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authorPaolo Valente <paolo.valente@linaro.org>2021-06-19 16:09:46 +0200
committerJens Axboe <axboe@kernel.dk>2021-06-21 15:03:41 -0600
commitbd3664b362381c4c1473753ebedf0ab242a60d1d (patch)
tree8bc1ea337856d0e4c4759acb81d386bbc6632f32 /crypto/zstd.c
parent7812472f973047a886e4ed9a91d98d6627dd746f (diff)
block, bfq: avoid delayed merge of async queues
Since commit 430a67f9d616 ("block, bfq: merge bursts of newly-created queues"), BFQ may schedule a merge between a newly created sync bfq_queue, say Q2, and the last sync bfq_queue created, say Q1. To this goal, BFQ stores the address of Q1 in the field bic->stable_merge_bfqq of the bic associated with Q2. So, when the time for the possible merge arrives, BFQ knows which bfq_queue to merge Q2 with. In particular, BFQ checks for possible merges on request arrivals. Yet the same bic may also be associated with an async bfq_queue, say Q3. So, if a request for Q3 arrives, then the above check may happen to be executed while the bfq_queue at hand is Q3, instead of Q2. In this case, Q1 happens to be merged with an async bfq_queue. This is not only a conceptual mistake, because async queues are to be kept out of queue merging, but also a bug that leads to inconsistent states. This commits simply filters async queues out of delayed merges. Fixes: 430a67f9d616 ("block, bfq: merge bursts of newly-created queues") Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Link: https://lore.kernel.org/r/20210619140948.98712-6-paolo.valente@linaro.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'crypto/zstd.c')
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