[lvc-project] [PATCH 1/1] dm-vdo: Refactor VDO_ASSERT usage in start_restoring_volume functions

[Matthew Sakai]

On 9/8/25 6:24 PM, Ivan Abramov wrote:
> There's an incorrect VDO_ASSERT macro usage in
> start_restoring volume_index() and start_restoring_volume_sub_index(),
> since assert's return value is not used anywhere.
> 
> Thus, use VDO_ASSERT_LOG_ONLY macro in such cases.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Signed-off-by: Ivan Abramov <i.abramov at mt-integration.ru>
> ---
>   drivers/md/dm-vdo/indexer/volume-index.c | 8 ++------
>   1 file changed, 2 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/md/dm-vdo/indexer/volume-index.c b/drivers/md/dm-vdo/indexer/volume-index.c
> index 12f954a0c532..99608f14400a 100644
> --- a/drivers/md/dm-vdo/indexer/volume-index.c
> +++ b/drivers/md/dm-vdo/indexer/volume-index.c
> @@ -832,11 +832,9 @@ static int start_restoring_volume_sub_index(struct volume_sub_index *sub_index,
>   		decode_u32_le(buffer, &offset, &header.first_list);
>   		decode_u32_le(buffer, &offset, &header.list_count);
>   
> -		result = VDO_ASSERT(offset == sizeof(buffer),
> +		VDO_ASSERT_LOG_ONLY(offset == sizeof(buffer),
>   				    "%zu bytes decoded of %zu expected", offset,
>   				    sizeof(buffer));
> -		if (result != VDO_SUCCESS)
> -			result = UDS_CORRUPT_DATA;

This is not a correct fix so we should not take this.

This assertion (and the one below) should only fail if the stored 
metadata has been corrupted, but in that case we definitely need to 
return the error and fail the load.

You are correct that we don't seem to use this result, but the correct 
fix is to return UDS_CORRUPT_DATA when this assertion fails.

Matt


>   		if (memcmp(header.magic, MAGIC_START_5, MAGIC_SIZE) != 0) {
>   			return vdo_log_warning_strerror(UDS_CORRUPT_DATA,
> @@ -924,11 +922,9 @@ static int start_restoring_volume_index(struct volume_index *volume_index,
>   		offset += MAGIC_SIZE;
>   		decode_u32_le(buffer, &offset, &header.sparse_sample_rate);
>   
> -		result = VDO_ASSERT(offset == sizeof(buffer),
> +		VDO_ASSERT_LOG_ONLY(offset == sizeof(buffer),
>   				    "%zu bytes decoded of %zu expected", offset,
>   				    sizeof(buffer));
> -		if (result != VDO_SUCCESS)
> -			result = UDS_CORRUPT_DATA;
>   
>   		if (memcmp(header.magic, MAGIC_START_6, MAGIC_SIZE) != 0)
>   			return vdo_log_warning_strerror(UDS_CORRUPT_DATA,