btrfs: device add and remove: use GFP_KERNEL

We can safely use GFP_KERNEL in the functions called from the ioctl
handlers.
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/volumes.c

@@ -138,7 +138,7 @@ static struct btrfs_fs_devices *__alloc_fs_devices(void)
 {
 	struct btrfs_fs_devices *fs_devs;
 
-	fs_devs = kzalloc(sizeof(*fs_devs), GFP_NOFS);
+	fs_devs = kzalloc(sizeof(*fs_devs), GFP_KERNEL);
 	if (!fs_devs)
 		return ERR_PTR(-ENOMEM);
 
@@ -220,7 +220,7 @@ static struct btrfs_device *__alloc_device(void)
 {
 	struct btrfs_device *dev;
 
-	dev = kzalloc(sizeof(*dev), GFP_NOFS);
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 	if (!dev)
 		return ERR_PTR(-ENOMEM);
 
@@ -733,7 +733,8 @@ static struct btrfs_fs_devices *clone_fs_devices(struct btrfs_fs_devices *orig)
 		 * uuid mutex so nothing we touch in here is going to disappear.
 		 */
 		if (orig_dev->name) {
-			name = rcu_string_strdup(orig_dev->name->str, GFP_NOFS);
+			name = rcu_string_strdup(orig_dev->name->str,
+					GFP_KERNEL);
 			if (!name) {
 				kfree(device);
 				goto error;
@@ -2287,7 +2288,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
 		goto error;
 	}
 
-	name = rcu_string_strdup(device_path, GFP_NOFS);
+	name = rcu_string_strdup(device_path, GFP_KERNEL);
 	if (!name) {
 		kfree(device);
 		ret = -ENOMEM;