介紹

losetup 是用來把 file mount 成 block device 的工具來,

我可應用在 mount dd 的 raw image

應用

查看有什麼東西在 mount 中:

# -a | --all

losetup -a

/dev/loop0: [fe02]:16465924 (/xen/domains/debian6/disk.img)
/dev/loop1: [fe02]:16465923 (/xen/domains/debian6/swap.img)
/dev/loop3: [fe00]:4554764 (/home/iso/CentOS-6.3-i386-minimal.iso)
/dev/loop4: [fe02]:16465926 (/xen/domains/centos6/centos6.img)

詳細資料

losetup [-l]

NAME       SIZELIMIT OFFSET AUTOCLEAR RO BACK-FILE                   DIO LOG-SEC
/dev/loop0         0      0         0  0 /home/recovery_disk/sde.img   0     512

AUTOCLEAR

--detach 後但 device 仍是 actively 就會 flag and destroyed later

找到下一個可用的 loop device:

# -f | --find

# --show               Display the name of the assigned loop device if the -f option

# -P, --partscan     Force the kernel to scan the partition table on a newly created loop  device.

losetup -f

/dev/loop2

建立 loop mount (image->block):

losetup  /dev/loop0  /root/hdd.img

detach device

# -d, --detach

losetup -d /dev/loop0

其他功能:

-r, --read-only

-j, --associated file              # show status of all loop devices associated with given file

Example

# loop device 放在中間 !!

losetup -r /dev/loop0 /mnt/vm/winxp/winxp-vio.raw

Kenerl modules

/etc/modules

loop

/etc/modprobe.conf

options loop max_loop=64

modprobe loop

所有 loop device 都是 major=7 的

loop0         b   7 0
loop1         b   7 1
loop2         b   7 2

建立: loop8

mknod -m 660 /dev/loop8 b 7 8

Mount Full HardDisk Image

一般而言, mount partition image 會比較容易

# mount partition image

losetup -r /dev/loop0 sdc2.img

# mount disk image

file winxp-vio.raw

winxp-vio.raw: x86 boot sector, Microsoft Windows XP MBR, Serial 0x2bc02bbf; partition 1: ID=0x7, active, 
starthead 1, startsector 63, 41942977 sectors, code offset 0xc0

file win7-data.raw

win7-data.raw: x86 boot sector

找出 partition 的 start 位置

parted winxp-vio.raw

# 把 display unit 改成 byte

unit b                          <-- byte

print

Number  Start   End           Size          Type     File system  Flags
 1      32256B  21474836479B  21474804224B  primary  ntfs         boot

# mount partition

losetup -r -o 32256 /dev/loop0 winxp-vio.raw

-r, --read-only

-o offset                           # offset = "Start byte"

# 測試是否成功 mount 起

blkid /dev/loop0

/dev/loop0: LABEL="winxp" UUID="187040E87040CDE6" TYPE="ntfs"