Re: [PATCH 3/4] btrfs: add a self test for btrfs_add_extent_mapping

[Filipe Manana <fdmanana@kernel.org>]

On Thu, Aug 17, 2023 at 04:57:32PM -0400, Josef Bacik wrote:
> 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.
> 
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>

Reviewed-by: Filipe Manana <fdmanana@suse.com>

Looks good, thanks.

> ---
>  fs/btrfs/tests/extent-map-tests.c | 57 +++++++++++++++++++++++++++++++
>  1 file changed, 57 insertions(+)
> 
> diff --git a/fs/btrfs/tests/extent-map-tests.c b/fs/btrfs/tests/extent-map-tests.c
> index d5f5e48ab55c..18ab03f0d029 100644
> --- a/fs/btrfs/tests/extent-map-tests.c
> +++ b/fs/btrfs/tests/extent-map-tests.c
> @@ -656,6 +656,60 @@ static int test_case_5(void)
>  	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;
> @@ -836,6 +890,9 @@ 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;
>  
> -- 
> 2.26.3
>