blkio: Core implementation of throttle policy

o Actual implementation of throttling policy in block layer. Currently it
  implements READ and WRITE bytes per second throttling logic. IOPS throttling
  comes in later patches.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

2 files changed, 27 insertions, 0 deletions

diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index ca83a97c9715..10a0c291b55a 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -130,6 +130,8 @@ enum rq_flag_bits {
         /* bio only flags */
         __REQ_UNPLUG,           /* unplug the immediately after submission */
         __REQ_RAHEAD,           /* read ahead, can fail anytime */
+        __REQ_THROTTLED,        /* This bio has already been subjected to
+                                 * throttling rules. Don't do it again. */
 
         /* request only flags */
         __REQ_SORTED,           /* elevator knows about this request */
@@ -172,6 +174,7 @@ enum rq_flag_bits {
 
 #define REQ_UNPLUG              (1 << __REQ_UNPLUG)
 #define REQ_RAHEAD              (1 << __REQ_RAHEAD)
+#define REQ_THROTTLED           (1 << __REQ_THROTTLED)
 
 #define REQ_SORTED              (1 << __REQ_SORTED)
 #define REQ_SOFTBARRIER         (1 << __REQ_SOFTBARRIER)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 780824edac16..1341df5806df 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -371,6 +371,11 @@ struct request_queue
 #if defined(CONFIG_BLK_DEV_BSG)
         struct bsg_class_device bsg_dev;
 #endif
+
+#ifdef CONFIG_BLK_DEV_THROTTLING
+        /* Throttle data */
+        struct throtl_data *td;
+#endif
 };
 
 #define QUEUE_FLAG_CLUSTER      0       /* cluster several segments into 1 */
@@ -1131,6 +1136,7 @@ static inline void put_dev_sector(Sector p)
 
 struct work_struct;
 int kblockd_schedule_work(struct request_queue *q, struct work_struct *work);
+int kblockd_schedule_delayed_work(struct request_queue *q, struct delayed_work *dwork, unsigned long delay);
 
 #ifdef CONFIG_BLK_CGROUP
 /*
@@ -1174,6 +1180,24 @@ static inline uint64_t rq_io_start_time_ns(struct request *req)
 }
 #endif
 
+#ifdef CONFIG_BLK_DEV_THROTTLING
+extern int blk_throtl_init(struct request_queue *q);
+extern void blk_throtl_exit(struct request_queue *q);
+extern int blk_throtl_bio(struct request_queue *q, struct bio **bio);
+extern void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay);
+extern void throtl_shutdown_timer_wq(struct request_queue *q);
+#else /* CONFIG_BLK_DEV_THROTTLING */
+static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio)
+{
+        return 0;
+}
+
+static inline int blk_throtl_init(struct request_queue *q) { return 0; }
+static inline int blk_throtl_exit(struct request_queue *q) { return 0; }
+static inline void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay) {}
+static inline void throtl_shutdown_timer_wq(struct request_queue *q) {}
+#endif /* CONFIG_BLK_DEV_THROTTLING */
+
 #define MODULE_ALIAS_BLOCKDEV(major,minor) \
         MODULE_ALIAS("block-major-" __stringify(major) "-" __stringify(minor))
 #define MODULE_ALIAS_BLOCKDEV_MAJOR(major) \