blk-throttle: move bio_lists[] and friends to throtl_service_queue

throtl_service_queues will eventually form a tree which is anchored at
throtl_data->service_queue and queue bios will climb the tree to the
top service_queue to be executed.

This patch moves bio_lists[] and nr_queued[] from throtl_grp to its
service_queue to prepare for that.  As currently only the
throtl_data->service_queue is in use, this patch just ends up moving
throtl_grp->bio_lists[] and ->nr_queued[] to
throtl_grp->service_queue.bio_lists[] and ->nr_queued[] without making
any functional differences.

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

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 7340440..6f57f94 100644 (file)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -27,6 +27,17 @@ static struct blkcg_policy blkcg_policy_throtl;
 static struct workqueue_struct *kthrotld_workqueue;
 
 struct throtl_service_queue {
+       /*
+        * Bios queued directly to this service_queue or dispatched from
+        * children throtl_grp's.
+        */
+       struct bio_list         bio_lists[2];   /* queued bios [READ/WRITE] */
+       unsigned int            nr_queued[2];   /* number of queued bios */
+
+       /*
+        * RB tree of active children throtl_grp's, which are sorted by
+        * their ->disptime.
+        */
        struct rb_root          pending_tree;   /* RB tree of active tgs */
        struct rb_node          *first_pending; /* first node in the tree */
        unsigned int            nr_pending;     /* # queued in the tree */
@@ -69,12 +80,6 @@ struct throtl_grp {
 
        unsigned int flags;
 
-       /* Two lists for READ and WRITE */
-       struct bio_list bio_lists[2];
-
-       /* Number of queued bios on READ and WRITE lists */
-       unsigned int nr_queued[2];
-
        /* bytes per second rate limits */
        uint64_t bps[2];
 
@@ -193,6 +198,8 @@ alloc_stats:
 /* init a service_queue, assumes the caller zeroed it */
 static void throtl_service_queue_init(struct throtl_service_queue *sq)
 {
+       bio_list_init(&sq->bio_lists[0]);
+       bio_list_init(&sq->bio_lists[1]);
        sq->pending_tree = RB_ROOT;
 }
 
@@ -204,8 +211,6 @@ static void throtl_pd_init(struct blkcg_gq *blkg)
        throtl_service_queue_init(&tg->service_queue);
        RB_CLEAR_NODE(&tg->rb_node);
        tg->td = blkg->q->td;
-       bio_list_init(&tg->bio_lists[0]);
-       bio_list_init(&tg->bio_lists[1]);
 
        tg->bps[READ] = -1;
        tg->bps[WRITE] = -1;
@@ -624,7 +629,8 @@ static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
         * this function with a different bio if there are other bios
         * queued.
         */
-       BUG_ON(tg->nr_queued[rw] && bio != bio_list_peek(&tg->bio_lists[rw]));
+       BUG_ON(tg->service_queue.nr_queued[rw] &&
+              bio != bio_list_peek(&tg->service_queue.bio_lists[rw]));
 
        /* If tg->bps = -1, then BW is unlimited */
        if (tg->bps[rw] == -1 && tg->iops[rw] == -1) {
@@ -703,12 +709,13 @@ static void throtl_charge_bio(struct throtl_grp *tg, struct bio *bio)
 static void throtl_add_bio_tg(struct bio *bio, struct throtl_grp *tg,
                              struct throtl_service_queue *parent_sq)
 {
+       struct throtl_service_queue *sq = &tg->service_queue;
        bool rw = bio_data_dir(bio);
 
-       bio_list_add(&tg->bio_lists[rw], bio);
+       bio_list_add(&sq->bio_lists[rw], bio);
        /* Take a bio reference on tg */
        blkg_get(tg_to_blkg(tg));
-       tg->nr_queued[rw]++;
+       sq->nr_queued[rw]++;
        tg->td->nr_queued[rw]++;
        throtl_enqueue_tg(tg, parent_sq);
 }
@@ -716,13 +723,14 @@ static void throtl_add_bio_tg(struct bio *bio, struct throtl_grp *tg,
 static void tg_update_disptime(struct throtl_grp *tg,
                               struct throtl_service_queue *parent_sq)
 {
+       struct throtl_service_queue *sq = &tg->service_queue;
        unsigned long read_wait = -1, write_wait = -1, min_wait = -1, disptime;
        struct bio *bio;
 
-       if ((bio = bio_list_peek(&tg->bio_lists[READ])))
+       if ((bio = bio_list_peek(&sq->bio_lists[READ])))
                tg_may_dispatch(tg, bio, &read_wait);
 
-       if ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
+       if ((bio = bio_list_peek(&sq->bio_lists[WRITE])))
                tg_may_dispatch(tg, bio, &write_wait);
 
        min_wait = min(read_wait, write_wait);
@@ -737,10 +745,11 @@ static void tg_update_disptime(struct throtl_grp *tg,
 static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw,
                                struct bio_list *bl)
 {
+       struct throtl_service_queue *sq = &tg->service_queue;
        struct bio *bio;
 
