f2fs-tools: support small RO partition

This patch adds a readonly feature on small partitions by eliminating
on-disk layout for data writes such as provisioning/reserved space and
SSA.

This requires f2fs updates to understand RO feature in superblock.

Tested 4 cases:
 sload.f2fs -c -a lz0 -f kernel/fs $DEV
 sload.f2fs -c -a lz4 -f kernel/fs $DEV
 sload.f2fs -c -r -a lz4 -f kernel/fs $DEV
 sload.f2fs -c -L 3 -r -a lz4 -f kernel/fs $DEV

after:
 mkfs.f2fs -O ro,compression,extra_attr -f $DEV
 fsck.f2fs $DEV

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

8 files changed, 169 insertions, 54 deletions

diff --git a/fsck/fsck.c b/fsck/fsck.c
index 6019775..80a6d8e 100644
--- a/fsck/fsck.c
+++ b/fsck/fsck.c
@@ -144,6 +144,7 @@ static int find_and_dec_hard_link_list(struct f2fs_sb_info *sbi, u32 nid)
 static int is_valid_ssa_node_blk(struct f2fs_sb_info *sbi, u32 nid,
 							u32 blk_addr)
 {
+	struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
 	struct f2fs_summary_block *sum_blk;
 	struct f2fs_summary *sum_entry;
 	struct seg_entry * se;
@@ -151,6 +152,9 @@ static int is_valid_ssa_node_blk(struct f2fs_sb_info *sbi, u32 nid,
 	int need_fix = 0, ret = 0;
 	int type;
 
+	if (get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO))
+		return 0;
+
 	segno = GET_SEGNO(sbi, blk_addr);
 	offset = OFFSET_IN_SEG(sbi, blk_addr);
 
@@ -261,6 +265,7 @@ out:
 static int is_valid_ssa_data_blk(struct f2fs_sb_info *sbi, u32 blk_addr,
 		u32 parent_nid, u16 idx_in_node, u8 version)
 {
+	struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
 	struct f2fs_summary_block *sum_blk;
 	struct f2fs_summary *sum_entry;
 	struct seg_entry * se;
@@ -268,6 +273,9 @@ static int is_valid_ssa_data_blk(struct f2fs_sb_info *sbi, u32 blk_addr,
 	int need_fix = 0, ret = 0;
 	int type;
 
+	if (get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO))
+		return 0;
+
 	segno = GET_SEGNO(sbi, blk_addr);
 	offset = OFFSET_IN_SEG(sbi, blk_addr);
 
@@ -2372,10 +2380,15 @@ static int check_curseg_write_pointer(struct f2fs_sb_info *UNUSED(sbi),
 
 int check_curseg_offset(struct f2fs_sb_info *sbi, int type)
 {
+	struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
 	struct curseg_info *curseg = CURSEG_I(sbi, type);
 	struct seg_entry *se;
 	int j, nblocks;
 
+	if (get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO) &&
+			type != CURSEG_HOT_DATA && type != CURSEG_HOT_NODE)
+		return 0;
+
 	if ((curseg->next_blkoff >> 3) >= SIT_VBLOCK_MAP_SIZE) {
 		ASSERT_MSG("Next block offset:%u is invalid, type:%d",
 			curseg->next_blkoff, type);
@@ -2958,6 +2971,7 @@ void fsck_chk_and_fix_write_pointers(struct f2fs_sb_info *sbi)
 
 int fsck_chk_curseg_info(struct f2fs_sb_info *sbi)
 {
+	struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
 	struct curseg_info *curseg;
 	struct seg_entry *se;
 	struct f2fs_summary_block *sum_blk;
@@ -2968,6 +2982,10 @@ int fsck_chk_curseg_info(struct f2fs_sb_info *sbi)
 		se = get_seg_entry(sbi, curseg->segno);
 		sum_blk = curseg->sum_blk;
 
