linux/zvol_os: fix SET_ERROR with negative return codes

SET_ERROR is our facility for tracking errors internally. The negation
is to match the what the kernel expects from us. Thus, the negation
should happen outside of the SET_ERROR.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Closes #16364

module/os/linux/zfs/zvol_os.c

@@ -730,7 +730,7 @@ zvol_open(struct block_device *bdev, fmode_t flag)
 #endif
 	if (zv == NULL) {
 		rw_exit(&zvol_state_lock);
-		return (SET_ERROR(-ENXIO));
+		return (-SET_ERROR(ENXIO));
 	}
 
 	mutex_enter(&zv->zv_state_lock);
@@ -795,10 +795,10 @@ zvol_open(struct block_device *bdev, fmode_t flag)
 
 #ifdef HAVE_BLKDEV_GET_ERESTARTSYS
 				schedule();
-				return (SET_ERROR(-ERESTARTSYS));
+				return (-SET_ERROR(ERESTARTSYS));
 #else
 				if ((gethrtime() - start) > timeout)
-					return (SET_ERROR(-ERESTARTSYS));
+					return (-SET_ERROR(ERESTARTSYS));
 
 				schedule_timeout_interruptible(
 					MSEC_TO_TICK(10));
@@ -821,7 +821,7 @@ zvol_open(struct block_device *bdev, fmode_t flag)
 			if (zv->zv_open_count == 0)
 				zvol_last_close(zv);
 
-			error = SET_ERROR(-EROFS);
+			error = -SET_ERROR(EROFS);
 		} else {
 			zv->zv_open_count++;
 		}