-       bio = bio_list_pop(&tg->bio_lists[rw]);
-       tg->nr_queued[rw]--;
+       bio = bio_list_pop(&sq->bio_lists[rw]);
+       sq->nr_queued[rw]--;
        /* Drop bio reference on blkg */
        blkg_put(tg_to_blkg(tg));
 
@@ -756,6 +765,7 @@ static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw,
 
 static int throtl_dispatch_tg(struct throtl_grp *tg, struct bio_list *bl)
 {
+       struct throtl_service_queue *sq = &tg->service_queue;
        unsigned int nr_reads = 0, nr_writes = 0;
        unsigned int max_nr_reads = throtl_grp_quantum*3/4;
        unsigned int max_nr_writes = throtl_grp_quantum - max_nr_reads;
@@ -763,7 +773,7 @@ static int throtl_dispatch_tg(struct throtl_grp *tg, struct bio_list *bl)
 
        /* Try to dispatch 75% READS and 25% WRITES */
 
-       while ((bio = bio_list_peek(&tg->bio_lists[READ])) &&
+       while ((bio = bio_list_peek(&sq->bio_lists[READ])) &&
               tg_may_dispatch(tg, bio, NULL)) {
 
                tg_dispatch_one_bio(tg, bio_data_dir(bio), bl);
@@ -773,7 +783,7 @@ static int throtl_dispatch_tg(struct throtl_grp *tg, struct bio_list *bl)
                        break;
        }
 
-       while ((bio = bio_list_peek(&tg->bio_lists[WRITE])) &&
+       while ((bio = bio_list_peek(&sq->bio_lists[WRITE])) &&
               tg_may_dispatch(tg, bio, NULL)) {
 
                tg_dispatch_one_bio(tg, bio_data_dir(bio), bl);
@@ -790,10 +800,10 @@ static int throtl_select_dispatch(struct throtl_service_queue *parent_sq,
                                  struct bio_list *bl)
 {
        unsigned int nr_disp = 0;
-       struct throtl_grp *tg;
 
        while (1) {
-               tg = throtl_rb_first(parent_sq);
+               struct throtl_grp *tg = throtl_rb_first(parent_sq);
+               struct throtl_service_queue *sq = &tg->service_queue;
 
                if (!tg)
                        break;
@@ -805,7 +815,7 @@ static int throtl_select_dispatch(struct throtl_service_queue *parent_sq,
 
                nr_disp += throtl_dispatch_tg(tg, bl);
 
-               if (tg->nr_queued[0] || tg->nr_queued[1])
+               if (sq->nr_queued[0] || sq->nr_queued[1])
                        tg_update_disptime(tg, parent_sq);
 
                if (nr_disp >= throtl_quantum)
@@ -1043,6 +1053,7 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
 {
        struct throtl_data *td = q->td;
        struct throtl_grp *tg;
+       struct throtl_service_queue *sq;
        bool rw = bio_data_dir(bio), update_disptime = true;
        struct blkcg *blkcg;
        bool throttled = false;
@@ -1077,7 +1088,9 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
        if (unlikely(!tg))
                goto out_unlock;
 
-       if (tg->nr_queued[rw]) {
+       sq = &tg->service_queue;
+
+       if (sq->nr_queued[rw]) {
                /*
                 * There is already another bio queued in same dir. No
                 * need to update dispatch time.
@@ -1112,7 +1125,7 @@ queue_bio:
                        rw == READ ? 'R' : 'W',
                        tg->bytes_disp[rw], bio->bi_size, tg->bps[rw],
                        tg->io_disp[rw], tg->iops[rw],
-                       tg->nr_queued[READ], tg->nr_queued[WRITE]);
+                       sq->nr_queued[READ], sq->nr_queued[WRITE]);
 
        bio_associate_current(bio);
        throtl_add_bio_tg(bio, tg, &q->td->service_queue);
@@ -1151,11 +1164,13 @@ void blk_throtl_drain(struct request_queue *q)
        bio_list_init(&bl);
 
        while ((tg = throtl_rb_first(parent_sq))) {
+               struct throtl_service_queue *sq = &tg->service_queue;
+
                throtl_dequeue_tg(tg, parent_sq);
 
-               while ((bio = bio_list_peek(&tg->bio_lists[READ])))
+               while ((bio = bio_list_peek(&sq->bio_lists[READ])))
                        tg_dispatch_one_bio(tg, bio_data_dir(bio), &bl);
-               while ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
+               while ((bio = bio_list_peek(&sq->bio_lists[WRITE])))
                        tg_dispatch_one_bio(tg, bio_data_dir(bio), &bl);
        }
        spin_unlock_irq(q->queue_lock);