Resize error when installing alongside

Same issue on Jammy - so not a new issue for kinetic. Sizing calculations seem to be mismatched (ISO vs storage) I presume.

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
https://iso.qa.ubuntu.com/qatracker/reports/bugs/1991083

From UbiquitySyslog.txt:

Sep 28 09:19:05 ubuntu-budgie ubiquity: /dev/sda3: 226050/1277952 files (0.1% non-contiguous), 2489274/5110784 blocks
Sep 28 09:19:05 ubuntu-budgie ubiquity: resize2fs 1.46.5 (30-Dec-2021)
Sep 28 09:19:05 ubuntu-budgie ubiquity: resize2fs
Sep 28 09:19:05 ubuntu-budgie ubiquity: :
Sep 28 09:19:05 ubuntu-budgie ubiquity: New size smaller than minimum (2582237)
Sep 28 09:19:05 ubuntu-budgie ubiquity:
Sep 28 09:19:05 ubuntu-budgie partman: Error resizing the ext2/ext3/ext4 file system
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: Reverting lockdown of the desktop environment.
Sep 28 09:19:09 ubuntu-budgie activate-dmraid: No Serial ATA RAID disks detected
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: switched to page partman
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: Traceback (most recent call last):
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: File "/usr/lib/ubiquity/ubiquity/misc.py", line 184, in grub_options
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: for disk in p.disks():
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: File "/usr/lib/ubiquity/ubiquity/parted_server.py", line 161, in disks
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: return sorted(os.listdir(devices))
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: FileNotFoundError: [Errno 2] No such file or directory: '/var/lib/partman/devices'
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]:
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: Traceback (most recent call last):
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: File "/usr/lib/ubiquity/ubiquity/misc.py", line 225, in boot_device
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: for disk in p.disks():
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: File "/usr/lib/ubiquity/ubiquity/parted_server.py", line 161, in disks
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: return sorted(os.listdir(devices))
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: FileNotFoundError: [Errno 2] No such file or directory: '/var/lib/partman/devices'
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]:
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: Traceback (most recent call last):
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: File "/usr/lib/ubiquity/ubiquity/misc.py", line 184, in grub_options
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: for disk in p.disks():
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: File "/usr/lib/ubiquity/ubiquity/parted_server.py", line 161, in disks
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: return sorted(os.listdir(devices))
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: FileNotFoundError: [Errno 2] No such file or directory: '/var/lib/partman/devices'
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]:
Sep 28 09:19:09 ubuntu-budgie ubiquity[5714]: switched to page partman
Sep 28 09:19:10 ubuntu-budgie partman: No matching physical volumes found

tl;dr: add a 10% margin to the current minimal size estimate

As far as I can tell, the issue originates in get_ext2_resize_range() in ubiquity/d-i/source/partman-partitioning/lib/resize.sh . The function parses the output from `tune2fs -l` in order to find the total number of blocks and the number of free blocks; it then uses the difference as the number of used blocks which gets multiplied by the block size to get the used space.

However, resize2fs disagrees. It also outputs the minimal number of blocks which is a fair bit higher than what had been computed by get_ext2_resize_range(). Resize2fs provides an estimate and it might be wrong but since obviously it is not going to accept anything lower than what is has determined, there is little point in not using its output value.

Unfortunately, resize2fs errors out immediately if the filesystem has not been unmounted cleanly (enough?). I don't know how ubiquity handles resizing of partition that need fsck first but in any case, I don't want to add code to run fsck before giving a size estimate.

Moreover, I don't think that it makes sense to use the absolute smallest size possible. The fact the user resizes the existing partition rather than overwriting it denotes a will to keep the other system working. If it gets shrunk so much that there is no free space, it's not going to be working well anymore. That can't be the user's intent.

I believe it is best to keep the current estimate but so something like multiplying it by 1.1 or even 1.05. The current estimate is quite off compared to what resize2fs outputs so it might need a bit of improvement too. I'll try to gather stats for various filesystems.

I haven't checked yet if that applied to anything else than ext* filesystems.

This bug was fixed in the package ubiquity - 22.10.9

---------------
ubiquity (22.10.9) kinetic; urgency=medium

  * partman/resize: add a margin to the minimal size for partition shrinking
    (LP: #1991083)

 -- Adrien Nader <email address hidden> Wed, 12 Oct 2022 10:14:27 +0000