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, 14 insertions, 0 deletions

diff --git a/fs/zonefs/sysfs.c b/fs/zonefs/sysfs.c
index eaeaf983ed87..9cb6755ce39a 100644
--- a/fs/zonefs/sysfs.c
+++ b/fs/zonefs/sysfs.c
@@ -51,9 +51,23 @@ static ssize_t nr_wro_seq_files_show(struct zonefs_sb_info *sbi, char *buf)
 }
 ZONEFS_SYSFS_ATTR_RO(nr_wro_seq_files);
 
+static ssize_t max_active_seq_files_show(struct zonefs_sb_info *sbi, char *buf)
+{
+	return sysfs_emit(buf, "%u\n", sbi->s_max_active_seq_files);
+}
+ZONEFS_SYSFS_ATTR_RO(max_active_seq_files);
+
+static ssize_t nr_active_seq_files_show(struct zonefs_sb_info *sbi, char *buf)
+{
+	return sysfs_emit(buf, "%d\n", atomic_read(&sbi->s_active_seq_files));
+}
+ZONEFS_SYSFS_ATTR_RO(nr_active_seq_files);
+
 static struct attribute *zonefs_sysfs_attrs[] = {
 	ATTR_LIST(max_wro_seq_files),
 	ATTR_LIST(nr_wro_seq_files),
+	ATTR_LIST(max_active_seq_files),
+	ATTR_LIST(nr_active_seq_files),
 	NULL,
 };
 ATTRIBUTE_GROUPS(zonefs_sysfs);