mnt: Factor umount_mnt from umount_tree

For future use factor out a function umount_mnt from umount_tree.
This function unhashes a mount and remembers where the mount
was mounted so that eventually when the code makes it to a
sleeping context the mountpoint can be dput.

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 e669a3b..010d5be 100644 (file)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -822,6 +822,16 @@ static void detach_mnt(struct mount *mnt, struct path *old_path)
 /*
  * vfsmount lock must be held for write
  */
+static void umount_mnt(struct mount *mnt)
+{
+       /* old mountpoint will be dropped when we can do that */
+       mnt->mnt_ex_mountpoint = mnt->mnt_mountpoint;
+       unhash_mnt(mnt);
+}
+
+/*
+ * vfsmount lock must be held for write
+ */
 void mnt_set_mountpoint(struct mount *mnt,
                        struct mountpoint *mp,
                        struct mount *child_mnt)
@@ -1371,9 +1381,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
                pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, &unmounted);
                if (mnt_has_parent(p)) {
                        mnt_add_count(p->mnt_parent, -1);
-                       /* old mountpoint will be dropped when we can do that */
-                       p->mnt_ex_mountpoint = p->mnt_mountpoint;
-                       unhash_mnt(p);
+                       umount_mnt(p);
                }
                change_mnt_propagation(p, MS_PRIVATE);
        }