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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 ABF1DC7C865 for ; Mon, 27 Apr 2020 08:48:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9467A2080C for ; Mon, 27 Apr 2020 08:48:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726937AbgD0Isw (ORCPT ); Mon, 27 Apr 2020 04:48:52 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:3131 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726883AbgD0Isr (ORCPT ); Mon, 27 Apr 2020 04:48:47 -0400 X-IronPort-AV: E=Sophos;i="5.73,323,1583164800"; d="scan'208";a="90547667" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 27 Apr 2020 16:48:38 +0800 Received: from G08CNEXMBPEKD06.g08.fujitsu.local (unknown [10.167.33.206]) by cn.fujitsu.com (Postfix) with ESMTP id 5ACCE50A9991; Mon, 27 Apr 2020 16:37:54 +0800 (CST) Received: from G08CNEXCHPEKD05.g08.fujitsu.local (10.167.33.203) by G08CNEXMBPEKD06.g08.fujitsu.local (10.167.33.206) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 27 Apr 2020 16:48:34 +0800 Received: from localhost.localdomain (10.167.225.141) by G08CNEXCHPEKD05.g08.fujitsu.local (10.167.33.209) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Mon, 27 Apr 2020 16:48:36 +0800 From: Shiyang Ruan To: , , CC: , , , , , , , , , Goldwyn Rodrigues Subject: [RFC PATCH 5/8] fs/dax: replace mmap entry in case of CoW Date: Mon, 27 Apr 2020 16:47:47 +0800 Message-ID: <20200427084750.136031-6-ruansy.fnst@cn.fujitsu.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200427084750.136031-1-ruansy.fnst@cn.fujitsu.com> References: <20200427084750.136031-1-ruansy.fnst@cn.fujitsu.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-yoursite-MailScanner-ID: 5ACCE50A9991.AF0B6 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: ruansy.fnst@cn.fujitsu.com Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We replace the existing entry to the newly allocated one in case of CoW. Also, we mark the entry as PAGECACHE_TAG_TOWRITE so writeback marks this entry as writeprotected. This helps us snapshots so new write pagefaults after snapshots trigger a CoW. Signed-off-by: Goldwyn Rodrigues Signed-off-by: Shiyang Ruan --- fs/dax.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 13a6a1d3c3b3..12096edb2569 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -835,6 +835,9 @@ static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev, return 0; } +#define DAX_IF_DIRTY (1ULL << 0) +#define DAX_IF_COW (1ULL << 1) + /* * By this point grab_mapping_entry() has ensured that we have a locked entry * of the appropriate size so we don't have to worry about downgrading PMDs to @@ -844,14 +847,17 @@ static int copy_user_dax(struct block_device *bdev, struct dax_device *dax_dev, */ static void *dax_insert_entry(struct xa_state *xas, struct address_space *mapping, struct vm_fault *vmf, - void *entry, pfn_t pfn, unsigned long flags, bool dirty) + void *entry, pfn_t pfn, unsigned long flags, + unsigned int insert_flags) { void *new_entry = dax_make_entry(pfn, flags); + bool dirty = insert_flags & DAX_IF_DIRTY; + bool cow = insert_flags & DAX_IF_COW; if (dirty) __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); - if (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE)) { + if (cow || (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE))) { unsigned long index = xas->xa_index; /* we are replacing a zero page with block mapping */ if (dax_is_pmd_entry(entry)) @@ -863,7 +869,7 @@ static void *dax_insert_entry(struct xa_state *xas, xas_reset(xas); xas_lock_irq(xas); - if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { + if (cow || dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { void *old; dax_disassociate_entry(entry, mapping, xas->xa_index, false); @@ -887,6 +893,9 @@ static void *dax_insert_entry(struct xa_state *xas, if (dirty) xas_set_mark(xas, PAGECACHE_TAG_DIRTY); + if (cow) + xas_set_mark(xas, PAGECACHE_TAG_TOWRITE); + xas_unlock_irq(xas); return entry; } @@ -1430,6 +1439,7 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, void *entry; pfn_t pfn; void *kaddr; + unsigned long insert_flags = 0; trace_dax_pte_fault(inode, vmf, ret); /* @@ -1522,8 +1532,10 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, if (error < 0) goto error_finish_iomap; - entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn, - 0, write && !sync); + if (write && !sync) + insert_flags |= DAX_IF_DIRTY; + entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn, 0, + insert_flags); if (srcmap.type != IOMAP_HOLE) { error = dax_copy_edges(pos, PAGE_SIZE, &srcmap, kaddr, @@ -1555,8 +1567,10 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, goto finish_iomap; case IOMAP_UNWRITTEN: - if (srcmap.type != IOMAP_HOLE) + if (srcmap.type != IOMAP_HOLE) { + insert_flags |= DAX_IF_COW; goto cow; + } /*FALLTHRU*/ case IOMAP_HOLE: if (!write) { @@ -1614,7 +1628,7 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, pfn = page_to_pfn_t(zero_page); *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, - DAX_PMD | DAX_ZERO_PAGE, false); + DAX_PMD | DAX_ZERO_PAGE, 0); if (arch_needs_pgtable_deposit()) { pgtable = pte_alloc_one(vma->vm_mm); @@ -1666,6 +1680,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, int error; pfn_t pfn; void *kaddr; + unsigned long insert_flags = 0; /* * Check whether offset isn't beyond end of file now. Caller is @@ -1753,8 +1768,10 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, if (error < 0) goto finish_iomap; + if (write && !sync) + insert_flags |= DAX_IF_DIRTY; entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn, - DAX_PMD, write && !sync); + DAX_PMD, insert_flags); if (srcmap.type != IOMAP_HOLE) { error = dax_copy_edges(pos, PMD_SIZE, &srcmap, kaddr, @@ -1781,8 +1798,10 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp, result = vmf_insert_pfn_pmd(vmf, pfn, write); break; case IOMAP_UNWRITTEN: - if (srcmap.type != IOMAP_HOLE) + if (srcmap.type != IOMAP_HOLE) { + insert_flags |= DAX_IF_COW; goto cow; + } /*FALLTHRU*/ case IOMAP_HOLE: if (WARN_ON_ONCE(write)) -- 2.26.2