From 8a73179956e649df0d4b3250db17734f272d8266 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 22 May 2015 18:23:20 -0400 Subject: [PATCH] writeback: reorganize [__]wb_update_bandwidth() __wb_update_bandwidth() is called from two places - fs/fs-writeback.c::balance_dirty_pages() and mm/page-writeback.c::wb_writeback(). The latter updates only the write bandwidth while the former also deals with the dirty ratelimit. The two callsites are distinguished by whether @thresh parameter is zero or not, which is cryptic. In addition, the two files define their own different versions of wb_update_bandwidth() on top of __wb_update_bandwidth(), which is confusing to say the least. This patch cleans up [__]wb_update_bandwidth() in the following ways. * __wb_update_bandwidth() now takes explicit @update_ratelimit parameter to gate dirty ratelimit handling. * mm/page-writeback.c::wb_update_bandwidth() is flattened into its caller - balance_dirty_pages(). * fs/fs-writeback.c::wb_update_bandwidth() is moved to mm/page-writeback.c and __wb_update_bandwidth() is made static. * While at it, add a lockdep assertion to __wb_update_bandwidth(). Except for the lockdep addition, this is pure reorganization and doesn't introduce any behavioral changes. Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Jan Kara Cc: Wu Fengguang Cc: Greg Thelen Signed-off-by: Jens Axboe --- fs/fs-writeback.c | 10 --------- include/linux/writeback.h | 9 +------- mm/page-writeback.c | 45 +++++++++++++++++++-------------------- 3 files changed, 23 insertions(+), 41 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index b1b3b8184500..cd89484486f6 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1087,16 +1087,6 @@ static bool over_bground_thresh(struct bdi_writeback *wb) return false; } -/* - * Called under wb->list_lock. If there are multiple wb per bdi, - * only the flusher working on the first wb should do it. - */ -static void wb_update_bandwidth(struct bdi_writeback *wb, - unsigned long start_time) -{ - __wb_update_bandwidth(wb, 0, 0, 0, 0, 0, start_time); -} - /* * Explicit flushing or periodic writeback of "old" data. * diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 0435c85d4cfa..80adf3d88d9d 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -157,14 +157,7 @@ int dirty_writeback_centisecs_handler(struct ctl_table *, int, void global_dirty_limits(unsigned long *pbackground, unsigned long *pdirty); unsigned long wb_calc_thresh(struct bdi_writeback *wb, unsigned long thresh); -void __wb_update_bandwidth(struct bdi_writeback *wb, - unsigned long thresh, - unsigned long bg_thresh, - unsigned long dirty, - unsigned long bdi_thresh, - unsigned long bdi_dirty, - unsigned long start_time); - +void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time); void page_writeback_init(void); void balance_dirty_pages_ratelimited(struct address_space *mapping); diff --git a/mm/page-writeback.c b/mm/page-writeback.c index c7745a7fe11e..bebdd41b8d8e 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1160,19 +1160,22 @@ static void wb_update_dirty_ratelimit(struct bdi_writeback *wb, trace_bdi_dirty_ratelimit(wb->bdi, dirty_rate, task_ratelimit); } -void __wb_update_bandwidth(struct bdi_writeback *wb, - unsigned long thresh, - unsigned long bg_thresh, - unsigned long dirty, - unsigned long wb_thresh, - unsigned long wb_dirty, - unsigned long start_time) +static void __wb_update_bandwidth(struct bdi_writeback *wb, + unsigned long thresh, + unsigned long bg_thresh, + unsigned long dirty, + unsigned long wb_thresh, + unsigned long wb_dirty, + unsigned long start_time, + bool update_ratelimit) { unsigned long now = jiffies; unsigned long elapsed = now - wb->bw_time_stamp; unsigned long dirtied; unsigned long written; + lockdep_assert_held(&wb->list_lock); + /* * rate-limit, only update once every 200ms. */ @@ -1189,7 +1192,7 @@ void __wb_update_bandwidth(struct bdi_writeback *wb, if (elapsed > HZ && time_before(wb->bw_time_stamp, start_time)) goto snapshot; - if (thresh) { + if (update_ratelimit) { global_update_bandwidth(thresh, dirty, now); wb_update_dirty_ratelimit(wb, thresh, bg_thresh, dirty, wb_thresh, wb_dirty, @@ -1203,20 +1206,9 @@ snapshot: wb->bw_time_stamp = now; } -static void wb_update_bandwidth(struct bdi_writeback *wb, - unsigned long thresh, - unsigned long bg_thresh, - unsigned long dirty, - unsigned long wb_thresh, - unsigned long wb_dirty, - unsigned long start_time) +void wb_update_bandwidth(struct bdi_writeback *wb, unsigned long start_time) { - if (time_is_after_eq_jiffies(wb->bw_time_stamp + BANDWIDTH_INTERVAL)) - return; - spin_lock(&wb->list_lock); - __wb_update_bandwidth(wb, thresh, bg_thresh, dirty, - wb_thresh, wb_dirty, start_time); - spin_unlock(&wb->list_lock); + __wb_update_bandwidth(wb, 0, 0, 0, 0, 0, start_time, false); } /* @@ -1467,8 +1459,15 @@ static void balance_dirty_pages(struct address_space *mapping, if (dirty_exceeded && !wb->dirty_exceeded) wb->dirty_exceeded = 1; - wb_update_bandwidth(wb, dirty_thresh, background_thresh, - nr_dirty, wb_thresh, wb_dirty, start_time); + if (time_is_before_jiffies(wb->bw_time_stamp + + BANDWIDTH_INTERVAL)) { + spin_lock(&wb->list_lock); + __wb_update_bandwidth(wb, dirty_thresh, + background_thresh, nr_dirty, + wb_thresh, wb_dirty, start_time, + true); + spin_unlock(&wb->list_lock); + } dirty_ratelimit = wb->dirty_ratelimit; pos_ratio = wb_position_ratio(wb, dirty_thresh, -- 2.20.1