blob: 9af7257f429c34dfa444f54d5e4907d7f06bd10a [file] [log] [blame]
/*
* Common Block IO controller cgroup interface
*
* Based on ideas and code from CFQ, CFS and BFQ:
* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
*
* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
* Paolo Valente <paolo.valente@unimore.it>
*
* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
* Nauman Rafique <nauman@google.com>
*/
#include <linux/ioprio.h>
#include <linux/seq_file.h>
#include <linux/kdev_t.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/blkdev.h>
#include "blk-cgroup.h"
static DEFINE_SPINLOCK(blkio_list_lock);
static LIST_HEAD(blkio_list);
struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
EXPORT_SYMBOL_GPL(blkio_root_cgroup);
static struct cgroup_subsys_state *blkiocg_create(struct cgroup_subsys *,
struct cgroup *);
static int blkiocg_can_attach(struct cgroup_subsys *, struct cgroup *,
struct task_struct *, bool);
static void blkiocg_attach(struct cgroup_subsys *, struct cgroup *,
struct cgroup *, struct task_struct *, bool);
static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *);
static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
struct cgroup_subsys blkio_subsys = {
.name = "blkio",
.create = blkiocg_create,
.can_attach = blkiocg_can_attach,
.attach = blkiocg_attach,
.destroy = blkiocg_destroy,
.populate = blkiocg_populate,
#ifdef CONFIG_BLK_CGROUP
/* note: blkio_subsys_id is otherwise defined in blk-cgroup.h */
.subsys_id = blkio_subsys_id,
#endif
.use_id = 1,
.module = THIS_MODULE,
};
EXPORT_SYMBOL_GPL(blkio_subsys);
struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
{
return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
struct blkio_cgroup, css);
}
EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
/*
* Add to the appropriate stat variable depending on the request type.
* This should be called with the blkg->stats_lock held.
*/
void io_add_stat(uint64_t *stat, uint64_t add, unsigned int flags)
{
if (flags & REQ_RW)
stat[IO_WRITE] += add;
else
stat[IO_READ] += add;
/*
* Everywhere in the block layer, an IO is treated as sync if it is a
* read or a SYNC write. We follow the same norm.
*/
if (!(flags & REQ_RW) || flags & REQ_RW_SYNC)
stat[IO_SYNC] += add;
else
stat[IO_ASYNC] += add;
}
void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time)
{
unsigned long flags;
spin_lock_irqsave(&blkg->stats_lock, flags);
blkg->stats.time += time;
spin_unlock_irqrestore(&blkg->stats_lock, flags);
}
EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
void blkiocg_update_request_dispatch_stats(struct blkio_group *blkg,
struct request *rq)
{
struct blkio_group_stats *stats;
unsigned long flags;
spin_lock_irqsave(&blkg->stats_lock, flags);
stats = &blkg->stats;
stats->sectors += blk_rq_sectors(rq);
io_add_stat(stats->io_serviced, 1, rq->cmd_flags);
io_add_stat(stats->io_service_bytes, blk_rq_sectors(rq) << 9,
rq->cmd_flags);
spin_unlock_irqrestore(&blkg->stats_lock, flags);
}
void blkiocg_update_request_completion_stats(struct blkio_group *blkg,
struct request *rq)
{
struct blkio_group_stats *stats;
unsigned long flags;
unsigned long long now = sched_clock();
spin_lock_irqsave(&blkg->stats_lock, flags);
stats = &blkg->stats;
if (time_after64(now, rq->io_start_time_ns))
io_add_stat(stats->io_service_time, now - rq->io_start_time_ns,
rq->cmd_flags);
if (time_after64(rq->io_start_time_ns, rq->start_time_ns))
io_add_stat(stats->io_wait_time,
rq->io_start_time_ns - rq->start_time_ns,
rq->cmd_flags);
spin_unlock_irqrestore(&blkg->stats_lock, flags);
}
EXPORT_SYMBOL_GPL(blkiocg_update_request_completion_stats);
void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
struct blkio_group *blkg, void *key, dev_t dev)
{
unsigned long flags;
spin_lock_irqsave(&blkcg->lock, flags);
rcu_assign_pointer(blkg->key, key);
blkg->blkcg_id = css_id(&blkcg->css);
hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
spin_unlock_irqrestore(&blkcg->lock, flags);
#ifdef CONFIG_DEBUG_BLK_CGROUP
/* Need to take css reference ? */
cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
#endif
blkg->dev = dev;
}
EXPORT_SYMBOL_GPL(blkiocg_add_blkio_group);
static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
{
hlist_del_init_rcu(&blkg->blkcg_node);
blkg->blkcg_id = 0;
}
/*
* returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
* indicating that blk_group was unhashed by the time we got to it.
