Re: [PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[Adam Manzanares]

On 5/22/18 9:30 AM, Jens Axboe wrote:
> On 5/22/18 10:24 AM, Goldwyn Rodrigues wrote:
>>
>>
>> On 05/22/2018 10:32 AM, Jens Axboe wrote:
>>> On 5/22/18 9:07 AM, adam.manzana...@wdc.com wrote:
 From: Adam Manzanares 

 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 
 Reviewed-by: Christoph Hellwig 
 ---
   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_hintki_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.
> 
> How is it complex? It's defining a type that'll be the same as ki_hint
> in the kiocb, which is _exactly_ what we care about. Any sort of other
> definition will rely on those two locations now being synced. The
> above will never break.
> 
> So I strongly disagree. The above will _never_ require the reader to
> figure out what the type is. Any other variant will _always_ require
> the reader to check if they are the same.
> 

I do think the previous code was a bit easier to parse at first glance, 
but that is outweighed by the fact that the validate function is now 
directly tied to the kiocb ki_hint type.

I also missed one spot where I should have used ki_hint_validate. Will 
resend soon.

Re: [PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[Adam Manzanares]

On 5/22/18 9:30 AM, Jens Axboe wrote:
> On 5/22/18 10:24 AM, Goldwyn Rodrigues wrote:
>>
>>
>> On 05/22/2018 10:32 AM, Jens Axboe wrote:
>>> On 5/22/18 9:07 AM, adam.manzana...@wdc.com wrote:
 From: Adam Manzanares 

 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 
 Reviewed-by: Christoph Hellwig 
 ---
   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_hintki_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.
> 
> How is it complex? It's defining a type that'll be the same as ki_hint
> in the kiocb, which is _exactly_ what we care about. Any sort of other
> definition will rely on those two locations now being synced. The
> above will never break.
> 
> So I strongly disagree. The above will _never_ require the reader to
> figure out what the type is. Any other variant will _always_ require
> the reader to check if they are the same.
> 

I do think the previous code was a bit easier to parse at first glance, 
but that is outweighed by the fact that the validate function is now 
directly tied to the kiocb ki_hint type.

I also missed one spot where I should have used ki_hint_validate. Will 
resend soon.

Re: [PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[Jens Axboe]

On 5/22/18 10:24 AM, Goldwyn Rodrigues wrote:
> 
> 
> On 05/22/2018 10:32 AM, Jens Axboe wrote:
>> On 5/22/18 9:07 AM, adam.manzana...@wdc.com wrote:
>>> From: Adam Manzanares 
>>>
>>> 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 
>>> Reviewed-by: Christoph Hellwig 
>>> ---
>>>  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_hintki_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.

How is it complex? It's defining a type that'll be the same as ki_hint
in the kiocb, which is _exactly_ what we care about. Any sort of other
definition will rely on those two locations now being synced. The
above will never break.

So I strongly disagree. The above will _never_ require the reader to
figure out what the type is. Any other variant will _always_ require
the reader to check if they are the same.

-- 
Jens Axboe

Re: [PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[Jens Axboe]

On 5/22/18 10:24 AM, Goldwyn Rodrigues wrote:
> 
> 
> On 05/22/2018 10:32 AM, Jens Axboe wrote:
>> On 5/22/18 9:07 AM, adam.manzana...@wdc.com wrote:
>>> From: Adam Manzanares 
>>>
>>> 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 
>>> Reviewed-by: Christoph Hellwig 
>>> ---
>>>  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_hintki_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.

How is it complex? It's defining a type that'll be the same as ki_hint
in the kiocb, which is _exactly_ what we care about. Any sort of other
definition will rely on those two locations now being synced. The
above will never break.

So I strongly disagree. The above will _never_ require the reader to
figure out what the type is. Any other variant will _always_ require
the reader to check if they are the same.

-- 
Jens Axboe

Re: [PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[Goldwyn Rodrigues]

On 05/22/2018 10:32 AM, Jens Axboe wrote:
> On 5/22/18 9:07 AM, adam.manzana...@wdc.com wrote:
>> From: Adam Manzanares 
>>
>> 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 
>> Reviewed-by: Christoph Hellwig 
>> ---
>>  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_hintki_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

Re: [PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[Goldwyn Rodrigues]

On 05/22/2018 10:32 AM, Jens Axboe wrote:
> On 5/22/18 9:07 AM, adam.manzana...@wdc.com wrote:
>> From: Adam Manzanares 
>>
>> 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 
>> Reviewed-by: Christoph Hellwig 
>> ---
>>  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_hintki_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

Re: [PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[Adam Manzanares]

On 5/22/18 8:32 AM, Jens Axboe wrote:
> On 5/22/18 9:07 AM, adam.manzana...@wdc.com wrote:
>> From: Adam Manzanares 
>>
>> 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 
>> Reviewed-by: Christoph Hellwig 
>> ---
>>   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_hintki_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;
> +
> + if (hint <= max_hint)
> + return hint;
> +
> + return 0;
> +}
> +
>   static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
>   {
>   *kiocb = (struct kiocb) {
>   .ki_filp = filp,
>   .ki_flags = iocb_flags(filp),
> - .ki_hint = file_write_hint(filp),
> + .ki_hint = ki_hint_validate(file_write_hint(filp)),
>   };
>   }

Looks good. I'll resubmit.

