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authorTejun Heo <tj@kernel.org>2015-05-22 17:13:37 -0400
committerJens Axboe <axboe@fb.com>2015-06-02 08:33:35 -0600
commit52ebea749aaed195245701a8f90a23d672c7a933 (patch)
tree5fac5f82f94b64a9cbcb65a99f4cddf4b13456e2 /block
parent89e9b9e07a390c50980d10aa37a04631db5a23ab (diff)
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 'block')
-rw-r--r--block/blk-cgroup.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 54ec1721cd3e..979cfdbb94e0 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -15,6 +15,7 @@
#include <linux/module.h>
#include <linux/err.h>
#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
#include <linux/slab.h>
#include <linux/genhd.h>
#include <linux/delay.h>
@@ -797,6 +798,8 @@ static void blkcg_css_offline(struct cgroup_subsys_state *css)
}
spin_unlock_irq(&blkcg->lock);
+
+ wb_blkcg_offline(blkcg);
}
static void blkcg_css_free(struct cgroup_subsys_state *css)
@@ -827,7 +830,9 @@ done:
spin_lock_init(&blkcg->lock);
INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_ATOMIC);
INIT_HLIST_HEAD(&blkcg->blkg_list);
-
+#ifdef CONFIG_CGROUP_WRITEBACK
+ INIT_LIST_HEAD(&blkcg->cgwb_list);
+#endif
return &blkcg->css;
}