Implement cgroup_writeback_by_id() which initiates cgroup writeback from bdi and memcg IDs. This will be used by memcg foreign inode flushing.
Signed-off-by: Tejun Heo <[email protected]> --- fs/fs-writeback.c | 64 +++++++++++++++++++++++++++++++++++++++ include/linux/writeback.h | 4 +++ 2 files changed, 68 insertions(+) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 6129debdc938..5c79d7acefdb 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -880,6 +880,70 @@ static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, wb_put(last_wb); } +/** + * cgroup_writeback_by_id - initiate cgroup writeback from bdi and memcg IDs + * @bdi_id: target bdi id + * @memcg_id: target memcg css id + * @nr_pages: number of pages to write + * @reason: reason why some writeback work initiated + * @done: target wb_completion + * + * Initiate flush of the bdi_writeback identified by @bdi_id and @memcg_id + * with the specified parameters. + */ +int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr, + enum wb_reason reason, struct wb_completion *done) +{ + struct backing_dev_info *bdi; + struct cgroup_subsys_state *memcg_css; + struct bdi_writeback *wb; + struct wb_writeback_work *work; + int ret; + + /* lookup bdi and memcg */ + bdi = bdi_get_by_id(bdi_id); + if (!bdi) + return -ENOENT; + + rcu_read_lock(); + memcg_css = css_from_id(memcg_id, &memory_cgrp_subsys); + if (memcg_css && !css_tryget(memcg_css)) + memcg_css = NULL; + rcu_read_unlock(); + if (!memcg_css) { + ret = -ENOENT; + goto out_bdi_put; + } + + /* and find the associated wb */ + wb = wb_get_create(bdi, memcg_css, GFP_NOWAIT | __GFP_NOWARN); + if (!wb) { + ret = -ENOMEM; + goto out_css_put; + } + + /* issue the writeback work */ + work = kzalloc(sizeof(*work), GFP_NOWAIT | __GFP_NOWARN); + if (work) { + work->nr_pages = nr; + work->sync_mode = WB_SYNC_NONE; + work->reason = reason; + work->done = done; + work->auto_free = 1; + wb_queue_work(wb, work); + ret = 0; + } else { + ret = -ENOMEM; + } + + wb_put(wb); +out_css_put: + css_put(memcg_css); +out_bdi_put: + bdi_put(bdi); + return ret; +} + /** * cgroup_writeback_umount - flush inode wb switches for umount * diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 8945aac31392..ad794f2a7d42 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -217,6 +217,10 @@ void wbc_attach_and_unlock_inode(struct writeback_control *wbc, void wbc_detach_inode(struct writeback_control *wbc); void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page, size_t bytes); +int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr_pages, + enum wb_reason reason, struct wb_completion *done); +int writeback_by_id(int id, unsigned long nr, enum wb_reason reason, + struct wb_completion *done); void cgroup_writeback_umount(void); /** -- 2.17.1
