[PATCH]: Mirror: warn when activating mirror and !ignore_lvm_mirrors

[Jonathan Brassow <jbrassow@redhat.com>]

Not sure if I care for the static variable, but I don't want it printed
for every mirror on every command that activates...

 brassow


Mirror: Print warning on activation if mirrors exists and !ignore_lvm_mirrors

Print a warning if mirrors are present and config file settings indicate
that they can be scanned for labels.  (A process that has the potential
to block indefinitely if it happens just after a failure.)

Index: lvm2/lib/activate/activate.c
===================================================================
--- lvm2.orig/lib/activate/activate.c
+++ lvm2/lib/activate/activate.c
@@ -1077,9 +1077,18 @@ static int _lv_open_count(struct cmd_con
 
 static int _lv_activate_lv(struct logical_volume *lv, struct lv_activate_opts *laopts)
 {
+	static int mirror_warning_printed = 0;
 	int r;
 	struct dev_manager *dm;
 
+	if (lv_is_mirrored(lv) && !lv_is_raid(lv) &&
+	    !mirror_warning_printed && !ignore_lvm_mirrors()) {
+		log_print("Scanning mirrors for LVM labels is enabled.\n"
+			  "  It is possible for this to cause I/O hangs and stuck LVM processes.\n"
+			  "  See 'ignore_lvm_mirrors' in the LVM configuation file for details.");
+		mirror_warning_printed = 1;
+	}
+
 	if (!(dm = dev_manager_create(lv->vg->cmd, lv->vg->name, (lv->status & PVMOVE) ? 0 : 1)))
 		return_0;