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SubjectRe: [PATCH v4] fs: umount on symlink leaks mnt count
On Mon, 21 Jul 2014 12:30:23 +0400
Vasily Averin <vvs@parallels.com> wrote:

> v4: description corrected
> v3: patch inline
>
> Currently umount on symlink blocks following umount:
>
> /vz is separate mount
>
> # ls /vz/ -al | grep test
> drwxr-xr-x. 2 root root 4096 Jul 19 01:14 testdir
> lrwxrwxrwx. 1 root root 11 Jul 19 01:16 testlink -> /vz/testdir
> # umount -l /vz/testlink
> umount: /vz/testlink: not mounted (expected)
>
> # lsof /vz
> # umount /vz
> umount: /vz: device is busy. (unexpected)
>
> In this case mountpoint_last() gets an extra refcount on path->mnt
>
> Signed-off-by: Vasily Averin <vvs@openvz.org>
> ---
> fs/namei.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/fs/namei.c b/fs/namei.c
> index 985c6f3..9eb787e 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -2256,9 +2256,10 @@ done:
> goto out;
> }
> path->dentry = dentry;
> - path->mnt = mntget(nd->path.mnt);
> + path->mnt = nd->path.mnt;
> if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW))
> return 1;
> + mntget(path->mnt);
> follow_mount(path);
> error = 0;
> out:

Looks correct, I think...

Acked-by:
--
Jeff Layton <jlayton@primarydata.com>


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