> When I get to it I will try to play this game and let you guys know if
> it worked.
Thanks in advance. :-)
Meanwhile, with my limited knowledge about ext4, I am trying your
method. It seems it is working. But I am not sure about a few
things. Details below.
> If you know the estimated disk usage of the initial fs, say 1G:
> 1. mkfs a 1G ext4 fs with no journal, flex_bg=32, resize=4G
I did this: (hope you meant this)
dd if=/dev/zero of=a.img bs=4K count=256K
mkfs.ext4 -O ^has_journal,flex_bg -G 32 -E resize=4G a.img
> 2. mount it and cp -a /foo/* /mnt/
I did this:
sudo mount -t ext4 -o loop a.img /mnt/
cp -a /foo/* /mnt/
> 3. use new online resize to resize fs to 4G (maintaining flex_bg layout)
I did this: (hope you meant this)
e2fsck -f a.img
resize2fs a.img 4G
> 4. add journal to mounted fs (.journal file should be allocated with goal 0??)
I skipped this because I am not sure how to allocate .journal with goal 0.
> if my calculations are correct, the only blocks written beyond the 1G mark
> are the super block backup copies, so truncating the resulting image to 1G
> won't do any damage - even fsck shouldn't complain.
I did this:
sudo umount /mnt
truncate -s 1G a.img
e2fsck -f a.img
# this complains about several illegal blocks
# but after fixing, a.img mounts okay and files
# inside it looks okay.
Full operation log below:
--------------------------------------
--------------------------------------
--------------------------------------
$ dd if=/dev/zero of=a.img bs=4K count=256K
262144+0 records in
262144+0 records out
1073741824 bytes (1.1 GB) copied, 23.4067 s, 45.9 MB/s
$ mkfs.ext4 -O ^has_journal,flex_bg -G 32 -E resize=4G a.img
mke2fs 1.41.14 (22-Dec-2010)
a.img is not a block special device.
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
65536 inodes, 262144 blocks
13107 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=268435456
8 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376
Writing inode tables: done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 31 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
$ sudo mount -t ext4 -o loop a.img /mnt/
$ du -sh /usr/src/
92M /usr/src/
$ cp -a /usr/src/* /mnt/
$ e2fsck -f a.img
e2fsck 1.41.14 (22-Dec-2010)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
a.img: 11/65536 files (0.0% non-contiguous), 4443/262144 blocks
$ resize2fs a.img 4G
resize2fs 1.41.14 (22-Dec-2010)
Resizing the filesystem on a.img to 1048576 (4k) blocks.
The filesystem on a.img is now 1048576 blocks long.
$ sudo umount /mnt
$ truncate -s 1G a.img
$ e2fsck -f a.img
e2fsck 1.41.14 (22-Dec-2010)
Pass 1: Checking inodes, blocks, and sizes
Inode 7 has illegal block(s). Clear<y>? yes
Illegal block #2064 (294914) in inode 7. CLEARED.
Illegal block #2065 (819202) in inode 7. CLEARED.
Illegal block #2066 (884738) in inode 7. CLEARED.
Illegal block #3088 (294915) in inode 7. CLEARED.
Illegal block #3089 (819203) in inode 7. CLEARED.
Illegal block #3090 (884739) in inode 7. CLEARED.
Illegal block #4112 (294916) in inode 7. CLEARED.
Illegal block #4113 (819204) in inode 7. CLEARED.
Illegal block #4114 (884740) in inode 7. CLEARED.
Illegal block #5136 (294917) in inode 7. CLEARED.
Illegal block #5137 (819205) in inode 7. CLEARED.
Too many illegal blocks in inode 7.
Clear inode<y>? yes
Restarting e2fsck from the beginning...
Resize inode not valid. Recreate<y>? yes
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Free blocks count wrong for group #0 (24746, counted=24747).
Fix<y>? yes
Free blocks count wrong (234383, counted=234384).
Fix<y>? yes
a.img: ***** FILE SYSTEM WAS MODIFIED *****
a.img: 20864/65536 files (0.0% non-contiguous), 27760/262144 blocks
$ tune2fs -l a.img
tune2fs 1.41.14 (22-Dec-2010)
Filesystem volume name: <none>
Last mounted on: /mnt
Filesystem UUID: 56f4818f-ee66-4a30-a31c-917b0816f139
Filesystem magic number: 0xEF53
Filesystem revision #: 1 (dynamic)
Filesystem features: ext_attr resize_inode dir_index filetype extent flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags: signed_directory_hash
Default mount options: (none)
Filesystem state: clean
Errors behavior: Continue
Filesystem OS type: Linux
Inode count: 65536
Block count: 262144
Reserved block count: 13107
Free blocks: 234384
Free inodes: 44672
First block: 0
Block size: 4096
Fragment size: 4096
Reserved GDT blocks: 63
Blocks per group: 32768
Fragments per group: 32768
Inodes per group: 8192
Inode blocks per group: 512
Flex block group size: 32
Filesystem created: Sat Jul 30 03:18:44 2011
Last mount time: Sat Jul 30 03:19:04 2011
Last write time: Sat Jul 30 03:28:39 2011
Mount count: 0
Maximum mount count: 31
Last checked: Sat Jul 30 03:28:39 2011
Check interval: 15552000 (6 months)
Next check after: Thu Jan 26 03:28:39 2012
Lifetime writes: 722 kB
Reserved blocks uid: 0 (user root)
Reserved blocks gid: 0 (group root)
First inode: 11
Inode size: 256
Required extra isize: 28
Desired extra isize: 28
Default directory hash: half_md4
Directory Hash Seed: 6d50d9cc-e370-4868-acaa-92f7414df164
$ sudo mount -t ext4 -o loop a.img /mnt/
$ sudo du -sh /mnt/
92M /mnt/
$ cat /mnt/linux-headers-2.6.38-8/Documentation/Makefile
obj-m := DocBook/ accounting/ auxdisplay/ connector/ \
filesystems/ filesystems/configfs/ ia64/ laptops/ networking/ \
pcmcia/ spi/ timers/ vm/ watchdog/src/
$ ls -la /mnt/
total 32
drwxr-xr-x 5 round round 4096 Jul 30 03:26 .
drwxr-xr-x 23 root root 4096 Jul 9 01:24 ..
drwxr-xr-x 24 round round 4096 Apr 26 08:08 linux-headers-2.6.38-8
drwxr-xr-x 7 round round 4096 Apr 26 08:08 linux-headers-2.6.38-8-generic
drwx------ 2 root root 16384 Jul 30 03:18 lost+found
$ sudo umount /mnt
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