block: add q->nr_rqs[] and move q->rq.elvpriv to q->nr_rqs_elvpriv

Add q->nr_rqs[] which currently behaves the same as q->rq.count[] and
move q->rq.elvpriv to q->nr_rqs_elvpriv.  blk_drain_queue() is updated
to use q->nr_rqs[] instead of q->rq.count[].

These counters separates queue-wide request statistics from the
request list and allow implementation of per-queue request allocation.

While at it, properly indent fields of struct request_list.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 6 insertions, 5 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 07954b05b86c..7e44ed93f84b 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -51,11 +51,10 @@ struct request_list {
          * count[], starved[], and wait[] are indexed by
          * BLK_RW_SYNC/BLK_RW_ASYNC
          */
-        int count[2];
-        int starved[2];
-        int elvpriv;
-        mempool_t *rq_pool;
-        wait_queue_head_t wait[2];
+        int                     count[2];
+        int                     starved[2];
+        mempool_t               *rq_pool;
+        wait_queue_head_t       wait[2];
 };
 
 /*
@@ -282,6 +281,8 @@ struct request_queue {
         struct list_head        queue_head;
         struct request          *last_merge;
         struct elevator_queue   *elevator;
+        int                     nr_rqs[2];      /* # allocated [a]sync rqs */
+        int                     nr_rqs_elvpriv; /* # allocated rqs w/ elvpriv */
 
         /*
          * the queue request freelist, one for reads and one for writes