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>

2 files changed, 13 insertions, 11 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 71894e143b91..a2648153691f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -387,7 +387,7 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
                 if (!list_empty(&q->queue_head) && q->request_fn)
                         __blk_run_queue(q);
 
-                drain |= q->rq.elvpriv;
+                drain |= q->nr_rqs_elvpriv;
 
                 /*
                  * Unfortunately, requests are queued at and tracked from
@@ -397,7 +397,7 @@ void blk_drain_queue(struct request_queue *q, bool drain_all)
                 if (drain_all) {
                         drain |= !list_empty(&q->queue_head);
                         for (i = 0; i < 2; i++) {
-                                drain |= q->rq.count[i];
+                                drain |= q->nr_rqs[i];
                                 drain |= q->in_flight[i];
                                 drain |= !list_empty(&q->flush_queue[i]);
                         }
@@ -526,7 +526,6 @@ static int blk_init_free_list(struct request_queue *q)
 
         rl->count[BLK_RW_SYNC] = rl->count[BLK_RW_ASYNC] = 0;
         rl->starved[BLK_RW_SYNC] = rl->starved[BLK_RW_ASYNC] = 0;
-        rl->elvpriv = 0;
         init_waitqueue_head(&rl->wait[BLK_RW_SYNC]);
         init_waitqueue_head(&rl->wait[BLK_RW_ASYNC]);
 
@@ -791,9 +790,10 @@ static void freed_request(struct request_queue *q, unsigned int flags)
         struct request_list *rl = &q->rq;
         int sync = rw_is_sync(flags);
 
+        q->nr_rqs[sync]--;
         rl->count[sync]--;
         if (flags & REQ_ELVPRIV)
-                rl->elvpriv--;
+                q->nr_rqs_elvpriv--;
 
         __freed_request(q, sync);
 
@@ -902,6 +902,7 @@ static struct request *__get_request(struct request_queue *q, int rw_flags,
         if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
                 return NULL;
 
+        q->nr_rqs[is_sync]++;
         rl->count[is_sync]++;
         rl->starved[is_sync] = 0;
 
@@ -917,7 +918,7 @@ static struct request *__get_request(struct request_queue *q, int rw_flags,
          */
         if (blk_rq_should_init_elevator(bio) && !blk_queue_bypass(q)) {
                 rw_flags |= REQ_ELVPRIV;
-                rl->elvpriv++;
+                q->nr_rqs_elvpriv++;
                 if (et->icq_cache && ioc)
                         icq = ioc_lookup_icq(ioc, q);
         }
@@ -978,7 +979,7 @@ fail_elvpriv:
         rq->elv.icq = NULL;
 
         spin_lock_irq(q->queue_lock);
-        rl->elvpriv--;
+        q->nr_rqs_elvpriv--;
         spin_unlock_irq(q->queue_lock);
         goto out;
 
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