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Commit 226fb99e authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Greg Kroah-Hartman
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dm writecache: handle DAX to partitions on persistent memory correctly 



commit f9e040efcc28309e5c592f7e79085a9a52e31f58 upstream.

The function dax_direct_access doesn't take partitions into account,
it always maps pages from the beginning of the device. Therefore,
persistent_memory_claim() must get the partition offset using
get_start_sect() and add it to the page offsets passed to
dax_direct_access().

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Fixes: 48debafe ("dm: add writecache target")
Cc: stable@vger.kernel.org # 4.18+
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6fb192c0

drivers/md/dm-writecache.c

+10 −2
Original line number Diff line number Diff line
@@ -224,6 +224,7 @@ static int persistent_memory_claim(struct dm_writecache *wc) 
	pfn_t pfn;

	int id;

	struct page **pages;

	sector_t offset;



	wc->memory_vmapped = false;
@@ -242,9 +243,16 @@ static int persistent_memory_claim(struct dm_writecache *wc) 
		goto err1;

	}



	offset = get_start_sect(wc->ssd_dev->bdev);

	if (offset & (PAGE_SIZE / 512 - 1)) {

		r = -EINVAL;

		goto err1;

	}

	offset >>= PAGE_SHIFT - 9;



	id = dax_read_lock();



	da = dax_direct_access(wc->ssd_dev->dax_dev, 0, p, &wc->memory_map, &pfn);

	da = dax_direct_access(wc->ssd_dev->dax_dev, offset, p, &wc->memory_map, &pfn);

	if (da < 0) {

		wc->memory_map = NULL;

		r = da;
@@ -266,7 +274,7 @@ static int persistent_memory_claim(struct dm_writecache *wc) 
		i = 0;

		do {

			long daa;

			daa = dax_direct_access(wc->ssd_dev->dax_dev, i, p - i,

			daa = dax_direct_access(wc->ssd_dev->dax_dev, offset + i, p - i,

						NULL, &pfn);

			if (daa <= 0) {

				r = daa ? daa : -EINVAL;