btrfs: use u8 for raid_array members

The raid_attr table is now 7 * 56 = 392 bytes long, consisting of just
small numbers so we don't have to use ints. New size is 7 * 32 = 224,
saving 3 cachelines.
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -3704,7 +3704,7 @@ int btrfs_get_num_tolerated_disk_barrier_failures(u64 flags)
 
 	if ((flags & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0 ||
 	    (flags & BTRFS_AVAIL_ALLOC_BIT_SINGLE))
-		min_tolerated = min(min_tolerated,
+		min_tolerated = min_t(int, min_tolerated,
 				    btrfs_raid_array[BTRFS_RAID_SINGLE].
 				    tolerated_failures);
 
@@ -3713,7 +3713,7 @@ int btrfs_get_num_tolerated_disk_barrier_failures(u64 flags)
 			continue;
 		if (!(flags & btrfs_raid_array[raid_type].bg_flag))
 			continue;
-		min_tolerated = min(min_tolerated,
+		min_tolerated = min_t(int, min_tolerated,
 				    btrfs_raid_array[raid_type].
 				    tolerated_failures);
 	}

fs/btrfs/volumes.h

@@ -336,16 +336,16 @@ struct btrfs_device_info {
 };
 
 struct btrfs_raid_attr {
-	int sub_stripes;	/* sub_stripes info for map */
-	int dev_stripes;	/* stripes per dev */
-	int devs_max;		/* max devs to use */
-	int devs_min;		/* min devs needed */
-	int tolerated_failures; /* max tolerated fail devs */
-	int devs_increment;	/* ndevs has to be a multiple of this */
-	int ncopies;		/* how many copies to data has */
-	int nparity;		/* number of stripes worth of bytes to store
+	u8 sub_stripes;		/* sub_stripes info for map */
+	u8 dev_stripes;		/* stripes per dev */
+	u8 devs_max;		/* max devs to use */
+	u8 devs_min;		/* min devs needed */
+	u8 tolerated_failures;	/* max tolerated fail devs */
+	u8 devs_increment;	/* ndevs has to be a multiple of this */
+	u8 ncopies;		/* how many copies to data has */
+	u8 nparity;		/* number of stripes worth of bytes to store
 				 * parity information */
-	int mindev_error;	/* error code if min devs requisite is unmet */
+	u8 mindev_error;	/* error code if min devs requisite is unmet */
 	const char raid_name[8]; /* name of the raid */
 	u64 bg_flag;		/* block group flag of the raid */
 };