Re: [PATCH 4/6] partitions: gpt: write inactive GPT first

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hi,

On 12/3/25 4:19 PM, Sascha Hauer wrote:
> There are two GPT partition tables on a device, the primary at the
> beginning of a device and the alternate at the end of the device.
> 
> For the sake of being more robust against power failures let's write the
> inactive GPT first and the currently active one afterwards. This always
> leaves us a usable GPT on the device when updating the partition table.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>


> ---
>  common/partitions/efi.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/common/partitions/efi.c b/common/partitions/efi.c
> index 8da62acf36646b62ff2fac25673adbc48650d299..1766f0123353d502065673d02e983e6cdd51b9af 100644
> --- a/common/partitions/efi.c
> +++ b/common/partitions/efi.c
> @@ -27,6 +27,8 @@ struct efi_partition_desc {
>  	gpt_header *gpt;
>  	gpt_entry *ptes;
>  	struct param_d *param_guid;
> +	bool good_pgpt;
> +	bool good_agpt;
>  };
>  
>  struct efi_partition {
> @@ -424,6 +426,9 @@ static int find_valid_gpt(struct efi_partition_desc *epd, void *buf)
>  	if (IS_ENABLED(CONFIG_PARTITION_DISK_EFI_GPT_COMPARE))
>  		compare_gpts(blk->dev, pgpt, agpt, lastlba);
>  
> +	epd->good_pgpt = good_pgpt;
> +	epd->good_agpt = good_agpt;
> +
>  	/* The good cases */
>  	if (good_pgpt) {
>  		epd->gpt  = pgpt;
> @@ -810,11 +815,11 @@ static __maybe_unused int efi_partition_write(struct partition_desc *pd)
>  	if (ret)
>  		return ret;
>  
> -	ret = __efi_partition_write(epd, true);
> +	ret = __efi_partition_write(epd, !epd->good_pgpt);
>  	if (ret)
>  		goto err_block_write;
>  
> -	ret = __efi_partition_write(epd, false);
> +	ret = __efi_partition_write(epd, epd->good_pgpt);
>  	if (ret)
>  		goto err_block_write;
>  
> 

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