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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: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Liu Bo 2018-01-05 12:51:14 -07:00 committed by David Sterba
parent fd87526fad
commit cd77f4f836
1 changed files with 89 additions and 0 deletions
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89
fs/btrfs/tests/extent-map-tests.c
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@ -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;