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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29001C43603 for ; Fri, 13 Dec 2019 00:58:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EBE4221655 for ; Fri, 13 Dec 2019 00:58:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="RHWYJIwi" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727925AbfLMA6B (ORCPT ); Thu, 12 Dec 2019 19:58:01 -0500 Received: from mail-pg1-f193.google.com ([209.85.215.193]:40048 "EHLO mail-pg1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727835AbfLMA6B (ORCPT ); Thu, 12 Dec 2019 19:58:01 -0500 Received: by mail-pg1-f193.google.com with SMTP id k25so635187pgt.7 for ; Thu, 12 Dec 2019 16:58:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:from:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=kPUFVfOVAnF2JsF7KBCO7Zshd0dUdc7irjBRYIOyMZw=; b=RHWYJIwiPf++l18S8H7nWplShVpnXgchNP7T5uXsv+euP1AKizc+7XgoWD7elMIoS9 +93QAEGvIaI8iMgqA5Gi3HC2r6igfHIKSLcDpXjBRu2EKbxCKRO5QWkrbDBuvO594/zG tao4apYk+as3E6xLeWwLnOjRNw+1XWdwshMpSLvUx6kQbuRlNAkqddKeuQLvFTkdHbC0 b/tDe5unV7I0ILNCJncr3xB7Lkji0cuT9+DQgcuhk2fxyzBt7Ki8z/2j5f2OKv1HYpPP SaLVNlvx35mgy0Ey5+NBAzwPElpJdVv78v7xqO8pX5pVs1x6lBUQouOh5rwd8ASrfVIu R3PQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=kPUFVfOVAnF2JsF7KBCO7Zshd0dUdc7irjBRYIOyMZw=; b=JRIvFPBvlTqQG1ibJkOsjnQhiUdbsDQhLtlmd6h4VBjFccIAPv/1tQjiAlE06utK2l oFiW5NYArcPZzjiD9J+hwPX4l6csy/sI3h1s6QtUWl/GkFqIntuE1WKNR2WJ5WoQcOPX fTp9RdJuM5A5c5WJu+LNsgfsK31yJIrhUlAQw9pQyFLsnMKSZEnsL70n/n2astwXbUEP Jl6SZ4KqeySuuqdD/g3XEsMrkt5xuk6lWxfxbJXPxHFsUwiD45IhLz7sY6d2oW/nVboI 1tbxa5rBScOoFwhX49yKMr0LsFqC//x2RAxbxa81Y29OW5RdrjvGFRww1nXrezhsWBew g1cQ== X-Gm-Message-State: APjAAAVfI8zd6Ce0Z/vHo3Ov8dGbv71GPrRPgWF2P2I16kBkJyhhdBjv nHQL4vWEFkrwEZzbO/iKG6g0VQ== X-Google-Smtp-Source: APXvYqyoESWHbhxbNpM9sP+Mvi0gku5Yus79Kx17lJ6LugtKZUcRGJHakDcIWfC5uCf7M+sQk4FyIw== X-Received: by 2002:a62:ac03:: with SMTP id v3mr12949073pfe.17.1576198680455; Thu, 12 Dec 2019 16:58:00 -0800 (PST) Received: from [192.168.1.188] ([66.219.217.145]) by smtp.gmail.com with ESMTPSA id 133sm8538744pfy.14.2019.12.12.16.57.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Dec 2019 16:57:59 -0800 (PST) Subject: Re: [PATCH 5/5] iomap: support RWF_UNCACHED for buffered writes From: Jens Axboe To: Dave Chinner Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, willy@infradead.org, clm@fb.com, torvalds@linux-foundation.org References: <20191211152943.2933-1-axboe@kernel.dk> <20191211152943.2933-6-axboe@kernel.dk> <20191212223403.GH19213@dread.disaster.area> Message-ID: <39af5a4d-7539-5746-ac3e-e2d6bd2209e3@kernel.dk> Date: Thu, 12 Dec 2019 17:57:57 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 12/12/19 5:54 PM, Jens Axboe wrote: > On 12/12/19 3:34 PM, Dave Chinner wrote: >> On Wed, Dec 11, 2019 at 08:29:43AM -0700, Jens Axboe wrote: >>> This adds support for RWF_UNCACHED for file systems using iomap to >>> perform buffered writes. We use the generic infrastructure for this, >>> by tracking pages we created and