/*- * Copyright (c) 1989, 1993, 1995 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Poul-Henning Kamp of the FreeBSD Project. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)vfs_cache.c 8.5 (Berkeley) 3/22/95 */ #include __FBSDID("$FreeBSD$"); #include "opt_kdtrace.h" #include "opt_ktrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef KTRACE #include #endif #include SDT_PROVIDER_DECLARE(vfs); SDT_PROBE_DEFINE3(vfs, namecache, enter, done, "struct vnode *", "char *", "struct vnode *"); SDT_PROBE_DEFINE2(vfs, namecache, enter_negative, done, "struct vnode *", "char *"); SDT_PROBE_DEFINE1(vfs, namecache, fullpath, entry, "struct vnode *"); SDT_PROBE_DEFINE3(vfs, namecache, fullpath, hit, "struct vnode *", "char *", "struct vnode *"); SDT_PROBE_DEFINE1(vfs, namecache, fullpath, miss, "struct vnode *"); SDT_PROBE_DEFINE3(vfs, namecache, fullpath, return, "int", "struct vnode *", "char *"); SDT_PROBE_DEFINE3(vfs, namecache, lookup, hit, "struct vnode *", "char *", "struct vnode *"); SDT_PROBE_DEFINE2(vfs, namecache, lookup, hit__negative, "struct vnode *", "char *"); SDT_PROBE_DEFINE2(vfs, namecache, lookup, miss, "struct vnode *", "char *"); SDT_PROBE_DEFINE1(vfs, namecache, purge, done, "struct vnode *"); SDT_PROBE_DEFINE1(vfs, namecache, purge_negative, done, "struct vnode *"); SDT_PROBE_DEFINE1(vfs, namecache, purgevfs, done, "struct mount *"); SDT_PROBE_DEFINE3(vfs, namecache, zap, done, "struct vnode *", "char *", "struct vnode *"); SDT_PROBE_DEFINE2(vfs, namecache, zap_negative, done, "struct vnode *", "char *"); /* * This structure describes the elements in the cache of recent * names looked up by namei. */ struct namecache { LIST_ENTRY(namecache) nc_hash; /* hash chain */ LIST_ENTRY(namecache) nc_src; /* source vnode list */ TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ struct vnode *nc_dvp; /* vnode of parent of name */ struct vnode *nc_vp; /* vnode the name refers to */ u_char nc_flag; /* flag bits */ u_char nc_nlen; /* length of name */ char nc_name[0]; /* segment name + nul */ }; /* * struct namecache_ts repeats struct namecache layout up to the * nc_nlen member. * struct namecache_ts is used in place of struct namecache when time(s) need * to be stored. The nc_dotdottime field is used when a cache entry is mapping * both a non-dotdot directory name plus dotdot for the directory's * parent. */ struct namecache_ts { LIST_ENTRY(namecache) nc_hash; /* hash chain */ LIST_ENTRY(namecache) nc_src; /* source vnode list */ TAILQ_ENTRY(namecache) nc_dst; /* destination vnode list */ struct vnode *nc_dvp; /* vnode of parent of name */ struct vnode *nc_vp; /* vnode the name refers to */ u_char nc_flag; /* flag bits */ u_char nc_nlen; /* length of name */ struct timespec nc_time; /* timespec provided by fs */ struct timespec nc_dotdottime; /* dotdot timespec provided by fs */ int nc_ticks; /* ticks value when entry was added */ char nc_name[0]; /* segment name + nul */ }; /* * Flags in namecache.nc_flag */ #define NCF_WHITE 0x01 #define NCF_ISDOTDOT 0x02 #define NCF_TS 0x04 #define NCF_DTS 0x08 /* * Name caching works as follows: * * Names found by directory scans are retained in a cache * for future reference. It is managed LRU, so frequently * used names will hang around. Cache is indexed by hash value * obtained from (vp, name) where vp refers to the directory * containing name. * * If it is a "negative" entry, (i.e. for a name that is known NOT to * exist) the vnode pointer will be NULL. * * Upon reaching the last segment of a path, if the reference * is for DELETE, or NOCACHE is set (rewrite), and the * name is located in the cache, it will be dropped. */ /* * Structures associated with name cacheing. */ #define NCHHASH(hash) \ (&nchashtbl[(hash) & nchash]) static LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ static TAILQ_HEAD(, namecache) ncneg; /* Hash Table */ static u_long nchash; /* size of hash table */ SYSCTL_ULONG(_debug, OID_AUTO, nchash, CTLFLAG_RD, &nchash, 0, "Size of namecache hash table"); static u_long ncnegfactor = 16; /* ratio of negative entries */ SYSCTL_ULONG(_vfs, OID_AUTO, ncnegfactor, CTLFLAG_RW, &ncnegfactor, 0, "Ratio of negative namecache entries"); static u_long numneg; /* number of negative entries allocated */ SYSCTL_ULONG(_debug, OID_AUTO, numneg, CTLFLAG_RD, &numneg, 0, "Number of negative entries in