[HaBo]

Debian Squeeze/Sid
Linux keksinat0r.is-a-geek.org 2.6.26-1-amd64 #1 SMP Fri Mar 13 17:46:45 UTC 2009 x86_64 GNU/Linux

$ modprobe ext4dev && lsmod | grep ext4dev
ext4dev               192944  0 
jbd2                   59440  1 ext4dev
crc16                   6528  1 ext4dev
mbcache                12804  3 ext4dev,ext3,ext2

$ mount -o loop ~/loop.ex4 /mnt/
mount: unknown filesystem type 'ext4'

$ mount -o loop -t ext4dev ~/loop.ex4 /mnt/
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

$ dmesg | tail
[ 5993.198466] EXT4-fs: loop0: not marked OK to use with test code.

$ fsck.ext4 loop.ex4 
e2fsck 1.41.3 (12-Oct-2008)
loop.ex4: clean, 71/2512 files, 1608/10000 blocks

$ fsck.ext4dev loop.ex4 
e2fsck 1.41.3 (12-Oct-2008)
loop.ex4: clean, 71/2512 files, 1608/10000 blocks

$dd if=/dev/zero of=test.ex4 bs=1024 count=100000 && mkfs.ext4 test.ex4
100000+0 records in
100000+0 records out
102400000 bytes (102 MB) copied, 0.682098 s, 150 MB/s
mke2fs 1.41.3 (12-Oct-2008)
test.ex4 is not a block special device.
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
25064 inodes, 100000 blocks
5000 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
13 block groups
8192 blocks per group, 8192 fragments per group
1928 inodes per group
Superblock backups stored on blocks: 
	8193, 24577, 40961, 57345, 73729

Writing inode tables: done                            
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 29 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

$mount -t ext4 -o loop test.ex4 /mnt/
mount: unknown filesystem type 'ext4'

$mount -t ext4dev -o loop test.ex4 /mnt/
mount: wrong fs type, bad option, bad superblock on /dev/loop1,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

$dmesg | tail
[10834.513233] EXT4-fs: loop1: not marked OK to use with test code.

$dd if=/dev/zero of=test.ex4dev bs=1024 count=100000 && mkfs.ext4dev test.ex4dev
100000+0 records in
100000+0 records out
102400000 bytes (102 MB) copied, 0.700535 s, 146 MB/s
mke2fs 1.41.3 (12-Oct-2008)
test.ex4dev is not a block special device.
Proceed anyway? (y,n) y
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
25064 inodes, 100000 blocks
5000 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
13 block groups
8192 blocks per group, 8192 fragments per group
1928 inodes per group
Superblock backups stored on blocks: 
	8193, 24577, 40961, 57345, 73729

Writing inode tables: done                            
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 21 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

$mount -t ext4dev -o loop test.extdev /mnt

$dmesg | tail
[10995.515694] kjournald2 starting.  Commit interval 5 seconds
[10995.516391] EXT4 FS on loop1, internal journal
[10995.516391] EXT4-fs: mounted filesystem with ordered data mode.
[10995.516391] EXT4-fs: file extents enabled
[10995.516391] EXT4-fs: mballoc enabled

mathias@workhorse:~$ dd if=/dev/zero of=disk.img bs=214748364 count=5
5+0 records in
5+0 records out
1073741820 bytes (1.1 GB) copied, 21.9048 s, 49.0 MB/s
mathias@workhorse:~$ su
Password: 
workhorse:/home/mathias# mkfs.ext4
mkfs.ext4     mkfs.ext4dev  
workhorse:/home/mathias# mkfs.ext4 disk.img 
mke2fs 1.41.3 (12-Oct-2008)
disk.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)
65536 inodes, 262143 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                            
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 25 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
workhorse:/home/mathias# mount -o loop disk.img /mnt
mount: unknown filesystem type 'ext4'
workhorse:/home/mathias# mount -t ext4 -o loop disk.img /mnt
mount: unknown filesystem type 'ext4'
workhorse:/home/mathias# mount -t ext4dev -o loop disk.img /mnt
mount: wrong fs type, bad option, bad superblock on /dev/loop0,
       missing codepage or helper program, or other error
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

workhorse:/home/mathias#

# dd if=/dev/zero of=/tmp/image bs=1M count=1k
# mkfs.ext4 /tmp/image
mke2fs 1.41.4 (27-Jan-2009)
/tmp/image ist kein spezielles Block-Gerät.
Trotzdem fortsetzen? (j,n) j
Dateisystem-Label=
OS-Typ: Linux
Blockgröße=4096 (log=2)
Fragmentgröße=4096 (log=2)
65536 Inodes, 262144 Blöcke
13107 Blöcke (5.00%) reserviert für den Superuser
Erster Datenblock=0
Maximale Dateisystem-Blöcke=268435456
8 Blockgruppen
32768 Blöcke pro Gruppe, 32768 Fragmente pro Gruppe
8192 Inodes pro Gruppe
Superblock-Sicherungskopien gespeichert in den Blöcken:
        32768, 98304, 163840, 229376

Schreibe Inode-Tabellen: erledigt
Erstelle Journal (8192 Blöcke): erledigt
Schreibe Superblöcke und Dateisystem-Accountinginformationen: erledigt

Das Dateisystem wird automatisch nach jeweils 29 Einhäng-Vorgängen bzw.
alle 180 Tage überprüft, je nachdem, was zuerst eintritt. Veränderbar mit
tune2fs -c oder -t .
# mount -o loop /tmp/image /mnt/mnt1
# mount | grep mnt1
/dev/loop1 on /mnt/mnt1 type ext4 (rw)

mathias@wizard:~$ uname -a
Linux wizard 2.6.26-1-amd64 #1 SMP Fri Mar 13 17:46:45 UTC 2009 x86_64 GNU/Linux
mathias@wizard:~$