From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Date: Wed, 20 Apr 2011 10:08:47 +0000 (+0000)
Subject: Btrfs: drop unnecessary device lock
X-Git-Tag: v3.0-rc1~38^2~5^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=46224705656633466ca7dc71d81b3c0abc76cae4;p=pandora-kernel.git

Btrfs: drop unnecessary device lock

Drop device_list_mutex for the reader side  on clone_fs_devices and
btrfs_rm_device pathes since the fs_info->volume_mutex can ensure the device
list is not updated

btrfs_close_extra_devices is the initialized path, we can not add or remove
device at this time, so we can simply drop the mutex safely, like other
initialized function does(add_missing_dev, __find_device, __btrfs_open_devices
...).

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
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