blk-mq-tag: change busy_iter_fn to return whether to continue or not

We have this functionality in sbitmap, but we don't export it in
blk-mq for users of the tags busy iteration. This can be useful
for stopping the iteration, if the caller doesn't need to find
more requests.

Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq-debugfs.c

@@ -422,15 +422,18 @@ struct show_busy_params {
 
 /*
  * Note: the state of a request may change while this function is in progress,
- * e.g. due to a concurrent blk_mq_finish_request() call.
+ * e.g. due to a concurrent blk_mq_finish_request() call. Returns true to
+ * keep iterating requests.
  */
-static void hctx_show_busy_rq(struct request *rq, void *data, bool reserved)
+static bool hctx_show_busy_rq(struct request *rq, void *data, bool reserved)
 {
 	const struct show_busy_params *params = data;
 
 	if (rq->mq_hctx == params->hctx)
 		__blk_mq_debugfs_rq_show(params->m,
 					 list_entry_rq(&rq->queuelist));
+
+	return true;
 }
 
 static int hctx_busy_show(void *data, struct seq_file *m)

block/blk-mq-tag.c

@@ -236,7 +236,7 @@ static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
 	 * test and set the bit before assigning ->rqs[].
 	 */
 	if (rq && rq->q == hctx->queue)
-		iter_data->fn(hctx, rq, iter_data->data, reserved);
+		return iter_data->fn(hctx, rq, iter_data->data, reserved);
 	return true;
 }
 
@@ -289,7 +289,7 @@ static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data)
 	 */
 	rq = tags->rqs[bitnr];
 	if (rq && blk_mq_request_started(rq))
-		iter_data->fn(rq, iter_data->data, reserved);
+		return iter_data->fn(rq, iter_data->data, reserved);
 
 	return true;
 }

block/blk-mq.c

@@ -94,7 +94,7 @@ struct mq_inflight {
 	unsigned int *inflight;
 };
 
-static void blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
+static bool blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
 				  struct request *rq, void *priv,
 				  bool reserved)
 {
@@ -109,6 +109,8 @@ static void blk_mq_check_inflight(struct blk_mq_hw_ctx *hctx,
 		mi->inflight[0]++;
 	if (mi->part->partno)
 		mi->inflight[1]++;
+
+	return true;
 }
 
 void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part,
@@ -120,7 +122,7 @@ void blk_mq_in_flight(struct request_queue *q, struct hd_struct *part,
 	blk_mq_queue_tag_busy_iter(q, blk_mq_check_inflight, &mi);
 }
 
-static void blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
+static bool blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
 				     struct request *rq, void *priv,
 				     bool reserved)
 {
@@ -128,6 +130,8 @@ static void blk_mq_check_inflight_rw(struct blk_mq_hw_ctx *hctx,
 
 	if (rq->part == mi->part)
 		mi->inflight[rq_data_dir(rq)]++;
+
+	return true;
 }
 
 void blk_mq_in_flight_rw(struct request_queue *q, struct hd_struct *part,
@@ -821,7 +825,7 @@ static bool blk_mq_req_expired(struct request *rq, unsigned long *next)
 	return false;
 }
 
-static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
+static bool blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
 		struct request *rq, void *priv, bool reserved)
 {
 	unsigned long *next = priv;
@@ -831,7 +835,7 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
 	 * so we're not unnecessarilly synchronizing across CPUs.
 	 */
 	if (!blk_mq_req_expired(rq, next))
-		return;
+		return true;
 
 	/*
 	 * We have reason to believe the request may be expired. Take a
@@ -843,7 +847,7 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
 	 * timeout handler to posting a natural completion.
 	 */
 	if (!refcount_inc_not_zero(&rq->ref))
-		return;
+		return true;
 
 	/*
 	 * The request is now locked and cannot be reallocated underneath the
@@ -855,6 +859,8 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
 		blk_mq_rq_timed_out(rq, reserved);
 	if (refcount_dec_and_test(&rq->ref))
 		__blk_mq_free_request(rq);
+
+	return true;
 }
 
 static void blk_mq_timeout_work(struct work_struct *work)

drivers/block/mtip32xx/mtip32xx.c

@@ -2720,7 +2720,7 @@ static void mtip_softirq_done_fn(struct request *rq)
 	blk_mq_end_request(rq, cmd->status);
 }
 
-static void mtip_abort_cmd(struct request *req, void *data, bool reserved)
+static bool mtip_abort_cmd(struct request *req, void *data, bool reserved)
 {
 	struct mtip_cmd *cmd = blk_mq_rq_to_pdu(req);
 	struct driver_data *dd = data;
@@ -2730,14 +2730,16 @@ static void mtip_abort_cmd(struct request *req, void *data, bool reserved)
 	clear_bit(req->tag, dd->port->cmds_to_issue);
 	cmd->status = BLK_STS_IOERR;
 	mtip_softirq_done_fn(req);
+	return true;
 }
 
-static void mtip_queue_cmd(struct request *req, void *data, bool reserved)
+static bool mtip_queue_cmd(struct request *req, void *data, bool reserved)
 {
 	struct driver_data *dd = data;
 
 	set_bit(req->tag, dd->port->cmds_to_issue);
 	blk_abort_request(req);
+	return true;
 }
 
