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Tue, 16 Feb 2021 14:11:54 +0100 (CET) Date: Tue, 16 Feb 2021 14:11:54 +0100 From: David Sterba To: Shiyang Ruan 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) X-PDR: PASS X-Source-IP: 195.135.220.15 X-ServerName: mx2.suse.de X-Proofpoint-SPF-Result: pass X-Proofpoint-SPF-Record: v=spf1 ip4:137.65.0.0/16 ip4:151.155.28.0/17 ip4:149.44.0.0/16 ip4:147.2.0.0/16 ip4:164.99.0.0/16 ip4:130.57.0.0/16 ip4:192.31.114.0/24 ip4:195.135.221.0/24 ip4:195.135.220.0/24 ip4:69.7.179.0/24 ip4:150.215.214.0/24 include:mailcontrol.com ~all X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9896 signatures=668683 X-Proofpoint-Spam-Details: rule=tap_notspam policy=tap score=0 lowpriorityscore=0 adultscore=0 mlxlogscore=999 mlxscore=0 priorityscore=48 impostorscore=0 bulkscore=0 clxscore=255 spamscore=0 phishscore=0 suspectscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102160123 X-Spam: Clean Cc: jack@suse.cz, darrick.wong@oracle.com, linux-nvdimm@lists.01.org, david@fromorbit.com, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, ocfs2-devel@oss.oracle.com, viro@zeniv.linux.org.uk, Goldwyn Rodrigues , linux-fsdevel@vger.kernel.org, dan.j.williams@intel.com, linux-btrfs@vger.kernel.org Subject: Re: [Ocfs2-devel] [PATCH 4/7] fsdax: Replace mmap entry in case of CoW X-BeenThere: ocfs2-devel@oss.oracle.com X-Mailman-Version: 2.1.9 Precedence: list Reply-To: dsterba@suse.cz List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9896 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 adultscore=0 mlxscore=0 bulkscore=0 suspectscore=0 malwarescore=0 spamscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102160123 X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=9896 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 priorityscore=1501 lowpriorityscore=0 bulkscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 malwarescore=0 phishscore=0 clxscore=1034 mlxscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102160123 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 > > _______________________________________________ Ocfs2-devel mailing list Ocfs2-devel@oss.oracle.com https://oss.oracle.com/mailman/listinfo/ocfs2-devel