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=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 29248C7C862 for ; Mon, 27 Apr 2020 08:48:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D36FF21D7B for ; Mon, 27 Apr 2020 08:48:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D36FF21D7B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=cn.fujitsu.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 479098E000A; Mon, 27 Apr 2020 04:48:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 400968E000E; Mon, 27 Apr 2020 04:48:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2A23C8E000A; Mon, 27 Apr 2020 04:48:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0059.hostedemail.com [216.40.44.59]) by kanga.kvack.org (Postfix) with ESMTP id 08C958E000E for ; Mon, 27 Apr 2020 04:48:46 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id B09A58248047 for ; Mon, 27 Apr 2020 08:48:45 +0000 (UTC) X-FDA: 76753009410.17.rice51_2f09460fa0339 X-HE-Tag: rice51_2f09460fa0339 X-Filterd-Recvd-Size: 6814 Received: from heian.cn.fujitsu.com (mail.cn.fujitsu.com [183.91.158.132]) by imf30.hostedemail.com (Postfix) with ESMTP for ; Mon, 27 Apr 2020 08:48:42 +0000 (UTC) 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-Type: text/plain X-yoursite-MailScanner-ID: 5ACCE50A9991.AF0B6 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: ruansy.fnst@cn.fujitsu.com Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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, s= truct dax_device *dax_dev, return 0; } =20 +#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 P= MDs 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 =3D dax_make_entry(pfn, flags); + bool dirty =3D insert_flags & DAX_IF_DIRTY; + bool cow =3D insert_flags & DAX_IF_COW; =20 if (dirty) __mark_inode_dirty(mapping->host, I_DIRTY_PAGES); =20 - if (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE)) { + if (cow || (dax_is_zero_entry(entry) && !(flags & DAX_ZERO_PAGE))) { unsigned long index =3D 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, =20 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; =20 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); =20 + 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_fau= lt *vmf, pfn_t *pfnp, void *entry; pfn_t pfn; void *kaddr; + unsigned long insert_flags =3D 0; =20 trace_dax_pte_fault(inode, vmf, ret); /* @@ -1522,8 +1532,10 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fa= ult *vmf, pfn_t *pfnp, if (error < 0) goto error_finish_iomap; =20 - entry =3D dax_insert_entry(&xas, mapping, vmf, entry, pfn, - 0, write && !sync); + if (write && !sync) + insert_flags |=3D DAX_IF_DIRTY; + entry =3D dax_insert_entry(&xas, mapping, vmf, entry, pfn, 0, + insert_flags); =20 if (srcmap.type !=3D IOMAP_HOLE) { error =3D dax_copy_edges(pos, PAGE_SIZE, &srcmap, kaddr, @@ -1555,8 +1567,10 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fa= ult *vmf, pfn_t *pfnp, =20 goto finish_iomap; case IOMAP_UNWRITTEN: - if (srcmap.type !=3D IOMAP_HOLE) + if (srcmap.type !=3D IOMAP_HOLE) { + insert_flags |=3D 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, =20 pfn =3D page_to_pfn_t(zero_page); *entry =3D dax_insert_entry(xas, mapping, vmf, *entry, pfn, - DAX_PMD | DAX_ZERO_PAGE, false); + DAX_PMD | DAX_ZERO_PAGE, 0); =20 if (arch_needs_pgtable_deposit()) { pgtable =3D pte_alloc_one(vma->vm_mm); @@ -1666,6 +1680,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fau= lt *vmf, pfn_t *pfnp, int error; pfn_t pfn; void *kaddr; + unsigned long insert_flags =3D 0; =20 /* * 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_fa= ult *vmf, pfn_t *pfnp, if (error < 0) goto finish_iomap; =20 + if (write && !sync) + insert_flags |=3D DAX_IF_DIRTY; entry =3D dax_insert_entry(&xas, mapping, vmf, entry, pfn, - DAX_PMD, write && !sync); + DAX_PMD, insert_flags); =20 if (srcmap.type !=3D IOMAP_HOLE) { error =3D dax_copy_edges(pos, PMD_SIZE, &srcmap, kaddr, @@ -1781,8 +1798,10 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fa= ult *vmf, pfn_t *pfnp, result =3D vmf_insert_pfn_pmd(vmf, pfn, write); break; case IOMAP_UNWRITTEN: - if (srcmap.type !=3D IOMAP_HOLE) + if (srcmap.type !=3D IOMAP_HOLE) { + insert_flags |=3D DAX_IF_COW; goto cow; + } /*FALLTHRU*/ case IOMAP_HOLE: if (WARN_ON_ONCE(write)) --=20 2.26.2