Patch "mnt: Factor out unhash_mnt from detach_mnt and umount_tree" has been added to the 4.0-stable tree

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

mnt: Factor out unhash_mnt from detach_mnt and umount_tree

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-factor-out-unhash_mnt-from-detach_mnt-and-umount_tree.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 <[email protected]> know about it.

From: "Eric W. Biederman" <[email protected]>
Date: Mon, 29 Dec 2014 13:03:41 -0600
Subject: mnt: Factor out unhash_mnt from detach_mnt and umount_tree

From: "Eric W. Biederman" <[email protected]>

commit 7bdb11de8ee4f4ae195e2fa19efd304e0b36c63b upstream.

Create a function unhash_mnt that contains the common code between detach_mnt and umount_tree, and use unhash_mnt in place of the common code. This add a unncessary list_del_init(mnt->mnt_child) into umount_tree but given that mnt_child is already empty this extra line is a noop.

---
 fs/namespace.c |   21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

@@ -798,10 +798,8 @@ static void __touch_mnt_namespace(struct
 /*
  * vfsmount lock must be held for write
  */
-static void detach_mnt(struct mount *mnt, struct path *old_path)
+static void unhash_mnt(struct mount *mnt)
 {
-	old_path->dentry = mnt->mnt_mountpoint;
-	old_path->mnt = &mnt->mnt_parent->mnt;
 	mnt->mnt_parent = mnt;
 	mnt->mnt_mountpoint = mnt->mnt.mnt_root;
 	list_del_init(&mnt->mnt_child);

@@ -814,6 +812,16 @@ static void detach_mnt(struct mount *mnt
 /*
  * vfsmount lock must be held for write
  */
+static void detach_mnt(struct mount *mnt, struct path *old_path)
+{
+	old_path->dentry = mnt->mnt_mountpoint;
+	old_path->mnt = &mnt->mnt_parent->mnt;
+	unhash_mnt(mnt);
+}
+
+/*
+ * vfsmount lock must be held for write
+ */
 void mnt_set_mountpoint(struct mount *mnt,
 			struct mountpoint *mp,
 			struct mount *child_mnt)

@@ -1364,15 +1372,10 @@ static void umount_tree(struct mount *mn
 
 		pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, &unmounted);
 		if (mnt_has_parent(p)) {
-			hlist_del_init(&p->mnt_mp_list);
-			put_mountpoint(p->mnt_mp);
 			mnt_add_count(p->mnt_parent, -1);
 			/* old mountpoint will be dropped when we can do that */
 			p->mnt_ex_mountpoint = p->mnt_mountpoint;
-			p->mnt_mountpoint = p->mnt.mnt_root;
-			p->mnt_parent = p;
-			p->mnt_mp = NULL;
-			hlist_del_init_rcu(&p->mnt_hash);
+			unhash_mnt(p);
 		}
 		change_mnt_propagation(p, MS_PRIVATE);
 	}

Patches currently in stable-queue which might be from [email protected] 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