Commit cf4973d8 authored by chenridong's avatar chenridong Committed by yanhaitao
Browse files

cgroup: support cgroup writeback on cgroupv1 

hulk inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8LY4S



-------------------------------

In cgroupv1, cgroup writeback is not supproted for two problems:
1) Blkcg_css and memcg_css are mounted on different cgroup trees.
   Therefore, blkcg_css cannot be found according to a certain memcg_css.
2) Buffer I/O is worked by kthread, which is in the root_blkcg.
   Therefore, blkcg cannot limit wbps and wiops of buffer I/O.

We solve the two problems to support cgroup writeback on cgroupv1.
1) A memcg is attached to the blkcg_root css when the memcg was created.
2) We add a member "wb_blkio_ino" in mem_cgroup_legacy_files.
   User can attach a memcg to a cerntain blkcg through echo the file
   inode of the blkcg into the wb_blkio of the memcg.
3) inode_cgwb_enabled() return true when memcg and io are both mounted
   on cgroupv2 or both on cgroupv1.
4) Buffer I/O can find a blkcg according to its memcg.

Thus, a memcg can find a certain blkcg, and cgroup writeback can be
supported on cgroupv1.

Signed-off-by: default avatarLu Jialin <lujialin4@huawei.com>
Signed-off-by: default avatarchenridong <chenridong@huawei.com>
parent b4f5f93b

block/blk-cgroup.c

+3 −0
Original line number Diff line number Diff line
@@ -1363,6 +1363,9 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css) 
	INIT_HLIST_HEAD(&blkcg->blkg_list);

#ifdef CONFIG_CGROUP_WRITEBACK

	INIT_LIST_HEAD(&blkcg->cgwb_list);

#endif

#ifdef CONFIG_CGROUP_V1_WRITEBACK

	INIT_LIST_HEAD(&blkcg->memcg_list);

#endif

	list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs);

block/blk-cgroup.h

+3 −0
Original line number Diff line number Diff line
@@ -114,6 +114,9 @@ struct blkcg { 
#ifdef CONFIG_CGROUP_WRITEBACK

	struct list_head		cgwb_list;

#endif

#ifdef CONFIG_CGROUP_V1_WRITEBACK

	struct list_head		memcg_list;

#endif

};



static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)

include/linux/backing-dev.h

+25 −4
Original line number Diff line number Diff line
@@ -149,6 +149,26 @@ static inline bool mapping_can_writeback(struct address_space *mapping) 
	return inode_to_bdi(mapping->host)->capabilities & BDI_CAP_WRITEBACK;

}



#ifdef CONFIG_CGROUP_V1_WRITEBACK

void wb_kill_memcg_blkcg(struct cgroup_subsys_state *css);

void wb_attach_memcg_to_blkcg(struct cgroup_subsys_state *memcg_css,

			      struct cgroup_subsys_state *blkcg_css);

bool cgroup1_writeback_enabled(void);

#else

static inline void wb_kill_memcg_blkcg(struct cgroup_subsys_state *css)

{

}

static inline void

wb_attach_memcg_to_blkcg(struct cgroup_subsys_state *memcg_css,

			 struct cgroup_subsys_state *blkcg_css)

{

}

static inline bool cgroup1_writeback_enabled(void)

{

	return false;

}

#endif /* CONFIG_CGROUP_V1_WRITEBACK */



#ifdef CONFIG_CGROUP_WRITEBACK



struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
@@ -174,8 +194,9 @@ static inline bool inode_cgwb_enabled(struct inode *inode) 
{

	struct backing_dev_info *bdi = inode_to_bdi(inode);



	return cgroup_subsys_on_dfl(memory_cgrp_subsys) &&

		cgroup_subsys_on_dfl(io_cgrp_subsys) &&

	return ((cgroup_subsys_on_dfl(memory_cgrp_subsys) &&

	       cgroup_subsys_on_dfl(io_cgrp_subsys)) ||

	       cgroup1_writeback_enabled()) &&

	       (bdi->capabilities & BDI_CAP_WRITEBACK) &&

	       (inode->i_sb->s_iflags & SB_I_CGROUPWB);

}

include/linux/memcontrol.h

+5 −0
Original line number Diff line number Diff line
@@ -320,6 +320,11 @@ struct mem_cgroup { 
	struct memcg_cgwb_frn cgwb_frn[MEMCG_CGWB_FRN_CNT];

#endif



#ifdef CONFIG_CGROUP_V1_WRITEBACK

	struct cgroup_subsys_state	*wb_blk_css;

	struct list_head		memcg_node;

#endif



	/* List of events which userspace want to receive */

	struct list_head event_list;

	spinlock_t event_list_lock;

init/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -981,6 +981,11 @@ config CGROUP_WRITEBACK 
	depends on MEMCG && BLK_CGROUP

	default y



config CGROUP_V1_WRITEBACK

	bool "Support Cgroup Writeback On Cgroupv1"

	depends on CGROUP_WRITEBACK

	default n



menuconfig CGROUP_SCHED

	bool "CPU controller"

	default n