Re: [PATCH v2 4/9] util/grub-editenv: wire set_variables to optional fs_envblk

[Avnish Chouhan <avnish@linux.ibm.com>]

On 2025-09-15 14:39, grub-devel-request@gnu.org wrote:
> Message: 1
> Date: Mon, 15 Sep 2025 17:08:43 +0800
> From: Michael Chang <mchang@suse.com>
> To: The development of GNU GRUB <grub-devel@gnu.org>
> Cc: Neal Gompa <ngompa13@gmail.com>,	Marta Lewandowska
> 	<mlewando@redhat.com>
> Subject: [PATCH v2 4/9] util/grub-editenv: wire set_variables to
> 	optional fs_envblk
> Message-ID: <20250915090848.131937-5-mchang@suse.com>
> 
> This patch changes set_variables so that it can use an external
> environment block when one is present. The variable next_entry is
> written into the external block, env_block is treated as read only, and
> all other variables are written into the normal file based envblk.
> 
> A cleanup step is added to handle cases where GRUB at runtime writes
> variables into the external block because file based updates are not
> safe on a copy on write filesystem such as Btrfs. For example, the
> savedefault command can update saved_entry, and on Btrfs GRUB will 
> place
> that update in the external block instead of the file envblk. If an
> older copy remains in the external block, it would override the newer
> value from the file envblk when GRUB first loads the file and then
> applies the external block on top of it. To avoid this, whenever a
> variable is updated in the file envblk, any same named key in the
> external block is deleted.
> 
> Signed-off-by: Michael Chang <mchang@suse.com>
> ---
>  util/grub-editenv.c | 55 +++++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 53 insertions(+), 2 deletions(-)
> 
> diff --git a/util/grub-editenv.c b/util/grub-editenv.c
> index 26a81d2d0..d47adeb5e 100644
> --- a/util/grub-editenv.c
> +++ b/util/grub-editenv.c
> @@ -394,12 +394,33 @@ fs_envblk_write (grub_envblk_t envblk)
>    fclose (fp);
>  }
> 
> +struct var_lookup_ctx {
> +  const char *varname;
> +  bool found;
> +};
> +
> +static int
> +var_lookup_iter (const char *varname, const char *value __attribute__
> ((unused)), void *hook_data)
> +{
> +  struct var_lookup_ctx *ctx = (struct var_lookup_ctx *)hook_data;

Hi Michael,

Missing a space before "hook_data;"

Thank you!

Regards,
Avnish Chouhan

****

Reviewed-by: Avnish Chouhan <avnish@linux.ibm.com>


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