[RFC PATCH v2 3/3] f2fs-tools: introduce sb checksum

[Junling Zheng <zhengjunling@huawei.com>]

This patch introduced superblock checksum.

Signed-off-by: Junling Zheng <zhengjunling@huawei.com>
---
v1 -> v2:
 - Rename CHKSUM_OFFSET_SB to SB_CHKSUM_OFFSET.
 - Introduce update_sb_chksum() to update superblock checksum.
 fsck/fsck.h        |  1 +
 fsck/mount.c       | 44 ++++++++++++++++++++++++++++++++++++++++++++
 fsck/resize.c      |  3 +++
 include/f2fs_fs.h  |  6 +++++-
 mkfs/f2fs_format.c |  9 +++++++++
 5 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/fsck/fsck.h b/fsck/fsck.h
index 6042e68..2172cac 100644
--- a/fsck/fsck.h
+++ b/fsck/fsck.h
@@ -170,6 +170,7 @@ extern int fsck_verify(struct f2fs_sb_info *);
 extern void fsck_free(struct f2fs_sb_info *);
 extern int f2fs_do_mount(struct f2fs_sb_info *);
 extern void f2fs_do_umount(struct f2fs_sb_info *);
+extern void update_sb_chksum(struct f2fs_super_block *);
 
 extern void flush_journal_entries(struct f2fs_sb_info *);
 extern void zero_journal_entries(struct f2fs_sb_info *);
diff --git a/fsck/mount.c b/fsck/mount.c
index 58ef3e6..1dfabba 100644
--- a/fsck/mount.c
+++ b/fsck/mount.c
@@ -340,6 +340,7 @@ void print_raw_sb_info(struct f2fs_super_block *sb)
 	DISP_u32(sb, node_ino);
 	DISP_u32(sb, meta_ino);
 	DISP_u32(sb, cp_payload);
+	DISP_u32(sb, crc);
 	DISP("%-.256s", sb, version);
 	printf("\n");
 }
@@ -467,6 +468,9 @@ void print_sb_state(struct f2fs_super_block *sb)
 	if (f & cpu_to_le32(F2FS_FEATURE_LOST_FOUND)) {
 		MSG(0, "%s", " lost_found");
 	}
+	if (f & cpu_to_le32(F2FS_FEATURE_SB_CHKSUM)) {
+		MSG(0, "%s", " sb_checksum");
+	}
 	MSG(0, "\n");
 	MSG(0, "Info: superblock encrypt level = %d, salt = ",
 					sb->encryption_level);
@@ -558,10 +562,29 @@ static inline int sanity_check_area_boundary(struct f2fs_super_block *sb,
 	return 0;
 }
 
+static int verify_sb_chksum(struct f2fs_super_block *sb)
+{
+	if (SB_CHKSUM_OFFSET != get_sb(checksum_offset)) {
+		MSG(0, "\tInvalid SB CRC offset: %u\n",
+					get_sb(checksum_offset));
+		return -1;
+	}
+	if (f2fs_crc_valid(get_sb(crc), sb,
+			get_sb(checksum_offset))) {
+		MSG(0, "\tInvalid SB CRC: 0x%x\n", get_sb(crc));
+		return -1;
+	}
+	return 0;
+}
+
 int sanity_check_raw_super(struct f2fs_super_block *sb, u64 offset)
 {
 	unsigned int blocksize;
 
+	if ((get_sb(feature) & F2FS_FEATURE_SB_CHKSUM) &&
+					verify_sb_chksum(sb))
+		return -1;
+
 	if (F2FS_SUPER_MAGIC != get_sb(magic))
 		return -1;
 
@@ -605,6 +628,18 @@ int sanity_check_raw_super(struct f2fs_super_block *sb, u64 offset)
 	return 0;
 }
 
+void update_sb_chksum(struct f2fs_super_block *sb)
+{
+	u32 old_crc, new_crc;
+
+	old_crc = get_sb(crc);
+	new_crc = f2fs_cal_crc32(F2FS_SUPER_MAGIC, sb,
+					SB_CHKSUM_OFFSET);
+	set_sb(crc, new_crc);
+	MSG(0, "Info: update SB CRC successfully "
+		"(0x%x --> 0x%x)\n", old_crc, new_crc);
+}
+
 int validate_super_block(struct f2fs_sb_info *sbi, int block)
 {
 	u64 offset;
@@ -646,6 +681,10 @@ int validate_super_block(struct f2fs_sb_info *sbi, int block)
 
 			memcpy(sbi->raw_super->version,
 						c.version, VERSION_LEN);
+			if (le32_to_cpu(sbi->raw_super->feature) &
+						F2FS_FEATURE_SB_CHKSUM)
+				update_sb_chksum(sbi->raw_super);
+
 			ret = dev_write(sbi->raw_super, offset,
 					sizeof(struct f2fs_super_block));
 			ASSERT(ret >= 0);
@@ -2402,6 +2441,9 @@ static int check_sector_size(struct f2fs_super_block *sb)
 	set_sb(log_sectorsize, log_sectorsize);
 	set_sb(log_sectors_per_block, log_sectors_per_block);
 