+		if ((get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO)) &&
+			(i != CURSEG_HOT_DATA && i != CURSEG_HOT_NODE))
+			continue;
+
 		if (se->type != i) {
 			ASSERT_MSG("Incorrect curseg [%d]: segno [0x%x] "
 				   "type(SIT) [%d]", i, curseg->segno,
@@ -3050,7 +3068,10 @@ int fsck_verify(struct f2fs_sb_info *sbi)
 		}
 		c.bug_on = 1;
 	}
-
+	printf("[FSCK] Max image size: %"PRIu64" MB, Free space: %u MB\n",
+		c.max_size >> 20,
+		(sbi->user_block_count - sbi->total_valid_block_count) >>
+		(20 - F2FS_BLKSIZE_BITS));
 	printf("[FSCK] Unreachable nat entries                       ");
 	if (nr_unref_nid == 0x0) {
 		printf(" [Ok..] [0x%x]\n", nr_unref_nid);
diff --git a/fsck/main.c b/fsck/main.c
index 904b09c..c07be1e 100644
--- a/fsck/main.c
+++ b/fsck/main.c
@@ -915,6 +915,11 @@ static int do_defrag(struct f2fs_sb_info *sbi)
 {
 	struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
 
+	if (get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO)) {
+		MSG(0, "Not support on readonly image.\n");
+		return -1;
+	}
+
 	if (c.defrag_start > get_sb(block_count))
 		goto out_range;
 	if (c.defrag_start < SM_I(sbi)->main_blkaddr)
diff --git a/fsck/mount.c b/fsck/mount.c
index f7763c9..de692b6 100644
--- a/fsck/mount.c
+++ b/fsck/mount.c
@@ -568,6 +568,9 @@ void print_sb_state(struct f2fs_super_block *sb)
 	if (f & cpu_to_le32(F2FS_FEATURE_COMPRESSION)) {
 		MSG(0, "%s", " compression");
 	}
+	if (f & cpu_to_le32(F2FS_FEATURE_RO)) {
+		MSG(0, "%s", " ro");
+	}
 	MSG(0, "\n");
 	MSG(0, "Info: superblock encrypt level = %d, salt = ",
 					sb->encryption_level);
@@ -863,9 +866,10 @@ int sanity_check_raw_super(struct f2fs_super_block *sb, enum SB_ADDR sb_addr)
 		return -1;
 	}
 
-	if (total_sections > segment_count ||
+	if (!(get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO)) &&
+			(total_sections > segment_count ||
 			total_sections < F2FS_MIN_SEGMENTS ||
-			segs_per_sec > segment_count || !segs_per_sec) {
+			segs_per_sec > segment_count || !segs_per_sec)) {
 		MSG(0, "\tInvalid segment/section count (%u, %u x %u)\n",
 			segment_count, total_sections, segs_per_sec);
 		return 1;
@@ -1262,14 +1266,16 @@ int sanity_check_ckpt(struct f2fs_sb_info *sbi)
 	ovp_segments = get_cp(overprov_segment_count);
 	reserved_segments = get_cp(rsvd_segment_count);
 
-	if (fsmeta < F2FS_MIN_SEGMENT || ovp_segments == 0 ||
-					reserved_segments == 0) {
+	if (!(get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO)) &&
+		(fsmeta < F2FS_MIN_SEGMENT || ovp_segments == 0 ||
+					reserved_segments == 0)) {
 		MSG(0, "\tWrong layout: check mkfs.f2fs version\n");
 		return 1;
 	}
 
 	user_block_count = get_cp(user_block_count);
-	segment_count_main = get_sb(segment_count_main);
+	segment_count_main = get_sb(segment_count_main) +
+				(cpu_to_le32(F2FS_FEATURE_RO) ? 1 : 0);
 	log_blocks_per_seg = get_sb(log_blocks_per_seg);
 	if (!user_block_count || user_block_count >=
 			segment_count_main << log_blocks_per_seg) {
@@ -1892,11 +1898,15 @@ static void read_normal_summaries(struct f2fs_sb_info *sbi, int type)
 void update_sum_entry(struct f2fs_sb_info *sbi, block_t blk_addr,
 					struct f2fs_summary *sum)
 {
+	struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
 	struct f2fs_summary_block *sum_blk;
 	u32 segno, offset;
 	int type, ret;
 	struct seg_entry *se;
 
