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Btrfs: extent map selftest: buffered write vs dio read

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This test case simulates the racy situation of buffered 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 12:51:13 -07:00 committed by David Sterba
parent 72b28077a2
commit fd87526fad
1 changed files with 74 additions and 0 deletions
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74
fs/btrfs/tests/extent-map-tests.c
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@ -182,6 +182,79 @@ out:
free_extent_map_tree(em_tree);
}
static void __test_case_3(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 [4K, 8K) */
em->start = SZ_4K;
em->len = SZ_4K;
em->block_start = SZ_4K;
em->block_len = SZ_4K;
ret = add_extent_mapping(em_tree, em, 0);
ASSERT(ret == 0);
free_extent_map(em);
em = alloc_extent_map();
if (!em)
goto out;
/* Add [0, 16K) */
em->start = 0;
em->len = SZ_16K;
em->block_start = 0;
em->block_len = SZ_16K;
ret = btrfs_add_extent_mapping(em_tree, &em, start, len);
if (ret)
test_msg("case3 [0x%llx 0x%llx): ret %d\n",
start, start + len, ret);
/*
* Since bytes within em are contiguous, em->block_start is identical to
* em->start.
*/
if (em &&
(start < em->start || start + len > extent_map_end(em) ||
em->start != em->block_start || em->len != em->block_len))
test_msg(
"case3 [0x%llx 0x%llx): ret %d em (start 0x%llx len 0x%llx block_start 0x%llx block_len 0x%llx)\n",
start, 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, 16K), two jobs are running concurrently
* against it, t1 is buffered writing to [4K, 8K) and t2 is doing dio
* read from [0, 4K) or [8K, 12K) or [12K, 16K).
*
* t1 goes ahead of t2 and adds em [4K, 8K) into tree.
*
* t1 t2
* cow_file_range() btrfs_get_extent()
* -> lookup_extent_mapping()
* -> add_extent_mapping()
* -> add_extent_mapping()
*/
static void test_case_3(struct extent_map_tree *em_tree)
{
__test_case_3(em_tree, 0);
__test_case_3(em_tree, SZ_8K);
__test_case_3(em_tree, (12 * 1024ULL));
}
int btrfs_test_extent_map()
{
struct extent_map_tree *em_tree;
@ -197,6 +270,7 @@ int btrfs_test_extent_map()
test_case_1(em_tree);
test_case_2(em_tree);
test_case_3(em_tree);
kfree(em_tree);
return 0;