btrfs: add blake2b to checksumming algorithms

Add blake2b (with 256 bit digest) to the list of possible checksumming
algorithms used by BTRFS.
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/ctree.c

@@ -37,6 +37,8 @@ static const struct btrfs_csums {
 	[BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
 	[BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
 	[BTRFS_CSUM_TYPE_SHA256] = { .size = 32, .name = "sha256" },
+	[BTRFS_CSUM_TYPE_BLAKE2] = { .size = 32, .name = "blake2b",
+				     .driver = "blake2b-256" },
 };
 
 int btrfs_super_csum_size(const struct btrfs_super_block *s)

fs/btrfs/disk-io.c

@@ -354,6 +354,7 @@ static bool btrfs_supported_super_csum(u16 csum_type)
 	case BTRFS_CSUM_TYPE_CRC32:
 	case BTRFS_CSUM_TYPE_XXHASH:
 	case BTRFS_CSUM_TYPE_SHA256:
+	case BTRFS_CSUM_TYPE_BLAKE2:
 		return true;
 	default:
 		return false;

fs/btrfs/super.c

@@ -2464,3 +2464,4 @@ MODULE_LICENSE("GPL");
 MODULE_SOFTDEP("pre: crc32c");
 MODULE_SOFTDEP("pre: xxhash64");
 MODULE_SOFTDEP("pre: sha256");
+MODULE_SOFTDEP("pre: blake2b-256");

include/uapi/linux/btrfs_tree.h

@@ -304,6 +304,7 @@ enum btrfs_csum_type {
 	BTRFS_CSUM_TYPE_CRC32	= 0,
 	BTRFS_CSUM_TYPE_XXHASH	= 1,
 	BTRFS_CSUM_TYPE_SHA256	= 2,
+	BTRFS_CSUM_TYPE_BLAKE2	= 3,
 };
 
 /*