From 94af584692091347baea4d810b9fc6e0f5483d42 Mon Sep 17 00:00:00 2001 From: Yafang Shao Date: Tue, 10 Oct 2017 05:44:13 +0800 Subject: [PATCH] writeback: schedule periodic writeback with sysctl After disable periodic writeback by writing 0 to dirty_writeback_centisecs, the handler wb_workfn() will not be entered again until the dirty background limit reaches or sync syscall is executed or no enough free memory available or vmscan is triggered. So the periodic writeback can't be enabled by writing a non-zero value to dirty_writeback_centisecs. As it can be disabled by sysctl, it should be able to enable by sysctl as well. Reviewed-by: Jan Kara Signed-off-by: Yafang Shao Signed-off-by: Jens Axboe --- mm/page-writeback.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 8d1fc593bce8..622a18c114ca 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1972,8 +1972,14 @@ bool wb_over_bg_thresh(struct bdi_writeback *wb) int dirty_writeback_centisecs_handler(struct ctl_table *table, int write, void __user *buffer, size_t *length, loff_t *ppos) { - proc_dointvec(table, write, buffer, length, ppos); - return 0; + unsigned int old_interval = dirty_writeback_interval; + int ret; + + ret = proc_dointvec(table, write, buffer, length, ppos); + if (!ret && !old_interval && dirty_writeback_interval) + wakeup_flusher_threads(WB_REASON_PERIODIC); + + return ret; } #ifdef CONFIG_BLOCK -- 2.30.2