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

[Goffredo Baroncelli]

On 04/23/2018 01:50 PM, Daniel Kiper wrote:
> On Tue, Apr 17, 2018 at 09:57:40PM +0200, Goffredo Baroncelli wrote:
>> Hi All,
>>
>> Below you can find a patch to add support for accessing files from
>> grub in a RAID5/6 btrfs filesystem. This is a RFC because it is
>> missing the support for recovery (i.e. if some devices are missed). In
>> the next days (weeks ?) I will extend this patch to support also this
>> case.
>>
>> Comments are welcome.
> 
> More or less LGTM. Just a nitpick below... I am happy to take full blown
> patch into GRUB if it is ready.

Thanks for the comments; however now I implemented also the recovery. It is 
under testing. Let me few days and I will resubmit the patches.

> 
>> BR
>> G.Baroncelli
>>
>>
>> ---
>>
>> commit 8c80a1b7c913faf50f95c5c76b4666ed17685666
>> Author: Goffredo Baroncelli <address@hidden>
>> Date:   Tue Apr 17 21:40:31 2018 +0200
>>
>>     Add initial support for btrfs raid5/6 chunk
>>
>> diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
>> index be195448d..4c5632acb 100644
>> --- a/grub-core/fs/btrfs.c
>> +++ b/grub-core/fs/btrfs.c
>> @@ -119,6 +119,8 @@ struct grub_btrfs_chunk_item
>>  #define GRUB_BTRFS_CHUNK_TYPE_RAID1         0x10
>>  #define GRUB_BTRFS_CHUNK_TYPE_DUPLICATED    0x20
>>  #define GRUB_BTRFS_CHUNK_TYPE_RAID10        0x40
>> +#define GRUB_BTRFS_CHUNK_TYPE_RAID5         0x80
>> +#define GRUB_BTRFS_CHUNK_TYPE_RAID6        0x100
>>    grub_uint8_t dummy2[0xc];
>>    grub_uint16_t nstripes;
>>    grub_uint16_t nsubstripes;
>> @@ -764,6 +766,39 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, 
>> grub_disk_addr_t addr,
>>            stripe_offset = low + chunk_stripe_length
>>              * high;
>>            csize = chunk_stripe_length - low;
>> +          break;
>> +        }
>> +      case GRUB_BTRFS_CHUNK_TYPE_RAID5:
>> +      case GRUB_BTRFS_CHUNK_TYPE_RAID6:
>> +        {
>> +          grub_uint64_t nparities;
>> +          grub_uint64_t parity_pos;
>> +          grub_uint64_t stripe_nr, high;
>> +          grub_uint64_t low;
>> +
>> +          redundancy = 1;   /* no redundancy for now */
>> +
>> +          if (grub_le_to_cpu64 (chunk->type) & GRUB_BTRFS_CHUNK_TYPE_RAID5)
>> +            {
>> +              grub_dprintf ("btrfs", "RAID5\n");
>> +              nparities = 1;
>> +            }
>> +          else
>> +            {
>> +              grub_dprintf ("btrfs", "RAID6\n");
>> +              nparities = 2;
>> +            }
>> +
>> +          stripe_nr = grub_divmod64 (off, chunk_stripe_length, &low);
>> +
>> +          high = grub_divmod64 (stripe_nr, nstripes - nparities, &stripen);
>> +          grub_divmod64 (high+nstripes-nparities, nstripes, &parity_pos);
>> +          grub_divmod64 (parity_pos+nparities+stripen, nstripes, &stripen);
> 
> Missing spaces around "+" and "-".
> 
> Daniel
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