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authorShakeel Butt <shakeelb@google.com>2021-09-02 14:53:27 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-09-03 09:58:10 -0700
commit7490a2d248145d8694e1e9828801b496250fd697 (patch)
treee05981fc7f52b23fc02ba12b8a058734baa0ba18 /fs/fs-writeback.c
parent7ae12c809f6a31d3da7b96339dbefa141884c711 (diff)
downloadlinux-7490a2d248145d8694e1e9828801b496250fd697.tar.bz2
writeback: memcg: simplify cgroup_writeback_by_id
Currently cgroup_writeback_by_id calls mem_cgroup_wb_stats() to get dirty pages for a memcg. However mem_cgroup_wb_stats() does a lot more than just get the number of dirty pages. Just directly get the number of dirty pages instead of calling mem_cgroup_wb_stats(). Also cgroup_writeback_by_id() is only called for best-effort dirty flushing, so remove the unused 'nr' parameter and no need to explicitly flush memcg stats. Link: https://lkml.kernel.org/r/20210722182627.2267368-1-shakeelb@google.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Tejun Heo <tj@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/fs-writeback.c')
-rw-r--r--fs/fs-writeback.c20
1 files changed, 9 insertions, 11 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 867984e778c3..35894a2dba75 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1039,20 +1039,20 @@ restart:
* cgroup_writeback_by_id - initiate cgroup writeback from bdi and memcg IDs
* @bdi_id: target bdi id
* @memcg_id: target memcg css id
- * @nr: number of pages to write, 0 for best-effort dirty flushing
* @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,
+int cgroup_writeback_by_id(u64 bdi_id, int memcg_id,
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;
+ unsigned long dirty;
int ret;
/* lookup bdi and memcg */
@@ -1081,24 +1081,22 @@ int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr,
}
/*
- * If @nr is zero, the caller is attempting to write out most of
+ * The caller is attempting to write out most of
* the currently dirty pages. Let's take the current dirty page
* count and inflate it by 25% which should be large enough to
* flush out most dirty pages while avoiding getting livelocked by
* concurrent dirtiers.
+ *
+ * BTW the memcg stats are flushed periodically and this is best-effort
+ * estimation, so some potential error is ok.
*/
- if (!nr) {
- unsigned long filepages, headroom, dirty, writeback;
-
- mem_cgroup_wb_stats(wb, &filepages, &headroom, &dirty,
- &writeback);
- nr = dirty * 10 / 8;
- }
+ dirty = memcg_page_state(mem_cgroup_from_css(memcg_css), NR_FILE_DIRTY);
+ dirty = dirty * 10 / 8;
/* issue the writeback work */
work = kzalloc(sizeof(*work), GFP_NOWAIT | __GFP_NOWARN);
if (work) {
- work->nr_pages = nr;
+ work->nr_pages = dirty;
work->sync_mode = WB_SYNC_NONE;
work->range_cyclic = 1;
work->reason = reason;