| Message ID | 20180814155749.28912-1-ming.lei@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | blk-wbt: fix IO hang in wbt_wait() | expand |
On 8/14/18 9:57 AM, Ming Lei wrote: > On wbt invariant is that if one IO is tracked via WBT_TRACKED, rqw->inflight > should be updated for tracking this IO. > > But commit c1c80384c8f ("block: remove external dependency on wbt_flags") > forgets to remove the early handling of !rwb_enabled(rwb) inside wbt_wait(), > then the inflight counter may not be increased in wbt_wait(), but decreased > in wbt_done() for this kind of IO, so this counter may become negative, then > wbt_wait() may wait forever. > > This patch fixes the report in the following link: > > https://marc.info/?l=linux-block&m=153221542021033&w=2 Looks good to me, thanks for fixing this. Applied.
diff --git a/block/blk-wbt.c b/block/blk-wbt.c index 1d94a20374fc..bb93c7c2b182 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -576,12 +576,8 @@ static void wbt_wait(struct rq_qos *rqos, struct bio *bio, spinlock_t *lock) struct rq_wb *rwb = RQWB(rqos); enum wbt_flags flags; - if (!rwb_enabled(rwb)) - return; - flags = bio_to_wbt_flags(rwb, bio); - - if (!wbt_should_throttle(rwb, bio)) { + if (!(flags & WBT_TRACKED)) { if (flags & WBT_READ) wb_timestamp(rwb, &rwb->last_issue); return;
On wbt invariant is that if one IO is tracked via WBT_TRACKED, rqw->inflight should be updated for tracking this IO. But commit c1c80384c8f ("block: remove external dependency on wbt_flags") forgets to remove the early handling of !rwb_enabled(rwb) inside wbt_wait(), then the inflight counter may not be increased in wbt_wait(), but decreased in wbt_done() for this kind of IO, so this counter may become negative, then wbt_wait() may wait forever. This patch fixes the report in the following link: https://marc.info/?l=linux-block&m=153221542021033&w=2 Fixes: c1c80384c8f ("block: remove external dependency on wbt_flags") Cc: Josef Bacik <jbacik@fb.com> Reported-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> --- block/blk-wbt.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-)