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>
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1 changed files with 51 additions and 6 deletions
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@ -30,6 +30,7 @@
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#include <grub/i18n.h>
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#include <grub/btrfs.h>
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#include <grub/crypto.h>
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#include <grub/diskfilter.h>
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GRUB_MOD_LICENSE ("GPLv3+");
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@ -701,11 +702,36 @@ rebuild_raid5 (char *dest, struct raid56_buffer *buffers,
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}
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}
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static grub_err_t
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raid6_recover_read_buffer (void *data, int disk_nr,
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grub_uint64_t addr __attribute__ ((unused)),
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void *dest, grub_size_t size)
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{
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struct raid56_buffer *buffers = data;
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if (!buffers[disk_nr].data_is_valid)
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return grub_errno = GRUB_ERR_READ_ERROR;
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grub_memcpy(dest, buffers[disk_nr].buf, size);
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return grub_errno = GRUB_ERR_NONE;
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}
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static void
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rebuild_raid6 (struct raid56_buffer *buffers, grub_uint64_t nstripes,
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grub_uint64_t csize, grub_uint64_t parities_pos, void *dest,
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grub_uint64_t stripen)
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{
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grub_raid6_recover_gen (buffers, nstripes, stripen, parities_pos,
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dest, 0, csize, 0, raid6_recover_read_buffer);
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}
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static grub_err_t
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raid56_read_retry (struct grub_btrfs_data *data,
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struct grub_btrfs_chunk_item *chunk,
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grub_uint64_t stripe_offset,
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grub_uint64_t csize, void *buf)
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grub_uint64_t stripe_offset, grub_uint64_t stripen,
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grub_uint64_t csize, void *buf, grub_uint64_t parities_pos)
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{
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struct raid56_buffer *buffers;
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grub_uint64_t nstripes = grub_le_to_cpu16 (chunk->nstripes);
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@ -777,6 +803,14 @@ raid56_read_retry (struct grub_btrfs_data *data,
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ret = GRUB_ERR_READ_ERROR;
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goto cleanup;
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}
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else if (failed_devices > 2 && (chunk_type & GRUB_BTRFS_CHUNK_TYPE_RAID6))
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{
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grub_dprintf ("btrfs", "not enough disks for RAID 6: total %" PRIuGRUB_UINT64_T
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", missing %" PRIuGRUB_UINT64_T "\n",
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nstripes, failed_devices);
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ret = GRUB_ERR_READ_ERROR;
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goto cleanup;
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}
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else
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grub_dprintf ("btrfs", "enough disks for RAID 5: total %"
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PRIuGRUB_UINT64_T ", missing %" PRIuGRUB_UINT64_T "\n",
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@ -786,7 +820,7 @@ raid56_read_retry (struct grub_btrfs_data *data,
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if (chunk_type & GRUB_BTRFS_CHUNK_TYPE_RAID5)
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rebuild_raid5 (buf, buffers, nstripes, csize);
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else
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grub_dprintf ("btrfs", "called rebuild_raid6(), NOT IMPLEMENTED\n");
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rebuild_raid6 (buffers, nstripes, csize, parities_pos, buf, stripen);
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ret = GRUB_ERR_NONE;
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cleanup:
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@ -876,9 +910,11 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
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unsigned redundancy = 1;
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unsigned i, j;
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int is_raid56;
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grub_uint64_t parities_pos = 0;
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is_raid56 = !!(grub_le_to_cpu64 (chunk->type) &
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GRUB_BTRFS_CHUNK_TYPE_RAID5);
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is_raid56 = !!(grub_le_to_cpu64 (chunk->type) &
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(GRUB_BTRFS_CHUNK_TYPE_RAID5 |
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GRUB_BTRFS_CHUNK_TYPE_RAID6));
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if (grub_le_to_cpu64 (chunk->size) <= off)
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{
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@ -1027,6 +1063,15 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
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*/
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grub_divmod64 (high + stripen, nstripes, &stripen);
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/*
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* parities_pos is equal to ((high - nparities) % nstripes)
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* (see the diagram above). However, (high - nparities) can
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* be negative, e.g. when high == 0, leading to an incorrect
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* results. (high + nstripes - nparities) is always positive and
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* modulo nstripes is equal to ((high - nparities) % nstripes).
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*/
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grub_divmod64 (high + nstripes - nparities, nstripes, &parities_pos);
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stripe_offset = chunk_stripe_length * high + low;
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csize = chunk_stripe_length - low;
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@ -1067,7 +1112,7 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
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grub_errno = GRUB_ERR_NONE;
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if (err)
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err = raid56_read_retry (data, chunk, stripe_offset,
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csize, buf);
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stripen, csize, buf, parities_pos);
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}
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else
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for (i = 0; i < redundancy; i++)
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