From: jiangyiwen <jiangyiwen@huawei.com>
Date: Thu, 3 Apr 2014 21:47:13 +0000 (-0700)
Subject: ocfs2: avoid system inode ref confusion by adding mutex lock
X-Git-Tag: v3.15-rc1~106^2~188
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=43b10a20372d9a1c08391f33f1c8bd86179ddc5f;p=pandora-kernel.git

ocfs2: avoid system inode ref confusion by adding mutex lock

The following case may lead to the same system inode ref in confusion.

A thread                            B thread
ocfs2_get_system_file_inode
->get_local_system_inode
->_ocfs2_get_system_file_inode
                                    because of *arr == NULL,
                                    ocfs2_get_system_file_inode
                                    ->get_local_system_inode
                                    ->_ocfs2_get_system_file_inode
gets first ref thru
_ocfs2_get_system_file_inode,
gets second ref thru igrab and
set *arr = inode
                                    at the moment, B thread also gets
                                    two refs, so lead to one more
                                    inode ref.

So add mutex lock to avoid multi thread set two inode ref once at the
same time.

Signed-off-by: jiangyiwen <jiangyiwen@huawei.com>
Reviewed-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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