Fix restarting of a reshaping array.

The last release broke the ability to assemble an array that
was in the middle of a reshape.
This patch adds code to test if the critical section needs
to be restored or not so that - if we have failed to restore it,
we know whether to fail or not.

diff --git a/Grow.c b/Grow.c
index 825747e71b31715c1b8b9f67f09d8da71f05e4a9..aec7c56e7a73cef2c095e07f9ef2739598711709 100644 (file)
--- a/Grow.c
+++ b/Grow.c
@@ -868,6 +868,8 @@ int Grow_restart(struct supertype *st, struct mdinfo *info, int *fdlist, int cnt
        int i, j;
        int old_disks;
        unsigned long long *offsets;
+       unsigned long long  nstripe, ostripe, last_block;
+       int ndata, odata;
 
        if (info->delta_disks < 0)
                return 1; /* cannot handle a shrink */
@@ -978,5 +980,24 @@ int Grow_restart(struct supertype *st, struct mdinfo *info, int *fdlist, int cnt
                /* And we are done! */
                return 0;
        }
+       /* Didn't find any backup data, try to see if any
+        * was needed.
+        */
+       nstripe = ostripe = 0;
+       odata = info->array.raid_disks - info->delta_disks - 1;
+       if (info->array.level == 6) odata--; /* number of data disks */
+       ndata = info->array.raid_disks - 1;
+       if (info->new_level == 6) ndata--;
+       last_block = 0;
+       while (nstripe >= ostripe) {
+               nstripe += info->new_chunk / 512;
+               last_block = nstripe * ndata;
+               ostripe = last_block / odata / (info->array.chunk_size/512) *
+                       (info->array.chunk_size/512);
+       }
+
+       if (info->reshape_progress >= last_block)
+               return 0;
+       /* needed to recover critical section! */
        return 1;
 }