From patchwork Sun May 8 14:36:16 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shiyang Ruan X-Patchwork-Id: 12842393 Received: from heian.cn.fujitsu.com (mail.cn.fujitsu.com [183.91.158.132]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 44E4D1856 for ; Sun, 8 May 2022 14:36:43 +0000 (UTC) IronPort-Data: A9a23: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 IronPort-HdrOrdr: A9a23:loNhKKoDNew1bswG0vmCZHgaV5rPeYIsimQD101hICG8cqSj+fxG+85rsyMc6QxhIU3I9urhBEDtex/hHNtOkOws1NSZLW7bUQmTXeJfBOLZqlWKcUDDH6xmpMNdmsNFaeEYY2IUsS+D2njbLz8/+qj7zImYwffZ02x2TRxnL4Vp7wJCAA6dFUFsLTM2fqYRJd6N4NZdvTq8dTAyZsS/PHMMWO/OvJnlj5TjCCR2fSIP2U2fiy+y8r7mH1y91hcaaTlGxrAv6izkvmXCl92ej80= X-IronPort-AV: E=Sophos;i="5.88,333,1635177600"; d="scan'208";a="124075742" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 08 May 2022 22:36:31 +0800 Received: from G08CNEXMBPEKD05.g08.fujitsu.local (unknown [10.167.33.204]) by cn.fujitsu.com (Postfix) with ESMTP id 764594D1719A; Sun, 8 May 2022 22:36:30 +0800 (CST) Received: from G08CNEXCHPEKD09.g08.fujitsu.local (10.167.33.85) by G08CNEXMBPEKD05.g08.fujitsu.local (10.167.33.204) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Sun, 8 May 2022 22:36:33 +0800 Received: from irides.mr.mr (10.167.225.141) by G08CNEXCHPEKD09.g08.fujitsu.local (10.167.33.209) with Microsoft SMTP Server id 15.0.1497.23 via Frontend Transport; Sun, 8 May 2022 22:36:28 +0800 From: Shiyang Ruan To: , , , , CC: , , , , , , , , , , Goldwyn Rodrigues , Christoph Hellwig , Ritesh Harjani Subject: [PATCH v11 03/07] fsdax: Replace mmap entry in case of CoW Date: Sun, 8 May 2022 22:36:16 +0800 Message-ID: <20220508143620.1775214-11-ruansy.fnst@fujitsu.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220508143620.1775214-1-ruansy.fnst@fujitsu.com> References: <20220508143620.1775214-1-ruansy.fnst@fujitsu.com> Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-yoursite-MailScanner-ID: 764594D1719A.AFF7C X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: ruansy.fnst@fujitsu.com X-Spam-Status: No 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 Reviewed-by: Darrick J. Wong --- fs/dax.c | 77 ++++++++++++++++++++++++++++++-------------------------- 1 file changed, 42 insertions(+), 35 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 00d2cb72ec58..78e26204697b 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -828,6 +828,23 @@ static int copy_cow_page_dax(struct vm_fault *vmf, const struct iomap_iter *iter return 0; } +/* + * MAP_SYNC on a dax mapping guarantees dirty metadata is + * flushed on write-faults (non-cow), but not read-faults. + */ +static bool dax_fault_is_synchronous(const struct iomap_iter *iter, + struct vm_area_struct *vma) +{ + return (iter->flags & IOMAP_WRITE) && (vma->vm_flags & VM_SYNC) && + (iter->iomap.flags & IOMAP_F_DIRTY); +} + +static bool dax_fault_is_cow(const struct iomap_iter *iter) +{ + return (iter->flags & IOMAP_WRITE) && + (iter->iomap.flags & IOMAP_F_SHARED); +} + /* * 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 @@ -835,16 +852,19 @@ static int copy_cow_page_dax(struct vm_fault *vmf, const struct iomap_iter *iter * 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, + const struct iomap_iter *iter, void *entry, pfn_t pfn, + unsigned long flags) { + struct address_space *mapping = vmf->vma->vm_file->f_mapping; void *new_entry = dax_make_entry(pfn, flags); + bool dirty = !dax_fault_is_synchronous(iter, vmf->vma); + bool cow = dax_fault_is_cow(iter); 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)) @@ -856,12 +876,12 @@ 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); dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address, - false); + cow); /* * 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 @@ -881,6 +901,9 @@ 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; } @@ -1122,17 +1145,15 @@ static int