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: NEric Biggers <ebiggers@google.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/compression.c

@@ -194,11 +194,9 @@ static int check_compressed_csum(struct btrfs_inode *inode,
 	for (i = 0; i < cb->nr_pages; i++) {
 		page = cb->compressed_pages[i];
 
-		crypto_shash_init(shash);
 		kaddr = kmap_atomic(page);
-		crypto_shash_update(shash, kaddr, PAGE_SIZE);
+		crypto_shash_digest(shash, kaddr, PAGE_SIZE, csum);
 		kunmap_atomic(kaddr);
-		crypto_shash_final(shash, (u8 *)&csum);
 
 		if (memcmp(&csum, cb_sum, csum_size)) {
 			btrfs_print_data_csum_error(inode, disk_start,

fs/btrfs/disk-io.c

@@ -358,16 +358,14 @@ static int btrfs_check_super_csum(struct btrfs_fs_info *fs_info,
 	SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
 
 	shash->tfm = fs_info->csum_shash;
-	crypto_shash_init(shash);
 
 	/*
 	 * The super_block structure does not span the whole
 	 * BTRFS_SUPER_INFO_SIZE range, we expect that the unused space is
 	 * filled with zeros and is included in the checksum.
 	 */
-	crypto_shash_update(shash, raw_disk_sb + BTRFS_CSUM_SIZE,
-			    BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
-	crypto_shash_final(shash, result);
+	crypto_shash_digest(shash, raw_disk_sb + BTRFS_CSUM_SIZE,
+			    BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE, result);
 
 	if (memcmp(disk_sb->csum, result, btrfs_super_csum_size(disk_sb)))
 		return 1;
@@ -3504,10 +3502,9 @@ static int write_dev_supers(struct btrfs_device *device,
 
 		btrfs_set_super_bytenr(sb, bytenr);
 
-		crypto_shash_init(shash);
-		crypto_shash_update(shash, (const char *)sb + BTRFS_CSUM_SIZE,
-				    BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE);
-		crypto_shash_final(shash, sb->csum);
+		crypto_shash_digest(shash, (const char *)sb + BTRFS_CSUM_SIZE,
+				    BTRFS_SUPER_INFO_SIZE - BTRFS_CSUM_SIZE,
+				    sb->csum);
 
 		page = find_or_create_page(mapping, bytenr >> PAGE_SHIFT,
 					   GFP_NOFS);

fs/btrfs/file-item.c

@@ -601,13 +601,12 @@ blk_status_t btrfs_csum_one_bio(struct inode *inode, struct bio *bio,
 				index = 0;
 			}
 
-			crypto_shash_init(shash);
 			data = kmap_atomic(bvec.bv_page);
-			crypto_shash_update(shash, data + bvec.bv_offset
+			crypto_shash_digest(shash, data + bvec.bv_offset
 					    + (i * fs_info->sectorsize),
-					    fs_info->sectorsize);
+					    fs_info->sectorsize,
+					    sums->sums + index);
 			kunmap_atomic(data);
-			crypto_shash_final(shash, (char *)(sums->sums + index));
 			index += csum_size;
 			offset += fs_info->sectorsize;
 			this_sum_bytes += fs_info->sectorsize;

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;