bcache: set writeback_rate_update_seconds in range [1, 60] seconds
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.
Changelog:
v2: fix a rebase typo in v4, which is pointed out by Michael Lyle.
v1: initial version.
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index c524305..4a6a697 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -218,7 +218,9 @@ STORE(__cached_dev)
sysfs_strtoul_clamp(writeback_rate,
dc->writeback_rate.rate, 1, INT_MAX);
- d_strtoul_nonzero(writeback_rate_update_seconds);
+ sysfs_strtoul_clamp(writeback_rate_update_seconds,
+ dc->writeback_rate_update_seconds,
+ 1, WRITEBACK_RATE_UPDATE_SECS_MAX);
d_strtoul(writeback_rate_i_term_inverse);
d_strtoul_nonzero(writeback_rate_p_term_inverse);