The 'need_copy' is set when rq_data_dir(req) returns WRITE, in order to copy the written data to persistent page. ".need_copy = rq_data_dir(req) && info->feature_persistent," Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx> --- drivers/block/xen-blkfront.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 03b5fb341e58..dbc32d0a4b1a 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -576,7 +576,7 @@ struct setup_rw_req { struct blkif_request *ring_req; grant_ref_t gref_head; unsigned int id; - /* Only used when persistent grant is used and it's a read request */ + /* Only used when persistent grant is used and it's a write request */ bool need_copy; unsigned int bvec_off; char *bvec_data; -- 2.17.1