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>

diff --git a/block/blk-core.c b/block/blk-core.c
index 71894e1..a264815 100644 (file)
--- 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 07954b0..7e44ed9 100644 (file)
--- 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