We can't control a VM's vhost scsi IO right now because the vhost worker
is added to the VM's blk cgroup, but the vhost worker thread actually
just passes the cmd to a vhost-scsi driver workqueue which ends up
submitting the cmd to the block layer.
This patch has us submit from the vhost worker thread and removes the
work queue.
Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
---
drivers/vhost/scsi.c | 30 +++---------------------------
1 file changed, 3 insertions(+), 27 deletions(-)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 4e91a90..3178bf54 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -101,8 +101,6 @@ struct vhost_scsi_cmd {
struct vhost_scsi_nexus *tvc_nexus;
/* The TCM I/O descriptor that is accessed via container_of() */
struct se_cmd tvc_se_cmd;
- /* work item used for cmwq dispatch to vhost_scsi_submission_work() */
- struct work_struct work;
/* Copy of the incoming SCSI command descriptor block (CDB) */
unsigned char tvc_cdb[VHOST_SCSI_MAX_CDB_SIZE];
/* Sense buffer that will be mapped into outgoing status */
@@ -240,8 +238,6 @@ struct vhost_scsi_ctx {
struct iov_iter out_iter;
};
-static struct workqueue_struct *vhost_scsi_workqueue;
-
/* Global spinlock to protect vhost_scsi TPG list for vhost IOCTL access */
static DEFINE_MUTEX(vhost_scsi_mutex);
static LIST_HEAD(vhost_scsi_list);
@@ -776,10 +772,8 @@ static int vhost_scsi_to_tcm_attr(int attr)
return TCM_SIMPLE_TAG;
}
-static void vhost_scsi_submission_work(struct work_struct *work)
+static void vhost_scsi_target_submit(struct vhost_scsi_cmd *cmd)
{
- struct vhost_scsi_cmd *cmd =
- container_of(work, struct vhost_scsi_cmd, work);
struct vhost_scsi_nexus *tv_nexus;
struct se_cmd *se_cmd = &cmd->tvc_se_cmd;
struct scatterlist *sg_ptr, *sg_prot_ptr = NULL;
@@ -1126,14 +1120,7 @@ static u16 vhost_buf_to_lun(u8 *lun_buf)
* vhost_scsi_queue_data_in() and vhost_scsi_queue_status()
*/
cmd->tvc_vq_desc = vc.head;
- /*
- * Dispatch cmd descriptor for cmwq execution in process
- * context provided by vhost_scsi_workqueue. This also ensures
- * cmd is executed on the same kworker CPU as this vhost
- * thread to gain positive L2 cache locality effects.
- */
- INIT_WORK(&cmd->work, vhost_scsi_submission_work);
- queue_work(vhost_scsi_workqueue, &cmd->work);
+ vhost_scsi_target_submit(cmd);
ret = 0;
err:
/*
@@ -2511,17 +2498,9 @@ static int __init vhost_scsi_init(void)
" on "UTS_RELEASE"\n", VHOST_SCSI_VERSION, utsname()->sysname,
utsname()->machine);
- /*
- * Use our own dedicated workqueue for submitting I/O into
- * target core to avoid contention within system_wq.
- */
- vhost_scsi_workqueue = alloc_workqueue("vhost_scsi", 0, 0);
- if (!vhost_scsi_workqueue)
- goto out;
-
ret = vhost_scsi_register();
if (ret < 0)
- goto out_destroy_workqueue;
+ goto out;
ret = target_register_template(&vhost_scsi_ops);
if (ret < 0)
@@ -2531,8 +2510,6 @@ static int __init vhost_scsi_init(void)
out_vhost_scsi_deregister:
vhost_scsi_deregister();
-out_destroy_workqueue:
- destroy_workqueue(vhost_scsi_workqueue);
out:
return ret;
};
@@ -2541,7 +2518,6 @@ static void vhost_scsi_exit(void)
{
target_unregister_template(&vhost_scsi_ops);
vhost_scsi_deregister();
- destroy_workqueue(vhost_scsi_workqueue);
};
MODULE_DESCRIPTION("VHOST_SCSI series fabric driver");
--
1.8.3.1