+	if (get_sb(feature) & F2FS_FEATURE_SB_CHKSUM)
+		update_sb_chksum(sb);
+
 	memcpy(zero_buff + F2FS_SUPER_OFFSET, sb, sizeof(*sb));
 	DBG(1, "\tWriting super block, at offset 0x%08x\n", 0);
 	for (index = 0; index < 2; index++) {
@@ -2434,6 +2476,8 @@ static void tune_sb_features(struct f2fs_sb_info *sbi)
 	if (!sb_changed)
 		return;
 
+	if (get_sb(feature) & F2FS_FEATURE_SB_CHKSUM)
+		update_sb_chksum(sb);
 	write_superblock(sb);
 }
 
diff --git a/fsck/resize.c b/fsck/resize.c
index e9612b3..ca8c6f9 100644
--- a/fsck/resize.c
+++ b/fsck/resize.c
@@ -160,6 +160,9 @@ safe_resize:
 			(get_sb(segment_count_main) - 2));
 		return -1;
 	}
+	if (get_sb(feature) & F2FS_FEATURE_SB_CHKSUM)
+		update_sb_chksum(sb);
+
 	return 0;
 }
 
diff --git a/include/f2fs_fs.h b/include/f2fs_fs.h
index e279b9f..b6dfd29 100644
--- a/include/f2fs_fs.h
+++ b/include/f2fs_fs.h
@@ -279,6 +279,7 @@ static inline uint64_t bswap_64(uint64_t val)
 #define BITS_PER_BYTE		8
 #define F2FS_SUPER_MAGIC	0xF2F52010	/* F2FS Magic Number */
 #define CP_CHKSUM_OFFSET	4092
+#define SB_CHKSUM_OFFSET	3068
 #define MAX_PATH_LEN		64
 #define MAX_DEVICES		8
 
@@ -579,6 +580,7 @@ enum {
 #define F2FS_FEATURE_INODE_CRTIME	0x0100
 #define F2FS_FEATURE_LOST_FOUND		0x0200
 #define F2FS_FEATURE_VERITY		0x0400	/* reserved */
+#define F2FS_FEATURE_SB_CHKSUM		0x0800
 
 #define MAX_VOLUME_NAME		512
 
@@ -632,7 +634,8 @@ struct f2fs_super_block {
 	struct f2fs_device devs[MAX_DEVICES];	/* device list */
 	__le32 qf_ino[F2FS_MAX_QUOTAS];	/* quota inode numbers */
 	__u8 hot_ext_count;		/* # of hot file extension */
-	__u8 reserved[314];		/* valid reserved region */
+	__u8 reserved[310];		/* valid reserved region */
+	__le32 crc;			/* checksum of superblock */
 } __attribute__((packed));
 
 /*
@@ -1337,6 +1340,7 @@ struct feature feature_table[] = {					\
 	{ "inode_crtime",		F2FS_FEATURE_INODE_CRTIME },	\
 	{ "lost_found",			F2FS_FEATURE_LOST_FOUND },	\
 	{ "verity",			F2FS_FEATURE_VERITY },	/* reserved */ \
+	{ "sb_checksum",		F2FS_FEATURE_SB_CHKSUM },	\
 	{ NULL,				0x0},				\
 };
 
diff --git a/mkfs/f2fs_format.c b/mkfs/f2fs_format.c
index 621126c..012f3a8 100644
--- a/mkfs/f2fs_format.c
+++ b/mkfs/f2fs_format.c
@@ -187,6 +187,7 @@ static int f2fs_prepare_super_block(void)
 	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 crc;
 	enum quota_type qtype;
 	int i;
 
@@ -504,6 +505,14 @@ static int f2fs_prepare_super_block(void)
 
 	sb->feature = c.feature;
 
+	if (get_sb(feature) & F2FS_FEATURE_SB_CHKSUM) {
+		set_sb(checksum_offset, SB_CHKSUM_OFFSET);
+		/* calculate superblock checksum */
+		crc = f2fs_cal_crc32(F2FS_SUPER_MAGIC, sb, SB_CHKSUM_OFFSET);
+		set_sb(crc, crc);
+		MSG(0, "Info: set SB CRC successfully (0x%x)\n", crc);
+	}
+
 	return 0;
 }
 
-- 
2.18.0


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