namecache"); static u_long numcache; /* number of cache entries allocated */ SYSCTL_ULONG(_debug, OID_AUTO, numcache, CTLFLAG_RD, &numcache, 0, "Number of namecache entries"); static u_long numcachehv; /* number of cache entries with vnodes held */ SYSCTL_ULONG(_debug, OID_AUTO, numcachehv, CTLFLAG_RD, &numcachehv, 0, "Number of namecache entries with vnodes held"); static u_int ncsizefactor = 2; SYSCTL_UINT(_vfs, OID_AUTO, ncsizefactor, CTLFLAG_RW, &ncsizefactor, 0, "Size factor for namecache"); struct nchstats nchstats; /* cache effectiveness statistics */ static struct rwlock cache_lock; RW_SYSINIT(vfscache, &cache_lock, "Name Cache"); #define CACHE_UPGRADE_LOCK() rw_try_upgrade(&cache_lock) #define CACHE_RLOCK() rw_rlock(&cache_lock) #define CACHE_RUNLOCK() rw_runlock(&cache_lock) #define CACHE_WLOCK() rw_wlock(&cache_lock) #define CACHE_WUNLOCK() rw_wunlock(&cache_lock) /* * UMA zones for the VFS cache. * * The small cache is used for entries with short names, which are the * most common. The large cache is used for entries which are too big to * fit in the small cache. */ static uma_zone_t cache_zone_small; static uma_zone_t cache_zone_small_ts; static uma_zone_t cache_zone_large; static uma_zone_t cache_zone_large_ts; #define CACHE_PATH_CUTOFF 35 static struct namecache * cache_alloc(int len, int ts) { if (len > CACHE_PATH_CUTOFF) { if (ts) return (uma_zalloc(cache_zone_large_ts, M_WAITOK)); else return (uma_zalloc(cache_zone_large, M_WAITOK)); } if (ts) return (uma_zalloc(cache_zone_small_ts, M_WAITOK)); else return (uma_zalloc(cache_zone_small, M_WAITOK)); } static void cache_free(struct namecache *ncp) { int ts; if (ncp == NULL) return; ts = ncp->nc_flag & NCF_TS; if (ncp->nc_nlen <= CACHE_PATH_CUTOFF) { if (ts) uma_zfree(cache_zone_small_ts, ncp); else uma_zfree(cache_zone_small, ncp); } else if (ts) uma_zfree(cache_zone_large_ts, ncp); else uma_zfree(cache_zone_large, ncp); } static char * nc_get_name(struct namecache *ncp) { struct namecache_ts *ncp_ts; if ((ncp->nc_flag & NCF_TS) == 0) return (ncp->nc_name); ncp_ts = (struct namecache_ts *)ncp; return (ncp_ts->nc_name); } static void cache_out_ts(struct namecache *ncp, struct timespec *tsp, int *ticksp) { KASSERT((ncp->nc_flag & NCF_TS) != 0 || (tsp == NULL && ticksp == NULL), ("No NCF_TS")); if (tsp != NULL) *tsp = ((struct namecache_ts *)ncp)->nc_time; if (ticksp != NULL) *ticksp = ((struct namecache_ts *)ncp)->nc_ticks; } static int doingcache = 1; /* 1 => enable the cache */ SYSCTL_INT(_debug, OID_AUTO, vfscache, CTLFLAG_RW, &doingcache, 0, "VFS namecache enabled"); /* Export size information to userland */ SYSCTL_INT(_debug_sizeof, OID_AUTO, namecache, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, sizeof(struct namecache), "sizeof(struct namecache)"); /* * The new name cache statistics */ static SYSCTL_NODE(_vfs, OID_AUTO, cache, CTLFLAG_RW, 0, "Name cache statistics"); #define STATNODE(mode, name, var, descr) \ SYSCTL_ULONG(_vfs_cache, OID_AUTO, name, mode, var, 0, descr); STATNODE(CTLFLAG_RD, numneg, &numneg, "Number of negative cache entries"); STATNODE(CTLFLAG_RD, numcache, &numcache, "Number of cache entries"); static u_long numcalls; STATNODE(CTLFLAG_RD, numcalls, &numcalls, "Number of cache lookups"); static u_long dothits; STATNODE(CTLFLAG_RD, dothits, &dothits, "Number of '.' hits"); static u_long dotdothits; STATNODE(CTLFLAG_RD, dotdothits, &dotdothits, "Number of '..' hits"); static u_long numchecks; STATNODE(CTLFLAG_RD, numchecks, &numchecks, "Number of checks in lookup"); static u_long nummiss; STATNODE(CTLFLAG_RD, nummiss, &nummiss, "Number of cache misses"); static u_long nummisszap; STATNODE(CTLFLAG_RD, nummisszap, &nummisszap, "Number of cache misses we do not want to cache"); static u_long numposzaps; STATNODE(CTLFLAG_RD, numposzaps, &numposzaps, "Number of cache hits (positive) we do not want to cache"); static u_long numposhits; STATNODE(CTLFLAG_RD, numposhits, &numposhits, "Number of cache hits (positive)"); static u_long numnegzaps; STATNODE(CTLFLAG_RD, numnegzaps, &numnegzaps, "Number of cache hits (negative) we do not want to cache"); static u_long numneghits; STATNODE(CTLFLAG_RD, numneghits, &numneghits, "Number of cache hits (negative)"); static u_long numupgrades; STATNODE(CTLFLAG_RD, numupgrades, &numupgrades, "Number of updates of the cache after lookup (write