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authorLiu Bo <bo.li.liu@oracle.com>2018-01-05 20:51:14 +0100
committerDavid Sterba <dsterba@suse.com>2018-01-22 16:08:22 +0100
commitcd77f4f8363602e5fbee481f38241110e65ff014 (patch)
tree9a5d1e3f5ab4682253f7abf5a0c69417f28ab4ef /fs/btrfs
parentBtrfs: extent map selftest: buffered write vs dio read (diff)
downloadlinux-cd77f4f8363602e5fbee481f38241110e65ff014.tar.xz
linux-cd77f4f8363602e5fbee481f38241110e65ff014.zip
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>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/tests/extent-map-tests.c89
1 files changed, 89 insertions, 0 deletions
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;