An iocb aio_reqprio field is 16-bits (u16) but often handled as an int in the block layer. E.g. ioprio_check_cap() takes an int as argument. With such implicit int casting function calls, the upper 16-bits of the int argument may be left uninitialized by the compiler, resulting in invalid values for the IOPRIO_PRIO_CLASS() macro (garbage upper bits) and in an error return for functions such as ioprio_check_cap().
Fix this by masking the result of the shift by IOPRIO_CLASS_SHIFT bits in the IOPRIO_PRIO_CLASS() macro. The new macro IOPRIO_CLASS_MASK defines the 3-bits mask for the priority class. While at it, cleanup the following: * Apply the mask IOPRIO_PRIO_MASK to the data argument of the IOPRIO_PRIO_VALUE() macro to ignore upper bits of the data value. * Remove unnecessary parenthesis around fixed values in the macro definitions in include/uapi/linux/ioprio.h. * Update the outdated mention of CFQ in the comment describing priority classes and instead mention BFQ and mq-deadline. * Change the argument name of the IOPRIO_PRIO_CLASS() and IOPRIO_PRIO_DATA() macros from "mask" to "ioprio" to reflect the fact that an IO priority value should be passed rather than a mask. * Change the ioprio_valid() macro into an inline function, adding a check on the maximum value of the class of a priority value as defined by the IOPRIO_CLASS_MAX enum value. Move this function to the kernel side in include/linux/ioprio.h. * Remove the unnecessary "else" after the return statements in task_nice_ioclass(). Signed-off-by: Damien Le Moal <[email protected]> Reviewed-by: Hannes Reinecke <[email protected]> --- include/linux/ioprio.h | 15 ++++++++++++--- include/uapi/linux/ioprio.h | 19 +++++++++++-------- 2 files changed, 23 insertions(+), 11 deletions(-) diff --git a/include/linux/ioprio.h b/include/linux/ioprio.h index ef9ad4fb245f..9b3a6d8172b4 100644 --- a/include/linux/ioprio.h +++ b/include/linux/ioprio.h @@ -8,6 +8,16 @@ #include <uapi/linux/ioprio.h> +/* + * Check that a priority value has a valid class. + */ +static inline bool ioprio_valid(unsigned short ioprio) +{ + unsigned short class = IOPRIO_PRIO_CLASS(ioprio); + + return class > IOPRIO_CLASS_NONE && class < IOPRIO_CLASS_MAX; +} + /* * if process has set io priority explicitly, use that. if not, convert * the cpu scheduler nice value to an io priority @@ -25,10 +35,9 @@ static inline int task_nice_ioclass(struct task_struct *task) { if (task->policy == SCHED_IDLE) return IOPRIO_CLASS_IDLE; - else if (task_is_realtime(task)) + if (task_is_realtime(task)) return IOPRIO_CLASS_RT; - else - return IOPRIO_CLASS_BE; + return IOPRIO_CLASS_BE; } /* diff --git a/include/uapi/linux/ioprio.h b/include/uapi/linux/ioprio.h index 77b17e08b0da..abc40965aa96 100644 --- a/include/uapi/linux/ioprio.h +++ b/include/uapi/linux/ioprio.h @@ -5,12 +5,15 @@ /* * Gives us 8 prio classes with 13-bits of data for each class */ -#define IOPRIO_CLASS_SHIFT (13) +#define IOPRIO_CLASS_SHIFT 13 +#define IOPRIO_CLASS_MASK 0x07 #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) -#define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT) -#define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK) -#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data) +#define IOPRIO_PRIO_CLASS(ioprio) \ + (((ioprio) >> IOPRIO_CLASS_SHIFT) & IOPRIO_CLASS_MASK) +#define IOPRIO_PRIO_DATA(ioprio) ((ioprio) & IOPRIO_PRIO_MASK) +#define IOPRIO_PRIO_VALUE(class, data) \ + (((class) << IOPRIO_CLASS_SHIFT) | ((data) & IOPRIO_PRIO_MASK)) /* * These are the io priority groups as implemented by CFQ. RT is the realtime @@ -23,14 +26,14 @@ enum { IOPRIO_CLASS_RT, IOPRIO_CLASS_BE, IOPRIO_CLASS_IDLE, -}; -#define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE) + IOPRIO_CLASS_MAX, +}; /* * 8 best effort priority levels are supported */ -#define IOPRIO_BE_NR (8) +#define IOPRIO_BE_NR 8 enum { IOPRIO_WHO_PROCESS = 1, @@ -41,6 +44,6 @@ enum { /* * Fallback BE priority */ -#define IOPRIO_NORM (4) +#define IOPRIO_NORM 4 #endif /* _UAPI_LINUX_IOPRIO_H */ -- 2.31.1 _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
