求助－ext4文件系统

不知道为什么／分区不能以ext4文件系统格式挂载。请高手帮忙！

Adding 891568k swap on /dev/sda6. Priority:-1 extents:1 across:891568k
EXT3 FS on sda1, internal journal
loop: module loaded
kjournald2 starting. Commit interval 5 seconds
EXT4 FS on sda8, internal journal
EXT4-fs: mounted filesystem with ordered data mode.
EXT4-fs: file extents enabled
kjournald2 starting. Commit interval 5 seconds
EXT4 FS on sda7, internal journal
EXT4-fs: mounted filesystem with ordered data mode.
EXT4-fs: file extents enabled
kjournald2 starting. Commit interval 5 seconds
EXT4 FS on sda9, internal journal
EXT4-fs: mounted filesystem with ordered data mode.
EXT4-fs: file extents enabled
kjournald2 starting. Commit interval 5 seconds
EXT4 FS on sda10, internal journal
EXT4-fs: mounted filesystem with ordered data mode.
EXT4-fs: file extents enabled
以上是挂载分区时的内容。下边是我的fstab。
# /etc/fstab: static file system information.
#
#
proc /proc proc defaults 0 0
/dev/sda1 / ext4dev defaults,errors=remount-ro 0 1
/dev/sda8 /home ext4dev defaults 0 2
/dev/sda7 /tmp ext4dev defaults 0 2
/dev/sda9 /usr ext4dev defaults 0 2
/dev/sda10 /var ext4dev defaults 0 2
/dev/sda6 none swap sw 0 0
/dev/hda /media/cdrom0 udf,iso9660 user,noauto 0 0
/dev/fd0 /media/floppy0 auto rw,user,noauto 0 0
/dev/sda5 /mnt reiserfs defaults 0 2