ext4: move checksum length calculation of inode bitmap into ext4_inode_bitmap_csum_[verify/set]() functions

There are some little improve:
1. remove repeat code to calculate checksum length of inode bitmap
2. remove unnecessary checksum length calculation if checksum is not
enabled.
3. use more efficient bit shift operation instead of div opreation.

Signed-off-by: Kemeng Shi <shikemeng@huaweicloud.com>
Link: https://patch.msgid.link/20240820132234.2759926-6-shikemeng@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Author: Kemeng Shi

fs/ext4/bitmap.c

@@ -18,15 +18,17 @@ unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
 
 int ext4_inode_bitmap_csum_verify(struct super_block *sb,
 				  struct ext4_group_desc *gdp,
-				  struct buffer_head *bh, int sz)
+				  struct buffer_head *bh)
 {
 	__u32 hi;
 	__u32 provided, calculated;
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	int sz;
 
 	if (!ext4_has_metadata_csum(sb))
 		return 1;
 
+	sz = EXT4_INODES_PER_GROUP(sb) >> 3;
 	provided = le16_to_cpu(gdp->bg_inode_bitmap_csum_lo);
 	calculated = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
 	if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END) {
@@ -40,14 +42,16 @@ int ext4_inode_bitmap_csum_verify(struct super_block *sb,
 
 void ext4_inode_bitmap_csum_set(struct super_block *sb,
 				struct ext4_group_desc *gdp,
-				struct buffer_head *bh, int sz)
+				struct buffer_head *bh)
 {
 	__u32 csum;
 	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	int sz;
 
 	if (!ext4_has_metadata_csum(sb))
 		return;
 
+	sz = EXT4_INODES_PER_GROUP(sb) >> 3;
 	csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)bh->b_data, sz);
 	gdp->bg_inode_bitmap_csum_lo = cpu_to_le16(csum & 0xFFFF);
 	if (sbi->s_desc_size >= EXT4_BG_INODE_BITMAP_CSUM_HI_END)

fs/ext4/ext4.h

@@ -2693,10 +2693,10 @@ struct mmpd_data {
 extern unsigned int ext4_count_free(char *bitmap, unsigned numchars);
 void ext4_inode_bitmap_csum_set(struct super_block *sb,
 				struct ext4_group_desc *gdp,
-				struct buffer_head *bh, int sz);
+				struct buffer_head *bh);
 int ext4_inode_bitmap_csum_verify(struct super_block *sb,
 				  struct ext4_group_desc *gdp,
-				  struct buffer_head *bh, int sz);
+				  struct buffer_head *bh);
 void ext4_block_bitmap_csum_set(struct super_block *sb,
 				struct ext4_group_desc *gdp,
 				struct buffer_head *bh);

fs/ext4/ialloc.c

@@ -98,8 +98,7 @@ static int ext4_validate_inode_bitmap(struct super_block *sb,
 	if (buffer_verified(bh))
 		goto verified;
 	blk = ext4_inode_bitmap(sb, desc);
-	if (!ext4_inode_bitmap_csum_verify(sb, desc, bh,
-					   EXT4_INODES_PER_GROUP(sb) / 8) ||
+	if (!ext4_inode_bitmap_csum_verify(sb, desc, bh) ||
 	    ext4_simulate_fail(sb, EXT4_SIM_IBITMAP_CRC)) {
 		ext4_unlock_group(sb, block_group);
 		ext4_error(sb, "Corrupt inode bitmap - block_group = %u, "
@@ -327,8 +326,7 @@ void ext4_free_inode(handle_t *handle, struct inode *inode)
 		if (percpu_counter_initialized(&sbi->s_dirs_counter))
 			percpu_counter_dec(&sbi->s_dirs_counter);
 	}
-	ext4_inode_bitmap_csum_set(sb, gdp, bitmap_bh,
-				   EXT4_INODES_PER_GROUP(sb) / 8);
+	ext4_inode_bitmap_csum_set(sb, gdp, bitmap_bh);
 	ext4_group_desc_csum_set(sb, block_group, gdp);
 	ext4_unlock_group(sb, block_group);
 
@@ -853,8 +851,7 @@ int ext4_mark_inode_used(struct super_block *sb, int ino)
 
 	ext4_free_inodes_set(sb, gdp, ext4_free_inodes_count(sb, gdp) - 1);
 	if (ext4_has_group_desc_csum(sb)) {
-		ext4_inode_bitmap_csum_set(sb, gdp, inode_bitmap_bh,
-					   EXT4_INODES_PER_GROUP(sb) / 8);
+		ext4_inode_bitmap_csum_set(sb, gdp, inode_bitmap_bh);
 		ext4_group_desc_csum_set(sb, group, gdp);
 	}
 
@@ -1225,8 +1222,7 @@ struct inode *__ext4_new_inode(struct mnt_idmap *idmap,
 		}
 	}
 	if (ext4_has_group_desc_csum(sb)) {
-		ext4_inode_bitmap_csum_set(sb, gdp, inode_bitmap_bh,
-					   EXT4_INODES_PER_GROUP(sb) / 8);
+		ext4_inode_bitmap_csum_set(sb, gdp, inode_bitmap_bh);
 		ext4_group_desc_csum_set(sb, group, gdp);
 	}
 	ext4_unlock_group(sb, group);

fs/ext4/resize.c

@@ -1319,8 +1319,7 @@ static int ext4_set_bitmap_checksums(struct super_block *sb,
 	bh = ext4_get_bitmap(sb, group_data->inode_bitmap);
 	if (!bh)
 		return -EIO;
-	ext4_inode_bitmap_csum_set(sb, gdp, bh,
-				   EXT4_INODES_PER_GROUP(sb) / 8);
+	ext4_inode_bitmap_csum_set(sb, gdp, bh);
 	brelse(bh);
 
 	bh = ext4_get_bitmap(sb, group_data->block_bitmap);