The code origins from "raid6_recovery.c". The code was changed because the
original one assumed that both the disk address and size are multiple of
GRUB_DISK_SECTOR_SIZE. This is not true for grub btrfs driver.
The code was made more generalized using a function pointer for reading
the data from the memory or disk.
Signed-off-by: Goffredo Baroncelli <kreij...@inwind.it>
---
grub-core/fs/btrfs.c | 211 +++++++++++++++++++++++++++++++++++++++++--
1 file changed, 204 insertions(+), 7 deletions(-)
diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
index 5c76a68f3..195313a31 100644
--- a/grub-core/fs/btrfs.c
+++ b/grub-core/fs/btrfs.c
@@ -30,6 +30,7 @@
#include <grub/i18n.h>
#include <grub/btrfs.h>
#include <grub/crypto.h>
+#include <grub/diskfilter.h>
GRUB_MOD_LICENSE ("GPLv3+");
@@ -695,19 +696,215 @@ rebuild_raid5 (struct raid56_buffer *buffers,
grub_uint64_t nstripes,
csize);
}
+
+/* copied from raid6_recover */
+/* x**y. */
+static grub_uint8_t powx[255 * 2];
+/* Such an s that x**s = y */
+static unsigned powx_inv[256];
+static const grub_uint8_t poly = 0x1d;
+
+static void
+grub_raid_block_mulx (unsigned mul, char *buf, grub_size_t size)
+{
+ grub_size_t i;
+ grub_uint8_t *p;
+
+ p = (grub_uint8_t *) buf;
+ for (i = 0; i < size; i++, p++)
+ if (*p)
+ *p = powx[mul + powx_inv[*p]];
+}
+
+static void
+grub_raid6_init_table (void)
+{
+ unsigned i;
+
+ grub_uint8_t cur = 1;
+ for (i = 0; i < 255; i++)
+ {
+ powx[i] = cur;
+ powx[i + 255] = cur;
+ powx_inv[cur] = i;
+ if (cur & 0x80)
+ cur = (cur << 1) ^ poly;
+ else
+ cur <<= 1;
+ }
+}
+
+static unsigned
+mod_255 (unsigned x)
+{
+ while (x > 0xff)
+ x = (x >> 8) + (x & 0xff);
+ if (x == 0xff)
+ return 0;
+ return x;
+}
+
+typedef grub_err_t (* raid_recover_read_t)(void *data, int disk_nr,
+ grub_uint64_t addr, void *dest,
+ grub_size_t size);
+#if 0
+/*
+ * code example to be used in raid6_recover.
+ */
+static grub_err_t
+raid_recover_read_diskfilter_array (void *data, int disk_nr,
+ grub_uint64_t sector,
+ void *buf, grub_size_t size)
+{
+ struct grub_diskfilter_segment *array = data;
+ return grub_diskfilter_read_node (&array->nodes[disk_nr],
+ (grub_disk_addr_t)sector,
+ size >> GRUB_DISK_SECTOR_BITS, buf);
+}
+#endif
+
+static grub_err_t
+raid_recover_read_raid56_buffer (void *data, int disk_nr, grub_uint64_t addr,
+ void *dest, grub_size_t size)
+{
+ struct raid56_buffer *buffers = data;
+
+ (void)addr;
+ grub_memcpy(dest, buffers[disk_nr].buf, size);
+
+ grub_errno = buffers[disk_nr].ok ? GRUB_ERR_NONE : GRUB_ERR_READ_ERROR;
+ return grub_errno;
+}
+
+static grub_err_t
+grub_raid6_recover (void *data, grub_uint64_t nstripes, int disknr, int p,
+ char *buf, grub_uint64_t sector, grub_size_t size,
+ raid_recover_read_t read_func, int layout)
+{
+ int i, q, pos;
+ int bad1 = -1, bad2 = -1;
+ char *pbuf = 0, *qbuf = 0;
+ static int table_initializated = 0;
+
+ if (!table_initializated)
+ {
+ grub_raid6_init_table();
+ table_initializated = 1;
+ }
+
+ pbuf = grub_zalloc (size);
+ if (!pbuf)
+ goto quit;
+
+ qbuf = grub_zalloc (size);
+ if (!qbuf)
+ goto quit;
+
+ q = p + 1;
+ if (q == (int) nstripes)
+ q = 0;
+
+ pos = q + 1;
+ if (pos == (int) nstripes)
+ pos = 0;
+
+ for (i = 0; i < (int) nstripes - 2; i++)
+ {
+ int c;
+ if (layout & GRUB_RAID_LAYOUT_MUL_FROM_POS)
+ c = pos;
+ else
+ c = i;
+ if (pos == disknr)
+ bad1 = c;
+ else
+ {
+ if (!read_func(data, pos, sector, buf, size))
+ {
+ grub_crypto_xor (pbuf, pbuf, buf, size);
+ grub_raid_block_mulx (c, buf, size);
+ grub_crypto_xor (qbuf, qbuf, buf, size);
+ }
+ else
+ {
+ /* Too many bad devices */
+ if (bad2 >= 0)
+ goto quit;
+
+ bad2 = c;
+ grub_errno = GRUB_ERR_NONE;
+ }
+ }
+
+ pos++;
+ if (pos == (int) nstripes)
+ pos = 0;
+ }
+
+ /* Invalid disknr or p */
+ if (bad1 < 0)
+ goto quit;
+
+ if (bad2 < 0)
+ {
+ /* One bad device */
+ if (!read_func(data, p, sector, buf, size))
+ {
+ grub_crypto_xor (buf, buf, pbuf, size);
+ goto quit;
+ }
+
+ grub_errno = GRUB_ERR_NONE;
+ if (read_func(data, q, sector, buf, size))
+ goto quit;
+
+ grub_crypto_xor (buf, buf, qbuf, size);
+ grub_raid_block_mulx (255 - bad1, buf,
+ size);
+ }
+ else
+ {
+ /* Two bad devices */
+ unsigned c;
+
+ if (read_func(data, p, sector, buf, size))
+ goto quit;
+
+ grub_crypto_xor (pbuf, pbuf, buf, size);
+
+ if (read_func(data, q, sector, buf, size))
+ goto quit;
+
+ grub_crypto_xor (qbuf, qbuf, buf, size);
+
+ c = mod_255((255 ^ bad1)
+ + (255 ^ powx_inv[(powx[bad2 + (bad1 ^ 255)] ^ 1)]));
+ grub_raid_block_mulx (c, qbuf, size);
+
+ c = mod_255((unsigned) bad2 + c);
+ grub_raid_block_mulx (c, pbuf, size);
+
+ grub_crypto_xor (pbuf, pbuf, qbuf, size);
+ grub_memcpy (buf, pbuf, size);
+ }
+
+quit:
+ grub_free (pbuf);
+ grub_free (qbuf);
+
+ return grub_errno;
+}
+
+/* end copy */
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)
{
- (void)buffers;
- (void)nstripes;
- (void)csize;
- (void)parities_pos;
- (void)dest;
- (void)stripen;
- grub_dprintf ("btrfs", "called rebuild_raid6(), NOT IMPLEMENTED\n");
+ grub_raid6_recover (buffers, nstripes, stripen, parities_pos,
+ dest, 0, csize,
+ raid_recover_read_raid56_buffer, 0);
}
static grub_err_t
--
2.17.0
_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/grub-devel
