENOTCONN; /* needs to be resolved */
968 TAILQ_INIT(&ncp->nc_list);
974 * Can only be called for the case where the ncp has never been
975 * associated with anything (so no spinlocks are needed).
978 _cache_free(struct namecache *ncp)
980 KKASSERT(ncp->nc_refs == 1 && ncp->nc_lockstatus == 1);
982 kfree(ncp->nc_name, M_VFSCACHE);
983 kfree(ncp, M_VFSCACHE);
987 * [re]initialize a nchandle.
990 cache_zero(struct nchandle *nch)
997 * Ref and deref a namecache structure.
999 * The caller must specify a stable ncp pointer, typically meaning the
1000 * ncp is already referenced but this can also occur indirectly through
1001 * e.g. holding a lock on a direct child.
1003 * WARNING: Caller may hold an unrelated read spinlock, which means we can't
1004 * use read spinlocks here.
1007 cache_hold(struct nchandle *nch)
1009 _cache_hold(nch->ncp);
1010 _cache_mntref(nch->mount);
1015 * Create a copy of a namecache handle for an already-referenced
1019 cache_copy(struct nchandle *nch, struct nchandle *target)
1021 struct mntcache *cache = &pcpu_mntcache[mycpu->gd_cpuid];
1022 struct namecache *ncp;
1025 _cache_mntref(target->mount);
1028 if (ncp == cache->ncp1) {
1029 if (atomic_cmpset_ptr((void *)&cache->ncp1, ncp, NULL))
1032 if (ncp == cache->ncp2) {
1033 if (atomic_cmpset_ptr((void *)&cache->ncp2, ncp, NULL))
1041 * Caller wants to copy the current directory, copy it out from our
1042 * pcpu cache if possible (the entire critical path is just two localized
1043 * cmpset ops). If the pcpu cache has a snapshot at all it will be a
1044 * valid one, so we don't have to lock p->p_fd even though we are loading
1047 * This has a limited effect since nlookup must still ref and shlock the
1048 * vnode to check perms. We do avoid the per-proc spin-lock though, which
1049 * can aid threaded programs.
1052 cache_copy_ncdir(struct proc *p, struct nchandle *target)
1054 struct mntcache *cache = &pcpu_mntcache[mycpu->gd_cpuid];
1056 *target = p->p_fd->fd_ncdir;
1057 if (target->ncp == cache->ncdir.ncp &&
1058 target->mount == cache->ncdir.mount) {
1059 if (atomic_cmpset_ptr((void *)&cache->ncdir.ncp,
1060 target->ncp, NULL)) {
1061 if (atomic_cmpset_ptr((void *)&cache->ncdir.mount,
1062 target->mount, NULL)) {
1066 _cache_drop(target->ncp);
1069 spin_lock_shared(&p->p_fd->fd_spin);
1070 cache_copy(&p->p_fd->fd_ncdir, target);
1071 spin_unlock_shared(&p->p_fd->fd_spin);
1075 cache_changemount(struct nchandle *nch, struct mount *mp)
1078 _cache_mntrel(nch->mount);
1083 cache_drop(struct nchandle *nch)
1085 _cache_mntrel(nch->mount);
1086 _cache_drop(nch->ncp);
1092 * Drop the nchandle, but try to cache the ref to avoid global atomic
1093 * ops. This is typically done on the system root and jail root nchandles.
1096 cache_drop_and_cache(struct nchandle *nch)
1098 struct mntcache *cache = &pcpu_mntcache[mycpu->gd_cpuid];
1099 struct namecache *ncp;
1101 _cache_mntrel(nch->mount);
1103 if (cache->ncp1 == NULL) {
1104 ncp = atomic_swap_ptr((void *)&cache->ncp1, ncp);
1108 if (cache->ncp2 == NULL) {
1109 ncp = atomic_swap_ptr((void *)&cache->ncp2, ncp);
1113 if (++cache->iter & 1)
1114 ncp = atomic_swap_ptr((void *)&cache->ncp2, ncp);
1116 ncp = atomic_swap_ptr((void *)&cache->ncp1, ncp);
1125 * We are dropping what the caller believes is the current directory,
1126 * unconditionally store it in our pcpu cache. Anything already in
1127 * the cache will be discarded.
1130 cache_drop_ncdir(struct nchandle *nch)
1132 struct mntcache *cache = &pcpu_mntcache[mycpu->gd_cpuid];
1134 nch->ncp = atomic_swap_ptr((void *)&cache->ncdir.ncp, nch->ncp);
1135 nch->mount = atomic_swap_ptr((void *)&cache->ncdir.mount, nch->mount);
1137 _cache_drop(nch->ncp);
1139 _cache_mntrel(nch->mount);
1145 cache_lockstatus(struct nchandle *nch)
1147 return(_cache_lockstatus(nch->ncp));
1151 cache_lock(struct nchandle *nch)
1153 _cache_lock(nch->ncp);
1157 cache_lock_maybe_shared(struct nchandle *nch, int excl)
1159 struct namecache *ncp = nch->ncp;
1161 if (ncp_shared_lock_disable || excl ||
1162 (ncp->nc_flag & NCF_UNRESOLVED)) {
1165 _cache_lock_shared(ncp);
1166 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
1167 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) {
1179 * Relock nch1 given an unlocked nch1 and a locked nch2. The caller
1180 * is responsible for checking both for validity on return as they
1181 * may have become invalid.
1183 * We have to deal with potential deadlocks here, just ping pong
1184 * the lock until we get it (we will always block somewhere when
1185 * looping so this is not cpu-intensive).
1187 * which = 0 nch1 not locked, nch2 is locked
1188 * which = 1 nch1 is locked, nch2 is not locked
1191 cache_relock(struct nchandle *nch1, struct ucred *cred1,
1192 struct nchandle *nch2, struct ucred *cred2)
1200 if (cache_lock_nonblock(nch1) == 0) {
1201 cache_resolve(nch1, cred1);
1206 cache_resolve(nch1, cred1);
1209 if (cache_lock_nonblock(nch2) == 0) {
1210 cache_resolve(nch2, cred2);
1215 cache_resolve(nch2, cred2);
1222 cache_lock_nonblock(struct nchandle *nch)
1224 return(_cache_lock_nonblock(nch->ncp));
1228 cache_unlock(struct nchandle *nch)
1230 _cache_unlock(nch->ncp);
1234 * ref-and-lock, unlock-and-deref functions.
1236 * This function is primarily used by nlookup. Even though cache_lock
1237 * holds the vnode, it is possible that the vnode may have already
1238 * initiated a recyclement.
1240 * We want cache_get() to return a definitively usable vnode or a
1241 * definitively unresolved ncp.
1245 _cache_get(struct namecache *ncp)
1249 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
1250 _cache_setunresolved(ncp);
1255 * Attempt to obtain a shared lock on the ncp. A shared lock will only
1256 * be obtained if the ncp is resolved and the vnode (if not ENOENT) is
1257 * valid. Otherwise an exclusive lock will be acquired instead.
1261 _cache_get_maybe_shared(struct namecache *ncp, int excl)
1263 if (ncp_shared_lock_disable || excl ||
1264 (ncp->nc_flag & NCF_UNRESOLVED)) {
1265 return(_cache_get(ncp));
1268 _cache_lock_shared(ncp);
1269 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
1270 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED)) {
1272 ncp = _cache_get(ncp);
1277 ncp = _cache_get(ncp);
1284 * This is a special form of _cache_lock() which only succeeds if
1285 * it can get a pristine, non-recursive lock. The caller must have
1286 * already ref'd the ncp.
1288 * On success the ncp will be locked, on failure it will not. The
1289 * ref count does not change either way.
1291 * We want _cache_lock_special() (on success) to return a definitively
1292 * usable vnode or a definitively unresolved ncp.
1295 _cache_lock_special(struct namecache *ncp)
1297 if (_cache_lock_nonblock(ncp) == 0) {
1298 if ((ncp->nc_lockstatus &
1299 ~(NC_EXLOCK_REQ|NC_SHLOCK_REQ)) == 1) {
1300 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
1301 _cache_setunresolved(ncp);
1306 return(EWOULDBLOCK);
1310 * This function tries to get a shared lock but will back-off to an exclusive
1313 * (1) Some other thread is trying to obtain an exclusive lock
1314 * (to prevent the exclusive requester from getting livelocked out
1315 * by many shared locks).
1317 * (2) The current thread already owns an exclusive lock (to avoid
1320 * WARNING! On machines with lots of cores we really want to try hard to
1321 * get a shared lock or concurrent path lookups can chain-react
1322 * into a very high-latency exclusive lock.
1325 _cache_lock_shared_special(struct namecache *ncp)
1328 * Only honor a successful shared lock (returning 0) if there is
1329 * no exclusive request pending and the vnode, if present, is not
1330 * in a reclaimed state.
1332 if (_cache_lock_shared_nonblock(ncp) == 0) {
1333 if ((ncp->nc_lockstatus & NC_EXLOCK_REQ) == 0) {
1334 if (ncp->nc_vp == NULL ||
1335 (ncp->nc_vp->v_flag & VRECLAIMED) == 0) {
1340 return(EWOULDBLOCK);
1344 * Non-blocking shared lock failed. If we already own the exclusive
1345 * lock just acquire another exclusive lock (instead of deadlocking).
1346 * Otherwise acquire a shared lock.
1348 if (ncp->nc_locktd == curthread) {
1352 _cache_lock_shared(ncp);
1358 * NOTE: The same nchandle can be passed for both arguments.
1361 cache_get(struct nchandle *nch, struct nchandle *target)
1363 KKASSERT(nch->ncp->nc_refs > 0);
1364 target->mount = nch->mount;
1365 target->ncp = _cache_get(nch->ncp);
1366 _cache_mntref(target->mount);
1370 cache_get_maybe_shared(struct nchandle *nch, struct nchandle *target, int excl)
1372 KKASSERT(nch->ncp->nc_refs > 0);
1373 target->mount = nch->mount;
1374 target->ncp = _cache_get_maybe_shared(nch->ncp, excl);
1375 _cache_mntref(target->mount);
1383 _cache_put(struct namecache *ncp)
1393 cache_put(struct nchandle *nch)
1395 _cache_mntrel(nch->mount);
1396 _cache_put(nch->ncp);
1402 * Resolve an unresolved ncp by associating a vnode with it. If the
1403 * vnode is NULL, a negative cache entry is created.
1405 * The ncp should be locked on entry and will remain locked on return.
1409 _cache_setvp(struct mount *mp, struct namecache *ncp, struct vnode *vp)
1411 KKASSERT(ncp->nc_flag & NCF_UNRESOLVED);
1412 KKASSERT(_cache_lockstatus(ncp) == LK_EXCLUSIVE);
1416 * Any vp associated with an ncp which has children must
1417 * be held. Any vp associated with a locked ncp must be held.
