md/raid5: allow for change in data_offset while managing a reshape.
The important issue here is incorporating the different in data_offset
into calculations concerning when we might need to over-write data
that is still thought to be valid.
To this end we find the minimum offset difference across all devices
and add that where appropriate.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 8d8e139..c6bdfa0 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -385,6 +385,12 @@
short generation; /* increments with every reshape */
unsigned long reshape_checkpoint; /* Time we last updated
* metadata */
+ long long min_offset_diff; /* minimum difference between
+ * data_offset and
+ * new_data_offset across all
+ * devices. May be negative,
+ * but is closest to zero.
+ */
struct list_head handle_list; /* stripes needing handling */
struct list_head hold_list; /* preread ready stripes */
