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block: return errors from blk_execute_rq()

PATCH In review Keith Busch 2 participants 4 messages Apr 23, 2021 – Apr 26, 2021

Subsystems (2)
Block layer NVMe
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Keith Busch

author maintainer
#0 lore raw

PATCH 1/2 block: return errors from blk_execute_rq()

The synchronous blk_execute_rq() had not provided a way for its callers to know if its request was successful or not. Return the errno from the completion status.

Reported-by Yuanyuan Zhong <[email protected]>
Signed-off-by Keith Busch <[email protected]>
---
 block/blk-exec.c       | 6 ++++--
 include/linux/blkdev.h | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)
block/blk-exec.c +4 -2
index beae70a0e5e5..3877a2677dd4 100644
@@ -21,7 +21,7 @@ static void blk_end_sync_rq(struct request *rq, blk_status_t error)
 {
 	struct completion *waiting = rq->end_io_data;
 
-	rq->end_io_data = NULL;
+	rq->end_io_data = ERR_PTR(blk_status_to_errno(error));
 
 	/*
 	 * complete last, if this is a stack request the process (and thus

@@ -72,8 +72,9 @@ EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
  * Description:
  *    Insert a fully prepared request at the back of the I/O scheduler queue
  *    for execution and wait for completion.
+ * Return: The errno value of the blk_status_t provided to blk_mq_end_request().
  */
-void blk_execute_rq(struct gendisk *bd_disk, struct request *rq, int at_head)
+int blk_execute_rq(struct gendisk *bd_disk, struct request *rq, int at_head)
 {
 	DECLARE_COMPLETION_ONSTACK(wait);
 	unsigned long hang_check;

@@ -87,5 +88,6 @@ void blk_execute_rq(struct gendisk *bd_disk, struct request *rq, int at_head)
 		while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
 	else
 		wait_for_completion_io(&wait);
+	return PTR_ERR_OR_ZERO(rq->end_io_data);
 }
 EXPORT_SYMBOL(blk_execute_rq);
include/linux/blkdev.h +1 -1
index b91ba6207365..15e4ffac33af 100644
@@ -938,7 +938,7 @@ extern int blk_rq_map_kern(struct request_queue *, struct request *, void *, uns
 extern int blk_rq_map_user_iov(struct request_queue *, struct request *,
 			       struct rq_map_data *, const struct iov_iter *,
 			       gfp_t);
-extern void blk_execute_rq(struct gendisk *, struct request *, int);
+extern int blk_execute_rq(struct gendisk *, struct request *, int);
 extern void blk_execute_rq_nowait(struct gendisk *,
 				  struct request *, int, rq_end_io_fn *);
Signature · 1 line
2.25.4
author maintainer
#1 lore raw

PATCH 2/2 nvme: use return value from blk_execute_rq()

We don't have an nvme status to report if the driver's .queue_rq() returns an error without dispatching the requested nvme command. Use the return value from blk_execute_rq() so the caller may know their command was not successful.

Reported-by Yuanyuan Zhong <[email protected]>
Signed-off-by Keith Busch <[email protected]>
---
 drivers/nvme/host/core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
drivers/nvme/host/core.c +2 -2
index 85538c38aae9..b57157106cac 100644
@@ -1000,12 +1000,12 @@ int __nvme_submit_sync_cmd(struct request_queue *q, struct nvme_command *cmd,
 	if (poll)
 		nvme_execute_rq_polled(req->q, NULL, req, at_head);
 	else
-		blk_execute_rq(NULL, req, at_head);
+		ret = blk_execute_rq(NULL, req, at_head);
 	if (result)
 		*result = nvme_req(req)->result;
 	if (nvme_req(req)->flags & NVME_REQ_CANCELLED)
 		ret = -EINTR;
-	else
+	else if (nvme_req(req)->status)
 		ret = nvme_req(req)->status;
  out:
 	blk_mq_free_request(req);
Signature · 1 line
2.25.4
author maintainer
#2 lore raw
In reply to Keith Busch

Sorry, please disregard this series. This came from the directory of the first version of this patch, but I intended to send the v2.

maintainer
#3 lore raw
In reply to Keith Busch
Quoted 16 lines · Keith Busch

The synchronous blk_execute_rq() had not provided a way for its callers to know if its request was successful or not. Return the errno from the completion status.

Reported-by Yuanyuan Zhong <[email protected]>
Signed-off-by Keith Busch <[email protected]>
---
 block/blk-exec.c       | 6 ++++--
 include/linux/blkdev.h | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)
block/blk-exec.c +0 -0
index beae70a0e5e5..3877a2677dd4 100644

block/blk-exec.c static void blk_end_sync_rq(struct request *rq, blk_status_t error) · line 24

Quoted 5 lines
block/blk-exec.c +1 -1
@@ -21,7 +21,7 @@ static void blk_end_sync_rq(struct request *rq, blk_status_t error)
 {
 	struct completion *waiting = rq->end_io_data;
 
-	rq->end_io_data = NULL;
+	rq->end_io_data = ERR_PTR(blk_status_to_errno(error));

I think we should propagate the blk_status_t here as we're entirely inside the block layer. I.e. declare a blk_status_t on-stack in blk_execute_rq and pass a pointer to it in ->end_io_data.

block/blk-exec.c static void blk_end_sync_rq(struct request *rq, blk_status_t error) · line 25

Quoted 2 lines
block/blk-exec.c +1 -1
-extern void blk_execute_rq(struct gendisk *, struct request *, int);
+extern int blk_execute_rq(struct gendisk *, struct request *, int);

It would be nice to drop the extern here and spell out the argument names.