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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72578C4167B for ; Fri, 23 Dec 2022 16:15:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230211AbiLWQPI (ORCPT ); Fri, 23 Dec 2022 11:15:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37764 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231279AbiLWQPG (ORCPT ); Fri, 23 Dec 2022 11:15:06 -0500 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76F5B3EAEF; Fri, 23 Dec 2022 08:15:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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=FOq+IQwreCAb5o5To4xtNwUVGrFfO+bGPhpkASaB1VQ=; b=ecOqksS/Qv7xqVgyuhb9U6fLLC mXCeg0KLXrUw9c3jhI8vITWaPjJc8jxilQlvNuI9QIJ2zEQrn2hEZELq/76mnzJ8LzouIaDlVGiv3 y5pFiChIOHF3ytLdNb5U29o/wYDLFJNAVI9DIAPtpsSzRajVSsX9Rve7Z4Gh6ko6t847Go83gzFdB 94dchHeXeM6EQTkX4569O15CFh+ICJOc6TatTkNURH4qXfDj7n12xYGGTYtU6JYzwCqhMdIgtJiJT SEGGO+QUHXcfDqkjBXT4rBWJgK27jPfLh5DyaHg6CxNPiLwHLQ8Zwa3zH0YCFw2Gu+fe53NuvpQ7e yHGfVvrw==; Received: from hch by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1p8khL-009riT-04; Fri, 23 Dec 2022 16:15:03 +0000 Date: Fri, 23 Dec 2022 08:15:02 -0800 From: Christoph Hellwig To: Dave Chinner Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, willy@infradead.org Subject: Re: [PATCH] [RFC] iomap: zeroing needs to be pagecache aware Message-ID: References: <20221201005214.3836105-1-david@fromorbit.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221201005214.3836105-1-david@fromorbit.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Dec 01, 2022 at 11:52:14AM +1100, Dave Chinner wrote: > folio = __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT, > fgp, mapping_gfp_mask(iter->inode->i_mapping)); > if (!folio) { > - status = (iter->flags & IOMAP_NOWAIT) ? -EAGAIN : -ENOMEM; > + if (!(fgp & FGP_CREAT)) > + status = -ENODATA; > + else if (iter->flags & IOMAP_NOWAIT) > + status = -EAGAIN; > + else > + status = -ENOMEM; Trying to reverse engineer the error case based on the flags passed seems a bit problematic, even if I think for now it mostl still works as !FGP_CREAT is exclusive vs IOMAP_NOWAIT. Matthew, what do you think of switching __filemap_get_folio to an ERR_PTR return and return actual cause? Or do we have too many callers and need ____filemap_get_folio (urrg..)? > + status = iomap_write_begin(iter, pos, bytes, &folio, fgp); > + if (status) { > + if (status == -ENODATA) { > + /* > + * No folio was found, so skip to the start of > + * the next potential entry in the page cache > + * and continue from there. > + */ > + if (bytes > PAGE_SIZE - offset_in_page(pos)) > + bytes = PAGE_SIZE - offset_in_page(pos); > + goto loop_continue; > + } > return status; > + } Nit: I'd check for -ENODATA one level of identation out to keep the nesting limited: status = iomap_write_begin(iter, pos, bytes, &folio, fgp); if (status == -ENODATA) { ... goto loop_continue; } if (status) return status;