From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Fri, 07 Sep 2007 05:15:20 -0700 (PDT) Received: from larry.melbourne.sgi.com (larry.melbourne.sgi.com [134.14.52.130]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with SMTP id l87CFF4p023224 for ; Fri, 7 Sep 2007 05:15:16 -0700 Date: Fri, 7 Sep 2007 22:15:05 +1000 From: David Chinner Subject: Re: Need of inode->i_mutex in xfs_write() Message-ID: <20070907121505.GX734179@sgi.com> References: <9ee2fe770708210826n5952e727od0df16a5a7b267f0@mail.gmail.com> <20070823225111.GW72985246@sgi.com> <9ee2fe770709062243u67956d26o7222435956213f0@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9ee2fe770709062243u67956d26o7222435956213f0@mail.gmail.com> Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: kanishk rastogi Cc: David Chinner , xfs@oss.sgi.com On Fri, Sep 07, 2007 at 11:28:27AM +0545, kanishk rastogi wrote: > On 8/24/07, David Chinner wrote: > > On Tue, Aug 21, 2007 at 09:11:56PM +0545, kanishk rastogi wrote: > > > I was looking at the xfs_write code path in kernel 2.6.20 ....... > > > I saw it acquiring inode->i_mutex . > > > Whats the need ? > > > What are we safegaurding inode for. > > > > See Documentation/filesystems/Locking and other files in that > > directory for what i_mutex is supposed to protect. > > > > XFS is different as it has it's own inodes and inode locks, but > > it still mostly uses i_mutex inteh accepted way. > > > > xfs_write comes in file_operations->aio_write() > and the documentation doesnt say anything for it to acquire i_mutex in > that path. The i_mutex is supposed to be held across various calls into generic code. See generic_file_aio_write() for the common implementation of ->aio_write(). The entire write path is supposed to be protected by the i_mutex. Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group