[Bug 1844012] [NEW] grub2 doesn't recognize ext4 with metadata_csum enabled

[Jim Bray]

Public bug reported:

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

grub-efi-amd64-bin:
  Installed: 2.02-2ubuntu8.13
  Candidate: 2.02-2ubuntu8.13

doesn't recognize an ext4 filesystem with metadata_csum set.

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

linux (hdx,gptx)/vm etc on an ext4 fs with metadata_csum enabled fails;
removing the metadata_csum option fixes this.

Oddly enough it doesn't fail with this error, from grub-core/fs/ext2.c:

grub_error (GRUB_ERR_BAD_FS, "filesystem has unsupported incompatible
features");

I will recreate the bug and get a precise error message and append 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`:
"metadata_csum
              This  ext4  feature  enables metadata checksumming.  This feature stores checksums for all of the filesystem metadata (superblock, group descriptor blocks, inode and block bitmaps, directories, and extent tree blocks).
              The checksum algorithm used for the metadata blocks is different than the one used for group descriptors with the uninit_bg feature.  These two features are incompatible and metadata_csum will  be  used  preferentially
              instead of uninit_bg."

** Affects: grub2 (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: ext4 grub metadata-csum

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https://bugs.launchpad.net/bugs/1844012

Title:
  grub2 doesn't recognize ext4 with metadata_csum enabled

Status in grub2 package in Ubuntu:
  New

Bug description:
  (probably)/usr/lib/grub/x86_64-efi/ext2.mod, from:

  grub-efi-amd64-bin:
    Installed: 2.02-2ubuntu8.13
    Candidate: 2.02-2ubuntu8.13

  doesn't recognize an ext4 filesystem with metadata_csum set.

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

  linux (hdx,gptx)/vm etc on an ext4 fs with metadata_csum enabled
  fails; removing the metadata_csum option fixes this.

  Oddly enough it doesn't fail with this error, from grub-
  core/fs/ext2.c:

  grub_error (GRUB_ERR_BAD_FS, "filesystem has unsupported incompatible
  features");

  I will recreate the bug and get a precise error message and append 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`:
  "metadata_csum
                This  ext4  feature  enables metadata checksumming.  This feature stores checksums for all of the filesystem metadata (superblock, group descriptor blocks, inode and block bitmaps, directories, and extent tree blocks).
                The checksum algorithm used for the metadata blocks is different than the one used for group descriptors with the uninit_bg feature.  These two features are incompatible and metadata_csum will  be  used  preferentially
                instead of uninit_bg."

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