Re: [PATCH] btrfs: Annotate structs with __counted_by()

[Thorsten Blum]

On 12. Aug 2024, at 12:54, Johannes Thumshirn <Johannes.Thumshirn@xxxxxxx> wrote:
> On 12.08.24 12:37, Thorsten Blum wrote:
>> Add the __counted_by compiler attribute to the flexible array member
>> stripes to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and
>> CONFIG_FORTIFY_SOURCE.
>> 
>> Signed-off-by: Thorsten Blum <thorsten.blum@xxxxxxxxxx>
>> ---
>>  fs/btrfs/volumes.h | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>> 
>> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
>> index 37a09ebb34dd..f28fa318036b 100644
>> --- a/fs/btrfs/volumes.h
>> +++ b/fs/btrfs/volumes.h
>> @@ -551,7 +551,7 @@ struct btrfs_io_context {
>>   * stripes[data_stripes + 1]: The Q stripe (only for RAID6).
>>   */
>>   u64 full_stripe_logical;
>> - struct btrfs_io_stripe stripes[];
>> + struct btrfs_io_stripe stripes[] __counted_by(num_stripes);
>>  };
>> 
>>  struct btrfs_device_info {
>> @@ -591,7 +591,7 @@ struct btrfs_chunk_map {
>>   int io_width;
>>   int num_stripes;
>>   int sub_stripes;
>> - struct btrfs_io_stripe stripes[];
>> + struct btrfs_io_stripe stripes[] __counted_by(num_stripes);
>>  };
>> 
>>  #define btrfs_chunk_map_size(n) (sizeof(struct btrfs_chunk_map) + \
> 
> Looks good to me,
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
> 
> Out of curiosity, have you encountered any issues with this patch applied?

I only compile-tested it.