/* $NetBSD: vfs_cache.c,v 1.88 2011/06/12 03:35:56 rmind Exp $ */ /*- * Copyright (c) 2008 The NetBSD Foundation, Inc. * All rights reserved. * * 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. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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. */ /* * Copyright (c) 1989, 1993 * The Regents of the University of California. All rights reserved. * * 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. * 3. 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 8.3 (Berkeley) 8/22/94 */ #include __KERNEL_RCSID(0, "$NetBSD: vfs_cache.c,v 1.88 2011/06/12 03:35:56 rmind Exp $"); #include "opt_ddb.h" #include "opt_revcache.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define NAMECACHE_ENTER_REVERSE /* * 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 (dvp, name) where dvp refers to the directory * containing name. * * For simplicity (and economy of storage), names longer than * a maximum length of NCHNAMLEN are not cached; they occur * infrequently in any case, and are almost never of interest. * * 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. * The entry is dropped also when it was not possible to lock * the cached vnode, either because vget() failed or the generation * number has changed while waiting for the lock. */ /* * Per-cpu namecache data. */ struct nchcpu { kmutex_t cpu_lock; struct nchstats cpu_stats; }; /* * Structures associated with name cacheing. */ LIST_HEAD(nchashhead, namecache) *nchashtbl; u_long nchash; /* size of hash table - 1 */ #define NCHASH(cnp, dvp) \ (((cnp)->cn_hash ^ ((uintptr_t)(dvp) >> 3)) & nchash) LIST_HEAD(ncvhashhead, namecache) *ncvhashtbl; u_long ncvhash; /* size of hash table - 1 */ #define NCVHASH(vp) (((uintptr_t)(vp) >> 3) & ncvhash) long numcache; /* number of cache entries allocated */ static u_int cache_gcpend; /* number of entries pending GC */ static void *cache_gcqueue; /* garbage collection queue */ TAILQ_HEAD(, namecache) nclruhead = /* LRU chain */ TAILQ_HEAD_INITIALIZER(nclruhead); #define COUNT(c,x) (c.x++) struct nchstats nchstats; /* cache effectiveness statistics */ static pool_cache_t namecache_cache; int cache_lowat = 95; int cache_hiwat = 98; int cache_hottime = 5; /* number of seconds */ int doingcache = 1; /* 1 => enable the cache */ static struct evcnt cache_ev_scan; static struct evcnt cache_ev_gc; static struct evcnt cache_ev_over; static struct evcnt cache_ev_under; static struct evcnt cache_ev_forced; /* A single lock to serialize modifications. */ static kmutex_t *namecache_lock; static void cache_invalidate(struct namecache *); static inline struct namecache *cache_lookup_entry( const struct vnode *, const struct componentname *); static void cache_thread(void *); static void cache_invalidate(struct namecache *); static void cache_disassociate(struct namecache *); static void cache_reclaim(void); static int cache_ctor(void *, void *, int); static void cache_dtor(void *, void *); /* * Invalidate a cache entry and enqueue it for garbage collection. */ static void cache_invalidate(struct namecache *ncp) { void *head; KASSERT(mutex_owned(&ncp->nc_lock)); if (ncp->nc_dvp != NULL) { ncp->nc_vp = NULL; ncp->nc_dvp = NULL; do { head = cache_gcqueue; ncp->nc_gcqueue = head; } while (atomic_cas_ptr(&cache_gcqueue, head, ncp) != head); atomic_inc_uint(&cache_gcpend); } } /* * Disassociate a namecache entry from any vnodes it is attached to, * and remove from the global LRU list. */ static void cache_disassociate(struct namecache *ncp) { KASSERT(mutex_owned(namecache_lock)); KASSERT(ncp->nc_dvp == NULL); if (ncp->nc_lru.tqe_prev != NULL) { TAILQ_REMOVE(&nclruhead, ncp, nc_lru); ncp->nc_lru.tqe_prev = NULL; } if (ncp->nc_vhash.le_prev != NULL) { LIST_REMOVE(ncp, nc_vhash); ncp->nc_vhash.le_prev = NULL; } if (ncp->nc_vlist.le_prev != NULL) { LIST_REMOVE(ncp, nc_vlist); ncp->nc_vlist.le_prev = NULL; } if (ncp->nc_dvlist.le_prev != NULL) { LIST_REMOVE(ncp, nc_dvlist); ncp->nc_dvlist.le_prev = NULL; } } /* * Lock all CPUs to prevent any cache lookup activity. Conceptually, * this locks out all "readers". */ static void cache_lock_cpus(void) { CPU_INFO_ITERATOR cii; struct cpu_info *ci; struct nchcpu *cpup; long *s, *d, *m; for (CPU_INFO_FOREACH(cii, ci)) { cpup = ci->ci_data.cpu_nch; mutex_enter(&cpup->cpu_lock); /* Collate statistics. */ d = (long *)&nchstats; s = (long *)&cpup->cpu_stats; m = s + sizeof(nchstats) / sizeof(long); for (; s < m; s++, d++) { *d += *s; *s = 0; } } } /* * Release all CPU locks. */ static void cache_unlock_cpus(void) { CPU_INFO_ITERATOR cii; struct cpu_info *ci; struct nchcpu *cpup; for (CPU_INFO_FOREACH(cii, ci)) { cpup = ci->ci_data.cpu_nch; mutex_exit(&cpup->cpu_lock); } } /* * Find a single cache entry and return it locked. 'namecache_lock' or * at least one of the per-CPU locks must be held. */ static struct namecache * cache_lookup_entry(const struct vnode *dvp, const struct componentname *cnp) { struct nchashhead *ncpp; struct namecache *ncp; KASSERT(dvp != NULL); ncpp = &nchashtbl[NCHASH(cnp, dvp)]; LIST_FOREACH(ncp, ncpp, nc_hash) { if (ncp->nc_dvp != dvp || ncp->nc_nlen != cnp->cn_namelen || memcmp(ncp->nc_name, cnp->cn_nameptr, (u_int)ncp->nc_nlen)) continue; mutex_enter(&ncp->nc_lock); if (__predict_true(ncp->nc_dvp == dvp)) { ncp->nc_hittime = hardclock_ticks; return ncp; } /* Raced: entry has been nullified. */ mutex_exit(&ncp->nc_lock); } return NULL; } /* * Look for a the name in the cache. We don't do this * if the segment name is long, simply so the cache can avoid * holding long names (which would either waste space, or * add greatly to the complexity). * * Lookup is called with ni_dvp pointing to the directory to search, * ni_ptr pointing to the name of the entry being sought, ni_namelen * tells the length of the name, and ni_hash contains a hash of * the name. If the lookup succeeds, the vnode is locked, stored in ni_vp * and a status of zero is returned. If the locking fails for whatever * reason, the vnode is unlocked and the error is returned to caller. * 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 -1 * is returned. */ int cache_lookup(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) { struct namecache *ncp; struct vnode *vp; struct nchcpu *cpup; int error; if (__predict_false(!doingcache)) { cnp->cn_flags &= ~MAKEENTRY; *vpp = NULL; return -1; } cpup = curcpu()->ci_data.cpu_nch; mutex_enter(&cpup->cpu_lock); if (__predict_false(cnp->cn_namelen > NCHNAMLEN)) { COUNT(cpup->cpu_stats, ncs_long); cnp->cn_flags &= ~MAKEENTRY; mutex_exit(&cpup->cpu_lock); *vpp = NULL; return -1; } ncp = cache_lookup_entry(dvp, cnp); if (__predict_false(ncp == NULL)) { COUNT(cpup->cpu_stats, ncs_miss); mutex_exit(&cpup->cpu_lock); *vpp = NULL; return -1; } if ((cnp->cn_flags & MAKEENTRY) == 0) { COUNT(cpup->cpu_stats, ncs_badhits); /* * Last component and we are renaming or deleting, * the cache entry is invalid, or otherwise don't * want cache entry to exist. */ cache_invalidate(ncp); mutex_exit(&ncp->nc_lock); mutex_exit(&cpup->cpu_lock); *vpp = NULL; return -1; } else if (ncp->nc_vp == NULL) { /* * Restore the ISWHITEOUT flag saved earlier. */ KASSERT((ncp->nc_flags & ~ISWHITEOUT) == 0); cnp->cn_flags |= ncp->nc_flags; if (__predict_true(cnp->cn_nameiop != CREATE || (cnp->cn_flags & ISLASTCN) == 0)) { COUNT(cpup->cpu_stats, ncs_neghits); mutex_exit(&ncp->nc_lock); mutex_exit(&cpup->cpu_lock); return ENOENT; } else { COUNT(cpup->cpu_stats, ncs_badhits); /* * Last component and we are renaming or * deleting, the cache entry is invalid, * or otherwise don't want cache entry to * exist. */ cache_invalidate(ncp); mutex_exit(&ncp->nc_lock); mutex_exit(&cpup->cpu_lock); *vpp = NULL; return -1; } } vp = ncp->nc_vp; if (vtryget(vp)) { mutex_exit(&ncp->nc_lock); mutex_exit(&cpup->cpu_lock); } else { mutex_enter(vp->v_interlock); mutex_exit(&ncp->nc_lock); mutex_exit(&cpup->cpu_lock); error = vget(vp, LK_NOWAIT); if (error) { KASSERT(error == EBUSY); /* * This vnode is being cleaned out. * XXX badhits? */ COUNT(cpup->cpu_stats, ncs_falsehits); *vpp = NULL; return -1; } } #ifdef DEBUG /* * since we released nb->nb_lock, * we can't use this pointer any more. */ ncp = NULL; #endif /* DEBUG */ if (vp == dvp) { /* lookup on "." */ error = 0; } else if (cnp->cn_flags & ISDOTDOT) { VOP_UNLOCK(dvp); error = vn_lock(vp, LK_EXCLUSIVE); vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY); } else { error = vn_lock(vp, LK_EXCLUSIVE); } /* * Check that the lock succeeded. */ if (error) { /* Unlocked, but only for stats. */ COUNT(cpup->cpu_stats, ncs_badhits); vrele(vp); *vpp = NULL; return -1; } /* Unlocked, but only for stats. */ COUNT(cpup->cpu_stats, ncs_goodhits); *vpp = vp; return 0; } int cache_lookup_raw(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp) { struct namecache *ncp; struct vnode *vp; struct nchcpu *cpup; int error; if (__predict_false(!doingcache)) { cnp->cn_flags &= ~MAKEENTRY; *vpp = NULL; return (-1); } cpup = curcpu()->ci_data.cpu_nch; mutex_enter(&cpup->cpu_lock); if (__predict_false(cnp->cn_namelen > NCHNAMLEN)) { COUNT(cpup->cpu_stats, ncs_long); cnp->cn_flags &= ~MAKEENTRY; mutex_exit(&cpup->cpu_lock); *vpp = NULL; return -1; } ncp = cache_lookup_entry(dvp, cnp); if (__predict_false(ncp == NULL)) { COUNT(cpup->cpu_stats, ncs_miss); mutex_exit(&cpup->cpu_lock); *vpp = NULL; return -1; } vp = ncp->nc_vp; if (vp == NULL) { /* * Restore the ISWHITEOUT flag saved earlier. */ KASSERT((ncp->nc_flags & ~ISWHITEOUT) == 0); cnp->cn_flags |= ncp->nc_flags; COUNT(cpup->cpu_stats, ncs_neghits); mutex_exit(&ncp->nc_lock); mutex_exit(&cpup->cpu_lock); return ENOENT; } if (vtryget(vp)) { mutex_exit(&ncp->nc_lock); mutex_exit(&cpup->cpu_lock); } else { mutex_enter(vp->v_interlock); mutex_exit(&ncp->nc_lock); mutex_exit(&cpup->cpu_lock); error = vget(vp, LK_NOWAIT); if (error) { KASSERT(error == EBUSY); /* * This vnode is being cleaned out. * XXX badhits? */ COUNT(cpup->cpu_stats, ncs_falsehits); *vpp = NULL; return -1; } } /* Unlocked, but only for stats. */ COUNT(cpup->cpu_stats, ncs_goodhits); /* XXX can be "badhits" */ *vpp = vp; return 0; } /* * Scan cache looking for name of directory entry pointing at vp. * * If the lookup succeeds the vnode is referenced and stored in dvpp. * * If bufp is non-NULL, also place the name in the buffer which starts * at bufp, immediately before *bpp, and move bpp backwards to point * at the start of it. (Yes, this is a little baroque, but it's done * this way to cater to the whims of getcwd). * * Returns 0 on success, -1 on cache miss, positive errno on failure. */ int cache_revlookup(struct vnode *vp, struct vnode **dvpp, char **bpp, char *bufp) { struct namecache *ncp; struct vnode *dvp; struct ncvhashhead *nvcpp; char *bp; int error, nlen; if (!doingcache) goto out; nvcpp = &ncvhashtbl[NCVHASH(vp)]; mutex_enter(namecache_lock); LIST_FOREACH(ncp, nvcpp, nc_vhash) { mutex_enter(&ncp->nc_lock); if (ncp->nc_vp == vp && (dvp = ncp->nc_dvp) != NULL && dvp != vp) { /* avoid pesky . entries.. */ #ifdef DIAGNOSTIC if (ncp->nc_nlen == 1 && ncp->nc_name[0] == '.') panic("cache_revlookup: found entry for ."); if (ncp->nc_nlen == 2 && ncp->nc_name[0] == '.' && ncp->nc_name[1] == '.') panic("cache_revlookup: found entry for .."); #endif COUNT(nchstats, ncs_revhits); nlen = ncp->nc_nlen; if (bufp) { bp = *bpp; bp -= nlen; if (bp <= bufp) { *dvpp = NULL; mutex_exit(&ncp->nc_lock); mutex_exit(namecache_lock); return (ERANGE); } memcpy(bp, ncp->nc_name, nlen); *bpp = bp; } if (vtryget(dvp)) { mutex_exit(&ncp->nc_lock); mutex_exit(namecache_lock); } else { mutex_enter(dvp->v_interlock); mutex_exit(&ncp->nc_lock); mutex_exit(namecache_lock); error = vget(dvp, LK_NOWAIT); if (error) { KASSERT(error == EBUSY); if (bufp) (*bpp) += nlen; *dvpp = NULL; return -1; } } *dvpp = dvp; return (0); } mutex_exit(&ncp->nc_lock); } COUNT(nchstats, ncs_revmiss); mutex_exit(namecache_lock); out: *dvpp = NULL; return (-1); } /* * Add an entry to the cache */ void cache_enter(struct vnode *dvp, struct vnode *vp, struct componentname *cnp) { struct namecache *ncp; struct namecache *oncp; struct nchashhead *ncpp; struct ncvhashhead *nvcpp; #ifdef DIAGNOSTIC if (cnp->cn_namelen > NCHNAMLEN) panic("cache_enter: name too long"); #endif if (!doingcache) return; if (numcache > desiredvnodes) { mutex_enter(namecache_lock); cache_ev_forced.ev_count++; cache_reclaim(); mutex_exit(namecache_lock); } ncp = pool_cache_get(namecache_cache, PR_WAITOK); mutex_enter(namecache_lock); numcache++; /* * Concurrent