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OpenCloudOS-Kernel/Documentation/filesystems/ext4/blockmap.rst

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ext4: import inode data fork chapter from wiki page Import the chapter about inode data fork from the on-disk format wiki page into the kernel documentation. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2018-07-30 03:45:00 +08:00
.. SPDX-License-Identifier: GPL-2.0
+---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| i.i\_block Offset | Where It Points |
+=====================+==============================================================================================================================================================================================================================+
| 0 to 11 | Direct map to file blocks 0 to 11. |
+---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 12 | Indirect block: (file blocks 12 to (``$block_size`` / 4) + 11, or 12 to 1035 if 4KiB blocks) |
| | |
| | +------------------------------+--------------------------------------------------------------------+ |
| | | Indirect Block Offset | Where It Points | |
| | +==============================+====================================================================+ |
| | | 0 to (``$block_size`` / 4) | Direct map to (``$block_size`` / 4) blocks (1024 if 4KiB blocks) | |
| | +------------------------------+--------------------------------------------------------------------+ |
+---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 13 | Double-indirect block: (file blocks ``$block_size``/4 + 12 to (``$block_size`` / 4) ^ 2 + (``$block_size`` / 4) + 11, or 1036 to 1049611 if 4KiB blocks) |
| | |
| | +--------------------------------+---------------------------------------------------------------------------------------------------------+ |
| | | Double Indirect Block Offset | Where It Points | |
| | +================================+=========================================================================================================+ |
| | | 0 to (``$block_size`` / 4) | Map to (``$block_size`` / 4) indirect blocks (1024 if 4KiB blocks) | |
| | | | | |
| | | | +------------------------------+--------------------------------------------------------------------+ | |
| | | | | Indirect Block Offset | Where It Points | | |
| | | | +==============================+====================================================================+ | |
| | | | | 0 to (``$block_size`` / 4) | Direct map to (``$block_size`` / 4) blocks (1024 if 4KiB blocks) | | |
| | | | +------------------------------+--------------------------------------------------------------------+ | |
| | +--------------------------------+---------------------------------------------------------------------------------------------------------+ |
+---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 14 | Triple-indirect block: (file blocks (``$block_size`` / 4) ^ 2 + (``$block_size`` / 4) + 12 to (``$block_size`` / 4) ^ 3 + (``$block_size`` / 4) ^ 2 + (``$block_size`` / 4) + 12, or 1049612 to 1074791436 if 4KiB blocks) |
| | |
| | +--------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------+ |
| | | Triple Indirect Block Offset | Where It Points | |
| | +================================+================================================================================================================================================+ |
| | | 0 to (``$block_size`` / 4) | Map to (``$block_size`` / 4) double indirect blocks (1024 if 4KiB blocks) | |
| | | | | |
| | | | +--------------------------------+---------------------------------------------------------------------------------------------------------+ | |
| | | | | Double Indirect Block Offset | Where It Points | | |
| | | | +================================+=========================================================================================================+ | |
| | | | | 0 to (``$block_size`` / 4) | Map to (``$block_size`` / 4) indirect blocks (1024 if 4KiB blocks) | | |
| | | | | | | | |
| | | | | | +------------------------------+--------------------------------------------------------------------+ | | |
| | | | | | | Indirect Block Offset | Where It Points | | | |
| | | | | | +==============================+====================================================================+ | | |
| | | | | | | 0 to (``$block_size`` / 4) | Direct map to (``$block_size`` / 4) blocks (1024 if 4KiB blocks) | | | |
| | | | | | +------------------------------+--------------------------------------------------------------------+ | | |
| | | | +--------------------------------+---------------------------------------------------------------------------------------------------------+ | |
| | +--------------------------------+------------------------------------------------------------------------------------------------------------------------------------------------+ |
+---------------------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+