fix deadlock in pivot_root()
authorAl Viro <viro@zeniv.linux.org.uk>
Fri, 18 Mar 2011 12:29:36 +0000 (08:29 -0400)
committerAl Viro <viro@zeniv.linux.org.uk>
Fri, 18 Mar 2011 12:54:59 +0000 (08:54 -0400)
commit27cb1572e3e6bb1f8cf6bb3d74c914a87b131792
tree01e6510de480d3595ccff315d777770490e51f9c
parent9d412a43c3b26e1e549319e5eec26f0829f9f74d
fix deadlock in pivot_root()

Don't hold vfsmount_lock over the loop traversing ->mnt_parent;
do check_mnt(new.mnt) under namespace_sem instead; combined with
namespace_sem held over all that code it'll guarantee the stability
of ->mnt_parent chain all the way to the root.

Doing check_mnt() outside of namespace_sem in case of pivot_root()
is wrong anyway.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
fs/namespace.c