zonefs: Add active seq file accounting

Modify struct zonefs_sb_info to add the s_active_seq_files atomic to
count the number of seq files representing a zone that is partially
written or explicitly open, that is, to count sequential files with
a zone that is in an active state on the device.

The helper function zonefs_account_active() is introduced to update
this counter whenever a file is written or truncated. This helper is
also used in the zonefs_seq_file_write_open() and
zonefs_seq_file_write_close() functions when the explicit_open mount
option is used.

The s_active_seq_files counter is exported through sysfs using the
read-only attribute nr_active_seq_files. The device maximum number of
active zones is also exported through sysfs with the read-only attribute
max_active_seq_files.

Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/zonefs/zonefs.h b/fs/zonefs/zonefs.h
index 77d2d153c59d..4b3de66c3233 100644
--- a/fs/zonefs/zonefs.h
+++ b/fs/zonefs/zonefs.h
@@ -40,6 +40,7 @@ static inline enum zonefs_ztype zonefs_zone_type(struct blk_zone *zone)
 }
 
 #define ZONEFS_ZONE_OPEN	(1 << 0)
+#define ZONEFS_ZONE_ACTIVE	(1 << 1)
 
 /*
  * In-memory inode data.
@@ -186,6 +187,9 @@ struct zonefs_sb_info {
 	unsigned int		s_max_wro_seq_files;
 	atomic_t		s_wro_seq_files;
 
+	unsigned int		s_max_active_seq_files;
+	atomic_t		s_active_seq_files;
+
 	bool			s_sysfs_registered;
 	struct kobject		s_kobj;
 	struct completion	s_kobj_unregister;