diff options
Diffstat (limited to 'libdiskfs')
| -rw-r--r-- | libdiskfs/name-cache.c | 108 |
1 files changed, 15 insertions, 93 deletions
diff --git a/libdiskfs/name-cache.c b/libdiskfs/name-cache.c index a4270fe9..2cf1ed8b 100644 --- a/libdiskfs/name-cache.c +++ b/libdiskfs/name-cache.c @@ -19,9 +19,9 @@ along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */ - #include "priv.h" #include <string.h> +#include <cacheq.h> /* Maximum number of names to cache at once */ #define MAXCACHE 256 @@ -32,6 +32,8 @@ /* Cache entry */ struct lookup_cache { + struct cacheq_hdr hdr; + /* Used to indentify nodes to the fs dependent code. 0 for NODE_CACHE_ID means a `negative' entry -- recording that there's definitely no node with this name. */ @@ -43,20 +45,10 @@ struct lookup_cache /* Strlen of NAME. If this is zero, it's an unused entry. */ size_t name_len; - - /* Next and prev entries in the cache, linked in LRU order. */ - struct lookup_cache *next, *prev; }; /* The contents of the cache in no particular order */ -static struct lookup_cache lookup_cache[MAXCACHE]; - -/* The least, and most, recently used entries in the cache. These point to - either end of a linked list composed of all the elements of LOOKUP_CACHE. - This list will always be the same length -- if an element is `removed', - its entry is simply marked inactive, and moved to the LRU end of the list - so it will be reused first. */ -static struct lookup_cache *lru_cache = 0, *mru_cache = 0; +static struct cacheq lookup_cache = { sizeof (struct lookup_cache) }; static spin_lock_t cache_lock = SPIN_LOCK_INITIALIZER; @@ -69,52 +61,6 @@ static struct long fetch_errors; } statistics; -/* Move C to the most-recently-used end of the cache. CACHE_LOCK must be - held. */ -static void -make_mru (struct lookup_cache *c) -{ - if (c != mru_cache) - { - /* First remove it. We known C->prev isn't 0 because C wasn't - previously == MRU_CACHE. */ - c->prev->next = c->next; - if (c->next) - c->next->prev = c->prev; - else - lru_cache = c->prev; - - /* Now make it MRU_CACHE. */ - c->next = mru_cache; - c->prev = 0; - mru_cache->prev = c; - mru_cache = c; - } -} - -/* Move C to the least-recently-used end of the cache. CACHE_LOCK must be - held. */ -static void -make_lru (struct lookup_cache *c) -{ - if (c != lru_cache) - { - /* First remove it. We known C->next isn't 0 because C wasn't - previously == LRU_CACHE. */ - c->next->prev = c->prev; - if (c->prev) - c->prev->next = c->next; - else - mru_cache = c->next; - - /* Now make it LRU_CACHE. */ - c->prev = lru_cache; - c->next = 0; - lru_cache->next = c; - lru_cache = c; - } -} - /* If there's an entry for NAME, of length NAME_LEN, in directory DIR in the cache, return it's entry, otherwise 0. CACHE_LOCK must be held. */ static struct lookup_cache * @@ -124,7 +70,7 @@ find_cache (struct node *dir, const char *name, size_t name_len) /* Search the list. All unused entries are contiguous at the end of the list, so we can stop searching when we see the first one. */ - for (c = mru_cache; c && c->name_len; c = c->next) + for (c = lookup_cache.mru; c && c->name_len; c = c->hdr.next) if (c->name_len == name_len && c->dir_cache_id == dir->cache_id && c->name[0] == name[0] && strcmp (c->name, name) == 0) @@ -133,31 +79,6 @@ find_cache (struct node *dir, const char *name, size_t name_len) return 0; } -/* Put all the elements of the LOOKUP_CACHE array in a doubly linked list - pointed to at either end by LRU_CACHE and MRU_CACHE, and initialize each - entry. */ -static void -init_lookup_cache () -{ - int i; - - lru_cache = mru_cache = &lookup_cache[0]; - - lru_cache->name_len = 0; - lru_cache->next = 0; - - for (i = 1; i < MAXCACHE; i++) - { - struct lookup_cache *c = &lookup_cache[i]; - c->name_len = 0; - c->next = mru_cache; - mru_cache->prev = c; - mru_cache = c; - } - - mru_cache->prev = 0; -} - /* Node NP has just been found in DIR with NAME. If NP is null, that means that this name has been confirmed as absent in the directory. */ void @@ -178,14 +99,14 @@ diskfs_enter_lookup_cache (struct node *dir, struct node *np, char *name) spin_lock (&cache_lock); - if (lru_cache == 0) + if (lookup_cache.length == 0) /* There should always be an lru_cache; this being zero means that the cache hasn't been initialized yet. Do so. */ - init_lookup_cache (); + cacheq_set_length (&lookup_cache, MAXCACHE); /* See if there's an old entry for NAME in DIR. If not, replace the least recently used entry. */ - c = find_cache (dir, name, name_len) ?: lru_cache; + c = find_cache (dir, name, name_len) ?: lookup_cache.lru; /* Fill C with the new entry. */ c->dir_cache_id = dir->cache_id; @@ -194,7 +115,7 @@ diskfs_enter_lookup_cache (struct node *dir, struct node *np, char *name) c->name_len = name_len; /* Now C becomes the MRU entry! */ - make_mru (c); + cacheq_make_mru (&lookup_cache, c); spin_unlock (&cache_lock); } @@ -207,17 +128,18 @@ diskfs_purge_lookup_cache (struct node *dp, struct node *np) struct lookup_cache *c, *next; spin_lock (&cache_lock); - for (c = mru_cache; c; c = next) + for (c = lookup_cache.mru; c; c = next) { - /* Save C->next, since we may delete C from this position in the list. */ - next = c->next; + /* Save C->hdr.next, since we may move C from this position. */ + next = c->hdr.next; if (c->name_len && c->dir_cache_id == dp->cache_id && c->node_cache_id == np->cache_id) { c->name_len = 0; - make_lru (c); /* Use C as the next free entry. */ + cacheq_make_lru (&lookup_cache, c); /* Use C as the next free + entry. */ } } spin_unlock (&cache_lock); @@ -239,7 +161,7 @@ diskfs_check_lookup_cache (struct node *dir, char *name) { int id = c->node_cache_id; - make_mru (c); /* Record C as recently used. */ + cacheq_make_mru (&lookup_cache, c); /* Record C as recently used. */ statistics.pos_hits++; spin_unlock (&cache_lock); |