Re: [PATCH v2] fs: Add aio iopriority support for block_dev

[Adam Manzanares <Adam.Manzanares@wdc.com>]

On 5/3/18 11:33 AM, Matthew Wilcox wrote:
> On Thu, May 03, 2018 at 11:21:14AM -0700, adam.manzanares@wdc.com wrote:
>> If we want to avoid bloating struct kiocb, I suggest we turn the private field
>> into a union of the private and ki_ioprio field. It seems like the users of
>> the private field all use it at a point where we can yank the priority from
>> the kiocb before the private field is used. Comments and suggestions welcome.
> 
> Or we could just make ki_hint a u8 or u16 ... seems unlikely we'll need
> 32 bits of ki_hint.  (currently defined values are 1-5)

I like the approach of using a u16 for the ki_hint. I'll update and 
resubmit.

>> @@ -300,6 +301,7 @@ struct kiocb {
>>   	void			*private;
>>   	int			ki_flags;
>>   	enum rw_hint		ki_hint;
>> +	u16			ki_ioprio; /* See linux/ioprio.h */
>>   } __randomize_layout;
>>   
>>   static inline bool is_sync_kiocb(struct kiocb *kiocb)