From e44362ce317bcc46d409ed6c4a5ed2b46804bcbf Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 23 Feb 2021 14:46:50 +0000 Subject: [PATCH] block/export: fix vhost-user-blk export sector number calculation The driver is supposed to honor the blk_size field but the protocol still uses 512-byte sector numbers. It is incorrect to multiply req->sector_num by blk_size. VIRTIO 1.1 5.2.5 Device Initialization says: blk_size can be read to determine the optimal sector size for the driver to use. This does not affect the units used in the protocol (always 512 bytes), but awareness of the correct value can affect performance. Fixes: 3578389bcf76c824a5d82e6586a6f0c71e56f2aa ("block/export: vhost-user block device backend server") Signed-off-by: Stefan Hajnoczi Message-Id: <20210223144653.811468-10-stefanha@redhat.com> Signed-off-by: Kevin Wolf --- block/export/vhost-user-blk-server.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c index 2614a63791..f74796241c 100644 --- a/block/export/vhost-user-blk-server.c +++ b/block/export/vhost-user-blk-server.c @@ -144,7 +144,7 @@ static void coroutine_fn vu_blk_virtio_process_req(void *opaque) break; } - int64_t offset = req->sector_num * vexp->blk_size; + int64_t offset = req->sector_num << VIRTIO_BLK_SECTOR_BITS; QEMUIOVector qiov; if (is_write) { qemu_iovec_init_external(&qiov, out_iov, out_num);