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Subject[PATCH] namespace.c: fix bind mount from foreign namespace
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Bind mount from a foreign namespace results in an un-removable mount.
The reason is that mnt->mnt_namespace is copied from the old mount in
clone_mnt(). Because of this, check_mnt() in sys_umount() will fail.

The solution is to set mnt->mnt_namespace to current->namespace.

clone_mnt() is either called from do_loopback() or copy_tree().
copy_tree() is called from do_loopback() or copy_namespace().

When called (directly or indirectly) from do_loopback(), always
current->namspace is being modified: check_mnt(nd->mnt). So setting
mnt->mnt_namespace to current->namspace is the right thing to do.

When called from copy_namespace(), the setting of mnt_namespace is
irrelevant, since mnt_namespace is reset later in that function for
all copied mounts.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>

Index: linux/fs/namespace.c
===================================================================
--- linux.orig/fs/namespace.c 2005-05-13 12:22:52.000000000 +0200
+++ linux/fs/namespace.c 2005-05-13 12:32:36.000000000 +0200
@@ -160,7 +160,7 @@ clone_mnt(struct vfsmount *old, struct d
mnt->mnt_root = dget(root);
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;
- mnt->mnt_namespace = old->mnt_namespace;
+ mnt->mnt_namespace = current->namespace;

/* stick the duplicate mount on the same expiry list
* as the original if that was on one */
-
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