autofs-5.0.5 - fix remount locking

From: Ian Kent <raven@themaw.net>

When autofs is restarted with active mounts it is possible, due

to possible recursion when mounting multi-mount map entries, that

a lookup module will take a write lock on the map entry cache

when a read lock is alreay held.

Since, during the re-mount, we are still essentially running

single threaded we need only take care to ensure we don't take

the write lock.

---

 CHANGELOG                |    1 +

 modules/lookup_file.c    |   27 +++++++++++++++++----------

 modules/lookup_hosts.c   |   24 +++++++++++++++---------

 modules/lookup_ldap.c    |   24 ++++++++++++++++--------

 modules/lookup_nisplus.c |   29 ++++++++++++++++++-----------

 modules/lookup_program.c |   29 +++++++++++++++++++++--------

 modules/lookup_yp.c      |   27 +++++++++++++++++----------

 7 files changed, 105 insertions(+), 56 deletions(-)

--- autofs-5.0.5.orig/CHANGELOG

+++ autofs-5.0.5/CHANGELOG

@@ -33,6 +33,7 @@

 - fix random selection for host on different network.

 - make redhat init script more lsb compliant.

 - don't hold lock for simple mounts.

+- fix remount locking.

 03/09/2009 autofs-5.0.5

 -----------------------

--- autofs-5.0.5.orig/modules/lookup_file.c

+++ autofs-5.0.5/modules/lookup_file.c

@@ -871,7 +871,6 @@ static int check_map_indirect(struct aut

 	if (ret == CHE_FAIL)

 		return NSS_STATUS_NOTFOUND;

-	pthread_cleanup_push(cache_lock_cleanup, mc);

 	cache_writelock(mc);

 	exists = cache_lookup_distinct(mc, key);

 	/* Not found in the map but found in the cache */

@@ -882,7 +881,7 @@ static int check_map_indirect(struct aut

 			exists->status = 0;

 		}

 	}

-	pthread_cleanup_pop(1);

+	cache_unlock(mc);

 	if (ret == CHE_MISSING) {

 		struct mapent *we;

@@ -896,7 +895,6 @@ static int check_map_indirect(struct aut

 		 * Check for map change and update as needed for

 		 * following cache lookup.

 		 */

-		pthread_cleanup_push(cache_lock_cleanup, mc);

 		cache_writelock(mc);

 		we = cache_lookup_distinct(mc, "*");

 		if (we) {

@@ -904,7 +902,7 @@ static int check_map_indirect(struct aut

 			if (we->source == source && (wild & CHE_MISSING))

 				cache_delete(mc, "*");

 		}

-		pthread_cleanup_pop(1);

+		cache_unlock(mc);

 		if (wild & (CHE_OK | CHE_UPDATED))

 			return NSS_STATUS_SUCCESS;

@@ -957,13 +955,22 @@ int lookup_mount(struct autofs_point *ap

 		if (me->status >= time(NULL)) {

 			cache_unlock(me->mc);

 			return NSS_STATUS_NOTFOUND;

+		} else {

+			struct mapent_cache *smc = me->mc;

+			struct mapent *sme;

+

+			if (me->mapent)

+				cache_unlock(smc);

+			else {

+				cache_unlock(smc);

+				cache_writelock(smc);

+				sme = cache_lookup_distinct(smc, key);

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

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

+					cache_delete(smc, key);

+				cache_unlock(smc);

+			}

 		}

-

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

-		if (!me->mapent)

-			cache_delete(me->mc, key);

-

-		cache_unlock(me->mc);

 	}

 	/*

--- autofs-5.0.5.orig/modules/lookup_hosts.c

+++ autofs-5.0.5/modules/lookup_hosts.c

@@ -146,19 +146,25 @@ int lookup_mount(struct autofs_point *ap

 	/* Check if we recorded a mount fail for this key anywhere */

 	me = lookup_source_mapent(ap, name, LKP_DISTINCT);

 	if (me) {

-		struct mapent_cache *fmc = me->mc;

-

 		if (me->status >= time(NULL)) {

-			cache_unlock(fmc);

