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fs: umount on symlink leaks mnt count

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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>
Acked-by: Ian Kent <raven@themaw.net>
Acked-by: Jeff Layton <jlayton@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Vasily Averin 2014-07-21 12:30:23 +04:00 committed by Christoph Hellwig
parent 6fcc5420bf
commit 295dc39d94
1 changed files with 2 additions and 1 deletions
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3
fs/namei.c
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@ -2256,9 +2256,10 @@ mountpoint_last(struct nameidata *nd, struct path *path)
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: