dm ioctl: allow rename to fill empty uuid

Allow the uuid of a mapped device to be set after device creation. Previously the uuid (which is optional) could only be set by DM_DEV_CREATE. If no uuid was supplied it could not be set later. Sometimes 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. This patch extends DM_DEV_RENAME to accept a uuid accompanied by a new flag DM_UUID_FLAG. This can only be done once and if no uuid was previously supplied. It cannot be used to change an existing uuid. DM_VERSION_MINOR is also bumped to 19 to indicate this interface extension is available. Signed-off-by: Peter Jones <pjones@redhat.com> Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>

dm ioctl: allow rename to fill empty uuid
Allow the uuid of a mapped device to be set after device creation. Previously the uuid (which is optional) could only be set by DM_DEV_CREATE. If no uuid was supplied it could not be set later. Sometimes 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. This patch extends DM_DEV_RENAME to accept a uuid accompanied by a new flag DM_UUID_FLAG. This can only be done once and if no uuid was previously supplied. It cannot be used to change an existing uuid. DM_VERSION_MINOR is also bumped to 19 to indicate this interface extension is available. Signed-off-by: Peter Jones <pjones@redhat.com> Signed-off-by: Jonathan Brassow <jbrassow@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Peter Jones · Alasdair G Kergon
1 parent d9bf0b508d
Showing 2 changed files with 87 additions and 28 deletions Side-by-side Diff
drivers/md/dm-ioctl.c
include/linux/dm-ioctl.h
@@ -295,19 +295,55 @@
 		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 @@
 	/*
 	 * 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);
 	}
  
  
  
  
  
@@ -330,23 +372,31 @@
 	 */
 	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 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);
  
