blkio: Export disk time and sectors used by a group to user space

o Export disk time and sector used by a group to user space through cgroup
  interface.

o Also export a "dequeue" interface to cgroup which keeps track of how many
  a times a group was deleted from service tree. Helps in debugging.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 63 insertions, 1 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 6bc99a3865b0..4ef78d35cbd2 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -11,6 +11,8 @@
  *                    Nauman Rafique <nauman@google.com>
  */
 #include <linux/ioprio.h>
+#include <linux/seq_file.h>
+#include <linux/kdev_t.h>
 #include "blk-cgroup.h"
 
 extern void cfq_unlink_blkio_group(void *, struct blkio_group *);
@@ -23,8 +25,15 @@ struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
                             struct blkio_cgroup, css);
 }
 
+void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
+                        unsigned long time, unsigned long sectors)
+{
+        blkg->time += time;
+        blkg->sectors += sectors;
+}
+
 void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
-                                struct blkio_group *blkg, void *key)
+                        struct blkio_group *blkg, void *key, dev_t dev)
 {
         unsigned long flags;
 
@@ -37,6 +46,7 @@ void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
         /* Need to take css reference ? */
         cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
 #endif
+        blkg->dev = dev;
 }
 
 static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
@@ -115,12 +125,64 @@ blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
         return 0;
 }
 
+#define SHOW_FUNCTION_PER_GROUP(__VAR)                                  \
+static int blkiocg_##__VAR##_read(struct cgroup *cgroup,                \
+                        struct cftype *cftype, struct seq_file *m)      \
+{                                                                       \
+        struct blkio_cgroup *blkcg;                                     \
+        struct blkio_group *blkg;                                       \
+        struct hlist_node *n;                                           \
+                                                                        \
+        if (!cgroup_lock_live_group(cgroup))                            \
+                return -ENODEV;                                         \
+                                                                        \
+        blkcg = cgroup_to_blkio_cgroup(cgroup);                         \
+        rcu_read_lock();                                                \
+        hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {\
+                if (blkg->dev)                                          \
+                        seq_printf(m, "%u:%u %lu\n", MAJOR(blkg->dev),  \
+                                 MINOR(blkg->dev), blkg->__VAR);        \
+        }                                                               \
+        rcu_read_unlock();                                              \
+        cgroup_unlock();                                                \
+        return 0;                                                       \
+}
+
+SHOW_FUNCTION_PER_GROUP(time);
+SHOW_FUNCTION_PER_GROUP(sectors);
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+SHOW_FUNCTION_PER_GROUP(dequeue);
+#endif
+#undef SHOW_FUNCTION_PER_GROUP
+
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group *blkg,
+                        unsigned long dequeue)
+{
+        blkg->dequeue += dequeue;
+}
+#endif
+
 struct cftype blkio_files[] = {
         {
                 .name = "weight",
                 .read_u64 = blkiocg_weight_read,
                 .write_u64 = blkiocg_weight_write,
         },
+        {
+                .name = "time",
+                .read_seq_string = blkiocg_time_read,
+        },
+        {
+                .name = "sectors",
+                .read_seq_string = blkiocg_sectors_read,
+        },
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+       {
+                .name = "dequeue",
+                .read_seq_string = blkiocg_dequeue_read,
+       },
+#endif
 };
 
 static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)