fs/ntfs3: Add ability to format new mft records with bigger/smaller header

Just define in ntfs.h
	#define MFTRECORD_FIXUP_OFFSET  MFTRECORD_FIXUP_OFFSET_1
or
	#define MFTRECORD_FIXUP_OFFSET  MFTRECORD_FIXUP_OFFSET_3

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

Author: aalexandrovich

fs/ntfs3/ntfs.h

@@ -288,6 +288,15 @@ struct MFT_REC {
 
 #define MFTRECORD_FIXUP_OFFSET_1 offsetof(struct MFT_REC, res)
 #define MFTRECORD_FIXUP_OFFSET_3 offsetof(struct MFT_REC, fixups)
+/*
+ * define MFTRECORD_FIXUP_OFFSET as MFTRECORD_FIXUP_OFFSET_3 (0x30)
+ * to format new mft records with bigger header (as current ntfs.sys does)
+ *
+ * define MFTRECORD_FIXUP_OFFSET as MFTRECORD_FIXUP_OFFSET_1 (0x2A)
+ * to format new mft records with smaller header (as old ntfs.sys did)
+ * Both variants are valid.
+ */
+#define MFTRECORD_FIXUP_OFFSET  MFTRECORD_FIXUP_OFFSET_1
 
 static_assert(MFTRECORD_FIXUP_OFFSET_1 == 0x2A);
 static_assert(MFTRECORD_FIXUP_OFFSET_3 == 0x30);

fs/ntfs3/record.c

@@ -388,6 +388,8 @@ int mi_format_new(struct mft_inode *mi, struct ntfs_sb_info *sbi, CLST rno,
 
 	rec->seq = cpu_to_le16(seq);
 	rec->flags = RECORD_FLAG_IN_USE | flags;
+	if (MFTRECORD_FIXUP_OFFSET == MFTRECORD_FIXUP_OFFSET_3)
+		rec->mft_record = cpu_to_le32(rno);
 
 	mi->dirty = true;
 

fs/ntfs3/super.c

@@ -867,7 +867,7 @@ static int ntfs_init_from_boot(struct super_block *sb, u32 sector_size,
 	}
 
 	sbi->max_bytes_per_attr =
-		record_size - ALIGN(MFTRECORD_FIXUP_OFFSET_1, 8) -
+		record_size - ALIGN(MFTRECORD_FIXUP_OFFSET, 8) -
 		ALIGN(((record_size >> SECTOR_SHIFT) * sizeof(short)), 8) -
 		ALIGN(sizeof(enum ATTR_TYPE), 8);
 
@@ -909,10 +909,10 @@ static int ntfs_init_from_boot(struct super_block *sb, u32 sector_size,
 
 	sbi->new_rec = rec;
 	rec->rhdr.sign = NTFS_FILE_SIGNATURE;
-	rec->rhdr.fix_off = cpu_to_le16(MFTRECORD_FIXUP_OFFSET_1);
+	rec->rhdr.fix_off = cpu_to_le16(MFTRECORD_FIXUP_OFFSET);
 	fn = (sbi->record_size >> SECTOR_SHIFT) + 1;
 	rec->rhdr.fix_num = cpu_to_le16(fn);
-	ao = ALIGN(MFTRECORD_FIXUP_OFFSET_1 + sizeof(short) * fn, 8);
+	ao = ALIGN(MFTRECORD_FIXUP_OFFSET + sizeof(short) * fn, 8);
 	rec->attr_off = cpu_to_le16(ao);
 	rec->used = cpu_to_le32(ao + ALIGN(sizeof(enum ATTR_TYPE), 8));
 	rec->total = cpu_to_le32(sbi->record_size);