block: use __bio_add_page in bio_copy_kern

Since the bio is allocated with the exact number of pages needed via
blk_rq_map_bio_alloc(), and the loop iterates exactly that many times,
bio_add_page() cannot fail due to insufficient space.  Switch to
__bio_add_page() and remove the dead error handling code.

Suggested-by: Christoph Hellwig <[email protected]>
Reviewed-by: Chaitanya Kulkarni <[email protected]>
Signed-off-by: Yang Xiuwei <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

Author: Yang Xiuwei

block/blk-map.c

@@ -398,8 +398,7 @@ static struct bio *bio_copy_kern(struct request *rq, void *data, unsigned int le
 		if (op_is_write(op))
 			memcpy(page_address(page), p, bytes);
 
-		if (bio_add_page(bio, page, bytes, 0) < bytes)
-			break;
+		__bio_add_page(bio, page, bytes, 0);
 
 		len -= bytes;
 		p += bytes;