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| author | Miklos Szeredi <miklos@szeredi.hu> | 2005-08-07 20:42:25 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-08-07 21:00:38 +0400 |
| commit | 68b47139ea94ab6d05e89c654db8daa99e9a232c (patch) | |
| tree | 807d693b22a11f7667cd16e90b43618f85f8a4e0 | |
| parent | 9ae5b3c703cce89a7d8ccf25fe16955ec6f016c0 (diff) | |
| download | linux-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.c | 2 |
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 */ |