autofs4: correct offset mount expire check
When checking a directory tree in autofs_tree_busy() we can incorrectly
decide that the tree isn't busy. This happens for the case of an active
offset mount as autofs4_follow_mount() follows past the active offset
mount, which has an open file handle used for expires, causing the file
handle not to count toward the busyness check.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index cde2f8e..4b6fb3f 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -56,12 +56,23 @@
mntget(mnt);
dget(dentry);
- if (!autofs4_follow_mount(&mnt, &dentry))
+ if (!follow_down(&mnt, &dentry))
goto done;
- /* This is an autofs submount, we can't expire it */
- if (is_autofs4_dentry(dentry))
- goto done;
+ if (is_autofs4_dentry(dentry)) {
+ struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+
+ /* This is an autofs submount, we can't expire it */
+ if (sbi->type == AUTOFS_TYPE_INDIRECT)
+ goto done;
+
+ /*
+ * Otherwise it's an offset mount and we need to check
+ * if we can umount its mount, if there is one.
+ */
+ if (!d_mountpoint(dentry))
+ goto done;
+ }
/* Update the expiry counter if fs is busy */
if (!may_umount_tree(mnt)) {