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Subject[PATCH 1/4] blkcg: add blkcg->id
Date
Add 64bit unique id to blkcg.  This will be used by policies which
want blkcg identity test to tell whether the associated blkcg has
changed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
---
block/blk-cgroup.c | 3 +++
block/blk-cgroup.h | 3 +++
2 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index b15a517..30e0730 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -19,6 +19,7 @@
#include <linux/slab.h>
#include <linux/genhd.h>
#include <linux/delay.h>
+#include <linux/atomic.h>
#include "blk-cgroup.h"
#include "blk.h"

@@ -1622,6 +1623,7 @@ static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
static struct cgroup_subsys_state *
blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
{
+ static atomic64_t id_seq = ATOMIC64_INIT(0);
struct blkio_cgroup *blkcg;
struct cgroup *parent = cgroup->parent;

@@ -1635,6 +1637,7 @@ blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
return ERR_PTR(-ENOMEM);

blkcg->weight = BLKIO_WEIGHT_DEFAULT;
+ blkcg->id = atomic64_inc_return(&id_seq); /* root is 0, start from 1 */
done:
spin_lock_init(&blkcg->lock);
INIT_HLIST_HEAD(&blkcg->blkg_list);
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 9df5ab0..1cb8f76 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -116,6 +116,9 @@ struct blkio_cgroup {
unsigned int weight;
spinlock_t lock;
struct hlist_head blkg_list;
+
+ /* for policies to test whether associated blkcg has changed */
+ uint64_t id;
};

struct blkio_group_stats {
--
1.7.7.3


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