| From | lizf@kernel ... | Subject | [PATCH 3.4 149/177] block: Fix computation of merged request priority | Date | Wed, 28 Jan 2015 12:10:07 +0800 |
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From: Jan Kara <jack@suse.cz>
3.4.106-rc1 review patch. If anyone has any objections, please let me know.
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commit ece9c72accdc45c3a9484dacb1125ce572647288 upstream.
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 Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com> [lizf: Backported to 3.4: adjust filename] Signed-off-by: Zefan Li <lizefan@huawei.com> --- fs/ioprio.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/fs/ioprio.c b/fs/ioprio.c index 0f1b951..0dd6a2a 100644 --- a/fs/ioprio.c +++ b/fs/ioprio.c @@ -153,14 +153,16 @@ 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) -- 1.9.1
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