From patchwork Wed Sep 15 10:44:56 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Shiyang Ruan X-Patchwork-Id: 12495963 Received: from heian.cn.fujitsu.com (mail.cn.fujitsu.com [183.91.158.132]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 547753FC9 for ; Wed, 15 Sep 2021 10:45:40 +0000 (UTC) IronPort-Data: A9a23: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 IronPort-HdrOrdr: A9a23:jF+Tv64OtU+DoJTg0QPXwK3XdLJyesId70hD6qkRc3xom6Oj+vxG8M5w6faWslcssRMb9uxoUZPoKRjhHPZOkOos1NyZMDUO1lHHEL1f X-IronPort-AV: E=Sophos;i="5.85,295,1624291200"; d="scan'208";a="114519041" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 15 Sep 2021 18:45:39 +0800 Received: from G08CNEXMBPEKD04.g08.fujitsu.local (unknown [10.167.33.201]) by cn.fujitsu.com (Postfix) with ESMTP id 2ECC44D0D9D2; Wed, 15 Sep 2021 18:45:34 +0800 (CST) Received: from G08CNEXCHPEKD09.g08.fujitsu.local (10.167.33.85) by G08CNEXMBPEKD04.g08.fujitsu.local (10.167.33.201) with Microsoft SMTP Server (TLS) id 15.0.1497.23; Wed, 15 Sep 2021 18:45:28 +0800 Received: from irides.mr.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; Wed, 15 Sep 2021 18:45:27 +0800 From: Shiyang Ruan To: , , CC: , , , , , , , , , Goldwyn Rodrigues , Ritesh Harjani Subject: [PATCH v9 3/8] fsdax: Replace mmap entry in case of CoW Date: Wed, 15 Sep 2021 18:44:56 +0800 Message-ID: <20210915104501.4146910-4-ruansy.fnst@fujitsu.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210915104501.4146910-1-ruansy.fnst@fujitsu.com> References: <20210915104501.4146910-1-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: 2ECC44D0D9D2.A2F6D 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 Reported-by: kernel test robot --- fs/dax.c | 73 +++++++++++++++++++++++++++++++------------------------- 1 file changed, 40 insertions(+), 33 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index dded08be54dc..41c93929f20b 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -734,6 +734,23 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d 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 @@ -741,16 +758,19 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d * 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)) @@ -762,7 +782,7 @@ 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); @@ -786,6 +806,9 @@ 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; } @@ -1111,17 +1134,15 @@ 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); @@ -1130,7 +1151,7 @@ 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; @@ -1148,8 +1169,8 @@ 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); @@ -1381,17 +1402,6 @@ 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 @@ -1452,13 +1462,11 @@ 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; @@ -1471,8 +1479,8 @@ 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)) { @@ -1484,8 +1492,7 @@ 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->addr != IOMAP_HOLE && srcmap->addr != iomap->addr) { @@ -1494,7 +1501,7 @@ 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 */