Initial remote commit

test/patch2.py

@@ -0,0 +1,38 @@
+import struct
+
+with open('/tmp/fs_meta.img', 'r+b') as f:
+    f.seek(1024)
+    sb = bytearray(f.read(1024))
+    
+    ro_compat = struct.unpack_from('<I', sb, 100)[0]
+    incompat  = struct.unpack_from('<I', sb,  96)[0]
+    compat    = struct.unpack_from('<I', sb,  92)[0]
+    
+    print(f'Before: compat=0x{compat:08x} incompat=0x{incompat:08x} ro_compat=0x{ro_compat:08x}')
+    
+    incompat  &= ~0x004   # clear HAS_JOURNAL
+    ro_compat &= ~0x400   # clear METADATA_CSUM
+    ro_compat &= ~0x010   # clear GDT_CSUM
+    compat    &= ~0x004   # clear HAS_JOURNAL from compat too
+    
+    # Zero the journal inode number so e2fsck ignores it
+    struct.pack_into('<I', sb, 180, 0)  # s_journal_inum = 0
+    
+    struct.pack_into('<I', sb,  92, compat)
+    struct.pack_into('<I', sb,  96, incompat)
+    struct.pack_into('<I', sb, 100, ro_compat)
+    struct.pack_into('<I', sb, 1020, 0)  # clear sb checksum
+    
+    f.seek(1024)
+    f.write(bytes(sb))
+    print(f'After:  compat=0x{compat:08x} incompat=0x{incompat:08x} ro_compat=0x{ro_compat:08x}')
+
+# Zero all GDT checksums
+with open('/tmp/fs_meta.img', 'r+b') as f:
+    f.seek(4096)
+    gdt = bytearray(f.read(35728 * 64))
+    for g in range(35728):
+        struct.pack_into('<H', gdt, g*64+30, 0)
+    f.seek(4096)
+    f.write(bytes(gdt))
+    print('GDT checksums zeroed')