moosefs
[BUG] `mfsbdev` versus `losetup`: can't work with existing disk image
I can't manipulate existing disk image with mfsbdev due to bug(s). First, let's have a look at losetup where things work as expected (this is important for comparison and illustration of the problem):
# stat thinkpad_disk.raw
File: thinkpad__disk.raw
Size: 128035676160 Blocks: 250069680 IO Block: 65536 regular file
# losetup -v /dev/loop0 \
/mnt/mfs/HDD_RAW/thinkpad_disk.raw
# lsblk
loop0 7:0 0 119.2G 0 loop
# partprobe /dev/loop0 ## this is needed to read partitions of the disk image.
# lsblk
loop0 7:0 0 119.2G 0 loop
├─loop0p1 259:1 0 100M 0 part
└─loop0p2 259:2 0 119.1G 0 part
## Note: disk is ready to use.
## `ntfswipe -v -v --unused --pagefile /dev/loop0p2` works, etc.
# parted /dev/loop0
GNU Parted 3.5
Using /dev/loop0
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p
Model: Loopback device (loopback)
Disk /dev/loop0: 128GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:
Number Start End Size Type File system Flags
1 1049kB 106MB 105MB primary ntfs boot
2 106MB 128GB 128GB primary ntfs
###############################
# lsblk -b ## get disk and partitions' size in bytes.
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
loop0 7:0 0 128035676160 0 loop
├─loop0p1 259:1 0 104857600 0 part
└─loop0p2 259:2 0 127928369152 0 part
Now I'm trying to do the same using mfsbdev:
# modprobe -v nbd
insmod /lib/modules/6.12.9+bpo-rt-amd64/kernel/drivers/block/nbd.ko.xz
# mfsbdev start
mfsmaster accepted connection with parameters: read-write,restricted_ip,admin ; root mapped to root:root
# sudo mfsbdev map -f /HDD_RAW/thinkpad_disk.raw -n loop
## Note: absolute path did not work so `/mnt/mfs` had to be removed from the path.
# lsblk
nbd0 43:0 0 119.2G 0 disk
├─nbd0p1 43:1 0 800M 0 part
└─nbd0p2 43:2 0 118.5G 0 part
# Note: I didn't have to run `partprobe` to notify kernel of partitions. But if I do...
# (Note the problem: first partition should be `100M`, not `800M`.)
# partprobe /dev/nbd0
Error: Can't have a partition outside the disk!
# parted /dev/nbd0
GNU Parted 3.5
Using /dev/nbd0
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p
Error: Can't have a partition outside the disk!
Ignore/Cancel?
# lsblk -b
nbd0 43:0 0 128035676160 0 disk
├─nbd0p1 43:1 0 838860800 0 part
└─nbd0p2 43:2 0 127188426752 0 part
So mbsbdev got the size of the disk properly but somehow first partition is 800M instead of 100M and the second partition (i.e. end of the disk) is cropped, being smaller than it should be.
My guess is that the partition sizes in the image are stored in blocks, not in bytes and that losetup uses different block size (correct for this image) than mfsbdev (incorrect for this image). mfsbdev has an -b blocksize option to the map command. Play with it and see if it helps :)
