scsi: block: Add a queue_max_bytes() helper

Return the max_sectors value in bytes.  Lifted from scsi_ioctl.c.

Link: https://lore.kernel.org/r/20210724072033.1284840-13-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

block/scsi_ioctl.c

@@ -68,18 +68,9 @@ static int sg_set_timeout(struct request_queue *q, int __user *p)
 	return err;
 }
 
-static int max_sectors_bytes(struct request_queue *q)
-{
-	unsigned int max_sectors = queue_max_sectors(q);
-
-	max_sectors = min_t(unsigned int, max_sectors, INT_MAX >> 9);
-
-	return max_sectors << 9;
-}
-
 static int sg_get_reserved_size(struct request_queue *q, int __user *p)
 {
-	int val = min_t(int, q->sg_reserved_size, max_sectors_bytes(q));
+	int val = min(q->sg_reserved_size, queue_max_bytes(q));
 
 	return put_user(val, p);
 }
@@ -94,7 +85,7 @@ static int sg_set_reserved_size(struct request_queue *q, int __user *p)
 	if (size < 0)
 		return -EINVAL;
 
-	q->sg_reserved_size = min(size, max_sectors_bytes(q));
+	q->sg_reserved_size = min_t(unsigned int, size, queue_max_bytes(q));
 	return 0;
 }
 

include/linux/blkdev.h

@@ -1373,6 +1373,11 @@ static inline unsigned int queue_max_sectors(const struct request_queue *q)
 	return q->limits.max_sectors;
 }
 
+static inline unsigned int queue_max_bytes(struct request_queue *q)
+{
+	return min_t(unsigned int, queue_max_sectors(q), INT_MAX >> 9) << 9;
+}
+
 static inline unsigned int queue_max_hw_sectors(const struct request_queue *q)
 {
 	return q->limits.max_hw_sectors;