Hi Damien Le Moal Damien Le Moal <dlemoal@xxxxxxxxxx> 于2024年7月31日周三 17:28写道： > > On 7/31/24 16:01, Zhiguo Niu wrote: > > Generally, the input of IOPRIO_PRIO_DATA has 16 bits, but the output of > > IOPRIO_PRIO_DATA will be expanded to "UL" from IOPRIO_PRIO_MASK. > > #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) > > This is not reasonable and meaningless, unsigned int is more suitable for it. > > > > So if use format "%d" to print IOPRIO_PRIO_DATA directly, theire will be a > > build warning or error showned as the following, which is from the > > local test when I modify f2fs codes. > > > > fs/f2fs/sysfs.c:348:31: warning: format ‘%d’ expects argument of type ‘int’, > > but argument 4 has type ‘long unsigned int’ [-Wformat=] > > return sysfs_emit(buf, "%s,%d\n", > > ~^ > > %ld > > > > When modules use IOPRIO_PRIO_CLASS & IOPRIO_PRIO_LEVEL get ioprio's class and > > level, their outputs are both unsigned int. > > IOPRIO_CLASS_MASK is: > > #define IOPRIO_CLASS_SHIFT 13 > > #define IOPRIO_NR_CLASSES 8 > > #define IOPRIO_CLASS_MASK (IOPRIO_NR_CLASSES - 1) > > IOPRIO_LEVEL_MASK is: > > #define IOPRIO_LEVEL_NR_BITS 3 > > #define IOPRIO_NR_LEVELS (1 << IOPRIO_LEVEL_NR_BITS) > > #define IOPRIO_LEVEL_MASK (IOPRIO_NR_LEVELS - 1) > > > > Ioprio is passed along as an int internally, so we should not be using an > > unsigned long for IOPRIO_PRIO_MASK to not end up with IOPRIO_PRIO_DATA > > returning an unsigned long as well. > > I would write this commit message like this: > > > An ioprio is passed internally as an int value. When IOPRIO_PRIO_CLASS() and > IOPRIO_PRIO_LEVEL() are used to extract from it the priority class and level, > the values obtained are thus also int. > However, the IOPRIO_PRIO_MASK() macro used to define the IOPRIO_PRIO_DATA() > macro is defined as: > > #define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1) > > that is, the macro gives an unsigned long value, which leads to > IOPRIO_PRIO_DATA() also returning an unsigned long. > > Make things consistent between class, level and data and use int everywhere by > removing forced unsigned long from IOPRIO_PRIO_MASK. Thank you for your professional advice and sharing. I will update this. > > > > -- > Damien Le Moal > Western Digital Research >
