autofs-5.1.7 - eliminate clean_stale_multi_triggers()

From: Ian Kent <raven@themaw.net>

Eliminate clean_stale_multi_triggers() by checking for stale offsets at

the time mount_subtree() is called.

This should result in the same behaviour but eliminate an additional

seperate traversal of the offset list.

Signed-off-by: Ian Kent <raven@themaw.net>

---

 CHANGELOG           |    1 

 lib/mounts.c        |  209 ++++++++++-----------------------------------------

 modules/parse_sun.c |   10 --

 3 files changed, 43 insertions(+), 177 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG

index 5a3bedc1..b1ce7b69 100644

--- a/CHANGELOG

+++ b/CHANGELOG

@@ -12,6 +12,7 @@

 - remove redundant variables from mount_autofs_offset().

 - remove unused parameter form do_mount_autofs_offset().

 - refactor umount_multi_triggers().

+- eliminate clean_stale_multi_triggers().

 25/01/2021 autofs-5.1.7

 - make bind mounts propagation slave by default.

diff --git a/lib/mounts.c b/lib/mounts.c

index 5268ba5b..a9abbebf 100644

--- a/lib/mounts.c

+++ b/lib/mounts.c

@@ -2601,10 +2601,44 @@ static int do_umount_offset(struct autofs_point *ap, struct mapent *oe, const ch

 	oe_base = oe->key + strlen(root);

 	left += do_umount_multi_triggers(ap, oe, root, oe_base);

+	/*

+	 * If an offset that has an active mount has been removed

+	 * from the multi-mount we don't want to attempt to trigger

+	 * mounts for it. Obviously this is because it has been

+	 * removed, but less obvious is the potential strange

+	 * behaviour that can result if we do try and mount it

+	 * again after it's been expired. For example, if an NFS

+	 * file system is no longer exported and is later umounted

+	 * it can be mounted again without any error message but

+	 * shows as an empty directory. That's going to confuse

+	 * people for sure.

+	 *

+	 * If the mount cannot be umounted (the process is now

+	 * using a stale mount) the offset needs to be invalidated

+	 * so no further mounts will be attempted but the offset

+	 * cache entry must remain so expires can continue to

+	 * attempt to umount it. If the mount can be umounted and

+	 * the offset is removed, at least for NFS we will get

+	 * ESTALE errors when attempting list the directory.

+	 */

 	if (oe->ioctlfd != -1 ||

 	    is_mounted(oe->key, MNTS_REAL)) {

-		left++;

-		return left;

+		if (umount_ent(ap, oe->key) &&

+		    is_mounted(oe->key, MNTS_REAL)) {

+			debug(ap->logopt,

+			      "offset %s has active mount, invalidate",

+			      oe->key);

+			/*

+			 * Ok, so we shouldn't modify the mapent but

+			 * mount requests are blocked at a point above

+			 * this and expire only uses the mapent key.

+			 */

+			if (oe->mapent) {

+				free(oe->mapent);

+				oe->mapent = NULL;

+			}

+			return ++left;

+		}

 	}

 	debug(ap->logopt, "umount offset %s", oe->key);

@@ -2666,6 +2700,11 @@ int mount_multi_triggers(struct autofs_point *ap, struct mapent *me,

 		oe = cache_lookup_distinct(me->mc, key);

 		if (!oe || !oe->mapent)

 			goto cont;

+		if (oe->age != me->multi->age) {

+			/* Best effort */

+			do_umount_offset(ap, oe, root);

+			goto cont;

+		}

 		mounted += do_mount_autofs_offset(ap, oe, root);

@@ -2725,169 +2764,3 @@ int umount_multi_triggers(struct autofs_point *ap, struct mapent *me, char *root

 	return left;

 }

-

-int clean_stale_multi_triggers(struct autofs_point *ap,

-			       struct mapent *me, char *top, const char *base)

-{

-	char *root;

-	char mm_top[PATH_MAX + 1];

-	char path[PATH_MAX + 1];

-	char *offset;

-	struct mapent *oe;

-	struct list_head *mm_root, *pos;

-	const char o_root[] = "/";

-	const char *mm_base;

-	int left, start;

-	unsigned int root_len;

-	unsigned int mm_base_len;

-	time_t age;

-

-	if (top)

-		root = top;

-	else {

-		if (!strchr(me->multi->key, '/'))

-			/* Indirect multi-mount root */

-			/* sprintf okay - if it's mounted, it's

-			 * PATH_MAX or less bytes */

-			sprintf(mm_top, "%s/%s", ap->path, me->multi->key);

-		else

-			strcpy(mm_top, me->multi->key);

-		root = mm_top;

-	}

-

-	left = 0;

-	start = strlen(root);

-

-	mm_root = &me->multi->multi_list;

-

-	if (!base)

-		mm_base = o_root;

-	else

-		mm_base = base;

-

-	pos = NULL;

-	offset = path;

-	root_len = start;

-	mm_base_len = strlen(mm_base);

-	age = me->multi->age;

-

-	while ((offset = cache_get_offset(mm_base, offset, start, mm_root, &pos))) {

-		char key[PATH_MAX + 1];

-		int key_len = root_len + strlen(offset);

-		char *oe_base;

-		int ret;

-

-		if (mm_base_len > 1)

-			key_len += mm_base_len;

-

-		if (key_len > PATH_MAX) {

-			warn(ap->logopt, "path loo long");

-			continue;

-		}

-

-		strcpy(key, root);

-		if (mm_base_len > 1)

-			strcat(key, mm_base);

-		strcat(key, offset);

-

-		oe = cache_lookup_distinct(me->mc, key);

-		/* root offset is a special case */

-		if (!oe || (strlen(oe->key) - start) == 1)

-			continue;

-

-		/* Check for and umount stale subtree offsets */

-		oe_base = oe->key + strlen(root);

-		ret = clean_stale_multi_triggers(ap, oe, root, oe_base);

-		left += ret;

-		if (ret)

-			continue;

-

-		if (oe->age == age)

-			continue;

-

-		/*

-		 * If an offset that has an active mount has been removed

-		 * from the multi-mount we don't want to attempt to trigger

-		 * mounts for it. Obviously this is because it has been

-		 * removed, but less obvious is the potential strange

-		 * behaviour that can result if we do try and mount it

-		 * again after it's been expired. For example, if an NFS

-		 * file system is no longer exported and is later umounted

-		 * it can be mounted again without any error message but

-		 * shows as an empty directory. That's going to confuse

-		 * people for sure.

-		 *

-		 * If the mount cannot be umounted (the process is now

-		 * using a stale mount) the offset needs to be invalidated

-		 * so no further mounts will be attempted but the offset

-		 * cache entry must remain so expires can continue to

-		 * attempt to umount it. If the mount can be umounted and

-		 * the offset is removed, at least for NFS we will get

-		 * ESTALE errors when attempting list the directory.

-		 */

-		if (oe->ioctlfd != -1 ||

-		    is_mounted(oe->key, MNTS_REAL)) {

-			if (umount_ent(ap, oe->key) &&

-			    is_mounted(oe->key, MNTS_REAL)) {

-				debug(ap->logopt,

-				      "offset %s has active mount, invalidate",

-				      oe->key);

-				if (oe->mapent) {

-					free(oe->mapent);

-					oe->mapent = NULL;

-				}

-				left++;

-				continue;

-			}

-		}

-

-		debug(ap->logopt, "umount offset %s", oe->key);

-

-		if (umount_autofs_offset(ap, oe)) {

-			warn(ap->logopt, "failed to umount offset %s", key);

-			left++;

-		} else {

-			struct stat st;

-

-			/* Mount point not ours to delete ? */

-			if (!(oe->flags & MOUNT_FLAG_DIR_CREATED)) {

-				debug(ap->logopt, "delete offset key %s", key);

-				if (cache_delete_offset(oe->mc, key) == CHE_FAIL)

-					error(ap->logopt,

-					     "failed to delete offset key %s", key);

-				continue;

-			}

-

-			/*

-			 * An error due to partial directory removal is

-			 * ok so only try and remount the offset if the

-			 * actual mount point still exists.

-			 */

-			ret = rmdir_path_offset(ap, oe);

-			if (ret == -1 && !stat(oe->key, &st)) {

-				ret = do_mount_autofs_offset(ap, oe, root);

-				if (ret) {

-					left++;

-					/* But we did origianlly create this */

-					oe->flags |= MOUNT_FLAG_DIR_CREATED;

-					continue;

-				}

-				/*

-				 * Fall through if the trigger can't be mounted

-				 * again, since there is no offset there can't

-				 * be any mount requests so remove the map

-				 * entry from the cache. There's now a dead

-				 * offset mount, but what else can we do ....

-				 */

-			}

-

-			debug(ap->logopt, "delete offset key %s", key);

-

-			if (cache_delete_offset(oe->mc, key) == CHE_FAIL)

-				error(ap->logopt,

-				     "failed to delete offset key %s", key);

-		}

-	}

-

-	return left;

-}

diff --git a/modules/parse_sun.c b/modules/parse_sun.c

index f42af7b7..f4d5125c 100644

--- a/modules/parse_sun.c

+++ b/modules/parse_sun.c

@@ -1176,7 +1176,7 @@ static int mount_subtree(struct autofs_point *ap, struct mapent *me,

 		/* Mount root offset if it exists */

 		ro = cache_lookup_distinct(me->mc, key);

-		if (ro) {

+		if (ro && ro->age == me->multi->age) {

 			char *myoptions, *ro_loc;

 			int namelen = name ? strlen(name) : 0;

 			int ro_len;

@@ -1610,14 +1610,6 @@ dont_expand:

 			free(myoptions);

 		} while (*p == '/' || (*p == '"' && *(p + 1) == '/'));

-		/*

-		 * We've got the ordered list of multi-mount entries so go

-		 * through and remove any stale entries if this is the top

-		 * of the multi-mount and set the parent entry of each.

-		 */

-		if (me == me->multi)

-			clean_stale_multi_triggers(ap, me, NULL, NULL);

-

 		rv = mount_subtree(ap, me, name, NULL, options, ctxt);

 		cache_multi_unlock(me);