lock + retry)"); SYSCTL_OPAQUE(_vfs_cache, OID_AUTO, nchstats, CTLFLAG_RD | CTLFLAG_MPSAFE, &nchstats, sizeof(nchstats), "LU", "VFS cache effectiveness statistics"); static void cache_zap(struct namecache *ncp); static int vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen); static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf, u_int buflen); static MALLOC_DEFINE(M_VFSCACHE, "vfscache", "VFS name cache entries"); #ifdef DIAGNOSTIC /* * Grab an atomic snapshot of the name cache hash chain lengths */ static SYSCTL_NODE(_debug, OID_AUTO, hashstat, CTLFLAG_RW, NULL, "hash table stats"); static int sysctl_debug_hashstat_rawnchash(SYSCTL_HANDLER_ARGS) { int error; struct nchashhead *ncpp; struct namecache *ncp; int n_nchash; int count; n_nchash = nchash + 1; /* nchash is max index, not count */ if (!req->oldptr) return SYSCTL_OUT(req, 0, n_nchash * sizeof(int)); /* Scan hash tables for applicable entries */ for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { CACHE_RLOCK(); count = 0; LIST_FOREACH(ncp, ncpp, nc_hash) { count++; } CACHE_RUNLOCK(); error = SYSCTL_OUT(req, &count, sizeof(count)); if (error) return (error); } return (0); } SYSCTL_PROC(_debug_hashstat, OID_AUTO, rawnchash, CTLTYPE_INT|CTLFLAG_RD| CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_rawnchash, "S,int", "nchash chain lengths"); static int sysctl_debug_hashstat_nchash(SYSCTL_HANDLER_ARGS) { int error; struct nchashhead *ncpp; struct namecache *ncp; int n_nchash; int count, maxlength, used, pct; if (!req->oldptr) return SYSCTL_OUT(req, 0, 4 * sizeof(int)); n_nchash = nchash + 1; /* nchash is max index, not count */ used = 0; maxlength = 0; /* Scan hash tables for applicable entries */ for (ncpp = nchashtbl; n_nchash > 0; n_nchash--, ncpp++) { count = 0; CACHE_RLOCK(); LIST_FOREACH(ncp, ncpp, nc_hash) { count++; } CACHE_RUNLOCK(); if (count) used++; if (maxlength < count) maxlength = count; } n_nchash = nchash + 1; pct = (used * 100) / (n_nchash / 100); error = SYSCTL_OUT(req, &n_nchash, sizeof(n_nchash)); if (error) return (error); error = SYSCTL_OUT(req, &used, sizeof(used)); if (error) return (error); error = SYSCTL_OUT(req, &maxlength, sizeof(maxlength)); if (error) return (error); error = SYSCTL_OUT(req, &pct, sizeof(pct)); if (error) return (error); return (0); } SYSCTL_PROC(_debug_hashstat, OID_AUTO, nchash, CTLTYPE_INT|CTLFLAG_RD| CTLFLAG_MPSAFE, 0, 0, sysctl_debug_hashstat_nchash, "I", "nchash statistics (number of total/used buckets, maximum chain length, usage percentage)"); #endif /* * cache_zap(): * * Removes a namecache entry from cache, whether it contains an actual * pointer to a vnode or if it is just a negative cache entry. */ static void cache_zap(ncp) struct namecache *ncp; { struct vnode *vp; rw_assert(&cache_lock, RA_WLOCKED); CTR2(KTR_VFS, "cache_zap(%p) vp %p", ncp, ncp->nc_vp); #ifdef KDTRACE_HOOKS if (ncp->nc_vp != NULL) { SDT_PROBE(vfs, namecache, zap, done, ncp->nc_dvp, nc_get_name(ncp), ncp->nc_vp, 0, 0); } else { SDT_PROBE(vfs, namecache, zap_negative, done, ncp->nc_dvp, nc_get_name(ncp), 0, 0, 0); } #endif vp = NULL; LIST_REMOVE(ncp, nc_hash); if (ncp->nc_flag & NCF_ISDOTDOT) { if (ncp == ncp->nc_dvp->v_cache_dd) ncp->nc_dvp->v_cache_dd = NULL; } else { LIST_REMOVE(ncp, nc_src); if (LIST_EMPTY(&ncp->nc_dvp->v_cache_src)) { vp = ncp->nc_dvp; numcachehv--; } } if (ncp->nc_vp) { TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); if (ncp == ncp->nc_vp->v_cache_dd) ncp->nc_vp->v_cache_dd = NULL; } else { TAILQ_REMOVE(&ncneg, ncp, nc_dst); numneg--; } numcache--; cache_free(ncp); if (vp) vdrop(vp); } /* * Lookup an entry in the cache * * Lookup is called with dvp pointing to the directory to search, * cnp pointing to the name of the entry being sought. If the lookup * succeeds, the vnode is returned in *vpp, and a status of -1 is * returned. If the lookup determines that the name does not exist * (negative cacheing), a status of ENOENT is returned. If the lookup * fails, a status of zero is returned. If the directory vnode is * recycled out from under us due to a forced unmount, a status of * ENOENT is returned. * * vpp is locked and ref'd on return. If we're looking up DOTDOT, dvp is * unlocked. If we're looking up . an extra ref is taken, but the lock is * not recursively acquired. */ int cache_lookup(dvp, vpp, cnp, tsp, ticksp) struct vnode *dvp; struct vnode **vpp; struct componentname *cnp; struct timespec *tsp; int *ticksp; { struct namecache *ncp; uint32_t hash; int error, ltype, wlocked; if (!doingcache) { cnp->cn_flags &= ~MAKEENTRY; return (0); } retry: CACHE_RLOCK(); wlocked = 0; numcalls++; error = 0; retry_wlocked: if (cnp->cn_nameptr[0] == '.') { if (cnp->cn_namelen == 1) { *vpp = dvp; CTR2(KTR_VFS, "cache_lookup(%p, %s) found via .", dvp, cnp->cn_nameptr); dothits++; SDT_PROBE(vfs, namecache, lookup, hit, dvp, ".", *vpp, 0, 0); if (tsp != NULL) timespecclear(tsp); if (ticksp != NULL) *ticksp = ticks; goto success; } if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { dotdothits++; if (dvp->v_cache_dd == NULL) { SDT_PROBE(vfs, namecache, lookup, miss, dvp, "..", NULL, 0, 0); goto unlock; } if ((cnp->cn_flags & MAKEENTRY) == 0) { if (!wlocked && !CACHE_UPGRADE_LOCK()) goto wlock; if (dvp->v_cache_dd->nc_flag & NCF_ISDOTDOT) cache_zap(dvp->v_cache_dd); dvp->v_cache_dd = NULL; CACHE_WUNLOCK(); return (0); } ncp = dvp->v_cache_dd; if (ncp->nc_flag & NCF_ISDOTDOT) *vpp = ncp->nc_vp; else *vpp = ncp->nc_dvp; /* Return failure if negative entry was found. */ if (*vpp == NULL) goto negative_success; CTR3(KTR_VFS, "cache_lookup(%p, %s) found %p via ..", dvp, cnp->cn_nameptr, *vpp); SDT_PROBE(vfs, namecache, lookup, hit, dvp, "..", *vpp, 0, 0); cache_out_ts(ncp, tsp, ticksp); if ((ncp->nc_flag & (NCF_ISDOTDOT | NCF_DTS)) == NCF_DTS && tsp != NULL) *tsp = ((struct namecache_ts *)ncp)-> nc_dotdottime; goto success; } } hash = fnv_32_buf(cnp->cn_nameptr, cnp->cn_namelen, FNV1_32_INIT); hash = fnv_32_buf(&dvp, sizeof(dvp), hash); LIST_FOREACH(ncp, (NCHHASH(hash)), nc_hash) { numchecks++; if (ncp->nc_dvp == dvp && ncp->nc_nlen == cnp->cn_namelen && !bcmp(nc_get_name(ncp), cnp->cn_nameptr, ncp->nc_nlen)) break; } /* We failed to find an entry */ if (ncp == NULL) { SDT_PROBE(vfs, namecache, lookup, miss, dvp, cnp->cn_nameptr, NULL, 0, 0); if ((cnp->cn_flags & MAKEENTRY) == 0) { nummisszap++; } else { nummiss++; } nchstats.ncs_miss++; goto unlock; } /* We don't want to have an entry, so dump it */ if ((cnp->cn_flags & MAKEENTRY) == 0) { numposzaps++; nchstats.ncs_badhits++; if (!wlocked && !CACHE_UPGRADE_LOCK()) goto wlock; cache_zap(ncp); CACHE_WUNLOCK(); return (0); } /* We found a "positive" match, return the vnode */ if (ncp->nc_vp) { numposhits++; nchstats.ncs_goodhits++; *vpp = ncp->nc_vp; CTR4(KTR_VFS, "cache_lookup(%p, %s) found %p via ncp %p", dvp, cnp->cn_nameptr, *vpp, ncp); SDT_PROBE(vfs, namecache, lookup, hit, dvp, nc_get_name(ncp), *vpp, 0, 0); cache_out_ts(ncp, tsp, ticksp); goto success; } negative_success: /* We found a negative match, and want to create it, so purge */ if (cnp->cn_nameiop == CREATE) { numnegzaps++; nchstats.ncs_badhits++; if (!wlocked && !CACHE_UPGRADE_LOCK()) goto wlock; cache_zap(ncp); CACHE_WUNLOCK(); return (0); } if (!wlocked && !CACHE_UPGRADE_LOCK()) goto wlock; numneghits++; /* * We found a "negative" match, so we shift it to the end of * the "negative" cache entries queue to satisfy LRU. Also, * check to see if the entry is a whiteout; indicate this to * the componentname, if so. */ TAILQ_REMOVE(&ncneg, ncp, nc_dst); TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); nchstats.ncs_neghits++; if (ncp->nc_flag & NCF_WHITE) cnp->cn_flags |= ISWHITEOUT; SDT_PROBE(vfs, namecache, lookup, hit__negative, dvp, nc_get_name(ncp), 0, 0, 0); cache_out_ts(ncp, tsp, ticksp); CACHE_WUNLOCK(); return (ENOENT); wlock: /* * We need to update the cache after our lookup, so upgrade to * a write lock and retry the operation. */ CACHE_RUNLOCK(); CACHE_WLOCK(); numupgrades++; wlocked = 1; goto retry_wlocked; success: /* * On success we return a locked and ref'd vnode as per the lookup * protocol. */ if (dvp == *vpp) { /* lookup on "." */ VREF(*vpp); if (wlocked) CACHE_WUNLOCK(); else CACHE_RUNLOCK(); /* * When we lookup "." we still can be asked to lock it * differently... */ ltype = cnp->cn_lkflags & LK_TYPE_MASK; if (ltype != VOP_ISLOCKED(*vpp)) { if (ltype == LK_EXCLUSIVE) { vn_lock(*vpp, LK_UPGRADE | LK_RETRY); if ((*vpp)->v_iflag & VI_DOOMED) { /* forced unmount */ vrele(*vpp); *vpp = NULL; return (ENOENT); } } else vn_lock(*vpp, LK_DOWNGRADE | LK_RETRY); } return (-1); } ltype = 0; /* silence gcc warning */ if (cnp->cn_flags & ISDOTDOT) { ltype = VOP_ISLOCKED(dvp); VOP_UNLOCK(dvp, 