dax_iomap_cow_copy(loff_t pos, uint64_t length, size_t align_size, * If this page is ever written to we will re-fault and change the mapping to * point to real DAX storage instead. */ -static vm_fault_t dax_load_hole(struct xa_state *xas, - struct address_space *mapping, void **entry, - struct vm_fault *vmf) +static vm_fault_t dax_load_hole(struct xa_state *xas, struct vm_fault *vmf, + const struct iomap_iter *iter, void **entry) { - struct inode *inode = mapping->host; + struct inode *inode = iter->inode; unsigned long vaddr = vmf->address; 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, iter, *entry, pfn, DAX_ZERO_PAGE); ret = vmf_insert_mixed(vmf->vma, vaddr, pfn); trace_dax_load_hole(inode, vmf, ret); @@ -1141,7 +1162,7 @@ static vm_fault_t dax_load_hole(struct xa_state *xas, #ifdef CONFIG_FS_DAX_PMD static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, - const struct iomap *iomap, void **entry) + const struct iomap_iter *iter, void **entry) { struct address_space *mapping = vmf->vma->vm_file->f_mapping; unsigned long pmd_addr = vmf->address & PMD_MASK; @@ -1159,8 +1180,8 @@ 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, iter, *entry, pfn, + DAX_PMD | DAX_ZERO_PAGE); if (arch_needs_pgtable_deposit()) { pgtable = pte_alloc_one(vma->vm_mm); @@ -1193,7 +1214,7 @@ static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, } #else static vm_fault_t dax_pmd_load_hole(struct xa_state *xas, struct vm_fault *vmf, - const struct iomap *iomap, void **entry) + const struct iomap_iter *iter, void **entry) { return VM_FAULT_FALLBACK; } @@ -1427,17 +1448,6 @@ static vm_fault_t dax_fault_return(int error) return vmf_error(error); } -/* - * MAP_SYNC on a dax mapping guarantees dirty metadata is - * flushed on write-faults (non-cow), but not read-faults. - */ -static bool dax_fault_is_synchronous(unsigned long flags, - struct vm_area_struct *vma, const struct iomap *iomap) -{ - return (flags & IOMAP_WRITE) && (vma->vm_flags & VM_SYNC) - && (iomap->flags & IOMAP_F_DIRTY); -} - /* * When handling a synchronous page fault and the inode need a fsync, we can * insert the PTE/PMD into page tables only after that fsync happened. Skip @@ -1495,13 +1505,11 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf, const struct iomap_iter *iter, pfn_t *pfnp, struct xa_state *xas, void **entry, bool pmd) { - struct address_space *mapping = vmf->vma->vm_file->f_mapping; const struct iomap *iomap = &iter->iomap; const struct iomap *srcmap = &iter->srcmap; size_t size = pmd ? PMD_SIZE : PAGE_SIZE; loff_t pos = (loff_t)xas->xa_index << PAGE_SHIFT; - bool write = vmf->flags & FAULT_FLAG_WRITE; - bool sync = dax_fault_is_synchronous(iter->flags, vmf->vma, iomap); + bool write = iter->flags & IOMAP_WRITE; unsigned long entry_flags = pmd ? DAX_PMD : 0; int err = 0; pfn_t pfn; @@ -1514,8 +1522,8 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf, if (!write && (iomap->type == IOMAP_UNWRITTEN || iomap->type == IOMAP_HOLE)) { if (!pmd) - return dax_load_hole(xas, mapping, entry, vmf); - return dax_pmd_load_hole(xas, vmf, iomap, entry); + return dax_load_hole(xas, vmf, iter, entry); + return dax_pmd_load_hole(xas, vmf, iter, entry); } if (iomap->type != IOMAP_MAPPED && !(iomap->flags & IOMAP_F_SHARED)) { @@ -1527,8 +1535,7 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf, if (err) return pmd ? VM_FAULT_FALLBACK : dax_fault_return(err); - *entry = dax_insert_entry(xas, mapping, vmf, *entry, pfn, entry_flags, - write && !sync); + *entry = dax_insert_entry(xas, vmf, iter, *entry, pfn, entry_flags); if (write && srcmap->type != IOMAP_HOLE && srcmap->addr != iomap->addr) { @@ -1537,7 +1544,7 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf, return dax_fault_return(err); } - if (sync) + if (dax_fault_is_synchronous(iter, vmf->vma)) return dax_fault_synchronous_pfnp(pfnp, pfn); /* insert PMD pfn */