block: Expose stacked device queues in sysfs
Currently stacking devices do not have a queue directory in sysfs.
However, many of the I/O characteristics like sector size, maximum
request size, etc. are queue properties.
This patch enables the queue directory for MD/DM devices. The elevator
code has been modified to deal with queues that do not have an I/O
scheduler.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 142a4ac..3ccdadb 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -395,9 +395,6 @@
if (WARN_ON(!q))
return -ENXIO;
- if (!q->request_fn)
- return 0;
-
ret = kobject_add(&q->kobj, kobject_get(&disk_to_dev(disk)->kobj),
"%s", "queue");
if (ret < 0)
@@ -405,6 +402,9 @@
kobject_uevent(&q->kobj, KOBJ_ADD);
+ if (!q->request_fn)
+ return 0;
+
ret = elv_register_queue(q);
if (ret) {
kobject_uevent(&q->kobj, KOBJ_REMOVE);