From ce5fa9851090cc5f3de4139bf0f343eb78d1c568 Mon Sep 17 00:00:00 2001
From: Peter Jones <pjones@redhat.com>
Date: Mon, 11 Oct 2010 15:49:28 -0400
Subject: [PATCH] device-mapper: Allow setting of UUID via rename if not already set

This makes it possible to use DM_DEV_RENAME to add a uuid to a device so
long as one has not been previously set either with DM_DEV_CREATE or
with DM_DEV_RENAME. This is needed because sometimes in it's necessary
to create the device before the uuid is known, and in such cases the
uuid must be filled in after the creation.

Also bump the minor number to 19.

Signed-off-by: Peter Jones <pjones@redhat.com>
---
 drivers/md/dm-ioctl.c    |   95 ++++++++++++++++++++++++++++++++--------------
 include/linux/dm-ioctl.h |   11 ++++-
 2 files changed, 74 insertions(+), 32 deletions(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index bb6bdc8..d102269 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -298,15 +298,15 @@ retry:
 static int dm_hash_rename(uint32_t cookie, uint32_t *flags, const char *old,
 			  const char *new)
 {
-	char *new_name, *old_name;
+	char *new_data, *old_data;
 	struct hash_cell *hc;
 	struct dm_table *table;
 
 	/*
 	 * duplicate new.
 	 */
-	new_name = kstrdup(new, GFP_KERNEL);
-	if (!new_name)
+	new_data = kstrdup(new, GFP_KERNEL);
+	if (!new_data)
 		return -ENOMEM;
 
 	down_write(&_hash_lock);
@@ -314,13 +314,18 @@ static int dm_hash_rename(uint32_t cookie, uint32_t *flags, const char *old,
 	/*
 	 * Is new free ?
 	 */
-	hc = __get_name_cell(new);
+	if (*flags & DM_NEW_UUID_FLAG)
+		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 device, %s to one that "
+		       "already exists: %s",
+		       (*flags & DM_NEW_UUID_FLAG) ? "uuid" : "name",
 		       old, new);
 		dm_put(hc->md);
 		up_write(&_hash_lock);
-		kfree(new_name);
+		kfree(new_data);
 		return -EBUSY;
 	}
 
@@ -329,22 +334,46 @@ static int dm_hash_rename(uint32_t cookie, uint32_t *flags, const char *old,
 	 */
 	hc = __get_name_cell(old);
 	if (!hc) {
-		DMWARN("asked to rename a non existent device %s -> %s",
+		DMWARN("Unable to rename non-existent device, %s to %s",
 		       old, new);
 		up_write(&_hash_lock);
-		kfree(new_name);
+		kfree(new_data);
 		return -ENXIO;
 	}
 
-	/*
-	 * 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));
+	if (*flags & DM_NEW_UUID_FLAG) {
+		/*
+		 * Does this device already have a uuid?
+		 */
+		if (hc->uuid) {
+			DMWARN("Unable to change uuid of device, %s because "
+			       "uuid is already set to %s",
+			       old, hc->uuid);
+	 		dm_put(hc->md);
+			up_write(&_hash_lock);
+			kfree(new_data);
+			return -EINVAL;
+		}
+		/*
+		 * change uuid and move the uuid cell.
+		 */
+		list_del(&hc->uuid_list);
+		old_data = hc->uuid;
+		mutex_lock(&dm_hash_cells_mutex);
+		hc->uuid = new_data;
+		mutex_unlock(&dm_hash_cells_mutex);
+		list_add(&hc->uuid_list, _uuid_buckets + hash_str(new_data));
+	} else {
+		/*
+		 * rename and move the name cell.
+		 */
+		list_del(&hc->name_list);
+		old_data = hc->name;
+		mutex_lock(&dm_hash_cells_mutex);
+		hc->name = new_data;
+		mutex_unlock(&dm_hash_cells_mutex);
+		list_add(&hc->name_list, _name_buckets + hash_str(new_data));
+	}
 
 	/*
 	 * Wake up any dm event waiters.
@@ -360,7 +388,7 @@ static int dm_hash_rename(uint32_t cookie, uint32_t *flags, const char *old,
 
 	dm_put(hc->md);
 	up_write(&_hash_lock);
-	kfree(old_name);
+	kfree(old_data);
 	return 0;
 }
 
@@ -773,23 +801,32 @@ 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;
 
-	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.");
-		return -EINVAL;
-	}
+	if (param->flags & DM_NEW_UUID_FLAG) {
+		if (new_data < param->data ||
+		    invalid_str(new_data, (void *) param + param_size) ||
+		    strlen(new_data) > DM_UUID_LEN - 1) {
+			DMWARN("Invalid new device uuid supplied.");
+			return -EINVAL;
+		}
+	} else {
+		if (new_data < param->data ||
+		    invalid_str(new_data, (void *) param + param_size) ||
+		    strlen(new_data) > DM_NAME_LEN - 1) {
+			DMWARN("Invalid new device name supplied.");
+			return -EINVAL;
+		}
 
-	r = check_name(new_name);
-	if (r)
-		return r;
+		r = check_name(new_data);
+		if (r)
+			return r;
+	}
 
 	param->data_size = 0;
 
 	return dm_hash_rename(param->event_nr, &param->flags, param->name,
-			      new_name);
+			      new_data);
 }
 
 static int dev_set_geometry(struct dm_ioctl *param, size_t param_size)
diff --git a/include/linux/dm-ioctl.h b/include/linux/dm-ioctl.h
index 2c445e1..3bbcb3a 100644
--- a/include/linux/dm-ioctl.h
+++ b/include/linux/dm-ioctl.h
@@ -266,9 +266,9 @@ 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	17
-#define DM_VERSION_PATCHLEVEL	0
-#define DM_VERSION_EXTRA	"-ioctl (2010-03-05)"
+#define DM_VERSION_MINOR	19
+#define DM_VERSION_PATCHLEVEL	1
+#define DM_VERSION_EXTRA	"-ioctl (2010-10-12)"
 
 /* Status bits */
 #define DM_READONLY_FLAG	(1 << 0) /* In/Out */
@@ -321,4 +321,9 @@ enum {
  */
 #define DM_UEVENT_GENERATED_FLAG	(1 << 13) /* Out */
 
+/*
+ * If set, rename operates on uuid, not name.
+ */
+#define DM_NEW_UUID_FLAG        (1 << 14) /* In */
+
 #endif				/* _LINUX_DM_IOCTL_H */
-- 
1.7.2.3