/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License (the "License"). * You may not use this file except in compliance with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * Use is subject to license terms. */ /* Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T */ /* All Rights Reserved */ /* * University Copyright- Copyright (c) 1982, 1986, 1988 * The Regents of the University of California * All Rights Reserved * * University Acknowledgment- Portions of this document are derived from * software developed by the University of California, Berkeley, and its * contributors. */ #pragma ident "%Z%%M% %I% %E% SMI" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Directory name lookup cache. * Based on code originally done by Robert Elz at Melbourne. * * Names found by directory scans are retained in a cache * for future reference. Each hash chain is ordered by LRU * Cache is indexed by hash value obtained from (vp, name) * where the vp refers to the directory containing the name. */ /* * Tunable nc_hashavelen is the average length desired for this chain, from * which the size of the nc_hash table is derived at create time. */ #define NC_HASHAVELEN_DEFAULT 4 int nc_hashavelen = NC_HASHAVELEN_DEFAULT; /* * NC_MOVETOFRONT is the move-to-front threshold: if the hash lookup * depth exceeds this value, we move the looked-up entry to the front of * its hash chain. The idea is to make sure that the most frequently * accessed entries are found most quickly (by keeping them near the * front of their hash chains). */ #define NC_MOVETOFRONT 2 /* * * DNLC_MAX_RELE is used to size an array on the stack when releasing * vnodes. This array is used rather than calling VN_RELE() inline because * all dnlc locks must be dropped by that time in order to avoid a * possible deadlock. This deadlock occurs when the dnlc holds the last * reference to the vnode and so the VOP_INACTIVE vector is called which * can in turn call back into the dnlc. A global array was used but had * many problems: * 1) Actually doesn't have an upper bound on the array size as * entries can be added after starting the purge. * 2) The locking scheme causes a hang. * 3) Caused serialisation on the global lock. * 4) The array was often unnecessarily huge. * * Note the current value 8 allows up to 4 cache entries (to be purged * from each hash chain), before having to cycle around and retry. * This ought to be ample given that nc_hashavelen is typically very small. */ #define DNLC_MAX_RELE 8 /* must be even */ /* * Hash table of name cache entries for fast lookup, dynamically * allocated at startup. */ nc_hash_t *nc_hash; /* * Rotors. Used to select entries on a round-robin basis. */ static nc_hash_t *dnlc_purge_fs1_rotor; static nc_hash_t *dnlc_free_rotor; /* * # of dnlc entries (uninitialized) * * the initial value was chosen as being * a random string of bits, probably not * normally chosen by a systems administrator */ int ncsize = -1; uint32_t dnlc_nentries = 0; /* current number of name cache entries */ static int nc_hashsz; /* size of hash table */ static int nc_hashmask; /* size of hash table minus 1 */ /* * The dnlc_reduce_cache() taskq queue is activated when there are * ncsize name cache entries and it reduces the size down to * dnlc_nentries_low_water, which is by default one hundreth * less (or 99%) of ncsize. */ #define DNLC_LOW_WATER_DIVISOR_DEFAULT 100 uint_t dnlc_low_water_divisor = DNLC_LOW_WATER_DIVISOR_DEFAULT; uint_t dnlc_nentries_low_water; int dnlc_reduce_idle = 1; /* no locking needed */ /* * If dnlc_nentries hits dnlc_max_nentries (twice ncsize) * then this means the dnlc_reduce_cache() taskq is failing to * keep up. In this case we refuse to add new entries to the dnlc * until the taskq catches up. */ uint_t dnlc_max_nentries; /* twice ncsize */ uint64_t dnlc_max_nentries_cnt = 0; /* statistic on times we failed */ /* * Tunable to define when we should just remove items from * the end of the chain. */ #define DNLC_LONG_CHAIN 8 uint_t dnlc_long_chain = DNLC_LONG_CHAIN; /* * ncstats has been deprecated, due to the integer size of the counters * which can easily overflow in the dnlc. * It is maintained (at some expense) for compatability. * The preferred interface is the kstat accessible nc_stats below. */ struct ncstats ncstats; struct nc_stats ncs = { { "hits", KSTAT_DATA_UINT64 }, { "misses", KSTAT_DATA_UINT64 }, { "negative_cache_hits", KSTAT_DATA_UINT64 }, { "enters", KSTAT_DATA_UINT64 }, { "double_enters", KSTAT_DATA_UINT64 }, { "purge_total_entries", KSTAT_DATA_UINT64 }, { "purge_all", KSTAT_DATA_UINT64 }, { "purge_vp", KSTAT_DATA_UINT64 }, { "purge_vfs", KSTAT_DATA_UINT64 }, { "purge_fs1", KSTAT_DATA_UINT64 }, { "pick_free", KSTAT_DATA_UINT64 }, { "pick_heuristic", KSTAT_DATA_UINT64 }, { "pick_last", KSTAT_DATA_UINT64 }, /* directory caching stats */ { "dir_hits", KSTAT_DATA_UINT64 }, { "dir_misses", KSTAT_DATA_UINT64 }, { "dir_cached_current", KSTAT_DATA_UINT64 }, { "dir_entries_cached_current", KSTAT_DATA_UINT64 }, { "dir_cached_total", KSTAT_DATA_UINT64 }, { "dir_start_no_memory", KSTAT_DATA_UINT64 }, { "dir_add_no_memory", KSTAT_DATA_UINT64 }, { "dir_add_abort", KSTAT_DATA_UINT64 }, { "dir_add_max", KSTAT_DATA_UINT64 }, { "dir_remove_entry_fail", KSTAT_DATA_UINT64 }, { "dir_remove_space_fail", KSTAT_DATA_UINT64 }, { "dir_update_fail", KSTAT_DATA_UINT64 }, { "dir_fini_purge", KSTAT_DATA_UINT64 }, { "dir_reclaim_last", KSTAT_DATA_UINT64 }, { "dir_reclaim_any", KSTAT_DATA_UINT64 }, }; static int doingcache = 1; vnode_t negative_cache_vnode; /* * Insert entry at the front of the queue */ #define nc_inshash(ncp, hp) \ { \ (ncp)->hash_next = (hp)->hash_next; \ (ncp)->hash_prev = (ncache_t *)(hp); \ (hp)->hash_next->hash_prev = (ncp); \ (hp)->hash_next = (ncp); \ } /* * Remove entry from hash queue */ #define nc_rmhash(ncp) \ { \ (ncp)->hash_prev->hash_next = (ncp)->hash_next; \ (ncp)->hash_next->hash_prev = (ncp)->hash_prev; \ (ncp)->hash_prev = NULL; \ (ncp)->hash_next = NULL; \ } /* * Free an entry. */ #define dnlc_free(ncp) \ { \ kmem_free((ncp), sizeof (ncache_t) + (ncp)->namlen); \ atomic_add_32(&dnlc_nentries, -1); \ } /* * Cached directory info. * ====================== */ /* * Cached directory free space hash function. * Needs the free space handle and the dcp to get the hash table size * Returns the hash index. */ #define DDFHASH(handle, dcp) ((handle >> 2) & (dcp)->dc_fhash_mask) /* * Cached directory name entry hash function. * Uses the name and returns in the input arguments the hash and the name * length. */ #define DNLC_DIR_HASH(name, hash, namelen) \ { \ char Xc, *Xcp; \ hash = *name; \ for (Xcp = (name + 1); (Xc = *Xcp) != 0; Xcp++) \ hash = (hash << 4) + hash + Xc; \ ASSERT((Xcp - (name)) <= ((1 << NBBY) - 1)); \ namelen = Xcp - (name); \ } /* special dircache_t pointer to indicate error should be returned */ /* * The anchor directory cache pointer can contain 3 types of values, * 1) NULL: No directory cache * 2) DC_RET_LOW_MEM (-1): There was a directory cache that found to be * too big or a memory shortage occurred. This value remains in the * pointer until a dnlc_dir_start() which returns the a DNOMEM error. * This is kludgy but efficient and only visible in this source file. * 3) A valid cache pointer. */ #define DC_RET_LOW_MEM (dircache_t *)1 #define VALID_DIR_CACHE(dcp) ((dircache_t *)(dcp) > DC_RET_LOW_MEM) /* Tunables */ uint_t dnlc_dir_enable = 1; /* disable caching directories by setting to 0 */ uint_t dnlc_dir_min_size = 40; /* min no of directory entries before caching */ uint_t dnlc_dir_max_size = UINT_MAX; /* ditto maximum */ uint_t dnlc_dir_hash_size_shift = 3; /* 8 entries per hash bucket */ uint_t dnlc_dir_min_reclaim = 350000; /* approx 1MB of dcentrys */ /* * dnlc_dir_hash_resize_shift determines when the hash tables * get re-adjusted due to growth or shrinkage * - currently 2 indicating that there can be at most 4 * times or at least one quarter the number of entries * before hash table readjustment. Note that with * dnlc_dir_hash_size_shift above set at 3 this would * mean readjustment would occur if the average number * of entries went above 32 or below 2 */ uint_t dnlc_dir_hash_resize_shift = 2; /* readjust rate */ static kmem_cache_t *dnlc_dir_space_cache; /* free space entry cache */ static dchead_t dc_head; /* anchor of cached directories */ /* Prototypes */ static ncache_t *dnlc_get(uchar_t namlen); static ncache_t *dnlc_search(vnode_t *dp, char *name, uchar_t namlen, int hash); static void dnlc_reduce_cache(void *unused); static void dnlc_dir_reclaim(void *unused); static void dnlc_dir_abort(dircache_t *dcp); static void dnlc_dir_adjust_fhash(dircache_t *dcp); static void dnlc_dir_adjust_nhash(dircache_t *dcp); /* * Initialize the directory cache. */ void dnlc_init() { nc_hash_t *hp; kstat_t *ksp; int i; /* * Set up the size of the dnlc (ncsize) and its low water mark. */ if (ncsize == -1) { /* calculate a reasonable size for the low water */ dnlc_nentries_low_water = 4 * (v.v_proc + maxusers) + 320; ncsize = dnlc_nentries_low_water + (dnlc_nentries_low_water / dnlc_low_water_divisor); } else { /* don't change the user specified ncsize */ dnlc_nentries_low_water = ncsize - (ncsize / dnlc_low_water_divisor); } if (ncsize <= 0) { doingcache = 0; dnlc_dir_enable = 0; /* also disable directory caching */ ncsize = 0; cmn_err(CE_NOTE, "name cache (dnlc) disabled"); return; } dnlc_max_nentries = ncsize * 2; /* * Initialise the hash table. * Compute hash size rounding to the next power of two. */ nc_hashsz = ncsize / nc_hashavelen; nc_hashsz = 1 << highbit(nc_hashsz); nc_hashmask = nc_hashsz - 1; nc_hash = kmem_zalloc(nc_hashsz * sizeof (*nc_hash), KM_SLEEP); for (i = 0; i < nc_hashsz; i++) { hp = (nc_hash_t *)&nc_hash[i]; mutex_init(&hp->hash_lock, NULL, MUTEX_DEFAULT, NULL); hp->hash_next = (ncache_t *)hp; hp->hash_prev = (ncache_t *)hp; } /* * Initialize rotors */ dnlc_free_rotor = dnlc_purge_fs1_rotor = &nc_hash[0]; /* * Set up the directory caching to use kmem_cache_alloc * for its free space entries so that we can get a callback * when the system is short on memory, to allow us to free * up some memory. we don't use the constructor/deconstructor * functions. */ dnlc_dir_space_cache = kmem_cache_create("dnlc_space_cache", sizeof (dcfree_t), 0, NULL, NULL, dnlc_dir_reclaim, NULL, NULL, 0); /* * Initialise the head of the cached directory structures */ mutex_init(&dc_head.dch_lock, NULL, MUTEX_DEFAULT, NULL); dc_head.dch_next = (dircache_t *)&dc_head; dc_head.dch_prev = (dircache_t *)&dc_head; /* * Initialise the reference count of the negative cache vnode to 1 * so that it never goes away (VOP_INACTIVE isn't called on it). */ negative_cache_vnode.v_count = 1; /* * Initialise kstats - both the old compatability raw kind and * the more extensive named stats. */ ksp = kstat_create("unix", 0, "ncstats", "misc", KSTAT_TYPE_RAW, sizeof (struct ncstats), KSTAT_FLAG_VIRTUAL); if (ksp) { ksp->ks_data = (void *) &ncstats; kstat_install(ksp); } ksp = kstat_create("unix", 0, "dnlcstats", "misc", KSTAT_TYPE_NAMED, sizeof (ncs) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL); if (ksp) { ksp->ks_data = (void *) &ncs; kstat_install(ksp); } } /* * Add a name to the directory cache. */ void dnlc_enter(vnode_t *dp, char *name, vnode_t *vp) { ncache_t *ncp; nc_hash_t *hp; uchar_t namlen; int hash; TRACE_0(TR_FAC_NFS, TR_DNLC_ENTER_START, "dnlc_enter_start:"); if (!doingcache) { TRACE_2(TR_FAC_NFS, TR_DNLC_ENTER_END, "dnlc_enter_end:(%S) %d", "not caching", 0); return; } /* * Get a new dnlc entry. Assume the entry won't be in the cache * and initialize it now */ DNLCHASH(name, dp, hash, namlen); if ((ncp = dnlc_get(namlen)) == NULL) return; ncp->dp = dp; VN_HOLD(dp); ncp->vp = vp; VN_HOLD(vp); bcopy(name, ncp->name, namlen + 1); /* name and null */ ncp->hash = hash; hp = &nc_hash[hash & nc_hashmask]; mutex_enter(&hp->hash_lock); if (dnlc_search(dp, name, namlen, hash) != NULL) { mutex_exit(&hp->hash_lock); ncstats.dbl_enters++; ncs.ncs_dbl_enters.value.ui64++; VN_RELE(dp); VN_RELE(vp); dnlc_free(ncp); /* crfree done here */ TRACE_2(TR_FAC_NFS, TR_DNLC_ENTER_END, "dnlc_enter_end:(%S) %d", "dbl enter", ncstats.dbl_enters); return; } /* * Insert back into the hash chain. */ nc_inshash(ncp, hp); mutex_exit(&hp->hash_lock); ncstats.enters++; ncs.ncs_enters.value.ui64++; TRACE_2(TR_FAC_NFS, TR_DNLC_ENTER_END, "dnlc_enter_end:(%S) %d", "done", ncstats.enters); } /* * Add a name to the directory cache. * * This function is basically identical with * dnlc_enter(). The difference is that when the * desired dnlc entry is found, the vnode in the * ncache is compared with the vnode passed in. * * If they are not equal then the ncache is * updated with the passed in vnode. Otherwise * it just frees up the newly allocated dnlc entry. */ void dnlc_update(vnode_t *dp, char *name, vnode_t *vp) { ncache_t *ncp; ncache_t *tcp; vnode_t *tvp; nc_hash_t *hp; int hash; uchar_t namlen; TRACE_0(TR_FAC_NFS, TR_DNLC_ENTER_START, "dnlc_update_start:"); if (!doingcache) { TRACE_2(TR_FAC_NFS, TR_DNLC_ENTER_END, "dnlc_update_end:(%S) %d", "not caching", 0); return; } /* * Get a new dnlc entry and initialize it now. * If we fail to get a new entry, call dnlc_remove() to purge * any existing dnlc entry including negative cache (DNLC_NO_VNODE) * entry. * Failure to clear an existing entry could result in false dnlc * lookup (negative/stale entry). */ DNLCHASH(name, dp, hash, namlen); if ((ncp = dnlc_get(namlen)) == NULL) { dnlc_remove(dp, name); return; } ncp->dp = dp; VN_HOLD(dp); ncp->vp = vp; VN_HOLD(vp); bcopy(name, ncp->name, namlen + 1); /* name and null */ ncp->hash = hash; hp = &nc_hash[hash & nc_hashmask]; mutex_enter(&hp->hash_lock); if ((tcp = dnlc_search(dp, name, namlen, hash)) != NULL) { if (tcp->vp != vp) { tvp = tcp->vp; tcp->vp = vp; mutex_exit(&hp->hash_lock); VN_RELE(tvp); ncstats.enters++; ncs.ncs_enters.value.ui64++; TRACE_2(TR_FAC_NFS, TR_DNLC_ENTER_END, "dnlc_update_end:(%S) %d", "done", ncstats.enters); } else { mutex_exit(&hp->hash_lock); VN_RELE(vp); ncstats.dbl_enters++; ncs.ncs_dbl_enters.value.ui64++; TRACE_2(TR_FAC_NFS, TR_DNLC_ENTER_END, "dnlc_update_end:(%S) %d", "dbl enter", ncstats.dbl_enters); } VN_RELE(dp); dnlc_free(ncp); /* crfree done here */ return; } /* * insert the new entry, since it is not in dnlc yet */ nc_inshash(ncp, hp); mutex_exit(&hp->hash_lock); ncstats.enters++; ncs.ncs_enters.value.ui64++; TRACE_2(TR_FAC_NFS, TR_DNLC_ENTER_END, "dnlc_update_end:(%S) %d", "done", ncstats.enters); } /* * Look up a name in the directory name cache. * * Return a doubly-held vnode if found: one hold so that it may * remain in the cache for other users, the other hold so that * the cache is not re-cycled and the identity of the vnode is * lost before the caller can use the vnode. */ vnode_t * dnlc_lookup(vnode_t *dp, char *name) { ncache_t *ncp; nc_hash_t *hp; vnode_t *vp; int hash, depth; uchar_t namlen; TRACE_2(TR_FAC_NFS, TR_DNLC_LOOKUP_START, "dnlc_lookup_start:dp %x name %s", dp, name); if (!doingcache) { TRACE_4(TR_FAC_NFS, TR_DNLC_LOOKUP_END, "dnlc_lookup_end:%S %d vp %x name %s", "not_caching", 0, NULL, name); return (NULL); } DNLCHASH(name, dp, hash, namlen); depth = 1; hp = &nc_hash[hash & nc_hashmask]; mutex_enter(&hp->hash_lock); for (ncp = hp->hash_next; ncp != (ncache_t *)hp; ncp = ncp->hash_next) { if (ncp->hash == hash && /* fast signature check */ ncp->dp == dp && ncp->namlen == namlen && bcmp(ncp->name, name, namlen) == 0) { /* * Move this entry to the head of its hash chain * if it's not already close. */ if (depth > NC_MOVETOFRONT) { ncache_t *next = ncp->hash_next; ncache_t *prev = ncp->hash_prev; prev->hash_next = next; next->hash_prev = prev; ncp->hash_next = next = hp->hash_next; ncp->hash_prev = (ncache_t *)hp; next->hash_prev = ncp; hp->hash_next = ncp; ncstats.move_to_front++; } /* * Put a hold on the vnode now so its identity * can't change before the caller has a chance to * put a hold on it. */ vp = ncp->vp; VN_HOLD(vp); mutex_exit(&hp->hash_lock); ncstats.hits++; ncs.ncs_hits.value.ui64++; if (vp == DNLC_NO_VNODE) { ncs.ncs_neg_hits.value.ui64++; } TRACE_4(TR_FAC_NFS, TR_DNLC_LOOKUP_END, "dnlc_lookup_end:%S %d vp %x name %s", "hit", ncstats.hits, vp, name); return (vp); } depth++; } mutex_exit(&hp->hash_lock); ncstats.misses++; ncs.ncs_misses.value.ui64++; TRACE_4(TR_FAC_NFS, TR_DNLC_LOOKUP_END, "dnlc_lookup_end:%S %d vp %x name %s", "miss", ncstats.misses, NULL, name); return (NULL); } /* * Remove an entry in the directory name cache. */ void dnlc_remove(vnode_t *dp, char *name) { ncache_t *ncp; nc_hash_t *hp; uchar_t namlen; int hash; if (!doingcache) return; DNLCHASH(name, dp, hash, namlen); hp = &nc_hash[hash & nc_hashmask]; mutex_enter(&hp->hash_lock); if (ncp = dnlc_search(dp, name, namlen, hash)) { /* * Free up the entry */ nc_rmhash(ncp); mutex_exit(&hp->hash_lock); VN_RELE(ncp->vp); VN_RELE(ncp->dp); dnlc_free(ncp); return; } mutex_exit(&hp->hash_lock); } /* * Purge the entire cache. */ void dnlc_purge() { nc_hash_t *nch; ncache_t *ncp; int index; int i; vnode_t *nc_rele[DNLC_MAX_RELE]; if (!doingcache) return; ncstats.purges++; ncs.ncs_purge_all.value.ui64++; for (nch = nc_hash; nch < &nc_hash[nc_hashsz]; nch++) { index = 0; mutex_enter(&nch->hash_lock); ncp = nch->hash_next; while (ncp != (ncache_t *)nch) { ncache_t *np; np = ncp->hash_next; nc_rele[index++] = ncp->vp; nc_rele[index++] = ncp->dp; nc_rmhash(ncp); dnlc_free(ncp); ncp = np; ncs.ncs_purge_total.value.ui64++; if (index == DNLC_MAX_RELE) break; } mutex_exit(&nch->hash_lock); /* Release holds on all the vnodes now that we have no locks */ for (i = 0; i < index; i++) { VN_RELE(nc_rele[i]); } if (ncp != (ncache_t *)nch) { nch--; /* Do current hash chain again */ } } } /* * Purge any cache entries referencing a vnode. * Exit as soon as the vnode reference count goes to 1, as the caller * must hold a reference, and the dnlc can therefore have no more. */ void dnlc_purge_vp(vnode_t *vp) { nc_hash_t *nch; ncache_t *ncp; int index; vnode_t *nc_rele[DNLC_MAX_RELE]; ASSERT(vp->v_count > 0); if (vp->v_count == 1) { return; } if (!doingcache) return; ncstats.purges++; ncs.ncs_purge_vp.value.ui64++; for (nch = nc_hash; nch < &nc_hash[nc_hashsz]; nch++) { index = 0; mutex_enter(&nch->hash_lock); ncp = nch->hash_next; while (ncp != (ncache_t *)nch) { ncache_t *np; np = ncp->hash_next; if (ncp->dp == vp || ncp->vp == vp) { nc_rele[index++] = ncp->vp; nc_rele[index++] = ncp->dp; nc_rmhash(ncp); dnlc_free(ncp); ncs.ncs_purge_total.value.ui64++; if (index == DNLC_MAX_RELE) { ncp = np; break; } } ncp = np; } mutex_exit(&nch->hash_lock); /* Release holds on all the vnodes now that we have no locks */ while (index) { VN_RELE(nc_rele[--index]); } if (vp->v_count == 1) { return; /* no more dnlc references */ } if (ncp != (ncache_t *)nch) { nch--; /* Do current hash chain again */ } } } /* * Purge cache entries referencing a vfsp. Caller supplies a count * of entries to purge; up to that many will be freed. A count of * zero indicates that all such entries should be purged. Returns * the number of entries that were purged. */ int dnlc_purge_vfsp(vfs_t *vfsp, int count) { nc_hash_t *nch; ncache_t *ncp; int n = 0; int index; int i; vnode_t *nc_rele[DNLC_MAX_RELE]; if (!doingcache) return (0); ncstats.purges++; ncs.ncs_purge_vfs.value.ui64++; for (nch = nc_hash; nch < &nc_hash[nc_hashsz]; nch++) { index = 0; mutex_enter(&nch->hash_lock); ncp = nch->hash_next; while (ncp != (ncache_t *)nch) { ncache_t *np; np = ncp->hash_next; ASSERT(ncp->dp != NULL); ASSERT(ncp->vp != NULL); if ((ncp->dp->v_vfsp == vfsp) || (ncp->vp->v_vfsp == vfsp)) { n++; nc_rele[index++] = ncp->vp; nc_rele[index++] = ncp->dp; nc_rmhash(ncp); dnlc_free(ncp); ncs.ncs_purge_total.value.ui64++; if (index == DNLC_MAX_RELE) { ncp = np; break; } if (count != 0 && n >= count) { break; } } ncp = np; } mutex_exit(&nch->hash_lock); /* Release holds on all the vnodes now that we have no locks */ for (i = 0; i < index; i++) { VN_RELE(nc_rele[i]); } if (count != 0 && n >= count) { return (n); } if (ncp != (ncache_t *)nch) { nch--; /* Do current hash chain again */ } } return (n); } /* * Purge 1 entry from the dnlc that is part of the filesystem(s) * represented by 'vop'. The purpose of this routine is to allow * users of the dnlc to free a vnode that is being held by the dnlc. * * If we find a vnode that we release which will result in * freeing the underlying vnode (count was 1), return 1, 0 * if no appropriate vnodes found. * * Note, vop is not the 'right' identifier for a filesystem. */ int dnlc_fs_purge1(vnodeops_t *vop) { nc_hash_t *end; nc_hash_t *hp; ncache_t *ncp; vnode_t *vp; if (!doingcache) return (0); ncs.ncs_purge_fs1.value.ui64++; /* * Scan the dnlc entries looking for a likely candidate. */ hp = end = dnlc_purge_fs1_rotor; do { if (++hp == &nc_hash[nc_hashsz]) hp = nc_hash; dnlc_purge_fs1_rotor = hp; if (hp->hash_next == (ncache_t *)hp) continue; mutex_enter(&hp->hash_lock); for (ncp = hp->hash_prev; ncp != (ncache_t *)hp; ncp = ncp->hash_prev) { vp = ncp->vp; if (!vn_has_cached_data(vp) && (vp->v_count == 1) && vn_matchops(vp, vop)) break; } if (ncp != (ncache_t *)hp) { nc_rmhash(ncp); mutex_exit(&hp->hash_lock); VN_RELE(ncp->dp); VN_RELE(vp) dnlc_free(ncp); ncs.ncs_purge_total.value.ui64++; return (1); } mutex_exit(&hp->hash_lock); } while (hp != end); return (0); } /* * Perform a reverse lookup in the DNLC. This will find the first occurrence of * the vnode. If successful, it will return the vnode of the parent, and the * name of the entry in the given buffer. If it cannot be found, or the buffer * is too small, then it will return NULL. Note that this is a highly * inefficient function, since the DNLC is constructed solely for forward * lookups. */ vnode_t * dnlc_reverse_lookup(vnode_t *vp, char *buf, size_t buflen) { nc_hash_t *nch; ncache_t *ncp; vnode_t *pvp; if (!doingcache) return (NULL); for (nch = nc_hash; nch < &nc_hash[nc_hashsz]; nch++) { mutex_enter(&nch->hash_lock); ncp = nch->hash_next; while (ncp != (ncache_t *)nch) { /* * We ignore '..' entries since it can create * confusion and infinite loops. */ if (ncp->vp == vp && !