btrfs: mark the len field in struct btrfs_ordered_sum as unsigned

len can't ever be negative, so mark it as an u32 instead of int.
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/file-item.c

@@ -561,7 +561,7 @@ int btrfs_lookup_csums_list(struct btrfs_root *root, u64 start, u64 end,
 			}
 
 			sums->bytenr = start;
-			sums->len = (int)size;
+			sums->len = size;
 
 			offset = bytes_to_csum_size(fs_info, start - key.offset);
 

fs/btrfs/ordered-data.h

@@ -20,7 +20,7 @@ struct btrfs_ordered_sum {
 	/*
 	 * this is the length in bytes covered by the sums array below.
 	 */
-	int len;
+	u32 len;
 	struct list_head list;
 	/* last field is a variable length array of csums */
 	u8 sums[];