From: Shiyang Ruan <ruansy.fnst@fujitsu.com>
To: <djwong@kernel.org>, <hch@lst.de>, <linux-xfs@vger.kernel.org>
Cc: <ruansy.fnst@fujitsu.com>, <dan.j.williams@intel.com>,
<david@fromorbit.com>, <linux-fsdevel@vger.kernel.org>,
<linux-kernel@vger.kernel.org>, <nvdimm@lists.linux.dev>,
<rgoldwyn@suse.de>, <viro@zeniv.linux.org.uk>,
<willy@infradead.org>, Goldwyn Rodrigues <rgoldwyn@suse.com>,
Ritesh Harjani <riteshh@linux.ibm.com>
Subject: [PATCH v7 3/8] fsdax: Replace mmap entry in case of CoW
Date: Mon, 16 Aug 2021 14:03:54 +0800 [thread overview]
Message-ID: <20210816060359.1442450-4-ruansy.fnst@fujitsu.com> (raw)
In-Reply-To: <20210816060359.1442450-1-ruansy.fnst@fujitsu.com>
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 <rgoldwyn@suse.com>
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
fs/dax.c | 39 ++++++++++++++++++++++++++++-----------
1 file changed, 28 insertions(+), 11 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 697a7b7bb96f..e49ba68cc7e4 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -734,6 +734,10 @@ static int copy_cow_page_dax(struct block_device *bdev, struct dax_device *dax_d
return 0;
}
+/* DAX Insert Flag: The state of the entry we insert */
+#define DAX_IF_DIRTY (1 << 0)
+#define DAX_IF_COW (1 << 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
@@ -741,16 +745,19 @@ 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,
+ void *entry, pfn_t pfn, unsigned long flags,
+ unsigned int insert_flags)
{
+ struct address_space *mapping = vmf->vma->vm_file->f_mapping;
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))
@@ -762,7 +769,7 @@ 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 +793,9 @@ 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;
}
@@ -1121,8 +1131,7 @@ static vm_fault_t dax_load_hole(struct xa_state *xas,
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, *entry, pfn, DAX_ZERO_PAGE, 0);
ret = vmf_insert_mixed(vmf->vma, vaddr, pfn);
trace_dax_load_hole(inode, vmf, ret);
@@ -1149,8 +1158,8 @@ 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, *entry, pfn,
+ DAX_PMD | DAX_ZERO_PAGE, 0);
if (arch_needs_pgtable_deposit()) {
pgtable = pte_alloc_one(vma->vm_mm);
@@ -1461,6 +1470,7 @@ static vm_fault_t dax_fault_iter(struct vm_fault *vmf,
bool write = vmf->flags & FAULT_FLAG_WRITE;
bool sync = dax_fault_is_synchronous(iter->flags, vmf->vma, iomap);
unsigned long entry_flags = pmd ? DAX_PMD : 0;
+ unsigned int insert_flags = 0;
int err = 0;
pfn_t pfn;
void *kaddr;
@@ -1485,8 +1495,15 @@ 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);
+ if (write) {
+ if (!sync)
+ insert_flags |= DAX_IF_DIRTY;
+ if (iomap->flags & IOMAP_F_SHARED)
+ insert_flags |= DAX_IF_COW;
+ }
+
+ *entry = dax_insert_entry(xas, vmf, *entry, pfn, entry_flags,
+ insert_flags);
if (write &&
srcmap->addr != IOMAP_HOLE && srcmap->addr != iomap->addr) {
--
2.32.0
next prev parent reply other threads:[~2021-08-16 6:04 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-16 6:03 [PATCH v7 0/8] fsdax,xfs: Add reflink&dedupe support for fsdax Shiyang Ruan
2021-08-16 6:03 ` [PATCH v7 1/8] fsdax: Output address in dax_iomap_pfn() and rename it Shiyang Ruan
2021-08-18 21:01 ` Dan Williams
2021-08-16 6:03 ` [PATCH v7 2/8] fsdax: Introduce dax_iomap_cow_copy() Shiyang Ruan
2021-08-19 22:35 ` Dan Williams
2021-08-20 5:59 ` ruansy.fnst
2021-08-16 6:03 ` Shiyang Ruan [this message]
2021-08-19 22:54 ` [PATCH v7 3/8] fsdax: Replace mmap entry in case of CoW Dan Williams
2021-08-23 12:57 ` Christoph Hellwig
2021-08-27 3:22 ` Shiyang Ruan
2021-08-27 5:00 ` Dan Williams
2021-08-27 5:26 ` Shiyang Ruan
2021-08-16 6:03 ` [PATCH v7 4/8] fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero Shiyang Ruan
2021-08-20 2:39 ` Dan Williams
2021-08-27 3:23 ` Shiyang Ruan
2021-08-16 6:03 ` [PATCH v7 5/8] iomap: Introduce iomap_iter2 for two files Shiyang Ruan
2021-08-23 12:58 ` Christoph Hellwig
2021-08-16 6:03 ` [PATCH v7 6/8] fsdax: Dedup file range to use a compare function Shiyang Ruan
2021-08-23 13:16 ` Christoph Hellwig
2021-08-16 6:03 ` [PATCH v7 7/8] fsdax: Introduce dax_iomap_ops for end of reflink Shiyang Ruan
2021-08-20 3:01 ` Dan Williams
2021-08-20 6:13 ` ruansy.fnst
2021-08-20 15:18 ` Dan Williams
2021-08-23 13:02 ` Christoph Hellwig
2021-08-27 3:29 ` Shiyang Ruan
2021-08-27 5:04 ` Dan Williams
2021-08-27 5:27 ` Shiyang Ruan
2021-08-16 6:03 ` [PATCH v7 8/8] fs/xfs: Add dax dedupe support Shiyang Ruan
2021-08-20 3:08 ` Dan Williams
2021-08-27 3:36 ` Shiyang Ruan
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