(ncp->namlen == 2 && 0 == bcmp(ncp->name, "..", 2)) && ncp->namlen < buflen) { bcopy(ncp->name, buf, ncp->namlen); buf[ncp->namlen] = '\0'; pvp = ncp->dp; VN_HOLD(pvp); mutex_exit(&nch->hash_lock); return (pvp); } ncp = ncp->hash_next; } mutex_exit(&nch->hash_lock); } return (NULL); } /* * Utility routine to search for a cache entry. Return the * ncache entry if found, NULL otherwise. */ static ncache_t * dnlc_search(vnode_t *dp, char *name, uchar_t namlen, int hash) { nc_hash_t *hp; ncache_t *ncp; hp = &nc_hash[hash & nc_hashmask]; for (ncp = hp->hash_next; ncp != (ncache_t *)hp; ncp = ncp->hash_next) { if (ncp->hash == hash && ncp->dp == dp && ncp->namlen == namlen && bcmp(ncp->name, name, namlen) == 0) return (ncp); } return (NULL); } #if ((1 << NBBY) - 1) < (MAXNAMELEN - 1) #error ncache_t name length representation is too small #endif /* * Get a new name cache entry. * If the dnlc_reduce_cache() taskq isn't keeping up with demand, or memory * is short then just return NULL. If we're over ncsize then kick off a * thread to free some in use entries down to dnlc_nentries_low_water. * Caller must initialise all fields except namlen. * Component names are defined to be less than MAXNAMELEN * which includes a null. */ static ncache_t * dnlc_get(uchar_t namlen) { ncache_t *ncp; if (dnlc_nentries > dnlc_max_nentries) { dnlc_max_nentries_cnt++; /* keep a statistic */ return (NULL); } ncp = kmem_alloc(sizeof (ncache_t) + namlen, KM_NOSLEEP); if (ncp == NULL) { return (NULL); } ncp->namlen = namlen; atomic_add_32(&dnlc_nentries, 1); if (dnlc_reduce_idle && (dnlc_nentries >= ncsize)) { dnlc_reduce_idle = 0; (void) taskq_dispatch(system_taskq, dnlc_reduce_cache, NULL, TQ_SLEEP); } return (ncp); } /* * Taskq routine to free up name cache entries to reduce the * cache size to the low water mark. */ /*ARGSUSED*/ static void dnlc_reduce_cache(void *unused) { nc_hash_t *hp = dnlc_free_rotor; vnode_t *vp; ncache_t *ncp; int cnt; do { /* * Find the first non empty hash queue without locking * Recheck we really have entries to avoid * an infinite loop if all the entries get purged. */ do { if (++hp == &nc_hash[nc_hashsz]) { hp = nc_hash; if (dnlc_nentries < dnlc_nentries_low_water) { dnlc_reduce_idle = 1; return; } } } while (hp->hash_next == (ncache_t *)hp); mutex_enter(&hp->hash_lock); for (cnt = 0, ncp = hp->hash_prev; ncp != (ncache_t *)hp; ncp = ncp->hash_prev, cnt++) { vp = ncp->vp; /* * A name cache entry with a reference count * of one is only referenced by the dnlc. * Also negative cache entries are purged first. */ if (!vn_has_cached_data(vp) && ((vp->v_count == 1) || (vp == DNLC_NO_VNODE))) { ncs.ncs_pick_heur.value.ui64++; goto found; } /* * Remove from the end of the chain if the * chain is too long */ if (cnt > dnlc_long_chain) { ncp = hp->hash_prev; ncs.ncs_pick_last.value.ui64++; vp = ncp->vp; goto found; } } /* check for race and continue */ if (hp->hash_next == (ncache_t *)hp) { mutex_exit(&hp->hash_lock); continue; } ncp = hp->hash_prev; /* pick the last one in the hash queue */ ncs.ncs_pick_last.value.ui64++; vp = ncp->vp; found: /* * Remove from hash chain. */ nc_rmhash(ncp); mutex_exit(&hp->hash_lock); VN_RELE(vp); VN_RELE(ncp->dp); dnlc_free(ncp); } while (dnlc_nentries > dnlc_nentries_low_water); dnlc_free_rotor = hp; dnlc_reduce_idle = 1; } /* * Directory caching routines * ========================== * * See dnlc.h for details of the interfaces below. */ /* * Lookup up an entry in a complete or partial directory cache. */ dcret_t dnlc_dir_lookup(dcanchor_t *dcap, char *name, uint64_t *handle) { dircache_t *dcp; dcentry_t *dep; int hash; int ret; uchar_t namlen; /* * can test without lock as we are only a cache */ if (!VALID_DIR_CACHE(dcap->dca_dircache)) { ncs.ncs_dir_misses.value.ui64++; return (DNOCACHE); } if (!dnlc_dir_enable) { return (DNOCACHE); } mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (VALID_DIR_CACHE(dcp)) { dcp->dc_actime = lbolt64; DNLC_DIR_HASH(name, hash, namlen); dep = dcp->dc_namehash[hash & dcp->dc_nhash_mask]; while (dep != NULL) { if ((dep->de_hash == hash) && (namlen == dep->de_namelen) && bcmp(dep->de_name, name, namlen) == 0) { *handle = dep->de_handle; mutex_exit(&dcap->dca_lock); ncs.ncs_dir_hits.value.ui64++; return (DFOUND); } dep = dep->de_next; } if (dcp->dc_complete) { ret = DNOENT; } else { ret = DNOCACHE; } mutex_exit(&dcap->dca_lock); return (ret); } else { mutex_exit(&dcap->dca_lock); ncs.ncs_dir_misses.value.ui64++; return (DNOCACHE); } } /* * Start a new directory cache. An estimate of the number of * entries is provided to as a quick check to ensure the directory * is cacheable. */ dcret_t dnlc_dir_start(dcanchor_t *dcap, uint_t num_entries) { dircache_t *dcp; if (!dnlc_dir_enable || (num_entries < dnlc_dir_min_size)) { return (DNOCACHE); } if (num_entries > dnlc_dir_max_size) { return (DTOOBIG); } mutex_enter(&dc_head.dch_lock); mutex_enter(&dcap->dca_lock); if (dcap->dca_dircache == DC_RET_LOW_MEM) { dcap->dca_dircache = NULL; mutex_exit(&dcap->dca_lock); mutex_exit(&dc_head.dch_lock); return (DNOMEM); } /* * Check if there's currently a cache. * This probably only occurs on a race. */ if (dcap->dca_dircache != NULL) { mutex_exit(&dcap->dca_lock); mutex_exit(&dc_head.dch_lock); return (DNOCACHE); } /* * Allocate the dircache struct, entry and free space hash tables. * These tables are initially just one entry but dynamically resize * when entries and free space are added or removed. */ if ((dcp = kmem_zalloc(sizeof (dircache_t), KM_NOSLEEP)) == NULL) { goto error; } if ((dcp->dc_namehash = kmem_zalloc(sizeof (dcentry_t *), KM_NOSLEEP)) == NULL) { goto error; } if ((dcp->dc_freehash = kmem_zalloc(sizeof (dcfree_t *), KM_NOSLEEP)) == NULL) { goto error; } dcp->dc_anchor = dcap; /* set back pointer to anchor */ dcap->dca_dircache = dcp; /* add into head of global chain */ dcp->dc_next = dc_head.dch_next; dcp->dc_prev = (dircache_t *)&dc_head; dcp->dc_next->dc_prev = dcp; dc_head.dch_next = dcp; mutex_exit(&dcap->dca_lock); mutex_exit(&dc_head.dch_lock); ncs.ncs_cur_dirs.value.ui64++; ncs.ncs_dirs_cached.value.ui64++; return (DOK); error: if (dcp != NULL) { if (dcp->dc_namehash) { kmem_free(dcp->dc_namehash, sizeof (dcentry_t *)); } kmem_free(dcp, sizeof (dircache_t)); } /* * Must also kmem_free dcp->dc_freehash if more error cases are added */ mutex_exit(&dcap->dca_lock); mutex_exit(&dc_head.dch_lock); ncs.ncs_dir_start_nm.value.ui64++; return (DNOCACHE); } /* * Add a directopry entry to a partial or complete directory cache. */ dcret_t dnlc_dir_add_entry(dcanchor_t *dcap, char *name, uint64_t handle) { dircache_t *dcp; dcentry_t **hp, *dep; int hash; uint_t capacity; uchar_t namlen; /* * Allocate the dcentry struct, including the variable * size name. Note, the null terminator is not copied. * * We do this outside the lock to avoid possible deadlock if * dnlc_dir_reclaim() is called as a result of memory shortage. */ DNLC_DIR_HASH(name, hash, namlen); dep = kmem_alloc(sizeof (dcentry_t) - 1 + namlen, KM_NOSLEEP); if (dep == NULL) { #ifdef DEBUG /* * The kmem allocator generates random failures for * KM_NOSLEEP calls (see KMEM_RANDOM_ALLOCATION_FAILURE) * So try again before we blow away a perfectly good cache. * This is done not to cover an error but purely for * performance running a debug kernel. * This random error only occurs in debug mode. */ dep = kmem_alloc(sizeof (dcentry_t) - 1 + namlen, KM_NOSLEEP); if (dep != NULL) goto ok; #endif ncs.ncs_dir_add_nm.value.ui64++; /* * Free a directory cache. This may be the one we are * called with. */ dnlc_dir_reclaim(NULL); dep = kmem_alloc(sizeof (dcentry_t) - 1 + namlen, KM_NOSLEEP); if (dep == NULL) { /* * still no memory, better delete this cache */ mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (VALID_DIR_CACHE(dcp)) { dnlc_dir_abort(dcp); dcap->dca_dircache = DC_RET_LOW_MEM; } mutex_exit(&dcap->dca_lock); ncs.ncs_dir_addabort.value.ui64++; return (DNOCACHE); } /* * fall through as if the 1st kmem_alloc had worked */ } #ifdef DEBUG ok: #endif mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (VALID_DIR_CACHE(dcp)) { /* * If the total number of entries goes above the max * then free this cache */ if ((dcp->dc_num_entries + dcp->dc_num_free) > dnlc_dir_max_size) { mutex_exit(&dcap->dca_lock); dnlc_dir_purge(dcap); kmem_free(dep, sizeof (dcentry_t) - 1 + namlen); ncs.ncs_dir_add_max.value.ui64++; return (DTOOBIG); } dcp->dc_num_entries++; capacity = (dcp->dc_nhash_mask + 1) << dnlc_dir_hash_size_shift; if (dcp->dc_num_entries >= (capacity << dnlc_dir_hash_resize_shift)) { dnlc_dir_adjust_nhash(dcp); } hp = &dcp->dc_namehash[hash & dcp->dc_nhash_mask]; /* * Initialise and chain in new entry */ dep->de_handle = handle; dep->de_hash = hash; /* * Note de_namelen is a uchar_t to conserve space * and alignment padding. The max length of any * pathname component is defined as MAXNAMELEN * which is 256 (including the terminating null). * So provided this doesn't change, we don't include the null, * we always use bcmp to compare strings, and we don't * start storing full names, then we are ok. * The space savings is worth it. */ dep->de_namelen = namlen; bcopy(name, dep->de_name, namlen); dep->de_next = *hp; *hp = dep; dcp->dc_actime = lbolt64; mutex_exit(&dcap->dca_lock); ncs.ncs_dir_num_ents.value.ui64++; return (DOK); } else { mutex_exit(&dcap->dca_lock); kmem_free(dep, sizeof (dcentry_t) - 1 + namlen); return (DNOCACHE); } } /* * Add free space to a partial or complete directory cache. */ dcret_t dnlc_dir_add_space(dcanchor_t *dcap, uint_t len, uint64_t handle) { dircache_t *dcp; dcfree_t *dfp, **hp; uint_t capacity; /* * We kmem_alloc outside the lock to avoid possible deadlock if * dnlc_dir_reclaim() is called as a result of memory shortage. */ dfp = kmem_cache_alloc(dnlc_dir_space_cache, KM_NOSLEEP); if (dfp == NULL) { #ifdef DEBUG /* * The kmem allocator generates random failures for * KM_NOSLEEP calls (see KMEM_RANDOM_ALLOCATION_FAILURE) * So try again before we blow away a perfectly good cache. * This random error only occurs in debug mode */ dfp = kmem_cache_alloc(dnlc_dir_space_cache, KM_NOSLEEP); if (dfp != NULL) goto ok; #endif ncs.ncs_dir_add_nm.value.ui64++; /* * Free a directory cache. This may be the one we are * called with. */ dnlc_dir_reclaim(NULL); dfp = kmem_cache_alloc(dnlc_dir_space_cache, KM_NOSLEEP); if (dfp == NULL) { /* * still no memory, better delete this cache */ mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (VALID_DIR_CACHE(dcp)) { dnlc_dir_abort(dcp); dcap->dca_dircache = DC_RET_LOW_MEM; } mutex_exit(&dcap->dca_lock); ncs.ncs_dir_addabort.value.ui64++; return (DNOCACHE); } /* * fall through as if the 1st kmem_alloc had worked */ } #ifdef DEBUG ok: #endif mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (VALID_DIR_CACHE(dcp)) { if ((dcp->dc_num_entries + dcp->dc_num_free) > dnlc_dir_max_size) { mutex_exit(&dcap->dca_lock); dnlc_dir_purge(dcap); kmem_cache_free(dnlc_dir_space_cache, dfp); ncs.ncs_dir_add_max.value.ui64++; return (DTOOBIG); } dcp->dc_num_free++; capacity = (dcp->dc_fhash_mask + 1) << dnlc_dir_hash_size_shift; if (dcp->dc_num_free >= (capacity << dnlc_dir_hash_resize_shift)) { dnlc_dir_adjust_fhash(dcp); } /* * Initialise and chain a new entry */ dfp->df_handle = handle; dfp->df_len = len; dcp->dc_actime = lbolt64; hp = &(dcp->dc_freehash[DDFHASH(handle, dcp)]); dfp->df_next = *hp; *hp = dfp; mutex_exit(&dcap->dca_lock); ncs.ncs_dir_num_ents.value.ui64++; return (DOK); } else { mutex_exit(&dcap->dca_lock); kmem_cache_free(dnlc_dir_space_cache, dfp); return (DNOCACHE); } } /* * Mark a directory cache as complete. */ void dnlc_dir_complete(dcanchor_t *dcap) { dircache_t *dcp; mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (VALID_DIR_CACHE(dcp)) { dcp->dc_complete = B_TRUE; } mutex_exit(&dcap->dca_lock); } /* * Internal routine to delete a partial or full directory cache. * No additional locking needed. */ static void dnlc_dir_abort(dircache_t *dcp) { dcentry_t *dep, *nhp; dcfree_t *fep, *fhp; uint_t nhtsize = dcp->dc_nhash_mask + 1; /* name hash table size */ uint_t fhtsize = dcp->dc_fhash_mask + 1; /* free hash table size */ uint_t i; /* * Free up the cached name entries and hash table */ for (i = 0; i < nhtsize; i++) { /* for each hash bucket */ nhp = dcp->dc_namehash[i]; while (nhp != NULL) { /* for each chained entry */ dep = nhp->de_next; kmem_free(nhp, sizeof (dcentry_t) - 1 + nhp->de_namelen); nhp = dep; } } kmem_free(dcp->dc_namehash, sizeof (dcentry_t *) * nhtsize); /* * Free up the free space entries and hash table */ for (i = 0; i < fhtsize; i++) { /* for each hash bucket */ fhp = dcp->dc_freehash[i]; while (fhp != NULL) { /* for each chained entry */ fep = fhp->df_next; kmem_cache_free(dnlc_dir_space_cache, fhp); fhp = fep; } } kmem_free(dcp->dc_freehash, sizeof (dcfree_t *) * fhtsize); /* * Finally free the directory cache structure itself */ ncs.ncs_dir_num_ents.value.ui64 -= (dcp->dc_num_entries + dcp->dc_num_free); kmem_free(dcp, sizeof (dircache_t)); ncs.ncs_cur_dirs.value.ui64--; } /* * Remove a partial or complete directory cache */ void dnlc_dir_purge(dcanchor_t *dcap) { dircache_t *dcp; mutex_enter(&dc_head.dch_lock); mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (!VALID_DIR_CACHE(dcp)) { mutex_exit(&dcap->dca_lock); mutex_exit(&dc_head.dch_lock); return; } dcap->dca_dircache = NULL; /* * Unchain from global list */ dcp->dc_prev->dc_next = dcp->dc_next; dcp->dc_next->dc_prev = dcp->dc_prev; mutex_exit(&dcap->dca_lock); mutex_exit(&dc_head.dch_lock); dnlc_dir_abort(dcp); } /* * Remove an entry from a complete or partial directory cache. * Return the handle if it's non null. */ dcret_t dnlc_dir_rem_entry(dcanchor_t *dcap, char *name, uint64_t *handlep) { dircache_t *dcp; dcentry_t **prevpp, *te; uint_t capacity; int hash; int ret; uchar_t namlen; if (!dnlc_dir_enable) { return (DNOCACHE); } mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (VALID_DIR_CACHE(dcp)) { dcp->dc_actime = lbolt64; if (dcp->dc_nhash_mask > 0) { /* ie not minimum */ capacity = (dcp->dc_nhash_mask + 1) << dnlc_dir_hash_size_shift; if (dcp->dc_num_entries <= (capacity >> dnlc_dir_hash_resize_shift)) { dnlc_dir_adjust_nhash(dcp); } } DNLC_DIR_HASH(name, hash, namlen); prevpp = &dcp->dc_namehash[hash & dcp->dc_nhash_mask]; while (*prevpp != NULL) { if (((*prevpp)->de_hash == hash) && (namlen == (*prevpp)->de_namelen) && bcmp((*prevpp)->de_name, name, namlen) == 0) { if (handlep != NULL) { *handlep = (*prevpp)->de_handle; } te = *prevpp; *prevpp = (*prevpp)->de_next; kmem_free(te, sizeof (dcentry_t) - 1 + te->de_namelen); /* * If the total number of entries * falls below half the minimum number * of entries then free this cache. */ if (--dcp->dc_num_entries < (dnlc_dir_min_size >> 1)) { mutex_exit(&dcap->dca_lock); dnlc_dir_purge(dcap); } else { mutex_exit(&dcap->dca_lock); } ncs.ncs_dir_num_ents.value.ui64--; return (DFOUND); } prevpp = &((*prevpp)->de_next); } if (dcp->dc_complete) { ncs.ncs_dir_reme_fai.value.ui64++; ret = DNOENT; } else { ret = DNOCACHE; } mutex_exit(&dcap->dca_lock); return (ret); } else { mutex_exit(&dcap->dca_lock); return (DNOCACHE); } } /* * Remove free space of at least the given length from a complete * or partial directory cache. */ dcret_t dnlc_dir_rem_space_by_len(dcanchor_t *dcap, uint_t len, uint64_t *handlep) { dircache_t *dcp; dcfree_t **prevpp, *tfp; uint_t fhtsize; /* free hash table size */ uint_t i; uint_t capacity; int ret; if (!dnlc_dir_enable) { return (DNOCACHE); } mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (VALID_DIR_CACHE(dcp)) { dcp->dc_actime = lbolt64; if (dcp->dc_fhash_mask > 0) { /* ie not minimum */ capacity = (dcp->dc_fhash_mask + 1) << dnlc_dir_hash_size_shift; if (dcp->dc_num_free <= (capacity >> dnlc_dir_hash_resize_shift)) { dnlc_dir_adjust_fhash(dcp); } } /* * Search for an entry of the appropriate size * on a first fit basis. */ fhtsize = dcp->dc_fhash_mask + 1; for (i = 0; i < fhtsize; i++) { /* for each hash bucket */ prevpp = &(dcp->dc_freehash[i]); while (*prevpp != NULL) { if ((*prevpp)->df_len >= len) { *handlep = (*prevpp)->df_handle; tfp = *prevpp; *prevpp = (*prevpp)->df_next; dcp->dc_num_free--; mutex_exit(&dcap->dca_lock); kmem_cache_free(dnlc_dir_space_cache, tfp); ncs.ncs_dir_num_ents.value.ui64--; return (DFOUND); } prevpp = &((*prevpp)->df_next); } } if (dcp->dc_complete) { ret = DNOENT; } else { ret = DNOCACHE; } mutex_exit(&dcap->dca_lock); return (ret); } else { mutex_exit(&dcap->dca_lock); return (DNOCACHE); } } /* * Remove free space with the given handle from a complete or partial * directory cache. */ dcret_t dnlc_dir_rem_space_by_handle(dcanchor_t *dcap, uint64_t handle) { dircache_t *dcp; dcfree_t **prevpp, *tfp; uint_t capacity; int ret; if (!dnlc_dir_enable) { return (DNOCACHE); } mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (VALID_DIR_CACHE(dcp)) { dcp->dc_actime = lbolt64; if (dcp->dc_fhash_mask > 0) { /* ie not minimum */ capacity = (dcp->dc_fhash_mask + 1) << dnlc_dir_hash_size_shift; if (dcp->dc_num_free <= (capacity >> dnlc_dir_hash_resize_shift)) { dnlc_dir_adjust_fhash(dcp); } } /* * search for the exact entry */ prevpp = &(dcp->dc_freehash[DDFHASH(handle, dcp)]); while (*prevpp != NULL) { if ((*prevpp)->df_handle == handle) { tfp = *prevpp; *prevpp = (*prevpp)->df_next; dcp->dc_num_free--; mutex_exit(&dcap->dca_lock); kmem_cache_free(dnlc_dir_space_cache, tfp); ncs.ncs_dir_num_ents.value.ui64--; return (DFOUND); } prevpp = &((*prevpp)->df_next); } if (dcp->dc_complete) { ncs.ncs_dir_rems_fai.value.ui64++; ret = DNOENT; } else { ret = DNOCACHE; } mutex_exit(&dcap->dca_lock); return (ret); } else { mutex_exit(&dcap->dca_lock); return (DNOCACHE); } } /* * Update the handle of an directory cache