This is the core io-throttle kernel infrastructure. It creates the basic
interfaces to cgroups and implements the I/O measurement and throttling
functions.

Signed-off-by: Andrea Righi
---
block/Makefile | 2 +
block/blk-io-throttle.c | 672 +++++++++++++++++++++++++++++++++++++++
include/linux/blk-io-throttle.h | 72 +++++
include/linux/cgroup_subsys.h | 6 +
init/Kconfig | 10 +
5 files changed, 762 insertions(+), 0 deletions(-)
create mode 100644 block/blk-io-throttle.c
create mode 100644 include/linux/blk-io-throttle.h

diff --git a/block/Makefile b/block/Makefile
index 208000b..b3afc86 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -13,6 +13,8 @@ obj-$(CONFIG_IOSCHED_AS) += as-iosched.o
obj-$(CONFIG_IOSCHED_DEADLINE) += deadline-iosched.o
obj-$(CONFIG_IOSCHED_CFQ) += cfq-iosched.o

+obj-$(CONFIG_CGROUP_IO_THROTTLE) += blk-io-throttle.o
+
obj-$(CONFIG_BLK_DEV_IO_TRACE) += blktrace.o
obj-$(CONFIG_BLOCK_COMPAT) += compat_ioctl.o
obj-$(CONFIG_BLK_DEV_INTEGRITY) += blk-integrity.o
diff --git a/block/blk-io-throttle.c b/block/blk-io-throttle.c
new file mode 100644
index 0000000..2510777
--- /dev/null
+++ b/block/blk-io-throttle.c
@@ -0,0 +1,672 @@
+/*
+ * blk-io-throttle.c
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * Copyright (C) 2008 Andrea Righi
+ */
+
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+#include
+
+#define IOTHROTTLE_BANDWIDTH 0
+#define IOTHROTTLE_IOPS 1
+#define IOTHROTTLE_FAILCNT 2
+
+/*
+ * Statistics for I/O bandwidth controller.
+ */
+enum iothrottle_stat_index {
+ /* # of times the cgroup has been throttled */
+ IOTHROTTLE_STAT_COUNT,
+ /* # of jiffies spent to sleep for throttling */
+ IOTHROTTLE_STAT_SLEEP,
+
+ IOTHROTTLE_STAT_NSTATS,
+};
+
+struct iothrottle_stat_cpu {
+ unsigned long long count[IOTHROTTLE_STAT_NSTATS];
+} ____cacheline_aligned_in_smp;
+
+struct iothrottle_stat {
+ struct iothrottle_stat_cpu cpustat[NR_CPUS];
+};
+
+static void __iothrottle_stat_add_safe(struct iothrottle_stat *stat,
+ enum iothrottle_stat_index idx,
+ unsigned long long val)
+{
+ const int cpu = smp_processor_id();
+
+ stat->cpustat[cpu].count[idx] += val;
+}
+
+static void iothrottle_stat_add_sleep(struct iothrottle_stat *stat,
+ unsigned long long sleep)
+{
+ unsigned long flags;
+
+ /* with irq disabled, there's no need for increment preempt count */
+ local_irq_save(flags);
+ __iothrottle_stat_add_safe(stat, IOTHROTTLE_STAT_COUNT, 1);
+ __iothrottle_stat_add_safe(stat, IOTHROTTLE_STAT_SLEEP, sleep);
+ local_irq_restore(flags);
+}
+
+static unsigned long long iothrottle_read_stat(struct iothrottle_stat *stat,
+ enum iothrottle_stat_index idx)
+{
+ int cpu;
+ unsigned long long ret = 0;
+
+ for_each_possible_cpu(cpu)
+ ret += stat->cpustat[cpu].count[idx];
+ return ret;
+}
+
+/*
+ * struct iothrottle_node - throttling rule of a single block device
+ * @node: list of per block device throttling rules
+ * @dev: block device number, used as key in the list
+ * @bw: max i/o bandwidth (in bytes/s)
+ * @iops: max i/o operations per second
+ * @stat: throttling statistics
+ *
+ * Define a i/o throttling rule for a single block device.
+ *
+ * NOTE: limiting rules always refer to dev_t; if a block device is unplugged
+ * the limiting rules defined for that device persist and they are still valid
+ * if a new device is plugged and it uses the same dev_t number.
