[PATCH V2] f2fs: show more discard status by sysfs

[Zhiguo Niu]

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@xxxxxxxxxx>
---
changes of v2: Improve the patch according to Chao's suggestions.
---
---
 Documentation/ABI/testing/sysfs-fs-f2fs |  6 ++++++
 fs/f2fs/sysfs.c                         | 18 ++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index 36c3cb5..c6970e5 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -498,6 +498,12 @@ Description:	Show status of f2fs checkpoint in real time.
 		CP_RESIZEFS_FLAG		0x00004000
 		=============================== ==============================
 
+What:		/sys/fs/f2fs/<disk>/stat/discard_status
+Date:		November 2023
+Contact:	"Zhiguo Niu" <zhiguo.niu@xxxxxxxxxx>
+Description:	Show status of f2fs discard in real time, including
+		"issued discard","queued discard" and "undiscard blocks".
+
 What:		/sys/fs/f2fs/<disk>/ckpt_thread_ioprio
 Date:		January 2021
 Contact:	"Daeho Jeong" <daehojeong@xxxxxxxxxx>
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 417fae96..2b80116 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -134,6 +134,22 @@ static ssize_t cp_status_show(struct f2fs_attr *a,
 	return sysfs_emit(buf, "%x\n", le32_to_cpu(F2FS_CKPT(sbi)->ckpt_flags));
 }
 
+static ssize_t discard_status_show(struct f2fs_attr *a,
+		struct f2fs_sb_info *sbi, char *buf)
+{
+	struct discard_cmd_control *dcc = SM_I(sbi)->dcc_info;
+
+	if (!dcc)
+		return -EINVAL;
+
+	return sysfs_emit(buf, "%llu, %llu, %u\n",
+			(unsigned long long)atomic_read(
+				&dcc->issued_discard),
+			(unsigned long long)atomic_read(
+				&dcc->queued_discard),
+			dcc->undiscard_blks);
+}
+
 static ssize_t pending_discard_show(struct f2fs_attr *a,
 		struct f2fs_sb_info *sbi, char *buf)
 {
@@ -1197,9 +1213,11 @@ static ssize_t f2fs_sb_feature_show(struct f2fs_attr *a,
 
 F2FS_GENERAL_RO_ATTR(sb_status);
 F2FS_GENERAL_RO_ATTR(cp_status);
+F2FS_GENERAL_RO_ATTR(discard_status);
 static struct attribute *f2fs_stat_attrs[] = {
 	ATTR_LIST(sb_status),
 	ATTR_LIST(cp_status),
+	ATTR_LIST(discard_status),
 	NULL,
 };
 ATTRIBUTE_GROUPS(f2fs_stat);
-- 
1.9.1