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authorPaolo Valente <paolo.valente@linaro.org>2019-01-29 14:06:27 +0300
committerJens Axboe <axboe@kernel.dk>2019-01-31 22:50:23 +0300
commitf3218ad8c6acc9b874060814d6d3ddf154463ac9 (patch)
tree6f5be115aed4028905240b168f8d4ab9728c519e /block/bfq-iosched.c
parent218cb897be6940b8d18eec9bcb32eaa28f1ae8ee (diff)
downloadlinux-f3218ad8c6acc9b874060814d6d3ddf154463ac9.tar.xz
block, bfq: make sure queue budgets are not below service received
With some unlucky sequences of events, the function bfq_updated_next_req updates the current budget of a bfq_queue to a lower value than the service received by the queue using such a budget. Unfortunately, if this happens, then the return value of the function bfq_bfqq_budget_left becomes inconsistent. This commit solves this problem by lower-bounding the budget computed in bfq_updated_next_req to the service currently charged to the queue. Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/bfq-iosched.c')
-rw-r--r--block/bfq-iosched.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index 9ea2c4f42501..b0e8006475be 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -907,8 +907,10 @@ static void bfq_updated_next_req(struct bfq_data *bfqd,
*/
return;
- new_budget = max_t(unsigned long, bfqq->max_budget,
- bfq_serv_to_charge(next_rq, bfqq));
+ new_budget = max_t(unsigned long,
+ max_t(unsigned long, bfqq->max_budget,
+ bfq_serv_to_charge(next_rq, bfqq)),
+ entity->service);
if (entity->budget != new_budget) {
entity->budget = new_budget;
bfq_log_bfqq(bfqd, bfqq, "updated next rq: new budget %lu",