From cd77f4f8363602e5fbee481f38241110e65ff014 Mon Sep 17 00:00:00 2001 From: Liu Bo Date: Fri, 5 Jan 2018 12:51:14 -0700 Subject: [PATCH] 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: Liu Bo Reviewed-by: Josef Bacik Signed-off-by: David Sterba --- fs/btrfs/tests/extent-map-tests.c | 89 +++++++++++++++++++++++++++++++ 1 file changed, 89 insertions(+) diff --git a/fs/btrfs/tests/extent-map-tests.c b/fs/btrfs/tests/extent-map-tests.c index 16830bf88f46..70c993f01670 100644 --- a/fs/btrfs/tests/extent-map-tests.c +++ b/fs/btrfs/tests/extent-map-tests.c @@ -255,6 +255,94 @@ static void test_case_3(struct extent_map_tree *em_tree) __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() { struct extent_map_tree *em_tree; @@ -271,6 +359,7 @@ int btrfs_test_extent_map() test_case_1(em_tree); test_case_2(em_tree); test_case_3(em_tree); + test_case_4(em_tree); kfree(em_tree); return 0;