[PATCH 07/11] blkcg: make blkg->pd an array and move configuration and stats into it

From: Tejun Heo
Date: Wed Feb 01 2012 - 16:24:01 EST

To prepare for unifying blkgs for different policies, make blkg->pd an
array with BLKIO_NR_POLICIES elements and move blkg->conf, ->stats,
and ->stats_cpu into blkg_policy_data.

This patch doesn't introduce any functional difference.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
block/blk-cgroup.c | 150 ++++++++++++++++++++++++++++++++--------------------
block/blk-cgroup.h | 18 +++---
2 files changed, 102 insertions(+), 66 deletions(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index ba49af3..5696a8d 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -184,12 +184,14 @@ static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync)
static void blkio_set_start_group_wait_time(struct blkio_group *blkg,
struct blkio_group *curr_blkg)
{
- if (blkio_blkg_waiting(&blkg->stats))
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
+
+ if (blkio_blkg_waiting(&pd->stats))
return;
if (blkg == curr_blkg)
return;
- blkg->stats.start_group_wait_time = sched_clock();
- blkio_mark_blkg_waiting(&blkg->stats);
+ pd->stats.start_group_wait_time = sched_clock();
+ blkio_mark_blkg_waiting(&pd->stats);
}

/* This should be called with the blkg->stats_lock held. */
@@ -222,24 +224,26 @@ static void blkio_end_empty_time(struct blkio_group_stats *stats)

void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
unsigned long flags;

spin_lock_irqsave(&blkg->stats_lock, flags);
- BUG_ON(blkio_blkg_idling(&blkg->stats));
- blkg->stats.start_idle_time = sched_clock();
- blkio_mark_blkg_idling(&blkg->stats);
+ BUG_ON(blkio_blkg_idling(&pd->stats));
+ pd->stats.start_idle_time = sched_clock();
+ blkio_mark_blkg_idling(&pd->stats);
spin_unlock_irqrestore(&blkg->stats_lock, flags);
}
EXPORT_SYMBOL_GPL(blkiocg_update_set_idle_time_stats);

void blkiocg_update_idle_time_stats(struct blkio_group *blkg)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
unsigned long flags;
unsigned long long now;
struct blkio_group_stats *stats;

spin_lock_irqsave(&blkg->stats_lock, flags);
- stats = &blkg->stats;
+ stats = &pd->stats;
if (blkio_blkg_idling(stats)) {
now = sched_clock();
if (time_after64(now, stats->start_idle_time))
@@ -252,11 +256,12 @@ EXPORT_SYMBOL_GPL(blkiocg_update_idle_time_stats);

void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
unsigned long flags;
struct blkio_group_stats *stats;

spin_lock_irqsave(&blkg->stats_lock, flags);
- stats = &blkg->stats;
+ stats = &pd->stats;
stats->avg_queue_size_sum +=
stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] +
stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE];
@@ -268,11 +273,12 @@ EXPORT_SYMBOL_GPL(blkiocg_update_avg_queue_size_stats);

void blkiocg_set_start_empty_time(struct blkio_group *blkg)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
unsigned long flags;
struct blkio_group_stats *stats;

spin_lock_irqsave(&blkg->stats_lock, flags);
- stats = &blkg->stats;
+ stats = &pd->stats;

if (stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] ||
stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE]) {
@@ -299,7 +305,9 @@ EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time);
void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
unsigned long dequeue)
{
- blkg->stats.dequeue += dequeue;
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
+
+ pd->stats.dequeue += dequeue;
}
EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats);
#else
@@ -312,12 +320,13 @@ void blkiocg_update_io_add_stats(struct blkio_group *blkg,
struct blkio_group *curr_blkg, bool direction,
bool sync)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
unsigned long flags;

spin_lock_irqsave(&blkg->stats_lock, flags);
- blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction,
+ blkio_add_stat(pd->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction,
sync);
- blkio_end_empty_time(&blkg->stats);
+ blkio_end_empty_time(&pd->stats);
blkio_set_start_group_wait_time(blkg, curr_blkg);
spin_unlock_irqrestore(&blkg->stats_lock, flags);
}
@@ -326,10 +335,11 @@ EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats);
void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
bool direction, bool sync)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
unsigned long flags;

spin_lock_irqsave(&blkg->stats_lock, flags);
- blkio_check_and_dec_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED],
+ blkio_check_and_dec_stat(pd->stats.stat_arr[BLKIO_STAT_QUEUED],
direction, sync);
spin_unlock_irqrestore(&blkg->stats_lock, flags);
}
@@ -338,12 +348,13 @@ EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);
void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time,
unsigned long unaccounted_time)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
unsigned long flags;

spin_lock_irqsave(&blkg->stats_lock, flags);
- blkg->stats.time += time;
+ pd->stats.time += time;
#ifdef CONFIG_DEBUG_BLK_CGROUP
- blkg->stats.unaccounted_time += unaccounted_time;
+ pd->stats.unaccounted_time += unaccounted_time;
#endif
spin_unlock_irqrestore(&blkg->stats_lock, flags);
}
@@ -356,6 +367,7 @@ EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
uint64_t bytes, bool direction, bool sync)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
struct blkio_group_stats_cpu *stats_cpu;
unsigned long flags;

