btrfs: switch BTRFS_ORDERED_* to enums

We can use simple enum for values that are not part of on-disk format:
ordered extent flags.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ordered-data.h

@@ -37,26 +37,31 @@ struct btrfs_ordered_sum {
  * rbtree, just before waking any waiters.  It is used to indicate the
  * IO is done and any metadata is inserted into the tree.
  */
-#define BTRFS_ORDERED_IO_DONE 0 /* set when all the pages are written */
-
-#define BTRFS_ORDERED_COMPLETE 1 /* set when removed from the tree */
-
-#define BTRFS_ORDERED_NOCOW 2 /* set when we want to write in place */
-
-#define BTRFS_ORDERED_COMPRESSED 3 /* writing a zlib compressed extent */
-
-#define BTRFS_ORDERED_PREALLOC 4 /* set when writing to preallocated extent */
-
-#define BTRFS_ORDERED_DIRECT 5 /* set when we're doing DIO with this extent */
-
-#define BTRFS_ORDERED_IOERR 6 /* We had an io error when writing this out */
-
-#define BTRFS_ORDERED_UPDATED_ISIZE 7 /* indicates whether this ordered extent
-				       * has done its due diligence in updating
-				       * the isize. */
-#define BTRFS_ORDERED_TRUNCATED 8 /* Set when we have to truncate an extent */
-
-#define BTRFS_ORDERED_REGULAR 10 /* Regular IO for COW */
+enum {
+	/* set when all the pages are written */
+	BTRFS_ORDERED_IO_DONE,
+	/* set when removed from the tree */
+	BTRFS_ORDERED_COMPLETE,
+	/* set when we want to write in place */
+	BTRFS_ORDERED_NOCOW,
+	/* writing a zlib compressed extent */
+	BTRFS_ORDERED_COMPRESSED,
+	/* set when writing to preallocated extent */
+	BTRFS_ORDERED_PREALLOC,
+	/* set when we're doing DIO with this extent */
+	BTRFS_ORDERED_DIRECT,
+	/* We had an io error when writing this out */
+	BTRFS_ORDERED_IOERR,
+	/*
+	 * indicates whether this ordered extent has done its due diligence in
+	 * updating the isize
+	 */
+	BTRFS_ORDERED_UPDATED_ISIZE,
+	/* Set when we have to truncate an extent */
+	BTRFS_ORDERED_TRUNCATED,
+	/* Regular IO for COW */
+	BTRFS_ORDERED_REGULAR,
+};
 
 struct btrfs_ordered_extent {
 	/* logical offset in the file */