 /*
@@ -3920,12 +3922,13 @@ protocol_init_error:
 	return rv;
 }
 
-static void mtip_no_dev_cleanup(struct request *rq, void *data, bool reserv)
+static bool mtip_no_dev_cleanup(struct request *rq, void *data, bool reserv)
 {
 	struct mtip_cmd *cmd = blk_mq_rq_to_pdu(rq);
 
 	cmd->status = BLK_STS_IOERR;
 	blk_mq_complete_request(rq);
+	return true;
 }
 
 /*

drivers/block/nbd.c

@@ -734,12 +734,13 @@ static void recv_work(struct work_struct *work)
 	kfree(args);
 }
 
-static void nbd_clear_req(struct request *req, void *data, bool reserved)
+static bool nbd_clear_req(struct request *req, void *data, bool reserved)
 {
 	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
 
 	cmd->status = BLK_STS_IOERR;
 	blk_mq_complete_request(req);
+	return true;
 }
 
 static void nbd_clear_que(struct nbd_device *nbd)

drivers/block/skd_main.c

@@ -382,11 +382,12 @@ static void skd_log_skreq(struct skd_device *skdev,
  * READ/WRITE REQUESTS
  *****************************************************************************
  */
-static void skd_inc_in_flight(struct request *rq, void *data, bool reserved)
+static bool skd_inc_in_flight(struct request *rq, void *data, bool reserved)
 {
 	int *count = data;
 
 	count++;
+	return true;
 }
 
 static int skd_in_flight(struct skd_device *skdev)
@@ -1887,13 +1888,13 @@ static void skd_isr_fwstate(struct skd_device *skdev)
 		skd_skdev_state_to_str(skdev->state), skdev->state);
 }
 
-static void skd_recover_request(struct request *req, void *data, bool reserved)
+static bool skd_recover_request(struct request *req, void *data, bool reserved)
 {
 	struct skd_device *const skdev = data;
 	struct skd_request_context *skreq = blk_mq_rq_to_pdu(req);
 
 	if (skreq->state != SKD_REQ_STATE_BUSY)
-		return;
+		return true;
 
 	skd_log_skreq(skdev, skreq, "recover");
 
@@ -1904,6 +1905,7 @@ static void skd_recover_request(struct request *req, void *data, bool reserved)
 	skreq->state = SKD_REQ_STATE_IDLE;
 	skreq->status = BLK_STS_IOERR;
 	blk_mq_complete_request(req);
+	return true;
 }
 
 static void skd_recover_requests(struct skd_device *skdev)

drivers/nvme/host/core.c

@@ -268,14 +268,14 @@ void nvme_complete_rq(struct request *req)
 }
 EXPORT_SYMBOL_GPL(nvme_complete_rq);
 
-void nvme_cancel_request(struct request *req, void *data, bool reserved)
+bool nvme_cancel_request(struct request *req, void *data, bool reserved)
 {
 	dev_dbg_ratelimited(((struct nvme_ctrl *) data)->device,
 				"Cancelling I/O %d", req->tag);
 
 	nvme_req(req)->status = NVME_SC_ABORT_REQ;
 	blk_mq_complete_request(req);
-
+	return true;
 }
 EXPORT_SYMBOL_GPL(nvme_cancel_request);
 

drivers/nvme/host/fc.c

@@ -2386,7 +2386,7 @@ nvme_fc_complete_rq(struct request *rq)
  * status. The done path will return the io request back to the block
  * layer with an error status.
  */
-static void
+static bool
 nvme_fc_terminate_exchange(struct request *req, void *data, bool reserved)
 {
 	struct nvme_ctrl *nctrl = data;
@@ -2394,6 +2394,7 @@ nvme_fc_terminate_exchange(struct request *req, void *data, bool reserved)
 	struct nvme_fc_fcp_op *op = blk_mq_rq_to_pdu(req);
 
 	__nvme_fc_abort_op(ctrl, op);
+	return true;
 }
 
 

drivers/nvme/host/nvme.h

@@ -408,7 +408,7 @@ static inline void nvme_put_ctrl(struct nvme_ctrl *ctrl)
 }
 
 void nvme_complete_rq(struct request *req);
-void nvme_cancel_request(struct request *req, void *data, bool reserved);
+bool nvme_cancel_request(struct request *req, void *data, bool reserved);
 bool nvme_change_ctrl_state(struct nvme_ctrl *ctrl,
 		enum nvme_ctrl_state new_state);
 int nvme_disable_ctrl(struct nvme_ctrl *ctrl, u64 cap);

include/linux/blk-mq.h

@@ -129,9 +129,9 @@ typedef int (init_request_fn)(struct blk_mq_tag_set *set, struct request *,
 typedef void (exit_request_fn)(struct blk_mq_tag_set *set, struct request *,
 		unsigned int);
 
-typedef void (busy_iter_fn)(struct blk_mq_hw_ctx *, struct request *, void *,
+typedef bool (busy_iter_fn)(struct blk_mq_hw_ctx *, struct request *, void *,
 		bool);
-typedef void (busy_tag_iter_fn)(struct request *, void *, bool);
+typedef bool (busy_tag_iter_fn)(struct request *, void *, bool);
 typedef int (poll_fn)(struct blk_mq_hw_ctx *, unsigned int);
 typedef int (map_queues_fn)(struct blk_mq_tag_set *set);
 typedef bool (busy_fn)(struct request_queue *);