f2fs: introduce max_ordered_discard sysfs node

The current max_ordered_discard is a fixed value, change it to be
configurable through the sys node.
Signed-off-by: Yangtao Li <frank.li@vivo.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

Documentation/ABI/testing/sysfs-fs-f2fs

@@ -99,6 +99,12 @@ Description:	Controls the issue rate of discard commands that consist of small
 		checkpoint is triggered, and issued during the checkpoint.
 		By default, it is disabled with 0.
 
+What:		/sys/fs/f2fs/<disk>/max_ordered_discard
+Date:		October 2022
+Contact:	"Yangtao Li" <frank.li@vivo.com>
+Description:	Controls the maximum ordered discard, the unit size is one block(4KB).
+		Set it to 16 by default.
+
 What:		/sys/fs/f2fs/<disk>/max_discard_request
 Date:		December 2021
 Contact:	"Konstantin Vyshetsky" <vkon@google.com>

fs/f2fs/f2fs.h

@@ -331,6 +331,8 @@ struct discard_entry {
 
 /* default discard granularity of inner discard thread, unit: block count */
 #define DEFAULT_DISCARD_GRANULARITY		16
+/* default maximum discard granularity of ordered discard, unit: block count */
+#define DEFAULT_MAX_ORDERED_DISCARD_GRANULARITY	16
 
 /* max discard pend list number */
 #define MAX_PLIST_NUM		512
@@ -410,6 +412,7 @@ struct discard_cmd_control {
 	unsigned int mid_discard_issue_time;	/* mid. interval between discard issue */
 	unsigned int max_discard_issue_time;	/* max. interval between discard issue */
 	unsigned int discard_granularity;	/* discard granularity */
+	unsigned int max_ordered_discard;	/* maximum discard granularity issued by lba order */
 	unsigned int undiscard_blks;		/* # of undiscard blocks */
 	unsigned int next_pos;			/* next discard position */
 	atomic_t issued_discard;		/* # of issued discard */

fs/f2fs/segment.c

@@ -1448,7 +1448,7 @@ static int __issue_discard_cmd(struct f2fs_sb_info *sbi,
 		if (i + 1 < dpolicy->granularity)
 			break;
 
-		if (i + 1 < DEFAULT_DISCARD_GRANULARITY && dpolicy->ordered)
+		if (i + 1 < dcc->max_ordered_discard && dpolicy->ordered)
 			return __issue_discard_cmd_orderly(sbi, dpolicy);
 
 		pend_list = &dcc->pend_list[i];
@@ -2048,6 +2048,7 @@ static int create_discard_cmd_control(struct f2fs_sb_info *sbi)
 		return -ENOMEM;
 
 	dcc->discard_granularity = DEFAULT_DISCARD_GRANULARITY;
+	dcc->max_ordered_discard = DEFAULT_MAX_ORDERED_DISCARD_GRANULARITY;
 	if (F2FS_OPTION(sbi).discard_unit == DISCARD_UNIT_SEGMENT)
 		dcc->discard_granularity = sbi->blocks_per_seg;
 	else if (F2FS_OPTION(sbi).discard_unit == DISCARD_UNIT_SECTION)

fs/f2fs/sysfs.c

@@ -483,6 +483,15 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 		return count;
 	}
 
+	if (!strcmp(a->attr.name, "max_ordered_discard")) {
+		if (t == 0 || t > MAX_PLIST_NUM)
+			return -EINVAL;
+		if (!f2fs_block_unit_discard(sbi))
+			return -EINVAL;
+		*ui = t;
+		return count;
+	}
+
 	if (!strcmp(a->attr.name, "migration_granularity")) {
 		if (t == 0 || t > sbi->segs_per_sec)
 			return -EINVAL;
@@ -786,6 +795,7 @@ F2FS_RW_ATTR(DCC_INFO, discard_cmd_control, min_discard_issue_time, min_discard_
 F2FS_RW_ATTR(DCC_INFO, discard_cmd_control, mid_discard_issue_time, mid_discard_issue_time);
 F2FS_RW_ATTR(DCC_INFO, discard_cmd_control, max_discard_issue_time, max_discard_issue_time);
 F2FS_RW_ATTR(DCC_INFO, discard_cmd_control, discard_granularity, discard_granularity);
+F2FS_RW_ATTR(DCC_INFO, discard_cmd_control, max_ordered_discard, max_ordered_discard);
 F2FS_RW_ATTR(RESERVED_BLOCKS, f2fs_sb_info, reserved_blocks, reserved_blocks);
 F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, ipu_policy, ipu_policy);
 F2FS_RW_ATTR(SM_INFO, f2fs_sm_info, min_ipu_util, min_ipu_util);
@@ -914,6 +924,7 @@ static struct attribute *f2fs_attrs[] = {
 	ATTR_LIST(mid_discard_issue_time),
 	ATTR_LIST(max_discard_issue_time),
 	ATTR_LIST(discard_granularity),
+	ATTR_LIST(max_ordered_discard),
 	ATTR_LIST(pending_discard),
 	ATTR_LIST(ipu_policy),
 	ATTR_LIST(min_ipu_util),