From: Jan Kara Date: Thu, 30 Oct 2014 19:43:38 +0000 (+0100) Subject: block: Fix computation of merged request priority X-Git-Tag: firefly_0821_release~176^2~2868^2~3 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=ece9c72accdc45c3a9484dacb1125ce572647288;p=firefly-linux-kernel-4.4.55.git block: Fix computation of merged request priority Priority of a merged request is computed by ioprio_best(). If one of the requests has undefined priority (IOPRIO_CLASS_NONE) and another request has priority from IOPRIO_CLASS_BE, the function will return the undefined priority which is wrong. Fix the function to properly return priority of a request with the defined priority. Fixes: d58cdfb89ce0c6bd5f81ae931a984ef298dbda20 CC: stable@vger.kernel.org Signed-off-by: Jan Kara Reviewed-by: Jeff Moyer Signed-off-by: Jens Axboe --- diff --git a/block/ioprio.c b/block/ioprio.c index e50170ca7c33..31666c92b46a 100644 --- a/block/ioprio.c +++ b/block/ioprio.c @@ -157,14 +157,16 @@ out: int ioprio_best(unsigned short aprio, unsigned short bprio) { - unsigned short aclass = IOPRIO_PRIO_CLASS(aprio); - unsigned short bclass = IOPRIO_PRIO_CLASS(bprio); + unsigned short aclass; + unsigned short bclass; - if (aclass == IOPRIO_CLASS_NONE) - aclass = IOPRIO_CLASS_BE; - if (bclass == IOPRIO_CLASS_NONE) - bclass = IOPRIO_CLASS_BE; + if (!ioprio_valid(aprio)) + aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM); + if (!ioprio_valid(bprio)) + bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM); + aclass = IOPRIO_PRIO_CLASS(aprio); + bclass = IOPRIO_PRIO_CLASS(bprio); if (aclass == bclass) return min(aprio, bprio); if (aclass > bclass)