install: Force mkfs.xfs to overwrite

[sacsant]

Reusing a disk (after manually deleting partitions on it) with xfs
as file system, install to-disk command fails complaning about
existing file system on root partition.

Creating root filesystem (xfs) on device /dev/sdb2 (size=107.4 GB)

mkfs.xfs -m uuid=4826aa5b-0dd0-4382-a0c1-7c0b77cfd47d -L root /dev/sdb2
mkfs.xfs: /dev/sdb2 appears to contain an existing filesystem (xfs).
mkfs.xfs: Use the -f option to force overwrite.

Use the -f option with mkfs.xfs to force overwrite.

Signed-off-by: Sachin Sant sachinp@linux.ibm.com

[cgwalters]

Hm, you got this even when specifying --wipe? Or did you run wipefs manually?

[cgwalters]

(after manually deleting partitions on it)

Ah yes you did say that. Well...we have to-disk --wipe for this reason which note explicitly clears each child device too. (I don't know why wipefs doesn't have --recursive or so...probably wouldn't be hard to add)

How about: Only if --wipe is passed then we also pass -f to the mkfs invocations?

[sacsant]

Hm, you got this even when specifying --wipe? Or did you run wipefs manually?

Yes, the sequence I tried was as follows. I used bootc install to-disk command to write images to /dev/sdb which was successful. The partition table was as follows:

$ fdisk -l /dev/sdb
Disk /dev/sdb: 100 GiB, 107374182400 bytes, 26214400 sectors
..........
Disklabel type: gpt
Disk identifier: 647711E3-99C1-4591-95C6-EEDDD647BF2D

Device     Start      End  Sectors  Size Type
/dev/sdb1    256     1279     1024    4M PowerPC PReP boot
/dev/sdb2   1280 26214394 26213115  100G Linux filesystem
$

I then deleted the 2 partitions on /dev/sdb manually using disk command.

$ fdisk /dev/sdb

Welcome to fdisk (util-linux 2.40.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


Command (m for help): d
Partition number (1,2, default 2): 

Partition 2 has been deleted.

Command (m for help): d
Selected partition 1
Partition 1 has been deleted.

Command (m for help): p
Disk /dev/sdb: 100 GiB, 107374182400 bytes, 26214400 sectors
Disk model: VDASD           
Units: sectors of 1 * 4096 = 4096 bytes
Sector size (logical/physical): 4096 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 647711E3-99C1-4591-95C6-EEDDD647BF2D

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

After this when I ran the bootc install command it failed with the mentioned error. Even though --wipe was specified it only wiped the data on /dev/sdb.

Writing manifest to image destination
Installing image: docker://quay.io/sacsant/bootc:latest
Digest: sha256:9a52a5ed463a951331338f7dca7b9bcacf22fc14af64c62dfc0e63aeb21151d1
Wiping /dev/sdb
Wiping device /dev/sdb
/dev/sdb: 8 bytes were erased at offset 0x00001000 (gpt): 45 46 49 20 50 41 52 54
/dev/sdb: 8 bytes were erased at offset 0x18fffff000 (gpt): 45 46 49 20 50 41 52 54
/dev/sdb: 2 bytes were erased at offset 0x000001fe (PMBR): 55 aa
/dev/sdb: calling ioctl to re-read partition table: Success
Block setup: direct
       Size: 107374182400
     Serial: <unknown>
      Model: VDASD           
Initializing partitions
Reread partition table
Creating root filesystem (xfs) on device /dev/sdb2 (size=107.4 GB)
> mkfs.xfs -m uuid=23e201f4-8d49-4587-a0e9-cdd466aa3a0d -L root /dev/sdb2
mkfs.xfs: /dev/sdb2 appears to contain an existing filesystem (xfs).
mkfs.xfs: Use the -f option to force overwrite.
ERROR Installing to disk: Creating rootfs: Task Creating root filesystem (xfs) on device /dev/sdb2 (size=107.4 GB) failed: ExitStatus(unix_wait_status(256))

[cgwalters]

There's a flip side to this in that this "existing partitions" check is the only thing right now that stops one from actively destroying e.g. the booted disk if --wipe is used: we definitely need to strengthen the to-disk path to bail hard if the device is mounted for example, even if --wipe is specified.

(xref https://lwn.net/Articles/941764/ )

[cgwalters]

Great, thanks!

[cgwalters]

(This was missing a cargo fmt; in this repo remember to run make validate before pushing)

[sacsant]

(This was missing a cargo fmt; in this repo remember to run make validate before pushing)

Thanks. Will take care of this requirement for future PRs.