From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id AAC3DC43334 for ; Thu, 2 Jun 2022 12:38:37 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F3FA36B0071; Thu, 2 Jun 2022 08:38:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EEEF26B0072; Thu, 2 Jun 2022 08:38:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DB44F6B0073; Thu, 2 Jun 2022 08:38:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id CBAB26B0071 for ; Thu, 2 Jun 2022 08:38:36 -0400 (EDT) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 99FD134FD8 for ; Thu, 2 Jun 2022 12:38:36 +0000 (UTC) X-FDA: 79533249432.12.2FAAC9C Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf20.hostedemail.com (Postfix) with ESMTP id 5E93F1C0061 for ; Thu, 2 Jun 2022 12:38:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=s5OuhuXYOeyE5UF5dmXoLvghk44rQZnLPb2h1/XcCPg=; b=CLdDZpnXhsBm2c9XM9B5FToU/M LyNk4DIYVj1phFej49cZkTUIX9N0diwt44Ff6V3AAWidHxpiqQOieGX/Yo6Zz60us5Gm931KmiSnQ xkOiHmp8M23pbLA5AjuvsK0k5SeUjKvY66a1zkj2BtuV9XT/3N6o97VijmXSCUw00txBRgKdzN2Zq fdQJuAkoUTA4KZXnhfn9pdiiN0SmNKPjY9p1rRLfyAMGRbHtU7otoJwe9lt9jMhs91gJRaD6RTF3T F16+aSgbAIAjhd9MEQ6hjBeC1a/wN2fwO3WvSegDJebimWMhSNwN9Pite5GoHG1gEEx8SxS0sTFAK 88Qw4STA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nwk5q-0078sD-1n; Thu, 02 Jun 2022 12:38:26 +0000 Date: Thu, 2 Jun 2022 13:38:26 +0100 From: Matthew Wilcox To: Stefan Roesch Cc: io-uring@vger.kernel.org, kernel-team@fb.com, linux-mm@kvack.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, david@fromorbit.com, jack@suse.cz, hch@infradead.org, axboe@kernel.dk Subject: Re: [PATCH v7 06/15] iomap: Return error code from iomap_write_iter() Message-ID: References: <20220601210141.3773402-1-shr@fb.com> <20220601210141.3773402-7-shr@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220601210141.3773402-7-shr@fb.com> X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 5E93F1C0061 X-Stat-Signature: zatmmcaf7o4uy3zbtde4izjsz9p3uaqm Authentication-Results: imf20.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=CLdDZpnX; dmarc=none; spf=none (imf20.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-HE-Tag: 1654173496-616568 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Jun 01, 2022 at 02:01:32PM -0700, Stefan Roesch wrote: > Change the signature of iomap_write_iter() to return an error code. In > case we cannot allocate a page in iomap_write_begin(), we will not retry > the memory alloction in iomap_write_begin(). loff_t can already represent an error code. And it's already used like that. > @@ -829,7 +830,8 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) > length -= status; > } while (iov_iter_count(i) && length); > > - return written ? written : status; > + *processed = written ? written : error; > + return error; I think the change you really want is: if (status == -EAGAIN) return -EAGAIN; if (written) return written; return status; > @@ -843,12 +845,15 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i, > .flags = IOMAP_WRITE, > }; > int ret; > + int error = 0; > > if (iocb->ki_flags & IOCB_NOWAIT) > iter.flags |= IOMAP_NOWAIT; > > - while ((ret = iomap_iter(&iter, ops)) > 0) > - iter.processed = iomap_write_iter(&iter, i); > + while ((ret = iomap_iter(&iter, ops)) > 0) { > + if (error != -EAGAIN) > + error = iomap_write_iter(&iter, i, &iter.processed); > + } You don't need to change any of this. Look at how iomap_iter_advance() works.