1419 if (!TAILQ_EMPTY(&ncp->nc_list))
1421 spin_lock(&vp->v_spin);
1423 TAILQ_INSERT_HEAD(&vp->v_namecache, ncp, nc_vnode);
1424 spin_unlock(&vp->v_spin);
1425 if (ncp->nc_lockstatus & ~(NC_EXLOCK_REQ|NC_SHLOCK_REQ))
1429 * Set auxiliary flags
1431 switch(vp->v_type) {
1433 ncp->nc_flag |= NCF_ISDIR;
1436 ncp->nc_flag |= NCF_ISSYMLINK;
1437 /* XXX cache the contents of the symlink */
1442 atomic_add_int(&numcache, 1);
1444 /* XXX: this is a hack to work-around the lack of a real pfs vfs
1447 if (strncmp(mp->mnt_stat.f_fstypename, "null", 5) == 0)
1451 * When creating a negative cache hit we set the
1452 * namecache_gen. A later resolve will clean out the
1453 * negative cache hit if the mount point's namecache_gen
1454 * has changed. Used by devfs, could also be used by
1458 spin_lock(&ncneg.spin);
1459 TAILQ_INSERT_TAIL(&ncneg.list, ncp, nc_vnode);
1461 spin_unlock(&ncneg.spin);
1462 ncp->nc_error = ENOENT;
1464 VFS_NCPGEN_SET(mp, ncp);
1466 ncp->nc_flag &= ~(NCF_UNRESOLVED | NCF_DEFEREDZAP);
1473 cache_setvp(struct nchandle *nch, struct vnode *vp)
1475 _cache_setvp(nch->mount, nch->ncp, vp);
1482 cache_settimeout(struct nchandle *nch, int nticks)
1484 struct namecache *ncp = nch->ncp;
1486 if ((ncp->nc_timeout = ticks + nticks) == 0)
1487 ncp->nc_timeout = 1;
1491 * Disassociate the vnode or negative-cache association and mark a
1492 * namecache entry as unresolved again. Note that the ncp is still
1493 * left in the hash table and still linked to its parent.
1495 * The ncp should be locked and refd on entry and will remain locked and refd
1498 * This routine is normally never called on a directory containing children.
1499 * However, NFS often does just that in its rename() code as a cop-out to
1500 * avoid complex namespace operations. This disconnects a directory vnode
1501 * from its namecache and can cause the OLDAPI and NEWAPI to get out of
1507 _cache_setunresolved(struct namecache *ncp)
1511 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
1512 ncp->nc_flag |= NCF_UNRESOLVED;
1513 ncp->nc_timeout = 0;
1514 ncp->nc_error = ENOTCONN;
1515 if ((vp = ncp->nc_vp) != NULL) {
1516 atomic_add_int(&numcache, -1);
1517 spin_lock(&vp->v_spin);
1519 TAILQ_REMOVE(&vp->v_namecache, ncp, nc_vnode);
1520 spin_unlock(&vp->v_spin);
1523 * Any vp associated with an ncp with children is
1524 * held by that ncp. Any vp associated with a locked
1525 * ncp is held by that ncp. These conditions must be
1526 * undone when the vp is cleared out from the ncp.
1528 if (!TAILQ_EMPTY(&ncp->nc_list))
1530 if (ncp->nc_lockstatus & ~(NC_EXLOCK_REQ|NC_SHLOCK_REQ))
1533 spin_lock(&ncneg.spin);
1534 TAILQ_REMOVE(&ncneg.list, ncp, nc_vnode);
1536 spin_unlock(&ncneg.spin);
1538 ncp->nc_flag &= ~(NCF_WHITEOUT|NCF_ISDIR|NCF_ISSYMLINK);
1543 * The cache_nresolve() code calls this function to automatically
1544 * set a resolved cache element to unresolved if it has timed out
1545 * or if it is a negative cache hit and the mount point namecache_gen
1549 _cache_auto_unresolve_test(struct mount *mp, struct namecache *ncp)
1552 * Try to zap entries that have timed out. We have
1553 * to be careful here because locked leafs may depend
1554 * on the vnode remaining intact in a parent, so only
1555 * do this under very specific conditions.
1557 if (ncp->nc_timeout && (int)(ncp->nc_timeout - ticks) < 0 &&
1558 TAILQ_EMPTY(&ncp->nc_list)) {
1563 * If a resolved negative cache hit is invalid due to
1564 * the mount's namecache generation being bumped, zap it.
1566 if (ncp->nc_vp == NULL && VFS_NCPGEN_TEST(mp, ncp)) {
1571 * Otherwise we are good
1576 static __inline void
1577 _cache_auto_unresolve(struct mount *mp, struct namecache *ncp)
1580 * Already in an unresolved state, nothing to do.
1582 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
1583 if (_cache_auto_unresolve_test(mp, ncp))
1584 _cache_setunresolved(ncp);
1592 cache_setunresolved(struct nchandle *nch)
1594 _cache_setunresolved(nch->ncp);
1598 * Determine if we can clear NCF_ISMOUNTPT by scanning the mountlist
1599 * looking for matches. This flag tells the lookup code when it must
1600 * check for a mount linkage and also prevents the directories in question
1601 * from being deleted or renamed.
1605 cache_clrmountpt_callback(struct mount *mp, void *data)
1607 struct nchandle *nch = data;
1609 if (mp->mnt_ncmounton.ncp == nch->ncp)
1611 if (mp->mnt_ncmountpt.ncp == nch->ncp)
1617 * Clear NCF_ISMOUNTPT on nch->ncp if it is no longer associated
1618 * with a mount point.
1621 cache_clrmountpt(struct nchandle *nch)
1625 count = mountlist_scan(cache_clrmountpt_callback, nch,
1626 MNTSCAN_FORWARD|MNTSCAN_NOBUSY);
1628 nch->ncp->nc_flag &= ~NCF_ISMOUNTPT;
1632 * Invalidate portions of the namecache topology given a starting entry.
1633 * The passed ncp is set to an unresolved state and:
1635 * The passed ncp must be referencxed and locked. The routine may unlock
1636 * and relock ncp several times, and will recheck the children and loop
1637 * to catch races. When done the passed ncp will be returned with the
1638 * reference and lock intact.
1640 * CINV_DESTROY - Set a flag in the passed ncp entry indicating
1641 * that the physical underlying nodes have been
1642 * destroyed... as in deleted. For example, when
1643 * a directory is removed. This will cause record
1644 * lookups on the name to no longer be able to find
1645 * the record and tells the resolver to return failure
1646 * rather then trying to resolve through the parent.
1648 * The topology itself, including ncp->nc_name,
1651 * This only applies to the passed ncp, if CINV_CHILDREN
1652 * is specified the children are not flagged.
1654 * CINV_CHILDREN - Set all children (recursively) to an unresolved
1657 * Note that this will also have the side effect of
1658 * cleaning out any unreferenced nodes in the topology
1659 * from the leaves up as the recursion backs out.
1661 * Note that the topology for any referenced nodes remains intact, but
1662 * the nodes will be marked as having been destroyed and will be set
1663 * to an unresolved state.
1665 * It is possible for cache_inval() to race a cache_resolve(), meaning that
1666 * the namecache entry may not actually be invalidated on return if it was
1667 * revalidated while recursing down into its children. This code guarentees
1668 * that the node(s) will go through an invalidation cycle, but does not
1669 * guarentee that they will remain in an invalidated state.
1671 * Returns non-zero if a revalidation was detected during the invalidation
1672 * recursion, zero otherwise. Note that since only the original ncp is
1673 * locked the revalidation ultimately can only indicate that the original ncp
1674 * *MIGHT* no have been reresolved.
1676 * DEEP RECURSION HANDLING - If a recursive invalidation recurses deeply we
1677 * have to avoid blowing out the kernel stack. We do this by saving the
1678 * deep namecache node and aborting the recursion, then re-recursing at that
1679 * node using a depth-first algorithm in order to allow multiple deep
1680 * recursions to chain through each other, then we restart the invalidation
1685 struct namecache *resume_ncp;
1689 static int _cache_inval_internal(struct namecache *, int, struct cinvtrack *);
1693 _cache_inval(struct namecache *ncp, int flags)
1695 struct cinvtrack track;
1696 struct namecache *ncp2;
1700 track.resume_ncp = NULL;
1703 r = _cache_inval_internal(ncp, flags, &track);
1704 if (track.resume_ncp == NULL)
1707 while ((ncp2 = track.resume_ncp) != NULL) {
1708 track.resume_ncp = NULL;
1710 _cache_inval_internal(ncp2, flags & ~CINV_DESTROY,
1720 cache_inval(struct nchandle *nch, int flags)
1722 return(_cache_inval(nch->ncp, flags));
1726 * Helper for _cache_inval(). The passed ncp is refd and locked and
1727 * remains that way on return, but may be unlocked/relocked multiple
1728 * times by the routine.
1731 _cache_inval_internal(struct namecache *ncp, int flags, struct cinvtrack *track)
1733 struct namecache *nextkid;
1736 KKASSERT(_cache_lockstatus(ncp) == LK_EXCLUSIVE);
1738 _cache_setunresolved(ncp);
1739 if (flags & CINV_DESTROY) {
1740 ncp->nc_flag |= NCF_DESTROYED;
1741 ++ncp->nc_generation;
1743 while ((flags & CINV_CHILDREN) &&
1744 (nextkid = TAILQ_FIRST(&ncp->nc_list)) != NULL
1746 struct namecache *kid;
1750 _cache_hold(nextkid);
1751 if (++track->depth > MAX_RECURSION_DEPTH) {
1752 track->resume_ncp = ncp;
1756 while ((kid = nextkid) != NULL) {
1758 * Parent (ncp) must be locked for the iteration.
1761 if (kid->nc_parent != ncp) {
1763 kprintf("cache_inval_internal restartA %s\n",
1768 if ((nextkid = TAILQ_NEXT(kid, nc_entry)) != NULL)
1769 _cache_hold(nextkid);
1772 * Parent unlocked for this section to avoid
1776 if (track->resume_ncp) {
1781 if ((kid->nc_flag & NCF_UNRESOLVED) == 0 ||
1782 TAILQ_FIRST(&kid->nc_list)
1785 if (kid->nc_parent != ncp) {
1786 kprintf("cache_inval_internal "
1796 rcnt += _cache_inval_internal(kid, flags & ~CINV_DESTROY, track);
1803 _cache_drop(nextkid);
1810 * Someone could have gotten in there while ncp was unlocked,
1813 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0)
1819 * Invalidate a vnode's namecache associations. To avoid races against
1820 * the resolver we do not invalidate a node which we previously invalidated
1821 * but which was then re-resolved while we were in the invalidation loop.
1823 * Returns non-zero if any namecache entries remain after the invalidation
1826 * NOTE: Unlike the namecache topology which guarentees that ncp's will not
1827 * be ripped out of the topology while held, the vnode's v_namecache
1828 * list has no such restriction. NCP's can be ripped out of the list
1829 * at virtually any time if not locked, even if held.
1831 * In addition, the v_namecache list itself must be locked via
1832 * the vnode's spinlock.
