Re: [PATCH V2] Add support for BTRFS raid5/6 to GRUB

[Daniel Kiper]

On Tue, Apr 24, 2018 at 09:13:09PM +0200, Goffredo Baroncelli wrote:
>
> Hi All,
>
> the aim of this patches set is to provide support for a BTRFS raid5/6
>  filesystem in GRUB.
>
> The first patch, implements the basic support for raid5/6. I.e this works when
>  all the disks
> are present.
>
> The next 4 patches, are preparatory ones.
>
> The last two implements the support for raid5/6 recovery. It allow to read
> from the filesystem even when 1 or 2 (for raid 6) disk(s) are missing.
>
> The last one is the more controversial. The code for the raid6 recovery is
> copied from the GRUB file reaid6_recovery.c . I preferred this approach,
> because the original code assumes that the read is GRUB_DISK_SECTOR_SIZE
> bytes based (512 bytes). Instead the GRUB BTRFS implementation need to
> read the disk with a granularity of the byte.
> I tried to update the code (and the function which the code calls), but
> the change was quite invasive. So for now I preferred to duplicating the
> code, to get some feedback.
>
> I tested the code in grub-emu, and it works (for me) both with all the disks,
>  and with some disks missing. I checked the sh1sums calculated from grub and
> from linux and these matched.
>
> Comments are welcome.

Mostly nitpicks. However, if we can reuse reaid6_recovery.c somehow that
will be great. Even if this require some more patches.

Daniel