From: Goffredo Baroncelli <kreij...@inwind.it> Signed-off-by: Goffredo Baroncelli <kreij...@inwind.it> --- grub-core/fs/btrfs.c | 74 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+)
diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c index be195448d..9bc6d399d 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 +766,78 @@ 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, stripe_nr, high, 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; + } + + /* + * A RAID 6 layout consists of several stripes spread on the + * disks, following a layout like the one below + * + * Disk0 Disk1 Disk2 Disk3 + * + * A1 B1 P1 Q1 + * Q2 A2 B2 P2 + * P3 Q3 A3 B3 + * [...] + * + * Note that the placement of the parities depends on row index. + * Pay attention that the BTRFS terminolgy may be different + * from others RAID implementation (e.g. lvm/dm or md). In BTRFS + * a contiguous block of data of a disk (like A1) is called + * stripe. + * In the code below: + * - stripe_nr is the stripe number without the parities + * (A1 = 0, B1 = 1, A2 = 2, B2 = 3, ...), + * - high is the row number (0 for A1...Q1, 1 for Q2...P2, ...), + * - stripen is the disk number in a row (0 for A1,Q2,P3, 1 for + * B1...), + * - off is the logical address to read, + * - chunk_stripe_length is the size of a stripe (typically 64k), + * - nstripes is the number of disks of a row + * - low is the offset of the data inside a stripe, + * - stripe_offset is the data offset in an array, + * - csize is the "potential" data to read. It will be reduced to + * size if the latter is smaller. + * - nparities is the number of parities (1 for RAID5, 2 for + * RAID6); used only in RAID5/6 code. + */ + stripe_nr = grub_divmod64 (off, chunk_stripe_length, &low); + + /* + * stripen is computed without the parities (0 for A1, A2, A3... + * 1 for B1, B2...). + */ + high = grub_divmod64 (stripe_nr, nstripes - nparities, &stripen); + + /* + * the stripes are spread across the disks, each row their + * position is shifted by 1 place. So to compute the real disk + * number occuped by a stripe, we need to sum also the + * "row number" in modulo nstripes (0 for A1, 1 for A2, 2 for + * A3....). + */ + grub_divmod64 (high + stripen, nstripes, &stripen); + + stripe_offset = low + chunk_stripe_length * high; + csize = chunk_stripe_length - low; + break; } default: -- 2.19.0 _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel