brd: add support for rw_page()

Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dheeraj Reddy <dheeraj.reddy@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/block/brd.c

@@ -360,6 +360,15 @@ static void brd_make_request(struct request_queue *q, struct bio *bio)
 	bio_endio(bio, err);
 }
 
+static int brd_rw_page(struct block_device *bdev, sector_t sector,
+		       struct page *page, int rw)
+{
+	struct brd_device *brd = bdev->bd_disk->private_data;
+	int err = brd_do_bvec(brd, page, PAGE_CACHE_SIZE, 0, rw, sector);
+	page_endio(page, rw & WRITE, err);
+	return err;
+}
+
 #ifdef CONFIG_BLK_DEV_XIP
 static int brd_direct_access(struct block_device *bdev, sector_t sector,
 			void **kaddr, unsigned long *pfn)
@@ -419,6 +428,7 @@ static int brd_ioctl(struct block_device *bdev, fmode_t mode,
 
 static const struct block_device_operations brd_fops = {
 	.owner =		THIS_MODULE,
+	.rw_page =		brd_rw_page,
 	.ioctl =		brd_ioctl,
 #ifdef CONFIG_BLK_DEV_XIP
 	.direct_access =	brd_direct_access,