The patch titled
Subject: fsdax: invalidate pages when CoW
has been added to the -mm mm-unstable branch. Its filename is
fsdax-invalidate-pages-when-cow.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fsdax-invalidate-pages-when-cow.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
Subject: fsdax: invalidate pages when CoW
Date: Thu, 1 Dec 2022 15:28:52 +0000
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@xxxxxxxxxxx
Signed-off-by: Shiyang Ruan <ruansy.fnst@xxxxxxxxxxx>
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/dax.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
--- a/fs/dax.c~fsdax-invalidate-pages-when-cow
+++ a/fs/dax.c
@@ -1264,6 +1264,15 @@ static s64 dax_zero_iter(struct iomap_it
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 struc
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 struc
* 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 struc
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)
_
Patches currently in -mm which might be from ruansy.fnst@xxxxxxxxxxx are
fsdax-introduce-page-share-for-fsdax-in-reflink-mode.patch
fsdax-invalidate-pages-when-cow.patch
fsdax-zero-the-edges-if-source-is-hole-or-unwritten.patch
fsdaxxfs-set-the-shared-flag-when-file-extent-is-shared.patch
fsdax-dedupe-iter-two-files-at-the-same-time.patch
xfs-use-dax-ops-for-zero-and-truncate-in-fsdax-mode.patch
fsdaxxfs-port-unshare-to-fsdax.patch
xfs-remove-restrictions-for-fsdax-and-reflink.patch