@@ -366,7 +378,7 @@ void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
*/
local_irq_save(flags);

- stats_cpu = this_cpu_ptr(blkg->stats_cpu);
+ stats_cpu = this_cpu_ptr(pd->stats_cpu);

u64_stats_update_begin(&stats_cpu->syncp);
stats_cpu->sectors += bytes >> 9;
@@ -382,12 +394,13 @@ EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
void blkiocg_update_completion_stats(struct blkio_group *blkg,
uint64_t start_time, uint64_t io_start_time, bool direction, bool sync)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
struct blkio_group_stats *stats;
unsigned long flags;
unsigned long long now = sched_clock();

spin_lock_irqsave(&blkg->stats_lock, flags);
- stats = &blkg->stats;
+ stats = &pd->stats;
if (time_after64(now, io_start_time))
blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_TIME],
now - io_start_time, direction, sync);
@@ -402,6 +415,7 @@ EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);
void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
bool sync)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
struct blkio_group_stats_cpu *stats_cpu;
unsigned long flags;

@@ -412,7 +426,7 @@ void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
*/
local_irq_save(flags);

- stats_cpu = this_cpu_ptr(blkg->stats_cpu);
+ stats_cpu = this_cpu_ptr(pd->stats_cpu);

u64_stats_update_begin(&stats_cpu->syncp);
blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_MERGED], 1,
@@ -430,11 +444,17 @@ EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
*/
static void blkg_free(struct blkio_group *blkg)
{
- if (blkg) {
- free_percpu(blkg->stats_cpu);
- kfree(blkg->pd);
- kfree(blkg);
+ struct blkg_policy_data *pd;
+
+ if (!blkg)
+ return;
+
+ pd = blkg->pd[blkg->plid];
+ if (pd) {
+ free_percpu(pd->stats_cpu);
+ kfree(pd);
}
+ kfree(blkg);
}

/**
@@ -453,6 +473,7 @@ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg,
struct blkio_policy_type *pol)
{
struct blkio_group *blkg;
+ struct blkg_policy_data *pd;

/* alloc and init base part */
blkg = kzalloc_node(sizeof(*blkg), GFP_ATOMIC, q->node);
@@ -466,23 +487,26 @@ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg,
blkg->refcnt = 1;
cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));

- /* alloc per-policy data */
- blkg->pd = kzalloc_node(sizeof(*blkg->pd) + pol->pdata_size, GFP_ATOMIC,
- q->node);
- if (!blkg->pd) {
+ /* alloc per-policy data and attach it to blkg */
+ pd = kzalloc_node(sizeof(*pd) + pol->pdata_size, GFP_ATOMIC,
+ q->node);
+ if (!pd) {
blkg_free(blkg);
return NULL;
}

+ blkg->pd[pol->plid] = pd;
+ pd->blkg = blkg;
+
/* broken, read comment in the callsite */
- blkg->stats_cpu = alloc_percpu(struct blkio_group_stats_cpu);
- if (!blkg->stats_cpu) {
+
+ pd->stats_cpu = alloc_percpu(struct blkio_group_stats_cpu);
+ if (!pd->stats_cpu) {
blkg_free(blkg);
return NULL;
}

- /* attach pd to blkg and invoke per-policy init */
- blkg->pd->blkg = blkg;
+ /* invoke per-policy init */
pol->ops.blkio_init_group_fn(blkg);
return blkg;
}
@@ -659,6 +683,7 @@ EXPORT_SYMBOL_GPL(__blkg_release);