0); } VI_LOCK(*vpp); if (wlocked) CACHE_WUNLOCK(); else CACHE_RUNLOCK(); error = vget(*vpp, cnp->cn_lkflags | LK_INTERLOCK, cnp->cn_thread); if (cnp->cn_flags & ISDOTDOT) { vn_lock(dvp, ltype | LK_RETRY); if (dvp->v_iflag & VI_DOOMED) { if (error == 0) vput(*vpp); *vpp = NULL; return (ENOENT); } } if (error) { *vpp = NULL; goto retry; } if ((cnp->cn_flags & ISLASTCN) && (cnp->cn_lkflags & LK_TYPE_MASK) == LK_EXCLUSIVE) { ASSERT_VOP_ELOCKED(*vpp, "cache_lookup"); } return (-1); unlock: if (wlocked) CACHE_WUNLOCK(); else CACHE_RUNLOCK(); return (0); } /* * Add an entry to the cache. */ void cache_enter_time(dvp, vp, cnp, tsp, dtsp) struct vnode *dvp; struct vnode *vp; struct componentname *cnp; struct timespec *tsp; struct timespec *dtsp; { struct namecache *ncp, *n2; struct namecache_ts *n3; struct nchashhead *ncpp; uint32_t hash; int flag; int hold; int zap; int len; CTR3(KTR_VFS, "cache_enter(%p, %p, %s)", dvp, vp, cnp->cn_nameptr); VNASSERT(vp == NULL || (vp->v_iflag & VI_DOOMED) == 0, vp, ("cache_enter: Adding a doomed vnode")); VNASSERT(dvp == NULL || (dvp->v_iflag & VI_DOOMED) == 0, dvp, ("cache_enter: Doomed vnode used as src")); if (!doingcache) return; /* * Avoid blowout in namecache entries. */ if (numcache >= desiredvnodes * ncsizefactor) return; flag = 0; if (cnp->cn_nameptr[0] == '.') { if (cnp->cn_namelen == 1) return; if (cnp->cn_namelen == 2 && cnp->cn_nameptr[1] == '.') { CACHE_WLOCK(); /* * If dotdot entry already exists, just retarget it * to new parent vnode, otherwise continue with new * namecache entry allocation. */ if ((ncp = dvp->v_cache_dd) != NULL && ncp->nc_flag & NCF_ISDOTDOT) { KASSERT(ncp->nc_dvp == dvp, ("wrong isdotdot parent")); if (ncp->nc_vp != NULL) { TAILQ_REMOVE(&ncp->nc_vp->v_cache_dst, ncp, nc_dst); } else { TAILQ_REMOVE(&ncneg, ncp, nc_dst); numneg--; } if (vp != NULL) { TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); } else { TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); numneg++; } ncp->nc_vp = vp; CACHE_WUNLOCK(); return; } dvp->v_cache_dd = NULL; SDT_PROBE(vfs, namecache, enter, done, dvp, "..", vp, 0, 0); CACHE_WUNLOCK(); flag = NCF_ISDOTDOT; } } hold = 0; zap = 0; /* * Calculate the hash key and setup as much of the new * namecache entry as possible before acquiring the lock. */ ncp = cache_alloc(cnp->cn_namelen, tsp != NULL); ncp->nc_vp = vp; ncp->nc_dvp = dvp; ncp->nc_flag = flag; if (tsp != NULL) { n3 = (struct namecache_ts *)ncp; n3->nc_time = *tsp; n3->nc_ticks = ticks; n3->nc_flag |= NCF_TS; if (dtsp != NULL) { n3->nc_dotdottime = *dtsp; n3->nc_flag |= NCF_DTS; } } len = ncp->nc_nlen = cnp->cn_namelen; hash = fnv_32_buf(cnp->cn_nameptr, len, FNV1_32_INIT); strlcpy(nc_get_name(ncp), cnp->cn_nameptr, len + 1); hash = fnv_32_buf(&dvp, sizeof(dvp), hash); CACHE_WLOCK(); /* * See if this vnode or negative entry is already in the cache * with this name. This can happen with concurrent lookups of * the same path name. */ ncpp = NCHHASH(hash); LIST_FOREACH(n2, ncpp, nc_hash) { if (n2->nc_dvp == dvp && n2->nc_nlen == cnp->cn_namelen && !bcmp(nc_get_name(n2), cnp->cn_nameptr, n2->nc_nlen)) { if (tsp != NULL) { KASSERT((n2->nc_flag & NCF_TS) != 0, ("no NCF_TS")); n3 = (struct namecache_ts *)n2; n3->nc_time = ((struct namecache_ts *)ncp)->nc_time; n3->nc_ticks = ((struct namecache_ts *)ncp)->nc_ticks; if (dtsp != NULL) { n3->nc_dotdottime = ((struct namecache_ts *)ncp)-> nc_dotdottime; n3->nc_flag |= NCF_DTS; } } CACHE_WUNLOCK(); cache_free(ncp); return; } } if (flag == NCF_ISDOTDOT) { /* * See if we are trying to add .. entry, but some other lookup * has populated v_cache_dd pointer already. */ if (dvp->v_cache_dd != NULL) { CACHE_WUNLOCK(); cache_free(ncp); return; } KASSERT(vp == NULL || vp->v_type == VDIR, ("wrong vnode type %p", vp)); dvp->v_cache_dd = ncp; } numcache++; if (!vp) { numneg++; if (cnp->cn_flags & ISWHITEOUT) ncp->nc_flag |= NCF_WHITE; } else if (vp->v_type == VDIR) { if (flag != NCF_ISDOTDOT) { /* * For this case, the cache entry maps both the * directory name in it and the name ".." for the * directory's parent. */ if ((n2 = vp->v_cache_dd) != NULL && (n2->nc_flag & NCF_ISDOTDOT) != 0) cache_zap(n2); vp->v_cache_dd = ncp; } } else { vp->v_cache_dd = NULL; } /* * Insert the new namecache entry into the appropriate chain * within the cache entries table. */ LIST_INSERT_HEAD(ncpp, ncp, nc_hash); if (flag != NCF_ISDOTDOT) { if (LIST_EMPTY(&dvp->v_cache_src)) { hold = 1; numcachehv++; } LIST_INSERT_HEAD(&dvp->v_cache_src, ncp, nc_src); } /* * If the entry is "negative", we place it into the * "negative" cache queue, otherwise, we place it into the * destination vnode's cache entries queue. */ if (vp) { TAILQ_INSERT_HEAD(&vp->v_cache_dst, ncp, nc_dst); SDT_PROBE(vfs, namecache, enter, done, dvp, nc_get_name(ncp), vp, 0, 0); } else { TAILQ_INSERT_TAIL(&ncneg, ncp, nc_dst); SDT_PROBE(vfs, namecache, enter_negative, done, dvp, nc_get_name(ncp), 0, 0, 0); } if (numneg * ncnegfactor > numcache) { ncp = TAILQ_FIRST(&ncneg); KASSERT(ncp->nc_vp == NULL, ("ncp %p vp %p on ncneg", ncp, ncp->nc_vp)); zap = 1; } if (hold) vhold(dvp); if (zap) cache_zap(ncp); CACHE_WUNLOCK(); } /* * Name cache initialization, from vfs_init() when we are booting */ static void nchinit(void *dummy __unused) { TAILQ_INIT(&ncneg); cache_zone_small = uma_zcreate("S VFS Cache", sizeof(struct namecache) + CACHE_PATH_CUTOFF + 1, NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); cache_zone_small_ts = uma_zcreate("STS VFS Cache", sizeof(struct namecache_ts) + CACHE_PATH_CUTOFF + 1, NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); cache_zone_large = uma_zcreate("L VFS Cache", sizeof(struct namecache) + NAME_MAX + 1, NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); cache_zone_large_ts = uma_zcreate("LTS VFS Cache", sizeof(struct namecache_ts) + NAME_MAX + 1, NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_ZINIT); nchashtbl = hashinit(desiredvnodes * 2, M_VFSCACHE, &nchash); } SYSINIT(vfs, SI_SUB_VFS, SI_ORDER_SECOND, nchinit, NULL); /* * Invalidate all entries to a particular vnode. */ void cache_purge(vp) struct vnode *vp; { CTR1(KTR_VFS, "cache_purge(%p)", vp); SDT_PROBE(vfs, namecache, purge, done, vp, 0, 0, 0, 0); CACHE_WLOCK(); while (!LIST_EMPTY(&vp->v_cache_src)) cache_zap(LIST_FIRST(&vp->v_cache_src)); while (!TAILQ_EMPTY(&vp->v_cache_dst)) cache_zap(TAILQ_FIRST(&vp->v_cache_dst)); if (vp->v_cache_dd != NULL) { KASSERT(vp->v_cache_dd->nc_flag & NCF_ISDOTDOT, ("lost dotdot link")); cache_zap(vp->v_cache_dd); } KASSERT(vp->v_cache_dd == NULL, ("incomplete purge")); CACHE_WUNLOCK(); } /* * Invalidate all negative entries for a particular directory vnode. */ void cache_purge_negative(vp) struct vnode *vp; { struct namecache *cp, *ncp; CTR1(KTR_VFS, "cache_purge_negative(%p)", vp); SDT_PROBE(vfs, namecache, purge_negative, done, vp, 0, 0, 0, 0); CACHE_WLOCK(); LIST_FOREACH_SAFE(cp, &vp->v_cache_src, nc_src, ncp) { if (cp->nc_vp == NULL) cache_zap(cp); } CACHE_WUNLOCK(); } /* * Flush all entries referencing a particular filesystem. */ void cache_purgevfs(mp) struct mount *mp; { struct nchashhead *ncpp; struct namecache *ncp, *nnp; /* Scan hash tables for applicable entries */ SDT_PROBE(vfs, namecache, purgevfs, done, mp, 0, 0, 0, 0); CACHE_WLOCK(); for (ncpp = &nchashtbl[nchash]; ncpp >= nchashtbl; ncpp--) { LIST_FOREACH_SAFE(ncp, ncpp, nc_hash, nnp) { if (ncp->nc_dvp->v_mount == mp) cache_zap(ncp); } } CACHE_WUNLOCK(); } /* * Perform canonical checks and cache lookup and pass on to filesystem * through the vop_cachedlookup only if needed. */ int vfs_cache_lookup(ap) struct vop_lookup_args /* { struct vnode *a_dvp; struct vnode **a_vpp; struct componentname *a_cnp; } */ *ap; { struct vnode *dvp; int error; struct vnode **vpp = ap->a_vpp; struct componentname *cnp = ap->a_cnp; struct ucred *cred = cnp->cn_cred; int flags = cnp->cn_flags; struct thread *td = cnp->cn_thread; *vpp = NULL; dvp = ap->a_dvp; if (dvp->v_type != VDIR) return (ENOTDIR); if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) && (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) return (EROFS); error = VOP_ACCESS(dvp, VEXEC, cred, td); if (error) return (error); error = cache_lookup(dvp, vpp, cnp, NULL, NULL); if (error == 0) return (VOP_CACHEDLOOKUP(dvp, vpp, cnp)); if (error == -1) return (0); return (error); } /* * XXX All of these sysctls would probably be more productive dead. */ static int disablecwd; SYSCTL_INT(_debug, OID_AUTO, disablecwd, CTLFLAG_RW, &disablecwd, 0, "Disable the getcwd syscall"); /* Implementation of the getcwd syscall. */ int sys___getcwd(td, uap) struct thread *td; struct __getcwd_args *uap; { return (kern___getcwd(td, uap->buf, UIO_USERSPACE, uap->buflen)); } int