fs: umount on symlink leaks mnt count
authorVasily Averin <vvs@parallels.com>
Mon, 21 Jul 2014 08:30:23 +0000 (12:30 +0400)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 31 Jul 2014 19:52:56 +0000 (12:52 -0700)
commit9b32e18d7ba2838991794893f10bf48805ef01ce
tree98119130cf53d9dcadbc85518959b07aebc8c44a
parent5b5897f0c11132a9b42ffbee8f93c71ab9504300
fs: umount on symlink leaks mnt count

commit 295dc39d941dc2ae53d5c170365af4c9d5c16212 upstream.

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>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs/namei.c