blkcg: move conf/stat file handling code to policies

blkcg conf/stat handling is convoluted in that details which belong to
specific policy implementations are all out in blkcg core and then
policies hook into core layer to access and manipulate confs and
stats.  This sadly achieves both inflexibility (confs/stats can't be
modified without messing with blkcg core) and complexity (all the
call-ins and call-backs).

The previous patches restructured conf and stat handling code such
that they can be separated out.  This patch relocates the file
handling part.  All conf/stat file handling code which belongs to
BLKIO_POLICY_PROP is moved to cfq-iosched.c and all
BKLIO_POLICY_THROTL code to blk-throtl.c.

The move is verbatim except for blkio_update_group_{weight|bps|iops}()
callbacks which relays conf changes to policies.  The configuration
settings are handled in policies themselves so the relaying isn't
necessary.  Conf setting functions are modified to directly call
per-policy update functions and the relaying mechanism is dropped.

Signed-off-by: Tejun Heo <tj@kernel.org>

1 files changed, 199 insertions, 3 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 8cca6161d0b..119e061a767 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -1058,8 +1058,7 @@ static void cfq_init_cfqg_base(struct cfq_group *cfqg)
 }
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
-static void cfq_update_blkio_group_weight(struct request_queue *q,
-                                          struct blkio_group *blkg,
+static void cfq_update_blkio_group_weight(struct blkio_group *blkg,
                                           unsigned int weight)
 {
         struct cfq_group *cfqg = blkg_to_cfqg(blkg);
@@ -1111,6 +1110,203 @@ static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
         cfqg_get(cfqg);
 }
 
