xref: /OK3568_Linux_fs/kernel/Documentation/filesystems/ext4/blockmap.rst (revision 4882a59341e53eb6f0b4789bf948001014eff981)
1*4882a593Smuzhiyun.. SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun
3*4882a593Smuzhiyun+---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
4*4882a593Smuzhiyun| i.i\_block Offset   | Where It Points                                                                                                                                                                                                              |
5*4882a593Smuzhiyun+=====================+==============================================================================================================================================================================================================================+
6*4882a593Smuzhiyun| 0 to 11             | Direct map to file blocks 0 to 11.                                                                                                                                                                                           |
7*4882a593Smuzhiyun+---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
8*4882a593Smuzhiyun| 12                  | Indirect block: (file blocks 12 to (``$block_size`` / 4) + 11, or 12 to 1035 if 4KiB blocks)                                                                                                                                 |
9*4882a593Smuzhiyun|                     |                                                                                                                                                                                                                              |
10*4882a593Smuzhiyun|                     | +------------------------------+--------------------------------------------------------------------+                                                                                                                        |
11*4882a593Smuzhiyun|                     | | Indirect Block Offset        | Where It Points                                                    |                                                                                                                        |
12*4882a593Smuzhiyun|                     | +==============================+====================================================================+                                                                                                                        |
13*4882a593Smuzhiyun|                     | | 0 to (``$block_size`` / 4)   | Direct map to (``$block_size`` / 4) blocks (1024 if 4KiB blocks)   |                                                                                                                        |
14*4882a593Smuzhiyun|                     | +------------------------------+--------------------------------------------------------------------+                                                                                                                        |
15*4882a593Smuzhiyun+---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
16*4882a593Smuzhiyun| 13                  | Double-indirect block: (file blocks ``$block_size``/4 + 12 to (``$block_size`` / 4) ^ 2 + (``$block_size`` / 4) + 11, or 1036 to 1049611 if 4KiB blocks)                                                                     |
17*4882a593Smuzhiyun|                     |                                                                                                                                                                                                                              |
18*4882a593Smuzhiyun|                     | +--------------------------------+---------------------------------------------------------------------------------------------------------+                                                                                 |
19*4882a593Smuzhiyun|                     | | Double Indirect Block Offset   | Where It Points                                                                                         |                                                                                 |
20*4882a593Smuzhiyun|                     | +================================+=========================================================================================================+                                                                                 |
21*4882a593Smuzhiyun|                     | | 0 to (``$block_size`` / 4)     | Map to (``$block_size`` / 4) indirect blocks (1024 if 4KiB blocks)                                      |                                                                                 |
22*4882a593Smuzhiyun|                     | |                                |                                                                                                         |                                                                                 |
23*4882a593Smuzhiyun|                     | |                                | +------------------------------+--------------------------------------------------------------------+   |                                                                                 |
24*4882a593Smuzhiyun|                     | |                                | | Indirect Block Offset        | Where It Points                                                    |   |                                                                                 |
25*4882a593Smuzhiyun|                     | |                                | +==============================+====================================================================+   |                                                                                 |
26*4882a593Smuzhiyun|                     | |                                | | 0 to (``$block_size`` / 4)   | Direct map to (``$block_size`` / 4) blocks (1024 if 4KiB blocks)   |   |                                                                                 |
27*4882a593Smuzhiyun|                     | |                                | +------------------------------+--------------------------------------------------------------------+   |                                                                                 |
28*4882a593Smuzhiyun|                     | +--------------------------------+---------------------------------------------------------------------------------------------------------+                                                                                 |
29*4882a593Smuzhiyun+---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
30*4882a593Smuzhiyun| 14                  | Triple-indirect block: (file blocks (``$block_size`` / 4) ^ 2 + (``$block_size`` / 4) + 12 to (``$block_size`` / 4) ^ 3 + (``$block_size`` / 4) ^ 2 + (``$block_size`` / 4) + 12, or 1049612 to 1074791436 if 4KiB blocks)   |
31*4882a593Smuzhiyun|                     |                                                                                                                                                                                                                              |
32*4882a593Smuzhiyun|                     | +--------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------+                                          |
33*4882a593Smuzhiyun|                     | | Triple Indirect Block Offset   | Where It Points                                                                                                                                |                                          |
34*4882a593Smuzhiyun|                     | +================================+================================================================================================================================================+                                          |
35*4882a593Smuzhiyun|                     | | 0 to (``$block_size`` / 4)     | Map to (``$block_size`` / 4) double indirect blocks (1024 if 4KiB blocks)                                                                      |                                          |
36*4882a593Smuzhiyun|                     | |                                |                                                                                                                                                |                                          |
37*4882a593Smuzhiyun|                     | |                                | +--------------------------------+---------------------------------------------------------------------------------------------------------+   |                                          |
38*4882a593Smuzhiyun|                     | |                                | | Double Indirect Block Offset   | Where It Points                                                                                         |   |                                          |
39*4882a593Smuzhiyun|                     | |                                | +================================+=========================================================================================================+   |                                          |
40*4882a593Smuzhiyun|                     | |                                | | 0 to (``$block_size`` / 4)     | Map to (``$block_size`` / 4) indirect blocks (1024 if 4KiB blocks)                                      |   |                                          |
41*4882a593Smuzhiyun|                     | |                                | |                                |                                                                                                         |   |                                          |
42*4882a593Smuzhiyun|                     | |                                | |                                | +------------------------------+--------------------------------------------------------------------+   |   |                                          |
43*4882a593Smuzhiyun|                     | |                                | |                                | | Indirect Block Offset        | Where It Points                                                    |   |   |                                          |
44*4882a593Smuzhiyun|                     | |                                | |                                | +==============================+====================================================================+   |   |                                          |
45*4882a593Smuzhiyun|                     | |                                | |                                | | 0 to (``$block_size`` / 4)   | Direct map to (``$block_size`` / 4) blocks (1024 if 4KiB blocks)   |   |   |                                          |
46*4882a593Smuzhiyun|                     | |                                | |                                | +------------------------------+--------------------------------------------------------------------+   |   |                                          |
47*4882a593Smuzhiyun|                     | |                                | +--------------------------------+---------------------------------------------------------------------------------------------------------+   |                                          |
48*4882a593Smuzhiyun|                     | +--------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------+                                          |
49*4882a593Smuzhiyun+---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
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