/*
- * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 2000-2003 Apple Computer, Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
/*
* 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 */
/*
* 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) { \
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) { \
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 */
} \
}
+
+//
+// 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
*
{
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 */
/* 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;
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.
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 {
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;
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.
*
}
}
}
+
+
+
+//
+// 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);
+ }
+ }
+}
projects / apple / xnu.git / blobdiff