+	if (get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO))
+		return;
+
 	segno = GET_SEGNO(sbi, blk_addr);
 	offset = OFFSET_IN_SEG(sbi, blk_addr);
 
@@ -2731,18 +2741,17 @@ int find_next_free_block(struct f2fs_sb_info *sbi, u64 *to, int left,
 		bitmap = get_seg_bitmap(sbi, se);
 		type = get_seg_type(sbi, se);
 
-		if (vblocks == sbi->blocks_per_seg ||
-				IS_CUR_SEGNO(sbi, segno)) {
-			*to = left ? START_BLOCK(sbi, segno) - 1:
-						START_BLOCK(sbi, segno + 1);
-			continue;
-		}
-
-		if (vblocks == 0 && not_enough) {
+		if (vblocks == sbi->blocks_per_seg) {
+next_segment:
 			*to = left ? START_BLOCK(sbi, segno) - 1:
 						START_BLOCK(sbi, segno + 1);
 			continue;
 		}
+		if (!(get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO)) &&
+						IS_CUR_SEGNO(sbi, segno))
+			goto next_segment;
+		if (vblocks == 0 && not_enough)
+			goto next_segment;
 
 		if (vblocks == 0 && !(segno % sbi->segs_per_sec)) {
 			struct seg_entry *se2;
@@ -2773,17 +2782,24 @@ int find_next_free_block(struct f2fs_sb_info *sbi, u64 *to, int left,
 static void move_one_curseg_info(struct f2fs_sb_info *sbi, u64 from, int left,
 				 int i)
 {
+	struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
 	struct curseg_info *curseg = CURSEG_I(sbi, i);
 	struct f2fs_summary_block buf;
 	u32 old_segno;
 	u64 ssa_blk, to;
 	int ret;
 
+	if ((get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO))) {
+		if (i != CURSEG_HOT_DATA && i != CURSEG_HOT_NODE)
+			return;
+		goto bypass_ssa;
+	}
+
 	/* update original SSA too */
 	ssa_blk = GET_SUM_BLKADDR(sbi, curseg->segno);
 	ret = dev_write_block(curseg->sum_blk, ssa_blk);
 	ASSERT(ret >= 0);
-
+bypass_ssa:
 	to = from;
 	ret = find_next_free_block(sbi, &to, left, i,
 				   c.zoned_model == F2FS_ZONED_HM);
@@ -3022,10 +3038,12 @@ void write_checkpoint(struct f2fs_sb_info *sbi)
 		ret = dev_write_block(curseg->sum_blk, cp_blk_no++);
 		ASSERT(ret >= 0);
 
-		/* update original SSA too */
-		ssa_blk = GET_SUM_BLKADDR(sbi, curseg->segno);
-		ret = dev_write_block(curseg->sum_blk, ssa_blk);
-		ASSERT(ret >= 0);
+		if (!(get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO))) {
+			/* update original SSA too */
+			ssa_blk = GET_SUM_BLKADDR(sbi, curseg->segno);
+			ret = dev_write_block(curseg->sum_blk, ssa_blk);
+			ASSERT(ret >= 0);
+		}
 	}
 
 	/* Write nat bits */
diff --git a/fsck/node.c b/fsck/node.c
index 1d291ca..c7988cb 100644
--- a/fsck/node.c
+++ b/fsck/node.c
@@ -61,6 +61,7 @@ void set_data_blkaddr(struct dnode_of_data *dn)
 block_t new_node_block(struct f2fs_sb_info *sbi,
 				struct dnode_of_data *dn, unsigned int ofs)
 {
+	struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
 	struct f2fs_node *f2fs_inode;
 	struct f2fs_node *node_blk;
 	struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
@@ -89,6 +90,10 @@ block_t new_node_block(struct f2fs_sb_info *sbi,
 			type = CURSEG_WARM_NODE;
 	}
 
