autofs - remove autofs dentry mount check

When checking if an autofs mount point is busy it isn't sufficient to
only check if it's a mount point.

For example, if the mount of an offset mountpoint in a tree is denied
for this host by its export and the dentry becomes a process working
directory the check incorrectly returns the mount as not in use at
expire.

This can happen since the default when mounting within a tree is
nostrict, which means ingnore mount fails on mounts within the tree and
continue.  The nostrict option is meant to allow mounting in this case.

Signed-off-by: David Jeffery <djeffery@redhat.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 9 deletions

diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 01443ce43ee7..13ddec92341c 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -61,15 +61,6 @@ static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
                 /* This is an autofs submount, we can't expire it */
                 if (autofs_type_indirect(sbi->type))
                         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(path.dentry)) {
-                        status = 0;
-                        goto done;
-                }
         }
 
         /* Update the expiry counter if fs is busy */