ext4: use sizeof(*ptr)

Replace the specification of data structures by pointer dereferences
as the parameter for the operator "sizeof" to make the corresponding size
determination a bit safer according to the Linux coding style convention.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>

fs/ext4/dir.c

@@ -411,7 +411,7 @@ static struct dir_private_info *ext4_htree_create_dir_info(struct file *filp,
 {
 	struct dir_private_info *p;
 
-	p = kzalloc(sizeof(struct dir_private_info), GFP_KERNEL);
+	p = kzalloc(sizeof(*p), GFP_KERNEL);
 	if (!p)
 		return NULL;
 	p->curr_hash = pos2maj_hash(filp, pos);