Patch "mnt: Update detach_mounts to leave mounts connected" has been added to the 4.0-stable tree

Patch "mnt: Update detach_mounts to leave mounts connected" has been added to the 4.0-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    mnt: Update detach_mounts to leave mounts connected

to the 4.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mnt-update-detach_mounts-to-leave-mounts-connected.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From e0c9c0afd2fc958ffa34b697972721d81df8a56f Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Wed, 1 Apr 2015 18:30:06 -0500
Subject: mnt: Update detach_mounts to leave mounts connected

From: "Eric W. Biederman" <ebiederm@xmission.com>

commit e0c9c0afd2fc958ffa34b697972721d81df8a56f upstream.

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.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/namespace.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1350,6 +1350,7 @@ static inline void namespace_lock(void)
 enum umount_tree_flags {
 	UMOUNT_SYNC = 1,
 	UMOUNT_PROPAGATE = 2,
+	UMOUNT_CONNECTED = 4,
 };
 /*
  * mount_lock must be held
@@ -1388,7 +1389,10 @@ static void umount_tree(struct mount *mn
 		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);
@@ -1531,7 +1535,7 @@ void __detach_mounts(struct dentry *dent
 				umount_mnt(p);
 			}
 		}
-		else umount_tree(mnt, 0);
+		else umount_tree(mnt, UMOUNT_CONNECTED);
 	}
 	unlock_mount_hash();
 	put_mountpoint(mp);


Patches currently in stable-queue which might be from ebiederm@xmission.com are

queue-4.0/mnt-don-t-propagate-umounts-in-__detach_mounts.patch
queue-4.0/mnt-add-mnt_umount-flag.patch
queue-4.0/mnt-honor-mnt_locked-when-detaching-mounts.patch
queue-4.0/mnt-delay-removal-from-the-mount-hash.patch
queue-4.0/mnt-on-an-unmount-propagate-clearing-of-mnt_locked.patch
queue-4.0/mnt-don-t-propagate-unmounts-to-locked-mounts.patch
queue-4.0/mnt-factor-out-unhash_mnt-from-detach_mnt-and-umount_tree.patch
queue-4.0/mnt-factor-umount_mnt-from-umount_tree.patch
queue-4.0/mnt-fix-the-error-check-in-__detach_mounts.patch
queue-4.0/mnt-update-detach_mounts-to-leave-mounts-connected.patch
queue-4.0/mnt-improve-the-umount_tree-flags.patch
queue-4.0/mnt-in-umount_tree-reuse-mnt_list-instead-of-mnt_hash.patch