From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756557Ab0E2MK0 (ORCPT ); Sat, 29 May 2010 08:10:26 -0400 Received: from mail.skyhub.de ([78.46.96.112]:57610 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756254Ab0E2MKZ (ORCPT ); Sat, 29 May 2010 08:10:25 -0400 Date: Sat, 29 May 2010 14:10:19 +0200 From: Borislav Petkov To: Changli Gao Cc: Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] fs: optimize mpage_readpage() Message-ID: <20100529121019.GA25092@liondog.tnic> Mail-Followup-To: Borislav Petkov , Changli Gao , Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <1275095926-18345-1-git-send-email-xiaosuo@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1275095926-18345-1-git-send-email-xiaosuo@gmail.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Changli Gao Date: Sat, May 29, 2010 at 09:18:46AM +0800 > optimize mpage_readpage() > > we don't need to initialize bio, and pass it to do_mpage_readpage() as > parameter, as it is returned by do_mpage_readpage(). > > Signed-off-by: Changli Gao > ---- > fs/mpage.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > diff --git a/fs/mpage.c b/fs/mpage.c > index fd56ca2..94ff0d1 100644 > --- a/fs/mpage.c > +++ b/fs/mpage.c > @@ -409,14 +409,14 @@ EXPORT_SYMBOL(mpage_readpages); > */ > int mpage_readpage(struct page *page, get_block_t get_block) > { > - struct bio *bio = NULL; > + struct bio *bio; > sector_t last_block_in_bio = 0; > struct buffer_head map_bh; > unsigned long first_logical_block = 0; > > map_bh.b_state = 0; > map_bh.b_size = 0; > - bio = do_mpage_readpage(bio, page, 1, &last_block_in_bio, > + bio = do_mpage_readpage(NULL, page, 1, &last_block_in_bio, > &map_bh, &first_logical_block, get_block); > if (bio) > mpage_bio_submit(READ, bio); Nope, I don't think that's a good idea. On the one hand, this is a trick to shut up gcc: fs/mpage.c: In function ‘mpage_readpage’: fs/mpage.c:419: warning: ‘bio’ is used uninitialized in this function and, on the other hand, make sure bio is NULL and not some random stack value since bio is explicitly checked for NULL in do_mpage_readpage(). -- Regards/Gruss, Boris.