From patchwork Thu Apr 8 12:04:27 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shiyang Ruan X-Patchwork-Id: 12190845 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=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 7CD32C43462 for ; Thu, 8 Apr 2021 12:04:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5AA336115B for ; Thu, 8 Apr 2021 12:04:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231455AbhDHMFG (ORCPT ); Thu, 8 Apr 2021 08:05:06 -0400 Received: from mail.cn.fujitsu.com ([183.91.158.132]:24833 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S231195AbhDHMFF (ORCPT ); Thu, 8 Apr 2021 08:05:05 -0400 IronPort-HdrOrdr: A9a23:5PmxU6DeRQQp96/lHelM55DYdL4zR+YMi2QD/UZ3VBBTb4ikh9mj9c5rsSPcpRQwfDUbmd6GMLSdWn+0z/NIyKQYILvKZmfbkUSlIIxo5YHhhx3McheVysdzzqFlGpIeNPTVLXxXyfn3+xO5FdFI+qjjzImNif3Fx3lgCSFGApsQjDtRMQqQHk1oSAQuP/NQe6a03NZNpDarZB0sH6aGL0QCNtKim/T70LriYTMjQyUs8RSyi1qTg4LSIly12Qg/Xlp0rYsfzQ== X-IronPort-AV: E=Sophos;i="5.82,206,1613404800"; d="scan'208";a="106797270" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 08 Apr 2021 20:04:52 +0800 Received: from G08CNEXMBPEKD05.g08.fujitsu.local (unknown [10.167.33.204]) by cn.fujitsu.com (Postfix) with ESMTP id C4A9D4CEA876; Thu, 8 Apr 2021 20:04:47 +0800 (CST) Received: from G08CNEXCHPEKD04.g08.fujitsu.local (10.167.33.200) by G08CNEXMBPEKD05.g08.fujitsu.local (10.167.33.204) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 8 Apr 2021 20:04:37 +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 20:04:37 +0800 From: Shiyang Ruan To: , , , CC: , , , , , , , , , Goldwyn Rodrigues , Ritesh Harjani Subject: [PATCH v4 2/7] fsdax: Replace mmap entry in case of CoW Date: Thu, 8 Apr 2021 20:04:27 +0800 Message-ID: <20210408120432.1063608-3-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: C4A9D4CEA876.A55FE X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: ruansy.fnst@fujitsu.com Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@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 Reviewed-by: Christoph Hellwig Reviewed-by: Ritesh Harjani --- fs/dax.c | 39 ++++++++++++++++++++++++++++----------- 1 file changed, 28 insertions(+), 11 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index b4fd3813457a..e6c1354b27a8 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -722,6 +722,10 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d return 0; } +/* DAX Insert Flag for the entry we insert */ +#define DAX_IF_DIRTY (1 << 0) +#define DAX_IF_COW (1 << 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 @@ -729,16 +733,19 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d * already in the tree, we will skip the insertion and just dirty the PMD as * appropriate. */ -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) +static void *dax_insert_entry(struct xa_state *xas, struct vm_fault *vmf, + void *entry, pfn_t pfn, unsigned long flags, + unsigned int insert_flags) { + struct address_space *mapping = vmf->vma->vm_file->f_mapping; 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)) @@ -750,7 +757,7 @@ 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, false); @@ -774,6 +781,9 @@ 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; } @@ -1109,8 +1119,7 @@ static vm_fault_t dax_load_hole(struct xa_state *xas, pfn_t pfn = pfn_to_pfn_t(my_zero_pfn(vaddr)); vm_fault_t ret; - *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, - DAX_ZERO_PAGE, false); + *entry = dax_insert_entry(xas, vmf, *entry, pfn, DAX_ZERO_PAGE, 0); ret = vmf_insert_mixed(vmf->vma, vaddr, pfn); trace_dax_load_hole(inode, vmf, ret); @@ -1137,8 +1146,8 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, goto fallback; pfn = page_to_pfn_t(zero_page); - *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, - DAX_PMD | DAX_ZERO_PAGE, false); + *entry = dax_insert_entry(xas, vmf, *entry, pfn, + DAX_PMD | DAX_ZERO_PAGE, 0); if (arch_needs_pgtable_deposit()) { pgtable = pte_alloc_one(vma->vm_mm); @@ -1444,6 +1453,7 @@ static vm_fault_t dax_fault_actor(struct vm_fault *vmf, pfn_t *pfnp, bool write = vmf->flags & FAULT_FLAG_WRITE; bool sync = dax_fault_is_synchronous(flags, vmf->vma, iomap); unsigned long entry_flags = pmd ? DAX_PMD : 0; + unsigned int insert_flags = 0; int err = 0; pfn_t pfn; void *kaddr; @@ -1466,8 +1476,15 @@ static vm_fault_t dax_fault_actor(struct vm_fault *vmf, pfn_t *pfnp, 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) { + if (!sync) + insert_flags |= DAX_IF_DIRTY; + if (iomap->flags & IOMAP_F_SHARED) + insert_flags |= DAX_IF_COW; + } + + *entry = dax_insert_entry(xas, vmf, *entry, pfn, entry_flags, + insert_flags); if (write && srcmap->addr != IOMAP_HOLE && srcmap->addr != iomap->addr) {