Re: [PATCH 3/8] iomap: treat a write through cache the same as FUA

Jens Axboe
2023-07-21T14:04:24Z

On 7/21/23 12:15?AM, Christoph Hellwig wrote:
> On Thu, Jul 20, 2023 at 12:13:05PM -0600, Jens Axboe wrote:
>> Whether we have a write back cache and are using FUA or don't have
>> a write back cache at all is the same situation. Treat them the same.
>>
>> This makes the IOMAP_DIO_WRITE_FUA name a bit misleading, as we have
>> two cases that provide stable writes:
>>
>> 1) Volatile write cache with FUA writes
>> 2) Normal write without a volatile write cache
>>
>> Rename that flag to IOMAP_DIO_STABLE_WRITE to make that clearer, and
>> update some of the FUA comments as well.
>
> I would have preferred IOMAP_DIO_WRITE_THROUGH, STABLE_WRITES is a flag
> we use in file systems and the page cache for cases where the page
> can't be touched before writeback has completed, e.g.
> QUEUE_FLAG_STABLE_WRITES and SB_I_STABLE_WRITES.

Good point, it does confuse terminology with stable pages for writes.
I'll change it to WRITE_THROUGH, that is more descriptive for this case.

--
Jens Axboe