md: export 'frozen' resync state through sysfs

The md resync engine has a 'frozen' state which ensures that
no resync/recovery.  This is used to avoid races.

Export this state through the 'sync_action' sysfs attribute
so that user-space can benefit and also avoid some races.

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

1 files changed, 9 insertions, 2 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 58e0b02a74c2..384e4f0904c8 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -3306,7 +3306,9 @@ static ssize_t
 action_show(mddev_t *mddev, char *page)
 {
         char *type = "idle";
-        if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+        if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
+                type = "frozen";
+        else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
             (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))) {
                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
                         type = "reshape";
@@ -3329,7 +3331,12 @@ action_store(mddev_t *mddev, const char *page, size_t len)
         if (!mddev->pers || !mddev->pers->sync_request)
                 return -EINVAL;
 
-        if (cmd_match(page, "idle")) {
+        if (cmd_match(page, "frozen"))
+                set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+        else
+                clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+
+        if (cmd_match(page, "idle") || cmd_match(page, "frozen")) {
                 if (mddev->sync_thread) {
                         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
                         md_unregister_thread(mddev->sync_thread);