btrfs: tests: add a test for btrfs_add_extent_mapping

This helper is different from the normal add_extent_mapping in that it
will stuff an em into a gap that exists between overlapping em's in the
tree.  It appeared there was a bug so I wrote a self test to validate it
did the correct thing when it worked with two side by side ems.
Thankfully it is correct, but more testing is better.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/tests/extent-map-tests.c b/fs/btrfs/tests/extent-map-tests.c
index cf85c7795686f26ef6d5ec4b11e191876b877726..31de4cd0666f1c2c4e25f1e4f0e465dbece101c4 100644 (file)
--- a/fs/btrfs/tests/extent-map-tests.c
+++ b/fs/btrfs/tests/extent-map-tests.c
@@ -655,6 +655,59 @@ out:
        return ret;
 }
 
+/*
+ * Test the btrfs_add_extent_mapping helper which will attempt to create an em
+ * for areas between two existing ems.  Validate it doesn't do this when there
+ * are two unmerged em's side by side.
+ */
+static int test_case_6(struct btrfs_fs_info *fs_info, struct extent_map_tree *em_tree)
+{
+       struct extent_map *em = NULL;
+       int ret;
+
+       ret = add_compressed_extent(em_tree, 0, SZ_4K, 0);
+       if (ret)
+               goto out;
+
+       ret = add_compressed_extent(em_tree, SZ_4K, SZ_4K, 0);
+       if (ret)
+               goto out;
+
+       em = alloc_extent_map();
+       if (!em) {
+               test_std_err(TEST_ALLOC_EXTENT_MAP);
+               return -ENOMEM;
+       }
+
+       em->start = SZ_4K;
+       em->len = SZ_4K;
+       em->block_start = SZ_16K;
+       em->block_len = SZ_16K;
+       write_lock(&em_tree->lock);
+       ret = btrfs_add_extent_mapping(fs_info, em_tree, &em, 0, SZ_8K);
+       write_unlock(&em_tree->lock);
+
+       if (ret != 0) {
+               test_err("got an error when adding our em: %d", ret);
+               goto out;
+       }
+
+       ret = -EINVAL;
+       if (em->start != 0) {
+               test_err("unexpected em->start at %llu, wanted 0", em->start);
+               goto out;
+       }
+       if (em->len != SZ_4K) {
+               test_err("unexpected em->len %llu, expected 4K", em->len);
+               goto out;
+       }
+       ret = 0;
+out:
+       free_extent_map(em);
+       free_extent_map_tree(em_tree);
+       return ret;
+}
+
 struct rmap_test_vector {
        u64 raid_type;
        u64 physical_start;
@@ -835,6 +888,9 @@ int btrfs_test_extent_map(void)
        if (ret)
                goto out;
        ret = test_case_5();
+       if (ret)
+               goto out;
+       ret = test_case_6(fs_info, em_tree);
        if (ret)
                goto out;