/* * 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 "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); bool blkiocg_css_tryget(struct blkio_cgroup *blkcg) { if (!css_tryget(&blkcg->css)) return false; return true; } EXPORT_SYMBOL_GPL(blkiocg_css_tryget); void blkiocg_css_put(struct blkio_cgroup *blkcg) { css_put(&blkcg->css); } EXPORT_SYMBOL_GPL(blkiocg_css_put); 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); void blkiocg_update_blkio_group_stats(struct blkio_group *blkg, unsigned long time, unsigned long sectors) { blkg->time += time; blkg->sectors += sectors; } EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_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_irq(&blkcg->lock); blkcg->weight = (unsigned int)val; hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) { spin_lock(&blkio_list_lock); list_for_each_entry(blkiop, &blkio_list, list) blkiop->ops.blkio_update_group_weight_fn(blkg, blkcg->weight); spin_unlock(&blkio_list_lock); } spin_unlock_irq(&blkcg->lock); return 0; } #define SHOW_FUNCTION_PER_GROUP(__VAR) \ static int blkiocg_##__VAR##_read(struct cgroup *cgroup, \ struct cftype *cftype, struct seq_file *m) \ { \ struct blkio_cgroup *blkcg; \ struct blkio_group *blkg; \ struct hlist_node *n; \ \ 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) \ seq_printf(m, "%u:%u %lu\n", MAJOR(blkg->dev), \ MINOR(blkg->dev), blkg->__VAR); \ } \ rcu_read_unlock(); \ cgroup_unlock(); \ return 0; \ } SHOW_FUNCTION_PER_GROUP(time); SHOW_FUNCTION_PER_GROUP(sectors); #ifdef CONFIG_DEBUG_BLK_CGROUP SHOW_FUNCTION_PER_GROUP(dequeue); #endif #undef SHOW_FUNCTION_PER_GROUP #ifdef CONFIG_DEBUG_BLK_CGROUP void blkiocg_update_blkio_group_dequeue_stats(struct blkio_group *blkg, unsigned long dequeue) { blkg->dequeue += dequeue; } EXPORT_SYMBOL_GPL(blkiocg_update_blkio_group_dequeue_stats); #endif struct cftype blkio_files[] = { { .name = "weight", .read_u64 = blkiocg_weight_read, .write_u64 = blkiocg_weight_write, }, { .name = "time", .read_seq_string = blkiocg_time_read, }, { .name = "sectors", .read_seq_string = blkiocg_sectors_read, }, #ifdef CONFIG_DEBUG_BLK_CGROUP { .name = "dequeue", .read_seq_string = 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(); 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); } struct cgroup_subsys blkio_subsys = { .name = "blkio", .create = blkiocg_create, .can_attach = blkiocg_can_attach, .attach = blkiocg_attach, .destroy = blkiocg_destroy, .populate = blkiocg_populate, .subsys_id = blkio_subsys_id, .use_id = 1, }; 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);