>> [1]
http://download.breakpoint.cc/bug/bug_patch2.jpeg 134 KiB
>
>OK, can you see what this produces?
>
>diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
>index 61fdaf0..4042269 100644
>--- a/drivers/scsi/scsi_lib.c
>+++ b/drivers/scsi/scsi_lib.c
>@@ -1115,6 +1115,8 @@ static int scsi_init_io(struct scsi_cmnd *cmd)
> * kmapping pages)
> */
> cmd->use_sg = req->nr_phys_segments;
>+ if (!cmd->use_sg)
>+ return 0;
>
> /*
> * If sg table allocation fails, requeue request later.
>@@ -1191,7 +1193,7 @@ int scsi_setup_blk_pc_cmnd(struct scsi_device *sdev, struct request *req)
> if (req->bio) {
> int ret;
>
>- BUG_ON(!req->nr_phys_segments);
>+ BUG_ON(!req->nr_phys_segments && req->bio->bi_size);
>
> ret = scsi_init_io(cmd);
> if (unlikely(ret))
>@@ -1236,9 +1238,11 @@ int scsi_setup_fs_cmnd(struct scsi_device *sdev, struct request *req)
> if (ret != BLKPREP_OK)
> return ret;
> /*
>- * Filesystem requests must transfer data.
>+ * Filesystem requests must transfer data, unless it's an empty
>+ * barrier.
> */
>- BUG_ON(!req->nr_phys_segments);
>+ if (!req->nr_phys_segments && !bio_empty_barrier(req->bio))
>+ blk_dump_rq_flags(req, "scsi");
>
> cmd = scsi_get_cmd_from_req(sdev, req);
> if (unlikely(!cmd))
