From: Andrew Morton Subject: Re: [PATCH] Fix commit block write in JBD Date: Sat, 26 Jan 2008 22:02:07 -0800 Message-ID: <20080126220207.9152ff8b.akpm@linux-foundation.org> References: <20080123190943.GG10144@duck.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org To: Jan Kara Return-path: Received: from smtp2.linux-foundation.org ([207.189.120.14]:57248 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756776AbYA0GCp (ORCPT ); Sun, 27 Jan 2008 01:02:45 -0500 In-Reply-To: <20080123190943.GG10144@duck.suse.cz> Sender: linux-ext4-owner@vger.kernel.org List-ID: > On Wed, 23 Jan 2008 20:09:43 +0100 Jan Kara wrote: > > Commit block is expected to have several copies of the header. Fix the > bug Andrew has spotted ages ago. > "ages" indeed. > > diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c > index 610264b..a69b240 100644 > --- a/fs/jbd/commit.c > +++ b/fs/jbd/commit.c > @@ -116,9 +116,8 @@ static int journal_write_commit_record(journal_t *journal, > > bh = jh2bh(descriptor); > > - /* AKPM: buglet - add `i' to tmp! */ > for (i = 0; i < bh->b_size; i += 512) { > - journal_header_t *tmp = (journal_header_t*)bh->b_data; > + journal_header_t *tmp = (journal_header_t*)(bh->b_data+i); > tmp->h_magic = cpu_to_be32(JFS_MAGIC_NUMBER); > tmp->h_blocktype = cpu_to_be32(JFS_COMMIT_BLOCK); > tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid); But I don't think we can _use_ this feature now. Because there are 100000000000 disks out there which didn't implement it. So why not just remove the loop and do a single write?