lookups in the same directory may race for a * cache entry. if there's a duplicated entry, free it. */ oncp = cache_lookup_entry(dvp, cnp); if (oncp) { cache_invalidate(oncp); mutex_exit(&oncp->nc_lock); } /* Grab the vnode we just found. */ mutex_enter(&ncp->nc_lock); ncp->nc_vp = vp; ncp->nc_flags = 0; ncp->nc_hittime = 0; ncp->nc_gcqueue = NULL; if (vp == NULL) { /* * For negative hits, save the ISWHITEOUT flag so we can * restore it later when the cache entry is used again. */ ncp->nc_flags = cnp->cn_flags & ISWHITEOUT; } /* Fill in cache info. */ ncp->nc_dvp = dvp; LIST_INSERT_HEAD(&dvp->v_dnclist, ncp, nc_dvlist); if (vp) LIST_INSERT_HEAD(&vp->v_nclist, ncp, nc_vlist); else { ncp->nc_vlist.le_prev = NULL; ncp->nc_vlist.le_next = NULL; } ncp->nc_nlen = cnp->cn_namelen; TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru); memcpy(ncp->nc_name, cnp->cn_nameptr, (unsigned)ncp->nc_nlen); ncpp = &nchashtbl[NCHASH(cnp, dvp)]; /* * Flush updates before making visible in table. No need for a * memory barrier on the other side: to see modifications the * list must be followed, meaning a dependent pointer load. * The below is LIST_INSERT_HEAD() inlined, with the memory * barrier included in the correct place. */ if ((ncp->nc_hash.le_next = ncpp->lh_first) != NULL) ncpp->lh_first->nc_hash.le_prev = &ncp->nc_hash.le_next; ncp->nc_hash.le_prev = &ncpp->lh_first; membar_producer(); ncpp->lh_first = ncp; ncp->nc_vhash.le_prev = NULL; ncp->nc_vhash.le_next = NULL; /* * Create reverse-cache entries (used in getcwd) for directories. * (and in linux procfs exe node) */ if (vp != NULL && vp != dvp && #ifndef NAMECACHE_ENTER_REVERSE vp->v_type == VDIR && #endif (ncp->nc_nlen > 2 || (ncp->nc_nlen > 1 && ncp->nc_name[1] != '.') || (/* ncp->nc_nlen > 0 && */ ncp->nc_name[0] != '.'))) { nvcpp = &ncvhashtbl[NCVHASH(vp)]; LIST_INSERT_HEAD(nvcpp, ncp, nc_vhash); } mutex_exit(&ncp->nc_lock); mutex_exit(namecache_lock); } /* * Name cache initialization, from vfs_init() when we are booting */ void nchinit(void) { int error; namecache_cache = pool_cache_init(sizeof(struct namecache), coherency_unit, 0, 0, "ncache", NULL, IPL_NONE, cache_ctor, cache_dtor, NULL); KASSERT(namecache_cache != NULL); namecache_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_NONE); nchashtbl = hashinit(desiredvnodes, HASH_LIST, true, &nchash); ncvhashtbl = #ifdef NAMECACHE_ENTER_REVERSE hashinit(desiredvnodes, HASH_LIST, true, &ncvhash); #else hashinit(desiredvnodes/8, HASH_LIST, true, &ncvhash); #endif error = kthread_create(PRI_VM, KTHREAD_MPSAFE, NULL, cache_thread, NULL, NULL, "cachegc"); if (error != 0) panic("nchinit %d", error); evcnt_attach_dynamic(&cache_ev_scan, EVCNT_TYPE_MISC, NULL, "namecache", "entries scanned"); evcnt_attach_dynamic(&cache_ev_gc, EVCNT_TYPE_MISC, NULL, "namecache", "entries collected"); evcnt_attach_dynamic(&cache_ev_over, EVCNT_TYPE_MISC, NULL, "namecache", "over scan target"); evcnt_attach_dynamic(&cache_ev_under, EVCNT_TYPE_MISC, NULL, "namecache", "under scan target"); evcnt_attach_dynamic(&cache_ev_forced, EVCNT_TYPE_MISC, NULL, "namecache", "forced reclaims"); } static