From patchwork Wed Jun 1 21:01:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Roesch X-Patchwork-Id: 12867264 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 0A3A2C433EF for ; Wed, 1 Jun 2022 21:04:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230516AbiFAVE2 (ORCPT ); Wed, 1 Jun 2022 17:04:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38622 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230359AbiFAVEU (ORCPT ); Wed, 1 Jun 2022 17:04:20 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2BD7822FE4A for ; Wed, 1 Jun 2022 14:04:17 -0700 (PDT) Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 251K3k6n028658 for ; Wed, 1 Jun 2022 14:04:16 -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=SanAPp/GdGsVkoF9K0kGfp+PZp6DCWAFgZk5IqjhpxA=; b=QXfb/uVVLSkuKSxIuj2dp3p4MlMpnI8918rFKtavGeCf7sgj8TSJoeOqI5DB7ZnbeU7t Uq2N7rpskf1XrL6bySj3iLwDXYLNBpZ3Nk99DIq8peeoZQZMCilp9jDysGjQFX0MDMS0 Qhea9zc1mGjVgr0Zf09rSU+X0nx3iq9XBsg= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3gdt5jqfy8-4 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 01 Jun 2022 14:04:16 -0700 Received: from twshared10560.18.frc3.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Wed, 1 Jun 2022 14:04:13 -0700 Received: by devvm225.atn0.facebook.com (Postfix, from userid 425415) id CF9ABFEB239D; Wed, 1 Jun 2022 14:01:42 -0700 (PDT) From: Stefan Roesch To: , , , , CC: , , , , , Christoph Hellwig Subject: [PATCH v7 05/15] iomap: Add async buffered write support Date: Wed, 1 Jun 2022 14:01:31 -0700 Message-ID: <20220601210141.3773402-6-shr@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220601210141.3773402-1-shr@fb.com> References: <20220601210141.3773402-1-shr@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: QMWCiAViY1Jt-rksEnQqFoaUXAIHBpMx X-Proofpoint-ORIG-GUID: QMWCiAViY1Jt-rksEnQqFoaUXAIHBpMx X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.874,Hydra:6.0.517,FMLib:17.11.64.514 definitions=2022-06-01_08,2022-06-01_01,2022-02-23_01 Precedence: bulk List-ID: X-Mailing-List: io-uring@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 | 33 ++++++++++++++++++++++++++++----- 1 file changed, 28 insertions(+), 5 deletions(-) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 705f80cd2d4e..b06a5c24a4db 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -558,6 +558,7 @@ 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; @@ -566,6 +567,8 @@ 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, @@ -583,7 +586,12 @@ 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; @@ -612,6 +620,9 @@ 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); @@ -631,7 +642,7 @@ static int iomap_write_begin(const struct iomap_iter *iter, loff_t pos, folio = __filemap_get_folio(iter->inode->i_mapping, pos >> PAGE_SHIFT, fgp, mapping_gfp_mask(iter->inode->i_mapping)); if (!folio) { - status = -ENOMEM; + status = (iter->flags & IOMAP_NOWAIT) ? -EAGAIN : -ENOMEM; goto out_no_page; } if (pos + len > folio_pos(folio) + folio_size(folio)) @@ -749,6 +760,8 @@ 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; @@ -761,6 +774,11 @@ 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; @@ -769,6 +787,10 @@ 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. */ if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) { status = -EFAULT; @@ -780,7 +802,7 @@ 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); @@ -805,8 +827,6 @@ 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; @@ -824,6 +844,9 @@ 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)