From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Chinner Subject: Re: [git pull] vfs.git fixes for -rc2 Date: Mon, 10 Feb 2014 21:47:47 +1100 Message-ID: <20140210104747.GV13997@dastard> References: <20140209233643.GB18016@ZenIV.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Linus Torvalds , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org To: Al Viro Return-path: Content-Disposition: inline In-Reply-To: <20140209233643.GB18016@ZenIV.linux.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Sun, Feb 09, 2014 at 11:36:43PM +0000, Al Viro wrote: > A couple of fixes, both -stable fodder. O_SYNC bug is > fairly old... Please, pull from the usual place - > git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git for-linus > > Shortlog: > Al Viro (2): > fix O_SYNC|O_APPEND syncing the wrong range on write() As i pointed out in a private thread this doesn't fix XFS. It passes a private "pos" variable to generic_write_checks() and so iocb->ki_pos never gets updated to point at the new EOF when O_APPEND is set. Hence the code inthe above commit is still syncing the wrong range. Indeed, I think that __generic_file_aio_write has the same problem. It gets called from generic_file_aio_write() like so: ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); And __generic_file_aio_write() does this: pos = *ppos; .... err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode)); and the updated pos value on O_APPEND writes is never folded back into ppos. Hence the later call to generic_write_sync() still has the wrong range.... Cheers, Dave. -- Dave Chinner david@fromorbit.com