Initial remote commit

misc_tools/test1.py

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+import struct
+
+CHUNK    = 128*512
+LV_START = 5120000*512
+BSIZE    = 4096
+IPG      = 8192
+INODE_SZ = 256
+
+def phys_from_virt(virt):
+    grp      = virt//(5*CHUNK)
+    in_group = virt%(5*CHUNK)
+    chunk_idx= in_group//CHUNK
+    intra    = in_group%CHUNK
+    if chunk_idx == 4: return None
+    return LV_START + grp*4*CHUNK + chunk_idx*CHUNK + intra
+
+def read_inode(inode_num):
+    group    = (inode_num-1)//IPG
+    idx      = (inode_num-1)%IPG
+    it_block = 1070 + group*512
+    virt     = it_block*BSIZE + idx*INODE_SZ
+    print(f'  inode {inode_num}: group={group} idx={idx}')
+    print(f'  inode table block: {it_block}')
+    print(f'  virtual byte: {virt}')
+    phys = phys_from_virt(virt)
+    print(f'  physical byte: {phys}')
+    if phys is None:
+        print(f'  IN METADATA CHUNK')
+        return None
+    with open('/dev/sda','rb') as f:
+        f.seek(phys)
+        return f.read(INODE_SZ)
+
+# Check known good inode - volumes directory
+print('=== Inode 1585918 (volumes dir) ===')
+data = read_inode(1585918)
+if data:
+    mode  = struct.unpack_from('<H', data,  0)[0]
+    size  = struct.unpack_from('<I', data,  4)[0]
+    links = struct.unpack_from('<H', data, 26)[0]
+    mtime = struct.unpack_from('<I', data, 16)[0]
+    ext_magic = struct.unpack_from('<H', data, 40)[0]
+    print(f'  mode=0x{mode:04x} size={size} links={links}')
+    print(f'  mtime={mtime} ext_magic=0x{ext_magic:04x}')
+    print(f'  valid dir: {(mode&0xf000)==0x4000 and ext_magic==0xf30a}')
+
+# Now check inode 2 via NBD (which applies translation correctly)
+print()
+print('=== Inode 2 via NBD device ===')
+group    = (2-1)//IPG
+idx      = (2-1)%IPG
+it_block = 1070 + group*512
+virt     = it_block*BSIZE + idx*INODE_SZ
+print(f'  virtual byte: {virt}')
+with open('/dev/nbd0','rb') as f:
+    f.seek(virt)
+    data = f.read(INODE_SZ)
+mode  = struct.unpack_from('<H', data,  0)[0]
+links = struct.unpack_from('<H', data, 26)[0]
+mtime = struct.unpack_from('<I', data, 16)[0]
+ext_magic = struct.unpack_from('<H', data, 40)[0]
+print(f'  mode=0x{mode:04x} links={links} mtime={mtime}')
+print(f'  ext_magic=0x{ext_magic:04x}')
+print(f'  first 32 bytes: {data[:32].hex()}')
+
+# Compare: what does debugfs think inode 2 contains?
+print()
+print('=== What istat says about inode 2 ===')
+import subprocess
+r = subprocess.run(['istat', '/dev/nbd0', '2'],
+                  capture_output=True, text=True)
+print(r.stdout[:500])
+print(r.stderr[:200])