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authorTejun Heo <tj@kernel.org>2015-05-23 00:13:37 +0300
committerJens Axboe <axboe@fb.com>2015-06-02 17:33:35 +0300
commit52ebea749aaed195245701a8f90a23d672c7a933 (patch)
tree5fac5f82f94b64a9cbcb65a99f4cddf4b13456e2 /mm/memcontrol.c
parent89e9b9e07a390c50980d10aa37a04631db5a23ab (diff)
downloadlinux-52ebea749aaed195245701a8f90a23d672c7a933.tar.xz
writeback: make backing_dev_info host cgroup-specific bdi_writebacks
For the planned cgroup writeback support, on each bdi (backing_dev_info), each memcg will be served by a separate wb (bdi_writeback). This patch updates bdi so that a bdi can host multiple wbs (bdi_writebacks). On the default hierarchy, blkcg implicitly enables memcg. This allows using memcg's page ownership for attributing writeback IOs, and every memcg - blkcg combination can be served by its own wb by assigning a dedicated wb to each memcg. This means that there may be multiple wb's of a bdi mapped to the same blkcg. As congested state is per blkcg - bdi combination, those wb's should share the same congested state. This is achieved by tracking congested state via bdi_writeback_congested structs which are keyed by blkcg. bdi->wb remains unchanged and will keep serving the root cgroup. cgwb's (cgroup wb's) for non-root cgroups are created on-demand or looked up while dirtying an inode according to the memcg of the page being dirtied or current task. Each cgwb is indexed on bdi->cgwb_tree by its memcg id. Once an inode is associated with its wb, it can be retrieved using inode_to_wb(). Currently, none of the filesystems has FS_CGROUP_WRITEBACK and all pages will keep being associated with bdi->wb. v3: inode_attach_wb() in account_page_dirtied() moved inside mapping_cap_account_dirty() block where it's known to be !NULL. Also, an unnecessary NULL check before kfree() removed. Both detected by the kbuild bot. v2: Updated so that wb association is per inode and wb is per memcg rather than blkcg. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: kbuild test robot <fengguang.wu@intel.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'mm/memcontrol.c')
-rw-r--r--mm/memcontrol.c19
1 files changed, 18 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5c270a03729c..49e5aa6abca6 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -348,6 +348,10 @@ struct mem_cgroup {
atomic_t numainfo_updating;
#endif
+#ifdef CONFIG_CGROUP_WRITEBACK
+ struct list_head cgwb_list;
+#endif
+
/* List of events which userspace want to receive */
struct list_head event_list;
spinlock_t event_list_lock;
@@ -4030,6 +4034,15 @@ static void memcg_destroy_kmem(struct mem_cgroup *memcg)
}
#endif
+#ifdef CONFIG_CGROUP_WRITEBACK
+
+struct list_head *mem_cgroup_cgwb_list(struct mem_cgroup *memcg)
+{
+ return &memcg->cgwb_list;
+}
+
+#endif /* CONFIG_CGROUP_WRITEBACK */
+
/*
* DO NOT USE IN NEW FILES.
*
@@ -4494,7 +4507,9 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
#ifdef CONFIG_MEMCG_KMEM
memcg->kmemcg_id = -1;
#endif
-
+#ifdef CONFIG_CGROUP_WRITEBACK
+ INIT_LIST_HEAD(&memcg->cgwb_list);
+#endif
return &memcg->css;
free_out:
@@ -4582,6 +4597,8 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
vmpressure_cleanup(&memcg->vmpressure);
memcg_deactivate_kmem(memcg);
+
+ wb_memcg_offline(memcg);
}
static void mem_cgroup_css_free(struct cgroup_subsys_state *css)