openwrt/target/linux/generic/patches-3.9/441-block2mtd_refresh.patch

--- a/drivers/mtd/devices/block2mtd.c
+++ b/drivers/mtd/devices/block2mtd.c
@@ -29,6 +29,8 @@ struct block2mtd_dev {
 	struct block_device *blkdev;
 	struct mtd_info mtd;
 	struct mutex write_mutex;
+	rwlock_t bdev_mutex;
+	char devname[0];
 };
 
 
@@ -80,6 +82,12 @@ static int block2mtd_erase(struct mtd_in
 	size_t len = instr->len;
 	int err;
 
+	read_lock(&dev->bdev_mutex);
+	if (!dev->blkdev) {
+		err = -EINVAL;
+		goto done;
+	}
+
 	instr->state = MTD_ERASING;
 	mutex_lock(&dev->write_mutex);
 	err = _block2mtd_erase(dev, from, len);
@@ -91,6 +99,10 @@ static int block2mtd_erase(struct mtd_in
 		instr->state = MTD_ERASE_DONE;
 
 	mtd_erase_callback(instr);
+
+done:
+	read_unlock(&dev->bdev_mutex);
+
 	return err;
 }
 
@@ -102,7 +114,13 @@ static int block2mtd_read(struct mtd_inf
 	struct page *page;
 	int index = from >> PAGE_SHIFT;
 	int offset = from & (PAGE_SIZE-1);
-	int cpylen;
+	int cpylen, err = 0;
+
+	read_lock(&dev->bdev_mutex);
+	if (!dev->blkdev || (from > mtd->size)) {
+		err = -EINVAL;
+		goto done;
+	}
 
 	while (len) {
 		if ((offset + len) > PAGE_SIZE)
@@ -112,8 +130,10 @@ static int block2mtd_read(struct mtd_inf
 		len = len - cpylen;
 
 		page = page_read(dev->blkdev->bd_inode->i_mapping, index);
-		if (IS_ERR(page))
+		if (IS_ERR(page)) {
 			return PTR_ERR(page);
+			goto done;
+		}
 
 		memcpy(buf, page_address(page) + offset, cpylen);
 		page_cache_release(page);
@@ -124,7 +144,10 @@ static int block2mtd_read(struct mtd_inf
 		offset = 0;
 		index++;
 	}
-	return 0;
+
+done:
+	read_unlock(&dev->bdev_mutex);
+	return err;
 }
 
 
@@ -173,13 +196,22 @@ static int block2mtd_write(struct mtd_in
 		size_t *retlen, const u_char *buf)
 {
 	struct block2mtd_dev *dev = mtd->priv;
-	int err;
+	int err = 0;
+
+	read_lock(&dev->bdev_mutex);
+	if (!dev->blkdev) {
+		err = -EINVAL;
+		goto done;
+	}
 
 	mutex_lock(&dev->write_mutex);
 	err = _block2mtd_write(dev, buf, to, len, retlen);
 	mutex_unlock(&dev->write_mutex);
 	if (err > 0)
 		err = 0;
+
+done:
+	read_unlock(&dev->bdev_mutex);
 	return err;
 }
 
@@ -188,33 +220,110 @@ static int block2mtd_write(struct mtd_in
 static void block2mtd_sync(struct mtd_info *mtd)
 {
 	struct block2mtd_dev *dev = mtd->priv;
+	read_lock(&dev->bdev_mutex);
+	if (dev->blkdev)
 	sync_blockdev(dev->blkdev);
+	read_unlock(&dev->bdev_mutex);
+
 	return;
 }
 
 
+static int _open_bdev(struct block2mtd_dev *dev)
+{
+	const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
+	struct block_device *bdev;
+
+	/* Get a handle on the device */
+	bdev = blkdev_get_by_path(dev->devname, mode, dev);
+#ifndef MODULE
+	if (IS_ERR(bdev)) {
+		dev_t devt;
+
+		/* We might not have rootfs mounted at this point. Try
+		   to resolve the device name by other means. */
+
+		devt = name_to_dev_t(dev->devname);
+		if (devt)
+			bdev = blkdev_get_by_dev(devt, mode, dev);
+	}
+#endif
+
+	if (IS_ERR(bdev)) {
+		ERROR("error: cannot open device %s", dev->devname);
+		return 1;
+	}
+	dev->blkdev = bdev;
+
+	if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
+		ERROR("attempting to use an MTD device as a block device");
+		return 1;
+	}
+
+	return 0;
+}
+
+static void _close_bdev(struct block2mtd_dev *dev)
+{
+	struct block_device *bdev;
+
+	if (!dev->blkdev)
+		return;
+
+	bdev = dev->blkdev;
+	invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping, 0, -1);
+	blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
+	dev->blkdev = NULL;
+}
+
 static void block2mtd_free_device(struct block2mtd_dev *dev)
 {
 	if (!dev)
 		return;
 
