[PATCH] autofs4: need to invalidate children on tree mount expire

I've found a case where invalid dentrys in a mount tree, waiting to be
cleaned up by d_invalidate, prevent the expected expire.

In this case dentrys created during a lookup for which a mount fails or has
no entry in the mount map contribute to the d_count of the parent dentry.
These dentrys may not be invalidated prior to comparing the interanl usage
count of valid autofs dentrys against the dentry d_count which makes a
mount tree appear busy so it doesn't expire.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index b8ce02607d66..4456d1daa40f 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -174,6 +174,12 @@ static int autofs4_tree_busy(struct vfsmount *mnt,
                         struct autofs_info *ino = autofs4_dentry_ino(p);
                         unsigned int ino_count = atomic_read(&ino->count);
 
+                        /*
+                         * Clean stale dentries below that have not been
+                         * invalidated after a mount fail during lookup
+                         */
+                        d_invalidate(p);
+
                         /* allow for dget above and top is already dgot */
                         if (p == top)
                                 ino_count += 2;