+ */
+struct iothrottle_node {
+ struct list_head node;
+ dev_t dev;
+ struct res_counter_ratelimit bw;
+ struct res_counter_ratelimit iops;
+ struct iothrottle_stat stat;
+};
+
+/**
+ * struct iothrottle - throttling rules for a cgroup
+ * @css: pointer to the cgroup state
+ * @lock: spinlock used to protect write operations in the list
+ * @list: list of iothrottle_node elements
+ *
+ * Define multiple per-block device i/o throttling rules.
+ * Note: the list of the throttling rules is protected by RCU locking.
+ */
+struct iothrottle {
+ struct cgroup_subsys_state css;
+ spinlock_t lock; /* used to protect write operations in the list */
+ struct list_head list;
+};
+static struct iothrottle init_iothrottle;
+
+static inline struct iothrottle *cgroup_to_iothrottle(struct cgroup *cgrp)
+{
+ return container_of(cgroup_subsys_state(cgrp, iothrottle_subsys_id),
+ struct iothrottle, css);
+}
+
+/*
+ * Note: called with rcu_read_lock() held.
+ */
+static inline struct iothrottle *task_to_iothrottle(struct task_struct *task)
+{
+ return container_of(task_subsys_state(task, iothrottle_subsys_id),
+ struct iothrottle, css);
+}
+
+/*
+ * Note: called with rcu_read_lock() or iot->lock held.
+ */
+static struct iothrottle_node *
+iothrottle_search_node(const struct iothrottle *iot, dev_t dev)
+{
+ struct iothrottle_node *n;
+
+ list_for_each_entry_rcu(n, &iot->list, node)
+ if (n->dev == dev)
+ return n;
+ return NULL;
+}
+
+/*
+ * Note: called with iot->lock held.
+ */
+static inline void iothrottle_insert_node(struct iothrottle *iot,
+ struct iothrottle_node *n)
+{
+ list_add_rcu(&n->node, &iot->list);
+}
+
+/*
+ * Note: called with iot->lock held.
+ */
+static inline void
+iothrottle_replace_node(struct iothrottle *iot, struct iothrottle_node *old,
+ struct iothrottle_node *new)
+{
+ list_replace_rcu(&old->node, &new->node);
+}
+
+/*
+ * Note: called with iot->lock held.
+ */
+static inline void
+iothrottle_delete_node(struct iothrottle *iot, struct iothrottle_node *n)
+{
+ list_del_rcu(&n->node);
+}
+
+/*
+ * Note: called from kernel/cgroup.c with cgroup_lock() held.
+ */
+static struct cgroup_subsys_state *
+iothrottle_create(struct cgroup_subsys *ss, struct cgroup *cgrp)
+{
+ struct iothrottle *iot;
+
+ if (unlikely((cgrp->parent) == NULL))
+ iot = &init_iothrottle;
+ else {
+ iot = kmalloc(sizeof(*iot), GFP_KERNEL);
+ if (unlikely(!iot))
+ return ERR_PTR(-ENOMEM);
+ }
+ INIT_LIST_HEAD(&iot->list);
+ spin_lock_init(&iot->lock);
+
+ return &iot->css;
+}
+
+/*
+ * Note: called from kernel/cgroup.c with cgroup_lock() held.
+ */
+static void iothrottle_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp)
+{
+ struct iothrottle_node *n, *p;
+ struct iothrottle *iot = cgroup_to_iothrottle(cgrp);
+
+ /*
+ * don't worry about locking here, at this point there must be not any
+ * reference to the list.
+ */
+ list_for_each_entry_safe(n, p, &iot->list, node)
+ kfree(n);
+ kfree(iot);
+}
+
+/*
+ * NOTE: called with rcu_read_lock() held.
+ *
+ * do not care too much about locking for single res_counter_ratelimit values
+ * here.