*/
int blkiocg_del_blkio_group(struct blkio_group *blkg)
{
struct blkio_cgroup *blkcg;
unsigned long flags;
struct cgroup_subsys_state *css;
int ret = 1;
rcu_read_lock();
css = css_lookup(&blkio_subsys, blkg->blkcg_id);
if (!css)
goto out;
blkcg = container_of(css, struct blkio_cgroup, css);
spin_lock_irqsave(&blkcg->lock, flags);
if (!hlist_unhashed(&blkg->blkcg_node)) {
__blkiocg_del_blkio_group(blkg);
ret = 0;
}
spin_unlock_irqrestore(&blkcg->lock, flags);
out:
rcu_read_unlock();
return ret;
}
EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group);
/* called under rcu_read_lock(). */
struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
{
struct blkio_group *blkg;
struct hlist_node *n;
void *__key;
hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
__key = blkg->key;
if (__key == key)
return blkg;
}
return NULL;
}
EXPORT_SYMBOL_GPL(blkiocg_lookup_group);
#define SHOW_FUNCTION(__VAR) \
static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup, \
struct cftype *cftype) \
{ \
struct blkio_cgroup *blkcg; \
\
blkcg = cgroup_to_blkio_cgroup(cgroup); \
return (u64)blkcg->__VAR; \
}
SHOW_FUNCTION(weight);
#undef SHOW_FUNCTION
static int
blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
{
struct blkio_cgroup *blkcg;
struct blkio_group *blkg;
struct hlist_node *n;
struct blkio_policy_type *blkiop;
if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
return -EINVAL;
blkcg = cgroup_to_blkio_cgroup(cgroup);
spin_lock(&blkio_list_lock);
spin_lock_irq(&blkcg->lock);
blkcg->weight = (unsigned int)val;
hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
list_for_each_entry(blkiop, &blkio_list, list)
blkiop->ops.blkio_update_group_weight_fn(blkg,
blkcg->weight);
}
spin_unlock_irq(&blkcg->lock);
spin_unlock(&blkio_list_lock);
return 0;
}
static int
blkiocg_reset_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
{
struct blkio_cgroup *blkcg;
struct blkio_group *blkg;
struct hlist_node *n;
struct blkio_group_stats *stats;
blkcg = cgroup_to_blkio_cgroup(cgroup);
spin_lock_irq(&blkcg->lock);
hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
spin_lock(&blkg->stats_lock);
stats = &blkg->stats;
memset(stats, 0, sizeof(struct blkio_group_stats));
spin_unlock(&blkg->stats_lock);
}
spin_unlock_irq(&blkcg->lock);
return 0;
}
void get_key_name(int type, char *disk_id, char *str, int chars_left)
{
strlcpy(str, disk_id, chars_left);
chars_left -= strlen(str);
if (chars_left <= 0) {
printk(KERN_WARNING
"Possibly incorrect cgroup stat display format");
return;
}
switch (type) {
case IO_READ:
strlcat(str, " Read", chars_left);
break;
case IO_WRITE:
strlcat(str, " Write", chars_left);
break;
case IO_SYNC:
strlcat(str, " Sync", chars_left);
break;
case IO_ASYNC:
strlcat(str, " Async", chars_left);
break;
case IO_TYPE_MAX:
strlcat(str, " Total", chars_left);
break;
default:
strlcat(str, " Invalid", chars_left);
}
}
typedef uint64_t (get_var) (struct blkio_group *, int);
#define MAX_KEY_LEN 100
uint64_t get_typed_stat(struct blkio_group *blkg, struct cgroup_map_cb *cb,
get_var *getvar, char *disk_id)
{
uint64_t disk_total;
char key_str[MAX_KEY_LEN];
int type;
for (type = 0; type < IO_TYPE_MAX; type++) {
get_key_name(type, disk_id, key_str, MAX_KEY_LEN);
cb->fill(cb, key_str, getvar(blkg, type));
}
disk_total = getvar(blkg, IO_READ) + getvar(blkg, IO_WRITE);
get_key_name(IO_TYPE_MAX, disk_id, key_str, MAX_KEY_LEN);
cb->fill(cb, key_str, disk_total);
return disk_total;
}
uint64_t get_stat(struct blkio_group *blkg, struct cgroup_map_cb *cb,
get_var *getvar, char *disk_id)
{
uint64_t var = getvar(blkg, 0);
cb->fill(cb, disk_id, var);
return var;
}
#define GET_STAT_INDEXED(__VAR) \
uint64_t get_##__VAR##_stat(struct blkio_group *blkg, int type) \
{ \
return blkg->stats.__VAR[type]; \
} \