1835 cache_inval_vp(struct vnode *vp, int flags)
1837 struct namecache *ncp;
1838 struct namecache *next;
1841 spin_lock(&vp->v_spin);
1842 ncp = TAILQ_FIRST(&vp->v_namecache);
1846 /* loop entered with ncp held and vp spin-locked */
1847 if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL)
1849 spin_unlock(&vp->v_spin);
1851 if (ncp->nc_vp != vp) {
1852 kprintf("Warning: cache_inval_vp: race-A detected on "
1853 "%s\n", ncp->nc_name);
1859 _cache_inval(ncp, flags);
1860 _cache_put(ncp); /* also releases reference */
1862 spin_lock(&vp->v_spin);
1863 if (ncp && ncp->nc_vp != vp) {
1864 spin_unlock(&vp->v_spin);
1865 kprintf("Warning: cache_inval_vp: race-B detected on "
1866 "%s\n", ncp->nc_name);
1871 spin_unlock(&vp->v_spin);
1872 return(TAILQ_FIRST(&vp->v_namecache) != NULL);
1876 * This routine is used instead of the normal cache_inval_vp() when we
1877 * are trying to recycle otherwise good vnodes.
1879 * Return 0 on success, non-zero if not all namecache records could be
1880 * disassociated from the vnode (for various reasons).
1883 cache_inval_vp_nonblock(struct vnode *vp)
1885 struct namecache *ncp;
1886 struct namecache *next;
1888 spin_lock(&vp->v_spin);
1889 ncp = TAILQ_FIRST(&vp->v_namecache);
1893 /* loop entered with ncp held */
1894 if ((next = TAILQ_NEXT(ncp, nc_vnode)) != NULL)
1896 spin_unlock(&vp->v_spin);
1897 if (_cache_lock_nonblock(ncp)) {
1903 if (ncp->nc_vp != vp) {
1904 kprintf("Warning: cache_inval_vp: race-A detected on "
1905 "%s\n", ncp->nc_name);
1911 _cache_inval(ncp, 0);
1912 _cache_put(ncp); /* also releases reference */
1914 spin_lock(&vp->v_spin);
1915 if (ncp && ncp->nc_vp != vp) {
1916 spin_unlock(&vp->v_spin);
1917 kprintf("Warning: cache_inval_vp: race-B detected on "
1918 "%s\n", ncp->nc_name);
1923 spin_unlock(&vp->v_spin);
1925 return(TAILQ_FIRST(&vp->v_namecache) != NULL);
1929 * Clears the universal directory search 'ok' flag. This flag allows
1930 * nlookup() to bypass normal vnode checks. This flag is a cached flag
1931 * so clearing it simply forces revalidation.
1934 cache_inval_wxok(struct vnode *vp)
1936 struct namecache *ncp;
1938 spin_lock(&vp->v_spin);
1939 TAILQ_FOREACH(ncp, &vp->v_namecache, nc_vnode) {
1940 if (ncp->nc_flag & NCF_WXOK)
1941 atomic_clear_short(&ncp->nc_flag, NCF_WXOK);
1943 spin_unlock(&vp->v_spin);
1947 * The source ncp has been renamed to the target ncp. Both fncp and tncp
1948 * must be locked. The target ncp is destroyed (as a normal rename-over
1949 * would destroy the target file or directory).
1951 * Because there may be references to the source ncp we cannot copy its
1952 * contents to the target. Instead the source ncp is relinked as the target
1953 * and the target ncp is removed from the namecache topology.
1956 cache_rename(struct nchandle *fnch, struct nchandle *tnch)
1958 struct namecache *fncp = fnch->ncp;
1959 struct namecache *tncp = tnch->ncp;
1960 struct namecache *tncp_par;
1961 struct nchash_head *nchpp;
1966 ++fncp->nc_generation;
1967 ++tncp->nc_generation;
1968 if (tncp->nc_nlen) {
1969 nname = kmalloc(tncp->nc_nlen + 1, M_VFSCACHE, M_WAITOK);
1970 bcopy(tncp->nc_name, nname, tncp->nc_nlen);
1971 nname[tncp->nc_nlen] = 0;
1977 * Rename fncp (unlink)
1979 _cache_unlink_parent(fncp);
1980 oname = fncp->nc_name;
1981 fncp->nc_name = nname;
1982 fncp->nc_nlen = tncp->nc_nlen;
1984 kfree(oname, M_VFSCACHE);
1986 tncp_par = tncp->nc_parent;
1987 _cache_hold(tncp_par);
1988 _cache_lock(tncp_par);
1991 * Rename fncp (relink)
1993 hash = fnv_32_buf(fncp->nc_name, fncp->nc_nlen, FNV1_32_INIT);
1994 hash = fnv_32_buf(&tncp_par, sizeof(tncp_par), hash);
1995 nchpp = NCHHASH(hash);
1997 spin_lock(&nchpp->spin);
1998 _cache_link_parent(fncp, tncp_par, nchpp);
1999 spin_unlock(&nchpp->spin);
2001 _cache_put(tncp_par);
2004 * Get rid of the overwritten tncp (unlink)
2006 _cache_unlink(tncp);
2010 * Perform actions consistent with unlinking a file. The passed-in ncp
2013 * The ncp is marked DESTROYED so it no longer shows up in searches,
2014 * and will be physically deleted when the vnode goes away.
2016 * If the related vnode has no refs then we cycle it through vget()/vput()
2017 * to (possibly if we don't have a ref race) trigger a deactivation,
2018 * allowing the VFS to trivially detect and recycle the deleted vnode
2019 * via VOP_INACTIVE().
2021 * NOTE: _cache_rename() will automatically call _cache_unlink() on the
2025 cache_unlink(struct nchandle *nch)
2027 _cache_unlink(nch->ncp);
2031 _cache_unlink(struct namecache *ncp)
2036 * Causes lookups to fail and allows another ncp with the same
2037 * name to be created under ncp->nc_parent.
2039 ncp->nc_flag |= NCF_DESTROYED;
2040 ++ncp->nc_generation;
2043 * Attempt to trigger a deactivation. Set VREF_FINALIZE to
2044 * force action on the 1->0 transition.
2046 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0 &&
2047 (vp = ncp->nc_vp) != NULL) {
2048 atomic_set_int(&vp->v_refcnt, VREF_FINALIZE);
2049 if (VREFCNT(vp) <= 0) {
2050 if (vget(vp, LK_SHARED) == 0)
2057 * Return non-zero if the nch might be associated with an open and/or mmap()'d
2058 * file. The easy solution is to just return non-zero if the vnode has refs.
2059 * Used to interlock hammer2 reclaims (VREF_FINALIZE should already be set to
2060 * force the reclaim).
2063 cache_isopen(struct nchandle *nch)
2066 struct namecache *ncp = nch->ncp;
2068 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0 &&
2069 (vp = ncp->nc_vp) != NULL &&
2078 * vget the vnode associated with the namecache entry. Resolve the namecache
2079 * entry if necessary. The passed ncp must be referenced and locked. If
2080 * the ncp is resolved it might be locked shared.
2082 * lk_type may be LK_SHARED, LK_EXCLUSIVE. A ref'd, possibly locked
2083 * (depending on the passed lk_type) will be returned in *vpp with an error
2084 * of 0, or NULL will be returned in *vpp with a non-0 error code. The
2085 * most typical error is ENOENT, meaning that the ncp represents a negative
2086 * cache hit and there is no vnode to retrieve, but other errors can occur
2089 * The vget() can race a reclaim. If this occurs we re-resolve the
2092 * There are numerous places in the kernel where vget() is called on a
2093 * vnode while one or more of its namecache entries is locked. Releasing
2094 * a vnode never deadlocks against locked namecache entries (the vnode
2095 * will not get recycled while referenced ncp's exist). This means we
2096 * can safely acquire the vnode. In fact, we MUST NOT release the ncp
2097 * lock when acquiring the vp lock or we might cause a deadlock.
2099 * NOTE: The passed-in ncp must be locked exclusively if it is initially
2100 * unresolved. If a reclaim race occurs the passed-in ncp will be
2101 * relocked exclusively before being re-resolved.
2104 cache_vget(struct nchandle *nch, struct ucred *cred,
2105 int lk_type, struct vnode **vpp)
2107 struct namecache *ncp;
2114 if (ncp->nc_flag & NCF_UNRESOLVED)
2115 error = cache_resolve(nch, cred);
2119 if (error == 0 && (vp = ncp->nc_vp) != NULL) {
2120 error = vget(vp, lk_type);
2125 * The ncp may have been locked shared, we must relock
2126 * it exclusively before we can set it to unresolved.
2128 if (error == ENOENT) {
2129 kprintf("Warning: vnode reclaim race detected "
2130 "in cache_vget on %p (%s)\n",
2134 _cache_setunresolved(ncp);
2139 * Not a reclaim race, some other error.
2141 KKASSERT(ncp->nc_vp == vp);
2144 KKASSERT(ncp->nc_vp == vp);
2145 KKASSERT((vp->v_flag & VRECLAIMED) == 0);
2148 if (error == 0 && vp == NULL)
2155 * Similar to cache_vget() but only acquires a ref on the vnode.
2157 * NOTE: The passed-in ncp must be locked exclusively if it is initially
2158 * unresolved. If a reclaim race occurs the passed-in ncp will be
2159 * relocked exclusively before being re-resolved.
2162 cache_vref(struct nchandle *nch, struct ucred *cred, struct vnode **vpp)
2164 struct namecache *ncp;
2171 if (ncp->nc_flag & NCF_UNRESOLVED)
2172 error = cache_resolve(nch, cred);
2176 if (error == 0 && (vp = ncp->nc_vp) != NULL) {
2177 error = vget(vp, LK_SHARED);
2182 if (error == ENOENT) {
2183 kprintf("Warning: vnode reclaim race detected "
2184 "in cache_vget on %p (%s)\n",
2188 _cache_setunresolved(ncp);
2193 * Not a reclaim race, some other error.
2195 KKASSERT(ncp->nc_vp == vp);
2198 KKASSERT(ncp->nc_vp == vp);
2199 KKASSERT((vp->v_flag & VRECLAIMED) == 0);
2200 /* caller does not want a lock */
2204 if (error == 0 && vp == NULL)
2211 * Return a referenced vnode representing the parent directory of
2214 * Because the caller has locked the ncp it should not be possible for
2215 * the parent ncp to go away. However, the parent can unresolve its
2216 * dvp at any time so we must be able to acquire a lock on the parent
2217 * to safely access nc_vp.
2219 * We have to leave par unlocked when vget()ing dvp to avoid a deadlock,
2220 * so use vhold()/vdrop() while holding the lock to prevent dvp from
2221 * getting destroyed.
2223 * NOTE: vhold() is allowed when dvp has 0 refs if we hold a
2224 * lock on the ncp in question..
