On Thu, Aug 19, 2021 at 01:19:17AM +0300, Dmitry Osipenko wrote:
> Support looking up GPT at a non-standard location specified by a block
> device driver.
>
> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
> ---
> block/partitions/efi.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/block/partitions/efi.c b/block/partitions/efi.c
> index aaa3dc487cb5..7ca5c4c374d4 100644
> --- a/block/partitions/efi.c
> +++ b/block/partitions/efi.c
> @@ -585,6 +585,8 @@ static int find_valid_gpt(struct parsed_partitions *state, gpt_header **gpt,
> gpt_header *pgpt = NULL, *agpt = NULL;
> gpt_entry *pptes = NULL, *aptes = NULL;
> legacy_mbr *legacymbr;
> + struct gendisk *disk = state->disk;
> + const struct block_device_operations *fops = disk->fops;
> sector_t total_sectors = get_capacity(state->disk);
> u64 lastlba;
>
> @@ -619,6 +621,16 @@ static int find_valid_gpt(struct parsed_partitions *state, gpt_header **gpt,
> if (!good_agpt && force_gpt)
> good_agpt = is_gpt_valid(state, lastlba, &agpt, &aptes);
>
> + if (!good_agpt && force_gpt && fops->alternative_gpt_sector) {
> + sector_t agpt_sector;
> + int err;
> +
> + err = fops->alternative_gpt_sector(disk, &agpt_sector);
> + if (!err)
> + good_agpt = is_gpt_valid(state, agpt_sector,
> + &agpt, &aptes);
> + }
> +
When alternative_gpt_sector is provided I would expect it to override
the default, not be a fallback for it. But if someone tries to put
a broken (decoy, garbage) GPT at a standard place, current ordering
will prevent overriding it.
Best Regards
Michał Mirosław