int cache_ctor(void *arg, void *obj, int flag) { struct namecache *ncp; ncp = obj; mutex_init(&ncp->nc_lock, MUTEX_DEFAULT, IPL_NONE); return 0; } static void cache_dtor(void *arg, void *obj) { struct namecache *ncp; ncp = obj; mutex_destroy(&ncp->nc_lock); } /* * Called once for each CPU in the system as attached. */ void cache_cpu_init(struct cpu_info *ci) { struct nchcpu *cpup; size_t sz; sz = roundup2(sizeof(*cpup), coherency_unit) + coherency_unit; cpup = kmem_zalloc(sz, KM_SLEEP); cpup = (void *)roundup2((uintptr_t)cpup, coherency_unit); mutex_init(&cpup->cpu_lock, MUTEX_DEFAULT, IPL_NONE); ci->ci_data.cpu_nch = cpup; } /* * Name cache reinitialization, for when the maximum number of vnodes increases. */ void nchreinit(void) { struct namecache *ncp; struct nchashhead *oldhash1, *hash1; struct ncvhashhead *oldhash2, *hash2; u_long i, oldmask1, oldmask2, mask1, mask2; hash1 = hashinit(desiredvnodes, HASH_LIST, true, &mask1); hash2 = #ifdef NAMECACHE_ENTER_REVERSE hashinit(desiredvnodes, HASH_LIST, true, &mask2); #else hashinit(desiredvnodes/8, HASH_LIST, true, &mask2); #endif mutex_enter(namecache_lock); cache_lock_cpus(); oldhash1 = nchashtbl; oldmask1 = nchash; nchashtbl = hash1; nchash = mask1; oldhash2 = ncvhashtbl; oldmask2 = ncvhash; ncvhashtbl = hash2; ncvhash = mask2; for (i = 0; i <= oldmask1; i++) { while ((ncp = LIST_FIRST(&oldhash1[i])) != NULL) { LIST_REMOVE(ncp, nc_hash); ncp->nc_hash.le_prev = NULL; } } for (i = 0; i <= oldmask2; i++) { while ((ncp = LIST_FIRST(&oldhash2[i])) != NULL) { LIST_REMOVE(ncp, nc_vhash); ncp->nc_vhash.le_prev = NULL; } } cache_unlock_cpus(); mutex_exit(namecache_lock); hashdone(oldhash1, HASH_LIST, oldmask1); hashdone(oldhash2, HASH_LIST, oldmask2); } /* * Cache flush, a particular vnode; called when a vnode is renamed to * hide entries that would now be invalid */ void cache_purge1(struct vnode *vp, const struct componentname *cnp, int flags) { struct namecache *ncp, *ncnext; mutex_enter(namecache_lock); if (flags & PURGE_PARENTS) { for (ncp = LIST_FIRST(&vp->v_nclist); ncp != NULL; ncp = ncnext) { ncnext = LIST_NEXT(ncp, nc_vlist); mutex_enter(&ncp->nc_lock); cache_invalidate(ncp); mutex_exit(&ncp->nc_lock); cache_disassociate(ncp); } } if (flags & PURGE_CHILDREN) { for (ncp = LIST_FIRST(&vp->v_dnclist); ncp != NULL; ncp = ncnext) { ncnext = LIST_NEXT(ncp, nc_dvlist); mutex_enter(&ncp->nc_lock); cache_invalidate(ncp); mutex_exit(&ncp->nc_lock); cache_disassociate(ncp); } } if (cnp != NULL) { ncp = cache_lookup_entry(vp, cnp); if (ncp) { cache_invalidate(ncp); mutex_exit(&ncp->nc_lock); cache_disassociate(ncp); } } mutex_exit(namecache_lock); } /* * Cache flush, a whole filesystem; called when filesys is umounted to * remove entries that would now be invalid. */ void cache_purgevfs(struct mount *mp) { struct namecache *ncp, *nxtcp; mutex_enter(namecache_lock); for (ncp = TAILQ_FIRST(&nclruhead); ncp != NULL; ncp = nxtcp) { nxtcp = TAILQ_NEXT(ncp, nc_lru); mutex_enter(&ncp->nc_lock); if (ncp->nc_dvp != NULL && ncp->nc_dvp->v_mount == mp) { /* Free the resources we had. */ cache_invalidate(ncp); cache_disassociate(ncp); } mutex_exit(&ncp->nc_lock); } cache_reclaim(); mutex_exit(namecache_lock); } /* * Scan global list invalidating entries until we meet a preset target. * Prefer to invalidate entries that have not scored a hit within * cache_hottime seconds. We sort the LRU list only for this routine's * benefit. */ static void cache_prune(int incache, int target) { struct namecache *ncp, *nxtcp, *sentinel; int items, recent, tryharder; KASSERT(mutex_owned(namecache_lock)); items = 0; tryharder = 0; recent = hardclock_ticks - hz * cache_hottime; sentinel = NULL; for (ncp = TAILQ_FIRST(&nclruhead); ncp != NULL; ncp = nxtcp) { if (incache <= target) break; items++; nxtcp = TAILQ_NEXT(ncp, nc_lru); if (ncp->nc_dvp == NULL) continue; if (ncp == sentinel) { /* * If we looped back on ourself, then ignore * recent entries and purge whatever we find. */ tryharder = 1; } if (!tryharder && (ncp->nc_hittime - recent) > 0) { if (sentinel == NULL) sentinel = ncp; TAILQ_REMOVE(&nclruhead, ncp, nc_lru); TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru); continue; } mutex_enter(&ncp->nc_lock); if (ncp->nc_dvp != NULL) { cache_invalidate(ncp); cache_disassociate(ncp); incache--; } mutex_exit(&ncp->nc_lock); } cache_ev_scan.ev_count += items; } /* * Collect dead cache entries from all CPUs and garbage collect. */ static void cache_reclaim(void) { struct namecache *ncp, *next; int items; KASSERT(mutex_owned(namecache_lock)); /* * If the number of extant entries not awaiting garbage collection * exceeds the high water mark, then reclaim stale entries until we * reach our low water mark. */ items = numcache - cache_gcpend; if (items > (uint64_t)desiredvnodes * cache_hiwat / 100) { cache_prune(items, (int)((uint64_t)desiredvnodes * cache_lowat / 100)); cache_ev_over.ev_count++; } else cache_ev_under.ev_count++; /* * Stop forward lookup activity on all CPUs and garbage collect dead * entries. */ cache_lock_cpus(); ncp = cache_gcqueue; cache_gcqueue = NULL; items = cache_gcpend; cache_gcpend = 0; while (ncp != NULL) { next = ncp->nc_gcqueue; cache_disassociate(ncp); KASSERT(ncp->nc_dvp == NULL); if (ncp->nc_hash.le_prev != NULL) { LIST_REMOVE(ncp, nc_hash); ncp->nc_hash.le_prev = NULL; } pool_cache_put(namecache_cache, ncp); ncp = next; } cache_unlock_cpus(); numcache -= items; cache_ev_gc.ev_count += items; } /* * Cache maintainence thread, awakening once per second to: * * => keep number of entries below the high water mark * => sort pseudo-LRU list * => garbage collect dead entries */ static void cache_thread(void *arg) { mutex_enter(namecache_lock); for (;;) { cache_reclaim(); kpause("cachegc", false, hz, namecache_lock); } } #ifdef DDB void namecache_print(struct vnode *vp, void (*pr)(const char *, ...)) { struct vnode *dvp = NULL; struct namecache *ncp; TAILQ_FOREACH(ncp, &nclruhead, nc_lru) { if (ncp->nc_vp == vp && ncp->nc_dvp != NULL) { (*pr)("name %.*s\n", ncp->nc_nlen, ncp->nc_name); dvp = ncp->nc_dvp; } } if (dvp == NULL) { (*pr)("name not found\n"); return; } vp = dvp; TAILQ_FOREACH(ncp, &nclruhead, nc_lru) { if (ncp->nc_vp == vp) { (*pr)("parent %.*s\n", ncp->nc_nlen, ncp->nc_name); } } } #endif