2226 static struct vnode *
2227 cache_dvpref(struct namecache *ncp)
2229 struct namecache *par;
2233 if ((par = ncp->nc_parent) != NULL) {
2236 if ((par->nc_flag & NCF_UNRESOLVED) == 0) {
2237 if ((dvp = par->nc_vp) != NULL)
2242 if (vget(dvp, LK_SHARED) == 0) {
2245 /* return refd, unlocked dvp */
2257 * Convert a directory vnode to a namecache record without any other
2258 * knowledge of the topology. This ONLY works with directory vnodes and
2259 * is ONLY used by the NFS server. dvp must be refd but unlocked, and the
2260 * returned ncp (if not NULL) will be held and unlocked.
2262 * If 'makeit' is 0 and dvp has no existing namecache record, NULL is returned.
2263 * If 'makeit' is 1 we attempt to track-down and create the namecache topology
2264 * for dvp. This will fail only if the directory has been deleted out from
2267 * Callers must always check for a NULL return no matter the value of 'makeit'.
2269 * To avoid underflowing the kernel stack each recursive call increments
2270 * the makeit variable.
2273 static int cache_inefficient_scan(struct nchandle *nch, struct ucred *cred,
2274 struct vnode *dvp, char *fakename);
2275 static int cache_fromdvp_try(struct vnode *dvp, struct ucred *cred,
2276 struct vnode **saved_dvp);
2279 cache_fromdvp(struct vnode *dvp, struct ucred *cred, int makeit,
2280 struct nchandle *nch)
2282 struct vnode *saved_dvp;
2288 nch->mount = dvp->v_mount;
2293 * Handle the makeit == 0 degenerate case
2296 spin_lock_shared(&dvp->v_spin);
2297 nch->ncp = TAILQ_FIRST(&dvp->v_namecache);
2300 spin_unlock_shared(&dvp->v_spin);
2304 * Loop until resolution, inside code will break out on error.
2308 * Break out if we successfully acquire a working ncp.
2310 spin_lock_shared(&dvp->v_spin);
2311 nch->ncp = TAILQ_FIRST(&dvp->v_namecache);
2314 spin_unlock_shared(&dvp->v_spin);
2317 spin_unlock_shared(&dvp->v_spin);
2320 * If dvp is the root of its filesystem it should already
2321 * have a namecache pointer associated with it as a side
2322 * effect of the mount, but it may have been disassociated.
2324 if (dvp->v_flag & VROOT) {
2325 nch->ncp = _cache_get(nch->mount->mnt_ncmountpt.ncp);
2326 error = cache_resolve_mp(nch->mount);
2327 _cache_put(nch->ncp);
2329 kprintf("cache_fromdvp: resolve root of mount %p error %d",
2330 dvp->v_mount, error);
2334 kprintf(" failed\n");
2339 kprintf(" succeeded\n");
2344 * If we are recursed too deeply resort to an O(n^2)
2345 * algorithm to resolve the namecache topology. The
2346 * resolved pvp is left referenced in saved_dvp to
2347 * prevent the tree from being destroyed while we loop.
2350 error = cache_fromdvp_try(dvp, cred, &saved_dvp);
2352 kprintf("lookupdotdot(longpath) failed %d "
2353 "dvp %p\n", error, dvp);
2361 * Get the parent directory and resolve its ncp.
2364 kfree(fakename, M_TEMP);
2367 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred,
2370 kprintf("lookupdotdot failed %d dvp %p\n", error, dvp);
2376 * Reuse makeit as a recursion depth counter. On success
2377 * nch will be fully referenced.
2379 cache_fromdvp(pvp, cred, makeit + 1, nch);
2381 if (nch->ncp == NULL)
2385 * Do an inefficient scan of pvp (embodied by ncp) to look
2386 * for dvp. This will create a namecache record for dvp on
2387 * success. We loop up to recheck on success.
2389 * ncp and dvp are both held but not locked.
2391 error = cache_inefficient_scan(nch, cred, dvp, fakename);
2393 kprintf("cache_fromdvp: scan %p (%s) failed on dvp=%p\n",
2394 pvp, nch->ncp->nc_name, dvp);
2396 /* nch was NULLed out, reload mount */
2397 nch->mount = dvp->v_mount;
2401 kprintf("cache_fromdvp: scan %p (%s) succeeded\n",
2402 pvp, nch->ncp->nc_name);
2405 /* nch was NULLed out, reload mount */
2406 nch->mount = dvp->v_mount;
2410 * If nch->ncp is non-NULL it will have been held already.
2413 kfree(fakename, M_TEMP);
2422 * Go up the chain of parent directories until we find something
2423 * we can resolve into the namecache. This is very inefficient.
2427 cache_fromdvp_try(struct vnode *dvp, struct ucred *cred,
2428 struct vnode **saved_dvp)
2430 struct nchandle nch;
2433 static time_t last_fromdvp_report;
2437 * Loop getting the parent directory vnode until we get something we
2438 * can resolve in the namecache.
2441 nch.mount = dvp->v_mount;
2447 kfree(fakename, M_TEMP);
2450 error = vop_nlookupdotdot(*dvp->v_ops, dvp, &pvp, cred,
2457 spin_lock_shared(&pvp->v_spin);
2458 if ((nch.ncp = TAILQ_FIRST(&pvp->v_namecache)) != NULL) {
2459 _cache_hold(nch.ncp);
2460 spin_unlock_shared(&pvp->v_spin);
2464 spin_unlock_shared(&pvp->v_spin);
2465 if (pvp->v_flag & VROOT) {
2466 nch.ncp = _cache_get(pvp->v_mount->mnt_ncmountpt.ncp);
2467 error = cache_resolve_mp(nch.mount);
2468 _cache_unlock(nch.ncp);
2471 _cache_drop(nch.ncp);
2481 if (last_fromdvp_report != time_uptime) {
2482 last_fromdvp_report = time_uptime;
2483 kprintf("Warning: extremely inefficient path "
2484 "resolution on %s\n",
2487 error = cache_inefficient_scan(&nch, cred, dvp, fakename);
2490 * Hopefully dvp now has a namecache record associated with
2491 * it. Leave it referenced to prevent the kernel from
2492 * recycling the vnode. Otherwise extremely long directory
2493 * paths could result in endless recycling.
2498 _cache_drop(nch.ncp);
2501 kfree(fakename, M_TEMP);
2506 * Do an inefficient scan of the directory represented by ncp looking for
2507 * the directory vnode dvp. ncp must be held but not locked on entry and
2508 * will be held on return. dvp must be refd but not locked on entry and
2509 * will remain refd on return.
2511 * Why do this at all? Well, due to its stateless nature the NFS server
2512 * converts file handles directly to vnodes without necessarily going through
2513 * the namecache ops that would otherwise create the namecache topology
2514 * leading to the vnode. We could either (1) Change the namecache algorithms
2515 * to allow disconnect namecache records that are re-merged opportunistically,
2516 * or (2) Make the NFS server backtrack and scan to recover a connected
2517 * namecache topology in order to then be able to issue new API lookups.
2519 * It turns out that (1) is a huge mess. It takes a nice clean set of
2520 * namecache algorithms and introduces a lot of complication in every subsystem
2521 * that calls into the namecache to deal with the re-merge case, especially
2522 * since we are using the namecache to placehold negative lookups and the
2523 * vnode might not be immediately assigned. (2) is certainly far less
2524 * efficient then (1), but since we are only talking about directories here
2525 * (which are likely to remain cached), the case does not actually run all
2526 * that often and has the supreme advantage of not polluting the namecache
2529 * If a fakename is supplied just construct a namecache entry using the
2533 cache_inefficient_scan(struct nchandle *nch, struct ucred *cred,
2534 struct vnode *dvp, char *fakename)
2536 struct nlcomponent nlc;
2537 struct nchandle rncp;
2549 vat.va_blocksize = 0;
2550 if ((error = VOP_GETATTR(dvp, &vat)) != 0)
2553 error = cache_vref(nch, cred, &pvp);
2558 kprintf("inefficient_scan of (%p,%s): directory iosize %ld "
2559 "vattr fileid = %lld\n",
2560 nch->ncp, nch->ncp->nc_name,
2562 (long long)vat.va_fileid);
2566 * Use the supplied fakename if not NULL. Fake names are typically
2567 * not in the actual filesystem hierarchy. This is used by HAMMER
2568 * to glue @@timestamp recursions together.
2571 nlc.nlc_nameptr = fakename;
2572 nlc.nlc_namelen = strlen(fakename);
2573 rncp = cache_nlookup(nch, &nlc);
2577 if ((blksize = vat.va_blocksize) == 0)
2578 blksize = DEV_BSIZE;
2579 rbuf = kmalloc(blksize, M_TEMP, M_WAITOK);
2585 iov.iov_base = rbuf;
2586 iov.iov_len = blksize;
2589 uio.uio_resid = blksize;
2590 uio.uio_segflg = UIO_SYSSPACE;
2591 uio.uio_rw = UIO_READ;
2592 uio.uio_td = curthread;
2594 if (ncvp_debug >= 2)
2595 kprintf("cache_inefficient_scan: readdir @ %08x\n", (int)uio.uio_offset);
2596 error = VOP_READDIR(pvp, &uio, cred, &eofflag, NULL, NULL);
2598 den = (struct dirent *)rbuf;
2599 bytes = blksize - uio.uio_resid;
2602 if (ncvp_debug >= 2) {
2603 kprintf("cache_inefficient_scan: %*.*s\n",
2604 den->d_namlen, den->d_namlen,
2607 if (den->d_type != DT_WHT &&
2608 den->d_ino == vat.va_fileid) {
2610 kprintf("cache_inefficient_scan: "
2611 "MATCHED inode %lld path %s/%*.*s\n",
2612 (long long)vat.va_fileid,
2614 den->d_namlen, den->d_namlen,
2617 nlc.nlc_nameptr = den->d_name;
2618 nlc.nlc_namelen = den->d_namlen;
2619 rncp = cache_nlookup(nch, &nlc);
2620 KKASSERT(rncp.ncp != NULL);
2623 bytes -= _DIRENT_DIRSIZ(den);
2624 den = _DIRENT_NEXT(den);
2626 if (rncp.ncp == NULL && eofflag == 0 && uio.uio_resid != blksize)
2629 kfree(rbuf, M_TEMP);
2633 if (rncp.ncp->nc_flag & NCF_UNRESOLVED) {
2634 _cache_setvp(rncp.mount, rncp.ncp, dvp);
2635 if (ncvp_debug >= 2) {
2636 kprintf("cache_inefficient_scan: setvp %s/%s = %p\n",
2637 nch->ncp->nc_name, rncp.ncp->nc_name, dvp);
2640 if (ncvp_debug >= 2) {
2641 kprintf("cache_inefficient_scan: setvp %s/%s already set %p/%p\n",
2642 nch->ncp->nc_name, rncp.ncp->nc_name, dvp,
2646 if (rncp.ncp->nc_vp == NULL)
2647 error = rncp.ncp->nc_error;
2649 * Release rncp after a successful nlookup. rncp was fully
2654 kprintf("cache_inefficient_scan: dvp %p NOT FOUND in %s\n",
2655 dvp, nch->ncp->nc_name);
2662 * Zap a namecache entry. The ncp is unconditionally set to an unresolved
2663 * state, which disassociates it from its vnode or ncneg.list.