static void blkio_reset_stats_cpu(struct blkio_group *blkg)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
struct blkio_group_stats_cpu *stats_cpu;
int i, j, k;
/*
@@ -673,7 +698,7 @@ static void blkio_reset_stats_cpu(struct blkio_group *blkg)
* unless this becomes a real issue.
*/
for_each_possible_cpu(i) {
- stats_cpu = per_cpu_ptr(blkg->stats_cpu, i);
+ stats_cpu = per_cpu_ptr(pd->stats_cpu, i);
stats_cpu->sectors = 0;
for(j = 0; j < BLKIO_STAT_CPU_NR; j++)
for (k = 0; k < BLKIO_STAT_TOTAL; k++)
@@ -698,8 +723,10 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
blkcg = cgroup_to_blkio_cgroup(cgroup);
spin_lock_irq(&blkcg->lock);
hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
+
spin_lock(&blkg->stats_lock);
- stats = &blkg->stats;
+ stats = &pd->stats;
#ifdef CONFIG_DEBUG_BLK_CGROUP
idling = blkio_blkg_idling(stats);
waiting = blkio_blkg_waiting(stats);
@@ -779,13 +806,14 @@ static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t val,
static uint64_t blkio_read_stat_cpu(struct blkio_group *blkg,
enum stat_type_cpu type, enum stat_sub_type sub_type)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
int cpu;
struct blkio_group_stats_cpu *stats_cpu;
u64 val = 0, tval;

for_each_possible_cpu(cpu) {
unsigned int start;
- stats_cpu = per_cpu_ptr(blkg->stats_cpu, cpu);
+ stats_cpu = per_cpu_ptr(pd->stats_cpu, cpu);

do {
start = u64_stats_fetch_begin(&stats_cpu->syncp);
@@ -837,20 +865,21 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg,
struct cgroup_map_cb *cb, const char *dname,
enum stat_type type)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
uint64_t disk_total;
char key_str[MAX_KEY_LEN];
enum stat_sub_type sub_type;

if (type == BLKIO_STAT_TIME)
return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
- blkg->stats.time, cb, dname);
+ pd->stats.time, cb, dname);
#ifdef CONFIG_DEBUG_BLK_CGROUP
if (type == BLKIO_STAT_UNACCOUNTED_TIME)
return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
- blkg->stats.unaccounted_time, cb, dname);
+ pd->stats.unaccounted_time, cb, dname);
if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {
- uint64_t sum = blkg->stats.avg_queue_size_sum;
- uint64_t samples = blkg->stats.avg_queue_size_samples;
+ uint64_t sum = pd->stats.avg_queue_size_sum;
+ uint64_t samples = pd->stats.avg_queue_size_samples;
if (samples)
do_div(sum, samples);
else
@@ -860,26 +889,26 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg,
}
if (type == BLKIO_STAT_GROUP_WAIT_TIME)
return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
- blkg->stats.group_wait_time, cb, dname);
+ pd->stats.group_wait_time, cb, dname);
if (type == BLKIO_STAT_IDLE_TIME)
return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
- blkg->stats.idle_time, cb, dname);
+ pd->stats.idle_time, cb, dname);
if (type == BLKIO_STAT_EMPTY_TIME)
return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
- blkg->stats.empty_time, cb, dname);
+ pd->stats.empty_time, cb, dname);
if (type == BLKIO_STAT_DEQUEUE)
return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
- blkg->stats.dequeue, cb, dname);
+ pd->stats.dequeue, cb, dname);
#endif

for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
sub_type++) {
blkio_get_key_name(sub_type, dname, key_str, MAX_KEY_LEN,
false);
- cb->fill(cb, key_str, blkg->stats.stat_arr[type][sub_type]);
+ cb->fill(cb, key_str, pd->stats.stat_arr[type][sub_type]);
}
- disk_total = blkg->stats.stat_arr[type][BLKIO_STAT_READ] +
- blkg->stats.stat_arr[type][BLKIO_STAT_WRITE];
+ disk_total = pd->stats.stat_arr[type][BLKIO_STAT_READ] +
+ pd->stats.stat_arr[type][BLKIO_STAT_WRITE];
blkio_get_key_name(BLKIO_STAT_TOTAL, dname, key_str, MAX_KEY_LEN,
false);
cb->fill(cb, key_str, disk_total);
@@ -891,6 +920,7 @@ static int blkio_policy_parse_and_set(char *buf, enum blkio_policy_id plid,
{
struct gendisk *disk = NULL;
struct blkio_group *blkg = NULL;
+ struct blkg_policy_data *pd;
char *s[4], *p, *major_s = NULL, *minor_s = NULL;
unsigned long major, minor;
int i = 0, ret = -EINVAL;
@@ -950,35 +980,37 @@ static int blkio_policy_parse_and_set(char *buf, enum blkio_policy_id plid,
goto out_unlock;
}

+ pd = blkg->pd[plid];
+
switch (plid) {
case BLKIO_POLICY_PROP:
if ((temp < BLKIO_WEIGHT_MIN && temp > 0) ||
temp > BLKIO_WEIGHT_MAX)
goto out_unlock;

