bdi: Provide bdi_register_va() and bdi_alloc()

Add function that registers bdi and takes va_list instead of variable
number of arguments.

Add bdi_alloc() as simple wrapper for NUMA-unaware users allocating BDI.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>

include/linux/backing-dev.h

@@ -30,6 +30,8 @@ void bdi_put(struct backing_dev_info *bdi);
 __printf(3, 4)
 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
 		const char *fmt, ...);
+int bdi_register_va(struct backing_dev_info *bdi, struct device *parent,
+		const char *fmt, va_list args);
 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
 int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner);
 void bdi_unregister(struct backing_dev_info *bdi);
@@ -37,6 +39,10 @@ void bdi_unregister(struct backing_dev_info *bdi);
 int __must_check bdi_setup_and_register(struct backing_dev_info *, char *);
 void bdi_destroy(struct backing_dev_info *bdi);
 struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id);
+static inline struct backing_dev_info *bdi_alloc(gfp_t gfp_mask)
+{
+	return bdi_alloc_node(gfp_mask, NUMA_NO_NODE);
+}
 
 void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
 			bool range_cyclic, enum wb_reason reason);

mm/backing-dev.c

@@ -856,18 +856,15 @@ struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id)
 	return bdi;
 }
 
-int bdi_register(struct backing_dev_info *bdi, struct device *parent,
-		const char *fmt, ...)
+int bdi_register_va(struct backing_dev_info *bdi, struct device *parent,
+		const char *fmt, va_list args)
 {
-	va_list args;
 	struct device *dev;
 
 	if (bdi->dev)	/* The driver needs to use separate queues per device */
 		return 0;
 
-	va_start(args, fmt);
 	dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
-	va_end(args);
 	if (IS_ERR(dev))
 		return PTR_ERR(dev);
 
@@ -884,6 +881,19 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
 	trace_writeback_bdi_register(bdi);
 	return 0;
 }
+EXPORT_SYMBOL(bdi_register_va);
+
+int bdi_register(struct backing_dev_info *bdi, struct device *parent,
+		const char *fmt, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, fmt);
+	ret = bdi_register_va(bdi, parent, fmt, args);
+	va_end(args);
+	return ret;
+}
 EXPORT_SYMBOL(bdi_register);
 
 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)