+			cache_unlock(me->mc);

 			return NSS_STATUS_NOTFOUND;

-		}

+		} else {

+			struct mapent_cache *smc = me->mc;

+			struct mapent *sme;

-		if (!me->mapent) {

-			cache_delete(fmc, name);

-			me = NULL;

+			if (me->mapent)

+				cache_unlock(smc);

+			else {

+				cache_unlock(smc);

+				cache_writelock(smc);

+				sme = cache_lookup_distinct(smc, name);

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

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

+					cache_delete(smc, name);

+				cache_unlock(smc);

+			}

 		}

-

-		cache_unlock(fmc);

 	}

 	cache_readlock(mc);

--- autofs-5.0.5.orig/modules/lookup_ldap.c

+++ autofs-5.0.5/modules/lookup_ldap.c

@@ -2681,7 +2681,6 @@ next:

 	unbind_ldap_connection(ap->logopt, ldap, ctxt);

 	/* Failed to find wild entry, update cache if needed */

-	pthread_cleanup_push(cache_lock_cleanup, mc);

 	cache_writelock(mc);

 	we = cache_lookup_distinct(mc, "*");

 	if (we) {

@@ -2707,7 +2706,7 @@ next:

 			}

 		}

 	}

-	pthread_cleanup_pop(1);

+	cache_unlock(mc);

 	free(query);

 	return ret;

@@ -2817,13 +2816,22 @@ int lookup_mount(struct autofs_point *ap

 		if (me->status >= time(NULL)) {

 			cache_unlock(me->mc);

 			return NSS_STATUS_NOTFOUND;

+		} else {

+			struct mapent_cache *smc = me->mc;

+			struct mapent *sme;

+

+			if (me->mapent)

+				cache_unlock(smc);

+			else {

+				cache_unlock(smc);

+				cache_writelock(smc);

+				sme = cache_lookup_distinct(smc, key);

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

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

+					cache_delete(smc, key);

+				cache_unlock(smc);

+			}

 		}

-

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

-		if (!me->mapent)

-			cache_delete(me->mc, key);

-

-		cache_unlock(me->mc);

 	}

         /*

--- autofs-5.0.5.orig/modules/lookup_nisplus.c

+++ autofs-5.0.5/modules/lookup_nisplus.c

@@ -421,7 +421,6 @@ static int check_map_indirect(struct aut

 		return NSS_STATUS_UNAVAIL;

 	}

-	pthread_cleanup_push(cache_lock_cleanup, mc);

 	cache_writelock(mc);

 	t_last_read = ap->exp_runfreq + 1;

 	me = cache_lookup_first(mc);

@@ -442,8 +441,8 @@ static int check_map_indirect(struct aut

 			exists->status = 0;

 		}

 	}

-	pthread_cleanup_pop(1);

-	

+	cache_unlock(mc);

+

 	if (t_last_read > ap->exp_runfreq && ret & CHE_UPDATED)

 		source->stale = 1;

@@ -459,7 +458,6 @@ static int check_map_indirect(struct aut

 		 * Check for map change and update as needed for

 		 * following cache lookup.

 		*/

-		pthread_cleanup_push(cache_lock_cleanup, mc);

 		cache_writelock(mc);

 		we = cache_lookup_distinct(mc, "*");

 		if (we) {

@@ -473,7 +471,7 @@ static int check_map_indirect(struct aut

 			if (wild & (CHE_OK | CHE_UPDATED))

 				source->stale = 1;

 		}

-		pthread_cleanup_pop(1);

+		cache_unlock(mc);

 		if (wild & (CHE_UPDATED | CHE_OK))

 			return NSS_STATUS_SUCCESS;

@@ -516,13 +514,22 @@ int lookup_mount(struct autofs_point *ap

 		if (me->status >= time(NULL)) {

 			cache_unlock(me->mc);

 			return NSS_STATUS_NOTFOUND;

-		}

-

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

-		if (!me->mapent)

-			cache_delete(me->mc, key);

+		} else {

+			struct mapent_cache *smc = me->mc;

+			struct mapent *sme;

-		cache_unlock(me->mc);

