From patchwork Thu Apr 8 12:04:26 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shiyang Ruan X-Patchwork-Id: 12190859 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 9B30DC43470 for ; Thu, 8 Apr 2021 12:04:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7623E61159 for ; Thu, 8 Apr 2021 12:04:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231352AbhDHMEz (ORCPT ); Thu, 8 Apr 2021 08:04:55 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:24811 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S231195AbhDHMEy (ORCPT ); Thu, 8 Apr 2021 08:04:54 -0400 IronPort-HdrOrdr: A9a23:7G2dj6v6h/XP8m9i1FC+MU3j7skDltV00zAX/kB9WHVpW+afkN2jm+le6A/shF8qKRUdsP2jGI3Fe3PT8pZp/ZIcVI3OYCDKsHalRbsN0aLMzzHsECX19Kp8+M5bGZRWJ8b3CTFB7PrSxCmdP5IezMKc8Kau7N2uqktFaQ1xcalv40NYJ2+gYy5LbTJLD5Y4C5aQj/Avz1WdUE4KZce2DGRtZZmgm/T3kvvdASIuNloO7QmiqXeS4qfmLh7w5HwjegIK7bA80WWtqWDE2pk= X-IronPort-AV: E=Sophos;i="5.82,206,1613404800"; d="scan'208";a="106797244" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 08 Apr 2021 20:04:39 +0800 Received: from G08CNEXMBPEKD06.g08.fujitsu.local (unknown [10.167.33.206]) by cn.fujitsu.com (Postfix) with ESMTP id E5F494CF2676; Thu, 8 Apr 2021 20:04:36 +0800 (CST) Received: from G08CNEXJMPEKD02.g08.fujitsu.local (10.167.33.202) by G08CNEXMBPEKD06.g08.fujitsu.local (10.167.33.206) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 8 Apr 2021 20:04:36 +0800 Received: from G08CNEXCHPEKD04.g08.fujitsu.local (10.167.33.200) by G08CNEXJMPEKD02.g08.fujitsu.local (10.167.33.202) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 8 Apr 2021 20:04:36 +0800 Received: from irides.mr.mr.mr (10.167.225.141) by G08CNEXCHPEKD04.g08.fujitsu.local (10.167.33.209) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 8 Apr 2021 20:04:36 +0800 From: Shiyang Ruan To: , , , CC: , , , , , , , , Subject: [PATCH v4 1/7] fsdax: Introduce dax_iomap_cow_copy() Date: Thu, 8 Apr 2021 20:04:26 +0800 Message-ID: <20210408120432.1063608-2-ruansy.fnst@fujitsu.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20210408120432.1063608-1-ruansy.fnst@fujitsu.com> References: <20210408120432.1063608-1-ruansy.fnst@fujitsu.com> MIME-Version: 1.0 X-yoursite-MailScanner-ID: E5F494CF2676.A3511 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: ruansy.fnst@fujitsu.com Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org In the case where the iomap is a write operation and iomap is not equal to srcmap after iomap_begin, we consider it is a CoW operation. The destance extent which iomap indicated is new allocated extent. So, it is needed to copy the data from srcmap to new allocated extent. In theory, it is better to copy the head and tail ranges which is outside of the non-aligned area instead of copying the whole aligned range. But in dax page fault, it will always be an aligned range. So, we have to copy the whole range in this case. Signed-off-by: Shiyang Ruan Reviewed-by: Christoph Hellwig --- fs/dax.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 77 insertions(+), 5 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 8d7e4e2cc0fb..b4fd3813457a 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -1038,6 +1038,61 @@ static int dax_iomap_direct_access(struct iomap *iomap, loff_t pos, size_t size, return rc; } +/** + * dax_iomap_cow_copy(): Copy the data from source to destination before write. + * @pos: address to do copy from. + * @length: size of copy operation. + * @align_size: aligned w.r.t align_size (either PMD_SIZE or PAGE_SIZE) + * @srcmap: iomap srcmap + * @daddr: destination address to copy to. + * + * This can be called from two places. Either during DAX write fault, to copy + * the length size data to daddr. Or, while doing normal DAX write operation, + * dax_iomap_actor() might call this to do