autofs-5.0.8 - dont clobber mapent for negative cache

From: Ian Kent <raven@themaw.net>

When negative caching a map entry on mount fail don't save the mapent

and restore it when the negative cache timeout expires.

Deleting the mapent, as is done now, can be expensive especially when

it causes a file read for a large file map.

---

 daemon/lookup.c          |    6 ++-

 include/automount.h      |    9 ++++

 lib/cache.c              |   85 ++++++++++++++++++++++++++++++++++++++++++++++-

 modules/lookup_file.c    |    6 ++-

 modules/lookup_hosts.c   |   10 +++--

 modules/lookup_ldap.c    |    6 ++-

 modules/lookup_nisplus.c |   10 +++--

 modules/lookup_program.c |   10 +++--

 modules/lookup_sss.c     |    6 ++-

 modules/lookup_yp.c      |    6 ++-

 10 files changed, 135 insertions(+), 19 deletions(-)

--- autofs-5.0.7.orig/daemon/lookup.c

+++ autofs-5.0.7/daemon/lookup.c

@@ -860,7 +860,11 @@ static void update_negative_cache(struct

 			int rv = CHE_FAIL;

 			cache_writelock(map->mc);

-			rv = cache_update(map->mc, map, name, NULL, now);

+			me = cache_lookup_distinct(map->mc, name);

+			if (me)

+				rv = cache_push_mapent(me, NULL);

+			else

+				rv = cache_update(map->mc, map, name, NULL, now);

 			if (rv != CHE_FAIL) {

 				me = cache_lookup_distinct(map->mc, name);

 				me->status = now + ap->negative_timeout;

--- autofs-5.0.7.orig/include/automount.h

+++ autofs-5.0.7/include/automount.h

@@ -146,6 +146,12 @@ struct mapent_cache {

 	struct mapent **hash;

 };

+struct stack {

+	char *mapent;

+	time_t age;

+	struct stack *next;

+};

+

 struct mapent {

 	struct mapent *next;

 	struct list_head ino_index;

@@ -159,6 +165,7 @@ struct mapent {

 	struct mapent *parent;

 	char *key;

 	char *mapent;

+	struct stack *stack;

 	time_t age;

 	/* Time of last mount fail */

 	time_t status;

@@ -175,6 +182,8 @@ void cache_readlock(struct mapent_cache

 void cache_writelock(struct mapent_cache *mc);

 int cache_try_writelock(struct mapent_cache *mc);

 void cache_unlock(struct mapent_cache *mc);

+int cache_push_mapent(struct mapent *me, char *mapent);

+int cache_pop_mapent(struct mapent *me);

 struct mapent_cache *cache_init(struct autofs_point *ap, struct map_source *map);

 struct mapent_cache *cache_init_null_cache(struct master *master);

 int cache_set_ino_index(struct mapent_cache *mc, const char *key, dev_t dev, ino_t ino);

--- autofs-5.0.7.orig/lib/cache.c

+++ autofs-5.0.7/lib/cache.c

@@ -177,6 +177,69 @@ static inline void ino_index_unlock(stru

 	return;

 }

+/* Save the cache entry mapent field onto a stack and set a new mapent */

+int cache_push_mapent(struct mapent *me, char *mapent)

+{

+	struct stack *s;

+	char *new;

+

+	if (!me->mapent)

+		return CHE_FAIL;

+

+	if (!mapent)

+		new = NULL;

+	else {

+		new = strdup(mapent);

+		if (!new)

+			return CHE_FAIL;

+	}

+

+	s = malloc(sizeof(struct stack));

+	if (!s) {

+		if (new)

+			free(new);

+		return CHE_FAIL;

+	}

+	memset(s, 0, sizeof(*s));

+

+	s->mapent = me->mapent;

+	s->age = me->age;

+	me->mapent = mapent;

+

+	if (me->stack)

+		s->next = me->stack;

+	me->stack = s;

+

+	return CHE_OK;

+}

+

+/* Restore cache entry mapent to a previously saved mapent, discard current */

+int cache_pop_mapent(struct mapent *me)

+{

+	struct stack *s = me->stack;

+	char *mapent;

+	time_t age;

+

+	if (!s || !s->mapent)

+		return CHE_FAIL;

