This function will be useful when we update weight from the soon-coming
per-device interface.
Signed-off-by: Fam Zheng <zhengfeiran@xxxxxxxxxxxxx>
Reviewed-by: Paolo Valente <paolo.valente@xxxxxxxxxx>
---
block/bfq-cgroup.c | 60 ++++++++++++++++++++++++----------------------
1 file changed, 32 insertions(+), 28 deletions(-)
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 0f6cd688924f..28e5a9241237 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -918,6 +918,36 @@ static int bfq_io_show_weight(struct seq_file *sf, void *v)
return 0;
}
+static void bfq_group_set_weight(struct bfq_group *bfqg, u64 weight)
+{
+ /*
+ * Setting the prio_changed flag of the entity
+ * to 1 with new_weight == weight would re-set
+ * the value of the weight to its ioprio mapping.
+ * Set the flag only if necessary.
+ */
+ if ((unsigned short)weight != bfqg->entity.new_weight) {
+ bfqg->entity.new_weight = (unsigned short)weight;
+ /*
+ * Make sure that the above new value has been
+ * stored in bfqg->entity.new_weight before
+ * setting the prio_changed flag. In fact,
+ * this flag may be read asynchronously (in
+ * critical sections protected by a different
+ * lock than that held here), and finding this
+ * flag set may cause the execution of the code
+ * for updating parameters whose value may
+ * depend also on bfqg->entity.new_weight (in
+ * __bfq_entity_update_weight_prio).
+ * This barrier makes sure that the new value
+ * of bfqg->entity.new_weight is correctly
+ * seen in that code.
+ */
+ smp_wmb();
+ bfqg->entity.prio_changed = 1;
+ }
+}
+
static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
struct cftype *cftype,
u64 val)
@@ -936,34 +966,8 @@ static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
struct bfq_group *bfqg = blkg_to_bfqg(blkg);
- if (!bfqg)
- continue;
- /*
- * Setting the prio_changed flag of the entity
- * to 1 with new_weight == weight would re-set
- * the value of the weight to its ioprio mapping.
- * Set the flag only if necessary.
- */
- if ((unsigned short)val != bfqg->entity.new_weight) {
- bfqg->entity.new_weight = (unsigned short)val;
- /*
- * Make sure that the above new value has been
- * stored in bfqg->entity.new_weight before
- * setting the prio_changed flag. In fact,
- * this flag may be read asynchronously (in
- * critical sections protected by a different
- * lock than that held here), and finding this
- * flag set may cause the execution of the code
- * for updating parameters whose value may
- * depend also on bfqg->entity.new_weight (in
- * __bfq_entity_update_weight_prio).
- * This barrier makes sure that the new value
- * of bfqg->entity.new_weight is correctly
- * seen in that code.
- */
- smp_wmb();
- bfqg->entity.prio_changed = 1;
- }
+ if (bfqg)
+ bfq_group_set_weight(bfqg, val);
}
spin_unlock_irq(&blkcg->lock);
--
2.22.1
