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[dm-devel] [PATCH] Make it possible to set a uuid if one was not set during DM_DEV_CREATE.



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.
---
 drivers/md/dm-ioctl.c    |  113 ++++++++++++++++++++++++++++++++-------------
 include/linux/dm-ioctl.h |    5 ++
 2 files changed, 85 insertions(+), 33 deletions(-)

diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 3e39193..bd76846 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -298,7 +298,7 @@ retry:
 static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
 					    const char *new)
 {
-	char *new_name, *old_name;
+	char *new_data, *old_data;
 	struct hash_cell *hc;
 	struct dm_table *table;
 	struct mapped_device *md;
@@ -306,8 +306,8 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
 	/*
 	 * 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);
@@ -315,14 +315,28 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
 	/*
 	 * Is new free ?
 	 */
-	hc = __get_name_cell(new);
-	if (hc) {
-		DMWARN("asked to rename to an already-existing name %s -> %s",
-		       param->name, new);
-		dm_put(hc->md);
-		up_write(&_hash_lock);
-		kfree(new_name);
-		return ERR_PTR(-EBUSY);
+	if (param->flags & DM_NEW_UUID_FLAG) {
+		hc = __get_uuid_cell(new);
+		if (hc) {
+			DMWARN("asked to change uuid to an already-existing uuid"
+			       " %s -> %s",
+			       param->name, new);
+			dm_put(hc->md);
+			up_write(&_hash_lock);
+			kfree(new_data);
+			return ERR_PTR(-EBUSY);
+		}
+	} else {
+		hc = __get_name_cell(new);
+		if (hc) {
+			DMWARN("asked to rename to an already-existing name "
+			       "%s -> %s",
+			       param->name, new);
+			dm_put(hc->md);
+			up_write(&_hash_lock);
+			kfree(new_data);
+			return ERR_PTR(-EBUSY);
+		}
 	}
 
 	/*
@@ -333,19 +347,42 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
 		DMWARN("asked to rename a non-existent device %s -> %s",
 		       param->name, new);
 		up_write(&_hash_lock);
-		kfree(new_name);
+		kfree(new_data);
 		return ERR_PTR(-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 (param->flags & DM_NEW_UUID_FLAG) {
+		/*
+		 * Does this device already have a uuid?
+		 */
+		if (hc->uuid) {
+			DMWARN("asked to change uuid of device with uuid "
+			       "already set %s %s -> %s",
+			       param->name, hc->uuid, param->uuid);
+			up_write(&_hash_lock);
+			kfree(new_uuid);
+			return ERR_PTR(-EINVAL);
+		}
+		/*
+		 * reuuid 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.
@@ -361,7 +398,7 @@ static struct mapped_device *dm_hash_rename(struct dm_ioctl *param,
 
 	md = hc->md;
 	up_write(&_hash_lock);
-	kfree(old_name);
+	kfree(old_data);
 
 	return md;
 }
@@ -774,21 +811,31 @@ 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;
 
-	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) {
+		struct hash_cell *hc;
+		if (new_data < param->data ||
+		    invalid_str(new_data, (void *) param + param_size) ||
+		    strlen(new_data) > DM_UUID_LEN - 1) {
+			DMWARN("Invalid new logical volume 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 logical volume name supplied.");
+			return -EINVAL;
+		}
 
-	r = check_name(new_name);
-	if (r)
-		return r;
+		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 49eab36..8f1a610 100644
--- a/include/linux/dm-ioctl.h
+++ b/include/linux/dm-ioctl.h
@@ -322,4 +322,9 @@ 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 */
-- 
1.7.2.2


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