Re: [PATCH] md: forbid a RAID5 from having both a bitmap and a journal.

[NeilBrown <neilb@suse.com>]

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On Tue, Oct 17 2017, John Stoffel wrote:

>>>>>> "NeilBrown" == NeilBrown  <neilb@suse.com> writes:
>
> NeilBrown> Having both a bitmap and a journal is pointless.
> NeilBrown> Attempting to do so can corrupt the bitmap if the journal
> NeilBrown> replay happens before the bitmap is initialized.
> NeilBrown> Rather than try to avoid this corruption, simply
> NeilBrown> refuse to allow arrays with both a bitmap and a journal.
> NeilBrown> So:
> NeilBrown>  - if raid5_run sees both are present, fail.
>
> So what happens if there's someone out there with an array setup with
> both already?  Should the journal or the bitmap be removed at this
> time?  

If someone has an array like that they can assemble it with
  --update=no-bitmap

I'd rather not automatically disable things.

Thanks,
NeilBrown


>
> NeilBrown>  - if adding a bitmap finds a journal is present, fail
> NeilBrown>  - if adding a journal finds a bitmap is present, fail.
>
> NeilBrown> Cc: stable@vger.kernel.org (4.10+)
> NeilBrown> Signed-off-by: NeilBrown <neilb@suse.com>
> NeilBrown> ---
>
> NeilBrown> This patch should replace 8031c3ddc70ab, which should be reverted.
>
> NeilBrown> Thanks,
> NeilBrown> NeilBrown
>
>
> NeilBrown>  drivers/md/bitmap.c | 6 ++++++
> NeilBrown>  drivers/md/md.c     | 2 +-
> NeilBrown>  drivers/md/raid5.c  | 7 +++++++
> NeilBrown>  3 files changed, 14 insertions(+), 1 deletion(-)
>
> NeilBrown> diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
> NeilBrown> index cae57b5be817..f425905c97fa 100644
> NeilBrown> --- a/drivers/md/bitmap.c
> NeilBrown> +++ b/drivers/md/bitmap.c
> NeilBrown> @@ -1816,6 +1816,12 @@ struct bitmap *bitmap_create(struct mddev *mddev, int slot)
>  
> NeilBrown>  	BUG_ON(file && mddev->bitmap_info.offset);
>  
> NeilBrown> +	if (test_bit(MD_HAS_JOURNAL, &mddev->flags)) {
> NeilBrown> +		pr_notice("md/raid:%s: array with journal cannot have bitmap\n",
> NeilBrown> +			  mdname(mddev));
> NeilBrown> +		return ERR_PTR(-EBUSY);
> NeilBrown> +	}
> NeilBrown> +
> NeilBrown>  	bitmap = kzalloc(sizeof(*bitmap), GFP_KERNEL);
> NeilBrown>  	if (!bitmap)
> NeilBrown>  		return ERR_PTR(-ENOMEM);
> NeilBrown> diff --git a/drivers/md/md.c b/drivers/md/md.c
> NeilBrown> index 63ecfb063b76..bf06ff017eda 100644
> NeilBrown> --- a/drivers/md/md.c
> NeilBrown> +++ b/drivers/md/md.c
> NeilBrown> @@ -6384,7 +6384,7 @@ static int add_new_disk(struct mddev *mddev, mdu_disk_info_t *info)
> NeilBrown>  					break;
> NeilBrown>  				}
> NeilBrown>  			}
> NeilBrown> -			if (has_journal) {
> NeilBrown> +			if (has_journal || mddev->bitmap) {
> NeilBrown>  				export_rdev(rdev);
> NeilBrown>  				return -EBUSY;
> NeilBrown>  			}
> NeilBrown> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> NeilBrown> index 4f40ccd21cbb..e070e5c68801 100644
> NeilBrown> --- a/drivers/md/raid5.c
> NeilBrown> +++ b/drivers/md/raid5.c
> NeilBrown> @@ -7134,6 +7134,13 @@ static int raid5_run(struct mddev *mddev)
> NeilBrown>  			min_offset_diff = diff;
> NeilBrown>  	}
>  
> NeilBrown> +	if ((test_bit(MD_HAS_JOURNAL, &mddev->flags) || journal_dev) &&
> NeilBrown> +	    (mddev->bitmap_info.offset || mddev->bitmap_info.file)) {
> NeilBrown> +		pr_notice("md/raid:%s: array cannot have both journal and bitmap\n",
> NeilBrown> +			  mdname(mddev));
> NeilBrown> +		return -EINVAL;
> NeilBrown> +	}
> NeilBrown> +
> NeilBrown>  	if (mddev->reshape_position != MaxSector) {
> NeilBrown>  		/* Check that we can continue the reshape.
> NeilBrown>  		 * Difficulties arise if the stripe we would write to
> NeilBrown> -- 
> NeilBrown> 2.14.0.rc0.dirty
>
> NeilBrown> [DELETED ATTACHMENT signature.asc, application/pgp-signature]
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