- blkg->conf.weight = temp;
+ pd->conf.weight = temp;
blkio_update_group_weight(blkg, temp ?: blkcg->weight);
break;
case BLKIO_POLICY_THROTL:
switch(fileid) {
case BLKIO_THROTL_read_bps_device:
- blkg->conf.bps[READ] = temp;
+ pd->conf.bps[READ] = temp;
blkio_update_group_bps(blkg, temp ?: -1, fileid);
break;
case BLKIO_THROTL_write_bps_device:
- blkg->conf.bps[WRITE] = temp;
+ pd->conf.bps[WRITE] = temp;
blkio_update_group_bps(blkg, temp ?: -1, fileid);
break;
case BLKIO_THROTL_read_iops_device:
if (temp > THROTL_IOPS_MAX)
goto out_unlock;
- blkg->conf.iops[READ] = temp;
+ pd->conf.iops[READ] = temp;
blkio_update_group_iops(blkg, temp ?: -1, fileid);
break;
case BLKIO_THROTL_write_iops_device:
if (temp > THROTL_IOPS_MAX)
goto out_unlock;
- blkg->conf.iops[WRITE] = temp;
+ pd->conf.iops[WRITE] = temp;
blkio_update_group_iops(blkg, temp ?: -1, fileid);
break;
}
@@ -1026,31 +1058,32 @@ static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft,
static void blkio_print_group_conf(struct cftype *cft, struct blkio_group *blkg,
struct seq_file *m)
{
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
const char *dname = dev_name(blkg->q->backing_dev_info.dev);
int fileid = BLKIOFILE_ATTR(cft->private);
int rw = WRITE;

switch (blkg->plid) {
case BLKIO_POLICY_PROP:
- if (blkg->conf.weight)
+ if (pd->conf.weight)
seq_printf(m, "%s\t%u\n",
- dname, blkg->conf.weight);
+ dname, pd->conf.weight);
break;
case BLKIO_POLICY_THROTL:
switch (fileid) {
case BLKIO_THROTL_read_bps_device:
rw = READ;
case BLKIO_THROTL_write_bps_device:
- if (blkg->conf.bps[rw])
+ if (pd->conf.bps[rw])
seq_printf(m, "%s\t%llu\n",
- dname, blkg->conf.bps[rw]);
+ dname, pd->conf.bps[rw]);
break;
case BLKIO_THROTL_read_iops_device:
rw = READ;
case BLKIO_THROTL_write_iops_device:
- if (blkg->conf.iops[rw])
+ if (pd->conf.iops[rw])
seq_printf(m, "%s\t%u\n",
- dname, blkg->conf.iops[rw]);
+ dname, pd->conf.iops[rw]);
break;
}
break;
@@ -1232,9 +1265,12 @@ static int blkio_weight_write(struct blkio_cgroup *blkcg, int plid, u64 val)
spin_lock_irq(&blkcg->lock);
blkcg->weight = (unsigned int)val;

- hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node)
- if (blkg->plid == plid && !blkg->conf.weight)
+ hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
+ struct blkg_policy_data *pd = blkg->pd[blkg->plid];
+
+ if (blkg->plid == plid && !pd->conf.weight)
blkio_update_group_weight(blkg, blkcg->weight);
+ }

spin_unlock_irq(&blkcg->lock);
spin_unlock(&blkio_list_lock);
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 7da1068..5dffd43 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -164,6 +164,13 @@ struct blkg_policy_data {
/* the blkg this per-policy data belongs to */
struct blkio_group *blkg;

+ /* Configuration */
+ struct blkio_group_conf conf;
+
+ struct blkio_group_stats stats;
+ /* Per cpu stats pointer */
+ struct blkio_group_stats_cpu __percpu *stats_cpu;
+
/* pol->pdata_size bytes of private data used by policy impl */
char pdata[] __aligned(__alignof__(unsigned long long));
};
@@ -180,16 +187,9 @@ struct blkio_group {
/* reference count */
int refcnt;

- /* Configuration */
- struct blkio_group_conf conf;
-
/* Need to serialize the stats in the case of reset/update */
spinlock_t stats_lock;
- struct blkio_group_stats stats;
- /* Per cpu stats pointer */
- struct blkio_group_stats_cpu __percpu *stats_cpu;
-
- struct blkg_policy_data *pd;
+ struct blkg_policy_data *pd[BLKIO_NR_POLICIES];

struct rcu_head rcu_head;
};
@@ -249,7 +249,7 @@ extern void blkg_destroy_all(struct request_queue *q);
static inline void *blkg_to_pdata(struct blkio_group *blkg,
struct blkio_policy_type *pol)
{
- return blkg ? blkg->pd->pdata : NULL;
+ return blkg ? blkg->pd[pol->plid]->pdata : NULL;
}

/**
--
1.7.7.3

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