X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/43866e378188c25dd1e2208016ab3cbeb086ae6c..55e303ae13a4cf49d70f2294092726f2fffb9ef2:/bsd/vfs/vfs_cache.c diff --git a/bsd/vfs/vfs_cache.c b/bsd/vfs/vfs_cache.c index e4b72f554..cc59be0c6 100644 --- a/bsd/vfs/vfs_cache.c +++ b/bsd/vfs/vfs_cache.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. + * Copyright (c) 2000-2003 Apple Computer, Inc. All rights reserved. * * @APPLE_LICENSE_HEADER_START@ * @@ -94,8 +94,8 @@ /* * Structures associated with name cacheing. */ -#define NCHHASH(dvp, cnp) \ - (&nchashtbl[((dvp)->v_id + (cnp)->cn_hash) & nchash]) +#define NCHHASH(dvp, hash_val) \ + (&nchashtbl[((u_long)(dvp) ^ ((dvp)->v_id ^ (hash_val))) & nchash]) LIST_HEAD(nchashhead, namecache) *nchashtbl; /* Hash Table */ u_long nchash; /* size of hash table - 1 */ long numcache; /* number of cache entries allocated */ @@ -107,6 +107,10 @@ int doingcache = 1; /* 1 => enable the cache */ /* * Delete an entry from its hash list and move it to the front * of the LRU list for immediate reuse. + * + * NOTE: THESE MACROS CAN BLOCK (in the call to remove_name()) + * SO BE CAREFUL IF YOU HOLD POINTERS TO nclruhead OR + * nchashtbl. */ #if DIAGNOSTIC #define PURGE(ncp) { \ @@ -118,6 +122,9 @@ int doingcache = 1; /* 1 => enable the cache */ ncp->nc_hash.le_prev = 0; \ TAILQ_REMOVE(&nclruhead, ncp, nc_lru); \ TAILQ_INSERT_HEAD(&nclruhead, ncp, nc_lru); \ + /* this has to come last because it could block */ \ + remove_name(ncp->nc_name); \ + ncp->nc_name = NULL; \ } #else #define PURGE(ncp) { \ @@ -125,6 +132,9 @@ int doingcache = 1; /* 1 => enable the cache */ ncp->nc_hash.le_prev = 0; \ TAILQ_REMOVE(&nclruhead, ncp, nc_lru); \ TAILQ_INSERT_HEAD(&nclruhead, ncp, nc_lru); \ + /* this has to come last because it could block */ \ + remove_name(ncp->nc_name); \ + ncp->nc_name = NULL; \ } #endif /* DIAGNOSTIC */ @@ -139,6 +149,32 @@ int doingcache = 1; /* 1 => enable the cache */ } \ } + +// +// Have to take a len argument because we may only need to +// hash part of a componentname. +// +static unsigned int +hash_string(const char *str, int len) +{ + unsigned int i, hashval = 0; + + if (len == 0) { + for(i=1; *str != 0; i++, str++) { + hashval += (unsigned char)*str * i; + } + } else { + for(i=len; i > 0; i--, str++) { + hashval += (unsigned char)*str * (len - i + 1); + } + } + + return hashval; +} + + + + /* * Lookup an entry in the cache * @@ -162,32 +198,30 @@ cache_lookup(dvp, vpp, cnp) { register struct namecache *ncp, *nnp; register struct nchashhead *ncpp; + register long namelen = cnp->cn_namelen; + char *nameptr = cnp->cn_nameptr; if (!doingcache) { cnp->cn_flags &= ~MAKEENTRY; return (0); } - if (cnp->cn_namelen > NCHNAMLEN) { - nchstats.ncs_long++; - cnp->cn_flags &= ~MAKEENTRY; - return (0); - } - ncpp = NCHHASH(dvp, cnp); + ncpp = NCHHASH(dvp, cnp->cn_hash); for (ncp = ncpp->lh_first; ncp != 0; ncp = nnp) { nnp = ncp->nc_hash.le_next; - /* If one of the vp's went stale, don't bother anymore. */ - if ((ncp->nc_dvpid != ncp->nc_dvp->v_id) || - (ncp->nc_vp && ncp->nc_vpid != ncp->nc_vp->v_id)) { - nchstats.ncs_falsehits++; - PURGE(ncp); - continue; - } - /* Now that we know the vp's to be valid, is it ours ? */ + if (ncp->nc_dvp == dvp && - ncp->nc_nlen == cnp->cn_namelen && - !bcmp(ncp->nc_name, cnp->cn_nameptr, (u_int)ncp->nc_nlen)) + strncmp(ncp->nc_name, nameptr, namelen) == 0 && + ncp->nc_name[namelen] == 0) { + /* Make sure the vp isn't stale. */ + if ((ncp->nc_dvpid != dvp->v_id) || + (ncp->nc_vp && ncp->nc_vpid != ncp->nc_vp->v_id)) { + nchstats.ncs_falsehits++; + PURGE(ncp); + continue; + } break; + } } /* We failed to find an entry */ @@ -205,6 +239,11 @@ cache_lookup(dvp, vpp, cnp) /* We found a "positive" match, return the vnode */ if (ncp->nc_vp) { + if (ncp->nc_vp->v_flag & (VUINIT|VXLOCK|VTERMINATE|VORECLAIM)) { + PURGE(ncp); + return (0); + } + nchstats.ncs_goodhits++; TOUCH(ncp); *vpp = ncp->nc_vp; @@ -243,15 +282,6 @@ cache_enter(dvp, vp, cnp) if (!doingcache) return; - /* - * If an entry that is too long, is entered, bad things happen. - * cache_lookup acts as the sentinel to make sure longer names - * are not stored. This here will prevent outsiders from doing - * something that is unexpected. - */ - if (cnp->cn_namelen > NCHNAMLEN) - panic("cache_enter: name too long"); - /* * We allocate a new entry if we are less than the maximum * allowed and the one at the front of the LRU list is in use. @@ -273,6 +303,8 @@ cache_enter(dvp, vp, cnp) panic("cache_enter: le_next"); #endif LIST_REMOVE(ncp, nc_hash); + remove_name(ncp->nc_name); + ncp->nc_name = NULL; ncp->nc_hash.le_prev = 0; } } else { @@ -293,10 +325,9 @@ cache_enter(dvp, vp, cnp) ncp->nc_vpid = cnp->cn_flags & ISWHITEOUT; ncp->nc_dvp = dvp; ncp->nc_dvpid = dvp->v_id; - ncp->nc_nlen = cnp->cn_namelen; - bcopy(cnp->cn_nameptr, ncp->nc_name, (unsigned)ncp->nc_nlen); + ncp->nc_name = add_name(cnp->cn_nameptr, cnp->cn_namelen, cnp->cn_hash, 0); TAILQ_INSERT_TAIL(&nclruhead, ncp, nc_lru); - ncpp = NCHHASH(dvp, cnp); + ncpp = NCHHASH(dvp, cnp->cn_hash); #if DIAGNOSTIC { register struct namecache *p; @@ -315,11 +346,66 @@ cache_enter(dvp, vp, cnp) void nchinit() { + static void init_string_table(void); + + TAILQ_INIT(&nclruhead); + nchashtbl = hashinit(MAX(4096, desiredvnodes), M_CACHE, &nchash); - TAILQ_INIT(&nclruhead); - nchashtbl = hashinit(desiredvnodes, M_CACHE, &nchash); + init_string_table(); } + +int +resize_namecache(u_int newsize) +{ + struct nchashhead *new_table; + struct nchashhead *old_table; + struct nchashhead *old_head, *head; + struct namecache *entry, *next; + uint32_t i; + u_long new_mask, old_mask; + + // we don't support shrinking yet + if (newsize < nchash) { + return 0; + } + + new_table = hashinit(newsize, M_CACHE, &new_mask); + if (new_table == NULL) { + return ENOMEM; + } + + // do the switch! + old_table = nchashtbl; + nchashtbl = new_table; + old_mask = nchash; + nchash = new_mask; + + // walk the old table and insert all the entries into + // the new table + // + for(i=0; i <= old_mask; i++) { + old_head = &old_table[i]; + for (entry=old_head->lh_first; entry != NULL; entry=next) { + // + // XXXdbg - Beware: this assumes that hash_string() does + // the same thing as what happens in + // lookup() over in vfs_lookup.c + head = NCHHASH(entry->nc_dvp, hash_string(entry->nc_name, 0)); + + next = entry->nc_hash.le_next; + LIST_INSERT_HEAD(head, entry, nc_hash); + } + } + + FREE(old_table, M_CACHE); + + return 0; +} + + + + /* * Invalidate a all entries to particular vnode. * @@ -370,3 +456,187 @@ cache_purgevfs(mp) } } } + + + +// +// String ref routines +// +static LIST_HEAD(stringhead, string_t) *string_ref_table; +static u_long string_table_mask; +static uint32_t max_chain_len=0; +static struct stringhead *long_chain_head=NULL; +static uint32_t filled_buckets=0; +static uint32_t num_dups=0; +static uint32_t nstrings=0; + +typedef struct string_t { + LIST_ENTRY(string_t) hash_chain; + unsigned char *str; + uint32_t refcount; +} string_t; + + + +static int +resize_string_ref_table() +{ + struct stringhead *new_table; + struct stringhead *old_table; + struct stringhead *old_head, *head; + string_t *entry, *next; + uint32_t i, hashval; + u_long new_mask, old_mask; + + new_table = hashinit((string_table_mask + 1) * 2, M_CACHE, &new_mask); + if (new_table == NULL) { + return ENOMEM; + } + + // do the switch! + old_table = string_ref_table; + string_ref_table = new_table; + old_mask = string_table_mask; + string_table_mask = new_mask; + + printf("resize: max chain len %d, new table size %d\n", + max_chain_len, new_mask + 1); + max_chain_len = 0; + long_chain_head = NULL; + filled_buckets = 0; + + // walk the old table and insert all the entries into + // the new table + // + for(i=0; i <= old_mask; i++) { + old_head = &old_table[i]; + for (entry=old_head->lh_first; entry != NULL; entry=next) { + hashval = hash_string(entry->str, 0); + head = &string_ref_table[hashval & string_table_mask]; + if (head->lh_first == NULL) { + filled_buckets++; + } + + next = entry->hash_chain.le_next; + LIST_INSERT_HEAD(head, entry, hash_chain); + } + } + + FREE(old_table, M_CACHE); + + return 0; +} + + +static void +init_string_table(void) +{ + string_ref_table = hashinit(4096, M_CACHE, &string_table_mask); +} + + +char * +add_name(const char *name, size_t len, u_int hashval, u_int flags) +{ + struct stringhead *head; + string_t *entry; + int chain_len = 0; + + // + // If the table gets more than 3/4 full, resize it + // + if (4*filled_buckets >= ((string_table_mask + 1) * 3)) { + if (resize_string_ref_table() != 0) { + printf("failed to resize the hash table.\n"); + } + } + + if (hashval == 0) { + hashval = hash_string(name, len); + } + + head = &string_ref_table[hashval & string_table_mask]; + for (entry=head->lh_first; entry != NULL; chain_len++, entry=entry->hash_chain.le_next) { + if (strncmp(entry->str, name, len) == 0 && entry->str[len] == '\0') { + entry->refcount++; + num_dups++; + break; + } + } + + if (entry == NULL) { + // it wasn't already there so add it. + MALLOC(entry, string_t *, sizeof(string_t) + len + 1, M_TEMP, M_WAITOK); + + // have to get "head" again because we could have blocked + // in malloc and thus head could have changed. + // + head = &string_ref_table[hashval & string_table_mask]; + if (head->lh_first == NULL) { + filled_buckets++; + } + + LIST_INSERT_HEAD(head, entry, hash_chain); + entry->str = (char *)((char *)entry + sizeof(string_t)); + strncpy(entry->str, name, len); + entry->str[len] = '\0'; + entry->refcount = 1; + + if (chain_len > max_chain_len) { + max_chain_len = chain_len; + long_chain_head = head; + } + + nstrings++; + } + + return entry->str; +} + +int +remove_name(const char *nameref) +{ + struct stringhead *head; + string_t *entry; + uint32_t hashval; + + hashval = hash_string(nameref, 0); + head = &string_ref_table[hashval & string_table_mask]; + for (entry=head->lh_first; entry != NULL; entry=entry->hash_chain.le_next) { + if (entry->str == (unsigned char *)nameref) { + entry->refcount--; + if (entry->refcount == 0) { + LIST_REMOVE(entry, hash_chain); + if (head->lh_first == NULL) { + filled_buckets--; + } + entry->str = NULL; + nstrings--; + + FREE(entry, M_TEMP); + } else { + num_dups--; + } + + return 0; + } + } + + return ENOENT; +} + + +void +dump_string_table(void) +{ + struct stringhead *head; + string_t *entry; + int i; + + for(i=0; i <= string_table_mask; i++) { + head = &string_ref_table[i]; + for (entry=head->lh_first; entry != NULL; entry=entry->hash_chain.le_next) { + printf("%6d - %s\n", entry->refcount, entry->str); + } + } +}