blk-throttle: add backlink pointer from throtl_grp to throtl_data

Add throtl_grp->td so that the td (throtl_data) a given tg
(throtl_grp) belongs to can be determined, and remove @td argument
from functions which take both @td and @tg as the former now can be
determined from the latter.

This generally simplifies the code and removes a number of cases where
@td is passed as an argument without being actually used.  This will
also help hierarchy support implementation.

While at it, in multi-line conditions, move the logical operators
leading broken lines to the end of the previous line.

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 e8ef43d..a489391 100644 (file)
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -57,6 +57,9 @@ struct throtl_grp {
        /* active throtl group service_queue member */
        struct rb_node rb_node;
 
+       /* throtl_data this group belongs to */
+       struct throtl_data *td;
+
        /*
         * Dispatch time in jiffies. This is the estimated time when group
         * will unthrottle and is ready to dispatch more bio. It is used as
@@ -140,11 +143,11 @@ static inline struct throtl_grp *td_root_tg(struct throtl_data *td)
        return blkg_to_tg(td->queue->root_blkg);
 }
 
-#define throtl_log_tg(td, tg, fmt, args...)    do {                    \
+#define throtl_log_tg(tg, fmt, args...)        do {                            \
        char __pbuf[128];                                               \
                                                                        \
        blkg_path(tg_to_blkg(tg), __pbuf, sizeof(__pbuf));              \
-       blk_add_trace_msg((td)->queue, "throtl %s " fmt, __pbuf, ##args); \
+       blk_add_trace_msg((tg)->td->queue, "throtl %s " fmt, __pbuf, ##args); \
 } while (0)
 
 #define throtl_log(td, fmt, args...)   \
@@ -193,6 +196,7 @@ static void throtl_pd_init(struct blkcg_gq *blkg)
        unsigned long flags;
 
        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]);
 
@@ -401,36 +405,34 @@ static void throtl_schedule_next_dispatch(struct throtl_data *td)
                throtl_schedule_delayed_work(td, sq->first_pending_disptime - jiffies);
 }
 
-static inline void
-throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
+static inline void throtl_start_new_slice(struct throtl_grp *tg, bool rw)
 {
        tg->bytes_disp[rw] = 0;
        tg->io_disp[rw] = 0;
        tg->slice_start[rw] = jiffies;
        tg->slice_end[rw] = jiffies + throtl_slice;
-       throtl_log_tg(td, tg, "[%c] new slice start=%lu end=%lu jiffies=%lu",
+       throtl_log_tg(tg, "[%c] new slice start=%lu end=%lu jiffies=%lu",
                        rw == READ ? 'R' : 'W', tg->slice_start[rw],
                        tg->slice_end[rw], jiffies);
 }
 
-static inline void throtl_set_slice_end(struct throtl_data *td,
-               struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
+static inline void throtl_set_slice_end(struct throtl_grp *tg, bool rw,
+                                       unsigned long jiffy_end)
 {
        tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
 }
 
-static inline void throtl_extend_slice(struct throtl_data *td,
-               struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
+static inline void throtl_extend_slice(struct throtl_grp *tg, bool rw,
+                                      unsigned long jiffy_end)
 {
        tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
-       throtl_log_tg(td, tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu",
+       throtl_log_tg(tg, "[%c] extend slice start=%lu end=%lu jiffies=%lu",
                        rw == READ ? 'R' : 'W', tg->slice_start[rw],
                        tg->slice_end[rw], jiffies);
 }
 
 /* Determine if previously allocated or extended slice is complete or not */
-static bool
-throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw)
+static bool throtl_slice_used(struct throtl_grp *tg, bool rw)
 {
        if (time_in_range(jiffies, tg->slice_start[rw], tg->slice_end[rw]))
                return 0;
@@ -439,8 +441,7 @@ throtl_slice_used(struct throtl_data *td, struct throtl_grp *tg, bool rw)
 }
 
 /* Trim the used slices and adjust slice start accordingly */
-static inline void
-throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
+static inline void throtl_trim_slice(struct throtl_grp *tg, bool rw)
 {
        unsigned long nr_slices, time_elapsed, io_trim;
        u64 bytes_trim, tmp;
@@ -452,7 +453,7 @@ throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
         * renewed. Don't try to trim the slice if slice is used. A new
         * slice will start when appropriate.
         */
-       if (throtl_slice_used(td, tg, rw))
+       if (throtl_slice_used(tg, rw))
                return;
 
        /*
@@ -463,7 +464,7 @@ throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
         * is bad because it does not allow new slice to start.
         */
 
-       throtl_set_slice_end(td, tg, rw, jiffies + throtl_slice);
+       throtl_set_slice_end(tg, rw, jiffies + throtl_slice);
 
        time_elapsed = jiffies - tg->slice_start[rw];
 
