| Message ID | 11fb2ee5-8352-2d35-3154-68637d99b096@kernel.dk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 5/22/18 8:32 AM, Jens Axboe wrote: > On 5/22/18 9:07 AM, adam.manzanares@wdc.com wrote: >> From: Adam Manzanares <adam.manzanares@wdc.com> >> >> 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@wdc.com> >> Reviewed-by: Christoph Hellwig <hch@lst.de> >> --- >> 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; > + > + 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. > >
On 05/22/2018 10:32 AM, Jens Axboe wrote: > On 5/22/18 9:07 AM, adam.manzanares@wdc.com wrote: >> From: Adam Manzanares <adam.manzanares@wdc.com> >> >> 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@wdc.com> >> Reviewed-by: Christoph Hellwig <hch@lst.de> >> --- >> 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.
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.manzanares@wdc.com wrote: >>> From: Adam Manzanares <adam.manzanares@wdc.com> >>> >>> 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@wdc.com> >>> Reviewed-by: Christoph Hellwig <hch@lst.de> >>> --- >>> 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. 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.
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.manzanares@wdc.com wrote: >>>> From: Adam Manzanares <adam.manzanares@wdc.com> >>>> >>>> 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@wdc.com> >>>> Reviewed-by: Christoph Hellwig <hch@lst.de> >>>> --- >>>> 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. > > 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.
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; + + 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)), }; }