btrfs: use enum for extent type defines

Use enum to replace macro definitions of extent types.
Signed-off-by: NChengguang Xu <cgxu519@mykernel.net>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/tree-checker.c

@@ -221,11 +221,11 @@ static int check_extent_data_item(struct extent_buffer *leaf,
 
 	fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item);
 
-	if (btrfs_file_extent_type(leaf, fi) > BTRFS_FILE_EXTENT_TYPES) {
+	if (btrfs_file_extent_type(leaf, fi) >= BTRFS_NR_FILE_EXTENT_TYPES) {
 		file_extent_err(leaf, slot,
 		"invalid type for file extent, have %u expect range [0, %u]",
 			btrfs_file_extent_type(leaf, fi),
-			BTRFS_FILE_EXTENT_TYPES);
+			BTRFS_NR_FILE_EXTENT_TYPES - 1);
 		return -EUCLEAN;
 	}
 

include/uapi/linux/btrfs_tree.h

@@ -737,10 +737,12 @@ struct btrfs_balance_item {
 	__le64 unused[4];
 } __attribute__ ((__packed__));
 
-#define BTRFS_FILE_EXTENT_INLINE 0
-#define BTRFS_FILE_EXTENT_REG 1
-#define BTRFS_FILE_EXTENT_PREALLOC 2
-#define BTRFS_FILE_EXTENT_TYPES	2
+enum {
+	BTRFS_FILE_EXTENT_INLINE   = 0,
+	BTRFS_FILE_EXTENT_REG      = 1,
+	BTRFS_FILE_EXTENT_PREALLOC = 2,
+	BTRFS_NR_FILE_EXTENT_TYPES = 3,
+};
 
 struct btrfs_file_extent_item {
 	/*