From: Zhang Yi yi.zhang@huawei.com
[ Upstream commit 1d0903d61e9645c6330b94247b96dd873dfc11c8 ]
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: a79050434b45 ("blk-rq-qos: refactor out common elements of blk-wbt") Signed-off-by: Zhang Yi yi.zhang@huawei.com Link: https://lore.kernel.org/r/20210619093700.920393-2-yi.zhang@huawei.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- block/blk-wbt.c | 5 +++-- block/blk-wbt.h | 1 + 2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/block/blk-wbt.c b/block/blk-wbt.c index 42aed0160f86..b098ac6a84f0 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -77,7 +77,8 @@ enum {
static inline bool rwb_enabled(struct rq_wb *rwb) { - return rwb && rwb->wb_normal != 0; + return rwb && rwb->enable_state != WBT_STATE_OFF_DEFAULT && + rwb->wb_normal != 0; }
static void wb_timestamp(struct rq_wb *rwb, unsigned long *var) @@ -702,7 +703,7 @@ void wbt_disable_default(struct request_queue *q) rwb = RQWB(rqos); if (rwb->enable_state == WBT_STATE_ON_DEFAULT) { blk_stat_deactivate(rwb->cb); - rwb->wb_normal = 0; + rwb->enable_state = WBT_STATE_OFF_DEFAULT; } } EXPORT_SYMBOL_GPL(wbt_disable_default); diff --git a/block/blk-wbt.h b/block/blk-wbt.h index 16bdc85b8df9..2eb01becde8c 100644 --- a/block/blk-wbt.h +++ b/block/blk-wbt.h @@ -34,6 +34,7 @@ enum { enum { WBT_STATE_ON_DEFAULT = 1, WBT_STATE_ON_MANUAL = 2, + WBT_STATE_OFF_DEFAULT };
struct rq_wb {