From f80e1668888f34c0764822e74953c997daf2ccdb Mon Sep 17 00:00:00 2001
From: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Date: Thu, 1 Dec 2022 15:28:52 +0000
Subject: [PATCH] fsdax: invalidate pages when CoW
CoW changes the share state of a dax page, but the share count of the page
isn't updated. The next time access this page, it should have been a
newly accessed, but old association exists. So, we need to clear the
share state when CoW happens, in both dax_iomap_rw() and dax_zero_iter().
Link: https://lkml.kernel.org/r/1669908538-55-3-git-send-email-ruansy.fnst@fujitsu.com
Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
fs/dax.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index 84fadea087051..c975d075e77b0 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1264,6 +1264,15 @@ static s64 dax_zero_iter(struct iomap_iter *iter, bool *did_zero)
if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
return length;
+ /*
+ * invalidate the pages whose sharing state is to be changed
+ * because of CoW.
+ */
+ if (iomap->flags & IOMAP_F_SHARED)
+ invalidate_inode_pages2_range(iter->inode->i_mapping,
+ pos >> PAGE_SHIFT,
+ (pos + length - 1) >> PAGE_SHIFT);
+
do {
unsigned offset = offset_in_page(pos);
unsigned size = min_t(u64, PAGE_SIZE - offset, length);
@@ -1324,12 +1333,13 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
struct iov_iter *iter)
{
const struct iomap *iomap = &iomi->iomap;
- const struct iomap *srcmap = &iomi->srcmap;
+ const struct iomap *srcmap = iomap_iter_srcmap(iomi);
loff_t length = iomap_length(iomi);
loff_t pos = iomi->pos;
struct dax_device *dax_dev = iomap->dax_dev;
loff_t end = pos + length, done = 0;
bool write = iov_iter_rw(iter) == WRITE;
+ bool cow = write && iomap->flags & IOMAP_F_SHARED;
ssize_t ret = 0;
size_t xfer;
int id;
@@ -1356,7 +1366,7 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
* into page tables. We have to tear down these mappings so that data
* written by write(2) is visible in mmap.
*/
- if (iomap->flags & IOMAP_F_NEW) {
+ if (iomap->flags & IOMAP_F_NEW || cow) {
invalidate_inode_pages2_range(iomi->inode->i_mapping,
pos >> PAGE_SHIFT,
(end - 1) >> PAGE_SHIFT);
@@ -1390,8 +1400,7 @@ static loff_t dax_iomap_iter(const struct iomap_iter *iomi,
break;
}
- if (write &&
- srcmap->type != IOMAP_HOLE && srcmap->addr != iomap->addr) {
+ if (cow) {
ret = dax_iomap_cow_copy(pos, length, PAGE_SIZE, srcmap,
kaddr);
if (ret)
--
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