Grow: fix start_reshape for shrinking arrays.

When an array is being reshaped to fewer data devices the relationship
between sync_max and reshape_progress is different to when the number
of devices increases - we need to allow for that when setting
sync_max/sync_min.

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

diff --git a/Grow.c b/Grow.c
index 28f82b1092b926e0616f39353dfff9cd78ac3c57..cda780285cc99c63abd7016d84861ffac3cce163 100644 (file)
--- a/Grow.c
+++ b/Grow.c
@@ -698,7 +698,8 @@ static int subarray_set_num(char *container, struct mdinfo *sra, char *name, int
        return rc;
 }
 
-int start_reshape(struct mdinfo *sra, int already_running, int data_disks)
+int start_reshape(struct mdinfo *sra, int already_running,
+                 int before_data_disks, int data_disks)
 {
        int err;
        unsigned long long sync_max_to_set;
@@ -707,7 +708,11 @@ int start_reshape(struct mdinfo *sra, int already_running, int data_disks)
        err = sysfs_set_num(sra, NULL, "suspend_hi", sra->reshape_progress);
        err = err ?: sysfs_set_num(sra, NULL, "suspend_lo",
                                   sra->reshape_progress);
-       sync_max_to_set = sra->reshape_progress / data_disks;
+       if (before_data_disks <= data_disks)
+               sync_max_to_set = sra->reshape_progress / data_disks;
+       else
+               sync_max_to_set = (sra->component_size * data_disks
+                                  - sra->reshape_progress) / data_disks;
        if (!already_running)
                sysfs_set_num(sra, NULL, "sync_min", sync_max_to_set);
        err = err ?: sysfs_set_num(sra, NULL, "sync_max", sync_max_to_set);
@@ -2285,8 +2290,8 @@ started:
                }
        }
 
-       err = start_reshape(sra, restart,
-                           info->array.raid_disks - reshape.parity);
+       err = start_reshape(sra, restart, reshape.before.data_disks,
+                           reshape.after.data_disks);
        if (err) {
                fprintf(stderr, 
                        Name ": Cannot %s reshape for %s\n",