+static u64 blkg_prfill_weight_device(struct seq_file *sf,
+                                     struct blkg_policy_data *pd, int off)
+{
+        if (!pd->conf.weight)
+                return 0;
+        return __blkg_prfill_u64(sf, pd, pd->conf.weight);
+}
+
+static int blkcg_print_weight_device(struct cgroup *cgrp, struct cftype *cft,
+                                     struct seq_file *sf)
+{
+        blkcg_print_blkgs(sf, cgroup_to_blkio_cgroup(cgrp),
+                          blkg_prfill_weight_device, BLKIO_POLICY_PROP, 0,
+                          false);
+        return 0;
+}
+
+static int blkcg_print_weight(struct cgroup *cgrp, struct cftype *cft,
+                              struct seq_file *sf)
+{
+        seq_printf(sf, "%u\n", cgroup_to_blkio_cgroup(cgrp)->weight);
+        return 0;
+}
+
+static int blkcg_set_weight_device(struct cgroup *cgrp, struct cftype *cft,
+                                   const char *buf)
+{
+        struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
+        struct blkg_policy_data *pd;
+        struct blkg_conf_ctx ctx;
+        int ret;
+
+        ret = blkg_conf_prep(blkcg, buf, &ctx);
+        if (ret)
+                return ret;
+
+        ret = -EINVAL;
+        pd = ctx.blkg->pd[BLKIO_POLICY_PROP];
+        if (pd && (!ctx.v || (ctx.v >= BLKIO_WEIGHT_MIN &&
+                              ctx.v <= BLKIO_WEIGHT_MAX))) {
+                pd->conf.weight = ctx.v;
+                cfq_update_blkio_group_weight(ctx.blkg, ctx.v ?: blkcg->weight);
+                ret = 0;
+        }
+
+        blkg_conf_finish(&ctx);
+        return ret;
+}
+
+static int blkcg_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val)
+{
+        struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
+        struct blkio_group *blkg;
+        struct hlist_node *n;
+
+        if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
+                return -EINVAL;
+
+        spin_lock_irq(&blkcg->lock);
+        blkcg->weight = (unsigned int)val;
+
+        hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
+                struct blkg_policy_data *pd = blkg->pd[BLKIO_POLICY_PROP];
+
+                if (pd && !pd->conf.weight)
+                        cfq_update_blkio_group_weight(blkg, blkcg->weight);
+        }
+
+        spin_unlock_irq(&blkcg->lock);
+        return 0;
+}
+
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+static u64 blkg_prfill_avg_queue_size(struct seq_file *sf,
+                                      struct blkg_policy_data *pd, int off)
+{
+        u64 samples = blkg_stat_read(&pd->stats.avg_queue_size_samples);
+        u64 v = 0;
+
+        if (samples) {
+                v = blkg_stat_read(&pd->stats.avg_queue_size_sum);
+                do_div(v, samples);
+        }
+        __blkg_prfill_u64(sf, pd, v);
+        return 0;
+}
+
+/* print avg_queue_size */
+static int blkcg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft,
+                                      struct seq_file *sf)
+{
+        struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgrp);
+
+        blkcg_print_blkgs(sf, blkcg, blkg_prfill_avg_queue_size,
+                          BLKIO_POLICY_PROP, 0, false);
+        return 0;
+}
+#endif  /* CONFIG_DEBUG_BLK_CGROUP */
+
+static struct cftype cfq_blkcg_files[] = {
+        {
+                .name = "weight_device",
+                .read_seq_string = blkcg_print_weight_device,
+                .write_string = blkcg_set_weight_device,
+                .max_write_len = 256,
+        },
+        {
+                .name = "weight",
+                .read_seq_string = blkcg_print_weight,
+                .write_u64 = blkcg_set_weight,
+        },
+        {
+                .name = "time",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats, time)),
+                .read_seq_string = blkcg_print_stat,
+        },
+        {
+                .name = "sectors",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats_cpu, sectors)),
+                .read_seq_string = blkcg_print_cpu_stat,
+        },
+        {
+                .name = "io_service_bytes",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats_cpu, service_bytes)),
+                .read_seq_string = blkcg_print_cpu_rwstat,
+        },
+        {
+                .name = "io_serviced",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats_cpu, serviced)),
+                .read_seq_string = blkcg_print_cpu_rwstat,
+        },
+        {
+                .name = "io_service_time",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats, service_time)),
+                .read_seq_string = blkcg_print_rwstat,
+        },
+        {
+                .name = "io_wait_time",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats, wait_time)),
+                .read_seq_string = blkcg_print_rwstat,
+        },
+        {
+                .name = "io_merged",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats, merged)),
+                .read_seq_string = blkcg_print_rwstat,
+        },
+        {
+                .name = "io_queued",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats, queued)),
+                .read_seq_string = blkcg_print_rwstat,
+        },
+#ifdef CONFIG_DEBUG_BLK_CGROUP
+        {
+                .name = "avg_queue_size",
+                .read_seq_string = blkcg_print_avg_queue_size,
+        },
+        {
+                .name = "group_wait_time",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats, group_wait_time)),
+                .read_seq_string = blkcg_print_stat,
+        },
+        {
+                .name = "idle_time",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats, idle_time)),
+                .read_seq_string = blkcg_print_stat,
+        },
+        {
+                .name = "empty_time",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats, empty_time)),
+                .read_seq_string = blkcg_print_stat,
+        },
+        {
+                .name = "dequeue",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats, dequeue)),
+                .read_seq_string = blkcg_print_stat,
+        },
+        {
+                .name = "unaccounted_time",
+                .private = BLKCG_STAT_PRIV(BLKIO_POLICY_PROP,
+                                offsetof(struct blkio_group_stats, unaccounted_time)),
+                .read_seq_string = blkcg_print_stat,
+        },
+#endif  /* CONFIG_DEBUG_BLK_CGROUP */
+        { }     /* terminate */
+};
 #else /* GROUP_IOSCHED */
 static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
                                                 struct blkio_cgroup *blkcg)
@@ -3715,10 +3911,10 @@ static struct elevator_type iosched_cfq = {
 static struct blkio_policy_type blkio_policy_cfq = {
         .ops = {
                 .blkio_init_group_fn =          cfq_init_blkio_group,
-                .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
         },
         .plid = BLKIO_POLICY_PROP,
         .pdata_size = sizeof(struct cfq_group),
+        .cftypes = cfq_blkcg_files,
 };
 #endif