On Fri, Jan 12 2018 at 1:54pm -0500,
Bart Van Assche <Bart.VanAssche@xxxxxxx> wrote:
> The intention of commit 6077c2d706097c0 was to address the last mentioned
> case. It may be possible to move the delayed queue rerun from the
> dm_queue_rq() into dm_requeue_original_request(). But I think it would be
> wrong to rerun the queue immediately in case a SCSI target system returns
> "BUSY".
This is my 3rd reply to this email.. 3rd time's the charm? ;)
Here is a patch that will kick the hw queues via blk_mq_requeue_work(),
indirectly from dm-rq.c:__dm_mq_kick_requeue_list(), after a delay if
BLK_STS_RESOURCE is returned from the target.
Your thoughts on this patch as an alternative to commit 6077c2d7060 ?
Thanks,
Mike
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index d8c7259..ab2cfdc 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1570,7 +1570,10 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
if (error && blk_path_error(error)) {
struct multipath *m = ti->private;
- r = DM_ENDIO_REQUEUE;
+ if (r == BLK_STS_RESOURCE)
+ r = DM_ENDIO_DELAY_REQUEUE;
+ else
+ r = DM_ENDIO_REQUEUE;
if (pgpath)
fail_path(pgpath);
diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 6b01298..ab0ed2d 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -315,6 +315,10 @@ static void dm_done(struct request *clone, blk_status_t error, bool mapped)
/* The target wants to requeue the I/O */
dm_requeue_original_request(tio, false);
break;
+ case DM_ENDIO_DELAY_REQUEUE:
+ /* The target wants to requeue the I/O after a delay */
+ dm_requeue_original_request(tio, true);
+ break;
default:
DMWARN("unimplemented target endio return value: %d", r);
BUG();
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 9ba8453..da83f64 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -550,6 +550,7 @@ struct dm_table *dm_swap_table(struct mapped_device *md,
#define DM_ENDIO_DONE 0
#define DM_ENDIO_INCOMPLETE 1
#define DM_ENDIO_REQUEUE 2
+#define DM_ENDIO_DELAY_REQUEUE 3
/*
* Definitions of return values from target map function.
@@ -557,7 +558,7 @@ struct dm_table *dm_swap_table(struct mapped_device *md,
#define DM_MAPIO_SUBMITTED 0
#define DM_MAPIO_REMAPPED 1
#define DM_MAPIO_REQUEUE DM_ENDIO_REQUEUE
-#define DM_MAPIO_DELAY_REQUEUE 3
+#define DM_MAPIO_DELAY_REQUEUE DM_ENDIO_DELAY_REQUEUE
#define DM_MAPIO_KILL 4
#define dm_sector_div64(x, y)( \
