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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 /mm/page-writeback.c
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 'mm/page-writeback.c')
-rw-r--r--mm/page-writeback.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 78ef5511a198..9b95cf80b407 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2097,16 +2097,21 @@ int __set_page_dirty_no_writeback(struct page *page)
void account_page_dirtied(struct page *page, struct address_space *mapping,
struct mem_cgroup *memcg)
{
+ struct inode *inode = mapping->host;
+
trace_writeback_dirty_page(page, mapping);
if (mapping_cap_account_dirty(mapping)) {
- struct backing_dev_info *bdi = inode_to_bdi(mapping->host);
+ struct bdi_writeback *wb;
+
+ inode_attach_wb(inode, page);
+ wb = inode_to_wb(inode);
mem_cgroup_inc_page_stat(memcg, MEM_CGROUP_STAT_DIRTY);
__inc_zone_page_state(page, NR_FILE_DIRTY);
__inc_zone_page_state(page, NR_DIRTIED);
- __inc_wb_stat(&bdi->wb, WB_RECLAIMABLE);
- __inc_wb_stat(&bdi->wb, WB_DIRTIED);
+ __inc_wb_stat(wb, WB_RECLAIMABLE);
+ __inc_wb_stat(wb, WB_DIRTIED);
task_io_account_write(PAGE_CACHE_SIZE);
current->nr_dirtied++;
this_cpu_inc(bdp_ratelimits);