Grow: notice when --stop is synchronising a reshape and don't mess it up.

--stop now tries to wait for a reshape to be at just the right spot.
However for a reducing reshape, mdadm will be running in the
background watching, and might adjust sync_max and mess things up.

So teach "progress_reshape" to notice when "sync_max" is modified, and
leave it alone.

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

diff --git a/Grow.c b/Grow.c
index 20ecf3fd42895adb88dc9c4320f2147ee4f03ed2..7baa5f8af19e0d9f4757d3a431e99b525e5d8766 100644 (file)
--- a/Grow.c
+++ b/Grow.c
@@ -3526,7 +3526,7 @@ int progress_reshape(struct mdinfo *info, struct reshape *reshape,
                     unsigned long long backup_point,
                     unsigned long long wait_point,
                     unsigned long long *suspend_point,
-                    unsigned long long *reshape_completed)
+                    unsigned long long *reshape_completed, int *frozen)
 {
        /* This function is called repeatedly by the reshape manager.
         * It determines how much progress can safely be made and allows
@@ -3743,7 +3743,8 @@ int progress_reshape(struct mdinfo *info, struct reshape *reshape,
                wait_point = info->component_size - wait_point;
        }
 
-       sysfs_set_num(info, NULL, "sync_max", max_progress);
+       if (!*frozen)
+               sysfs_set_num(info, NULL, "sync_max", max_progress);
 
        /* Now wait.  If we have already reached the point that we were
         * asked to wait to, don't wait at all, else wait for any change.
@@ -3825,6 +3826,7 @@ check_progress:
                 */
                int wait = 10000;
                int rv = -2;
+               unsigned long long new_sync_max;
                while (fd >= 0 && rv < 0 && wait > 0) {
                        if (sysfs_wait(fd, &wait) != 1)
                                break;
@@ -3832,6 +3834,11 @@ check_progress:
                        case 0:
                                /* all good again */
                                rv = 1;
+                               /* If "sync_max" is no longer max_progress
+                                * we need to freeze things
+                                */
+                               sysfs_get_ll(info, NULL, "sync_max", &new_sync_max);
+                               *frozen = (new_sync_max != max_progress);
                                break;
                        case -2: /* read error - abort */
                                wait = 0;
@@ -4126,6 +4133,7 @@ int child_monitor(int afd, struct mdinfo *sra, struct reshape *reshape,
        struct mdinfo *sd;
        unsigned long stripes;
        int uuid[4];
+       int frozen = 0;
 
        /* set up the backup-super-block.  This requires the
         * uuid from the array.
@@ -4206,7 +4214,8 @@ int child_monitor(int afd, struct mdinfo *sra, struct reshape *reshape,
                reshape_completed = sra->reshape_progress;
                rv = progress_reshape(sra, reshape,
                                      backup_point, wait_point,
-                                     &suspend_point, &reshape_completed);
+                                     &suspend_point, &reshape_completed,
+                                     &frozen);
                /* external metadata would need to ping_monitor here */
                sra->reshape_progress = reshape_completed;