Revert "block, bfq: honor already-setup queue merges"

[ Upstream commit ebc69e897e ]

This reverts commit 2d52c58b9c.

We have had several folks complain that this causes hangs for them, which
is especially problematic as the commit has also hit stable already.

As no resolution seems to be forthcoming right now, revert the patch.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=214503
Fixes: 2d52c58b9c ("block, bfq: honor already-setup queue merges")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Jens Axboe 2021-09-28 06:33:15 -06:00 committed by Greg Kroah-Hartman
parent 89caeb43de
commit 9676ed4dd1

View File

@ -2137,15 +2137,6 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq)
* are likely to increase the throughput.
*/
bfqq->new_bfqq = new_bfqq;
/*
* The above assignment schedules the following redirections:
* each time some I/O for bfqq arrives, the process that
* generated that I/O is disassociated from bfqq and
* associated with new_bfqq. Here we increases new_bfqq->ref
* in advance, adding the number of processes that are
* expected to be associated with new_bfqq as they happen to
* issue I/O.
*/
new_bfqq->ref += process_refs;
return new_bfqq;
}
@ -2205,10 +2196,6 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
{
struct bfq_queue *in_service_bfqq, *new_bfqq;
/* if a merge has already been setup, then proceed with that first */
if (bfqq->new_bfqq)
return bfqq->new_bfqq;
/*
* Prevent bfqq from being merged if it has been created too
* long ago. The idea is that true cooperating processes, and
@ -2223,6 +2210,9 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq,
if (bfq_too_late_for_merging(bfqq))
return NULL;
if (bfqq->new_bfqq)
return bfqq->new_bfqq;
if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq))
return NULL;