>   
> 

Re: [PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[Adam Manzanares]

On 5/22/18 8:32 AM, Jens Axboe wrote:
> On 5/22/18 9:07 AM, adam.manzana...@wdc.com wrote:
>> From: Adam Manzanares 
>>
>> 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 
>> Reviewed-by: Christoph Hellwig 
>> ---
>>   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_hintki_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;
> +
> + if (hint <= max_hint)
> + return hint;
> +
> + return 0;
> +}
> +
>   static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
>   {
>   *kiocb = (struct kiocb) {
>   .ki_filp = filp,
>   .ki_flags = iocb_flags(filp),
> - .ki_hint = file_write_hint(filp),
> + .ki_hint = ki_hint_validate(file_write_hint(filp)),
>   };
>   }

Looks good. I'll resubmit.

>   
> 

Re: [PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[Jens Axboe]

On 5/22/18 9:07 AM, adam.manzana...@wdc.com wrote:
> From: Adam Manzanares 
> 
> 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 
> Reviewed-by: Christoph Hellwig 
> ---
>  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_hintki_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;
+
+   if (hint <= max_hint)
+   return hint;
+
+   return 0;
+}
+
 static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
 {
*kiocb = (struct kiocb) {
.ki_filp = filp,
.ki_flags = iocb_flags(filp),
-   .ki_hint = file_write_hint(filp),
+   .ki_hint = ki_hint_validate(file_write_hint(filp)),
};
 }
 

-- 
Jens Axboe

Re: [PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[Jens Axboe]

On 5/22/18 9:07 AM, adam.manzana...@wdc.com wrote:
> From: Adam Manzanares 
> 
> 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 
> Reviewed-by: Christoph Hellwig 
> ---
>  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_hintki_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;
+
+   if (hint <= max_hint)
+   return hint;
+
+   return 0;
+}
+
 static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
 {
*kiocb = (struct kiocb) {
.ki_filp = filp,
.ki_flags = iocb_flags(filp),
-   .ki_hint = file_write_hint(filp),
+   .ki_hint = ki_hint_validate(file_write_hint(filp)),
};
 }
 

-- 
Jens Axboe

[PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[adam . manzanares]

From: Adam Manzanares 

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 
Reviewed-by: Christoph Hellwig 
---
 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 */
+
 #define IOCB_EVENTFD   (1 << 0)
 #define IOCB_APPEND(1 << 1)
 #define IOCB_DIRECT(1 << 2)
@@ -299,7 +301,7 @@ struct kiocb {
void (*ki_complete)(struct kiocb *iocb, long ret, long ret2);
void*private;
int ki_flags;
-   enum rw_hintki_hint;
+   u16 ki_hint;
 } __randomize_layout;
 
 static inline bool is_sync_kiocb(struct kiocb *kiocb)
@@ -1927,12 +1929,19 @@ 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)
+{
+   if (hint > MAX_KI_HINT)
+   return 0;
+   return hint;
+}
+
 static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
 {
*kiocb = (struct kiocb) {
.ki_filp = filp,
.ki_flags = iocb_flags(filp),
-   .ki_hint = file_write_hint(filp),
+   .ki_hint = ki_hint_validate(file_write_hint(filp)),
};
 }
 
-- 
2.15.1

[PATCH v6 2/5] fs: Convert kiocb rw_hint from enum to u16

[adam . manzanares]

From: Adam Manzanares 

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 
Reviewed-by: Christoph Hellwig 
---
 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 */
+
 #define IOCB_EVENTFD   (1 << 0)
 #define IOCB_APPEND(1 << 1)
 #define IOCB_DIRECT(1 << 2)
@@ -299,7 +301,7 @@ struct kiocb {
void (*ki_complete)(struct kiocb *iocb, long ret, long ret2);
void*private;
int ki_flags;
-   enum rw_hintki_hint;
+   u16 ki_hint;
 } __randomize_layout;
 
 static inline bool is_sync_kiocb(struct kiocb *kiocb)
@@ -1927,12 +1929,19 @@ 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)
+{
+   if (hint > MAX_KI_HINT)
+   return 0;
+   return hint;
+}
+
 static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
 {
*kiocb = (struct kiocb) {
.ki_filp = filp,
.ki_flags = iocb_flags(filp),
-   .ki_hint = file_write_hint(filp),
+   .ki_hint = ki_hint_validate(file_write_hint(filp)),
};
 }
 
-- 
2.15.1