[RFC][0/21]extend file size and filesystem size
- From: sho@xxxxxxxxxxxxxx
- Date: Thu, 13 Apr 2006 15:44:30 +0900
Hi all,
I have tried to extend the filesystem size and file size in ext2/3
until now. And this time, I merged all the previous patches.
Base kernel and command(e2fsprogs) were updated. As for functional
aspect, nothing changed particularly. But I added patches in relation
to ext2resize, including 2 bug fixes.
A summary of my reform to extend the specs in ext2/3 is as below.
- enlarge block size
Max block size in ext3 is restricted to 4KB by kernel, then I
modified to allow blocksize up to pagesize in checking blocksize
through mount.
- increase the number of blocks in filesystem
Max number of blocks is restricted to 2G-1 in ext2/3. This is
because the number of blocks is treated as unsigned 4byte
variable in kernel and command, and assembler instruction, which
can't treat >2G offset, is used on some commands. Then I made
up to 4G-1 blocks in filesystem usable by extending the
type of variables in relation to block and inode, and not using
assembler instruction which can't treat >2G offset.
- enlarge file size
Max file size in ext3 is about 2TB because i_blocks of ext3_inode
is 4byte variable by sector. And then, I extended the max file
size by changing the unit of ext3_inode.i_blocks from sector to
filesystem block.
Due to above reform, specs of the filesystem can be extended as below.
Max filesystem size:
Block size Original Extended
4KB 8TB 16TB
64KB 128TB 256TB
Max file size:
Block size Original Extended
4KB 1.998TB 4.003TB
64KB 1.998TB 256TB
This reform consists of the following 21 patches, but two of them
([17/21], [18/21]) are the fixes against the existing bugs in
ext2resize-1.1.19.
----------------------
Summary Of Patches
----------------------
The following is the patches for applying to linux-2.6.17-rc1 after
applying Mingming Cao's patch: "Extend ext3 filesystem limit from 8TB
to 16TB" linked from the following URL.
http://marc.theaimsgroup.com/?l=ext2-devel&m=114368281629281&w=2
[1/21] add percpu_llcounter for ext3
- The number of blocks and inodes are counted using
percpu_counter whose entry for counter is long type, so it
can only have less than 2G-1. Then I add percpu_llcounter
whose entry for counter is long long type in ext3.
[2/21] add percpu_llcounter for ext2
- Same fix as ext3 described above [1/21].
[3/21] modify format strings in print(ext3)
- The part which prints the signed value, related to a block
and an inode, in decimal is corrected so that it can print
unsigned one.
[4/21] modify format strings in print(ext2)
- Same fix as ext3 described above [3/21].
[5/21] modify format strings in print(bfs)
- As i_blocks of VFS inode gets 8 byte variable, change its
string format to %lld.
[6/21] modify format strings in print(efs)
- Same fix as bfs described above [5/21].
[7/21] modify format strings in print(jbd)
- Same fix as ext3 described above [3/21].
[8/21] change the type of variables manipulating a block or an
inode(ext3)
- Change the type of 4byte variables manipulating a block or
an inode from signed to unsigned.
- Where an overflow occurs in process of operation, casting
it to long long.
[9/21] change the type of variables manipulating a block or an
inode(ext2)
- Same fix as ext3 described above [8/21].
[10/21] enlarge block size(ext3)
- Add an incompat flag "EXT3_FEATURE_INCOMPAT_LARGE_BLOCK"
which indicates that the filesystem is extended.
- Allow block size till pagesize in ext3.
[11/21] extend file size(ext3)
- If the flag is set to super block, i_blocks of disk inode
(ext3_inode) is filesystem-block unit, and i_blocks of VFS
inode is sector unit.
- If the flag is set to super block, max file size is set to
(FS blocksize) * (2^32 -1).
[12/21] extend file size(ext2)
- Same fix as ext3 described above [11/21].
The following is the patches for applying to e2fsprogs-1.39-WIP-2006-04-09.
[13/21] modify format strings in print
- The part which prints the signed value, related to a block
and an inode, in decimal is corrected so that it can print
unsigned one.
[14/21] change the type of variables manipulating a block and an
inode
- Change the type of 4byte variables manipulating a block or
an inode from signed to unsigned.
- Where an overflow occurs in process of operation, casting
it to long long.
[15/21] change the type of variables which manipulate bitmap
- Change the type of 4byte variables manipulating bitmap
from signed to unsigned.
[16/21] enlarge file size and filesystem size
- Add an option "-O large_block" in mke2fs.
- With this option, the maximum size of a file is (blocksize)
* (2^32-1) bytes, and of a filesystem is (pagesize) *
(2^32-1).
The following is the patches for applying to ext2resize-1.1.19.
[17/21] fix the bug related to the option "resize_inode"
- A format of resize-inode in ext2prepare is different from
the one in mke2fs, so ext2prepare fails. Then I adapt
ext2prepare's to mke2fs's.
[18/21] fix the bug that an offset of an inode table is erroneously
calculated
- Running ext2resize results in failure due to an erroneous
offset of an inode table, then I fix how to calculate it.
[19/21] enlarge file size and filesystem size
- With "-O large_block" option in mke2fs, the maximum size of
a file is (blocksize) * (2^32-1) bytes, and of a filesystem
is (pagesize) * (2^32-1).
[20/21] change the type of variables manipulating a block or an inode
- Change the type of 4byte variables manipulating a block or
an inode from signed to unsigned.
- Where an overflow occurs in process of operation, casting
it to long long.
[21/21] modify format strings in print
- The part which prints the signed value, related to a block
and an inode, in decimal is corrected so that it can print
unsigned one.
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