@@ -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 @@
 #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 */
@@ -321,6 +321,12 @@
  * If set, a uevent was generated for which the caller may need to wait.
  */
 #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 */
...	...	@@ -295,19 +295,55 @@
295	295	DMWARN("remove_all left %d open device(s)", dev_skipped);
296	296	}
297	297
	298	+/*
	299	+ * Set the uuid of a hash_cell that isn't already set.
	300	+ */
	301	+static void __set_cell_uuid(struct hash_cell hc, char new_uuid)
	302	+{
	303	+ mutex_lock(&dm_hash_cells_mutex);
	304	+ hc->uuid = new_uuid;
	305	+ mutex_unlock(&dm_hash_cells_mutex);
	306	+
	307	+ list_add(&hc->uuid_list, _uuid_buckets + hash_str(new_uuid));
	308	+}
	309	+
	310	+/*
	311	+ * Changes the name of a hash_cell and returns the old name for
	312	+ * the caller to free.
	313	+ */
	314	+static char __change_cell_name(struct hash_cell hc, char *new_name)
	315	+{
	316	+ char *old_name;
	317	+
	318	+ /*
	319	+ * Rename and move the name cell.
	320	+ */
	321	+ list_del(&hc->name_list);
	322	+ old_name = hc->name;
	323	+
	324	+ mutex_lock(&dm_hash_cells_mutex);
	325	+ hc->name = new_name;
	326	+ mutex_unlock(&dm_hash_cells_mutex);
	327	+
	328	+ list_add(&hc->name_list, _name_buckets + hash_str(new_name));
	329	+
	330	+ return old_name;
	331	+}
	332	+
298	333	static struct mapped_device dm_hash_rename(struct dm_ioctl param,
299	334	const char *new)
300	335	{
301		- char new_name, old_name;
	336	+ char new_data, old_name = NULL;
302	337	struct hash_cell *hc;
303	338	struct dm_table *table;
304	339	struct mapped_device *md;
	340	+ unsigned change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
305	341
306	342	/*
307	343	* duplicate new.
308	344	*/
309		- new_name = kstrdup(new, GFP_KERNEL);
310		- if (!new_name)
	345	+ new_data = kstrdup(new, GFP_KERNEL);
	346	+ if (!new_data)
311	347	return ERR_PTR(-ENOMEM);
312	348
313	349	down_write(&_hash_lock);
314	350
315	351
...	...	@@ -315,13 +351,19 @@
315	351	/*
316	352	* Is new free ?
317	353	*/
318		- hc = __get_name_cell(new);
	354	+ if (change_uuid)
	355	+ hc = __get_uuid_cell(new);
	356	+ else
	357	+ hc = __get_name_cell(new);
	358	+
319	359	if (hc) {
320		- DMWARN("asked to rename to an already-existing name %s -> %s",
	360	+ DMWARN("Unable to change %s on mapped device %s to one that "
	361	+ "already exists: %s",
	362	+ change_uuid ? "uuid" : "name",
321	363	param->name, new);
322	364	dm_put(hc->md);
323	365	up_write(&_hash_lock);
324		- kfree(new_name);
	366	+ kfree(new_data);
325	367	return ERR_PTR(-EBUSY);
326	368	}
327	369
328	370
329	371
330	372
331	373
...	...	@@ -330,23 +372,31 @@
330	372	*/
331	373	hc = __get_name_cell(param->name);
332	374	if (!hc) {
333		- DMWARN("asked to rename a non-existent device %s -> %s",
334		- param->name, new);
	375	+ DMWARN("Unable to rename non-existent device, %s to %s%s",
	376	+ param->name, change_uuid ? "uuid " : "", new);
335	377	up_write(&_hash_lock);
336		- kfree(new_name);
	378	+ kfree(new_data);
337	379	return ERR_PTR(-ENXIO);
338	380	}
339	381
340	382	/*
341		- * rename and move the name cell.
	383	+ * Does this device already have a uuid?
342	384	*/
343		- list_del(&hc->name_list);
344		- old_name = hc->name;
345		- mutex_lock(&dm_hash_cells_mutex);
346		- hc->name = new_name;
347		- mutex_unlock(&dm_hash_cells_mutex);
348		- list_add(&hc->name_list, _name_buckets + hash_str(new_name));
	385	+ if (change_uuid && hc->uuid) {
	386	+ DMWARN("Unable to change uuid of mapped device %s to %s "
	387	+ "because uuid is already set to %s",
	388	+ param->name, new, hc->uuid);
	389	+ dm_put(hc->md);
	390	+ up_write(&_hash_lock);
	391	+ kfree(new_data);
	392	+ return ERR_PTR(-EINVAL);
	393	+ }
349	394
	395	+ if (change_uuid)
	396	+ __set_cell_uuid(hc, new_data);
	397	+ else
	398	+ old_name = __change_cell_name(hc, new_data);
	399	+
350	400	/*
351	401	* Wake up any dm event waiters.
352	402	*/
353	403
354	404
355	405
356	406
...	...	@@ -774,21 +824,24 @@
774	824	static int dev_rename(struct dm_ioctl *param, size_t param_size)
775	825	{
776	826	int r;
777		- char new_name = (char ) param + param->data_start;
	827	+ char new_data = (char ) param + param->data_start;
778	828	struct mapped_device *md;
	829	+ unsigned change_uuid = (param->flags & DM_UUID_FLAG) ? 1 : 0;
779	830
780		- if (new_name < param->data \|\|
781		- invalid_str(new_name, (void *) param + param_size) \|\|
782		- strlen(new_name) > DM_NAME_LEN - 1) {
783		- DMWARN("Invalid new logical volume name supplied.");
	831	+ if (new_data < param->data \|\|
	832	+ invalid_str(new_data, (void *) param + param_size) \|\|
	833	+ strlen(new_data) > (change_uuid ? DM_UUID_LEN - 1 : DM_NAME_LEN - 1)) {
	834	+ DMWARN("Invalid new mapped device name or uuid string supplied.");
784	835	return -EINVAL;
785	836	}
786	837
787		- r = check_name(new_name);
788		- if (r)
789		- return r;
	838	+ if (!change_uuid) {
	839	+ r = check_name(new_data);
	840	+ if (r)
	841	+ return r;
	842	+ }
790	843
791		- md = dm_hash_rename(param, new_name);
	844	+ md = dm_hash_rename(param, new_data);
792	845	if (IS_ERR(md))
793	846	return PTR_ERR(md);
794	847
...	...	@@ -44,7 +44,7 @@
44	44	* Remove a device, destroy any tables.
45	45	*
46	46	* DM_DEV_RENAME:
47		- * Rename a device.
	47	+ * Rename a device or set its uuid if none was previously supplied.
48	48	*
49	49	* DM_SUSPEND:
50	50	* This performs both suspend and resume, depending which flag is
51	51
...	...	@@ -267,9 +267,9 @@
267	267	#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
268	268
269	269	#define DM_VERSION_MAJOR 4
270		-#define DM_VERSION_MINOR 18
	270	+#define DM_VERSION_MINOR 19
271	271	#define DM_VERSION_PATCHLEVEL 0
272		-#define DM_VERSION_EXTRA "-ioctl (2010-06-29)"
	272	+#define DM_VERSION_EXTRA "-ioctl (2010-10-14)"
273	273
274	274	/* Status bits */
275	275	#define DM_READONLY_FLAG (1 << 0) /* In/Out */
...	...	@@ -321,6 +321,12 @@
321	321	* If set, a uevent was generated for which the caller may need to wait.
322	322	*/
323	323	#define DM_UEVENT_GENERATED_FLAG (1 << 13) /* Out */
	324	+
	325	+/*
	326	+ * If set, rename changes the uuid not the name. Only permitted
	327	+ * if no uuid was previously supplied: an existing uuid cannot be changed.
	328	+ */
	329	+#define DM_UUID_FLAG (1 << 14) /* In */
324	330
325	331	#endif /* _LINUX_DM_IOCTL_H */