2665 * Then, if there are no additional references to the ncp and no children,
2666 * the ncp is removed from the topology and destroyed.
2668 * References and/or children may exist if the ncp is in the middle of the
2669 * topology, preventing the ncp from being destroyed.
2671 * This function must be called with the ncp held and locked and will unlock
2672 * and drop it during zapping.
2674 * If nonblock is non-zero and the parent ncp cannot be locked we give up.
2675 * This case can occur in the cache_drop() path.
2677 * This function may returned a held (but NOT locked) parent node which the
2678 * caller must drop. We do this so _cache_drop() can loop, to avoid
2679 * blowing out the kernel stack.
2681 * WARNING! For MPSAFE operation this routine must acquire up to three
2682 * spin locks to be able to safely test nc_refs. Lock order is
2685 * hash spinlock if on hash list
2686 * parent spinlock if child of parent
2687 * (the ncp is unresolved so there is no vnode association)
2689 static struct namecache *
2690 cache_zap(struct namecache *ncp, int nonblock)
2692 struct namecache *par;
2693 struct vnode *dropvp;
2694 struct nchash_head *nchpp;
2698 * Disassociate the vnode or negative cache ref and set NCF_UNRESOLVED.
2700 _cache_setunresolved(ncp);
2703 * Try to scrap the entry and possibly tail-recurse on its parent.
2704 * We only scrap unref'd (other then our ref) unresolved entries,
2705 * we do not scrap 'live' entries.
2707 * Note that once the spinlocks are acquired if nc_refs == 1 no
2708 * other references are possible. If it isn't, however, we have
2709 * to decrement but also be sure to avoid a 1->0 transition.
2711 KKASSERT(ncp->nc_flag & NCF_UNRESOLVED);
2712 KKASSERT(ncp->nc_refs > 0);
2715 * Acquire locks. Note that the parent can't go away while we hold
2719 if ((par = ncp->nc_parent) != NULL) {
2722 if (_cache_lock_nonblock(par) == 0)
2724 refs = ncp->nc_refs;
2725 ncp->nc_flag |= NCF_DEFEREDZAP;
2726 ++numdefered; /* MP race ok */
2727 if (atomic_cmpset_int(&ncp->nc_refs,
2739 nchpp = ncp->nc_head;
2740 spin_lock(&nchpp->spin);
2744 * At this point if we find refs == 1 it should not be possible for
2745 * anyone else to have access to the ncp. We are holding the only
2746 * possible access point left (nchpp) spin-locked.
2748 * If someone other then us has a ref or we have children
2749 * we cannot zap the entry. The 1->0 transition and any
2750 * further list operation is protected by the spinlocks
2751 * we have acquired but other transitions are not.
2754 refs = ncp->nc_refs;
2756 if (refs == 1 && TAILQ_EMPTY(&ncp->nc_list))
2758 if (atomic_cmpset_int(&ncp->nc_refs, refs, refs - 1)) {
2760 spin_unlock(&nchpp->spin);
2770 * We are the only ref and with the spinlocks held no further
2771 * refs can be acquired by others.
2773 * Remove us from the hash list and parent list. We have to
2774 * drop a ref on the parent's vp if the parent's list becomes
2779 KKASSERT(nchpp == ncp->nc_head);
2780 LIST_REMOVE(ncp, nc_hash);
2781 TAILQ_REMOVE(&par->nc_list, ncp, nc_entry);
2782 if (par->nc_vp && TAILQ_EMPTY(&par->nc_list))
2783 dropvp = par->nc_vp;
2784 ncp->nc_head = NULL;
2785 ncp->nc_parent = NULL;
2786 spin_unlock(&nchpp->spin);
2789 KKASSERT(ncp->nc_head == NULL);
2793 * ncp should not have picked up any refs. Physically
2796 if (ncp->nc_refs != 1) {
2797 int save_refs = ncp->nc_refs;
2799 panic("cache_zap: %p bad refs %d (%d)\n",
2800 ncp, save_refs, atomic_fetchadd_int(&ncp->nc_refs, 0));
2802 KKASSERT(ncp->nc_refs == 1);
2803 /* _cache_unlock(ncp) not required */
2804 ncp->nc_refs = -1; /* safety */
2806 kfree(ncp->nc_name, M_VFSCACHE);
2807 kfree(ncp, M_VFSCACHE);
2810 * Delayed drop (we had to release our spinlocks)
2812 * The refed parent (if not NULL) must be dropped. The
2813 * caller is responsible for looping.
2821 * Clean up dangling negative cache and defered-drop entries in the
2824 * This routine is called in the critical path and also called from
2825 * vnlru(). When called from vnlru we use a lower limit to try to
2826 * deal with the negative cache before the critical path has to start
2829 typedef enum { CHI_LOW, CHI_HIGH } cache_hs_t;
2831 static cache_hs_t neg_cache_hysteresis_state[2] = { CHI_LOW, CHI_LOW };
2832 static cache_hs_t pos_cache_hysteresis_state[2] = { CHI_LOW, CHI_LOW };
2835 cache_hysteresis(int critpath)
2838 int neglimit = maxvnodes / ncnegfactor;
2839 int xnumcache = numcache;
2842 neglimit = neglimit * 8 / 10;
2845 * Don't cache too many negative hits. We use hysteresis to reduce
2846 * the impact on the critical path.
2848 switch(neg_cache_hysteresis_state[critpath]) {
2850 if (numneg > MINNEG && numneg > neglimit) {
2852 _cache_cleanneg(ncnegflush);
2854 _cache_cleanneg(ncnegflush +
2856 neg_cache_hysteresis_state[critpath] = CHI_HIGH;
2860 if (numneg > MINNEG * 9 / 10 &&
2861 numneg * 9 / 10 > neglimit
2864 _cache_cleanneg(ncnegflush);
2866 _cache_cleanneg(ncnegflush +
2867 numneg * 9 / 10 - neglimit);
2869 neg_cache_hysteresis_state[critpath] = CHI_LOW;
2875 * Don't cache too many positive hits. We use hysteresis to reduce
2876 * the impact on the critical path.
2878 * Excessive positive hits can accumulate due to large numbers of
2879 * hardlinks (the vnode cache will not prevent hl ncps from growing
2882 if ((poslimit = ncposlimit) == 0)
2883 poslimit = maxvnodes * 2;
2885 poslimit = poslimit * 8 / 10;
2887 switch(pos_cache_hysteresis_state[critpath]) {
2889 if (xnumcache > poslimit && xnumcache > MINPOS) {
2891 _cache_cleanpos(ncposflush);
2893 _cache_cleanpos(ncposflush +
2894 xnumcache - poslimit);
2895 pos_cache_hysteresis_state[critpath] = CHI_HIGH;
2899 if (xnumcache > poslimit * 5 / 6 && xnumcache > MINPOS) {
2901 _cache_cleanpos(ncposflush);
2903 _cache_cleanpos(ncposflush +
2904 xnumcache - poslimit * 5 / 6);
2906 pos_cache_hysteresis_state[critpath] = CHI_LOW;
2912 * Clean out dangling defered-zap ncps which could not
2913 * be cleanly dropped if too many build up. Note
2914 * that numdefered is not an exact number as such ncps
2915 * can be reused and the counter is not handled in a MP
2916 * safe manner by design.
2918 if (numdefered > neglimit) {
2919 _cache_cleandefered();
2924 * NEW NAMECACHE LOOKUP API
2926 * Lookup an entry in the namecache. The passed par_nch must be referenced
2927 * and unlocked. A referenced and locked nchandle with a non-NULL nch.ncp
2928 * is ALWAYS returned, eve if the supplied component is illegal.
2930 * The resulting namecache entry should be returned to the system with
2931 * cache_put() or cache_unlock() + cache_drop().
2933 * namecache locks are recursive but care must be taken to avoid lock order
2934 * reversals (hence why the passed par_nch must be unlocked). Locking
2935 * rules are to order for parent traversals, not for child traversals.
2937 * Nobody else will be able to manipulate the associated namespace (e.g.
2938 * create, delete, rename, rename-target) until the caller unlocks the
2941 * The returned entry will be in one of three states: positive hit (non-null
2942 * vnode), negative hit (null vnode), or unresolved (NCF_UNRESOLVED is set).
2943 * Unresolved entries must be resolved through the filesystem to associate the
2944 * vnode and/or determine whether a positive or negative hit has occured.
2946 * It is not necessary to lock a directory in order to lock namespace under
2947 * that directory. In fact, it is explicitly not allowed to do that. A
2948 * directory is typically only locked when being created, renamed, or
2951 * The directory (par) may be unresolved, in which case any returned child
2952 * will likely also be marked unresolved. Likely but not guarenteed. Since
2953 * the filesystem lookup requires a resolved directory vnode the caller is
2954 * responsible for resolving the namecache chain top-down. This API
2955 * specifically allows whole chains to be created in an unresolved state.
2958 cache_nlookup(struct nchandle *par_nch, struct nlcomponent *nlc)
2960 struct nchandle nch;
2961 struct namecache *ncp;
2962 struct namecache *new_ncp;
2963 struct nchash_head *nchpp;
2970 mp = par_nch->mount;
2974 * This is a good time to call it, no ncp's are locked by
2977 cache_hysteresis(1);
2980 * Try to locate an existing entry
2982 hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT);
2983 hash = fnv_32_buf(&par_nch->ncp, sizeof(par_nch->ncp), hash);
2985 nchpp = NCHHASH(hash);
2988 spin_lock(&nchpp->spin);
2990 spin_lock_shared(&nchpp->spin);
2992 LIST_FOREACH(ncp, &nchpp->list, nc_hash) {
2994 * Break out if we find a matching entry. Note that
2995 * UNRESOLVED entries may match, but DESTROYED entries
2998 if (ncp->nc_parent == par_nch->ncp &&
2999 ncp->nc_nlen == nlc->nlc_namelen &&
3000 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 &&
3001 (ncp->nc_flag & NCF_DESTROYED) == 0
3005 spin_unlock(&nchpp->spin);
3007 spin_unlock_shared(&nchpp->spin);
3009 _cache_unlock(par_nch->ncp);
3012 if (_cache_lock_special(ncp) == 0) {
3014 * Successfully locked but we must re-test
3015 * conditions that might have changed since
3016 * we did not have the lock before.
3018 if (ncp->nc_parent != par_nch->ncp ||
3019 ncp->nc_nlen != nlc->nlc_namelen ||
3020 bcmp(ncp->nc_name, nlc->nlc_nameptr,
3022 (ncp->nc_flag & NCF_DESTROYED)) {
3026 _cache_auto_unresolve(mp, ncp);
3028 _cache_free(new_ncp);
3031 _cache_get(ncp); /* cycle the lock to block */
3039 * We failed to locate an entry, create a new entry and add it to
3040 * the cache. The parent ncp must also be locked so we
3043 * We have to relookup after possibly blocking in kmalloc or
3044 * when locking par_nch.