entry. */ dcret_t dnlc_dir_update(dcanchor_t *dcap, char *name, uint64_t handle) { dircache_t *dcp; dcentry_t *dep; int hash; int ret; uchar_t namlen; if (!dnlc_dir_enable) { return (DNOCACHE); } mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (VALID_DIR_CACHE(dcp)) { dcp->dc_actime = lbolt64; DNLC_DIR_HASH(name, hash, namlen); dep = dcp->dc_namehash[hash & dcp->dc_nhash_mask]; while (dep != NULL) { if ((dep->de_hash == hash) && (namlen == dep->de_namelen) && bcmp(dep->de_name, name, namlen) == 0) { dep->de_handle = handle; mutex_exit(&dcap->dca_lock); return (DFOUND); } dep = dep->de_next; } if (dcp->dc_complete) { ncs.ncs_dir_upd_fail.value.ui64++; ret = DNOENT; } else { ret = DNOCACHE; } mutex_exit(&dcap->dca_lock); return (ret); } else { mutex_exit(&dcap->dca_lock); return (DNOCACHE); } } void dnlc_dir_fini(dcanchor_t *dcap) { dircache_t *dcp; mutex_enter(&dc_head.dch_lock); mutex_enter(&dcap->dca_lock); dcp = (dircache_t *)dcap->dca_dircache; if (VALID_DIR_CACHE(dcp)) { /* * Unchain from global list */ ncs.ncs_dir_finipurg.value.ui64++; dcp->dc_prev->dc_next = dcp->dc_next; dcp->dc_next->dc_prev = dcp->dc_prev; } else { dcp = NULL; } dcap->dca_dircache = NULL; mutex_exit(&dcap->dca_lock); mutex_exit(&dc_head.dch_lock); mutex_destroy(&dcap->dca_lock); if (dcp) { dnlc_dir_abort(dcp); } } /* * Reclaim callback for dnlc directory caching. * Invoked by the kernel memory allocator when memory gets tight. * This is a pretty serious condition and can lead easily lead to system * hangs if not enough space is returned. * * Deciding which directory (or directories) to purge is tricky. * Purging everything is an overkill, but purging just the oldest used * was found to lead to hangs. The largest cached directories use the * most memory, but take the most effort to rebuild, whereas the smaller * ones have little value and give back little space. So what to do? * * The current policy is to continue purging the oldest used directories * until at least dnlc_dir_min_reclaim directory entries have been purged. */ /*ARGSUSED*/ static void dnlc_dir_reclaim(void *unused) { dircache_t *dcp, *oldest; uint_t dirent_cnt = 0; mutex_enter(&dc_head.dch_lock); while (dirent_cnt < dnlc_dir_min_reclaim) { dcp = dc_head.dch_next; oldest = NULL; while (dcp != (dircache_t *)&dc_head) { if (oldest == NULL) { oldest = dcp; } else { if (dcp->dc_actime < oldest->dc_actime) { oldest = dcp; } } dcp = dcp->dc_next; } if (oldest == NULL) { /* nothing to delete */ mutex_exit(&dc_head.dch_lock); return; } /* * remove from directory chain and purge */ oldest->dc_prev->dc_next = oldest->dc_next; oldest->dc_next->dc_prev = oldest->dc_prev; mutex_enter(&oldest->dc_anchor->dca_lock); /* * If this was the last entry then it must be too large. * Mark it as such by saving a special dircache_t * pointer (DC_RET_LOW_MEM) in the anchor. The error DNOMEM * will be presented to the caller of dnlc_dir_start() */ if (oldest->dc_next == oldest->dc_prev) { oldest->dc_anchor->dca_dircache = DC_RET_LOW_MEM; ncs.ncs_dir_rec_last.value.ui64++; } else { oldest->dc_anchor->dca_dircache = NULL; ncs.ncs_dir_recl_any.value.ui64++; } mutex_exit(&oldest->dc_anchor->dca_lock); dirent_cnt += oldest->dc_num_entries; dnlc_dir_abort(oldest); } mutex_exit(&dc_head.dch_lock); } /* * Dynamically grow or shrink the size of the name hash table */ static void dnlc_dir_adjust_nhash(dircache_t *dcp) { dcentry_t **newhash, *dep, **nhp, *tep; uint_t newsize; uint_t oldsize; uint_t newsizemask; int i; /* * Allocate new hash table */ newsize = dcp->dc_num_entries >> dnlc_dir_hash_size_shift; newhash = kmem_zalloc(sizeof (dcentry_t *) * newsize, KM_NOSLEEP); if (newhash == NULL) { /* * System is short on memory just return * Note, the old hash table is still usable. * This return is unlikely to repeatedy occur, because * either some other directory caches will be reclaimed * due to memory shortage, thus freeing memory, or this * directory cahe will be reclaimed. */ return; } oldsize = dcp->dc_nhash_mask + 1; dcp->dc_nhash_mask = newsizemask = newsize - 1; /* * Move entries from the old table to the new */ for (i = 0; i < oldsize; i++) { /* for each hash bucket */ dep = dcp->dc_namehash[i]; while (dep != NULL) { /* for each chained entry */ tep = dep; dep = dep->de_next; nhp = &newhash[tep->de_hash & newsizemask]; tep->de_next = *nhp; *nhp = tep; } } /* * delete old hash table and set new one in place */ kmem_free(dcp->dc_namehash, sizeof (dcentry_t *) * oldsize); dcp->dc_namehash = newhash; } /* * Dynamically grow or shrink the size of the free space hash table */ static void dnlc_dir_adjust_fhash(dircache_t *dcp) { dcfree_t **newhash, *dfp, **nhp, *tfp; uint_t newsize; uint_t oldsize; int i; /* * Allocate new hash table */ newsize = dcp->dc_num_free >> dnlc_dir_hash_size_shift; newhash = kmem_zalloc(sizeof (dcfree_t *) * newsize, KM_NOSLEEP); if (newhash == NULL) { /* * System is short on memory just return * Note, the old hash table is still usable. * This return is unlikely to repeatedy occur, because * either some other directory caches will be reclaimed * due to memory shortage, thus freeing memory, or this * directory cahe will be reclaimed. */ return; } oldsize = dcp->dc_fhash_mask + 1; dcp->dc_fhash_mask = newsize - 1; /* * Move entries from the old table to the new */ for (i = 0; i < oldsize; i++) { /* for each hash bucket */ dfp = dcp->dc_freehash[i]; while (dfp != NULL) { /* for each chained entry */ tfp = dfp; dfp = dfp->df_next; nhp = &newhash[DDFHASH(tfp->df_handle, dcp)]; tfp->df_next = *nhp; *nhp = tfp; } } /* * delete old hash table and set new one in place */ kmem_free(dcp->dc_freehash, sizeof (dcfree_t *) * oldsize); dcp->dc_freehash = newhash; }