+	if ((get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO)) &&
+					type != CURSEG_HOT_NODE)
+		type = CURSEG_HOT_NODE;
+
 	get_node_info(sbi, dn->nid, &ni);
 	set_summary(&sum, dn->nid, 0, ni.version);
 	ret = reserve_new_block(sbi, &blkaddr, &sum, type, !ofs);
diff --git a/fsck/segment.c b/fsck/segment.c
index 365c7f8..0b25736 100644
--- a/fsck/segment.c
+++ b/fsck/segment.c
@@ -104,11 +104,16 @@ int reserve_new_block(struct f2fs_sb_info *sbi, block_t *to,
 int new_data_block(struct f2fs_sb_info *sbi, void *block,
 				struct dnode_of_data *dn, int type)
 {
+	struct f2fs_super_block *sb = F2FS_RAW_SUPER(sbi);
 	struct f2fs_summary sum;
 	struct node_info ni;
 	unsigned int blkaddr = datablock_addr(dn->node_blk, dn->ofs_in_node);
 	int ret;
 
+	if ((get_sb(feature) & cpu_to_le32(F2FS_FEATURE_RO)) &&
+					type != CURSEG_HOT_DATA)
+		type = CURSEG_HOT_DATA;
+
 	ASSERT(dn->node_blk);
 	memset(block, 0, BLOCK_SZ);
 
diff --git a/include/f2fs_fs.h b/include/f2fs_fs.h
index 66547a3..4c1d06c 100644
--- a/include/f2fs_fs.h
+++ b/include/f2fs_fs.h
@@ -458,6 +458,7 @@ struct f2fs_configuration {
 	u_int64_t wanted_total_sectors;
 	u_int64_t wanted_sector_size;
 	u_int64_t target_sectors;
+	u_int64_t max_size;
 	u_int32_t sectors_per_blk;
 	u_int32_t blks_per_seg;
 	__u8 init_version[VERSION_LEN + 1];
@@ -716,7 +717,8 @@ enum {
 #define F2FS_FEATURE_VERITY		0x0400	/* reserved */
 #define F2FS_FEATURE_SB_CHKSUM		0x0800
 #define F2FS_FEATURE_CASEFOLD		0x1000
- #define F2FS_FEATURE_COMPRESSION	0x2000
+#define F2FS_FEATURE_COMPRESSION	0x2000
+#define F2FS_FEATURE_RO			0x4000
 
 #define MAX_VOLUME_NAME		512
 
@@ -1566,6 +1568,7 @@ struct feature feature_table[] = {					\
 	{ "sb_checksum",		F2FS_FEATURE_SB_CHKSUM },	\
 	{ "casefold",			F2FS_FEATURE_CASEFOLD },	\
 	{ "compression",		F2FS_FEATURE_COMPRESSION },	\
+	{ "ro",				F2FS_FEATURE_RO},		\
 	{ NULL,				0x0},				\
 };
 
diff --git a/lib/libf2fs_io.c b/lib/libf2fs_io.c
index dcedc17..320ee6c 100644
--- a/lib/libf2fs_io.c
+++ b/lib/libf2fs_io.c
@@ -507,6 +507,9 @@ int dev_read(void *buf, __u64 offset, size_t len)
 	int fd;
 	int err;
 
+	if (c.max_size < (offset + len))
+		c.max_size = offset + len;
+
 	if (c.sparse_mode)
 		return sparse_read_blk(offset / F2FS_BLKSIZE,
 					len / F2FS_BLKSIZE, buf);
@@ -548,6 +551,9 @@ int dev_write(void *buf, __u64 offset, size_t len)
 {
 	int fd;
 