3046 * NOTE: nlc_namelen can be 0 and nlc_nameptr NULL as a special
3047 * mount case, in which case nc_name will be NULL.
3049 if (new_ncp == NULL) {
3050 spin_unlock_shared(&nchpp->spin);
3051 new_ncp = cache_alloc(nlc->nlc_namelen);
3052 if (nlc->nlc_namelen) {
3053 bcopy(nlc->nlc_nameptr, new_ncp->nc_name,
3055 new_ncp->nc_name[nlc->nlc_namelen] = 0;
3061 * NOTE! The spinlock is held exclusively here because new_ncp
3064 if (par_locked == 0) {
3065 spin_unlock(&nchpp->spin);
3066 _cache_lock(par_nch->ncp);
3072 * WARNING! We still hold the spinlock. We have to set the hash
3073 * table entry atomically.
3076 _cache_link_parent(ncp, par_nch->ncp, nchpp);
3077 spin_unlock(&nchpp->spin);
3078 _cache_unlock(par_nch->ncp);
3079 /* par_locked = 0 - not used */
3082 * stats and namecache size management
3084 if (ncp->nc_flag & NCF_UNRESOLVED)
3085 ++gd->gd_nchstats->ncs_miss;
3086 else if (ncp->nc_vp)
3087 ++gd->gd_nchstats->ncs_goodhits;
3089 ++gd->gd_nchstats->ncs_neghits;
3092 _cache_mntref(nch.mount);
3098 * Attempt to lookup a namecache entry and return with a shared namecache
3102 cache_nlookup_maybe_shared(struct nchandle *par_nch, struct nlcomponent *nlc,
3103 int excl, struct nchandle *res_nch)
3105 struct namecache *ncp;
3106 struct nchash_head *nchpp;
3112 * If exclusive requested or shared namecache locks are disabled,
3115 if (ncp_shared_lock_disable || excl)
3116 return(EWOULDBLOCK);
3119 mp = par_nch->mount;
3122 * This is a good time to call it, no ncp's are locked by
3125 cache_hysteresis(1);
3128 * Try to locate an existing entry
3130 hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT);
3131 hash = fnv_32_buf(&par_nch->ncp, sizeof(par_nch->ncp), hash);
3132 nchpp = NCHHASH(hash);
3134 spin_lock_shared(&nchpp->spin);
3136 LIST_FOREACH(ncp, &nchpp->list, nc_hash) {
3138 * Break out if we find a matching entry. Note that
3139 * UNRESOLVED entries may match, but DESTROYED entries
3142 if (ncp->nc_parent == par_nch->ncp &&
3143 ncp->nc_nlen == nlc->nlc_namelen &&
3144 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 &&
3145 (ncp->nc_flag & NCF_DESTROYED) == 0
3148 spin_unlock_shared(&nchpp->spin);
3149 if (_cache_lock_shared_special(ncp) == 0) {
3150 if (ncp->nc_parent == par_nch->ncp &&
3151 ncp->nc_nlen == nlc->nlc_namelen &&
3152 bcmp(ncp->nc_name, nlc->nlc_nameptr,
3153 ncp->nc_nlen) == 0 &&
3154 (ncp->nc_flag & NCF_DESTROYED) == 0 &&
3155 (ncp->nc_flag & NCF_UNRESOLVED) == 0 &&
3156 _cache_auto_unresolve_test(mp, ncp) == 0) {
3162 spin_lock_shared(&nchpp->spin);
3170 spin_unlock_shared(&nchpp->spin);
3171 return(EWOULDBLOCK);
3176 * Note that nc_error might be non-zero (e.g ENOENT).
3179 res_nch->mount = mp;
3181 ++gd->gd_nchstats->ncs_goodhits;
3182 _cache_mntref(res_nch->mount);
3184 KKASSERT(ncp->nc_error != EWOULDBLOCK);
3185 return(ncp->nc_error);
3189 * This is a non-blocking verison of cache_nlookup() used by
3190 * nfs_readdirplusrpc_uio(). It can fail for any reason and
3191 * will return nch.ncp == NULL in that case.
3194 cache_nlookup_nonblock(struct nchandle *par_nch, struct nlcomponent *nlc)
3196 struct nchandle nch;
3197 struct namecache *ncp;
3198 struct namecache *new_ncp;
3199 struct nchash_head *nchpp;
3206 mp = par_nch->mount;
3210 * Try to locate an existing entry
3212 hash = fnv_32_buf(nlc->nlc_nameptr, nlc->nlc_namelen, FNV1_32_INIT);
3213 hash = fnv_32_buf(&par_nch->ncp, sizeof(par_nch->ncp), hash);
3215 nchpp = NCHHASH(hash);
3217 spin_lock(&nchpp->spin);
3218 LIST_FOREACH(ncp, &nchpp->list, nc_hash) {
3220 * Break out if we find a matching entry. Note that
3221 * UNRESOLVED entries may match, but DESTROYED entries
3224 if (ncp->nc_parent == par_nch->ncp &&
3225 ncp->nc_nlen == nlc->nlc_namelen &&
3226 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) == 0 &&
3227 (ncp->nc_flag & NCF_DESTROYED) == 0
3230 spin_unlock(&nchpp->spin);
3232 _cache_unlock(par_nch->ncp);
3235 if (_cache_lock_special(ncp) == 0) {
3236 if (ncp->nc_parent != par_nch->ncp ||
3237 ncp->nc_nlen != nlc->nlc_namelen ||
3238 bcmp(ncp->nc_name, nlc->nlc_nameptr, ncp->nc_nlen) ||
3239 (ncp->nc_flag & NCF_DESTROYED)) {
3240 kprintf("cache_lookup_nonblock: "
3241 "ncp-race %p %*.*s\n",
3250 _cache_auto_unresolve(mp, ncp);
3252 _cache_free(new_ncp);
3263 * We failed to locate an entry, create a new entry and add it to
3264 * the cache. The parent ncp must also be locked so we
3267 * We have to relookup after possibly blocking in kmalloc or
3268 * when locking par_nch.
3270 * NOTE: nlc_namelen can be 0 and nlc_nameptr NULL as a special
3271 * mount case, in which case nc_name will be NULL.
3273 if (new_ncp == NULL) {
3274 spin_unlock(&nchpp->spin);
3275 new_ncp = cache_alloc(nlc->nlc_namelen);
3276 if (nlc->nlc_namelen) {
3277 bcopy(nlc->nlc_nameptr, new_ncp->nc_name,
3279 new_ncp->nc_name[nlc->nlc_namelen] = 0;
3283 if (par_locked == 0) {
3284 spin_unlock(&nchpp->spin);
3285 if (_cache_lock_nonblock(par_nch->ncp) == 0) {
3293 * WARNING! We still hold the spinlock. We have to set the hash
3294 * table entry atomically.
3297 _cache_link_parent(ncp, par_nch->ncp, nchpp);
3298 spin_unlock(&nchpp->spin);
3299 _cache_unlock(par_nch->ncp);
3300 /* par_locked = 0 - not used */
3303 * stats and namecache size management
3305 if (ncp->nc_flag & NCF_UNRESOLVED)
3306 ++gd->gd_nchstats->ncs_miss;
3307 else if (ncp->nc_vp)
3308 ++gd->gd_nchstats->ncs_goodhits;
3310 ++gd->gd_nchstats->ncs_neghits;
3313 _cache_mntref(nch.mount);
3318 _cache_free(new_ncp);
3327 * The namecache entry is marked as being used as a mount point.
3328 * Locate the mount if it is visible to the caller. The DragonFly
3329 * mount system allows arbitrary loops in the topology and disentangles
3330 * those loops by matching against (mp, ncp) rather than just (ncp).
3331 * This means any given ncp can dive any number of mounts, depending
3332 * on the relative mount (e.g. nullfs) the caller is at in the topology.
3334 * We use a very simple frontend cache to reduce SMP conflicts,
3335 * which we have to do because the mountlist scan needs an exclusive
3336 * lock around its ripout info list. Not to mention that there might
3337 * be a lot of mounts.
3339 struct findmount_info {
3340 struct mount *result;
3341 struct mount *nch_mount;
3342 struct namecache *nch_ncp;
3345 #define MNTCACHE_PRIME 66555444443333333ULL
3348 struct ncmount_cache *
3349 ncmount_cache_lookup(struct mount *mp, struct namecache *ncp)
3353 hash = (uintptr_t)mp + ((uintptr_t)mp >> 18);
3354 hash %= MNTCACHE_PRIME;
3355 hash ^= (uintptr_t)ncp + ((uintptr_t)ncp >> 18);
3356 hash %= MNTCACHE_PRIME;
3357 hash = hash % NCMOUNT_NUMCACHE;
3359 return (&ncmount_cache[hash]);
3364 cache_findmount_callback(struct mount *mp, void *data)
3366 struct findmount_info *info = data;
3369 * Check the mount's mounted-on point against the passed nch.
3371 if (mp->mnt_ncmounton.mount == info->nch_mount &&
3372 mp->mnt_ncmounton.ncp == info->nch_ncp
3382 cache_findmount(struct nchandle *nch)
3384 struct findmount_info info;
3385 struct ncmount_cache *ncc;
3391 if (ncmount_cache_enable == 0) {
3395 ncc = ncmount_cache_lookup(nch->mount, nch->ncp);
3396 if (ncc->ncp == nch->ncp) {
3397 spin_lock_shared(&ncc->spin);
3398 if (ncc->isneg == 0 &&
3399 ncc->ncp == nch->ncp && (mp = ncc->mp) != NULL) {
3400 if (mp->mnt_ncmounton.mount == nch->mount &&
3401 mp->mnt_ncmounton.ncp == nch->ncp) {
3403 * Cache hit (positive)
3406 spin_unlock_shared(&ncc->spin);
3409 /* else cache miss */
3412 ncc->ncp == nch->ncp && ncc->mp == nch->mount) {
3414 * Cache hit (negative)
3416 spin_unlock_shared(&ncc->spin);
3419 spin_unlock_shared(&ncc->spin);
3427 info.nch_mount = nch->mount;
3428 info.nch_ncp = nch->ncp;
3429 mountlist_scan(cache_findmount_callback, &info,
3430 MNTSCAN_FORWARD|MNTSCAN_NOBUSY);
3435 * Negative lookups: We cache the originating {ncp,mp}. (mp) is
3436 * only used for pointer comparisons and is not
3437 * referenced (otherwise there would be dangling
3440 * Positive lookups: We cache the originating {ncp} and the target
3441 * (mp). (mp) is referenced.
3443 * Indeterminant: If the match is undergoing an unmount we do
3444 * not cache it to avoid racing cache_unmounting(),
3445 * but still return the match.