+ */
+static void iothrottle_show_stats(struct seq_file *m, dev_t dev,
+ struct res_counter_ratelimit *res)
+{
+ if (!res->limit)
+ return;
+ seq_printf(m, "%u %u %llu %llu %lli %llu %llu\n",
+ MAJOR(dev), MINOR(dev),
+ res->limit, res->policy,
+ (long long)res->usage, res->max_usage,
+ res_counter_ratelimit_delta_t(res));
+}
+
+static int iothrottle_read(struct cgroup *cgrp, struct cftype *cft,
+ struct seq_file *m)
+{
+ struct iothrottle *iot = cgroup_to_iothrottle(cgrp);
+ struct iothrottle_node *n;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(n, &iot->list, node) {
+ BUG_ON(!n->dev);
+ switch (cft->private) {
+ case IOTHROTTLE_BANDWIDTH:
+ iothrottle_show_stats(m, n->dev, &n->bw);
+ break;
+ case IOTHROTTLE_IOPS:
+ iothrottle_show_stats(m, n->dev, &n->iops);
+ break;
+ case IOTHROTTLE_FAILCNT:
+ seq_printf(m, "%u %u %llu %llu\n",
+ MAJOR(n->dev), MINOR(n->dev),
+ iothrottle_read_stat(&n->stat,
+ IOTHROTTLE_STAT_COUNT),
+ iothrottle_read_stat(&n->stat,
+ IOTHROTTLE_STAT_SLEEP));
+ break;
+ }
+ }
+ rcu_read_unlock();
+ return 0;
+}
+
+static dev_t devname2dev_t(const char *buf)
+{
+ struct block_device *bdev;
+ dev_t dev = 0;
+ struct gendisk *disk;
+ int part;
+
+ /* use a lookup to validate the block device */
+ bdev = lookup_bdev(buf);
+ if (IS_ERR(bdev))
+ return 0;
+ /* only entire devices are allowed, not single partitions */
+ disk = get_gendisk(bdev->bd_dev, &part);
+ if (disk && !part) {
+ BUG_ON(!bdev->bd_inode);
+ dev = bdev->bd_inode->i_rdev;
+ }
+ bdput(bdev);
+
+ return dev;
+}
+
+/*
+ * The userspace input string must use one of the following syntaxes:
+ *
+ * dev:0 <- delete an i/o limiting rule
+ * dev:io-limit:0 <- set a leaky bucket throttling rule
+ * dev:io-limit:1:bucket-size <- set a token bucket throttling rule
+ * dev:io-limit:1 <- set a token bucket throttling rule using
+ * bucket-size == io-limit
+ */
+static int iothrottle_parse_args(char *buf, size_t nbytes, int filetype,
+ dev_t *dev, unsigned long long *iolimit,
+ unsigned long long *strategy,
+ unsigned long long *bucket_size)
+{
+ char *p;
+ int count = 0;
+ char *s[4];
+ int ret;
+
+ memset(s, 0, sizeof(s));
+ *dev = 0;
+ *iolimit = 0;
+ *strategy = 0;
+ *bucket_size = 0;
+
+ /* split the colon-delimited input string into its elements */
+ while (count < ARRAY_SIZE(s)) {
+ p = strsep(&buf, ":");
+ if (!p)
+ break;
+ if (!*p)
+ continue;
+ s[count++] = p;
+ }
+
+ /* i/o limit */
+ if (!s[1])
+ return -EINVAL;
+ ret = strict_strtoull(s[1], 10, iolimit);
+ if (ret < 0)
+ return ret;
+ if (!*iolimit)
+ goto out;
+ /* throttling strategy (leaky bucket / token bucket) */
+ if (!s[2])
+ return -EINVAL;
+ ret = strict_strtoull(s[2], 10, strategy);
+ if (ret < 0)
+ return ret;
+ switch (*strategy) {
+ case RATELIMIT_LEAKY_BUCKET:
+ goto out;
+ case RATELIMIT_TOKEN_BUCKET:
+ break;
+ default:
+ return -EINVAL;
+ }
+ /* bucket size */
+ if (!s[3])
+ *bucket_size = *iolimit;
+ else {
+ ret = strict_strtoll(s[3], 10, bucket_size);
+ if (ret < 0)
+ return ret;
+ }
+ if (*bucket_size <= 0)
+ return -EINVAL;
+out:
+ /* block device number */
+ *dev = devname2dev_t(s[0]);
+ return *dev ? 0 : -EINVAL;
+}
+
+static int iothrottle_write(struct cgroup *cgrp, struct cftype *cft,
+ const char *buffer)
+{
+ struct iothrottle *iot;
+ struct iothrottle_node *n, *newn = NULL;
+ dev_t dev;
+ unsigned long long iolimit, strategy, bucket_size;
+ char *buf;
+ size_t nbytes = strlen(buffer);
+ int ret = 0;
+
+ buf = kmalloc(nbytes + 1, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+ memcpy(buf, buffer, nbytes + 1);
+
+ ret = iothrottle_parse_args(buf, nbytes, cft->private, &dev, &iolimit,
+ &strategy, &bucket_size);
+ if (ret)
+ goto out1;
+ newn = kzalloc(sizeof(*newn), GFP_KERNEL);
+ if (!newn) {
+ ret = -ENOMEM;
+ goto out1;
+ }
+ newn->dev = dev;
+ res_counter_ratelimit_init(&newn->bw);
+ res_counter_ratelimit_init(&newn->iops);
+
+ switch (cft->private) {
+ case IOTHROTTLE_BANDWIDTH:
+ res_counter_ratelimit_set_limit(&newn->iops, 0, 0, 0);
+ res_counter_ratelimit_set_limit(&newn->bw, strategy,
+ ALIGN(iolimit, 1024), ALIGN(bucket_size, 1024));
+ break;
+ case IOTHROTTLE_IOPS:
+ res_counter_ratelimit_set_limit(&newn->bw, 0, 0, 0);
+ /*
+ * scale up iops cost by a factor of 1000, this allows to apply
+ * a more fine grained sleeps, and throttling results more
+ * precise this way.