+			if (me->mapent)

+				cache_unlock(smc);

+			else {

+				cache_unlock(smc);

+				cache_writelock(smc);

+				sme = cache_lookup_distinct(smc, key);

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

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

+					cache_delete(smc, key);

+				cache_unlock(smc);

+			}

+		}

 	}

 	/*

--- autofs-5.0.5.orig/modules/lookup_program.c

+++ autofs-5.0.5/modules/lookup_program.c

@@ -135,17 +135,26 @@ int lookup_mount(struct autofs_point *ap

 		if (me->status >= time(NULL)) {

 			cache_unlock(me->mc);

 			return NSS_STATUS_NOTFOUND;

-		}

-

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

-		if (!me->mapent)

-			cache_delete(me->mc, name);

+		} else {

+			struct mapent_cache *smc = me->mc;

+			struct mapent *sme;

-		cache_unlock(me->mc);

+			if (me->mapent)

+				cache_unlock(smc);

+			else {

+				cache_unlock(smc);

+				cache_writelock(smc);

+				sme = cache_lookup_distinct(smc, name);

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

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

+					cache_delete(smc, name);

+				cache_unlock(smc);

+			}

+		}

 	}

 	/* Catch installed direct offset triggers */

-	cache_writelock(mc);

+	cache_readlock(mc);

 	me = cache_lookup_distinct(mc, name);

 	if (!me) {

 		cache_unlock(mc);

@@ -191,7 +200,11 @@ int lookup_mount(struct autofs_point *ap

 				     " key %s, returning fail", name);

 				return NSS_STATUS_UNAVAIL;

 			}

-			cache_delete(mc, name);

+			cache_unlock(mc);

+			cache_writelock(mc);

+			me = cache_lookup_distinct(mc, name);

+			if (me)

+				cache_delete(mc, name);

 			cache_unlock(mc);

 		}

 	}

--- autofs-5.0.5.orig/modules/lookup_yp.c

+++ autofs-5.0.5/modules/lookup_yp.c

@@ -533,7 +533,6 @@ static int check_map_indirect(struct aut

 		source->stale = 1;

 	}

-	pthread_cleanup_push(cache_lock_cleanup, mc);

 	cache_writelock(mc);

 	exists = cache_lookup_distinct(mc, key);

 	/* Not found in the map but found in the cache */

@@ -545,7 +544,7 @@ static int check_map_indirect(struct aut

 			exists->status = 0;

 		}

 	}

-	pthread_cleanup_pop(1);

+	cache_unlock(mc);

 	if (ret == CHE_MISSING) {

 		struct mapent *we;

@@ -559,7 +558,6 @@ static int check_map_indirect(struct aut

 		 * Check for map change and update as needed for

 		 * following cache lookup.

 		 */

-		pthread_cleanup_push(cache_lock_cleanup, mc);

 		cache_writelock(mc);

 		we = cache_lookup_distinct(mc, "*");

 		if (we) {

@@ -573,7 +571,7 @@ static int check_map_indirect(struct aut

 			if (wild & (CHE_OK | CHE_UPDATED))

 				source->stale = 1;

 		}

-		pthread_cleanup_pop(1);

+		cache_unlock(mc);

 		if (wild & (CHE_OK | CHE_UPDATED))

 			return NSS_STATUS_SUCCESS;

@@ -616,13 +614,22 @@ int lookup_mount(struct autofs_point *ap

 		if (me->status >= time(NULL)) {

 			cache_unlock(me->mc);

 			return NSS_STATUS_NOTFOUND;

-		}

-

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

-		if (!me->mapent)

-			cache_delete(me->mc, key);

+		} else {

+			struct mapent_cache *smc = me->mc;

+			struct mapent *sme;

-		cache_unlock(me->mc);

+			if (me->mapent)

+				cache_unlock(smc);

+			else {

+				cache_unlock(smc);

+				cache_writelock(smc);

+				sme = cache_lookup_distinct(smc, key);

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

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

+					cache_delete(smc, key);

+				cache_unlock(smc);

+			}

+		}

 	}

 	 /*