btrfs: remove unnecessary local variables for checksum size

Remove local variable that is then used just once and replace it with
fs_info::csum_size.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index b2bb468..4e022ed 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -131,9 +131,8 @@ static int btrfs_decompress_bio(struct compressed_bio *cb);
 static inline int compressed_bio_size(struct btrfs_fs_info *fs_info,
 				      unsigned long disk_size)
 {
-	const u32 csum_size = fs_info->csum_size;
 	return sizeof(struct compressed_bio) +
-		(DIV_ROUND_UP(disk_size, fs_info->sectorsize)) * csum_size;
+		(DIV_ROUND_UP(disk_size, fs_info->sectorsize)) * fs_info->csum_size;
 }
 
 static int check_compressed_csum(struct btrfs_inode *inode, struct bio *bio,
@@ -627,7 +626,6 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 	struct extent_map *em;
 	blk_status_t ret = BLK_STS_RESOURCE;
 	int faili = 0;
-	const u32 csum_size = fs_info->csum_size;
 	u8 *sums;
 
 	em_tree = &BTRFS_I(inode)->extent_tree;
@@ -727,7 +725,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
 
 			nr_sectors = DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
 						  fs_info->sectorsize);
-			sums += csum_size * nr_sectors;
+			sums += fs_info->csum_size * nr_sectors;
 
 			ret = btrfs_map_bio(fs_info, comp_bio, mirror_num);
 			if (ret) {