+ */
+ res_counter_ratelimit_set_limit(&newn->iops, strategy,
+ iolimit * 1000, bucket_size * 1000);
+ break;
+ default:
+ WARN_ON(1);
+ break;
+ }
+
+ if (!cgroup_lock_live_group(cgrp)) {
+ ret = -ENODEV;
+ goto out1;
+ }
+ iot = cgroup_to_iothrottle(cgrp);
+
+ spin_lock(&iot->lock);
+ n = iothrottle_search_node(iot, dev);
+ if (!n) {
+ /* Add a new block device limiting rule */
+ iothrottle_insert_node(iot, newn);
+ newn = NULL;
+ goto out2;
+ }
+ switch (cft->private) {
+ case IOTHROTTLE_BANDWIDTH:
+ if (!iolimit && !n->iops.limit) {
+ /* Delete a block device limiting rule */
+ iothrottle_delete_node(iot, n);
+ goto out2;
+ }
+ if (!n->iops.limit)
+ break;
+ /* Update a block device limiting rule */
+ newn->iops = n->iops;
+ break;
+ case IOTHROTTLE_IOPS:
+ if (!iolimit && !n->bw.limit) {
+ /* Delete a block device limiting rule */
+ iothrottle_delete_node(iot, n);
+ goto out2;
+ }
+ if (!n->bw.limit)
+ break;
+ /* Update a block device limiting rule */
+ newn->bw = n->bw;
+ break;
+ }
+ iothrottle_replace_node(iot, n, newn);
+ newn = NULL;
+out2:
+ spin_unlock(&iot->lock);
+ cgroup_unlock();
+ if (n) {
+ synchronize_rcu();
+ kfree(n);
+ }
+out1:
+ kfree(newn);
+ kfree(buf);
+ return ret;
+}
+
+static struct cftype files[] = {
+ {
+ .name = "bandwidth-max",
+ .read_seq_string = iothrottle_read,
+ .write_string = iothrottle_write,
+ .max_write_len = 256,
+ .private = IOTHROTTLE_BANDWIDTH,
+ },
+ {
+ .name = "iops-max",
+ .read_seq_string = iothrottle_read,
+ .write_string = iothrottle_write,
+ .max_write_len = 256,
+ .private = IOTHROTTLE_IOPS,
+ },
+ {
+ .name = "throttlecnt",
+ .read_seq_string = iothrottle_read,
+ .private = IOTHROTTLE_FAILCNT,
+ },
+};
+
+static int iothrottle_populate(struct cgroup_subsys *ss, struct cgroup *cgrp)
+{
+ return cgroup_add_files(cgrp, ss, files, ARRAY_SIZE(files));
+}
+
+struct cgroup_subsys iothrottle_subsys = {
+ .name = "blockio",
+ .create = iothrottle_create,
+ .destroy = iothrottle_destroy,
+ .populate = iothrottle_populate,
+ .subsys_id = iothrottle_subsys_id,
+ .early_init = 1,
+};
+
+/*
+ * NOTE: called with rcu_read_lock() held.
+ */
+static unsigned long long iothrottle_evaluate_sleep(struct iothrottle *iot,
+ struct block_device *bdev, ssize_t bytes)
+{
+ struct iothrottle_node *n;
+ dev_t dev;
+ unsigned long long bw_sleep, iops_sleep;
+
+ /* accounting and throttling is done only on entire block devices */
+ dev = MKDEV(MAJOR(bdev->bd_inode->i_rdev), bdev->bd_disk->first_minor);
+ n = iothrottle_search_node(iot, dev);
+ if (!n)
+ return 0;
+ bw_sleep = res_counter_ratelimit_sleep(&n->bw, bytes);
+ /*
+ * scale up iops cost by a factor of 1000, this allows to apply
+ * a more fine grained sleeps, and throttling works better in
+ * this way.
