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 blk_status_t
result of the request.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Link: https://lore.kernel.org/r/20210610214437.641245-4-kbusch@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: keithbusch

block/blk-exec.c

@@ -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 = (void *)(uintptr_t)error;
 
 	/*
 	 * complete last, if this is a stack request the process (and thus
@@ -85,8 +85,9 @@ static void blk_rq_poll_completion(struct request *rq, struct completion *wait)
  * Description:
  *    Insert a fully prepared request at the back of the I/O scheduler queue
  *    for execution and wait for completion.
+ * Return: The blk_status_t result provided to blk_mq_end_request().
  */
-void blk_execute_rq(struct gendisk *bd_disk, struct request *rq, int at_head)
+blk_status_t blk_execute_rq(struct gendisk *bd_disk, struct request *rq, int at_head)
 {
 	DECLARE_COMPLETION_ONSTACK(wait);
 	unsigned long hang_check;
@@ -103,5 +104,7 @@ 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 (blk_status_t)(uintptr_t)rq->end_io_data;
 }
 EXPORT_SYMBOL(blk_execute_rq);

include/linux/blkdev.h

@@ -909,10 +909,12 @@ 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 void blk_execute_rq_nowait(struct gendisk *,
 				  struct request *, int, rq_end_io_fn *);
 
+blk_status_t blk_execute_rq(struct gendisk *bd_disk, struct request *rq,
+			    int at_head);
+
 /* Helper to convert REQ_OP_XXX to its string format XXX */
 extern const char *blk_op_str(unsigned int op);