Re: [Drbd-dev] FLUSH/FUA documentation & code discrepancy

[Joseph Glanville <joseph.glanville@orionvm.com.au>]

On 13 September 2012 09:20, Tejun Heo <tj@kernel.org> wrote:
> On Thu, Sep 13, 2012 at 09:12:25AM +1000, Joseph Glanville wrote:
>> diff --git a/block/blk-core.c b/block/blk-core.c
>> index 4b4dbdf..68b5671 100644
>> --- a/block/blk-core.c
>> +++ b/block/blk-core.c
>> @@ -1809,6 +1809,9 @@ EXPORT_SYMBOL(generic_make_request);
>>   * uses that function to do most of the work. Both are fairly rough
>>   * interfaces; @bio must be presetup and ready for I/O.
>>   *
>> + * Ordering of requests is not guaranteed, callers should drain the queue
>> + * and issue a flush before submission of any dependent bios.
>
> I think using "requests" here is confusing given that struct request
> means something else in the block layer.  Also, the caller doesn't

Agreed, my bad.

> have to drain the whole queue but just the ones involved in the
> dependency and flush doesn't really matter here although mentioning
> that flush too doesn't have any ordering guarantee would be nice.

Will do.
Would you prefer it being added to the top of the file describing the
semantics or the blkdev_issue_flush function itself?

> Also, updating submit_bio() comment too would be nice - something
> simple about lack of ordering and then reference to
> generic_make_request().

Will do.

>
> Thanks.
>
> --
> tejun
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