linux-kernel - [PATCH 1/2] f2fs: add sysfs nodes to get discard information

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Date:   Sun, 15 Aug 2021 01:58:39 +0800
From:   Yangtao Li <frank.li@...o.com>
To:     jaegeuk@...nel.org, chao@...nel.org
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Yangtao Li <frank.li@...o.com>
Subject: [PATCH 1/2] f2fs: add sysfs nodes to get discard information

I've added new sysfs nodes to show discard stat since mount, which
will help us analyze whether the performance problem is related to
discard.

issued_discard  - Shows the number of issued discard
queued_discard  - Shows the number of cached discard cmd count
discard_cmd_cnt - Shows the number of cached discard cmd count
undiscard_blks  - Shows the number of undiscard blocks

Signed-off-by: Yangtao Li <frank.li@...o.com>
---
 Documentation/ABI/testing/sysfs-fs-f2fs | 20 +++++++++++
 fs/f2fs/sysfs.c                         | 44 +++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index ef4b9218ae1e..32df6d16d74f 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -493,3 +493,23 @@ Contact:	"Chao Yu" <yuchao0@...wei.com>
 Description:	When ATGC is on, it controls age threshold to bypass GCing young
 		candidates whose age is not beyond the threshold, by default it was
 		initialized as 604800 seconds (equals to 7 days).
+
+What:		/sys/fs/f2fs/<disk>/issued_discard
+Date:		August 2021
+Contact:	"Yangtao Li" <frank.li@...o.com>
+Description:	Shows the number of issued discard.
+
+What:		/sys/fs/f2fs/<disk>/queued_discard
+Date:		August 2021
+Contact:	"Yangtao Li" <frank.li@...o.com>
+Description:	Shows the number of queued discard.
+
+What:		/sys/fs/f2fs/<disk>/discard_cmd_cnt
+Date:		August 2021
+Contact:	"Yangtao Li" <frank.li@...o.com>
+Description:	Shows the number of cached discard cmd count.
+
+What:		/sys/fs/f2fs/<disk>/undiscard_blks
+Date:		August 2021
+Contact:	"Yangtao Li" <frank.li@...o.com>
+Description:	Shows the number of undiscard blocks.
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 6642246206bd..b7d6c1adc7f8 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -248,6 +248,42 @@ static ssize_t main_blkaddr_show(struct f2fs_attr *a,
 			(unsigned long long)MAIN_BLKADDR(sbi));
 }
 
+static ssize_t issued_discard_show(struct f2fs_attr *a,
+				struct f2fs_sb_info *sbi, char *buf)
+{
+	struct discard_cmd_control *dcc_info = SM_I(sbi)->dcc_info;
+
+	return snprintf(buf, PAGE_SIZE, "%llu\n",
+			(unsigned long long)atomic_read(&dcc_info->issued_discard));
+}
+
+static ssize_t queued_discard_show(struct f2fs_attr *a,
+				struct f2fs_sb_info *sbi, char *buf)
+{
+	struct discard_cmd_control *dcc_info = SM_I(sbi)->dcc_info;
+
+	return snprintf(buf, PAGE_SIZE, "%llu\n",
+			(unsigned long long)atomic_read(&dcc_info->queued_discard));
+}
+
+static ssize_t discard_cmd_cnt_show(struct f2fs_attr *a,
+				struct f2fs_sb_info *sbi, char *buf)
+{
+	struct discard_cmd_control *dcc_info = SM_I(sbi)->dcc_info;
+
+	return snprintf(buf, PAGE_SIZE, "%llu\n",
+			(unsigned long long)atomic_read(&dcc_info->discard_cmd_cnt));
+}
+
+static ssize_t undiscard_blks_show(struct f2fs_attr *a,
+				struct f2fs_sb_info *sbi, char *buf)
+{
+	struct discard_cmd_control *dcc_info = SM_I(sbi)->dcc_info;
+
+	return snprintf(buf, PAGE_SIZE, "%llu\n",
+			(unsigned long long)dcc_info->undiscard_blks);
+}
+
 static ssize_t f2fs_sbi_show(struct f2fs_attr *a,
 			struct f2fs_sb_info *sbi, char *buf)
 {
@@ -690,6 +726,10 @@ F2FS_GENERAL_RO_ATTR(unusable);
 F2FS_GENERAL_RO_ATTR(encoding);
 F2FS_GENERAL_RO_ATTR(mounted_time_sec);
 F2FS_GENERAL_RO_ATTR(main_blkaddr);
+F2FS_GENERAL_RO_ATTR(issued_discard);
+F2FS_GENERAL_RO_ATTR(queued_discard);
+F2FS_GENERAL_RO_ATTR(discard_cmd_cnt);
+F2FS_GENERAL_RO_ATTR(undiscard_blks);
 #ifdef CONFIG_F2FS_STAT_FS
 F2FS_STAT_ATTR(STAT_INFO, f2fs_stat_info, cp_foreground_calls, cp_count);
 F2FS_STAT_ATTR(STAT_INFO, f2fs_stat_info, cp_background_calls, bg_cp_count);
@@ -750,6 +790,10 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(gc_urgent),
 	ATTR_LIST(reclaim_segments),
 	ATTR_LIST(main_blkaddr),
+	ATTR_LIST(issued_discard),
+	ATTR_LIST(queued_discard),
+	ATTR_LIST(discard_cmd_cnt),
+	ATTR_LIST(undiscard_blks),
 	ATTR_LIST(max_small_discards),
 	ATTR_LIST(discard_granularity),
 	ATTR_LIST(batched_trim_sections),
-- 
2.32.0