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authorMiklos Szeredi <miklos@szeredi.hu>2005-08-07 20:42:25 +0400
committerLinus Torvalds <torvalds@g5.osdl.org>2005-08-07 21:00:38 +0400
commit68b47139ea94ab6d05e89c654db8daa99e9a232c (patch)
tree807d693b22a11f7667cd16e90b43618f85f8a4e0
parent9ae5b3c703cce89a7d8ccf25fe16955ec6f016c0 (diff)
downloadlinux-68b47139ea94ab6d05e89c654db8daa99e9a232c.tar.xz
[PATCH] namespace.c: fix bind mount from foreign namespace
I'm resending this patch, because I still believe it's the correct fix. Tested before/after applying the patch with a test application available from: http://www.inf.bme.hu/~mszeredi/nstest.c 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 in clone_mnt(). 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. Jamie said: This patch is correct. The old code was buggy for more fundamental and serious reason: it broke the invariant that a tree of vfsmnts all have the same value of mnt_namespace (and the same for the mnt_list list). Signed-off-by: Miklos Szeredi <miklos@szeredi.hu> Acked-by: Jamie Lokier <jamie@shareable.org> Cc: <viro@parcelfarce.linux.theplanet.co.uk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--fs/namespace.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 587eb0d707ee..79bd8a46e1e7 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -160,7 +160,7 @@ clone_mnt(struct vfsmount *old, struct dentry *root)
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 */