From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from imap.thunk.org ([74.207.234.97]:51912 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966945AbeEXUrc (ORCPT ); Thu, 24 May 2018 16:47:32 -0400 Date: Thu, 24 May 2018 16:47:30 -0400 From: "Theodore Y. Ts'o" To: Jens Axboe Cc: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org Subject: Re: [PATCH 3/3] ext4: readpages() should submit IO as read-ahead Message-ID: <20180524204730.GC7712@thunk.org> References: <1527177774-21414-1-git-send-email-axboe@kernel.dk> <1527177774-21414-4-git-send-email-axboe@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1527177774-21414-4-git-send-email-axboe@kernel.dk> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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. - Ted