kern___getcwd(struct thread *td, char *buf, enum uio_seg bufseg, u_int buflen) { char *bp, *tmpbuf; struct filedesc *fdp; struct vnode *cdir, *rdir; int error; if (disablecwd) return (ENODEV); if (buflen < 2) return (EINVAL); if (buflen > MAXPATHLEN) buflen = MAXPATHLEN; tmpbuf = malloc(buflen, M_TEMP, M_WAITOK); fdp = td->td_proc->p_fd; FILEDESC_SLOCK(fdp); cdir = fdp->fd_cdir; VREF(cdir); rdir = fdp->fd_rdir; VREF(rdir); FILEDESC_SUNLOCK(fdp); error = vn_fullpath1(td, cdir, rdir, tmpbuf, &bp, buflen); vrele(rdir); vrele(cdir); if (!error) { if (bufseg == UIO_SYSSPACE) bcopy(bp, buf, strlen(bp) + 1); else error = copyout(bp, buf, strlen(bp) + 1); #ifdef KTRACE if (KTRPOINT(curthread, KTR_NAMEI)) ktrnamei(bp); #endif } free(tmpbuf, M_TEMP); return (error); } /* * Thus begins the fullpath magic. */ #undef STATNODE #define STATNODE(name, descr) \ static u_int name; \ SYSCTL_UINT(_vfs_cache, OID_AUTO, name, CTLFLAG_RD, &name, 0, descr) static int disablefullpath; SYSCTL_INT(_debug, OID_AUTO, disablefullpath, CTLFLAG_RW, &disablefullpath, 0, "Disable the vn_fullpath function"); /* These count for kern___getcwd(), too. */ STATNODE(numfullpathcalls, "Number of fullpath search calls"); STATNODE(numfullpathfail1, "Number of fullpath search errors (ENOTDIR)"); STATNODE(numfullpathfail2, "Number of fullpath search errors (VOP_VPTOCNP failures)"); STATNODE(numfullpathfail4, "Number of fullpath search errors (ENOMEM)"); STATNODE(numfullpathfound, "Number of successful fullpath calls"); /* * Retrieve the full filesystem path that correspond to a vnode from the name * cache (if available) */ int vn_fullpath(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) { char *buf; struct filedesc *fdp; struct vnode *rdir; int error; if (disablefullpath) return (ENODEV); if (vn == NULL) return (EINVAL); buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); fdp = td->td_proc->p_fd; FILEDESC_SLOCK(fdp); rdir = fdp->fd_rdir; VREF(rdir); FILEDESC_SUNLOCK(fdp); error = vn_fullpath1(td, vn, rdir, buf, retbuf, MAXPATHLEN); vrele(rdir); if (!error) *freebuf = buf; else free(buf, M_TEMP); return (error); } /* * This function is similar to vn_fullpath, but it attempts to lookup the * pathname relative to the global root mount point. This is required for the * auditing sub-system, as audited pathnames must be absolute, relative to the * global root mount point. */ int vn_fullpath_global(struct thread *td, struct vnode *vn, char **retbuf, char **freebuf) { char *buf; int error; if (disablefullpath) return (ENODEV); if (vn == NULL) return (EINVAL); buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); error = vn_fullpath1(td, vn, rootvnode, buf, retbuf, MAXPATHLEN); if (!error) *freebuf = buf; else free(buf, M_TEMP); return (error); } int vn_vptocnp(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) { int error; CACHE_RLOCK(); error = vn_vptocnp_locked(vp, cred, buf, buflen); if (error == 0) CACHE_RUNLOCK(); return (error); } static int vn_vptocnp_locked(struct vnode **vp, struct ucred *cred, char *buf, u_int *buflen) { struct vnode *dvp; struct namecache *ncp; int error; TAILQ_FOREACH(ncp, &((*vp)->v_cache_dst), nc_dst) { if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) break; } if (ncp != NULL) { if (*buflen < ncp->nc_nlen) { CACHE_RUNLOCK(); vrele(*vp); numfullpathfail4++; error = ENOMEM; SDT_PROBE(vfs, namecache, fullpath, return, error, vp, NULL, 0, 0); return (error); } *buflen -= ncp->nc_nlen; memcpy(buf + *buflen, nc_get_name(ncp), ncp->nc_nlen); SDT_PROBE(vfs, namecache, fullpath, hit, ncp->nc_dvp, nc_get_name(ncp), vp, 0, 0); dvp = *vp; *vp = ncp->nc_dvp; vref(*vp); CACHE_RUNLOCK(); vrele(dvp); CACHE_RLOCK(); return (0); } SDT_PROBE(vfs, namecache, fullpath, miss, vp, 0, 0, 0, 0); CACHE_RUNLOCK(); vn_lock(*vp, LK_SHARED | LK_RETRY); error = VOP_VPTOCNP(*vp, &dvp, cred, buf, buflen); vput(*vp); if (error) { numfullpathfail2++; SDT_PROBE(vfs, namecache, fullpath, return, error, vp, NULL, 0, 0); return (error); } *vp = dvp; CACHE_RLOCK(); if (dvp->v_iflag & VI_DOOMED) { /* forced unmount */ CACHE_RUNLOCK(); vrele(dvp); error = ENOENT; SDT_PROBE(vfs, namecache, fullpath, return, error, vp, NULL, 0, 0); return (error); } /* * *vp has its use count incremented still. */ return (0); } /* * The magic behind kern___getcwd() and vn_fullpath(). */ static int