btrfs: change btrfs_csum_final result param type to u8

csum member of struct btrfs_super_block has array type of u8. It makes
sense that function btrfs_csum_final should be also declared to accept
u8 *. I changed the declaration of method void btrfs_csum_final(u32 crc,
char *result); to void btrfs_csum_final(u32 crc, u8 *result);

Signed-off-by: Domagoj Tršan <domagoj.trsan@gmail.com>
[ changed cast to u8 at several call sites ]
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/compression.c

@@ -120,7 +120,7 @@ static int check_compressed_csum(struct inode *inode,
 
 		kaddr = kmap_atomic(page);
 		csum = btrfs_csum_data(kaddr, csum, PAGE_SIZE);
-		btrfs_csum_final(csum, (char *)&csum);
+		btrfs_csum_final(csum, (u8 *)&csum);
 		kunmap_atomic(kaddr);
 
 		if (csum != *cb_sum) {

fs/btrfs/disk-io.c

@@ -271,7 +271,7 @@ u32 btrfs_csum_data(char *data, u32 seed, size_t len)
 	return btrfs_crc32c(seed, data, len);
 }
 
-void btrfs_csum_final(u32 crc, char *result)
+void btrfs_csum_final(u32 crc, u8 *result)
 {
 	put_unaligned_le32(~crc, result);
 }

fs/btrfs/disk-io.h

@@ -119,7 +119,7 @@ int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid,
 			  int atomic);
 int btrfs_read_buffer(struct extent_buffer *buf, u64 parent_transid);
 u32 btrfs_csum_data(char *data, u32 seed, size_t len);
-void btrfs_csum_final(u32 crc, char *result);
+void btrfs_csum_final(u32 crc, u8 *result);
 int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
 			enum btrfs_wq_endio_type metadata);
 int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode,

fs/btrfs/free-space-cache.c

@@ -476,7 +476,7 @@ static void io_ctl_set_crc(struct btrfs_io_ctl *io_ctl, int index)
 
 	crc = btrfs_csum_data(io_ctl->orig + offset, crc,
 			      PAGE_SIZE - offset);
-	btrfs_csum_final(crc, (char *)&crc);
+	btrfs_csum_final(crc, (u8 *)&crc);
 	io_ctl_unmap_page(io_ctl);
 	tmp = page_address(io_ctl->pages[0]);
 	tmp += index;
@@ -504,7 +504,7 @@ static int io_ctl_check_crc(struct btrfs_io_ctl *io_ctl, int index)
 	io_ctl_map_page(io_ctl, 0);
 	crc = btrfs_csum_data(io_ctl->orig + offset, crc,
 			      PAGE_SIZE - offset);
-	btrfs_csum_final(crc, (char *)&crc);
+	btrfs_csum_final(crc, (u8 *)&crc);
 	if (val != crc) {
 		btrfs_err_rl(io_ctl->root->fs_info,
 			"csum mismatch on free space cache");

fs/btrfs/inode.c

@@ -3102,7 +3102,7 @@ static int __readpage_endio_check(struct inode *inode,
 
 	kaddr = kmap_atomic(page);
 	csum = btrfs_csum_data(kaddr + pgoff, csum,  len);
-	btrfs_csum_final(csum, (char *)&csum);
+	btrfs_csum_final(csum, (u8 *)&csum);
 	if (csum != csum_expected)
 		goto zeroit;