Re: [Patch v2 39/42] btrfs: reject raid5/6 fs for subpage

[Neal Gompa <ngompa13@gmail.com>]

On Tue, Apr 27, 2021 at 7:06 PM Qu Wenruo <wqu@suse.com> wrote:
>
> Raid5/6 is not only unsafe due to its write-hole problem, but also has
> tons of hardcoded PAGE_SIZE.
>
> So disable it for subpage support for now.
>
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> ---
>  fs/btrfs/disk-io.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index c9a3036c23bf..e6b941932a2b 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -3407,6 +3407,16 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
>                         goto fail_alloc;
>                 }
>         }
> +       if (sectorsize != PAGE_SIZE) {
> +               if (btrfs_super_incompat_flags(fs_info->super_copy) &
> +                       BTRFS_FEATURE_INCOMPAT_RAID56) {
> +                       btrfs_err(fs_info,
> +       "raid5/6 is not yet supported for sector size %u with page size %lu",
> +                               sectorsize, PAGE_SIZE);
> +                       err = -EINVAL;
> +                       goto fail_alloc;
> +               }
> +       }
>
>         ret = btrfs_init_workqueues(fs_info, fs_devices);
>         if (ret) {
> --
> 2.31.1
>

Couldn't this be restricted to ro-only safely?


-- 
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