+	if (c.max_size < (offset + len))
+		c.max_size = offset + len;
+
 	if (c.dry_run)
 		return 0;
 
@@ -590,6 +596,9 @@ int dev_fill(void *buf, __u64 offset, size_t len)
 {
 	int fd;
 
+	if (c.max_size < (offset + len))
+		c.max_size = offset + len;
+
 	if (c.sparse_mode)
 		return sparse_write_zeroed_blk(offset / F2FS_BLKSIZE,
 						len / F2FS_BLKSIZE);
diff --git a/mkfs/f2fs_format.c b/mkfs/f2fs_format.c
index fbecb05..3565bd3 100644
--- a/mkfs/f2fs_format.c
+++ b/mkfs/f2fs_format.c
@@ -212,7 +212,7 @@ static int f2fs_prepare_super_block(void)
 	u_int64_t total_meta_zones, total_meta_segments;
 	u_int32_t sit_bitmap_size, max_sit_bitmap_size;
 	u_int32_t max_nat_bitmap_size, max_nat_segments;
-	u_int32_t total_zones;
+	u_int32_t total_zones, avail_zones;
 	enum quota_type qtype;
 	int i;
 
@@ -250,6 +250,9 @@ static int f2fs_prepare_super_block(void)
 		zone_size_bytes * zone_size_bytes -
 		(u_int64_t) c.start_sector * DEFAULT_SECTOR_SIZE;
 
+	if (c.feature & cpu_to_le32(F2FS_FEATURE_RO))
+		zone_align_start_offset = 8192;
+
 	if (c.start_sector % DEFAULT_SECTORS_PER_BLOCK) {
 		MSG(1, "\t%s: Align start sector number to the page unit\n",
 				c.zoned_mode ? "FAIL" : "WARN");
@@ -400,7 +403,10 @@ static int f2fs_prepare_super_block(void)
 			get_sb(segment_count_nat))) *
 			c.blks_per_seg;
 
-	blocks_for_ssa = total_valid_blks_available /
+	if (c.feature & cpu_to_le32(F2FS_FEATURE_RO))
+		blocks_for_ssa = 0;
+	else
+		blocks_for_ssa = total_valid_blks_available /
 				c.blks_per_seg + 1;
 
 	set_sb(segment_count_ssa, SEG_ALIGN(blocks_for_ssa));
@@ -457,7 +463,13 @@ static int f2fs_prepare_super_block(void)
 			(2 * (100 / c.overprovision + 1) + NR_CURSEG_TYPE) *
 			round_up(f2fs_get_usable_segments(sb), get_sb(section_count));
 
-	if (c.overprovision == 0 || c.total_segments < F2FS_MIN_SEGMENTS ||
+	if (c.feature & cpu_to_le32(F2FS_FEATURE_RO)) {
+		c.overprovision = 0;
+		c.reserved_segments = 0;
+	}
+	if ((!(c.feature & cpu_to_le32(F2FS_FEATURE_RO)) &&
+		c.overprovision == 0) ||
+		c.total_segments < F2FS_MIN_SEGMENTS ||
 		(c.devices[0].total_sectors *
 			c.sector_size < zone_align_start_offset) ||
 		(get_sb(segment_count_main) - NR_CURSEG_TYPE) <
@@ -503,13 +515,25 @@ static int f2fs_prepare_super_block(void)
 	if (c.feature & cpu_to_le32(F2FS_FEATURE_LOST_FOUND))
 		c.lpf_ino = c.next_free_nid++;
 
-	if (total_zones <= 6) {
+	if (c.feature & cpu_to_le32(F2FS_FEATURE_RO))
+		avail_zones = 2;
+	else
+		avail_zones = 6;
+
+	if (total_zones <= avail_zones) {
 		MSG(1, "\tError: %d zones: Need more zones "
 			"by shrinking zone size\n", total_zones);
 		return -1;
 	}
 