+

+	mapent = s->mapent;

+	age = s->age;

+	me->stack = s->next;

+	free(s);

+

+	if (age < me->age) {

+		free(mapent);

+		return CHE_OK;

+	}

+

+	if (me->mapent)

+		free(me->mapent);

+	me->mapent = mapent;

+

+	return CHE_OK;

+}

+

 struct mapent_cache *cache_init(struct autofs_point *ap, struct map_source *map)

 {

 	struct mapent_cache *mc;

@@ -578,6 +641,8 @@ int cache_add(struct mapent_cache *mc, s

 	} else

 		me->mapent = NULL;

+	me->stack = NULL;

+

 	me->age = age;

 	me->status = 0;

 	me->mc = mc;

@@ -689,7 +754,9 @@ void cache_update_negative(struct mapent

 	int rv = CHE_OK;

 	me = cache_lookup_distinct(mc, key);

-	if (!me)

+	if (me)

+		rv = cache_push_mapent(me, NULL);

+	else

 		rv = cache_update(mc, ms, key, NULL, now);

 	if (rv != CHE_FAIL) {

 		me = cache_lookup_distinct(mc, key);

@@ -858,6 +925,7 @@ int cache_delete(struct mapent_cache *mc

 		pred = me;

 		me = me->next;

 		if (strcmp(this, me->key) == 0) {

+			struct stack *s = me->stack;

 			if (me->multi && !list_empty(&me->multi_list)) {

 				ret = CHE_FAIL;

 				goto done;

@@ -872,6 +940,13 @@ int cache_delete(struct mapent_cache *mc

 			free(me->key);

 			if (me->mapent)

 				free(me->mapent);

+			while (s) {

+				struct stack *next = s->next;

+				if (s->mapent)

+					free(s->mapent);

+				free(s);

+				s = next;

+			}

 			free(me);

 			me = pred;

 		}

@@ -882,6 +957,7 @@ int cache_delete(struct mapent_cache *mc

 		goto done;

 	if (strcmp(this, me->key) == 0) {

+		struct stack *s = me->stack;

 		if (me->multi && !list_empty(&me->multi_list)) {

 			ret = CHE_FAIL;

 			goto done;

@@ -896,6 +972,13 @@ int cache_delete(struct mapent_cache *mc

 		free(me->key);

 		if (me->mapent)

 			free(me->mapent);

+		while (s) {

+			struct stack *next = s->next;

+			if (s->mapent)

+				free(s->mapent);

+			free(s);

+			s = next;

+		}

 		free(me);

 	}

 done:

--- autofs-5.0.7.orig/modules/lookup_file.c

+++ autofs-5.0.7/modules/lookup_file.c

@@ -988,8 +988,10 @@ int lookup_mount(struct autofs_point *ap

 				cache_writelock(smc);

 				sme = cache_lookup_distinct(smc, key);

 				/* Negative timeout expired for non-existent entry. */

-				if (sme && !sme->mapent)

-					cache_delete(smc, key);

+				if (sme && !sme->mapent) {

+					if (cache_pop_mapent(sme) == CHE_FAIL)

+						cache_delete(smc, key);

+				}

 				cache_unlock(smc);

 			}

 		}

--- autofs-5.0.7.orig/modules/lookup_hosts.c

+++ autofs-5.0.7/modules/lookup_hosts.c

@@ -155,7 +155,9 @@ static int do_parse_mount(struct autofs_

 		cache_writelock(mc);

 		me = cache_lookup_distinct(mc, name);

-		if (!me)

+		if (me)

+			rv = cache_push_mapent(me, NULL);

+		else

 			rv = cache_update(mc, source, name, NULL, now);

 		if (rv != CHE_FAIL) {

 			me = cache_lookup_distinct(mc, name);

@@ -315,8 +317,10 @@ int lookup_mount(struct autofs_point *ap

 				cache_writelock(smc);

 				sme = cache_lookup_distinct(smc, name);

 				/* Negative timeout expired for non-existent entry. */

-				if (sme && !sme->mapent)

-					cache_delete(smc, name);

+				if (sme && !sme->mapent) {

+					if (cache_pop_mapent(sme) == CHE_FAIL)

+						cache_delete(smc, name);

