Convert blk-cgroup to be buildable as a module From: Ben Blum This patch modifies the Block I/O cgroup subsystem to be able to be built as a module. As the CFQ disk scheduler optionally depends on blk-cgroup, config options in block/Kconfig, block/Kconfig.iosched, and block/blk-cgroup.h are enhanced to support the new module dependency. Signed-off-by: Ben Blum --- block/Kconfig | 2 +- block/Kconfig.iosched | 2 +- block/blk-cgroup.c | 53 +++++++++++++++++++++++++++++++++++---------- block/blk-cgroup.h | 10 +++++++- include/linux/iocontext.h | 2 +- kernel/cgroup.c | 9 ++++++++ 6 files changed, 61 insertions(+), 17 deletions(-) diff --git a/block/Kconfig b/block/Kconfig index e20fbde..62a5921 100644 --- a/block/Kconfig +++ b/block/Kconfig @@ -78,7 +78,7 @@ config BLK_DEV_INTEGRITY Protection. If in doubt, say N. config BLK_CGROUP - bool + tristate depends on CGROUPS default n ---help--- diff --git a/block/Kconfig.iosched b/block/Kconfig.iosched index b71abfb..fc71cf0 100644 --- a/block/Kconfig.iosched +++ b/block/Kconfig.iosched @@ -23,6 +23,7 @@ config IOSCHED_DEADLINE config IOSCHED_CFQ tristate "CFQ I/O scheduler" + select BLK_CGROUP if CFQ_GROUP_IOSCHED default y ---help--- The CFQ I/O scheduler tries to distribute bandwidth equally @@ -35,7 +36,6 @@ config IOSCHED_CFQ config CFQ_GROUP_IOSCHED bool "CFQ Group Scheduling support" depends on IOSCHED_CFQ && CGROUPS - select BLK_CGROUP default n ---help--- Enable group IO scheduling in CFQ. diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 1fa2654..6c73380 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -23,6 +23,31 @@ 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); + bool blkiocg_css_tryget(struct blkio_cgroup *blkcg) { if (!css_tryget(&blkcg->css)) @@ -267,7 +292,8 @@ remove_entry: done: free_css_id(&blkio_subsys, &blkcg->css); rcu_read_unlock(); - kfree(blkcg); + if (blkcg != &blkio_root_cgroup) + kfree(blkcg); } static struct cgroup_subsys_state * @@ -333,17 +359,6 @@ static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup, 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); @@ -359,3 +374,17 @@ void blkio_policy_unregister(struct blkio_policy_type *blkiop) 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"); diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h index 4d316df..57648c6 100644 --- a/block/blk-cgroup.h +++ b/block/blk-cgroup.h @@ -15,7 +15,13 @@ #include -#ifdef CONFIG_BLK_CGROUP +#if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE) + +#ifndef CONFIG_BLK_CGROUP +/* When blk-cgroup is a module, its subsys_id isn't a compile-time constant */ +extern struct cgroup_subsys blkio_subsys; +#define blkio_subsys_id blkio_subsys.subsys_id +#endif struct blkio_cgroup { struct cgroup_subsys_state css; @@ -94,7 +100,7 @@ static inline void blkiocg_update_blkio_group_dequeue_stats( struct blkio_group *blkg, unsigned long dequeue) {} #endif -#ifdef CONFIG_BLK_CGROUP +#if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE) extern struct blkio_cgroup blkio_root_cgroup; extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup); extern void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg, diff --git a/include/linux/iocontext.h b/include/linux/iocontext.h index a632359..b9f109d 100644 --- a/include/linux/iocontext.h +++ b/include/linux/iocontext.h @@ -68,7 +68,7 @@ struct io_context { unsigned short ioprio; unsigned short ioprio_changed; -#ifdef CONFIG_BLK_CGROUP +#if defined(CONFIG_BLK_CGROUP) || defined(CONFIG_BLK_CGROUP_MODULE) unsigned short cgroup_changed; #endif diff --git a/kernel/cgroup.c b/kernel/cgroup.c index b4ae6ef..845a2e7 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -690,6 +690,7 @@ void cgroup_lock(void) { mutex_lock(&cgroup_mutex); } +EXPORT_SYMBOL_GPL(cgroup_lock); /** * cgroup_unlock - release lock on cgroup changes @@ -700,6 +701,7 @@ void cgroup_unlock(void) { mutex_unlock(&cgroup_mutex); } +EXPORT_SYMBOL_GPL(cgroup_unlock); /* * A couple of forward declarations required, due to cyclic reference loop: @@ -1622,6 +1624,7 @@ int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen) memmove(buf, start, buf + buflen - start); return 0; } +EXPORT_SYMBOL_GPL(cgroup_path); /** * cgroup_attach_task - attach task 'tsk' to cgroup 'cgrp' @@ -1762,6 +1765,7 @@ bool cgroup_lock_live_group(struct cgroup *cgrp) } return true; } +EXPORT_SYMBOL_GPL(cgroup_lock_live_group); static int cgroup_release_agent_write(struct cgroup *cgrp, struct cftype *cft, const char *buffer) @@ -4036,6 +4040,7 @@ void __css_put(struct cgroup_subsys_state *css) rcu_read_unlock(); WARN_ON_ONCE(val < 1); } +EXPORT_SYMBOL_GPL(__css_put); /* * Notify userspace when a cgroup is released, by running the @@ -4151,6 +4156,7 @@ unsigned short css_id(struct cgroup_subsys_state *css) return cssid->id; return 0; } +EXPORT_SYMBOL_GPL(css_id); unsigned short css_depth(struct cgroup_subsys_state *css) { @@ -4160,6 +4166,7 @@ unsigned short css_depth(struct cgroup_subsys_state *css) return cssid->depth; return 0; } +EXPORT_SYMBOL_GPL(css_depth); bool css_is_ancestor(struct cgroup_subsys_state *child, const struct cgroup_subsys_state *root) @@ -4196,6 +4203,7 @@ void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css) spin_unlock(&ss->id_lock); call_rcu(&id->rcu_head, __free_css_id_cb); } +EXPORT_SYMBOL_GPL(free_css_id); /* * This is called by init or create(). Then, calls to this function are @@ -4312,6 +4320,7 @@ struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id) return rcu_dereference(cssid->css); } +EXPORT_SYMBOL_GPL(css_lookup); /** * css_get_next - lookup next cgroup under specified hierarchy. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/