+ */
+ iops_sleep = res_counter_ratelimit_sleep(&n->iops, 1000);
+ return max(bw_sleep, iops_sleep);
+}
+
+/*
+ * NOTE: called with rcu_read_lock() held.
+ */
+static void iothrottle_acct_stat(struct iothrottle *iot,
+ struct block_device *bdev, unsigned long long sleep)
+{
+ struct iothrottle_node *n;
+ dev_t dev = MKDEV(MAJOR(bdev->bd_inode->i_rdev),
+ bdev->bd_disk->first_minor);
+
+ n = iothrottle_search_node(iot, dev);
+ if (!n)
+ return;
+ iothrottle_stat_add_sleep(&n->stat, sleep);
+}
+
+int is_io_throttled(struct block_device *bdev)
+{
+ struct iothrottle *iot;
+ struct iothrottle_node *n;
+ dev_t dev;
+ int ret = 0;
+
+ if (current->flags & PF_KTHREAD)
+ return 0;
+ if (unlikely(!bdev))
+ return 0;
+ BUG_ON(!bdev->bd_inode || !bdev->bd_disk);
+
+ rcu_read_lock();
+ iot = task_to_iothrottle(current);
+ BUG_ON(!iot);
+ dev = MKDEV(MAJOR(bdev->bd_inode->i_rdev), bdev->bd_disk->first_minor);
+ n = iothrottle_search_node(iot, dev);
+ if (n)
+ ret = n->bw.limit | n->iops.limit;
+ rcu_read_unlock();
+ return ret;
+}
+
+/**
+ * cgroup_io_throttle() - account and throttle i/o activity
+ * @bdev: block device involved for the i/o.
+ * @bytes: size in bytes of the i/o operation.
+ * @can_sleep: used to set to 1 if we're in a sleep()able context, 0
+ * otherwise; into a non-sleep()able context we only account the
+ * i/o activity without applying any throttling sleep.
+ *
+ * This is the core of the block device i/o bandwidth controller. This function
+ * must be called by any function that generates i/o activity (directly or
+ * indirectly). It provides both i/o accounting and throttling functionalities;
+ * throttling is disabled if @can_sleep is set to 0.
+ *
+ * Returns the value of sleep in jiffies if it was not possible to schedule the
+ * timeout.
+ **/
+unsigned long long
+cgroup_io_throttle(struct block_device *bdev, ssize_t bytes, int can_sleep)
+{
+ struct iothrottle *iot;
+ unsigned long long sleep;
+ int count;
+
+ if (unlikely(!bdev))
+ return 0;
+ /*
+ * Never throttle kernel threads, since they may completely block other
+ * cgroups, the i/o on other block devices or even the whole system.
+ */
+ if (current->flags & PF_KTHREAD)
+ return 0;
+ /*
+ * WARNING: in_atomic() do not know about held spinlocks in
+ * non-preemptible kernels, but we want to check it here to raise
+ * potential bugs by preemptible kernels.
+ */
+ WARN_ON_ONCE(can_sleep &&
+ (irqs_disabled() || in_interrupt() || in_atomic()));
+
+ /*
+ * Do not sleep if we're inside an AIO context; just account the i/o
+ * activity. Throttling is performed in io_submit_one() returning
+ * -EAGAIN when the limits are exceeded.
+ */
+ if (is_in_aio())
+ can_sleep = 0;
+
+ rcu_read_lock();
+ iot = task_to_iothrottle(current);
+
+ BUG_ON(!iot);
+ BUG_ON(!bdev->bd_inode || !bdev->bd_disk);
+
+ sleep = iothrottle_evaluate_sleep(iot, bdev, bytes);
+ if (likely(!sleep || !can_sleep))
+ goto out;
+ /*
+ * Simple attempt to distribute throttling equally across the
+ * tasks belonging to the same cgroup (fair throttling).
+ *
+ * TODO: it would be even better to impose a sleep proportional to the
+ * amount of i/o activity done in the past (see task_io_accounting).