@@ -492,14 +493,14 @@ throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
 
        tg->slice_start[rw] += nr_slices * throtl_slice;
 
-       throtl_log_tg(td, tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu"
+       throtl_log_tg(tg, "[%c] trim slice nr=%lu bytes=%llu io=%lu"
                        " start=%lu end=%lu jiffies=%lu",
                        rw == READ ? 'R' : 'W', nr_slices, bytes_trim, io_trim,
                        tg->slice_start[rw], tg->slice_end[rw], jiffies);
 }
 
-static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg,
-               struct bio *bio, unsigned long *wait)
+static bool tg_with_in_iops_limit(struct throtl_grp *tg, struct bio *bio,
+                                 unsigned long *wait)
 {
        bool rw = bio_data_dir(bio);
        unsigned int io_allowed;
@@ -548,8 +549,8 @@ static bool tg_with_in_iops_limit(struct throtl_data *td, struct throtl_grp *tg,
        return 0;
 }
 
-static bool tg_with_in_bps_limit(struct throtl_data *td, struct throtl_grp *tg,
-               struct bio *bio, unsigned long *wait)
+static bool tg_with_in_bps_limit(struct throtl_grp *tg, struct bio *bio,
+                                unsigned long *wait)
 {
        bool rw = bio_data_dir(bio);
        u64 bytes_allowed, extra_bytes, tmp;
@@ -600,8 +601,8 @@ static bool tg_no_rule_group(struct throtl_grp *tg, bool rw) {
  * Returns whether one can dispatch a bio or not. Also returns approx number
  * of jiffies to wait before this bio is with-in IO rate and can be dispatched
  */
-static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,
-                               struct bio *bio, unsigned long *wait)
+static bool tg_may_dispatch(struct throtl_grp *tg, struct bio *bio,
+                           unsigned long *wait)
 {
        bool rw = bio_data_dir(bio);
        unsigned long bps_wait = 0, iops_wait = 0, max_wait = 0;
@@ -626,15 +627,15 @@ static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,
         * existing slice to make sure it is at least throtl_slice interval
         * long since now.
         */
-       if (throtl_slice_used(td, tg, rw))
-               throtl_start_new_slice(td, tg, rw);
+       if (throtl_slice_used(tg, rw))
+               throtl_start_new_slice(tg, rw);
        else {
                if (time_before(tg->slice_end[rw], jiffies + throtl_slice))
-                       throtl_extend_slice(td, tg, rw, jiffies + throtl_slice);
+                       throtl_extend_slice(tg, rw, jiffies + throtl_slice);
        }
 
-       if (tg_with_in_bps_limit(td, tg, bio, &bps_wait)
-           && tg_with_in_iops_limit(td, tg, bio, &iops_wait)) {
+       if (tg_with_in_bps_limit(tg, bio, &bps_wait) &&
+           tg_with_in_iops_limit(tg, bio, &iops_wait)) {
                if (wait)
                        *wait = 0;
                return 1;
@@ -646,7 +647,7 @@ static bool tg_may_dispatch(struct throtl_data *td, struct throtl_grp *tg,
                *wait = max_wait;
 
        if (time_before(tg->slice_end[rw], jiffies + max_wait))
-               throtl_extend_slice(td, tg, rw, jiffies + max_wait);
+               throtl_extend_slice(tg, rw, jiffies + max_wait);
 
        return 0;
 }
@@ -707,10 +708,10 @@ static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg)
        struct bio *bio;
 
        if ((bio = bio_list_peek(&tg->bio_lists[READ])))
-               tg_may_dispatch(td, tg, bio, &read_wait);
+               tg_may_dispatch(tg, bio, &read_wait);
 
        if ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
-               tg_may_dispatch(td, tg, bio, &write_wait);
+               tg_may_dispatch(tg, bio, &write_wait);
 
        min_wait = min(read_wait, write_wait);
        disptime = jiffies + min_wait;
@@ -721,8 +722,8 @@ static void tg_update_disptime(struct throtl_data *td, struct throtl_grp *tg)
        throtl_enqueue_tg(td, tg);
 }
 
-static void tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg,
-                               bool rw, struct bio_list *bl)
+static void tg_dispatch_one_bio(struct throtl_grp *tg, bool rw,
+                               struct bio_list *bl)
 {
        struct bio *bio;
 
@@ -731,18 +732,17 @@ static void tg_dispatch_one_bio(struct throtl_data *td, struct throtl_grp *tg,
        /* Drop bio reference on blkg */
        blkg_put(tg_to_blkg(tg));
 
-       BUG_ON(td->nr_queued[rw] <= 0);
-       td->nr_queued[rw]--;
+       BUG_ON(tg->td->nr_queued[rw] <= 0);
+       tg->td->nr_queued[rw]--;
 
        throtl_charge_bio(tg, bio);
        bio_list_add(bl, bio);
        bio->bi_rw |= REQ_THROTTLED;
 
