btrfs: switch btrfs_block_rsv::failfast to bool

Use simple bool type for the block reserve failfast status, there's
short to save space as there used to be int but there's no reason for
that.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/block-rsv.h

@@ -26,8 +26,8 @@ struct btrfs_block_rsv {
 	struct btrfs_space_info *space_info;
 	spinlock_t lock;
 	bool full;
+	bool failfast;
 	unsigned short type;
-	unsigned short failfast;
 
 	/*
 	 * Qgroup equivalent for @size @reserved

fs/btrfs/file.c

@@ -2736,7 +2736,7 @@ int btrfs_replace_file_extents(struct btrfs_inode *inode,
 		goto out;
 	}
 	rsv->size = btrfs_calc_insert_metadata_size(fs_info, 1);
-	rsv->failfast = 1;
+	rsv->failfast = true;
 
 	/*
 	 * 1 - update the inode

fs/btrfs/inode.c

@@ -5432,7 +5432,7 @@ void btrfs_evict_inode(struct inode *inode)
 	if (!rsv)
 		goto no_delete;
 	rsv->size = btrfs_calc_metadata_size(fs_info, 1);
-	rsv->failfast = 1;
+	rsv->failfast = true;
 
 	btrfs_i_size_write(BTRFS_I(inode), 0);
 
@@ -8686,7 +8686,7 @@ static int btrfs_truncate(struct inode *inode, bool skip_writeback)
 	if (!rsv)
 		return -ENOMEM;
 	rsv->size = min_size;
-	rsv->failfast = 1;
+	rsv->failfast = true;
 
 	/*
 	 * 1 for the truncate slack space