the copy of either start or end + * unaligned address. In this case the rest of the copy of aligned ranges is + * taken care by dax_iomap_actor() itself. + * Also, note DAX fault will always result in aligned pos and pos + length. + */ +static int dax_iomap_cow_copy(loff_t pos, loff_t length, size_t align_size, + struct iomap *srcmap, void *daddr) +{ + loff_t head_off = pos & (align_size - 1); + size_t size = ALIGN(head_off + length, align_size); + loff_t end = pos + length; + loff_t pg_end = round_up(end, align_size); + bool copy_all = head_off == 0 && end == pg_end; + void *saddr = 0; + int ret = 0; + + ret = dax_iomap_direct_access(srcmap, pos, size, &saddr, NULL); + if (ret) + return ret; + + if (copy_all) { + ret = copy_mc_to_kernel(daddr, saddr, length); + return ret ? -EIO : 0; + } + + /* Copy the head part of the range. Note: we pass offset as length. */ + if (head_off) { + ret = copy_mc_to_kernel(daddr, saddr, head_off); + if (ret) + return -EIO; + } + + /* Copy the tail part of the range */ + if (end < pg_end) { + loff_t tail_off = head_off + length; + loff_t tail_len = pg_end - end; + + ret = copy_mc_to_kernel(daddr + tail_off, saddr + tail_off, + tail_len); + if (ret) + return -EIO; + } + return 0; +} + /* * The user has performed a load from a hole in the file. Allocating a new * page in the file would cause excessive storage usage for workloads with @@ -1167,11 +1222,12 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, struct dax_device *dax_dev = iomap->dax_dev; struct iov_iter *iter = data; loff_t end = pos + length, done = 0; + bool write = iov_iter_rw(iter) == WRITE; ssize_t ret = 0; size_t xfer; int id; - if (iov_iter_rw(iter) == READ) { + if (!write) { end = min(end, i_size_read(inode)); if (pos >= end) return 0; @@ -1180,7 +1236,8 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, return iov_iter_zero(min(length, end - pos), iter); } - if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED)) + if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED && + !(iomap->flags & IOMAP_F_SHARED))) return -EIO; /* @@ -1219,6 +1276,13 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, break; } + if (write && srcmap->addr != iomap->addr) { + ret = dax_iomap_cow_copy(pos, length, PAGE_SIZE, srcmap, + kaddr); + if (ret) + break; + } + map_len = PFN_PHYS(map_len); kaddr += offset; map_len -= offset; @@ -1230,7 +1294,7 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data, * validated via access_ok() in either vfs_read() or * vfs_write(), depending on which operation we are doing. */ - if (iov_iter_rw(iter) == WRITE) + if (write) xfer = dax_copy_from_iter(dax_dev, pgoff, kaddr, map_len, iter); else @@ -1382,6 +1446,7 @@ static vm_fault_t dax_fault_actor(struct vm_fault *vmf, pfn_t *pfnp, unsigned long entry_flags = pmd ? DAX_PMD : 0; int err = 0; pfn_t pfn; + void *kaddr; /* if we are reading UNWRITTEN and HOLE, return a hole. */ if (!write && @@ -1392,18 +1457,25 @@ static vm_fault_t dax_fault_actor(struct vm_fault *vmf, pfn_t *pfnp, return dax_pmd_load_hole(xas, vmf, iomap, entry); } - if (iomap->type != IOMAP_MAPPED) { + if (iomap->type != IOMAP_MAPPED && !(iomap->flags & IOMAP_F_SHARED)) { WARN_ON_ONCE(1); return pmd ? VM_FAULT_FALLBACK : VM_FAULT_SIGBUS; } - err = dax_iomap_direct_access(iomap, pos, size, NULL, &pfn); + err = dax_iomap_direct_access(iomap, pos, size, &kaddr, &pfn); if (err) return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err); *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, entry_flags, write && !sync); + if (write && + srcmap->addr != IOMAP_HOLE && srcmap->addr != iomap->addr) { + err = dax_iomap_cow_copy(pos, size, size, srcmap, kaddr); + if (err) + return dax_fault_return(err); + } + if (sync) return dax_fault_synchronous_pfnp(pfnp, pfn);