From: Yan, Zheng <zheng.z.yan@intel.com>
Date: Tue, 2 Jul 2013 04:40:19 +0000 (+0800)
Subject: ceph: fix pending vmtruncate race
X-Git-Tag: v3.11-rc1~69^2~4
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b415bf4f9fe25f39934f5c464125e4a2dffb6d08;p=pandora-kernel.git

ceph: fix pending vmtruncate race

The locking order for pending vmtruncate is wrong, it can lead to
following race:

        write                  wmtruncate work
------------------------    ----------------------
lock i_mutex
check i_truncate_pending   check i_truncate_pending
truncate_inode_pages()     lock i_mutex (blocked)
copy data to page cache
unlock i_mutex
                           truncate_inode_pages()

The fix is take i_mutex before calling __ceph_do_pending_vmtruncate()

Fixes: http://tracker.ceph.com/issues/5453
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Sage Weil <sage@inktank.com>
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