On Fri, Jun 11, 2021 at 09:36:16PM +0200, Javier Martinez Canillas wrote:
> This incompat feature is used to denote that the filesystem stored its
> metadata checksum seed in the superblock. This is used to allow tune2fs
> to change the UUID on a mounted metadata_csum filesystem without having
> to rewrite all the disk metadata.
>
> But GRUB doesn't use the metadata checksum in anyway, so can just ignore
> this feature if is enabled. This is consistent with GRUB filesystem code
> in general which just does a best effort to access the filesystem's data.
>
> It may be removed from the ignored list in the future if supports to do
> metadata checksumming verification is added to the read-only FS driver.
Thanks,
you can add
Reviewed-by: Lukas Czerner <lczer...@redhat.com>
-Lukas
>
> Suggested-by: Eric Sandeen <esand...@redhat.com>
> Suggested-by: Lukas Czerner <lczer...@redhat.com>
> Signed-off-by: Javier Martinez Canillas <javi...@redhat.com>
> ---
>
> grub-core/fs/ext2.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/grub-core/fs/ext2.c b/grub-core/fs/ext2.c
> index 848bf939dba..238b2d76e38 100644
> --- a/grub-core/fs/ext2.c
> +++ b/grub-core/fs/ext2.c
> @@ -103,6 +103,7 @@ GRUB_MOD_LICENSE ("GPLv3+");
> #define EXT4_FEATURE_INCOMPAT_64BIT 0x0080
> #define EXT4_FEATURE_INCOMPAT_MMP 0x0100
> #define EXT4_FEATURE_INCOMPAT_FLEX_BG 0x0200
> +#define EXT4_FEATURE_INCOMPAT_CSUM_SEED 0x2000
> #define EXT4_FEATURE_INCOMPAT_ENCRYPT 0x10000
>
> /* The set of back-incompatible features this driver DOES support. Add (OR)
> @@ -123,9 +124,16 @@ GRUB_MOD_LICENSE ("GPLv3+");
> * mmp: Not really back-incompatible - was added as such to
> * avoid multiple read-write mounts. Safe to ignore for this
> * RO driver.
> + * checksum seed: Not really back-incompatible - was added to allow tools
> + * such as tune2fs to change the UUID on a mounted metadata
> + * checksummed filesystem. Safe to ignore for now since the
> + * driver doesn't support checksum verification. But it must
> + * be removed from this list if that support is added later.
> + *
> */
> #define EXT2_DRIVER_IGNORED_INCOMPAT ( EXT3_FEATURE_INCOMPAT_RECOVER \
> - | EXT4_FEATURE_INCOMPAT_MMP)
> + | EXT4_FEATURE_INCOMPAT_MMP \
> + | EXT4_FEATURE_INCOMPAT_CSUM_SEED)
>
>
> #define EXT3_JOURNAL_MAGIC_NUMBER 0xc03b3998U
> --
> 2.31.1
>
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