2 files changed, 87 insertions, 28 deletions

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 4b54618b4159..f3481d922206 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -295,19 +295,55 @@ retry:
                 DMWARN("remove_all left %d open device(s)", dev_skipped);
 }
 
+/*
+ * Set the uuid of a hash_cell that isn't already set.
+ */
+static void __set_cell_uuid(struct hash_cell *hc, char *new_uuid)
+{
+        mutex_lock(&dm_hash_cells_mutex);
+        hc->uuid = new_uuid;
+        mutex_unlock(&dm_hash_cells_mutex);
+
+        list_add(&hc->uuid_list, _uuid_buckets + hash_str(new_uuid));
+}
+
+/*
+ * Changes the name of a hash_cell and returns the old name for
+ * the caller to free.
+ */
+static char *__change_cell_name(struct hash_cell *hc, char *new_name)
+{
+        char *old_name;
+
+        /*
+         * Rename and move the name cell.
+         */
+        list_del(&hc->name_list);
+        old_name = hc->name;
+
+        mutex_lock(&dm_hash_cells_mutex);
+        hc->name = new_name;
+        mutex_unlock(&dm_hash_cells_mutex);
+
+        list_add(&hc->name_list, _name_buckets + hash_str(new_name));
+
+        return old_name;
+}
+
 static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
                                             const char *new)
 {
-        char *new_name, *old_name;
+        char *new_data, *old_name = NULL;
         struct hash_cell *hc;
         struct dm_table *table;
         struct mapped_device *md;
+        unsigned change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
 
         /*
          * duplicate new.
          */
-        new_name = kstrdup(new, GFP_KERNEL);
-        if (!new_name)
+        new_data = kstrdup(new, GFP_KERNEL);
+        if (!new_data)
                 return ERR_PTR(-ENOMEM);
 
         down_write(&_hash_lock);
@@ -315,13 +351,19 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
         /*
          * Is new free ?
          */
-        hc = __get_name_cell(new);
+        if (change_uuid)
+                hc = __get_uuid_cell(new);
+        else
+                hc = __get_name_cell(new);
+
         if (hc) {
-                DMWARN("asked to rename to an already-existing name %s -> %s",
+                DMWARN("Unable to change %s on mapped device %s to one that "
+                       "already exists: %s",
+                       change_uuid ? "uuid" : "name",
                        param->name, new);
                 dm_put(hc->md);
                 up_write(&_hash_lock);
-                kfree(new_name);
+                kfree(new_data);
                 return ERR_PTR(-EBUSY);
         }
 
@@ -330,22 +372,30 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
          */
         hc = __get_name_cell(param->name);
         if (!hc) {
-                DMWARN("asked to rename a non-existent device %s -> %s",
-                       param->name, new);
+                DMWARN("Unable to rename non-existent device, %s to %s%s",
+                       param->name, change_uuid ? "uuid " : "", new);
                 up_write(&_hash_lock);
-                kfree(new_name);
+                kfree(new_data);
                 return ERR_PTR(-ENXIO);
         }
 
         /*
-         * rename and move the name cell.
+         * Does this device already have a uuid?
          */
-        list_del(&hc->name_list);
-        old_name = hc->name;
-        mutex_lock(&dm_hash_cells_mutex);
-        hc->name = new_name;
-        mutex_unlock(&dm_hash_cells_mutex);
-        list_add(&hc->name_list, _name_buckets + hash_str(new_name));
+        if (change_uuid && hc->uuid) {
+                DMWARN("Unable to change uuid of mapped device %s to %s "
+                       "because uuid is already set to %s",
+                       param->name, new, hc->uuid);
+                dm_put(hc->md);
+                up_write(&_hash_lock);
+                kfree(new_data);
+                return ERR_PTR(-EINVAL);
+        }
+
+        if (change_uuid)
+                __set_cell_uuid(hc, new_data);
+        else
+                old_name = __change_cell_name(hc, new_data);
 
         /*
          * Wake up any dm event waiters.
@@ -774,21 +824,24 @@ static int invalid_str(char *str, void *end)
 static int dev_rename(struct dm_ioctl *param, size_t param_size)
 {
         int r;
-        char *new_name = (char *) param + param->data_start;
+        char *new_data = (char *) param + param->data_start;
         struct mapped_device *md;
+        unsigned change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
 
-        if (new_name < param->data ||
-            invalid_str(new_name, (void *) param + param_size) ||
-            strlen(new_name) > DM_NAME_LEN - 1) {
-                DMWARN("Invalid new logical volume name supplied.");
+        if (new_data < param->data ||
+            invalid_str(new_data, (void *) param + param_size) ||
+            strlen(new_data) > (change_uuid ? DM_UUID_LEN - 1 : DM_NAME_LEN - 1)) {
+                DMWARN("Invalid new mapped device name or uuid string supplied.");
                 return -EINVAL;
         }
 
-        r = check_name(new_name);
-        if (r)
-                return r;
+        if (!change_uuid) {
+                r = check_name(new_data);
+                if (r)
+                        return r;
+        }
 
-        md = dm_hash_rename(param, new_name);
+        md = dm_hash_rename(param, new_data);
         if (IS_ERR(md))
                 return PTR_ERR(md);
 
diff --git a/include/linux/dm-ioctl.h b/include/linux/dm-ioctl.h
index 49eab360d5d4..e453e1174ae1 100644
--- a/include/linux/dm-ioctl.h
+++ b/include/linux/dm-ioctl.h
@@ -44,7 +44,7 @@
  * Remove a device, destroy any tables.
  *
  * DM_DEV_RENAME:
- * Rename a device.
+ * Rename a device or set its uuid if none was previously supplied.
  *
  * DM_SUSPEND:
  * This performs both suspend and resume, depending which flag is
@@ -267,9 +267,9 @@ enum {
 #define DM_DEV_SET_GEOMETRY     _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
 
 #define DM_VERSION_MAJOR        4
-#define DM_VERSION_MINOR        18
+#define DM_VERSION_MINOR        19
 #define DM_VERSION_PATCHLEVEL   0
-#define DM_VERSION_EXTRA        "-ioctl (2010-06-29)"
+#define DM_VERSION_EXTRA        "-ioctl (2010-10-14)"
 
 /* Status bits */
 #define DM_READONLY_FLAG        (1 << 0) /* In/Out */
@@ -322,4 +322,10 @@ enum {
  */
 #define DM_UEVENT_GENERATED_FLAG        (1 << 13) /* Out */
 
+/*
+ * If set, rename changes the uuid not the name.  Only permitted
+ * if no uuid was previously supplied: an existing uuid cannot be changed.
+ */
+#define DM_UUID_FLAG                    (1 << 14) /* In */
+
 #endif                          /* _LINUX_DM_IOCTL_H */