From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f66.google.com ([209.85.214.66]:40172 "EHLO mail-it0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S969458AbeEXUxq (ORCPT ); Thu, 24 May 2018 16:53:46 -0400 Received: by mail-it0-f66.google.com with SMTP id j186-v6so4177544ita.5 for ; Thu, 24 May 2018 13:53:46 -0700 (PDT) Subject: Re: [PATCH 3/3] ext4: readpages() should submit IO as read-ahead To: "Theodore Y. Ts'o" Cc: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org References: <1527177774-21414-1-git-send-email-axboe@kernel.dk> <1527177774-21414-4-git-send-email-axboe@kernel.dk> <20180524204730.GC7712@thunk.org> From: Jens Axboe Message-ID: Date: Thu, 24 May 2018 14:53:43 -0600 MIME-Version: 1.0 In-Reply-To: <20180524204730.GC7712@thunk.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On 5/24/18 2:47 PM, Theodore Y. Ts'o wrote: > On Thu, May 24, 2018 at 10:02:54AM -0600, Jens Axboe wrote: >> a_ops->readpages() is only ever used for read-ahead. Ensure that we >> pass this information down to the block layer. >> >> Signed-off-by: Jens Axboe >> --- >> fs/ext4/readpage.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c >> index 9ffa6fad18db..92b28273b223 100644 >> --- a/fs/ext4/readpage.c >> +++ b/fs/ext4/readpage.c >> @@ -259,7 +259,7 @@ int ext4_mpage_readpages(struct address_space *mapping, >> bio->bi_iter.bi_sector = blocks[0] << (blkbits - 9); >> bio->bi_end_io = mpage_end_io; >> bio->bi_private = ctx; >> - bio_set_op_attrs(bio, REQ_OP_READ, 0); >> + bio_set_op_attrs(bio, REQ_OP_READ, REQ_RAHEAD); >> } > > The problem is that ext4_readpage() also calls ext4_mpage_readpages(). > So you can't set REQ_RAHEAD unconditionally here. Oh shoot, yeah I did miss that. I'll update it, thanks Ted. -- Jens Axboe