From patchwork Thu May 26 17:38:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Roesch X-Patchwork-Id: 12862610 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 507CCC4332F for ; Thu, 26 May 2022 17:39:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348380AbiEZRj0 (ORCPT ); Thu, 26 May 2022 13:39:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348318AbiEZRjK (ORCPT ); Thu, 26 May 2022 13:39:10 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 54C75994FE for ; Thu, 26 May 2022 10:39:09 -0700 (PDT) Received: from pps.filterd (m0109333.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 24QFmfwP025621 for ; Thu, 26 May 2022 10:39:09 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=ntJvO4MQhogPOoilzqoG3I60GXy7qXbkAEj7dOQp0G0=; b=Uo9rwFWxx74vwoGm589BbGSUgPnbumsx7jaoN3fiqMte3Cj9NVoR1EHVHdrUDEXyAvFs tO3WpjrKDcAfsVDJwmwp1JJefwI28o1TmP67Kz7CCoIh2W6WOx1KDO74CrAi+aIm2k58 52Tp0+iv/qKdMNjXzNqZr1CczUoJKIAw+vI= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3gacgx8tk4-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 26 May 2022 10:39:09 -0700 Received: from twshared4937.07.ash9.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:21d::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Thu, 26 May 2022 10:39:07 -0700 Received: by devvm225.atn0.facebook.com (Postfix, from userid 425415) id 7AE70FA621D6; Thu, 26 May 2022 10:38:45 -0700 (PDT) From: Stefan Roesch To: , , , , CC: , , , Subject: [PATCH v6 05/16] iomap: Add async buffered write support Date: Thu, 26 May 2022 10:38:29 -0700 Message-ID: <20220526173840.578265-6-shr@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220526173840.578265-1-shr@fb.com> References: <20220526173840.578265-1-shr@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: xJ0OXb5-pCGQMlcsRszZVD8-orDiY4af X-Proofpoint-ORIG-GUID: xJ0OXb5-pCGQMlcsRszZVD8-orDiY4af X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.486,FMLib:17.11.64.514 definitions=2022-05-26_09,2022-05-25_02,2022-02-23_01 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org This adds async buffered write support to iomap. This replaces the call to balance_dirty_pages_ratelimited() with the call to balance_dirty_pages_ratelimited_flags. This allows to specify if the write request is async or not. In addition this also moves the above function call to the beginning of the function. If the function call is at the end of the function and the decision is made to throttle writes, then there is no request that io-uring can wait on. By moving it to the beginning of the function, the write request is not issued, but returns -EAGAIN instead. io-uring will punt the request and process it in the io-worker. By moving the function call to the beginning of the function, the write throttling will happen one page later. Signed-off-by: Stefan Roesch Reviewed-by: Jan Kara Reviewed-by: Christoph Hellwig --- fs/iomap/buffered-io.c | 31 +++++++++++++++++++++++++++---- 1 file changed, 27 insertions(+), 4 deletions(-) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index d6ddc54e190e..2281667646d2 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -559,6 +559,7 @@ static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos, loff_t block_size = i_blocksize(iter->inode); loff_t block_start = round_down(pos, block_size); loff_t block_end = round_up(pos + len, block_size); + unsigned int nr_blocks = i_blocks_per_folio(iter->inode, folio); size_t from = offset_in_folio(folio, pos), to = from + len; size_t poff, plen; @@ -567,6 +568,8 @@ static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos, folio_clear_error(folio); iop = iomap_page_create(iter->inode, folio, iter->flags); + if ((iter->flags & IOMAP_NOWAIT) && !iop && nr_blocks > 1) + return -EAGAIN; do { iomap_adjust_read_range(iter->inode, folio, &block_start, @@ -584,7 +587,12 @@ static int __iomap_write_begin(const struct iomap_iter *iter, loff_t pos, return -EIO; folio_zero_segments(folio, poff, from, to, poff + plen); } else { - int status = iomap_read_folio_sync(block_start, folio, + int status; + + if (iter->flags & IOMAP_NOWAIT) + return -EAGAIN; + + status = iomap_read_folio_sync(block_start, folio, poff, plen, srcmap); if (status) return status; @@ -613,6 +621,9 @@ static int iomap_write_begin(const struct iomap_iter *iter, loff_t pos, unsigned fgp = FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE | FGP_NOFS; int status = 0; + if (iter->flags & IOMAP_NOWAIT) + fgp |= FGP_NOWAIT; + BUG_ON(pos + len > iter->iomap.offset + iter->iomap.length); if (srcmap != &iter->iomap) BUG_ON(pos + len > srcmap->offset + srcmap->length); @@ -750,6 +761,8 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) loff_t pos = iter->pos; ssize_t written = 0; long status = 0; + struct address_space *mapping = iter->inode->i_mapping; + unsigned int bdp_flags = (iter->flags & IOMAP_NOWAIT) ? BDP_ASYNC : 0; do { struct folio *folio; @@ -762,6 +775,11 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) bytes = min_t(unsigned long, PAGE_SIZE - offset, iov_iter_count(i)); again: + status = balance_dirty_pages_ratelimited_flags(mapping, + bdp_flags); + if (unlikely(status)) + break; + if (bytes > length) bytes = length; @@ -770,6 +788,10 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) * Otherwise there's a nasty deadlock on copying from the * same page as we're writing to, without it being marked * up-to-date. + * + * For async buffered writes the assumption is that the user + * page has already been faulted in. This can be optimized by + * faulting the user page in the prepare phase of io-uring. */ if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) { status = -EFAULT; @@ -781,7 +803,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) break; page = folio_file_page(folio, pos >> PAGE_SHIFT); - if (mapping_writably_mapped(iter->inode->i_mapping)) + if (mapping_writably_mapped(mapping)) flush_dcache_page(page); copied = copy_page_from_iter_atomic(page, offset, bytes, i); @@ -806,8 +828,6 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) pos += status; written += status; length -= status; - - balance_dirty_pages_ratelimited(iter->inode->i_mapping); } while (iov_iter_count(i) && length); return written ? written : status; @@ -825,6 +845,9 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *i, }; int ret; + if (iocb->ki_flags & IOCB_NOWAIT) + iter.flags |= IOMAP_NOWAIT; + while ((ret = iomap_iter(&iter, ops)) > 0) iter.processed = iomap_write_iter(&iter, i); if (iter.pos == iocb->ki_pos)