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-rw-r--r--block/blk-cgroup.c69
1 files changed, 51 insertions, 18 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index b6f20be0fc78..5d21027b1faf 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1362,7 +1362,7 @@ int blkcg_activate_policy(struct request_queue *q,
const struct blkcg_policy *pol)
{
struct blkg_policy_data *pd_prealloc = NULL;
- struct blkcg_gq *blkg;
+ struct blkcg_gq *blkg, *pinned_blkg = NULL;
int ret;
if (blkcg_policy_enabled(q, pol))
@@ -1370,49 +1370,82 @@ int blkcg_activate_policy(struct request_queue *q,
if (queue_is_mq(q))
blk_mq_freeze_queue(q);
-pd_prealloc:
- if (!pd_prealloc) {
- pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q, &blkcg_root);
- if (!pd_prealloc) {
- ret = -ENOMEM;
- goto out_bypass_end;
- }
- }
-
+retry:
spin_lock_irq(&q->queue_lock);
- /* blkg_list is pushed at the head, reverse walk to init parents first */
+ /* blkg_list is pushed at the head, reverse walk to allocate parents first */
list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) {
struct blkg_policy_data *pd;
if (blkg->pd[pol->plid])
continue;
- pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q, &blkcg_root);
- if (!pd)
- swap(pd, pd_prealloc);
+ /* If prealloc matches, use it; otherwise try GFP_NOWAIT */
+ if (blkg == pinned_blkg) {
+ pd = pd_prealloc;
+ pd_prealloc = NULL;
+ } else {
+ pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q,
+ blkg->blkcg);
+ }
+
if (!pd) {
+ /*
+ * GFP_NOWAIT failed. Free the existing one and
+ * prealloc for @blkg w/ GFP_KERNEL.
+ */
+ if (pinned_blkg)
+ blkg_put(pinned_blkg);
+ blkg_get(blkg);
+ pinned_blkg = blkg;
+
spin_unlock_irq(&q->queue_lock);
- goto pd_prealloc;
+
+ if (pd_prealloc)
+ pol->pd_free_fn(pd_prealloc);
+ pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q,
+ blkg->blkcg);
+ if (pd_prealloc)
+ goto retry;
+ else
+ goto enomem;
}
blkg->pd[pol->plid] = pd;
pd->blkg = blkg;
pd->plid = pol->plid;
- if (pol->pd_init_fn)
- pol->pd_init_fn(pd);
}
+ /* all allocated, init in the same order */
+ if (pol->pd_init_fn)
+ list_for_each_entry_reverse(blkg, &q->blkg_list, q_node)
+ pol->pd_init_fn(blkg->pd[pol->plid]);
+
__set_bit(pol->plid, q->blkcg_pols);
ret = 0;
spin_unlock_irq(&q->queue_lock);
-out_bypass_end:
+out:
if (queue_is_mq(q))
blk_mq_unfreeze_queue(q);
+ if (pinned_blkg)
+ blkg_put(pinned_blkg);
if (pd_prealloc)
pol->pd_free_fn(pd_prealloc);
return ret;
+
+enomem:
+ /* alloc failed, nothing's initialized yet, free everything */
+ spin_lock_irq(&q->queue_lock);
+ list_for_each_entry(blkg, &q->blkg_list, q_node) {
+ if (blkg->pd[pol->plid]) {
+ pol->pd_free_fn(blkg->pd[pol->plid]);
+ blkg->pd[pol->plid] = NULL;
+ }
+ }
+ spin_unlock_irq(&q->queue_lock);
+ ret = -ENOMEM;
+ goto out;
}
EXPORT_SYMBOL_GPL(blkcg_activate_policy);