FAILED: patch "[PATCH] Btrfs: fix unexpected cow in run_delalloc_nocow" failed to apply to 4.4-stable tree

index 6504e63b2317..491a7397f6fa 100644
@@ -1256,6 +1256,8 @@ static noinline int csum_exist_in_range(struct btrfs_fs_info *fs_info,
 		list_del(&sums->list);
 		kfree(sums);
 	}
+	if (ret < 0)
+		return ret;
 	return 1;
 }
 

@@ -1388,10 +1390,23 @@ static noinline int run_delalloc_nocow(struct inode *inode,
 				goto out_check;
 			if (btrfs_extent_readonly(fs_info, disk_bytenr))
 				goto out_check;
-			if (btrfs_cross_ref_exist(root, ino,
-						  found_key.offset -
-						  extent_offset, disk_bytenr))
+			ret = btrfs_cross_ref_exist(root, ino,
+						    found_key.offset -
+						    extent_offset, disk_bytenr);
+			if (ret) {
+				/*
+				 * ret could be -EIO if the above fails to read
+				 * metadata.
+				 */
+				if (ret < 0) {
+					if (cow_start != (u64)-1)
+						cur_offset = cow_start;
+					goto error;
+				}
+
+				WARN_ON_ONCE(nolock);
 				goto out_check;
+			}
 			disk_bytenr += extent_offset;
 			disk_bytenr += cur_offset - found_key.offset;
 			num_bytes = min(end + 1, extent_end) - cur_offset;

@@ -1409,10 +1424,22 @@ static noinline int run_delalloc_nocow(struct inode *inode,
 			 * this ensure that csum for a given extent are
 			 * either valid or do not exist.
 			 */
-			if (csum_exist_in_range(fs_info, disk_bytenr,
-						num_bytes)) {
+			ret = csum_exist_in_range(fs_info, disk_bytenr,
+						  num_bytes);
+			if (ret) {
 				if (!nolock)
 					btrfs_end_write_no_snapshotting(root);
+
+				/*
+				 * ret could be -EIO if the above fails to read
+				 * metadata.
+				 */
+				if (ret < 0) {
+					if (cow_start != (u64)-1)
+						cur_offset = cow_start;
+					goto error;
+				}
+				WARN_ON_ONCE(nolock);
 				goto out_check;
 			}
 			if (!btrfs_inc_nocow_writers(fs_info, disk_bytenr)) {

index 1f01a8172308..b895be3d4311 100644
@@ -1202,6 +1202,8 @@ static noinline int csum_exist_in_range(struct btrfs_root *root,
 		list_del(&sums->list);
 		kfree(sums);
 	}
+	if (ret < 0)
+		return ret;
 	return 1;
 }
 

@@ -1351,10 +1353,23 @@ next_slot:
 				goto out_check;
 			if (btrfs_extent_readonly(root, disk_bytenr))
 				goto out_check;
-			if (btrfs_cross_ref_exist(trans, root, ino,
+			ret = btrfs_cross_ref_exist(trans, root, ino,
 						  found_key.offset -
-						  extent_offset, disk_bytenr))
+						  extent_offset, disk_bytenr);
+			if (ret) {
+				/*
+				 * ret could be -EIO if the above fails to read
+				 * metadata.
+				 */
+				if (ret < 0) {
+					if (cow_start != (u64)-1)
+						cur_offset = cow_start;
+					goto error;
+				}
+
+				WARN_ON_ONCE(nolock);
 				goto out_check;
+			}
 			disk_bytenr += extent_offset;
 			disk_bytenr += cur_offset - found_key.offset;
 			num_bytes = min(end + 1, extent_end) - cur_offset;

@@ -1372,8 +1387,20 @@ next_slot:
 			 * this ensure that csum for a given extent are
 			 * either valid or do not exist.
 			 */
-			if (csum_exist_in_range(root, disk_bytenr, num_bytes))
+			ret = csum_exist_in_range(root, disk_bytenr, num_bytes);
+			if (ret) {
+				/*
+				 * ret could be -EIO if the above fails to read
+				 * metadata.
+				 */
+				if (ret < 0) {
+					if (cow_start != (u64)-1)
+						cur_offset = cow_start;
+					goto error;
+				}
+				WARN_ON_ONCE(nolock);
 				goto out_check;
+			}
 			nocow = 1;
 		} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
 			extent_end = found_key.offset +