Documentation/filesystems/ext4/ondisk/blockmap.rst

   1 .. SPDX-License-Identifier: GPL-2.0
   2
   3 +---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   4 | i.i\_block Offset   | Where It Points                                                                                                                                                                                                              |
   5 +=====================+==============================================================================================================================================================================================================================+
   6 | 0 to 11             | Direct map to file blocks 0 to 11.                                                                                                                                                                                           |
   7 +---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
   8 | 12                  | Indirect block: (file blocks 12 to (``$block_size`` / 4) + 11, or 12 to 1035 if 4KiB blocks)                                                                                                                                 |
   9 |                     |                                                                                                                                                                                                                              |
  10 |                     | +------------------------------+--------------------------------------------------------------------+                                                                                                                        |
  11 |                     | | Indirect Block Offset        | Where It Points                                                    |                                                                                                                        |
  12 |                     | +==============================+====================================================================+                                                                                                                        |
  13 |                     | | 0 to (``$block_size`` / 4)   | Direct map to (``$block_size`` / 4) blocks (1024 if 4KiB blocks)   |                                                                                                                        |
  14 |                     | +------------------------------+--------------------------------------------------------------------+                                                                                                                        |
  15 +---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
  16 | 13                  | Double-indirect block: (file blocks ``$block_size``/4 + 12 to (``$block_size`` / 4) ^ 2 + (``$block_size`` / 4) + 11, or 1036 to 1049611 if 4KiB blocks)                                                                     |
  17 |                     |                                                                                                                                                                                                                              |
  18 |                     | +--------------------------------+---------------------------------------------------------------------------------------------------------+                                                                                 |
  19 |                     | | Double Indirect Block Offset   | Where It Points                                                                                         |                                                                                 |
  20 |                     | +================================+=========================================================================================================+                                                                                 |
  21 |                     | | 0 to (``$block_size`` / 4)     | Map to (``$block_size`` / 4) indirect blocks (1024 if 4KiB blocks)                                      |                                                                                 |
  22 |                     | |                                |                                                                                                         |                                                                                 |
  23 |                     | |                                | +------------------------------+--------------------------------------------------------------------+   |                                                                                 |
  24 |                     | |                                | | Indirect Block Offset        | Where It Points                                                    |   |                                                                                 |
  25 |                     | |                                | +==============================+====================================================================+   |                                                                                 |
  26 |                     | |                                | | 0 to (``$block_size`` / 4)   | Direct map to (``$block_size`` / 4) blocks (1024 if 4KiB blocks)   |   |                                                                                 |
  27 |                     | |                                | +------------------------------+--------------------------------------------------------------------+   |                                                                                 |
  28 |                     | +--------------------------------+---------------------------------------------------------------------------------------------------------+                                                                                 |
  29 +---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
  30 | 14                  | Triple-indirect block: (file blocks (``$block_size`` / 4) ^ 2 + (``$block_size`` / 4) + 12 to (``$block_size`` / 4) ^ 3 + (``$block_size`` / 4) ^ 2 + (``$block_size`` / 4) + 12, or 1049612 to 1074791436 if 4KiB blocks)   |
  31 |                     |                                                                                                                                                                                                                              |
  32 |                     | +--------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------+                                          |
  33 |                     | | Triple Indirect Block Offset   | Where It Points                                                                                                                                |                                          |
  34 |                     | +================================+================================================================================================================================================+                                          |
  35 |                     | | 0 to (``$block_size`` / 4)     | Map to (``$block_size`` / 4) double indirect blocks (1024 if 4KiB blocks)                                                                      |                                          |
  36 |                     | |                                |                                                                                                                                                |                                          |
  37 |                     | |                                | +--------------------------------+---------------------------------------------------------------------------------------------------------+   |                                          |
  38 |                     | |                                | | Double Indirect Block Offset   | Where It Points                                                                                         |   |                                          |
  39 |                     | |                                | +================================+=========================================================================================================+   |                                          |
  40 |                     | |                                | | 0 to (``$block_size`` / 4)     | Map to (``$block_size`` / 4) indirect blocks (1024 if 4KiB blocks)                                      |   |                                          |
  41 |                     | |                                | |                                |                                                                                                         |   |                                          |
  42 |                     | |                                | |                                | +------------------------------+--------------------------------------------------------------------+   |   |                                          |
  43 |                     | |                                | |                                | | Indirect Block Offset        | Where It Points                                                    |   |   |                                          |
  44 |                     | |                                | |                                | +==============================+====================================================================+   |   |                                          |
  45 |                     | |                                | |                                | | 0 to (``$block_size`` / 4)   | Direct map to (``$block_size`` / 4) blocks (1024 if 4KiB blocks)   |   |   |                                          |
  46 |                     | |                                | |                                | +------------------------------+--------------------------------------------------------------------+   |   |                                          |
  47 |                     | |                                | +--------------------------------+---------------------------------------------------------------------------------------------------------+   |                                          |
  48 |                     | +--------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------+                                          |
  49 +---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+