Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751000AbWLLKSv (ORCPT ); Tue, 12 Dec 2006 05:18:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751104AbWLLKSv (ORCPT ); Tue, 12 Dec 2006 05:18:51 -0500 Received: from mailhub.sw.ru ([195.214.233.200]:20456 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751000AbWLLKSv (ORCPT ); Tue, 12 Dec 2006 05:18:51 -0500 To: Andrew Morton Cc: Dmitriy Monakhov , Dmitriy Monakhov , linux-kernel@vger.kernel.org, Linux Memory Management , , xfs@oss.sgi.com Subject: Re: [PATCH] incorrect error handling inside generic_file_direct_write References: <87k60y1rq4.fsf@sw.ru> <20061211124052.144e69a0.akpm@osdl.org> <87bqm9tie3.fsf@sw.ru> <20061212015232.eacfbb46.akpm@osdl.org> From: Dmitriy Monakhov Date: Tue, 12 Dec 2006 16:18:32 +0300 In-Reply-To: <20061212015232.eacfbb46.akpm@osdl.org> (Andrew Morton's message of "Tue, 12 Dec 2006 01:52:32 -0800") Message-ID: <87psapz1zr.fsf@sw.ru> User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="=-=-=" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2366 Lines: 68 --=-=-= Andrew Morton writes: > On Tue, 12 Dec 2006 15:20:52 +0300 > Dmitriy Monakhov wrote: > >> > XFS (at least) can call generic_file_direct_write() with i_mutex not held. >> > And vmtruncate() expects i_mutex to be held. >> > >> > I guess a suitable solution would be to push this problem back up to the >> > callers: let them decide whether to run vmtruncate() and if so, to ensure >> > that i_mutex is held. >> > >> > The existence of generic_file_aio_write_nolock() makes that rather messy >> > though. >> This means we may call generic_file_aio_write_nolock() without i_mutex, right? >> but call trace is : >> generic_file_aio_write_nolock() >> ->generic_file_buffered_write() /* i_mutex not held here */ >> but according to filemaps locking rules: mm/filemap.c:77 >> .. >> * ->i_mutex (generic_file_buffered_write) >> * ->mmap_sem (fault_in_pages_readable->do_page_fault) >> .. >> I'm confused a litle bit, where is the truth? > > xfs_write() calls generic_file_direct_write() without taking i_mutex for > O_DIRECT writes. Yes, but my quastion is about __generic_file_aio_write_nolock(). As i understand _nolock sufix means that i_mutex was already locked by caller, am i right ? If yes, than __generic_file_aio_write_nolock() is beter place for vmtrancate() acclivity after generic_file_direct_write() has fail. Signed-off-by: Dmitriy Monakhov ------- --=-=-= Content-Disposition: inline; filename=diff-generic-direct-io-write-fix diff --git a/mm/filemap.c b/mm/filemap.c index 7b84dc8..723d2ca 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2282,6 +2282,15 @@ __generic_file_aio_write_nolock(struct k written = generic_file_direct_write(iocb, iov, &nr_segs, pos, ppos, count, ocount); + if (written < 0) { + loff_t isize = i_size_read(inode); + /* + * generic_file_direct_write() may have instantiated + * a few blocks outside i_size. Trim these off again. + */ + if (pos + count > isize) + vmtruncate(inode, isize); + } if (written < 0 || written == count) goto out; /* --=-=-=-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/