1 files changed, 25 insertions, 5 deletions

diff --git a/drivers/md/dm-snap-persistent.c b/drivers/md/dm-snap-persistent.c
index bf71583296f7..117a05e40090 100644
--- a/drivers/md/dm-snap-persistent.c
+++ b/drivers/md/dm-snap-persistent.c
@@ -7,6 +7,7 @@
 
 #include "dm-exception-store.h"
 
+#include <linux/ctype.h>
 #include <linux/mm.h>
 #include <linux/pagemap.h>
 #include <linux/vmalloc.h>
@@ -843,10 +844,10 @@ static void persistent_drop_snapshot(struct dm_exception_store *store)
                 DMWARN("write header failed");
 }
 
-static int persistent_ctr(struct dm_exception_store *store,
-                          unsigned argc, char **argv)
+static int persistent_ctr(struct dm_exception_store *store, char *options)
 {
         struct pstore *ps;
+        int r;
 
         /* allocate the pstore */
         ps = kzalloc(sizeof(*ps), GFP_KERNEL);
@@ -868,14 +869,32 @@ static int persistent_ctr(struct dm_exception_store *store,
 
         ps->metadata_wq = alloc_workqueue("ksnaphd", WQ_MEM_RECLAIM, 0);
         if (!ps->metadata_wq) {
-                kfree(ps);
                 DMERR("couldn't start header metadata update thread");
-                return -ENOMEM;
+                r = -ENOMEM;
+                goto err_workqueue;
+        }
+
+        if (options) {
+                char overflow = toupper(options[0]);
+                if (overflow == 'O')
+                        store->userspace_supports_overflow = true;
+                else {
+                        DMERR("Unsupported persistent store option: %s", options);
+                        r = -EINVAL;
+                        goto err_options;
+                }
         }
 
         store->context = ps;
 
         return 0;
+
+err_options:
+        destroy_workqueue(ps->metadata_wq);
+err_workqueue:
+        kfree(ps);
+
+        return r;
 }
 
 static unsigned persistent_status(struct dm_exception_store *store,
@@ -888,7 +907,8 @@ static unsigned persistent_status(struct dm_exception_store *store,
         case STATUSTYPE_INFO:
                 break;
         case STATUSTYPE_TABLE:
-                DMEMIT(" P %llu", (unsigned long long)store->chunk_size);
+                DMEMIT(" %s %llu", store->userspace_supports_overflow ? "PO" : "P",
+                       (unsigned long long)store->chunk_size);
         }
 
         return sz;