 	kfree(dev->mtd.name);
-
-	if (dev->blkdev) {
-		invalidate_mapping_pages(dev->blkdev->bd_inode->i_mapping,
-					0, -1);
-		blkdev_put(dev->blkdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
-	}
-
+	_close_bdev(dev);
 	kfree(dev);
 }
 
 
-/* FIXME: ensure that mtd->size % erase_size == 0 */
-static struct block2mtd_dev *add_device(char *devname, int erase_size, const char *mtdname)
+static int block2mtd_refresh(struct mtd_info *mtd)
 {
-	const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
+	struct block2mtd_dev *dev = mtd->priv;
 	struct block_device *bdev;
+	dev_t devt;
+	int err = 0;
+
+	/* no other mtd function can run at this point */
+	write_lock(&dev->bdev_mutex);
+
+	/* get the device number for the whole disk */
+	devt = MKDEV(MAJOR(dev->blkdev->bd_dev), 0);
+
+	/* close the old block device */
+	_close_bdev(dev);
+
+	/* open the whole disk, issue a partition rescan, then */
+	bdev = blkdev_get_by_dev(devt, FMODE_WRITE | FMODE_READ, mtd);
+	if (!bdev || !bdev->bd_disk)
+		err = -EINVAL;
+#ifndef CONFIG_MTD_BLOCK2MTD_MODULE
+	else
+		err = rescan_partitions(bdev->bd_disk, bdev);
+#endif
+	if (bdev)
+		blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);
+
+	/* try to open the partition block device again */
+	_open_bdev(dev);
+	write_unlock(&dev->bdev_mutex);
+
+	return err;
+}
+
+/* FIXME: ensure that mtd->size % erase_size == 0 */
+static struct block2mtd_dev *add_device(char *devname, int erase_size, char *mtdname)
+{
 	struct block2mtd_dev *dev;
 	struct mtd_partition *part;
 	char *name;
@@ -222,36 +331,17 @@ static struct block2mtd_dev *add_device(
 	if (!devname)
 		return NULL;
 
-	dev = kzalloc(sizeof(struct block2mtd_dev), GFP_KERNEL);
+	dev = kzalloc(sizeof(struct block2mtd_dev) + strlen(devname) + 1, GFP_KERNEL);
 	if (!dev)
 		return NULL;
 
-	/* Get a handle on the device */
-	bdev = blkdev_get_by_path(devname, mode, dev);
-#ifndef MODULE
-	if (IS_ERR(bdev)) {
+	strcpy(dev->devname, devname);
 
-		/* We might not have rootfs mounted at this point. Try
-		   to resolve the device name by other means. */
-
-		dev_t devt = name_to_dev_t(devname);
-		if (devt)
-			bdev = blkdev_get_by_dev(devt, mode, dev);
-	}
-#endif
-
-	if (IS_ERR(bdev)) {
-		ERROR("error: cannot open device %s", devname);
-		goto devinit_err;
-	}
-	dev->blkdev = bdev;
-
-	if (MAJOR(bdev->bd_dev) == MTD_BLOCK_MAJOR) {
-		ERROR("attempting to use an MTD device as a block device");
+	if (_open_bdev(dev))
 		goto devinit_err;
-	}
 
 	mutex_init(&dev->write_mutex);
+	rwlock_init(&dev->bdev_mutex);
 
 	/* Setup the MTD structure */
 	/* make the name contain the block device in */
@@ -276,6 +366,7 @@ static struct block2mtd_dev *add_device(
 	dev->mtd._read = block2mtd_read;
 	dev->mtd.priv = dev;
 	dev->mtd.owner = THIS_MODULE;
+	dev->mtd.refresh_device = block2mtd_refresh;
 
 	part = kzalloc(sizeof(struct mtd_partition), GFP_KERNEL);
 	part->name = name;