Revert "scsi: core: fix scsi_host_queue_ready"

This reverts commit 265d59a.

There is fundamental issue in commit 3287286 (scsi: core: avoid
host-wide host_busy counter for scsi_mq) because SCSI's host busy counter
may not be same with counter of blk-mq's inflight tags, especially in case
of none io scheduler.

So revert this commit first.

Cc: Omar Sandoval <[email protected]>,
Cc: "Martin K. Petersen" <[email protected]>,
Cc: James Bottomley <[email protected]>,
Cc: Christoph Hellwig <[email protected]>,
Cc: Don Brace <[email protected]>
Cc: Kashyap Desai <[email protected]>
Cc: Mike Snitzer <[email protected]>
Cc: Hannes Reinecke <[email protected]>
Cc: Laurence Oberman <[email protected]>
Cc: Bart Van Assche <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: Jens Axboe <[email protected]>
Reported-by: Jens Axboe <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

Author: Ming Lei

drivers/scsi/scsi_lib.c

@@ -1611,7 +1611,7 @@ static inline int scsi_host_queue_ready(struct request_queue *q,
 	else
 		busy = 0;
 	if (atomic_read(&shost->host_blocked) > 0) {
-		if (busy)
+		if (busy || scsi_host_busy(shost))
 			goto starved;
 
 		/*