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Commit 1d0903d6 authored by Zhang Yi's avatar Zhang Yi Committed by Jens Axboe
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blk-wbt: introduce a new disable state to prevent false positive by rwb_enabled()



Now that we disable wbt by simply zero out rwb->wb_normal in
wbt_disable_default() when switch elevator to bfq, but it's not safe
because it will become false positive if we change queue depth. If it
become false positive between wbt_wait() and wbt_track() when submit
write request, it will lead to drop rqw->inflight to -1 in wbt_done(),
which will end up trigger IO hung. Fix this issue by introduce a new
state which mean the wbt was disabled.

Fixes: a7905043 ("blk-rq-qos: refactor out common elements of blk-wbt")
Signed-off-by: default avatarZhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/r/20210619093700.920393-2-yi.zhang@huawei.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent fb926032
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