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Commit cd77f4f8 authored by Liu Bo's avatar Liu Bo Committed by David Sterba
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Btrfs: extent map selftest: dio write vs dio read 



This test case simulates the racy situation of dio write vs dio read,
and see if btrfs_get_extent() would return -EEXIST.

Signed-off-by: default avatarLiu Bo <bo.li.liu@oracle.com>
Reviewed-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent fd87526f

fs/btrfs/tests/extent-map-tests.c

+89 −0
Original line number Original line Diff line number Diff line
@@ -255,6 +255,94 @@ static void test_case_3(struct extent_map_tree *em_tree) 
	__test_case_3(em_tree, (12 * 1024ULL));

	__test_case_3(em_tree, (12 * 1024ULL));

}

}





static void __test_case_4(struct extent_map_tree *em_tree, u64 start)

{

	struct extent_map *em;

	u64 len = SZ_4K;

	int ret;



	em = alloc_extent_map();

	if (!em)

		/* Skip this test on error. */

		return;



	/* Add [0K, 8K) */

	em->start = 0;

	em->len = SZ_8K;

	em->block_start = 0;

	em->block_len = SZ_8K;

	ret = add_extent_mapping(em_tree, em, 0);

	ASSERT(ret == 0);

	free_extent_map(em);



	em = alloc_extent_map();

	if (!em)

		goto out;



	/* Add [8K, 24K) */

	em->start = SZ_8K;

	em->len = 24 * 1024ULL;

	em->block_start = SZ_16K; /* avoid merging */

	em->block_len = 24 * 1024ULL;

	ret = add_extent_mapping(em_tree, em, 0);

	ASSERT(ret == 0);

	free_extent_map(em);



	em = alloc_extent_map();

	if (!em)

		goto out;

	/* Add [0K, 32K) */

	em->start = 0;

	em->len = SZ_32K;

	em->block_start = 0;

	em->block_len = SZ_32K;

	ret = btrfs_add_extent_mapping(em_tree, &em, start, len);

	if (ret)

		test_msg("case4 [0x%llx 0x%llx): ret %d\n",

			 start, len, ret);

	if (em &&

	    (start < em->start || start + len > extent_map_end(em)))

		test_msg(

"case4 [0x%llx 0x%llx): ret %d, added wrong em (start 0x%llx len 0x%llx block_start 0x%llx block_len 0x%llx)\n",

			 start, len, ret, em->start, em->len, em->block_start,

			 em->block_len);

	free_extent_map(em);

out:

	/* free memory */

	free_extent_map_tree(em_tree);

}



/*

 * Test scenario:

 *

 * Suppose that no extent map has been loaded into memory yet.

 * There is a file extent [0, 32K), two jobs are running concurrently

 * against it, t1 is doing dio write to [8K, 32K) and t2 is doing dio

 * read from [0, 4K) or [4K, 8K).

 *

 * t1 goes ahead of t2 and splits em [0, 32K) to em [0K, 8K) and [8K 32K).

 *

 *         t1                                t2

 *  btrfs_get_blocks_direct()	       btrfs_get_blocks_direct()

 *   -> btrfs_get_extent()              -> btrfs_get_extent()

 *       -> lookup_extent_mapping()

 *       -> add_extent_mapping()            -> lookup_extent_mapping()

 *          # load [0, 32K)

 *   -> btrfs_new_extent_direct()

 *       -> btrfs_drop_extent_cache()

 *          # split [0, 32K)

 *       -> add_extent_mapping()

 *          # add [8K, 32K)

 *                                          -> add_extent_mapping()

 *                                             # handle -EEXIST when adding

 *                                             # [0, 32K)

 */

static void test_case_4(struct extent_map_tree *em_tree)

{

	__test_case_4(em_tree, 0);

	__test_case_4(em_tree, SZ_4K);

}



int btrfs_test_extent_map()

int btrfs_test_extent_map()

{

{

	struct extent_map_tree *em_tree;

	struct extent_map_tree *em_tree;
@@ -271,6 +359,7 @@ int btrfs_test_extent_map() 
	test_case_1(em_tree);

	test_case_1(em_tree);

	test_case_2(em_tree);

	test_case_2(em_tree);

	test_case_3(em_tree);

	test_case_3(em_tree);

	test_case_4(em_tree);





	kfree(em_tree);

	kfree(em_tree);

	return 0;

	return 0;