-       throtl_trim_slice(td, tg, rw);
+       throtl_trim_slice(tg, rw);
 }
 
-static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg,
-                               struct bio_list *bl)
+static int throtl_dispatch_tg(struct throtl_grp *tg, struct bio_list *bl)
 {
        unsigned int nr_reads = 0, nr_writes = 0;
        unsigned int max_nr_reads = throtl_grp_quantum*3/4;
@@ -751,20 +751,20 @@ static int throtl_dispatch_tg(struct throtl_data *td, struct throtl_grp *tg,
 
        /* Try to dispatch 75% READS and 25% WRITES */
 
-       while ((bio = bio_list_peek(&tg->bio_lists[READ]))
-               && tg_may_dispatch(td, tg, bio, NULL)) {
+       while ((bio = bio_list_peek(&tg->bio_lists[READ])) &&
+              tg_may_dispatch(tg, bio, NULL)) {
 
-               tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);
+               tg_dispatch_one_bio(tg, bio_data_dir(bio), bl);
                nr_reads++;
 
                if (nr_reads >= max_nr_reads)
                        break;
        }
 
-       while ((bio = bio_list_peek(&tg->bio_lists[WRITE]))
-               && tg_may_dispatch(td, tg, bio, NULL)) {
+       while ((bio = bio_list_peek(&tg->bio_lists[WRITE])) &&
+              tg_may_dispatch(tg, bio, NULL)) {
 
-               tg_dispatch_one_bio(td, tg, bio_data_dir(bio), bl);
+               tg_dispatch_one_bio(tg, bio_data_dir(bio), bl);
                nr_writes++;
 
                if (nr_writes >= max_nr_writes)
@@ -791,7 +791,7 @@ static int throtl_select_dispatch(struct throtl_data *td, struct bio_list *bl)
 
                throtl_dequeue_tg(td, tg);
 
-               nr_disp += throtl_dispatch_tg(td, tg, bl);
+               nr_disp += throtl_dispatch_tg(tg, bl);
 
                if (tg->nr_queued[0] || tg->nr_queued[1])
                        tg_update_disptime(td, tg);
@@ -933,7 +933,7 @@ static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf,
        else
                *(unsigned int *)((void *)tg + cft->private) = ctx.v;
 
-       throtl_log_tg(td, tg, "limit change rbps=%llu wbps=%llu riops=%u wiops=%u",
+       throtl_log_tg(tg, "limit change rbps=%llu wbps=%llu riops=%u wiops=%u",
                      tg->bps[READ], tg->bps[WRITE],
                      tg->iops[READ], tg->iops[WRITE]);
 
@@ -945,8 +945,8 @@ static int tg_set_conf(struct cgroup *cgrp, struct cftype *cft, const char *buf,
         * that a group's limit are dropped suddenly and we don't want to
         * account recently dispatched IO with new low rate.
         */
-       throtl_start_new_slice(td, tg, 0);
-       throtl_start_new_slice(td, tg, 1);
+       throtl_start_new_slice(tg, 0);
+       throtl_start_new_slice(tg, 1);
 
        if (tg->flags & THROTL_TG_PENDING) {
                tg_update_disptime(td, tg);
@@ -1076,7 +1076,7 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
        }
 
        /* Bio is with-in rate limit of group */
-       if (tg_may_dispatch(td, tg, bio, NULL)) {
+       if (tg_may_dispatch(tg, bio, NULL)) {
                throtl_charge_bio(tg, bio);
 
                /*
@@ -1090,12 +1090,12 @@ bool blk_throtl_bio(struct request_queue *q, struct bio *bio)
                 *
                 * So keep on trimming slice even if bio is not queued.
                 */
-               throtl_trim_slice(td, tg, rw);
+               throtl_trim_slice(tg, rw);
                goto out_unlock;
        }
 
 queue_bio:
-       throtl_log_tg(td, tg, "[%c] bio. bdisp=%llu sz=%u bps=%llu"
+       throtl_log_tg(tg, "[%c] bio. bdisp=%llu sz=%u bps=%llu"
                        " iodisp=%u iops=%u queued=%d/%d",
                        rw == READ ? 'R' : 'W',
                        tg->bytes_disp[rw], bio->bi_size, tg->bps[rw],
@@ -1142,9 +1142,9 @@ void blk_throtl_drain(struct request_queue *q)
                throtl_dequeue_tg(td, tg);
 
                while ((bio = bio_list_peek(&tg->bio_lists[READ])))
-                       tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
+                       tg_dispatch_one_bio(tg, bio_data_dir(bio), &bl);
                while ((bio = bio_list_peek(&tg->bio_lists[WRITE])))
-                       tg_dispatch_one_bio(td, tg, bio_data_dir(bio), &bl);
+                       tg_dispatch_one_bio(tg, bio_data_dir(bio), &bl);
        }
        spin_unlock_irq(q->queue_lock);