fs/block_dev.c: skip rw_page if bdev has integrity

If a block device has bio integrity enabled, rw_page will bypass the
integrity payload, which is undesirable. Skip rw_page if this is the
case.

Currently brd and zram provide rw_page, and the proposed 'nd' drivers
will too.

Cc: Jens Axboe <axboe@fb.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Suggested-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

fs/block_dev.c

@@ -376,7 +376,7 @@ int bdev_read_page(struct block_device *bdev, sector_t sector,
 			struct page *page)
 {
 	const struct block_device_operations *ops = bdev->bd_disk->fops;
-	if (!ops->rw_page)
+	if (!ops->rw_page || bdev_get_integrity(bdev))
 		return -EOPNOTSUPP;
 	return ops->rw_page(bdev, sector + get_start_sect(bdev), page, READ);
 }
@@ -407,7 +407,7 @@ int bdev_write_page(struct block_device *bdev, sector_t sector,
 	int result;
 	int rw = (wbc->sync_mode == WB_SYNC_ALL) ? WRITE_SYNC : WRITE;
 	const struct block_device_operations *ops = bdev->bd_disk->fops;
-	if (!ops->rw_page)
+	if (!ops->rw_page || bdev_get_integrity(bdev))
 		return -EOPNOTSUPP;
 	set_page_writeback(page);
 	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, rw);