mtd: block2mtd: factor the early block device open logic into a helper

Simplify add_device a bit by splitting out the cumbersome early boot logic
into a separate helper.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/r/20230531125535.676098-23-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/mtd/devices/block2mtd.c

@@ -215,34 +215,18 @@ static void block2mtd_free_device(struct block2mtd_dev *dev)
 	kfree(dev);
 }
 
-
-static struct block2mtd_dev *add_device(char *devname, int erase_size,
-		char *label, int timeout)
+static struct block_device *mdtblock_early_get_bdev(const char *devname,
+		fmode_t mode, int timeout, struct block2mtd_dev *dev)
 {
+	struct block_device *bdev = ERR_PTR(-ENODEV);
 #ifndef MODULE
 	int i;
-#endif
-	const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
-	struct block_device *bdev;
-	struct block2mtd_dev *dev;
-	char *name;
-
-	if (!devname)
-		return NULL;
-
-	dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
-	if (!dev)
-		return NULL;
 
-	/* Get a handle on the device */
-	bdev = blkdev_get_by_path(devname, mode, dev, NULL);
-
-#ifndef MODULE
 	/*
 	 * We might not have the root device mounted at this point.
 	 * Try to resolve the device name by other means.
 	 */
-	for (i = 0; IS_ERR(bdev) && i <= timeout; i++) {
+	for (i = 0; i <= timeout; i++) {
 		dev_t devt;
 
 		if (i)
@@ -254,12 +238,35 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size,
 			msleep(1000);
 		wait_for_device_probe();
 
-		if (early_lookup_bdev(devname, &devt))
-			continue;
-		bdev = blkdev_get_by_dev(devt, mode, dev, NULL);
+		if (!early_lookup_bdev(devname, &devt)) {
+			bdev = blkdev_get_by_dev(devt, mode, dev, NULL);
+			if (!IS_ERR(bdev))
+				break;
+		}
 	}
 #endif
+	return bdev;
+}
+
+static struct block2mtd_dev *add_device(char *devname, int erase_size,
+		char *label, int timeout)
+{
+	const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
+	struct block_device *bdev;
+	struct block2mtd_dev *dev;
+	char *name;
 
+	if (!devname)
+		return NULL;
+
+	dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
+	if (!dev)
+		return NULL;
+
+	/* Get a handle on the device */
+	bdev = blkdev_get_by_path(devname, mode, dev, NULL);
+	if (IS_ERR(bdev))
+		bdev = mdtblock_early_get_bdev(devname, mode, timeout, dev);
 	if (IS_ERR(bdev)) {
 		pr_err("error: cannot open device %s\n", devname);
 		goto err_free_block2mtd;