From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: linux-btrfs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, jack@suse.cz, david@fromorbit.com,
willy@infradead.org, hch@lst.de, darrick.wong@oracle.com,
kilobyte@angband.pl, dsterba@suse.cz, nborisov@suse.com,
linux-nvdimm@lists.01.org, Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: [PATCH 10/18] dax: replace mmap entry in case of CoW
Date: Tue, 16 Apr 2019 11:41:46 -0500 [thread overview]
Message-ID: <20190416164154.30390-11-rgoldwyn@suse.de> (raw)
In-Reply-To: <20190416164154.30390-1-rgoldwyn@suse.de>
From: Goldwyn Rodrigues <rgoldwyn@suse.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>
---
fs/dax.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 45fc2e18969a..d5100cbe8bd2 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -708,14 +708,15 @@ 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, bool dirty,
+ bool cow)
{
void *new_entry = dax_make_entry(pfn, flags);
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))
@@ -727,12 +728,12 @@ 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
@@ -752,6 +753,9 @@ 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;
}
@@ -1031,7 +1035,7 @@ 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, false, false);
ret = vmf_insert_mixed(vmf->vma, vaddr, pfn);
trace_dax_load_hole(inode, vmf, ret);
@@ -1388,7 +1392,8 @@ static vm_fault_t dax_iomap_pte_fault(struct vm_fault *vmf, pfn_t *pfnp,
memset(addr, 0, PAGE_SIZE);
}
entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn,
- 0, write && !sync);
+ 0, write && !sync,
+ iomap.type == IOMAP_DAX_COW);
/*
* If we are doing synchronous page fault and inode needs fsync,
@@ -1467,7 +1472,8 @@ 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, false,
+ iomap->type == IOMAP_DAX_COW);
ptl = pmd_lock(vmf->vma->vm_mm, vmf->pmd);
if (!pmd_none(*(vmf->pmd))) {
@@ -1590,7 +1596,8 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
goto finish_iomap;
entry = dax_insert_entry(&xas, mapping, vmf, entry, pfn,
- DAX_PMD, write && !sync);
+ DAX_PMD, write && !sync,
+ false);
/*
* If we are doing synchronous page fault and inode needs fsync,
--
2.16.4
next prev parent reply other threads:[~2019-04-16 16:42 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-16 16:41 [PATCH v3 00/18] btrfs dax support Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 01/18] btrfs: create a mount option for dax Goldwyn Rodrigues
2019-04-16 16:52 ` Dan Williams
2019-04-16 16:41 ` [PATCH 02/18] btrfs: Carve out btrfs_get_extent_map_write() out of btrfs_get_blocks_write() Goldwyn Rodrigues
2019-04-16 23:45 ` Elliott, Robert (Servers)
2019-04-16 16:41 ` [PATCH 03/18] btrfs: basic dax read Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 04/18] dax: Introduce IOMAP_DAX_COW to CoW edges during writes Goldwyn Rodrigues
2019-04-17 16:46 ` Darrick J. Wong
2019-04-16 16:41 ` [PATCH 05/18] btrfs: return whether extent is nocow or not Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 06/18] btrfs: Rename __endio_write_update_ordered() to btrfs_update_ordered_extent() Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 07/18] btrfs: add dax write support Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 08/18] dax: memcpy page in case of IOMAP_DAX_COW for mmap faults Goldwyn Rodrigues
2019-04-17 16:52 ` Darrick J. Wong
2019-04-16 16:41 ` [PATCH 09/18] btrfs: Add dax specific address_space_operations Goldwyn Rodrigues
2019-04-16 16:41 ` Goldwyn Rodrigues [this message]
2019-04-17 15:24 ` [PATCH 10/18] dax: replace mmap entry in case of CoW Darrick J. Wong
2019-04-16 16:41 ` [PATCH 11/18] btrfs: add dax mmap support Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 12/18] btrfs: allow MAP_SYNC mmap Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 13/18] fs: dedup file range to use a compare function Goldwyn Rodrigues
2019-04-17 15:36 ` Darrick J. Wong
2019-04-16 16:41 ` [PATCH 14/18] dax: memcpy before zeroing range Goldwyn Rodrigues
2019-04-17 15:45 ` Darrick J. Wong
2019-04-17 16:39 ` Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 15/18] btrfs: handle dax page zeroing Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 16/18] btrfs: Writeprotect mmap pages on snapshot Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 17/18] btrfs: Disable dax-based defrag and send Goldwyn Rodrigues
2019-04-16 16:41 ` [PATCH 18/18] btrfs: trace functions for btrfs_iomap_begin/end Goldwyn Rodrigues
2019-04-17 16:49 ` [PATCH v3 00/18] btrfs dax support Adam Borowski
2019-04-29 17:26 [PATCH v4 " Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 10/18] dax: replace mmap entry in case of CoW Goldwyn Rodrigues
2019-05-21 17:35 ` Darrick J. Wong
2019-05-23 13:38 ` Jan Kara
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