ext4: remove unused variable from ext4_ext_in_cache()

Signed-off-by: "Theodore Ts'o" <[e-mail]>
Signed-off-by: Zhi Yong Wu <[e-mail]>
Reviewed-by: Zheng Liu <[e-mail]>

fs/ext4/extents.c

···
 		  struct ext4_extent *ex)
 {
 	struct ext4_ext_cache *cex;
-	struct ext4_sb_info *sbi;
 	int ret = 0;
 
 	/*
···
 	 */
 	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
 	cex = &EXT4_I(inode)->i_cached_extent;
-	sbi = EXT4_SB(inode->i_sb);
 
 	/* has cache valid data? */
 	if (cex->ec_len == 0)