mnt: Update detach_mounts to leave mounts connected
Now that it is possible to lazily unmount an entire mount tree and
leave the individual mounts connected to each other add a new flag
UMOUNT_CONNECTED to umount_tree to force this behavior and use
this flag in detach_mounts.
This closes a bug where the deletion of a file or directory could
trigger an unmount and reveal data under a mount point.
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/fs/namespace.c b/fs/namespace.c
index e8f7f8c..1f4f9da 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1348,6 +1348,7 @@
enum umount_tree_flags {
UMOUNT_SYNC = 1,
UMOUNT_PROPAGATE = 2,
+ UMOUNT_CONNECTED = 4,
};
/*
* mount_lock must be held
@@ -1386,7 +1387,10 @@
if (how & UMOUNT_SYNC)
p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;
- disconnect = !IS_MNT_LOCKED_AND_LAZY(p);
+ disconnect = !(((how & UMOUNT_CONNECTED) &&
+ mnt_has_parent(p) &&
+ (p->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) ||
+ IS_MNT_LOCKED_AND_LAZY(p));
pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt,
disconnect ? &unmounted : NULL);
@@ -1529,7 +1533,7 @@
umount_mnt(p);
}
}
- else umount_tree(mnt, 0);
+ else umount_tree(mnt, UMOUNT_CONNECTED);
}
unlock_mount_hash();
put_mountpoint(mp);