md/raid5: change reshape-progress measurement to cope with reshaping backwards.
When reducing the number of devices in a raid4/5/6, the reshape
process has to start at the end of the array and work down to the
beginning. So we need to handle expand_progress and expand_lo
differently.
This patch renames "expand_progress" and "expand_lo" to avoid the
implication that anything is getting bigger (expand->reshape) and
every place they are used, we make sure that they are used the right
way depending on whether delta_disks is positive or negative.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index c2f37f2..b2edcc4 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -337,11 +337,16 @@
int raid_disks;
int max_nr_stripes;
- /* used during an expand */
- sector_t expand_progress; /* MaxSector when no expand happening */
- sector_t expand_lo; /* from here up to expand_progress it out-of-bounds
- * as we haven't flushed the metadata yet
- */
+ /* reshape_progress is the leading edge of a 'reshape'
+ * It has value MaxSector when no reshape is happening
+ * If delta_disks < 0, it is the last sector we started work on,
+ * else is it the next sector to work on.
+ */
+ sector_t reshape_progress;
+ /* reshape_safe is the trailing edge of a reshape. We know that
+ * before (or after) this address, all reshape has completed.
+ */
+ sector_t reshape_safe;
int previous_raid_disks;
struct list_head handle_list; /* stripes needing handling */