btrfs: mirror_num should be int, not u64

My previous patch introduced some u64 for failed_mirror variables, this one
makes it consistent again.
Signed-off-by: NJan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: NChris Mason <chris.mason@oracle.com>

fs/btrfs/disk-io.c

@@ -620,7 +620,7 @@ static int btree_readpage_end_io_hook(struct page *page, u64 start, u64 end,
 
 static int btree_io_failed_hook(struct bio *failed_bio,
 			 struct page *page, u64 start, u64 end,
-			 u64 mirror_num, struct extent_state *state)
+			 int mirror_num, struct extent_state *state)
 {
 	struct extent_io_tree *tree;
 	unsigned long len;

fs/btrfs/extent_io.c

@@ -2285,8 +2285,8 @@ static void end_bio_extent_readpage(struct bio *bio, int err)
 				clean_io_failure(start, page);
 		}
 		if (!uptodate) {
-			u64 failed_mirror;
-			failed_mirror = (unsigned long)bio->bi_bdev;
+			int failed_mirror;
+			failed_mirror = (int)(unsigned long)bio->bi_bdev;
 			if (tree->ops && tree->ops->readpage_io_failed_hook)
 				ret = tree->ops->readpage_io_failed_hook(
 						bio, page, start, end,

fs/btrfs/extent_io.h

@@ -70,7 +70,7 @@ struct extent_io_ops {
 			      unsigned long bio_flags);
 	int (*readpage_io_hook)(struct page *page, u64 start, u64 end);
 	int (*readpage_io_failed_hook)(struct bio *bio, struct page *page,
-				       u64 start, u64 end, u64 failed_mirror,
+				       u64 start, u64 end, int failed_mirror,
 				       struct extent_state *state);
 	int (*writepage_io_failed_hook)(struct bio *bio, struct page *page,
 					u64 start, u64 end,