vn_fullpath1(struct thread *td, struct vnode *vp, struct vnode *rdir, char *buf, char **retbuf, u_int buflen) { int error, slash_prefixed; #ifdef KDTRACE_HOOKS struct vnode *startvp = vp; #endif struct vnode *vp1; buflen--; buf[buflen] = '\0'; error = 0; slash_prefixed = 0; SDT_PROBE(vfs, namecache, fullpath, entry, vp, 0, 0, 0, 0); numfullpathcalls++; vref(vp); CACHE_RLOCK(); if (vp->v_type != VDIR) { error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); if (error) return (error); if (buflen == 0) { CACHE_RUNLOCK(); vrele(vp); return (ENOMEM); } buf[--buflen] = '/'; slash_prefixed = 1; } while (vp != rdir && vp != rootvnode) { if (vp->v_vflag & VV_ROOT) { if (vp->v_iflag & VI_DOOMED) { /* forced unmount */ CACHE_RUNLOCK(); vrele(vp); error = ENOENT; SDT_PROBE(vfs, namecache, fullpath, return, error, vp, NULL, 0, 0); break; } vp1 = vp->v_mount->mnt_vnodecovered; vref(vp1); CACHE_RUNLOCK(); vrele(vp); vp = vp1; CACHE_RLOCK(); continue; } if (vp->v_type != VDIR) { CACHE_RUNLOCK(); vrele(vp); numfullpathfail1++; error = ENOTDIR; SDT_PROBE(vfs, namecache, fullpath, return, error, vp, NULL, 0, 0); break; } error = vn_vptocnp_locked(&vp, td->td_ucred, buf, &buflen); if (error) break; if (buflen == 0) { CACHE_RUNLOCK(); vrele(vp); error = ENOMEM; SDT_PROBE(vfs, namecache, fullpath, return, error, startvp, NULL, 0, 0); break; } buf[--buflen] = '/'; slash_prefixed = 1; } if (error) return (error); if (!slash_prefixed) { if (buflen == 0) { CACHE_RUNLOCK(); vrele(vp); numfullpathfail4++; SDT_PROBE(vfs, namecache, fullpath, return, ENOMEM, startvp, NULL, 0, 0); return (ENOMEM); } buf[--buflen] = '/'; } numfullpathfound++; CACHE_RUNLOCK(); vrele(vp); SDT_PROBE(vfs, namecache, fullpath, return, 0, startvp, buf + buflen, 0, 0); *retbuf = buf + buflen; return (0); } struct vnode * vn_dir_dd_ino(struct vnode *vp) { struct namecache *ncp; struct vnode *ddvp; ASSERT_VOP_LOCKED(vp, "vn_dir_dd_ino"); CACHE_RLOCK(); TAILQ_FOREACH(ncp, &(vp->v_cache_dst), nc_dst) { if ((ncp->nc_flag & NCF_ISDOTDOT) != 0) continue; ddvp = ncp->nc_dvp; VI_LOCK(ddvp); CACHE_RUNLOCK(); if (vget(ddvp, LK_INTERLOCK | LK_SHARED | LK_NOWAIT, curthread)) return (NULL); return (ddvp); } CACHE_RUNLOCK(); return (NULL); } int vn_commname(struct vnode *vp, char *buf, u_int buflen) { struct namecache *ncp; int l; CACHE_RLOCK(); TAILQ_FOREACH(ncp, &vp->v_cache_dst, nc_dst) if ((ncp->nc_flag & NCF_ISDOTDOT) == 0) break; if (ncp == NULL) { CACHE_RUNLOCK(); return (ENOENT); } l = min(ncp->nc_nlen, buflen - 1); memcpy(buf, nc_get_name(ncp), l); CACHE_RUNLOCK(); buf[l] = '\0'; return (0); } /* ABI compat shims for old kernel modules. */ #undef cache_enter void cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp); void cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) { cache_enter_time(dvp, vp, cnp, NULL, NULL); } /* * This function updates path string to vnode's full global path * and checks the size of the new path string against the pathlen argument. * * Requires a locked, referenced vnode and GIANT lock held. * Vnode is re-locked on success or ENODEV, otherwise unlocked. * * If sysctl debug.disablefullpath is set, ENODEV is returned, * vnode is left locked and path remain untouched. * * If vp is a directory, the call to vn_fullpath_global() always succeeds * because it falls back to the ".." lookup if the namecache lookup fails. */ int vn_path_to_global_path(struct thread *td, struct vnode *vp, char *path, u_int pathlen) { struct nameidata nd; struct vnode *vp1; char *rpath, *fbuf; int error; ASSERT_VOP_ELOCKED(vp, __func__); /* Return ENODEV if sysctl debug.disablefullpath==1 */ if (disablefullpath) return (ENODEV); /* Construct global filesystem path from vp. */ VOP_UNLOCK(vp, 0); error = vn_fullpath_global(td, vp, &rpath, &fbuf); if (error != 0) { vrele(vp); return (error); } if (strlen(rpath) >= pathlen) { vrele(vp); error = ENAMETOOLONG; goto out; } /* * Re-lookup the vnode by path to detect a possible rename. * As a side effect, the vnode is relocked. * If vnode was renamed, return ENOENT. */ NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, UIO_SYSSPACE, path, td); error = namei(&nd); if (error != 0) { vrele(vp); goto out; } NDFREE(&nd, NDF_ONLY_PNBUF); vp1 = nd.ni_vp; vrele(vp); if (vp1 == vp) strcpy(path, rpath); else { vput(vp1); error = ENOENT; } out: free(fbuf, M_TEMP); return (error); }