GET_STAT_INDEXED(io_service_bytes);
GET_STAT_INDEXED(io_serviced);
GET_STAT_INDEXED(io_service_time);
GET_STAT_INDEXED(io_wait_time);
#undef GET_STAT_INDEXED
#define GET_STAT(__VAR, __CONV) \
uint64_t get_##__VAR##_stat(struct blkio_group *blkg, int dummy) \
{ \
uint64_t data = blkg->stats.__VAR; \
if (__CONV) \
data = (uint64_t)jiffies_to_msecs(data) * NSEC_PER_MSEC;\
return data; \
}
GET_STAT(time, 1);
GET_STAT(sectors, 0);
#ifdef CONFIG_DEBUG_BLK_CGROUP
GET_STAT(dequeue, 0);
#endif
#undef GET_STAT
#define SHOW_FUNCTION_PER_GROUP(__VAR, get_stats, getvar, show_total) \
static int blkiocg_##__VAR##_read(struct cgroup *cgroup, \
struct cftype *cftype, struct cgroup_map_cb *cb) \
{ \
struct blkio_cgroup *blkcg; \
struct blkio_group *blkg; \
struct hlist_node *n; \
uint64_t cgroup_total = 0; \
char disk_id[10]; \
\
if (!cgroup_lock_live_group(cgroup)) \
return -ENODEV; \
\
blkcg = cgroup_to_blkio_cgroup(cgroup); \
rcu_read_lock(); \
hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {\
if (blkg->dev) { \
spin_lock_irq(&blkg->stats_lock); \
snprintf(disk_id, 10, "%u:%u", MAJOR(blkg->dev),\
MINOR(blkg->dev)); \
cgroup_total += get_stats(blkg, cb, getvar, \
disk_id); \
spin_unlock_irq(&blkg->stats_lock); \
} \
} \
if (show_total) \
cb->fill(cb, "Total", cgroup_total); \
rcu_read_unlock(); \
cgroup_unlock(); \
return 0; \
}
SHOW_FUNCTION_PER_GROUP(time, get_stat, get_time_stat, 0);
SHOW_FUNCTION_PER_GROUP(sectors, get_stat, get_sectors_stat, 0);
SHOW_FUNCTION_PER_GROUP(io_service_bytes, get_typed_stat,
get_io_service_bytes_stat, 1);
SHOW_FUNCTION_PER_GROUP(io_serviced, get_typed_stat, get_io_serviced_stat, 1);
SHOW_FUNCTION_PER_GROUP(io_service_time, get_typed_stat,
get_io_service_time_stat, 1);
SHOW_FUNCTION_PER_GROUP(io_wait_time, get_typed_stat, get_io_wait_time_stat, 1);
#ifdef CONFIG_DEBUG_BLK_CGROUP
SHOW_FUNCTION_PER_GROUP(dequeue, get_stat, get_dequeue_stat, 0);
#endif
#undef SHOW_FUNCTION_PER_GROUP
#ifdef CONFIG_DEBUG_BLK_CGROUP
void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
unsigned long dequeue)
{
blkg->stats.dequeue += dequeue;
}
EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats);
#endif
struct cftype blkio_files[] = {
{
.name = "weight",
.read_u64 = blkiocg_weight_read,
.write_u64 = blkiocg_weight_write,
},
{
.name = "time",
.read_map = blkiocg_time_read,
.write_u64 = blkiocg_reset_write,
},
{
.name = "sectors",
.read_map = blkiocg_sectors_read,
.write_u64 = blkiocg_reset_write,
},
{
.name = "io_service_bytes",
.read_map = blkiocg_io_service_bytes_read,
.write_u64 = blkiocg_reset_write,
},
{
.name = "io_serviced",
.read_map = blkiocg_io_serviced_read,
.write_u64 = blkiocg_reset_write,
},
{
.name = "io_service_time",
.read_map = blkiocg_io_service_time_read,
.write_u64 = blkiocg_reset_write,
},
{
.name = "io_wait_time",
.read_map = blkiocg_io_wait_time_read,
.write_u64 = blkiocg_reset_write,
},
#ifdef CONFIG_DEBUG_BLK_CGROUP
{
.name = "dequeue",
.read_map = blkiocg_dequeue_read,
},
#endif
};
static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
{
return cgroup_add_files(cgroup, subsys, blkio_files,
ARRAY_SIZE(blkio_files));
}
static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
unsigned long flags;
struct blkio_group *blkg;
void *key;
struct blkio_policy_type *blkiop;
rcu_read_lock();
remove_entry:
spin_lock_irqsave(&blkcg->lock, flags);
if (hlist_empty(&blkcg->blkg_list)) {
spin_unlock_irqrestore(&blkcg->lock, flags);
goto done;
}
blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
blkcg_node);
key = rcu_dereference(blkg->key);
__blkiocg_del_blkio_group(blkg);
spin_unlock_irqrestore(&blkcg->lock, flags);
/*
* This blkio_group is being unlinked as associated cgroup is going
* away. Let all the IO controlling policies know about this event.