+				}

 				cache_unlock(smc);

 			}

 		}

--- autofs-5.0.7.orig/modules/lookup_ldap.c

+++ autofs-5.0.7/modules/lookup_ldap.c

@@ -2937,8 +2937,10 @@ int lookup_mount(struct autofs_point *ap

 				cache_writelock(smc);

 				sme = cache_lookup_distinct(smc, key);

 				/* Negative timeout expired for non-existent entry. */

-				if (sme && !sme->mapent)

-					cache_delete(smc, key);

+				if (sme && !sme->mapent) {

+					if (cache_pop_mapent(sme) == CHE_FAIL)

+						cache_delete(smc, key);

+				}

 				cache_unlock(smc);

 			}

 		}

--- autofs-5.0.7.orig/modules/lookup_nisplus.c

+++ autofs-5.0.7/modules/lookup_nisplus.c

@@ -509,8 +509,10 @@ int lookup_mount(struct autofs_point *ap

 				cache_writelock(smc);

 				sme = cache_lookup_distinct(smc, key);

 				/* Negative timeout expired for non-existent entry. */

-				if (sme && !sme->mapent)

-					cache_delete(smc, key);

+				if (sme && !sme->mapent) {

+					if (cache_pop_mapent(sme) == CHE_FAIL)

+						cache_delete(smc, key);

+				}

 				cache_unlock(smc);

 			}

 		}

@@ -602,7 +604,9 @@ int lookup_mount(struct autofs_point *ap

 			return NSS_STATUS_TRYAGAIN;

 		cache_writelock(mc);

 		me = cache_lookup_distinct(mc, key);

-		if (!me)

+		if (me)

+			rv = cache_push_mapent(me, NULL);

+		else

 			rv = cache_update(mc, source, key, NULL, now);

 		if (rv != CHE_FAIL) {

 			me = cache_lookup_distinct(mc, key);

--- autofs-5.0.7.orig/modules/lookup_program.c

+++ autofs-5.0.7/modules/lookup_program.c

@@ -156,8 +156,10 @@ int lookup_mount(struct autofs_point *ap

 				cache_writelock(smc);

 				sme = cache_lookup_distinct(smc, name);

 				/* Negative timeout expired for non-existent entry. */

-				if (sme && !sme->mapent)

-					cache_delete(smc, name);

+				if (sme && !sme->mapent) {

+					if (cache_pop_mapent(sme) == CHE_FAIL)

+						cache_delete(smc, name);

+				}

 				cache_unlock(smc);

 			}

 		}

@@ -451,7 +453,9 @@ out_free:

 		cache_writelock(mc);

 		me = cache_lookup_distinct(mc, name);

-		if (!me)

+		if (me)

+			rv = cache_push_mapent(me, NULL);

+		else

 			rv = cache_update(mc, source, name, NULL, now);

 		if (rv != CHE_FAIL) {

 			me = cache_lookup_distinct(mc, name);

--- autofs-5.0.7.orig/modules/lookup_sss.c

+++ autofs-5.0.7/modules/lookup_sss.c

@@ -599,8 +599,10 @@ int lookup_mount(struct autofs_point *ap

 				cache_writelock(smc);

 				sme = cache_lookup_distinct(smc, key);

 				/* Negative timeout expired for non-existent entry. */

-				if (sme && !sme->mapent)

-					cache_delete(smc, key);

+				if (sme && !sme->mapent) {

+					if (cache_pop_mapent(sme) == CHE_FAIL)

+						cache_delete(smc, key);

+				}

 				cache_unlock(smc);

 			}

 		}

--- autofs-5.0.7.orig/modules/lookup_yp.c

+++ autofs-5.0.7/modules/lookup_yp.c

@@ -613,8 +613,10 @@ int lookup_mount(struct autofs_point *ap

 				cache_writelock(smc);

 				sme = cache_lookup_distinct(smc, key);

 				/* Negative timeout expired for non-existent entry. */

-				if (sme && !sme->mapent)

-					cache_delete(smc, key);

+				if (sme && !sme->mapent) {

+					if (cache_pop_mapent(sme) == CHE_FAIL)

+						cache_delete(smc, key);

+				}

 				cache_unlock(smc);

 			}

 		}