dc->writeback_rate_update_seconds can be set via sysfs and its value can be set to [1, ULONG_MAX]. It does not make sense to set such a large value, 60 seconds is long enough value considering the default 5 seconds works well for long time. Because dc->writeback_rate_update is a special delayed work, it re-arms itself inside the delayed work routine update_writeback_rate(). When stopping it by cancel_delayed_work_sync(), there should be a timeout to wait and make sure the re-armed delayed work is stopped too. A small max value of dc->writeback_rate_update_seconds is also helpful to decide a reasonable small timeout. This patch limits sysfs interface to set dc->writeback_rate_update_seconds in range of [1, 60] seconds, and replaces the hand-coded number by macros. Signed-off-by: Coly Li <colyli@xxxxxxx> --- drivers/md/bcache/sysfs.c | 3 +++ drivers/md/bcache/writeback.c | 2 +- drivers/md/bcache/writeback.h | 3 +++ 3 files changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c index b4184092c727..a74a752c9e0f 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -215,6 +215,9 @@ STORE(__cached_dev) sysfs_strtoul_clamp(writeback_rate, dc->writeback_rate.rate, 1, INT_MAX); + sysfs_strtoul_clamp(writeback_rate_update_seconds, + dc->writeback_rate_update_seconds, + 1, WRITEBACK_RATE_UPDATE_SECS_MAX); d_strtoul_nonzero(writeback_rate_update_seconds); d_strtoul(writeback_rate_i_term_inverse); d_strtoul_nonzero(writeback_rate_p_term_inverse); diff --git a/drivers/md/bcache/writeback.c b/drivers/md/bcache/writeback.c index 51306a19ab03..0ade883b6316 100644 --- a/drivers/md/bcache/writeback.c +++ b/drivers/md/bcache/writeback.c @@ -652,7 +652,7 @@ void bch_cached_dev_writeback_init(struct cached_dev *dc) dc->writeback_rate.rate = 1024; dc->writeback_rate_minimum = 8; - dc->writeback_rate_update_seconds = 5; + dc->writeback_rate_update_seconds = WRITEBACK_RATE_UPDATE_SECS_DEFAULT; dc->writeback_rate_p_term_inverse = 40; dc->writeback_rate_i_term_inverse = 10000; diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h index 66f1c527fa24..587b25599856 100644 --- a/drivers/md/bcache/writeback.h +++ b/drivers/md/bcache/writeback.h @@ -8,6 +8,9 @@ #define MAX_WRITEBACKS_IN_PASS 5 #define MAX_WRITESIZE_IN_PASS 5000 /* *512b */ +#define WRITEBACK_RATE_UPDATE_SECS_MAX 60 +#define WRITEBACK_RATE_UPDATE_SECS_DEFAULT 5 + /* * 14 (16384ths) is chosen here as something that each backing device * should be a reasonable fraction of the share, and not to blow up -- 2.15.1
