[PATCH] bcache: make writeback_cutoff and writeback_cutoff_sync writeable

[Dongdong Tao <tdd21151186@gmail.com>]

From: dongdong tao <dongdong.tao@canonical.com>

commit 9aaf51654672 ("bcache: make cutoff_writeback and
cutoff_writeback_sync tunable") intend to make these two option
configurable by user, but these two are still read-only.

Signed-off-by: dongdong tao <dongdong.tao@canonical.com>
---
 drivers/md/bcache/sysfs.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c
index 554e3afc9b68..81f4a681705c 100644
--- a/drivers/md/bcache/sysfs.c
+++ b/drivers/md/bcache/sysfs.c
@@ -102,8 +102,8 @@ read_attribute(writeback_keys_done);
 read_attribute(writeback_keys_failed);
 read_attribute(io_errors);
 read_attribute(congested);
-read_attribute(cutoff_writeback);
-read_attribute(cutoff_writeback_sync);
+rw_attribute(cutoff_writeback);
+rw_attribute(cutoff_writeback_sync);
 rw_attribute(congested_read_threshold_us);
 rw_attribute(congested_write_threshold_us);
 
@@ -902,6 +902,8 @@ STORE(__bch_cache_set)
 	sysfs_strtoul_bool(copy_gc_enabled,	c->copy_gc_enabled);
 	sysfs_strtoul_bool(idle_max_writeback_rate,
 			   c->idle_max_writeback_rate_enabled);
+	sysfs_strtoul_clamp(cutoff_writeback, bch_cutoff_writeback, 1, 100);
+	sysfs_strtoul_clamp(cutoff_writeback_sync, bch_cutoff_writeback_sync, 1, 100);
 
 	/*
 	 * write gc_after_writeback here may overwrite an already set
-- 
2.17.1