[PATCH 2/2] f2fs: introduce gc_mode sysfs node

[Yangtao Li <frank.li@vivo.com>]

gc_mode sysfs node can show the current gc_mode as a string.
Introducing it increases readability.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
---
 Documentation/ABI/testing/sysfs-fs-f2fs |  6 ++++++
 fs/f2fs/f2fs.h                          |  1 +
 fs/f2fs/sysfs.c                         | 18 ++++++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index 483639fb727b..6466f3b1f0a9 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -634,3 +634,9 @@ Date:		July 2022
 Contact:	"Daeho Jeong" <daehojeong@google.com>
 Description:	Show the accumulated total revoked atomic write block count after boot.
 		If you write "0" here, you can initialize to "0".
+
+What:		/sys/fs/f2fs/<disk>/gc_mode
+Date:		October 2022
+Contact:	"Yangtao Li" <frank.li@vivo.com>
+Description:	Show the current gc_mode as a string.
+		This is a read-only entry.
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index e6355a5683b7..80f23e44a442 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1318,6 +1318,7 @@ enum {
 	MAX_TIME,
 };
 
+/* Note that you need to keep synchronization with this gc_mode_names array */
 enum {
 	GC_NORMAL,
 	GC_IDLE_CB,
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 49898a7243ba..058857d8b3b9 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -41,6 +41,16 @@ enum {
 	ATGC_INFO,	/* struct atgc_management */
 };
 
+static const char *gc_mode_names[MAX_GC_MODE] = {
+		"GC_NORMAL",
+		"GC_IDLE_CB",
+		"GC_IDLE_GREEDY",
+		"GC_IDLE_AT",
+		"GC_URGENT_HIGH",
+		"GC_URGENT_LOW",
+		"GC_URGENT_MID"
+};
+
 struct f2fs_attr {
 	struct attribute attr;
 	ssize_t (*show)(struct f2fs_attr *, struct f2fs_sb_info *, char *);
@@ -133,6 +143,12 @@ static ssize_t pending_discard_show(struct f2fs_attr *a,
 				&SM_I(sbi)->dcc_info->discard_cmd_cnt));
 }
 
+static ssize_t gc_mode_show(struct f2fs_attr *a,
+		struct f2fs_sb_info *sbi, char *buf)
+{
+	return sprintf(buf, "%s\n", gc_mode_names[sbi->gc_mode]);
+}
+
 static ssize_t features_show(struct f2fs_attr *a,
 		struct f2fs_sb_info *sbi, char *buf)
 {
@@ -823,6 +839,7 @@ F2FS_GENERAL_RO_ATTR(encoding);
 F2FS_GENERAL_RO_ATTR(mounted_time_sec);
 F2FS_GENERAL_RO_ATTR(main_blkaddr);
 F2FS_GENERAL_RO_ATTR(pending_discard);
+F2FS_GENERAL_RO_ATTR(gc_mode);
 #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);
@@ -904,6 +921,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(max_discard_issue_time),
 	ATTR_LIST(discard_granularity),
 	ATTR_LIST(pending_discard),
+	ATTR_LIST(gc_mode),
 	ATTR_LIST(batched_trim_sections),
 	ATTR_LIST(ipu_policy),
 	ATTR_LIST(min_ipu_util),
-- 
2.25.1