From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from heian.cn.fujitsu.com (mail.cn.fujitsu.com [183.91.158.132]) by ml01.01.org (Postfix) with ESMTP id 4536E212E844E for ; Wed, 31 Jul 2019 04:52:22 -0700 (PDT) From: Shiyang Ruan Subject: [RFC PATCH 3/7] dax: replace mmap entry in case of CoW Date: Wed, 31 Jul 2019 19:49:31 +0800 Message-ID: <20190731114935.11030-4-ruansy.fnst@cn.fujitsu.com> In-Reply-To: <20190731114935.11030-1-ruansy.fnst@cn.fujitsu.com> References: <20190731114935.11030-1-ruansy.fnst@cn.fujitsu.com> MIME-Version: 1.0 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: linux-xfs@vger.kernel.org, linux-nvdimm@lists.01.org, darrick.wong@oracle.com Cc: qi.fuli@fujitsu.com, gujx@cn.fujitsu.com, rgoldwyn@suse.de, david@fromorbit.com, linux-kernel@vger.kernel.org, Goldwyn Rodrigues List-ID: From: Goldwyn Rodrigues 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. btrfs does not support hugepages so we don't handle PMD. Signed-off-by: Goldwyn Rodrigues --- fs/dax.c | 36 ++++++++++++++++++++++++++++-------- 1 file changed, 28 insertions(+), 8 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 084cc21d47a4..8eb065a1ec51 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -700,6 +700,9 @@ 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 @@ -709,14 +712,17 @@ 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)) @@ -728,12 +734,12 @@ static void *dax_insert_entry(struct xa_state *xas, xas_reset(xas); xas_lock_irq(xas); - if (dax_entry_size(entry) != dax_entry_size(new_entry)) { + if (cow || (dax_entry_size(entry) != dax_entry_size(new_entry))) { dax_disassociate_entry(entry, mapping, false); dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address); } - if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { + if (cow || dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) { /* * Only swap our new entry into the page cache if the current * entry is a zero page or an empty entry. If a normal PTE or @@ -753,6 +759,9 @@ 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; } @@ -1040,7 +1049,7 @@ static vm_fault_t dax_load_hole(struct xa_state *xas, vm_fault_t ret; *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, - DAX_ZERO_PAGE, false); + DAX_ZERO_PAGE, 0); ret = vmf_insert_mixed(vmf->vma, vaddr, pfn); trace_dax_load_hole(inode, vmf, ret); @@ -1310,6 +1319,7 @@ 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); /* @@ -1371,6 +1381,8 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, error = copy_user_dax(iomap.bdev, iomap.dax_dev, sector, PAGE_SIZE, vmf->cow_page, vaddr); break; + case IOMAP_COW: + /* Should not be setting this - fallthrough */ default: WARN_ON_ONCE(1); error = -EIO; @@ -1391,6 +1403,8 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, switch (iomap.type) { case IOMAP_COW: + insert_flags |= DAX_IF_COW; + /* fallthrough */ case IOMAP_MAPPED: if (iomap.flags & IOMAP_F_NEW) { count_vm_event(PGMAJFAULT); @@ -1401,8 +1415,10 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp, if (error < 0) goto error_finish_iomap; + if (write && !sync) + insert_flags |= DAX_IF_DIRTY; entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn, - 0, write && !sync); + 0, insert_flags); if (iomap.type == IOMAP_COW) { error = dax_copy_edges(inode, pos, PAGE_SIZE, &srcmap, @@ -1490,7 +1506,7 @@ 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); @@ -1542,6 +1558,7 @@ 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 @@ -1627,8 +1644,11 @@ 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 (iomap.type == IOMAP_COW) { error = dax_copy_edges(inode, pos, PMD_SIZE, &srcmap, -- 2.17.0 _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm