f2fs: atgc: export entries for better tunability via sysfs

This patch export below sysfs entries for better ATGC tunability.

/sys/fs/f2fs/<disk>/atgc_candidate_ratio
/sys/fs/f2fs/<disk>/atgc_candidate_count
/sys/fs/f2fs/<disk>/atgc_age_weight
/sys/fs/f2fs/<disk>/atgc_age_threshold
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -438,3 +438,31 @@ Description:	Show the count of inode newly enabled for compression since mount.
 		Note that when the compression is disabled for the files, this count
 		doesn't decrease. If you write "0" here, you can initialize
 		compr_new_inode to "0".
+
+What:		/sys/fs/f2fs/<disk>/atgc_candidate_ratio
+Date:		May 2021
+Contact:	"Chao Yu" <yuchao0@huawei.com>
+Description:	When ATGC is on, it controls candidate ratio in order to limit total
+		number of potential victim in all candidates, the value should be in
+		range of [0, 100], by default it was initialized as 20(%).
+
+What:		/sys/fs/f2fs/<disk>/atgc_candidate_count
+Date:		May 2021
+Contact:	"Chao Yu" <yuchao0@huawei.com>
+Description:	When ATGC is on, it controls candidate count in order to limit total
+		number of potential victim in all candidates, by default it was
+		initialized as 10 (sections).
+
+What:		/sys/fs/f2fs/<disk>/atgc_age_weight
+Date:		May 2021
+Contact:	"Chao Yu" <yuchao0@huawei.com>
+Description:	When ATGC is on, it controls age weight to balance weight proportion
+		in between aging and valid blocks, the value should be in range of
+		[0, 100], by default it was initialized as 60(%).
+
+What:		/sys/fs/f2fs/<disk>/atgc_age_threshold
+Date:		May 2021
+Contact:	"Chao Yu" <yuchao0@huawei.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).

fs/f2fs/sysfs.c

@@ -37,6 +37,7 @@ enum {
 #endif
 	RESERVED_BLOCKS,	/* struct f2fs_sb_info */
 	CPRC_INFO,	/* struct ckpt_req_control */
+	ATGC_INFO,	/* struct atgc_management */
 };
 
 struct f2fs_attr {
@@ -75,6 +76,8 @@ static unsigned char *__struct_ptr(struct f2fs_sb_info *sbi, int struct_type)
 #endif
 	else if (struct_type == CPRC_INFO)
 		return (unsigned char *)&sbi->cprc_info;
+	else if (struct_type == ATGC_INFO)
+		return (unsigned char *)&sbi->am;
 	return NULL;
 }
 
@@ -495,6 +498,20 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 	}
 #endif
 
+	if (!strcmp(a->attr.name, "atgc_candidate_ratio")) {
+		if (t > 100)
+			return -EINVAL;
+		sbi->am.candidate_ratio = t;
+		return count;
+	}
+
+	if (!strcmp(a->attr.name, "atgc_age_weight")) {
+		if (t > 100)
+			return -EINVAL;
+		sbi->am.age_weight = t;
+		return count;
+	}
+
 	*ui = (unsigned int)t;
 
 	return count;
@@ -710,6 +727,11 @@ F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, compr_written_block, compr_written_block);
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, compr_saved_block, compr_saved_block);
 F2FS_RW_ATTR(F2FS_SBI, f2fs_sb_info, compr_new_inode, compr_new_inode);
 #endif
+/* For ATGC */
+F2FS_RW_ATTR(ATGC_INFO, atgc_management, atgc_candidate_ratio, candidate_ratio);
+F2FS_RW_ATTR(ATGC_INFO, atgc_management, atgc_candidate_count, max_candidate_count);
+F2FS_RW_ATTR(ATGC_INFO, atgc_management, atgc_age_weight, age_weight);
+F2FS_RW_ATTR(ATGC_INFO, atgc_management, atgc_age_threshold, age_threshold);
 
 #define ATTR_LIST(name) (&f2fs_attr_##name.attr)
 static struct attribute *f2fs_attrs[] = {
@@ -778,6 +800,11 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(compr_saved_block),
 	ATTR_LIST(compr_new_inode),
 #endif
+	/* For ATGC */
+	ATTR_LIST(atgc_candidate_ratio),
+	ATTR_LIST(atgc_candidate_count),
+	ATTR_LIST(atgc_age_weight),
+	ATTR_LIST(atgc_age_threshold),
 	NULL,
 };
 ATTRIBUTE_GROUPS(f2fs);