blkcg: add blkcg->id
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>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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 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 @@
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);