[PATCH 06/13] blk-throttle: Dynamically allocate root group

Vivek Goyal
2011-05-19T19:39:04Z

Currently, we allocate root throtl_grp statically. But as we will be
introducing per cpu stat pointers and that will be allocated
dynamically even for root group, we might as well make whole root
throtl_grp allocation dynamic and treat it in same manner as other
groups.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
block/blk-throttle.c | 27 ++++++++++++---------------
1 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index c201967..68f2ac3 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -88,7 +88,7 @@ struct throtl_data
/* service tree for active throtl groups */
struct throtl_rb_root tg_service_tree;

- struct throtl_grp root_tg;
+ struct throtl_grp *root_tg;
struct request_queue *queue;

/* Total Number of queued bios on READ and WRITE lists */
@@ -233,7 +233,7 @@ throtl_grp *throtl_find_tg(struct throtl_data *td, struct blkio_cgroup *blkcg)
* Avoid lookup in this case
*/
if (blkcg == &blkio_root_cgroup)
- tg = &td->root_tg;
+ tg = td->root_tg;
else
tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key));

@@ -313,7 +313,7 @@ static struct throtl_grp * throtl_get_tg(struct throtl_data *td)

/* Group allocation failed. Account the IO to root group */
if (!tg) {
- tg = &td->root_tg;
+ tg = td->root_tg;
return tg;
}

@@ -1153,18 +1153,16 @@ int blk_throtl_init(struct request_queue *q)
td->limits_changed = false;
INIT_DELAYED_WORK(&td->throtl_work, blk_throtl_work);

- /* Init root group */
- tg = &td->root_tg;
- throtl_init_group(tg);
+ /* alloc and Init root group. */
+ td->queue = q;
+ tg = throtl_alloc_tg(td);

- /*
- * Set root group reference to 2. One reference will be dropped when
- * all groups on tg_list are being deleted during queue exit. Other
- * reference will remain there as we don't want to delete this group
- * as it is statically allocated and gets destroyed when throtl_data
- * goes away.
- */
- atomic_inc(&tg->ref);
+ if (!tg) {
+ kfree(td);
+ return -ENOMEM;
+ }
+
+ td->root_tg = tg;

rcu_read_lock();
blkiocg_add_blkio_group(&blkio_root_cgroup, &tg->blkg, (void *)td,
@@ -1173,7 +1171,6 @@ int blk_throtl_init(struct request_queue *q)
throtl_add_group_to_td_list(td, tg);

/* Attach throtl data to request queue */
- td->queue = q;
q->td = td;
return 0;
}
--
1.7.4.4