[f2fs-dev] [PATCH] fsck: prevent working on devices with unsupported features

[Park Ju Hyung <qkrwngud825@gmail.com>]

fsck should never work on devices with unsupported features.

This is a real practical issue as fsck'ing a compressed image with
an older version of fsck destroys the entire image.

Non-rolling nature of popular distros such as Ubuntu is making the
situation worse.

Implement a long overdue safeguard to cope better with different
versions of f2fs-tools.

Signed-off-by: Park Ju Hyung <qkrwngud825@gmail.com>
---
 fsck/mount.c      |  9 +++++++++
 include/f2fs_fs.h | 18 +++++++++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/fsck/mount.c b/fsck/mount.c
index 6b2f17ebe8f3..107d61a88b7c 100644
--- a/fsck/mount.c
+++ b/fsck/mount.c
@@ -936,6 +936,7 @@ int sanity_check_raw_super(struct f2fs_super_block *sb, enum SB_ADDR sb_addr)
 int validate_super_block(struct f2fs_sb_info *sbi, enum SB_ADDR sb_addr)
 {
 	char buf[F2FS_BLKSIZE];
+	__le32 unsupported;
 
 	sbi->raw_super = malloc(sizeof(struct f2fs_super_block));
 	if (!sbi->raw_super)
@@ -975,6 +976,14 @@ int validate_super_block(struct f2fs_sb_info *sbi, enum SB_ADDR sb_addr)
 			c.fix_on = 1;
 		}
 		print_sb_state(sbi->raw_super);
+
+		/* check supported features */
+		unsupported = f2fs_get_unsupported_features(sbi->raw_super);
+		if (unsupported) {
+			MSG(0, "Error: Unsupported features: 0x%x\n", unsupported);
+			MSG(0, "Error: Please update your f2fs-tools\n");
+			return -EOPNOTSUPP;
+		}
 		return 0;
 	}
 
diff --git a/include/f2fs_fs.h b/include/f2fs_fs.h
index cdcce2cd3b85..433440af0458 100644
--- a/include/f2fs_fs.h
+++ b/include/f2fs_fs.h
@@ -683,6 +683,9 @@ enum {
 #define MAX_ACTIVE_NODE_LOGS	8
 #define MAX_ACTIVE_DATA_LOGS	8
 
+/*
+ * All features listed here should be appended to F2FS_SUPPORTED_FEATURES
+ */
 #define F2FS_FEATURE_ENCRYPT		0x0001
 #define F2FS_FEATURE_BLKZONED		0x0002
 #define F2FS_FEATURE_ATOMIC_WRITE	0x0004
@@ -696,7 +699,15 @@ 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
+
+/* Currently supported features by this version of f2fs-tools */
+#define F2FS_SUPPORTED_FEATURES \
+	(F2FS_FEATURE_ENCRYPT | F2FS_FEATURE_BLKZONED | F2FS_FEATURE_ATOMIC_WRITE | \
+	 F2FS_FEATURE_EXTRA_ATTR | F2FS_FEATURE_PRJQUOTA | F2FS_FEATURE_INODE_CHKSUM | \
+	 F2FS_FEATURE_FLEXIBLE_INLINE_XATTR | F2FS_FEATURE_QUOTA_INO | F2FS_FEATURE_INODE_CRTIME | \
+	 F2FS_FEATURE_LOST_FOUND | F2FS_FEATURE_VERITY | F2FS_FEATURE_SB_CHKSUM | \
+	 F2FS_FEATURE_CASEFOLD | F2FS_FEATURE_COMPRESSION)
 
 #define MAX_VOLUME_NAME		512
 
@@ -1600,6 +1611,11 @@ static inline int parse_feature(struct feature *table, const char *features)
 	return 0;
 }
 
+static inline __le32 f2fs_get_unsupported_features(struct f2fs_super_block *sb)
+{
+	return sb->feature & ~F2FS_SUPPORTED_FEATURES;
+}
+
 static inline int parse_root_owner(char *ids,
 			u_int32_t *root_uid, u_int32_t *root_gid)
 {
-- 
2.31.1



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