On 05/22/2018 10:32 AM, Jens Axboe wrote:
> On 5/22/18 9:07 AM, adam.manzanares@xxxxxxx wrote:
>> From: Adam Manzanares <adam.manzanares@xxxxxxx>
>>
>> In order to avoid kiocb bloat for per command iopriority support, rw_hint
>> is converted from enum to a u16. Added a guard around ki_hint assignment.
>>
>> Signed-off-by: Adam Manzanares <adam.manzanares@xxxxxxx>
>> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
>> ---
>> include/linux/fs.h | 13 +++++++++++--
>> 1 file changed, 11 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index 7f07977bdfd7..50de40dbbb85 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -284,6 +284,8 @@ enum rw_hint {
>> WRITE_LIFE_EXTREME = RWH_WRITE_LIFE_EXTREME,
>> };
>>
>> +#define MAX_KI_HINT ((1 << 16) - 1) /* ki_hint type is u16 */
>
> Instead of having to do this and now rely on those now being synced,
> how about something like the below.
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 760d8da1b6c7..070438d0b62d 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -299,7 +299,7 @@ struct kiocb {
> void (*ki_complete)(struct kiocb *iocb, long ret, long ret2);
> void *private;
> int ki_flags;
> - enum rw_hint ki_hint;
> + u16 ki_hint;
> } __randomize_layout;
>
> static inline bool is_sync_kiocb(struct kiocb *kiocb)
> @@ -1927,12 +1927,22 @@ static inline enum rw_hint file_write_hint(struct file *file)
>
> static inline int iocb_flags(struct file *file);
>
> +static inline u16 ki_hint_validate(enum rw_hint hint)
> +{
> + typeof(((struct kiocb *)0)->ki_hint) max_hint = -1;
This looks complex to me. Would force a reader to lookback at what
datatype ki_hint is. I'd prefer to declare it as u16 max_hint = -1, or
even the previous #define MAX_KI_HINT format is easier to read. Just a
program reading style you are comfortable with though.
--
Goldwyn
