Signed-off-by: Goffredo Baroncelli <kreij...@inwind.it>
---
grub-core/fs/btrfs.c | 61 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 61 insertions(+)
diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
index be195448d..7e287d0ec 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 +766,65 @@ 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 in several stripes spread
+ * on the disks, following a layout like the one below
+ *
+ * Disk1 Disk2 Disk3 Ddisk4
+ *
+ * A1 B1 P1 Q1
+ * Q2 A2 B2 P2
+ * P3 Q3 A3 B3
+ * [...]
+ *
+ * Note that the placement of the parities depends by the row
+ * index;
+ * In the code below:
+ * stripe_nr -> is the stripe number not considering 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 column number (or number of disk)
+ * off -> logical address to read (from teh beginning of the
+ * chunk space)
+ * chunk_stripe_length -> size of a stripe (typically 64k)
+ * nstripes -> number of disks
+ *
+ */
+ stripe_nr = grub_divmod64 (off, chunk_stripe_length, &low);
+
+ high = grub_divmod64 (stripe_nr, nstripes - nparities, &stripen);
+
+ /*
+ * until now stripen is evaluated without the parities (0 for A1,
+ * A2, A3... 1 for B1, B2...); now consider also the parities (0
+ * for A1, 1 for A2, 2 for A3....); the math is done "modulo"
+ * number of disk
+ */
+ grub_divmod64 (high + stripen, nstripes, &stripen);
+
+ stripe_offset = low + chunk_stripe_length * high;
+ csize = chunk_stripe_length - low;
+
break;
}
default:
--
2.17.0
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