Commit f80e1668 authored by Shiyang Ruan's avatar Shiyang Ruan Committed by Andrew Morton
Browse files

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: default avatarShiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: default avatarDarrick 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 16900426

fs/dax.c

+13 −4
Original line number Diff line number Diff line
@@ -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)