[PATCH AUTOSEL 5.8 095/132] block: Consider only dispatched requests for inflight statistic

[PATCH AUTOSEL 5.8 095/132] block: Consider only dispatched requests for inflight statistic

[Sasha Levin]

From: Gabriel Krisman Bertazi <krisman@collabora.com>

[ Upstream commit a926c7afffcc0f2e35e6acbccb16921bacf34617 ]

According to Documentation/block/stat.rst, inflight should not include
I/O requests that are in the queue but not yet dispatched to the device,
but blk-mq identifies as inflight any request that has a tag allocated,
which, for queues without elevator, happens at request allocation time
and before it is queued in the ctx (default case in blk_mq_submit_bio).

In addition, current behavior is different for queues with elevator from
queues without it, since for the former the driver tag is allocated at
dispatch time.  A more precise approach would be to only consider
requests with state MQ_RQ_IN_FLIGHT.

This effectively reverts commit 6131837b1de6 ("blk-mq: count allocated
but not started requests in iostats inflight") to consolidate blk-mq
behavior with itself (elevator case) and with original documentation,
but it differs from the behavior used by the legacy path.

This version differs from v1 by using blk_mq_rq_state to access the
state attribute.  Avoid using blk_mq_request_started, which was
suggested, since we don't want to include MQ_RQ_COMPLETE.

Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 block/blk-mq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 8e623e0282757..88b0dc0034cff 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -103,7 +103,7 @@ static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
 {
 	struct mq_inflight *mi = priv;
 
-	if (rq->part == mi->part)
+	if (rq->part == mi->part && blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT)
 		mi->inflight[rq_data_dir(rq)]++;
 
 	return true;
-- 
2.25.1

[PATCH AUTOSEL 5.8 130/132] nbd: make the config put is called before the notifying the waiter

[Sasha Levin]

From: Xiubo Li <xiubli@redhat.com>

[ Upstream commit 87aac3a80af5cbad93e63250e8a1e19095ba0d30 ]

There has one race case for ceph's rbd-nbd tool. When do mapping
it may fail with EBUSY from ioctl(nbd, NBD_DO_IT), but actually
the nbd device has already unmaped.

It dues to if just after the wake_up(), the recv_work() is scheduled
out and defers calling the nbd_config_put(), though the map process
has exited the "nbd->recv_task" is not cleared.

Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/block/nbd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index bc9dc1f847e19..955b754fd5555 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -798,9 +798,9 @@ static void recv_work(struct work_struct *work)
 
 		blk_mq_complete_request(blk_mq_rq_from_pdu(cmd));
 	}
+	nbd_config_put(nbd);
 	atomic_dec(&config->recv_threads);
 	wake_up(&config->recv_wq);
-	nbd_config_put(nbd);
 	kfree(args);
 }
 
-- 
2.25.1