Re: [PATCH 2/2] xfs: don't take addresses of packed xfs_rmap_key

Eric Sandeen
2020-01-29T18:10:37Z

On 1/29/20 11:56 AM, Darrick J. Wong wrote:
> On Wed, Jan 29, 2020 at 11:45:05AM -0600, Eric Sandeen wrote:
>> gcc now warns about taking an address of a packed structure member.
>>
>> This happens here because of how be32_add_cpu() works; just open-code
>> the modification using a temporary variable instead.
>>
>> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
>> ---
>>
>> diff --git a/fs/xfs/libxfs/xfs_rmap_btree.c b/fs/xfs/libxfs/xfs_rmap_btree.c
>> index fc78efa52c94..ad5ead62c992 100644
>> --- a/fs/xfs/libxfs/xfs_rmap_btree.c
>> +++ b/fs/xfs/libxfs/xfs_rmap_btree.c
>> @@ -182,12 +182,14 @@ xfs_rmapbt_init_high_key_from_rec(
>> union xfs_btree_rec *rec)
>> {
>> uint64_t off;
>> + xfs_agblock_t start;
>> int adj;
>>
>> adj = be32_to_cpu(rec->rmap.rm_blockcount) - 1;
>>
>> key->rmap.rm_startblock = rec->rmap.rm_startblock;
>
> I was gonna say to kill this statement since you set it again two lines
> later, but then spotted a bug two lines down...
>
>> - be32_add_cpu(&key->rmap.rm_startblock, adj);
>> + start = be32_to_cpu(rec->rmap.rm_startblock) - adj;
>> + rec->rmap.rm_startblock = cpu_to_be32(start);

/searches for that brown paper bag

thanks

-Eric