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 <bo.li.liu@oracle.com> Reviewed-by: Josef Bacik <jbacik@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
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@ -255,6 +255,94 @@ static void test_case_3(struct extent_map_tree *em_tree)
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__test_case_3(em_tree, (12 * 1024ULL));
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}
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static void __test_case_4(struct extent_map_tree *em_tree, u64 start)
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{
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struct extent_map *em;
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u64 len = SZ_4K;
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int ret;
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em = alloc_extent_map();
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if (!em)
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/* Skip this test on error. */
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return;
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/* Add [0K, 8K) */
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em->start = 0;
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em->len = SZ_8K;
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em->block_start = 0;
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em->block_len = SZ_8K;
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ret = add_extent_mapping(em_tree, em, 0);
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ASSERT(ret == 0);
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free_extent_map(em);
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em = alloc_extent_map();
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if (!em)
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goto out;
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/* Add [8K, 24K) */
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em->start = SZ_8K;
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em->len = 24 * 1024ULL;
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em->block_start = SZ_16K; /* avoid merging */
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em->block_len = 24 * 1024ULL;
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ret = add_extent_mapping(em_tree, em, 0);
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ASSERT(ret == 0);
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free_extent_map(em);
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em = alloc_extent_map();
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if (!em)
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goto out;
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/* Add [0K, 32K) */
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em->start = 0;
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em->len = SZ_32K;
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em->block_start = 0;
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em->block_len = SZ_32K;
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ret = btrfs_add_extent_mapping(em_tree, &em, start, len);
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if (ret)
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test_msg("case4 [0x%llx 0x%llx): ret %d\n",
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start, len, ret);
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if (em &&
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(start < em->start || start + len > extent_map_end(em)))
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test_msg(
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"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",
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start, len, ret, em->start, em->len, em->block_start,
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em->block_len);
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free_extent_map(em);
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out:
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/* free memory */
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free_extent_map_tree(em_tree);
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}
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/*
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* Test scenario:
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*
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* Suppose that no extent map has been loaded into memory yet.
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* There is a file extent [0, 32K), two jobs are running concurrently
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* against it, t1 is doing dio write to [8K, 32K) and t2 is doing dio
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* read from [0, 4K) or [4K, 8K).
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*
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* t1 goes ahead of t2 and splits em [0, 32K) to em [0K, 8K) and [8K 32K).
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*
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* t1 t2
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* btrfs_get_blocks_direct() btrfs_get_blocks_direct()
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* -> btrfs_get_extent() -> btrfs_get_extent()
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* -> lookup_extent_mapping()
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* -> add_extent_mapping() -> lookup_extent_mapping()
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* # load [0, 32K)
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* -> btrfs_new_extent_direct()
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* -> btrfs_drop_extent_cache()
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* # split [0, 32K)
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* -> add_extent_mapping()
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* # add [8K, 32K)
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* -> add_extent_mapping()
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* # handle -EEXIST when adding
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* # [0, 32K)
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*/
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static void test_case_4(struct extent_map_tree *em_tree)
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{
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__test_case_4(em_tree, 0);
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__test_case_4(em_tree, SZ_4K);
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}
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int btrfs_test_extent_map()
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{
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struct extent_map_tree *em_tree;
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@ -271,6 +359,7 @@ int btrfs_test_extent_map()
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test_case_1(em_tree);
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test_case_2(em_tree);
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test_case_3(em_tree);
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test_case_4(em_tree);
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kfree(em_tree);
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return 0;
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