![Gui Jianfeng](/assets/img/avatar_default.png)
There's no need to take css reference here, for the caller has already called rcu_read_lock() to prevent cgroup from being removed. Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com> Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
348 lines
8.8 KiB
C
348 lines
8.8 KiB
C
/*
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* Common Block IO controller cgroup interface
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*
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* Based on ideas and code from CFQ, CFS and BFQ:
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* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
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*
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* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
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* Paolo Valente <paolo.valente@unimore.it>
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*
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* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
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* Nauman Rafique <nauman@google.com>
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*/
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#include <linux/ioprio.h>
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#include <linux/seq_file.h>
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#include <linux/kdev_t.h>
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#include <linux/module.h>
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#include <linux/err.h>
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#include "blk-cgroup.h"
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static DEFINE_SPINLOCK(blkio_list_lock);
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static LIST_HEAD(blkio_list);
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struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
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EXPORT_SYMBOL_GPL(blkio_root_cgroup);
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struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
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{
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return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
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struct blkio_cgroup, css);
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}
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EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
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void blkiocg_update_blkio_group_stats(struct blkio_group *blkg,
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unsigned long time, unsigned long sectors)
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{
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blkg->time += time;
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blkg->sectors += sectors;
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_stats);
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void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
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struct blkio_group *blkg, void *key, dev_t dev)
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{
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unsigned long flags;
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spin_lock_irqsave(&blkcg->lock, flags);
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rcu_assign_pointer(blkg->key, key);
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blkg->blkcg_id = css_id(&blkcg->css);
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hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
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spin_unlock_irqrestore(&blkcg->lock, flags);
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#ifdef CONFIG_DEBUG_BLK_CGROUP
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/* Need to take css reference ? */
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cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
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#endif
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blkg->dev = dev;
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}
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EXPORT_SYMBOL_GPL(blkiocg_add_blkio_group);
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static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
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{
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hlist_del_init_rcu(&blkg->blkcg_node);
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blkg->blkcg_id = 0;
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}
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/*
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* returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
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* indicating that blk_group was unhashed by the time we got to it.
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*/
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int blkiocg_del_blkio_group(struct blkio_group *blkg)
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{
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struct blkio_cgroup *blkcg;
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unsigned long flags;
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struct cgroup_subsys_state *css;
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int ret = 1;
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rcu_read_lock();
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css = css_lookup(&blkio_subsys, blkg->blkcg_id);
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if (!css)
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goto out;
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blkcg = container_of(css, struct blkio_cgroup, css);
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spin_lock_irqsave(&blkcg->lock, flags);
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if (!hlist_unhashed(&blkg->blkcg_node)) {
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__blkiocg_del_blkio_group(blkg);
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ret = 0;
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}
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spin_unlock_irqrestore(&blkcg->lock, flags);
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out:
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rcu_read_unlock();
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return ret;
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}
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EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group);
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/* called under rcu_read_lock(). */
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struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
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{
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struct blkio_group *blkg;
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struct hlist_node *n;
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void *__key;
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hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
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__key = blkg->key;
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if (__key == key)
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return blkg;
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}
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return NULL;
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}
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EXPORT_SYMBOL_GPL(blkiocg_lookup_group);
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#define SHOW_FUNCTION(__VAR) \
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static u64 blkiocg_##__VAR##_read(struct cgroup *cgroup, \
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struct cftype *cftype) \
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{ \
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struct blkio_cgroup *blkcg; \
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\
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blkcg = cgroup_to_blkio_cgroup(cgroup); \
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return (u64)blkcg->__VAR; \
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}
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SHOW_FUNCTION(weight);
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#undef SHOW_FUNCTION
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static int
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blkiocg_weight_write(struct cgroup *cgroup, struct cftype *cftype, u64 val)
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{
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struct blkio_cgroup *blkcg;
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struct blkio_group *blkg;
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struct hlist_node *n;
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struct blkio_policy_type *blkiop;
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if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
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return -EINVAL;
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blkcg = cgroup_to_blkio_cgroup(cgroup);
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spin_lock(&blkio_list_lock);
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spin_lock_irq(&blkcg->lock);
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blkcg->weight = (unsigned int)val;
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hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
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list_for_each_entry(blkiop, &blkio_list, list)
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blkiop->ops.blkio_update_group_weight_fn(blkg,
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blkcg->weight);
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}
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spin_unlock_irq(&blkcg->lock);
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spin_unlock(&blkio_list_lock);
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return 0;
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}
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#define SHOW_FUNCTION_PER_GROUP(__VAR) \
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static int blkiocg_##__VAR##_read(struct cgroup *cgroup, \
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struct cftype *cftype, struct seq_file *m) \
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{ \
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struct blkio_cgroup *blkcg; \
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struct blkio_group *blkg; \
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struct hlist_node *n; \
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\
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if (!cgroup_lock_live_group(cgroup)) \
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return -ENODEV; \
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\
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blkcg = cgroup_to_blkio_cgroup(cgroup); \
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rcu_read_lock(); \
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hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {\
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if (blkg->dev) \
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seq_printf(m, "%u:%u %lu\n", MAJOR(blkg->dev), \
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MINOR(blkg->dev), blkg->__VAR); \
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} \
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rcu_read_unlock(); \
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cgroup_unlock(); \
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return 0; \
