blk-mq: move failure injection out of blk_mq_complete_request

Move the call to blk_should_fake_timeout out of blk_mq_complete_request
and into the drivers, skipping call sites that are obvious error
handlers, and remove the now superflous blk_mq_force_complete_rq helper.
This ensures we don't keep injecting errors into completions that just
terminate the Linux request after the hardware has been reset or the
command has been aborted.

Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 475e1a7..4acae24 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -509,7 +509,8 @@ static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
 		return;
 	kfree(cmd->bvec);
 	cmd->bvec = NULL;
-	blk_mq_complete_request(rq);
+	if (likely(!blk_should_fake_timeout(rq->q)))
+		blk_mq_complete_request(rq);
 }
 
 static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2)
@@ -2048,7 +2049,8 @@ static void loop_handle_cmd(struct loop_cmd *cmd)
 			cmd->ret = ret;
 		else
 			cmd->ret = ret ? -EIO : 0;
-		blk_mq_complete_request(rq);
+		if (likely(!blk_should_fake_timeout(rq->q)))
+			blk_mq_complete_request(rq);
 	}
 }