selftests/damon/_damon_sysfs: implement updat_schemes_tried_bytes command

Implement update_schemes_tried_bytes command of DAMON sysfs interface in
_damon_sysfs.py.  It is not only making the update, but also read the
updated value from the sysfs interface and store it in the Kdamond python
objects so that the user of the module can easily get the value.

Link: https://lkml.kernel.org/r/20231212194810.54457-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

tools/testing/selftests/damon/_damon_sysfs.py

@@ -76,6 +76,7 @@ class Damos:
     # todo: Support quotas, watermarks, stats, tried_regions
     idx = None
     context = None
+    tried_bytes = None
 
     def __init__(self, action='stat', access_pattern=DamosAccessPattern()):
         self.action = action
@@ -284,6 +285,19 @@ class Kdamond:
         err = write_file(os.path.join(self.sysfs_dir(), 'state'), 'on')
         return err
 
+    def update_schemes_tried_bytes(self):
+        err = write_file(os.path.join(self.sysfs_dir(), 'state'),
+                'update_schemes_tried_bytes')
+        if err != None:
+            return err
+        for context in self.contexts:
+            for scheme in context.schemes:
+                content, err = read_file(os.path.join(scheme.sysfs_dir(),
+                    'tried_regions', 'total_bytes'))
+                if err != None:
+                    return err
+                scheme.tried_bytes = int(content)
+
 class Kdamonds:
     kdamonds = []