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Re: [dm-devel] [PATCH] device-mapper: Allow setting of UUID via rename if not already set



On 10/08/2010 05:33 PM, Jonathan Brassow wrote:
> Peter, please add your "signed-off-by" if you approve of the changes
> (above my signed-off-by, because you are the creator).  It still would
> be nice to have a better header - not too many people will look at the
> bz, I think.  Better to say "There are times when we need to be able to
> set device UUIDs, like when...".
> 
> Looks like I had in mind the same things as Mike.  :)
> 
>  brassow
> 
How about:
 
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>
> Signed-off-by: Jonathan Brassow <jbrassow redhat com>
> 
> Index: linux-2.6/drivers/md/dm-ioctl.c
> ===================================================================
> --- linux-2.6.orig/drivers/md/dm-ioctl.c
> +++ linux-2.6/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_ren
>  	/*
>  	 * 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 +315,19 @@ static struct mapped_device *dm_hash_ren
>  	/*
>  	 * Is new free ?
>  	 */
> -	hc = __get_name_cell(new);
> +	if (param->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",
> +		       (param->flags & DM_NEW_UUID_FLAG) ? "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 +336,45 @@ static struct mapped_device *dm_hash_ren
>  	 */
>  	hc = __get_name_cell(param->name);
>  	if (!hc) {
> -		DMWARN("asked to rename a non-existent device %s -> %s",
> +		DMWARN("Unable to rename non-existent device, %s to %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("Unable to change uuid of device, %s because "
> +			       "uuid is already set to %s",
> +			       param->name, hc->uuid);
> +			up_write(&_hash_lock);
> +			kfree(new_data);
> +			return ERR_PTR(-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.
> @@ -361,7 +390,7 @@ static struct mapped_device *dm_hash_ren
>  
>  	md = hc->md;
>  	up_write(&_hash_lock);
> -	kfree(old_name);
> +	kfree(old_data);
>  
>  	return md;
>  }
> @@ -774,21 +803,30 @@ static int invalid_str(char *str, void *
>  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) {
> +		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;
> +	}
>  
> -	md = dm_hash_rename(param, new_name);
> +	md = dm_hash_rename(param, new_data);
>  	if (IS_ERR(md))
>  		return PTR_ERR(md);
>  
> Index: linux-2.6/include/linux/dm-ioctl.h
> ===================================================================
> --- linux-2.6.orig/include/linux/dm-ioctl.h
> +++ linux-2.6/include/linux/dm-ioctl.h
> @@ -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 (2010-10-07)"
>  
>  /* Status bits */
>  #define DM_READONLY_FLAG	(1 << 0) /* In/Out */
> @@ -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 */
> 
> 


-- 
        Peter

Growth for the sake of growth is the ideology of the cancer cell.

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