mm/damon/sysfs: implement DAMOS tried regions update command

Implement the code for filling the data of 'tried_regions' DAMON sysfs
directory.  With this commit, DAMON sysfs interface users can write a
special keyword, 'update_schemes_tried_regions' to the corresponding
'state' file of the kdamond.  Then, DAMON sysfs interface will collect the
tried regions information using the 'before_damos_apply()' callback for
one aggregation interval and populate scheme region directories with the
values.

[sj@kernel.org: skip tried regions update if the scheme directory was removed]
  Link: https://lkml.kernel.org/r/20221114182954.4745-2-sj@kernel.org
Link: https://lkml.kernel.org/r/20221101220328.95765-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/mm/damon/sysfs-common.h b/mm/damon/sysfs-common.h
index 4626b2784404..634a6e7fca78 100644
--- a/mm/damon/sysfs-common.h
+++ b/mm/damon/sysfs-common.h
@@ -44,3 +44,9 @@ int damon_sysfs_set_schemes(struct damon_ctx *ctx,
 void damon_sysfs_schemes_update_stats(
 		struct damon_sysfs_schemes *sysfs_schemes,
 		struct damon_ctx *ctx);
+
+int damon_sysfs_schemes_update_regions_start(
+		struct damon_sysfs_schemes *sysfs_schemes,
+		struct damon_ctx *ctx);
+
+int damon_sysfs_schemes_update_regions_stop(struct damon_ctx *ctx);