[PATCH RFC 01/16] block: Add atomic write operations to request_queue limits

[John Garry]

On 09/05/2023 01:19, Mike Snitzer wrote:
> On Wed, May 3, 2023 at 2:40 PM John Garry <john.g.garry at oracle.com> wrote:
>>
>> From: Himanshu Madhani <himanshu.madhani at oracle.com>
>>
>> Add the following limits:
>> - atomic_write_boundary
>> - atomic_write_max_bytes
>> - atomic_write_unit_max
>> - atomic_write_unit_min
>>
>> Signed-off-by: Himanshu Madhani <himanshu.madhani at oracle.com>
>> Signed-off-by: John Garry <john.g.garry at oracle.com>
>> ---
>>   Documentation/ABI/stable/sysfs-block | 42 +++++++++++++++++++++
>>   block/blk-settings.c                 | 56 ++++++++++++++++++++++++++++
>>   block/blk-sysfs.c                    | 33 ++++++++++++++++
>>   include/linux/blkdev.h               | 23 ++++++++++++
>>   4 files changed, 154 insertions(+)
>>
> 
> ...
> 
>> diff --git a/block/blk-settings.c b/block/blk-settings.c
>> index 896b4654ab00..e21731715a12 100644
>> --- a/block/blk-settings.c
>> +++ b/block/blk-settings.c
>> @@ -59,6 +59,9 @@ void blk_set_default_limits(struct queue_limits *lim)
>>          lim->zoned = BLK_ZONED_NONE;
>>          lim->zone_write_granularity = 0;
>>          lim->dma_alignment = 511;
>> +       lim->atomic_write_unit_min = lim->atomic_write_unit_max = 1;
>> +       lim->atomic_write_max_bytes = 512;
>> +       lim->atomic_write_boundary = 0;
>>   }
> 
> Not seeing required changes to blk_set_stacking_limits() nor blk_stack_limits().
> 
> Sorry to remind you of DM and MD limits stacking requirements. ;)
> 

Hi Mike,

Sorry for the slow response.

The idea is that initially we would not be adding stacked device 
support, so we can leave atomic defaults as min unit we always consider 
atomic, i.e. logical block size/fixed 512B sector size.

Thanks,
John