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author | Tejun Heo <tj@kernel.org> | 2015-05-22 17:13:37 -0400 |
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committer | Jens Axboe <axboe@fb.com> | 2015-06-02 08:33:35 -0600 |
commit | 52ebea749aaed195245701a8f90a23d672c7a933 (patch) | |
tree | 5fac5f82f94b64a9cbcb65a99f4cddf4b13456e2 /block | |
parent | 89e9b9e07a390c50980d10aa37a04631db5a23ab (diff) | |
download | linux-exynos-52ebea749aaed195245701a8f90a23d672c7a933.tar.gz linux-exynos-52ebea749aaed195245701a8f90a23d672c7a933.tar.bz2 linux-exynos-52ebea749aaed195245701a8f90a23d672c7a933.zip |
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.c | 7 |
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; } |