f2fs: show more discard status by sysfs

The current pending_discard attr just only shows the discard_cmd_cnt
information. More discard status can be shown so that we can check
them through sysfs when needed.

Signed-off-by: Zhiguo Niu <zhiguo.niu@unisoc.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Author: Zhiguo Niu

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -498,6 +498,21 @@ Description:	Show status of f2fs checkpoint in real time.
 		CP_RESIZEFS_FLAG		0x00004000
 		=============================== ==============================
 
+What:		/sys/fs/f2fs/<disk>/stat/issued_discard
+Date:		December 2023
+Contact:	"Zhiguo Niu" <zhiguo.niu@unisoc.com>
+Description:	Shows the number of issued discard.
+
+What:		/sys/fs/f2fs/<disk>/stat/queued_discard
+Date:		December 2023
+Contact:	"Zhiguo Niu" <zhiguo.niu@unisoc.com>
+Description:	Shows the number of queued discard.
+
+What:		/sys/fs/f2fs/<disk>/stat/undiscard_blks
+Date:		December 2023
+Contact:	"Zhiguo Niu" <zhiguo.niu@unisoc.com>
+Description:	Shows the total number of undiscard blocks.
+
 What:		/sys/fs/f2fs/<disk>/ckpt_thread_ioprio
 Date:		January 2021
 Contact:	"Daeho Jeong" <daehojeong@google.com>

fs/f2fs/sysfs.c

@@ -143,6 +143,33 @@ static ssize_t pending_discard_show(struct f2fs_attr *a,
 				&SM_I(sbi)->dcc_info->discard_cmd_cnt));
 }
 
+static ssize_t issued_discard_show(struct f2fs_attr *a,
+		struct f2fs_sb_info *sbi, char *buf)
+{
+	if (!SM_I(sbi)->dcc_info)
+		return -EINVAL;
+	return sysfs_emit(buf, "%llu\n", (unsigned long long)atomic_read(
+				&SM_I(sbi)->dcc_info->issued_discard));
+}
+
+static ssize_t queued_discard_show(struct f2fs_attr *a,
+		struct f2fs_sb_info *sbi, char *buf)
+{
+	if (!SM_I(sbi)->dcc_info)
+		return -EINVAL;
+	return sysfs_emit(buf, "%llu\n", (unsigned long long)atomic_read(
+				&SM_I(sbi)->dcc_info->queued_discard));
+}
+
+static ssize_t undiscard_blks_show(struct f2fs_attr *a,
+		struct f2fs_sb_info *sbi, char *buf)
+{
+	if (!SM_I(sbi)->dcc_info)
+		return -EINVAL;
+	return sysfs_emit(buf, "%u\n",
+				SM_I(sbi)->dcc_info->undiscard_blks);
+}
+
 static ssize_t gc_mode_show(struct f2fs_attr *a,
 		struct f2fs_sb_info *sbi, char *buf)
 {
@@ -1213,9 +1240,16 @@ ATTRIBUTE_GROUPS(f2fs_feat);
 
 F2FS_GENERAL_RO_ATTR(sb_status);
 F2FS_GENERAL_RO_ATTR(cp_status);
+F2FS_GENERAL_RO_ATTR(issued_discard);
+F2FS_GENERAL_RO_ATTR(queued_discard);
+F2FS_GENERAL_RO_ATTR(undiscard_blks);
+
 static struct attribute *f2fs_stat_attrs[] = {
 	ATTR_LIST(sb_status),
 	ATTR_LIST(cp_status),
+	ATTR_LIST(issued_discard),
+	ATTR_LIST(queued_discard),
+	ATTR_LIST(undiscard_blks),
 	NULL,
 };
 ATTRIBUTE_GROUPS(f2fs_stat);