block: Fix bounce limit setting in DM

blk_queue_bounce_limit() is more than a wrapper about the request queue
limits.bounce_pfn variable.  Introduce blk_queue_bounce_pfn() which can
be called by stacking drivers that wish to set the bounce limit
explicitly.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

block/blk-settings.c

@@ -193,6 +193,23 @@ void blk_queue_bounce_limit(struct request_queue *q, u64 dma_mask)
 }
 EXPORT_SYMBOL(blk_queue_bounce_limit);
 
+/**
+ * blk_queue_bounce_pfn - set the bounce buffer limit for queue
+ * @q: the request queue for the device
+ * @pfn: max address
+ *
+ * Description:
+ *    This function is similar to blk_queue_bounce_limit except it
+ *    neither changes allocation flags, nor does it set up the ISA DMA
+ *    pool. This function should only be used by stacking drivers.
+ *    Hardware drivers should use blk_queue_bounce_limit instead.
+ */
+void blk_queue_bounce_pfn(struct request_queue *q, u64 pfn)
+{
+	q->limits.bounce_pfn = pfn;
+}
+EXPORT_SYMBOL(blk_queue_bounce_pfn);
+
 /**
  * blk_queue_max_sectors - set max sectors for a request for this queue
  * @q:  the request queue for the device

drivers/md/dm-table.c

@@ -920,7 +920,7 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q)
 	blk_queue_max_segment_size(q, t->limits.max_segment_size);
 	blk_queue_max_hw_sectors(q, t->limits.max_hw_sectors);
 	blk_queue_segment_boundary(q, t->limits.seg_boundary_mask);
-	blk_queue_bounce_limit(q, t->limits.bounce_pfn);
+	blk_queue_bounce_pfn(q, t->limits.bounce_pfn);
 
 	if (t->limits.no_cluster)
 		queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER, q);

include/linux/blkdev.h

@@ -910,6 +910,7 @@ extern struct request_queue *blk_init_queue(request_fn_proc *, spinlock_t *);
 extern void blk_cleanup_queue(struct request_queue *);
 extern void blk_queue_make_request(struct request_queue *, make_request_fn *);
 extern void blk_queue_bounce_limit(struct request_queue *, u64);
+extern void blk_queue_bounce_pfn(struct request_queue *, u64);
 extern void blk_queue_max_sectors(struct request_queue *, unsigned int);
 extern void blk_queue_max_hw_sectors(struct request_queue *, unsigned int);
 extern void blk_queue_max_phys_segments(struct request_queue *, unsigned short);