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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 D0923C433E0 for ; Tue, 16 Feb 2021 13:14:00 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2E90864D73 for ; Tue, 16 Feb 2021 13:13:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2E90864D73 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 98B43100EB835; Tue, 16 Feb 2021 05:13:59 -0800 (PST) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=195.135.220.15; helo=mx2.suse.de; envelope-from=dsterba@suse.cz; receiver= Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id AC3F1100EBBC1 for ; Tue, 16 Feb 2021 05:13:53 -0800 (PST) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 9D362ACBF; Tue, 16 Feb 2021 13:13:51 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 8C951DA6EF; Tue, 16 Feb 2021 14:11:54 +0100 (CET) Date: Tue, 16 Feb 2021 14:11:54 +0100 From: David Sterba To: Shiyang Ruan Subject: Re: [PATCH 4/7] fsdax: Replace mmap entry in case of CoW Message-ID: <20210216131154.GN1993@twin.jikos.cz> Mail-Followup-To: dsterba@suse.cz, Shiyang Ruan , linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, darrick.wong@oracle.com, dan.j.williams@intel.com, willy@infradead.org, jack@suse.cz, viro@zeniv.linux.org.uk, linux-btrfs@vger.kernel.org, ocfs2-devel@oss.oracle.com, david@fromorbit.com, hch@lst.de, rgoldwyn@suse.de, Goldwyn Rodrigues References: <20210207170924.2933035-1-ruansy.fnst@cn.fujitsu.com> <20210207170924.2933035-5-ruansy.fnst@cn.fujitsu.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210207170924.2933035-5-ruansy.fnst@cn.fujitsu.com> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Message-ID-Hash: BHLYE7RMH3BDEKNTF2V5NP2A2BYL75BP X-Message-ID-Hash: BHLYE7RMH3BDEKNTF2V5NP2A2BYL75BP X-MailFrom: dsterba@suse.cz X-Mailman-Rule-Hits: nonmember-moderation X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation CC: linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, darrick.wong@oracle.com, willy@infradead.org, jack@suse.cz, viro@zeniv.linux.org.uk, linux-btrfs@vger.kernel.org, ocfs2-devel@oss.oracle.com, david@fromorbit.com, hch@lst.de, rgoldwyn@suse.de, Goldwyn Rodrigues X-Mailman-Version: 3.1.1 Precedence: list Reply-To: dsterba@suse.cz List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Mon, Feb 08, 2021 at 01:09:21AM +0800, Shiyang Ruan wrote: > 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 | 31 +++++++++++++++++++++++-------- > 1 file changed, 23 insertions(+), 8 deletions(-) > > diff --git a/fs/dax.c b/fs/dax.c > index b2195cbdf2dc..29698a3d2e37 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -722,6 +722,9 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d > return 0; > } > > +#define DAX_IF_DIRTY (1ULL << 0) > +#define DAX_IF_COW (1ULL << 1) The constants are ULL, but I see other flags only 'unsigned long' > + > /* > * 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 > @@ -731,14 +734,16 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d > */ > 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, bool insert_flags) insert_flags is bool > { > void *new_entry = dax_make_entry(pfn, flags); > + bool dirty = insert_flags & DAX_IF_DIRTY; "insert_flags & DAX_IF_DIRTY" is "bool & ULL", this can't be right > + bool cow = insert_flags & DAX_IF_COW; Same > > 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 +755,7 @@ 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 +779,9 @@ 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; > } > @@ -1319,6 +1327,7 @@ 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); > /* > @@ -1444,8 +1453,10 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, > > goto finish_iomap; > case IOMAP_UNWRITTEN: > - if (write && iomap.flags & IOMAP_F_SHARED) > + if (write && (iomap.flags & IOMAP_F_SHARED)) { > + insert_flags |= DAX_IF_COW; Here's an example of 'unsigned long = unsigned long long', though it'll work, it would be better to unify all the types. > goto cow; > + } > fallthrough; > case IOMAP_HOLE: > if (!write) { > @@ -1555,6 +1566,7 @@ 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 > @@ -1670,14 +1682,17 @@ 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 (write && iomap.flags & IOMAP_F_SHARED) > + if (write && (iomap.flags & IOMAP_F_SHARED)) { > + insert_flags |= DAX_IF_COW; > goto cow; > + } > fallthrough; > case IOMAP_HOLE: > - if (WARN_ON_ONCE(write)) > + if (!write) { > + result = dax_pmd_load_hole(&xas, vmf, &iomap, &entry); > break; > - result = dax_pmd_load_hole(&xas, vmf, &iomap, &entry); > - break; > + } > + fallthrough; > default: > WARN_ON_ONCE(1); > break; > -- > 2.30.0 > > _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org