btrfs: use crypto_shash_digest() instead of open coding

Use crypto_shash_digest() instead of crypto_shash_init() +
crypto_shash_update() + crypto_shash_final().  This is more efficient.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 5d56708..cc94291 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2742,9 +2742,7 @@ static int check_data_csum(struct inode *inode, struct btrfs_io_bio *io_bio,
 	kaddr = kmap_atomic(page);
 	shash->tfm = fs_info->csum_shash;
 
-	crypto_shash_init(shash);
-	crypto_shash_update(shash, kaddr + pgoff, len);
-	crypto_shash_final(shash, csum);
+	crypto_shash_digest(shash, kaddr + pgoff, len, csum);
 
 	if (memcmp(csum, csum_expected, csum_size))
 		goto zeroit;