[PATCH 07/13] blk-throttle: Introduce a helper function to fill in device details

Vivek Goyal
2011-05-19T19:40:46Z

A helper function for the code which is used at 2-3 places. Makes reading
code little easier.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
block/blk-throttle.c | 35 +++++++++++++++++++++++------------
1 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 68f2ac3..97ea7f8 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -188,16 +188,34 @@ throtl_add_group_to_td_list(struct throtl_data *td, struct throtl_grp *tg)
td->nr_undestroyed_grps++;
}

-static void throtl_init_add_tg_lists(struct throtl_data *td,
- struct throtl_grp *tg, struct blkio_cgroup *blkcg)
+static void
+__throtl_tg_fill_dev_details(struct throtl_data *td, struct throtl_grp *tg)
{
struct backing_dev_info *bdi = &td->queue->backing_dev_info;
unsigned int major, minor;

+ if (!tg || tg->blkg.dev)
+ return;
+
+ /*
+ * Fill in device details for a group which might not have been
+ * filled at group creation time as queue was being instantiated
+ * and driver had not attached a device yet
+ */
+ if (bdi->dev && dev_name(bdi->dev)) {
+ sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
+ tg->blkg.dev = MKDEV(major, minor);
+ }
+}
+
+static void throtl_init_add_tg_lists(struct throtl_data *td,
+ struct throtl_grp *tg, struct blkio_cgroup *blkcg)
+{
+ __throtl_tg_fill_dev_details(td, tg);
+
/* Add group onto cgroup list */
- sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
blkiocg_add_blkio_group(blkcg, &tg->blkg, (void *)td,
- MKDEV(major, minor), BLKIO_POLICY_THROTL);
+ tg->blkg.dev, BLKIO_POLICY_THROTL);

tg->bps[READ] = blkcg_get_read_bps(blkcg, tg->blkg.dev);
tg->bps[WRITE] = blkcg_get_write_bps(blkcg, tg->blkg.dev);
@@ -225,8 +243,6 @@ throtl_grp *throtl_find_tg(struct throtl_data *td, struct blkio_cgroup *blkcg)
{
struct throtl_grp *tg = NULL;
void *key = td;
- struct backing_dev_info *bdi = &td->queue->backing_dev_info;
- unsigned int major, minor;

/*
* This is the common case when there are no blkio cgroups.
@@ -237,12 +253,7 @@ throtl_grp *throtl_find_tg(struct throtl_data *td, struct blkio_cgroup *blkcg)
else
tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key));

- /* Fill in device details for root group */
- if (tg && !tg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
- sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
- tg->blkg.dev = MKDEV(major, minor);
- }
-
+ __throtl_tg_fill_dev_details(td, tg);
return tg;
}

--
1.7.4.4