*
* Currently this is static call to one io controlling policy. Once
* we have more policies in place, we need some dynamic registration
* of callback function.
*/
spin_lock(&blkio_list_lock);
list_for_each_entry(blkiop, &blkio_list, list)
blkiop->ops.blkio_unlink_group_fn(key, blkg);
spin_unlock(&blkio_list_lock);
goto remove_entry;
done:
free_css_id(&blkio_subsys, &blkcg->css);
rcu_read_unlock();
if (blkcg != &blkio_root_cgroup)
kfree(blkcg);
}
static struct cgroup_subsys_state *
blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
{
struct blkio_cgroup *blkcg, *parent_blkcg;
if (!cgroup->parent) {
blkcg = &blkio_root_cgroup;
goto done;
}
/* Currently we do not support hierarchy deeper than two level (0,1) */
parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent);
if (css_depth(&parent_blkcg->css) > 0)
return ERR_PTR(-EINVAL);
blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
if (!blkcg)
return ERR_PTR(-ENOMEM);
blkcg->weight = BLKIO_WEIGHT_DEFAULT;
done:
spin_lock_init(&blkcg->lock);
INIT_HLIST_HEAD(&blkcg->blkg_list);
return &blkcg->css;
}
/*
* We cannot support shared io contexts, as we have no mean to support
* two tasks with the same ioc in two different groups without major rework
* of the main cic data structures. For now we allow a task to change
* its cgroup only if it's the only owner of its ioc.
*/
static int blkiocg_can_attach(struct cgroup_subsys *subsys,
struct cgroup *cgroup, struct task_struct *tsk,
bool threadgroup)
{
struct io_context *ioc;
int ret = 0;
/* task_lock() is needed to avoid races with exit_io_context() */
task_lock(tsk);
ioc = tsk->io_context;
if (ioc && atomic_read(&ioc->nr_tasks) > 1)
ret = -EINVAL;
task_unlock(tsk);
return ret;
}
static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
struct cgroup *prev, struct task_struct *tsk,
bool threadgroup)
{
struct io_context *ioc;
task_lock(tsk);
ioc = tsk->io_context;
if (ioc)
ioc->cgroup_changed = 1;
task_unlock(tsk);
}
void blkio_policy_register(struct blkio_policy_type *blkiop)
{
spin_lock(&blkio_list_lock);
list_add_tail(&blkiop->list, &blkio_list);
spin_unlock(&blkio_list_lock);
}
EXPORT_SYMBOL_GPL(blkio_policy_register);
void blkio_policy_unregister(struct blkio_policy_type *blkiop)
{
spin_lock(&blkio_list_lock);
list_del_init(&blkiop->list);
spin_unlock(&blkio_list_lock);
}
EXPORT_SYMBOL_GPL(blkio_policy_unregister);
static int __init init_cgroup_blkio(void)
{
return cgroup_load_subsys(&blkio_subsys);
}
static void __exit exit_cgroup_blkio(void)
{
cgroup_unload_subsys(&blkio_subsys);
}
module_init(init_cgroup_blkio);
module_exit(exit_cgroup_blkio);
MODULE_LICENSE("GPL");