calling write_drop_cached_pages() >>> to issue writeback and prune those pages. >>> >>> Signed-off-by: Jens Axboe >>> --- >>> fs/iomap/apply.c | 24 ++++++++++++++++++++++++ >>> fs/iomap/buffered-io.c | 37 +++++++++++++++++++++++++++++-------- >>> include/linux/iomap.h | 5 +++++ >>> 3 files changed, 58 insertions(+), 8 deletions(-) >>> >>> diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c >>> index 562536da8a13..966826ad4bb9 100644 >>> --- a/fs/iomap/apply.c >>> +++ b/fs/iomap/apply.c >>> @@ -90,5 +90,29 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags, >>> flags, &iomap); >>> } >>> >>> + if (written && (flags & IOMAP_UNCACHED)) { >>> + struct address_space *mapping = inode->i_mapping; >>> + >>> + end = pos + written; >>> + ret = filemap_write_and_wait_range(mapping, pos, end); >>> + if (ret) >>> + goto out; >>> + >>> + /* >>> + * No pages were created for this range, we're done >>> + */ >>> + if (!(iomap.flags & IOMAP_F_PAGE_CREATE)) >>> + goto out; >>> + >>> + /* >>> + * Try to invalidate cache pages for the range we just wrote. >>> + * We don't care if invalidation fails as the write has still >>> + * worked and leaving clean uptodate pages in the page cache >>> + * isn't a corruption vector for uncached IO. >>> + */ >>> + invalidate_inode_pages2_range(mapping, >>> + pos >> PAGE_SHIFT, end >> PAGE_SHIFT); >>> + } >>> +out: >>> return written ? written : ret; >>> } >> >> Just a thought on further optimisation for this for XFS. >> IOMAP_UNCACHED is being passed into the filesystem ->iomap_begin >> methods by iomap_apply(). Hence the filesystems know that it is >> an uncached IO that is being done, and we can tailor allocation >> strategies to suit the fact that the data is going to be written >> immediately. >> >> In this case, XFS needs to treat it the same way it treats direct >> IO. That is, we do immediate unwritten extent allocation rather than >> delayed allocation. This will reduce the allocation overhead and >> will optimise for immediate IO locality rather than optimise for >> delayed allocation. >> >> This should just be a relatively simple change to >> xfs_file_iomap_begin() along the lines of: >> >> - if ((flags & (IOMAP_WRITE | IOMAP_ZERO)) && !(flags & IOMAP_DIRECT) && >> - !IS_DAX(inode) && !xfs_get_extsz_hint(ip)) { >> + if ((flags & (IOMAP_WRITE | IOMAP_ZERO)) && >> + !(flags & (IOMAP_DIRECT | IOMAP_UNCACHED)) && >> + !IS_DAX(inode) && !xfs_get_extsz_hint(ip)) { >> /* Reserve delalloc blocks for regular writeback. */ >> return xfs_file_iomap_begin_delay(inode, offset, length, flags, >> iomap); >> } >> >> so that it avoids delayed allocation for uncached IO... > > That's very handy! Thanks, I'll add that to the next version. Just out > of curiosity, would you prefer this as a separate patch, or just bundle > it with the iomap buffered RWF_UNCACHED patch? I'm assuming the latter, > and I'll just mention it in the changelog. OK, since it's in XFS, it'd be a separate patch. The code you quote seems to be something out-of-tree? -- Jens Axboe