3448 spin_lock(&ncc->spin);
3449 if (info.result == NULL) {
3450 if (ncc->isneg == 0 && ncc->mp)
3451 _cache_mntrel(ncc->mp);
3452 ncc->ncp = nch->ncp;
3453 ncc->mp = nch->mount;
3455 spin_unlock(&ncc->spin);
3456 } else if ((info.result->mnt_kern_flag & MNTK_UNMOUNT) == 0) {
3457 if (ncc->isneg == 0 && ncc->mp)
3458 _cache_mntrel(ncc->mp);
3459 _cache_mntref(info.result);
3460 ncc->ncp = nch->ncp;
3461 ncc->mp = info.result;
3463 spin_unlock(&ncc->spin);
3465 spin_unlock(&ncc->spin);
3468 return(info.result);
3472 cache_dropmount(struct mount *mp)
3478 cache_ismounting(struct mount *mp)
3480 struct nchandle *nch = &mp->mnt_ncmounton;
3481 struct ncmount_cache *ncc;
3483 ncc = ncmount_cache_lookup(nch->mount, nch->ncp);
3485 ncc->ncp == nch->ncp && ncc->mp == nch->mount) {
3486 spin_lock(&ncc->spin);
3488 ncc->ncp == nch->ncp && ncc->mp == nch->mount) {
3492 spin_unlock(&ncc->spin);
3497 cache_unmounting(struct mount *mp)
3499 struct nchandle *nch = &mp->mnt_ncmounton;
3500 struct ncmount_cache *ncc;
3502 ncc = ncmount_cache_lookup(nch->mount, nch->ncp);
3503 if (ncc->isneg == 0 &&
3504 ncc->ncp == nch->ncp && ncc->mp == mp) {
3505 spin_lock(&ncc->spin);
3506 if (ncc->isneg == 0 &&
3507 ncc->ncp == nch->ncp && ncc->mp == mp) {
3512 spin_unlock(&ncc->spin);
3517 * Resolve an unresolved namecache entry, generally by looking it up.
3518 * The passed ncp must be locked and refd.
3520 * Theoretically since a vnode cannot be recycled while held, and since
3521 * the nc_parent chain holds its vnode as long as children exist, the
3522 * direct parent of the cache entry we are trying to resolve should
3523 * have a valid vnode. If not then generate an error that we can
3524 * determine is related to a resolver bug.
3526 * However, if a vnode was in the middle of a recyclement when the NCP
3527 * got locked, ncp->nc_vp might point to a vnode that is about to become
3528 * invalid. cache_resolve() handles this case by unresolving the entry
3529 * and then re-resolving it.
3531 * Note that successful resolution does not necessarily return an error
3532 * code of 0. If the ncp resolves to a negative cache hit then ENOENT
3536 cache_resolve(struct nchandle *nch, struct ucred *cred)
3538 struct namecache *par_tmp;
3539 struct namecache *par;
3540 struct namecache *ncp;
3541 struct nchandle nctmp;
3548 KKASSERT(_cache_lockstatus(ncp) == LK_EXCLUSIVE);
3551 * If the ncp is already resolved we have nothing to do. However,
3552 * we do want to guarentee that a usable vnode is returned when
3553 * a vnode is present, so make sure it hasn't been reclaimed.
3555 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
3556 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
3557 _cache_setunresolved(ncp);
3558 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0)
3559 return (ncp->nc_error);
3563 * If the ncp was destroyed it will never resolve again. This
3564 * can basically only happen when someone is chdir'd into an
3565 * empty directory which is then rmdir'd. We want to catch this
3566 * here and not dive the VFS because the VFS might actually
3567 * have a way to re-resolve the disconnected ncp, which will
3568 * result in inconsistencies in the cdir/nch for proc->p_fd.
3570 if (ncp->nc_flag & NCF_DESTROYED)
3574 * Mount points need special handling because the parent does not
3575 * belong to the same filesystem as the ncp.
3577 if (ncp == mp->mnt_ncmountpt.ncp)
3578 return (cache_resolve_mp(mp));
3581 * We expect an unbroken chain of ncps to at least the mount point,
3582 * and even all the way to root (but this code doesn't have to go
3583 * past the mount point).
3585 if (ncp->nc_parent == NULL) {
3586 kprintf("EXDEV case 1 %p %*.*s\n", ncp,
3587 ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name);
3588 ncp->nc_error = EXDEV;
3589 return(ncp->nc_error);
3593 * The vp's of the parent directories in the chain are held via vhold()
3594 * due to the existance of the child, and should not disappear.
3595 * However, there are cases where they can disappear:
3597 * - due to filesystem I/O errors.
3598 * - due to NFS being stupid about tracking the namespace and
3599 * destroys the namespace for entire directories quite often.
3600 * - due to forced unmounts.
3601 * - due to an rmdir (parent will be marked DESTROYED)
3603 * When this occurs we have to track the chain backwards and resolve
3604 * it, looping until the resolver catches up to the current node. We
3605 * could recurse here but we might run ourselves out of kernel stack
3606 * so we do it in a more painful manner. This situation really should
3607 * not occur all that often, or if it does not have to go back too
3608 * many nodes to resolve the ncp.
3610 while ((dvp = cache_dvpref(ncp)) == NULL) {
3612 * This case can occur if a process is CD'd into a
3613 * directory which is then rmdir'd. If the parent is marked
3614 * destroyed there is no point trying to resolve it.
3616 if (ncp->nc_parent->nc_flag & NCF_DESTROYED)
3618 par = ncp->nc_parent;
3621 while ((par_tmp = par->nc_parent) != NULL &&
3622 par_tmp->nc_vp == NULL) {
3623 _cache_hold(par_tmp);
3624 _cache_lock(par_tmp);
3628 if (par->nc_parent == NULL) {
3629 kprintf("EXDEV case 2 %*.*s\n",
3630 par->nc_nlen, par->nc_nlen, par->nc_name);
3635 * The parent is not set in stone, ref and lock it to prevent
3636 * it from disappearing. Also note that due to renames it
3637 * is possible for our ncp to move and for par to no longer
3638 * be one of its parents. We resolve it anyway, the loop
3639 * will handle any moves.
3641 _cache_get(par); /* additional hold/lock */
3642 _cache_put(par); /* from earlier hold/lock */
3643 if (par == nch->mount->mnt_ncmountpt.ncp) {
3644 cache_resolve_mp(nch->mount);
3645 } else if ((dvp = cache_dvpref(par)) == NULL) {
3646 kprintf("[diagnostic] cache_resolve: raced on %*.*s\n", par->nc_nlen, par->nc_nlen, par->nc_name);
3650 if (par->nc_flag & NCF_UNRESOLVED) {
3653 par->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred);
3657 if ((error = par->nc_error) != 0) {
3658 if (par->nc_error != EAGAIN) {
3659 kprintf("EXDEV case 3 %*.*s error %d\n",
3660 par->nc_nlen, par->nc_nlen, par->nc_name,
3665 kprintf("[diagnostic] cache_resolve: EAGAIN par %p %*.*s\n",
3666 par, par->nc_nlen, par->nc_nlen, par->nc_name);
3673 * Call VOP_NRESOLVE() to get the vp, then scan for any disconnected
3674 * ncp's and reattach them. If this occurs the original ncp is marked
3675 * EAGAIN to force a relookup.
3677 * NOTE: in order to call VOP_NRESOLVE(), the parent of the passed
3678 * ncp must already be resolved.
3683 ncp->nc_error = VOP_NRESOLVE(&nctmp, dvp, cred);
3686 ncp->nc_error = EPERM;
3688 if (ncp->nc_error == EAGAIN) {
3689 kprintf("[diagnostic] cache_resolve: EAGAIN ncp %p %*.*s\n",
3690 ncp, ncp->nc_nlen, ncp->nc_nlen, ncp->nc_name);
3693 return(ncp->nc_error);
3697 * Resolve the ncp associated with a mount point. Such ncp's almost always
3698 * remain resolved and this routine is rarely called. NFS MPs tends to force
3699 * re-resolution more often due to its mac-truck-smash-the-namecache
3700 * method of tracking namespace changes.
3702 * The semantics for this call is that the passed ncp must be locked on
3703 * entry and will be locked on return. However, if we actually have to
3704 * resolve the mount point we temporarily unlock the entry in order to
3705 * avoid race-to-root deadlocks due to e.g. dead NFS mounts. Because of
3706 * the unlock we have to recheck the flags after we relock.
3709 cache_resolve_mp(struct mount *mp)
3711 struct namecache *ncp = mp->mnt_ncmountpt.ncp;
3715 KKASSERT(mp != NULL);
3718 * If the ncp is already resolved we have nothing to do. However,
3719 * we do want to guarentee that a usable vnode is returned when
3720 * a vnode is present, so make sure it hasn't been reclaimed.
3722 if ((ncp->nc_flag & NCF_UNRESOLVED) == 0) {
3723 if (ncp->nc_vp && (ncp->nc_vp->v_flag & VRECLAIMED))
3724 _cache_setunresolved(ncp);
3727 if (ncp->nc_flag & NCF_UNRESOLVED) {
3729 while (vfs_busy(mp, 0))
3731 error = VFS_ROOT(mp, &vp);
3735 * recheck the ncp state after relocking.
3737 if (ncp->nc_flag & NCF_UNRESOLVED) {
3738 ncp->nc_error = error;
3740 _cache_setvp(mp, ncp, vp);
3743 kprintf("[diagnostic] cache_resolve_mp: failed"
3744 " to resolve mount %p err=%d ncp=%p\n",
3746 _cache_setvp(mp, ncp, NULL);
3748 } else if (error == 0) {
3753 return(ncp->nc_error);
3757 * Clean out negative cache entries when too many have accumulated.
3760 _cache_cleanneg(int count)
3762 struct namecache *ncp;
3765 * Attempt to clean out the specified number of negative cache
3769 spin_lock(&ncneg.spin);
3770 ncp = TAILQ_FIRST(&ncneg.list);
3772 spin_unlock(&ncneg.spin);
3775 TAILQ_REMOVE(&ncneg.list, ncp, nc_vnode);
3776 TAILQ_INSERT_TAIL(&ncneg.list, ncp, nc_vnode);
3778 spin_unlock(&ncneg.spin);
3781 * This can race, so we must re-check that the ncp
3782 * is on the ncneg.list after successfully locking it.
3784 if (_cache_lock_special(ncp) == 0) {
3785 if (ncp->nc_vp == NULL &&
3786 (ncp->nc_flag & NCF_UNRESOLVED) == 0) {
3787 ncp = cache_zap(ncp, 1);
3791 kprintf("cache_cleanneg: race avoided\n");
3802 * Clean out positive cache entries when too many have accumulated.
3805 _cache_cleanpos(int count)
3807 static volatile int rover;
3808 struct nchash_head *nchpp;
3809 struct namecache *ncp;
3813 * Attempt to clean out the specified number of negative cache
3817 rover_copy = ++rover; /* MPSAFEENOUGH */
3819 nchpp = NCHHASH(rover_copy);
3821 spin_lock_shared(&nchpp->spin);
3822 ncp = LIST_FIRST(&nchpp->list);
3823 while (ncp && (ncp->nc_flag & NCF_DESTROYED))
3824 ncp = LIST_NEXT(ncp, nc_hash);
3827 spin_unlock_shared(&nchpp->spin);
3830 if (_cache_lock_special(ncp) == 0) {
3831 ncp = cache_zap(ncp, 1);
3843 * This is a kitchen sink function to clean out ncps which we
3844 * tried to zap from cache_drop() but failed because we were
3845 * unable to acquire the parent lock.
