btrfs: move volume_mutex into the btrfs_rm_device()

A cleanup patch no functional change, we hold volume_mutex before
calling btrfs_rm_device, so move it into the function itself.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ioctl.c

@@ -2675,14 +2675,12 @@ static long btrfs_ioctl_rm_dev_v2(struct file *file, void __user *arg)
 		goto out;
 	}
 
-	mutex_lock(&fs_info->volume_mutex);
 	if (vol_args->flags & BTRFS_DEVICE_SPEC_BY_ID) {
 		ret = btrfs_rm_device(fs_info, NULL, vol_args->devid);
 	} else {
 		vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
 		ret = btrfs_rm_device(fs_info, vol_args->name, 0);
 	}
-	mutex_unlock(&fs_info->volume_mutex);
 	clear_bit(BTRFS_FS_EXCL_OP, &fs_info->flags);
 
 	if (!ret) {
@@ -2726,9 +2724,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
 	}
 
 	vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
-	mutex_lock(&fs_info->volume_mutex);
 	ret = btrfs_rm_device(fs_info, vol_args->name, 0);
-	mutex_unlock(&fs_info->volume_mutex);
 
 	if (!ret)
 		btrfs_info(fs_info, "disk deleted %s", vol_args->name);

fs/btrfs/volumes.c

@@ -1842,6 +1842,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 	u64 num_devices;
 	int ret = 0;
 
+	mutex_lock(&fs_info->volume_mutex);
 	mutex_lock(&uuid_mutex);
 
 	num_devices = fs_info->fs_devices->num_devices;
@@ -1956,6 +1957,7 @@ int btrfs_rm_device(struct btrfs_fs_info *fs_info, const char *device_path,
 
 out:
 	mutex_unlock(&uuid_mutex);
+	mutex_unlock(&fs_info->volume_mutex);
 	return ret;
 
 error_undo: