autofs/autofs-5.1.7-fix-direct-mount-deadlock.patch

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autofs-5.1.7 - fix direct mount deadlock
From: Ian Kent <raven@themaw.net>
When umounting direct mounts at exit or when umounting mounts no
longer in the map on re-load a deadlock can occur.
Signed-off-by: Ian Kent <raven@themaw.net>
---
CHANGELOG | 1 +
daemon/direct.c | 22 +++++++++++++++++++++-
daemon/state.c | 14 +++++++++-----
3 files changed, 31 insertions(+), 6 deletions(-)
--- autofs-5.1.7.orig/CHANGELOG
+++ autofs-5.1.7/CHANGELOG
@@ -73,6 +73,7 @@
- use mapent tree root for tree_mapent_add_node().
- eliminate redundant cache lookup in tree_mapent_add_node().
- fix hosts map offset order.
+- fix direct mount deadlock.
25/01/2021 autofs-5.1.7
- make bind mounts propagation slave by default.
--- autofs-5.1.7.orig/daemon/direct.c
+++ autofs-5.1.7/daemon/direct.c
@@ -84,11 +84,27 @@ static void mnts_cleanup(void *arg)
int do_umount_autofs_direct(struct autofs_point *ap, struct mapent *me)
{
struct ioctl_ops *ops = get_ioctl_ops();
+ struct mapent_cache *mc = me->mc;
char buf[MAX_ERR_BUF];
int ioctlfd = -1, rv, left, retries;
+ char key[PATH_MAX + 1];
+ struct mapent *tmp;
int opened = 0;
- left = umount_multi(ap, me->key, 0);
+ if (me->len > PATH_MAX) {
+ error(ap->logopt, "path too long");
+ return 1;
+ }
+ strcpy(key, me->key);
+
+ cache_unlock(mc);
+ left = umount_multi(ap, key, 0);
+ cache_readlock(mc);
+ tmp = cache_lookup_distinct(mc, key);
+ if (tmp != me) {
+ error(ap->logopt, "key %s no longer in mapent cache", key);
+ return -1;
+ }
if (left) {
warn(ap->logopt, "could not unmount %d dirs under %s",
left, me->key);
@@ -213,6 +229,7 @@ int umount_autofs_direct(struct autofs_p
mc = map->mc;
pthread_cleanup_push(cache_lock_cleanup, mc);
cache_readlock(mc);
+restart:
me = cache_enumerate(mc, NULL);
while (me) {
int error;
@@ -230,6 +247,9 @@ int umount_autofs_direct(struct autofs_p
* failed umount.
*/
error = do_umount_autofs_direct(ap, me);
+ /* cache became invalid, restart */
+ if (error == -1)
+ goto restart;
if (!error)
goto done;
--- autofs-5.1.7.orig/daemon/state.c
+++ autofs-5.1.7/daemon/state.c
@@ -324,11 +324,12 @@ static void do_readmap_cleanup(void *arg
return;
}
-static void do_readmap_mount(struct autofs_point *ap,
+static int do_readmap_mount(struct autofs_point *ap,
struct map_source *map, struct mapent *me, time_t now)
{
struct mapent_cache *nc;
struct mapent *ne, *nested, *valid;
+ int ret = 0;
nc = ap->entry->master->nc;
@@ -387,7 +388,7 @@ static void do_readmap_mount(struct auto
cache_unlock(vmc);
error(ap->logopt,
"failed to find expected existing valid map entry");
- return;
+ return ret;
}
/* Take over the mount if there is one */
valid->ioctlfd = me->ioctlfd;
@@ -406,14 +407,14 @@ static void do_readmap_mount(struct auto
ap->exp_runfreq = runfreq;
}
} else if (!is_mounted(me->key, MNTS_REAL))
- do_umount_autofs_direct(ap, me);
+ ret = do_umount_autofs_direct(ap, me);
else
debug(ap->logopt,
"%s is mounted", me->key);
} else
do_mount_autofs_direct(ap, me, get_exp_timeout(ap, map));
- return;
+ return ret;
}
static void *do_readmap(void *arg)
@@ -480,9 +481,12 @@ static void *do_readmap(void *arg)
mc = map->mc;
pthread_cleanup_push(cache_lock_cleanup, mc);
cache_readlock(mc);
+restart:
me = cache_enumerate(mc, NULL);
while (me) {
- do_readmap_mount(ap, map, me, now);
+ int ret = do_readmap_mount(ap, map, me, now);
+ if (ret == -1)
+ goto restart;
me = cache_enumerate(mc, me);
}
lookup_prune_one_cache(ap, map->mc, now);