3847 * Such entries can also be removed via cache_inval_vp(), such
3848 * as when unmounting.
3851 _cache_cleandefered(void)
3853 struct nchash_head *nchpp;
3854 struct namecache *ncp;
3855 struct namecache dummy;
3859 bzero(&dummy, sizeof(dummy));
3860 dummy.nc_flag = NCF_DESTROYED;
3863 for (i = 0; i <= nchash; ++i) {
3864 nchpp = &nchashtbl[i];
3866 spin_lock(&nchpp->spin);
3867 LIST_INSERT_HEAD(&nchpp->list, &dummy, nc_hash);
3869 while ((ncp = LIST_NEXT(ncp, nc_hash)) != NULL) {
3870 if ((ncp->nc_flag & NCF_DEFEREDZAP) == 0)
3872 LIST_REMOVE(&dummy, nc_hash);
3873 LIST_INSERT_AFTER(ncp, &dummy, nc_hash);
3875 spin_unlock(&nchpp->spin);
3876 if (_cache_lock_nonblock(ncp) == 0) {
3877 ncp->nc_flag &= ~NCF_DEFEREDZAP;
3881 spin_lock(&nchpp->spin);
3884 LIST_REMOVE(&dummy, nc_hash);
3885 spin_unlock(&nchpp->spin);
3890 * Name cache initialization, from vfsinit() when we are booting
3899 * Initialise per-cpu namecache effectiveness statistics.
3901 for (i = 0; i < ncpus; ++i) {
3902 gd = globaldata_find(i);
3903 gd->gd_nchstats = &nchstats[i];
3907 * Create a generous namecache hash table
3909 TAILQ_INIT(&ncneg.list);
3910 spin_init(&ncneg.spin, "nchinit");
3911 nchashtbl = hashinit_ext(vfs_inodehashsize(),
3912 sizeof(struct nchash_head),
3913 M_VFSCACHE, &nchash);
3914 for (i = 0; i <= (int)nchash; ++i) {
3915 LIST_INIT(&nchashtbl[i].list);
3916 spin_init(&nchashtbl[i].spin, "nchinit_hash");
3918 for (i = 0; i < NCMOUNT_NUMCACHE; ++i)
3919 spin_init(&ncmount_cache[i].spin, "nchinit_cache");
3920 nclockwarn = 5 * hz;
3924 * Called from start_init() to bootstrap the root filesystem. Returns
3925 * a referenced, unlocked namecache record.
3928 cache_allocroot(struct nchandle *nch, struct mount *mp, struct vnode *vp)
3930 nch->ncp = cache_alloc(0);
3934 _cache_setvp(nch->mount, nch->ncp, vp);
3938 * vfs_cache_setroot()
3940 * Create an association between the root of our namecache and
3941 * the root vnode. This routine may be called several times during
3944 * If the caller intends to save the returned namecache pointer somewhere
3945 * it must cache_hold() it.
3948 vfs_cache_setroot(struct vnode *nvp, struct nchandle *nch)
3951 struct nchandle onch;
3959 cache_zero(&rootnch);
3967 * XXX OLD API COMPAT FUNCTION. This really messes up the new namecache
3968 * topology and is being removed as quickly as possible. The new VOP_N*()
3969 * API calls are required to make specific adjustments using the supplied
3970 * ncp pointers rather then just bogusly purging random vnodes.
3972 * Invalidate all namecache entries to a particular vnode as well as
3973 * any direct children of that vnode in the namecache. This is a
3974 * 'catch all' purge used by filesystems that do not know any better.
3976 * Note that the linkage between the vnode and its namecache entries will
3977 * be removed, but the namecache entries themselves might stay put due to
3978 * active references from elsewhere in the system or due to the existance of
3979 * the children. The namecache topology is left intact even if we do not
3980 * know what the vnode association is. Such entries will be marked
3984 cache_purge(struct vnode *vp)
3986 cache_inval_vp(vp, CINV_DESTROY | CINV_CHILDREN);
3989 static int disablecwd;
3990 SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0,
3993 static u_long numcwdcalls;
3994 SYSCTL_ULONG(_vfs_cache, OID_AUTO, numcwdcalls, CTLFLAG_RD, &numcwdcalls, 0,
3995 "Number of current directory resolution calls");
3996 static u_long numcwdfailnf;
3997 SYSCTL_ULONG(_vfs_cache, OID_AUTO, numcwdfailnf, CTLFLAG_RD, &numcwdfailnf, 0,
3998 "Number of current directory failures due to lack of file");
3999 static u_long numcwdfailsz;
4000 SYSCTL_ULONG(_vfs_cache, OID_AUTO, numcwdfailsz, CTLFLAG_RD, &numcwdfailsz, 0,
4001 "Number of current directory failures due to large result");
4002 static u_long numcwdfound;
4003 SYSCTL_ULONG(_vfs_cache, OID_AUTO, numcwdfound, CTLFLAG_RD, &numcwdfound, 0,
4004 "Number of current directory resolution successes");
4010 sys___getcwd(struct __getcwd_args *uap)
4020 buflen = uap->buflen;
4023 if (buflen > MAXPATHLEN)
4024 buflen = MAXPATHLEN;
4026 buf = kmalloc(buflen, M_TEMP, M_WAITOK);
4027 bp = kern_getcwd(buf, buflen, &error);
4029 error = copyout(bp, uap->buf, strlen(bp) + 1);
4035 kern_getcwd(char *buf, size_t buflen, int *error)
4037 struct proc *p = curproc;
4039 int i, slash_prefixed;
4040 struct filedesc *fdp;
4041 struct nchandle nch;
4042 struct namecache *ncp;
4051 nch = fdp->fd_ncdir;
4056 while (ncp && (ncp != fdp->fd_nrdir.ncp ||
4057 nch.mount != fdp->fd_nrdir.mount)
4060 * While traversing upwards if we encounter the root
4061 * of the current mount we have to skip to the mount point
4062 * in the underlying filesystem.
4064 if (ncp == nch.mount->mnt_ncmountpt.ncp) {
4065 nch = nch.mount->mnt_ncmounton;
4074 * Prepend the path segment
4076 for (i = ncp->nc_nlen - 1; i >= 0; i--) {
4083 *--bp = ncp->nc_name[i];
4095 * Go up a directory. This isn't a mount point so we don't
4096 * have to check again.
4098 while ((nch.ncp = ncp->nc_parent) != NULL) {
4099 if (ncp_shared_lock_disable)
4102 _cache_lock_shared(ncp);
4103 if (nch.ncp != ncp->nc_parent) {
4107 _cache_hold(nch.ncp);
4120 if (!slash_prefixed) {
4138 * Thus begins the fullpath magic.
4140 * The passed nchp is referenced but not locked.
4142 static int disablefullpath;
4143 SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW,
4144 &disablefullpath, 0,
4145 "Disable fullpath lookups");
4147 static u_int numfullpathcalls;
4148 SYSCTL_UINT(_vfs_cache, OID_AUTO, numfullpathcalls, CTLFLAG_RD,
4149 &numfullpathcalls, 0,
4150 "Number of full path resolutions in progress");
4151 static u_int numfullpathfailnf;
4152 SYSCTL_UINT(_vfs_cache, OID_AUTO, numfullpathfailnf, CTLFLAG_RD,
4153 &numfullpathfailnf, 0,
4154 "Number of full path resolution failures due to lack of file");
4155 static u_int numfullpathfailsz;
4156 SYSCTL_UINT(_vfs_cache, OID_AUTO, numfullpathfailsz, CTLFLAG_RD,
4157 &numfullpathfailsz, 0,
4158 "Number of full path resolution failures due to insufficient memory");
4159 static u_int numfullpathfound;
4160 SYSCTL_UINT(_vfs_cache, OID_AUTO, numfullpathfound, CTLFLAG_RD,
4161 &numfullpathfound, 0,
4162 "Number of full path resolution successes");
4165 cache_fullpath(struct proc *p, struct nchandle *nchp, struct nchandle *nchbase,
4166 char **retbuf, char **freebuf, int guess)
4168 struct nchandle fd_nrdir;
4169 struct nchandle nch;
4170 struct namecache *ncp;
4171 struct mount *mp, *new_mp;
4177 atomic_add_int(&numfullpathcalls, -1);
4182 buf = kmalloc(MAXPATHLEN, M_TEMP, M_WAITOK);
4183 bp = buf + MAXPATHLEN - 1;
4186 fd_nrdir = *nchbase;
4188 fd_nrdir = p->p_fd->fd_nrdir;
4198 while (ncp && (ncp != fd_nrdir.ncp || mp != fd_nrdir.mount)) {
4202 * If we are asked to guess the upwards path, we do so whenever
4203 * we encounter an ncp marked as a mountpoint. We try to find
4204 * the actual mountpoint by finding the mountpoint with this
4207 if (guess && (ncp->nc_flag & NCF_ISMOUNTPT)) {
4208 new_mp = mount_get_by_nc(ncp);
4211 * While traversing upwards if we encounter the root
4212 * of the current mount we have to skip to the mount point.
4214 if (ncp == mp->mnt_ncmountpt.ncp) {
4218 nch = new_mp->mnt_ncmounton;
4228 * Prepend the path segment
4230 for (i = ncp->nc_nlen - 1; i >= 0; i--) {
4232 numfullpathfailsz++;
4237 *--bp = ncp->nc_name[i];
4240 numfullpathfailsz++;
4249 * Go up a directory. This isn't a mount point so we don't
4250 * have to check again.
4252 * We can only safely access nc_parent with ncp held locked.
4254 while ((nch.ncp = ncp->nc_parent) != NULL) {
4256 if (nch.ncp != ncp->nc_parent) {
4260 _cache_hold(nch.ncp);
4268 numfullpathfailnf++;
4274 if (!slash_prefixed) {
4276 numfullpathfailsz++;
4294 vn_fullpath(struct proc *p, struct vnode *vn, char **retbuf,
4295 char **freebuf, int guess)
4297 struct namecache *ncp;
4298 struct nchandle nch;
4302 atomic_add_int(&numfullpathcalls, 1);
4303 if (disablefullpath)
4309 /* vn is NULL, client wants us to use p->p_textvp */
4311 if ((vn = p->p_textvp) == NULL)
4314 spin_lock_shared(&vn->v_spin);
4315 TAILQ_FOREACH(ncp, &vn->v_namecache, nc_vnode) {
4320 spin_unlock_shared(&vn->v_spin);
4324 spin_unlock_shared(&vn->v_spin);
4326 atomic_add_int(&numfullpathcalls, -1);
4328 nch.mount = vn->v_mount;
4329 error = cache_fullpath(p, &nch, NULL, retbuf, freebuf, guess);