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}
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SHOW_FUNCTION_PER_GROUP(time);
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SHOW_FUNCTION_PER_GROUP(sectors);
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#ifdef CONFIG_DEBUG_BLK_CGROUP
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SHOW_FUNCTION_PER_GROUP(dequeue);
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#endif
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#undef SHOW_FUNCTION_PER_GROUP
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#ifdef CONFIG_DEBUG_BLK_CGROUP
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void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group *blkg,
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unsigned long dequeue)
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{
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blkg->dequeue += dequeue;
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}
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EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_dequeue_stats);
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#endif
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struct cftype blkio_files[] = {
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{
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.name = "weight",
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.read_u64 = blkiocg_weight_read,
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.write_u64 = blkiocg_weight_write,
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},
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{
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.name = "time",
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.read_seq_string = blkiocg_time_read,
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},
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{
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.name = "sectors",
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.read_seq_string = blkiocg_sectors_read,
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},
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#ifdef CONFIG_DEBUG_BLK_CGROUP
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{
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.name = "dequeue",
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.read_seq_string = blkiocg_dequeue_read,
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},
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#endif
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};
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static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
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{
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return cgroup_add_files(cgroup, subsys, blkio_files,
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ARRAY_SIZE(blkio_files));
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}
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static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
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{
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struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
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unsigned long flags;
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struct blkio_group *blkg;
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void *key;
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struct blkio_policy_type *blkiop;
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rcu_read_lock();
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remove_entry:
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spin_lock_irqsave(&blkcg->lock, flags);
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if (hlist_empty(&blkcg->blkg_list)) {
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spin_unlock_irqrestore(&blkcg->lock, flags);
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goto done;
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}
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blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
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blkcg_node);
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key = rcu_dereference(blkg->key);
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__blkiocg_del_blkio_group(blkg);
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spin_unlock_irqrestore(&blkcg->lock, flags);
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/*
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* This blkio_group is being unlinked as associated cgroup is going
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* away. Let all the IO controlling policies know about this event.
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*
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* Currently this is static call to one io controlling policy. Once
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* we have more policies in place, we need some dynamic registration
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* of callback function.
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*/
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spin_lock(&blkio_list_lock);
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list_for_each_entry(blkiop, &blkio_list, list)
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blkiop->ops.blkio_unlink_group_fn(key, blkg);
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spin_unlock(&blkio_list_lock);
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goto remove_entry;
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done:
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free_css_id(&blkio_subsys, &blkcg->css);
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rcu_read_unlock();
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kfree(blkcg);
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}
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static struct cgroup_subsys_state *
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blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
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{
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struct blkio_cgroup *blkcg, *parent_blkcg;
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if (!cgroup->parent) {
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blkcg = &blkio_root_cgroup;
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goto done;
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}
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/* Currently we do not support hierarchy deeper than two level (0,1) */
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parent_blkcg = cgroup_to_blkio_cgroup(cgroup->parent);
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if (css_depth(&parent_blkcg->css) > 0)
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return ERR_PTR(-EINVAL);
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blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
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if (!blkcg)
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return ERR_PTR(-ENOMEM);
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blkcg->weight = BLKIO_WEIGHT_DEFAULT;
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done:
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spin_lock_init(&blkcg->lock);
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INIT_HLIST_HEAD(&blkcg->blkg_list);
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return &blkcg->css;
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}
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/*
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* We cannot support shared io contexts, as we have no mean to support
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* two tasks with the same ioc in two different groups without major rework
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* of the main cic data structures. For now we allow a task to change
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* its cgroup only if it's the only owner of its ioc.
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*/
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static int blkiocg_can_attach(struct cgroup_subsys *subsys,
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struct cgroup *cgroup, struct task_struct *tsk,
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bool threadgroup)
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{
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struct io_context *ioc;
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int ret = 0;
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/* task_lock() is needed to avoid races with exit_io_context() */
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task_lock(tsk);
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ioc = tsk->io_context;
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if (ioc && atomic_read(&ioc->nr_tasks) > 1)
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ret = -EINVAL;
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task_unlock(tsk);
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return ret;
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}
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static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
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struct cgroup *prev, struct task_struct *tsk,
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bool threadgroup)
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{
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struct io_context *ioc;
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task_lock(tsk);
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ioc = tsk->io_context;
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if (ioc)
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ioc->cgroup_changed = 1;
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task_unlock(tsk);
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}
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struct cgroup_subsys blkio_subsys = {
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.name = "blkio",
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.create = blkiocg_create,
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.can_attach = blkiocg_can_attach,
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.attach = blkiocg_attach,
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.destroy = blkiocg_destroy,
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.populate = blkiocg_populate,
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.subsys_id = blkio_subsys_id,
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.use_id = 1,
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};
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void blkio_policy_register(struct blkio_policy_type *blkiop)
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{
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spin_lock(&blkio_list_lock);
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list_add_tail(&blkiop->list, &blkio_list);
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spin_unlock(&blkio_list_lock);
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}
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EXPORT_SYMBOL_GPL(blkio_policy_register);
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void blkio_policy_unregister(struct blkio_policy_type *blkiop)
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{
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spin_lock(&blkio_list_lock);
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list_del_init(&blkiop->list);
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spin_unlock(&blkio_list_lock);
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}
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EXPORT_SYMBOL_GPL(blkio_policy_unregister);
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