| Message ID | 20220615161616.5055-1-jack@suse.cz (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: Fix IO priority mess | expand |
diff --git a/block/ioprio.c b/block/ioprio.c index 2fe068fcaad5..62890391fc80 100644 --- a/block/ioprio.c +++ b/block/ioprio.c @@ -157,10 +157,9 @@ static int get_task_ioprio(struct task_struct *p) int ioprio_best(unsigned short aprio, unsigned short bprio) { if (!ioprio_valid(aprio)) - aprio = IOPRIO_DEFAULT; + return bprio; if (!ioprio_valid(bprio)) - bprio = IOPRIO_DEFAULT; - + return aprio; return min(aprio, bprio); }
ioprio_get(2) can be asked to return the best IO priority from several tasks (IOPRIO_WHO_PGRP, IOPRIO_WHO_USER). Currently the call treats tasks without set IO priority as having priority IOPRIO_CLASS_BE/IOPRIO_BE_NORM however this does not really reflect the IO priority the task will get (which depends on task's nice value) and with the following fix it will not even match returned IO priority for a single task. Fix IO priority comparison to treat unset IO priority as the lowest possible one. This way we will return IOPRIO_CLASS_NONE priority only if none of the considered tasks has explicitely set IO priority, otherwise we return the highest set IO priority. This changes userspace visible behavior but this way the caller really gets back the highest set IO priority without contaminating the result with IOPRIO_CLASS_BE/IOPRIO_BE_NORM from tasks which have IO priority unset. Signed-off-by: Jan Kara <jack@suse.cz> --- block/ioprio.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)