ext4: replace KUnit tests for memcmp() with KUNIT_ASSERT_MEMEQ()

Replace KUnit tests for memcmp() with KUNIT_ASSERT_MEMEQ() to improve
debugging that prints the hex dump of the buffers when the assertion fails,
whereas memcmp() only returns an integer difference.

Signed-off-by: Ryota Sakamoto <sakamo.ryota@gmail.com>
Link: https://patch.msgid.link/20260127-fix-fs_ext4-memcmp-v1-1-5c269ae906b6@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

Author: ryota-sakamoto

fs/ext4/mballoc-test.c

@@ -714,8 +714,7 @@ do_test_generate_buddy(struct kunit *test, struct super_block *sb, void *bitmap,
 	ext4_mb_generate_buddy_test(sb, ext4_buddy, bitmap, TEST_GOAL_GROUP,
 			       ext4_grp);
 
-	KUNIT_ASSERT_EQ(test, memcmp(mbt_buddy, ext4_buddy, sb->s_blocksize),
-			0);
+	KUNIT_ASSERT_MEMEQ(test, mbt_buddy, ext4_buddy, sb->s_blocksize);
 	mbt_validate_group_info(test, mbt_grp, ext4_grp);
 }
 
@@ -776,8 +775,7 @@ test_mb_mark_used_range(struct kunit *test, struct ext4_buddy *e4b,
 		grp->bb_counters[i] = 0;
 	ext4_mb_generate_buddy_test(sb, buddy, bitmap, 0, grp);
 
-	KUNIT_ASSERT_EQ(test, memcmp(buddy, e4b->bd_buddy, sb->s_blocksize),
-			0);
+	KUNIT_ASSERT_MEMEQ(test, buddy, e4b->bd_buddy, sb->s_blocksize);
 	mbt_validate_group_info(test, grp, e4b->bd_info);
 }
 
@@ -841,8 +839,7 @@ test_mb_free_blocks_range(struct kunit *test, struct ext4_buddy *e4b,
 		grp->bb_counters[i] = 0;
 	ext4_mb_generate_buddy_test(sb, buddy, bitmap, 0, grp);
 
-	KUNIT_ASSERT_EQ(test, memcmp(buddy, e4b->bd_buddy, sb->s_blocksize),
-			0);
+	KUNIT_ASSERT_MEMEQ(test, buddy, e4b->bd_buddy, sb->s_blocksize);
 	mbt_validate_group_info(test, grp, e4b->bd_info);
 
 }