bugGNU GRUB - Bugs: bug #56897, Boot fails for ext4 filesystems...


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bug #56897: Boot fails for ext4 filesystems with certain features enabled

Submitter:  tommy0910@gmail.com <tommy0910>
Submitted:  Sun 15 Sep 2019 07:35:13 AM UTC
Votes: 1
Category:  Booting Severity:  Major
Priority:  5 - Normal Item Group:  Software Error
Status:  None Privacy:  Public
Assigned to:  None Originator Name: 
Open/Closed:  Open Release:  2.02~beta1
Release:  Reproducibility:  Every Time
Planned Release:  None

Wed 19 Apr 2023 02:00:46 PM UTC, comment #3: 

This bug is about to become a much bigger problem. As of e2fsprogs 1.47.0, metadata_csum_seed is enabled by default.

You can see release notes here:

So default arguments mkfs.ext4 is now no longer compatible with GRUB ext4 detection.

Gentoo has backported this patch: https://git.savannah.gnu.org/cgit/grub.git/patch/?id=7fd5feff97c4b1f446f8fcf6d37aca0c64e7c763

As far as I can tell, that patch has not yet made it into a released GRUB version.

Anthony Ryan <anthonyryan1>
Mon 16 Sep 2019 10:56:22 PM UTC, comment #2: 

I built and installed grub 2.04. It still doesn't deal with metadata_csum_seed.

Jim Bray <jbray>
Mon 16 Sep 2019 10:24:18 PM UTC, comment #1: 

Details from report of this bug for metadata_csum_seed:


/usr/lib/grub/x86_64-efi/ext2.mod, from:

  Installed: 2.02-2ubuntu8.13
  Candidate: 2.02-2ubuntu8.13

doesn't recognize an ext4 filesystem with metadata_csum_seed set.

This is true in command-line grub, not just the update-grub software. Attempting

linux (hdx,gptx)/ etc

on an ext4 fs with metadata_csum enabled fails; removing the metadata_csum_seed option fixes this.

The failure is "unknown filesystem" for any ext4 fs with metadata_csum_seed set. Apparently saving the metadata checksum seed in the superblock changes it beyond recognition for grub.

 The message appears to be coming from
grub-2.04/grub-core/kern /fs.c:

grub_fs_probe (grub_device_t device)
 grub_error (GRUB_ERR_UNKNOWN_FS, N_("unknown filesystem"));
which appears to probe for filesystems by calling the fs modules to attempt to mount it.

I tried to install latest grub from eaon to see if upstream has fixed this, but it depended on too much other unreleased software such as libc6.

I pulled the 2.04 source. There is nothing in the Changelog that appears to address this.

from `man ext4`:
              This feature allows the filesystem to store the metadata checksum seed in the superblock, which allows the administrator to change the UUID of a filesystem using the metadata_csum feature while it is mounted.

Jim Bray <jbray>
Sun 15 Sep 2019 07:35:13 AM UTC, original submission:  

I observe that GRUB 2.04 fails to boot an ext4 filesystem which has one of the following features enabled:


My configuration is Arch linux, kernel 5.2, GRUB 2.04, ext2fsprogs 1.45.3

Steps to reproduce: install Arch from current 2019.08.01 release ISO; create new ext4 filesystem; enable one of the ext4 fs features mentioned (use common fs for both root and boot); configure grub to boot from this filesystem


error: unknown filesystem
Entering rescue mode...

tommy0910@gmail.com <tommy0910>


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  • -email is unavailable- added by tommy0910 (Submitted the item)

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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2019-09-16 jbray Carbon-Copy- Added jbray

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