imsm: confirm raid10 layout, fix up handling raid10 failures

1/ near-2 indeed matches how the Windows driver lays out the data
2/ update imsm_check_degraded to check for rebuilding disks in the
   raid10 case

Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/super-intel.c b/super-intel.c
index eb9a9e9f378cfd3b8e0e6d87cd67c05626c826f5..e9f90994386a978521dcce9845e6796abe938f64 100644 (file)
--- a/super-intel.c
+++ b/super-intel.c
@@ -678,7 +678,7 @@ static int imsm_level_to_layout(int level)
        case 6:
                return ALGORITHM_LEFT_ASYMMETRIC;
        case 10:
-               return 0x102; //FIXME is this correct?
+               return 0x102;
        }
        return -1;
 }
@@ -2310,30 +2310,35 @@ static __u8 imsm_check_degraded(struct intel_super *super, struct imsm_dev *dev,
        case 10:
        {
                /**
-                * check to see if any mirrors have failed,
-                * otherwise we are degraded
+                * check to see if any mirrors have failed, otherwise we
+                * are degraded.  Even numbered slots are mirrored on
+                * slot+1
                 */
-               int device_per_mirror = 2; /* FIXME is this always the case?
-                                           * and are they always adjacent?
-                                           */
-               int r10fail = 0;
                int i;
+               int insync;
 
                for (i = 0; i < map->num_members; i++) {
-                       int idx = get_imsm_disk_idx(dev, i);
-                       struct imsm_disk *disk = get_imsm_disk(super, idx);
+                       __u32 ord = get_imsm_ord_tbl_ent(dev, i);
+                       int idx = ord_to_idx(ord);
+                       struct imsm_disk *disk;
 
-                       if (!disk)
-                               r10fail++;
-                       else if (__le32_to_cpu(disk->status) & FAILED_DISK)
-                               r10fail++;
+                       /* reset the potential in-sync count on even-numbered
+                        * slots.  num_copies is always 2 for imsm raid10 
+                        */
+                       if ((i & 1) == 0)
+                               insync = 2;
 
-                       if (r10fail >= device_per_mirror)
-                               return IMSM_T_STATE_FAILED;
+                       disk = get_imsm_disk(super, idx);
+                       if (!disk ||
+                           __le32_to_cpu(disk->status) & FAILED_DISK ||
+                           ord & IMSM_ORD_REBUILD)
+                               insync--;
 
-                       /* reset 'r10fail' for next mirror set */
-                       if (!((i + 1) % device_per_mirror))
-                               r10fail = 0;
+                       /* no in-sync disks left in this mirror the
+                        * array has failed
+                        */
+                       if (insync == 0)
+                               return IMSM_T_STATE_FAILED;
                }
 
                return IMSM_T_STATE_DEGRADED;