-	if (c.heap) {
+	if (c.feature & cpu_to_le32(F2FS_FEATURE_RO)) {
+		c.cur_seg[CURSEG_HOT_NODE] = 0;
+		c.cur_seg[CURSEG_WARM_NODE] = 0;
+		c.cur_seg[CURSEG_COLD_NODE] = 0;
+		c.cur_seg[CURSEG_HOT_DATA] = 1;
+		c.cur_seg[CURSEG_COLD_DATA] = 0;
+		c.cur_seg[CURSEG_WARM_DATA] = 0;
+	} else if (c.heap) {
 		c.cur_seg[CURSEG_HOT_NODE] =
 				last_section(last_zone(total_zones));
 		c.cur_seg[CURSEG_WARM_NODE] = prev_zone(CURSEG_HOT_NODE);
@@ -538,7 +562,8 @@ static int f2fs_prepare_super_block(void)
 	}
 
 	/* if there is redundancy, reassign it */
-	verify_cur_segs();
+	if (!(c.feature & cpu_to_le32(F2FS_FEATURE_RO)))
+		verify_cur_segs();
 
 	cure_extension_list();
 
@@ -731,9 +756,15 @@ static int f2fs_write_check_point_pack(void)
 					c.reserved_segments);
 
 	/* main segments - reserved segments - (node + data segments) */
-	set_cp(free_segment_count, f2fs_get_usable_segments(sb) - 6);
-	set_cp(user_block_count, ((get_cp(free_segment_count) + 6 -
+	if (c.feature & cpu_to_le32(F2FS_FEATURE_RO)) {
+		set_cp(free_segment_count, f2fs_get_usable_segments(sb) - 2);
+		set_cp(user_block_count, ((get_cp(free_segment_count) + 2 -
 			get_cp(overprov_segment_count)) * c.blks_per_seg));
+	} else {
+		set_cp(free_segment_count, f2fs_get_usable_segments(sb) - 6);
+		set_cp(user_block_count, ((get_cp(free_segment_count) + 6 -
+			get_cp(overprov_segment_count)) * c.blks_per_seg));
+	}
 	/* cp page (2), data summaries (1), node summaries (3) */
 	set_cp(cp_pack_total_block_count, 6 + get_sb(cp_payload));
 	flags = CP_UMOUNT_FLAG | CP_COMPACT_SUM_FLAG;
@@ -847,8 +878,13 @@ static int f2fs_write_check_point_pack(void)
 	sum_compact_p += SUM_JOURNAL_SIZE;
 
 	memset(sum, 0, sizeof(struct f2fs_summary_block));
+
 	/* inode sit for root */
-	journal->n_sits = cpu_to_le16(6);
+	if (c.feature & cpu_to_le32(F2FS_FEATURE_RO))
+		journal->n_sits = cpu_to_le16(2);
+	else
+		journal->n_sits = cpu_to_le16(6);
+
 	journal->sit_j.entries[0].segno = cp->cur_node_segno[0];
 	journal->sit_j.entries[0].se.vblocks =
 				cpu_to_le16((CURSEG_HOT_NODE << 10) |
@@ -859,30 +895,43 @@ static int f2fs_write_check_point_pack(void)
 	if (c.lpf_inum)
 		f2fs_set_bit(i, (char *)journal->sit_j.entries[0].se.valid_map);
 
