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authorIan Kent <raven@themaw.net>2008-07-23 21:30:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-24 10:47:32 -0700
commit6e60a9ab5f5d314735467752f623072f5b75157a (patch)
tree1a42df40e6fad52bd6be74970af8eb56870fe6ba /fs/autofs4/autofs_i.h
parent97e7449a7ad883bf9f516fc970778d75999c7843 (diff)
downloadlinux-linaro-6e60a9ab5f5d314735467752f623072f5b75157a.tar.gz
autofs4: fix direct mount pending expire race
For direct and offset type mounts that are covered by another mount we cannot check the AUTOFS_INF_EXPIRING flag during a path walk which leads to lookups walking into an expiring mount while it is being expired. For example, for the direct multi-mount map entry with a couple of offsets: /race/mm1 / <server1>:/<path1> /om1 <server2>:/<path2> /om2 <server1>:/<path3> an autofs trigger mount is mounted on /race/mm1 and when accessed it is over mounted and trigger mounts made for /race/mm1/om1 and /race/mm1/om2. So it isn't possible for path walks to see the expiring flag at all and they happily walk into the file system while it is expiring. When expiring these mounts follow_down() must stop at the autofs mount and all processes must block in the ->follow_link() method (except the daemon) until the expire is complete. This is done by decrementing the d_mounted field of the autofs trigger mount root dentry until the expire is completed. In ->follow_link() all processes wait on the expire and the mount following is completed for the daemon until the expire is complete. Signed-off-by: Ian Kent <raven@themaw.net> Cc: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/autofs4/autofs_i.h')
-rw-r--r--fs/autofs4/autofs_i.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index 5d90ed3b4b4..4b40cbc71e9 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -52,6 +52,8 @@ struct autofs_info {
int flags;
+ struct completion expire_complete;
+
struct list_head active;
struct list_head expiring;
@@ -69,6 +71,7 @@ struct autofs_info {
};
#define AUTOFS_INF_EXPIRING (1<<0) /* dentry is in the process of expiring */
+#define AUTOFS_INF_MOUNTPOINT (1<<1) /* mountpoint status for direct expire */
struct autofs_wait_queue {
wait_queue_head_t queue;