linux-kernel - [patch v2] fs: umount on symlinlk leaks mnt count

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Message-ID: <53CB708B.7010508@parallels.com>
Date:	Sun, 20 Jul 2014 11:32:27 +0400
From:	Vasily Averin <vvs@...allels.com>
To:	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [patch v2] fs: umount on symlinlk leaks mnt count

v2: mntget(path->mnt) should not be called if mountpoint_last() returns 1.

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@...nvz.org>


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