restripe: fix assignment of raid6 blocks for syndrome calculation.

Particularly for the _6 style.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/restripe.c b/restripe.c
index 3d4d1c61430ed8872c24b434c7d3dae654f59a47..f673206102f0aea0c2b449d6ceb067a4230f1e5d 100644 (file)
--- a/restripe.c
+++ b/restripe.c
@@ -482,22 +482,33 @@ int save_stripes(int *source, unsigned long long *offsets,
                        } else {
                                /* for md, q is over 'data_disks' blocks,
                                 * starting immediately after 'q'
+                                * Note that for the '_6' variety, the p block
+                                * makes a hole that we need to be careful of.
                                 */
-                               for (i = 0; i < data_disks; i++) {
-                                       int dnum = geo_map(i,
-                                                          start/chunk_size/data_disks,
-                                                          raid_disks, level, layout);
-                                       int snum;
+                               int j;
+                               int snum = 0;
+                               for (j = 0; j < raid_disks; j++) {
+                                       int dnum = (qdisk + 1 + j) % raid_disks;
+                                       if (dnum == disk || dnum == qdisk)
+                                               continue;
+                                       for (i = 0; i < data_disks; i++)
+                                               if (geo_map(i,
+                                                           start/chunk_size/data_disks,
+                                                           raid_disks, level, layout) == dnum)
+                                                       break;
                                        /* i is the logical block number, so is index to 'buf'.
                                         * dnum is physical disk number
                                         * snum is syndrome disk for which 0 is immediately after Q
                                         */
-                                       snum = (raid_disks + dnum - qdisk - 1) % raid_disks;
                                        bufs[snum] = (uint8_t*)buf + chunk_size * i;
+
+                                       if (fblock[0] == i)
+                                               fdisk[0] = snum;
+                                       if (fblock[1] == i)
+                                               fdisk[1] = snum;
+                                       snum++;
                                }
 
-                               fdisk[0] = (raid_disks + fdisk[0] - qdisk - 1) % raid_disks;
-                               fdisk[1] = (raid_disks + fdisk[1] - qdisk - 1) % raid_disks;
                                syndrome_disks = data_disks;
                        }