btrfs: use xxhash64 for checksumming

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>

fs/btrfs/Kconfig

diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index 38651fa..6d5a01c 100644
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -5,6 +5,7 @@
 	select CRYPTO
 	select CRYPTO_CRC32C
 	select LIBCRC32C
+	select CRYPTO_XXHASH
 	select ZLIB_INFLATE
 	select ZLIB_DEFLATE
 	select LZO_COMPRESS

fs/btrfs/ctree.h

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 139354d..c62729d 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -87,6 +87,7 @@ static const struct btrfs_csums {
 	const char	*name;
 } btrfs_csums[] = {
 	[BTRFS_CSUM_TYPE_CRC32] = { .size = 4, .name = "crc32c" },
+	[BTRFS_CSUM_TYPE_XXHASH] = { .size = 8, .name = "xxhash64" },
 };
 
 #define BTRFS_EMPTY_DIR_SIZE 0

fs/btrfs/disk-io.c

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 99dfd88..ac039a4 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -352,6 +352,7 @@ static bool btrfs_supported_super_csum(u16 csum_type)
 {
 	switch (csum_type) {
 	case BTRFS_CSUM_TYPE_CRC32:
+	case BTRFS_CSUM_TYPE_XXHASH:
 		return true;
 	default:
 		return false;

fs/btrfs/super.c

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 1b151af..60116d0 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2456,3 +2456,4 @@ module_exit(exit_btrfs_fs)
 
 MODULE_LICENSE("GPL");
 MODULE_SOFTDEP("pre: crc32c");
+MODULE_SOFTDEP("pre: xxhash64");

include/uapi/linux/btrfs_tree.h

diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index b65c7ee..ba2f125 100644
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -302,6 +302,7 @@
 /* csum types */
 enum btrfs_csum_type {
 	BTRFS_CSUM_TYPE_CRC32	= 0,
+	BTRFS_CSUM_TYPE_XXHASH	= 1,
 };
 
 /*