-	journal->sit_j.entries[1].segno = cp->cur_node_segno[1];
-	journal->sit_j.entries[1].se.vblocks =
-				cpu_to_le16((CURSEG_WARM_NODE << 10));
-	journal->sit_j.entries[2].segno = cp->cur_node_segno[2];
-	journal->sit_j.entries[2].se.vblocks =
-				cpu_to_le16((CURSEG_COLD_NODE << 10));
-
-	/* data sit for root */
-	journal->sit_j.entries[3].segno = cp->cur_data_segno[0];
-	journal->sit_j.entries[3].se.vblocks =
-				cpu_to_le16((CURSEG_HOT_DATA << 10) |
-						(1 + c.quota_dnum + c.lpf_dnum));
-	f2fs_set_bit(0, (char *)journal->sit_j.entries[3].se.valid_map);
-	for (i = 1; i <= c.quota_dnum; i++)
-		f2fs_set_bit(i, (char *)journal->sit_j.entries[3].se.valid_map);
-	if (c.lpf_dnum)
-		f2fs_set_bit(i, (char *)journal->sit_j.entries[3].se.valid_map);
-
-	journal->sit_j.entries[4].segno = cp->cur_data_segno[1];
-	journal->sit_j.entries[4].se.vblocks =
-				cpu_to_le16((CURSEG_WARM_DATA << 10));
-	journal->sit_j.entries[5].segno = cp->cur_data_segno[2];
-	journal->sit_j.entries[5].se.vblocks =
-				cpu_to_le16((CURSEG_COLD_DATA << 10));
+	if (c.feature & cpu_to_le32(F2FS_FEATURE_RO)) {
+		/* data sit for root */
+		journal->sit_j.entries[1].segno = cp->cur_data_segno[0];
+		journal->sit_j.entries[1].se.vblocks =
+					cpu_to_le16((CURSEG_HOT_DATA << 10) |
+							(1 + c.quota_dnum + c.lpf_dnum));
+		f2fs_set_bit(0, (char *)journal->sit_j.entries[1].se.valid_map);
+		for (i = 1; i <= c.quota_dnum; i++)
+			f2fs_set_bit(i, (char *)journal->sit_j.entries[1].se.valid_map);
+		if (c.lpf_dnum)
+			f2fs_set_bit(i, (char *)journal->sit_j.entries[1].se.valid_map);
+	} else {
+		journal->sit_j.entries[1].segno = cp->cur_node_segno[1];
+		journal->sit_j.entries[1].se.vblocks =
+					cpu_to_le16((CURSEG_WARM_NODE << 10));
+		journal->sit_j.entries[2].segno = cp->cur_node_segno[2];
+		journal->sit_j.entries[2].se.vblocks =
+					cpu_to_le16((CURSEG_COLD_NODE << 10));
+
+		/* data sit for root */
+		journal->sit_j.entries[3].segno = cp->cur_data_segno[0];
+		journal->sit_j.entries[3].se.vblocks =
+					cpu_to_le16((CURSEG_HOT_DATA << 10) |
+							(1 + c.quota_dnum + c.lpf_dnum));
+		f2fs_set_bit(0, (char *)journal->sit_j.entries[3].se.valid_map);
+		for (i = 1; i <= c.quota_dnum; i++)
+			f2fs_set_bit(i, (char *)journal->sit_j.entries[3].se.valid_map);
+		if (c.lpf_dnum)
+			f2fs_set_bit(i, (char *)journal->sit_j.entries[3].se.valid_map);
+
+		journal->sit_j.entries[4].segno = cp->cur_data_segno[1];
+		journal->sit_j.entries[4].se.vblocks =
+					cpu_to_le16((CURSEG_WARM_DATA << 10));
+		journal->sit_j.entries[5].segno = cp->cur_data_segno[2];
+		journal->sit_j.entries[5].se.vblocks =
+					cpu_to_le16((CURSEG_COLD_DATA << 10));
+	}
 
 	memcpy(sum_compact_p, &journal->n_sits, SUM_JOURNAL_SIZE);
 	sum_compact_p += SUM_JOURNAL_SIZE;
@@ -1090,7 +1139,7 @@ static int f2fs_discard_obsolete_dnode(void)
 	u_int64_t start_inode_pos = get_sb(main_blkaddr);
 	u_int64_t last_inode_pos;
 
-	if (c.zoned_mode)
+	if (c.zoned_mode || c.feature & cpu_to_le32(F2FS_FEATURE_RO))
 		return 0;
 
 	raw_node = calloc(sizeof(struct f2fs_node), 1);