+ */
+ count = cgroup_task_count(iot->css.cgroup);
+ BUG_ON(!count);
+ sleep = div_u64(sleep, count);
+ if (!sleep)
+ goto out;
+
+ /* do not sleep more than hung_task_timeout_secs */
+ if (sysctl_hung_task_timeout_secs) {
+ unsigned long max_sleep =
+ msecs_to_jiffies(sysctl_hung_task_timeout_secs
+ * MSEC_PER_SEC);
+
+ if (max_sleep && (sleep > max_sleep))
+ sleep = max_sleep - 1;
+ }
+
+ iothrottle_acct_stat(iot, bdev, sleep);
+ rcu_read_unlock();
+
+ pr_debug("io-throttle: task %p (%s) must sleep %llu jiffies\n",
+ current, current->comm, sleep);
+ /*
+ * XXX: per-task statistics may be inaccurate (this is not a critical
+ * issue, anyway, respect to introduce locking overhead or increase the
+ * size of task_struct).
+ */
+ current->io_throttle_cnt++;
+ current->io_throttle_sleep += sleep;
+ schedule_timeout_killable(sleep);
+ return 0;
+out:
+ rcu_read_unlock();
+ return sleep;
+}
diff --git a/include/linux/blk-io-throttle.h b/include/linux/blk-io-throttle.h
new file mode 100644
index 0000000..f323ea1
--- /dev/null
+++ b/include/linux/blk-io-throttle.h
@@ -0,0 +1,72 @@
+#ifndef BLK_IO_THROTTLE_H
+#define BLK_IO_THROTTLE_H
+
+#include
+#include
+#include
+#include
+#include
+
+#ifdef CONFIG_CGROUP_IO_THROTTLE
+extern int is_io_throttled(struct block_device *bdev);
+
+extern unsigned long long
+cgroup_io_throttle(struct block_device *bdev, ssize_t bytes, int can_sleep);
+
+static inline void set_in_aio(void)
+{
+ atomic_set(&current->in_aio, 1);
+}
+
+static inline void unset_in_aio(void)
+{
+ atomic_set(&current->in_aio, 0);
+}
+
+static inline int is_in_aio(void)
+{
+ return atomic_read(&current->in_aio);
+}
+
+static inline unsigned long long get_io_throttle_cnt(struct task_struct *t)
+{
+ return t->io_throttle_cnt;
+}
+
+static inline unsigned long long get_io_throttle_sleep(struct task_struct *t)
+{
+ return t->io_throttle_sleep;
+}
+#else
+static inline int is_io_throttled(struct block_device *bdev)
+{
+ return 0;
+}
+
+static inline unsigned long long
+cgroup_io_throttle(struct block_device *bdev, ssize_t bytes, int can_sleep)
+{
+ return 0;
+}
+
+static inline void set_in_aio(void) { }
+
+static inline void unset_in_aio(void) { }
+
+static inline int is_in_aio(void)
+{
+ return 0;
+}
+
+static inline unsigned long long get_io_throttle_cnt(struct task_struct *t)
+{
+ return 0;
+}
+
+static inline unsigned long long get_io_throttle_sleep(struct task_struct *t)
+{
+ return 0;
+}
+#endif /* CONFIG_CGROUP_IO_THROTTLE */
+
+#endif /* BLK_IO_THROTTLE_H */
diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
index 23c02e2..198ee52 100644
--- a/include/linux/cgroup_subsys.h
+++ b/include/linux/cgroup_subsys.h
@@ -52,3 +52,9 @@ SUBSYS(memrlimit_cgroup)
#endif

/* */
+
+#ifdef CONFIG_CGROUP_IO_THROTTLE
+SUBSYS(iothrottle)
+#endif
+
+/* */
diff --git a/init/Kconfig b/init/Kconfig
index a451916..a53216c 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -306,6 +306,16 @@ config CGROUP_DEVICE
Provides a cgroup implementing whitelists for devices which
a process in the cgroup can mknod or open.

+config CGROUP_IO_THROTTLE
+ bool "Enable cgroup I/O throttling (EXPERIMENTAL)"
+ depends on CGROUPS && RESOURCE_COUNTERS && EXPERIMENTAL
+ help
+ This allows to limit the maximum I/O bandwidth for specific
+ cgroup(s).
+ See Documentation/controllers/io-throttle.txt for more information.
+
+ If unsure, say N.
+
config CPUSETS
bool "Cpuset support"
depends on SMP && CGROUPS
--
1.5.4.3

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