1 files changed, 20 insertions, 2 deletions

diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index 0d6ca723257f..4e414b06192e 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -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;
@@ -279,6 +287,8 @@ static int persistent_memory_claim(struct dm_writecache *wc)
 			while (daa-- && i < p) {
 				pages[i++] = pfn_t_to_page(pfn);
 				pfn.val++;
+				if (!(i & 15))
+					cond_resched();
 			}
 		} while (i < p);
 		wc->memory_map = vmap(pages, p, VM_MAP, PAGE_KERNEL);
@@ -805,6 +815,8 @@ static void writecache_discard(struct dm_writecache *wc, sector_t start, sector_
 				writecache_wait_for_ios(wc, WRITE);
 				discarded_something = true;
 			}
+			if (!writecache_entry_is_committed(wc, e))
+				wc->uncommitted_blocks--;
 			writecache_free_entry(wc, e);
 		}
 
@@ -2100,6 +2112,12 @@ invalid_optional:
 	}
 
 	if (WC_MODE_PMEM(wc)) {
+		if (!dax_synchronous(wc->ssd_dev->dax_dev)) {
+			r = -EOPNOTSUPP;
+			ti->error = "Asynchronous persistent memory not supported as pmem cache";
+			goto bad;
+		}
+
 		r = persistent_memory_claim(wc);
 		if (r) {
 			ti->error = "Unable to map persistent memory for cache";