On Wed 22-03-23 11:59:26, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> Currently if disk_scan_partitions() failed, GD_NEED_PART_SCAN will still
> set, and partition scan will be proceed again when blkdev_get_by_dev()
> is called. However, this will cause a problem that re-assemble partitioned
> raid device will creat partition for underlying disk.
>
> Test procedure:
>
> mdadm -CR /dev/md0 -l 1 -n 2 /dev/sda /dev/sdb -e 1.0
> sgdisk -n 0:0:+100MiB /dev/md0
> blockdev --rereadpt /dev/sda
> blockdev --rereadpt /dev/sdb
> mdadm -S /dev/md0
> mdadm -A /dev/md0 /dev/sda /dev/sdb
>
> Test result: underlying disk partition and raid partition can be
> observed at the same time
>
> Note that this can still happen in come corner cases that
> GD_NEED_PART_SCAN can be set for underlying disk while re-assemble raid
> device.
>
> Fixes: e5cfefa97bcc ("block: fix scan partition for exclusively open device again")
> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
This looks good to me. I've actually noticed this problem already when
looking at the patch resulting in commit e5cfefa97bcc but Jens merged it
before I got to checking it and then I've convinced myself it's not serious
enough to redo the patch. Anyway, feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> block/genhd.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/block/genhd.c b/block/genhd.c
> index 08bb1a9ec22c..a72e27d6779d 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -368,7 +368,6 @@ int disk_scan_partitions(struct gendisk *disk, fmode_t mode)
> if (disk->open_partitions)
> return -EBUSY;
>
> - set_bit(GD_NEED_PART_SCAN, &disk->state);
> /*
> * If the device is opened exclusively by current thread already, it's
> * safe to scan partitons, otherwise, use bd_prepare_to_claim() to
> @@ -381,12 +380,19 @@ int disk_scan_partitions(struct gendisk *disk, fmode_t mode)
> return ret;
> }
>
> + set_bit(GD_NEED_PART_SCAN, &disk->state);
> bdev = blkdev_get_by_dev(disk_devt(disk), mode & ~FMODE_EXCL, NULL);
> if (IS_ERR(bdev))
> ret = PTR_ERR(bdev);
> else
> blkdev_put(bdev, mode & ~FMODE_EXCL);
>
> + /*
> + * If blkdev_get_by_dev() failed early, GD_NEED_PART_SCAN is still set,
> + * and this will cause that re-assemble partitioned raid device will
> + * creat partition for underlying disk.
> + */
> + clear_bit(GD_NEED_PART_SCAN, &disk->state);
> if (!(mode & FMODE_EXCL))
> bd_abort_claiming(disk->part0, disk_scan_partitions);
> return ret;
> --
> 2.31.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
