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btrfs: Add RAID 6 recovery for a btrfs filesystem 

Add the RAID 6 recovery, in order to use a RAID 6 filesystem even if some
disks (up to two) are missing. This code use the md RAID 6 code already
present in grub.

Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
This commit is contained in:
Goffredo Baroncelli 2018-10-22 19:29:39 +02:00 committed by Daniel Kiper
parent fa926cb4b4
commit 72e80c0255
1 changed files with 51 additions and 6 deletions
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57
grub-core/fs/btrfs.c
View File

@ -30,6 +30,7 @@
#include <grub/i18n.h>
#include <grub/btrfs.h>
#include <grub/crypto.h>
#include <grub/diskfilter.h>
GRUB_MOD_LICENSE ("GPLv3+");
@ -701,11 +702,36 @@ rebuild_raid5 (char *dest, struct raid56_buffer *buffers,
}
}
static grub_err_t
raid6_recover_read_buffer (void *data, int disk_nr,
grub_uint64_t addr __attribute__ ((unused)),
void *dest, grub_size_t size)
{
struct raid56_buffer *buffers = data;
if (!buffers[disk_nr].data_is_valid)
return grub_errno = GRUB_ERR_READ_ERROR;
grub_memcpy(dest, buffers[disk_nr].buf, size);
return grub_errno = GRUB_ERR_NONE;
}
static void
rebuild_raid6 (struct raid56_buffer *buffers, grub_uint64_t nstripes,
grub_uint64_t csize, grub_uint64_t parities_pos, void *dest,
grub_uint64_t stripen)
{
grub_raid6_recover_gen (buffers, nstripes, stripen, parities_pos,
dest, 0, csize, 0, raid6_recover_read_buffer);
}
static grub_err_t
raid56_read_retry (struct grub_btrfs_data *data,
struct grub_btrfs_chunk_item *chunk,
grub_uint64_t stripe_offset,
grub_uint64_t csize, void *buf)
grub_uint64_t stripe_offset, grub_uint64_t stripen,
grub_uint64_t csize, void *buf, grub_uint64_t parities_pos)
{
struct raid56_buffer *buffers;
grub_uint64_t nstripes = grub_le_to_cpu16 (chunk->nstripes);
@ -777,6 +803,14 @@ raid56_read_retry (struct grub_btrfs_data *data,
ret = GRUB_ERR_READ_ERROR;
goto cleanup;
}
else if (failed_devices > 2 && (chunk_type & GRUB_BTRFS_CHUNK_TYPE_RAID6))
{
grub_dprintf ("btrfs", "not enough disks for RAID 6: total %" PRIuGRUB_UINT64_T
", missing %" PRIuGRUB_UINT64_T "\n",
nstripes, failed_devices);
ret = GRUB_ERR_READ_ERROR;
goto cleanup;
}
else
grub_dprintf ("btrfs", "enough disks for RAID 5: total %"
PRIuGRUB_UINT64_T ", missing %" PRIuGRUB_UINT64_T "\n",
@ -786,7 +820,7 @@ raid56_read_retry (struct grub_btrfs_data *data,
if (chunk_type & GRUB_BTRFS_CHUNK_TYPE_RAID5)
rebuild_raid5 (buf, buffers, nstripes, csize);
else
grub_dprintf ("btrfs", "called rebuild_raid6(), NOT IMPLEMENTED\n");
rebuild_raid6 (buffers, nstripes, csize, parities_pos, buf, stripen);
ret = GRUB_ERR_NONE;
cleanup:
@ -876,9 +910,11 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
unsigned redundancy = 1;
unsigned i, j;
int is_raid56;
grub_uint64_t parities_pos = 0;
is_raid56 = !!(grub_le_to_cpu64 (chunk->type) &
GRUB_BTRFS_CHUNK_TYPE_RAID5);
is_raid56 = !!(grub_le_to_cpu64 (chunk->type) &
(GRUB_BTRFS_CHUNK_TYPE_RAID5 |
GRUB_BTRFS_CHUNK_TYPE_RAID6));
if (grub_le_to_cpu64 (chunk->size) <= off)
{
@ -1027,6 +1063,15 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
*/
grub_divmod64 (high + stripen, nstripes, &stripen);
/*
* parities_pos is equal to ((high - nparities) % nstripes)
* (see the diagram above). However, (high - nparities) can
* be negative, e.g. when high == 0, leading to an incorrect
* results. (high + nstripes - nparities) is always positive and
* modulo nstripes is equal to ((high - nparities) % nstripes).
*/
grub_divmod64 (high + nstripes - nparities, nstripes, &parities_pos);
stripe_offset = chunk_stripe_length * high + low;
csize = chunk_stripe_length - low;
@ -1067,7 +1112,7 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
grub_errno = GRUB_ERR_NONE;
if (err)
err = raid56_read_retry (data, chunk, stripe_offset,
csize, buf);
stripen, csize, buf, parities_pos);
}
else
for (i = 0; i < redundancy; i++)