1 files changed, 58 insertions, 7 deletions

diff --git a/block/bdev.c b/block/bdev.c
index aea9143d8908..e4cfb7adb645 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -829,6 +829,28 @@ put_blkdev:
 }
 EXPORT_SYMBOL(blkdev_get_by_dev);
 
+struct bdev_handle *bdev_open_by_dev(dev_t dev, blk_mode_t mode, void *holder,
+				     const struct blk_holder_ops *hops)
+{
+	struct bdev_handle *handle = kmalloc(sizeof(*handle), GFP_KERNEL);
+	struct block_device *bdev;
+
+	if (!handle)
+		return ERR_PTR(-ENOMEM);
+	bdev = blkdev_get_by_dev(dev, mode, holder, hops);
+	if (IS_ERR(bdev)) {
+		kfree(handle);
+		return ERR_CAST(bdev);
+	}
+	handle->bdev = bdev;
+	handle->holder = holder;
+	if (holder)
+		mode |= BLK_OPEN_EXCL;
+	handle->mode = mode;
+	return handle;
+}
+EXPORT_SYMBOL(bdev_open_by_dev);
+
 /**
  * blkdev_get_by_path - open a block device by name
  * @path: path to the block device to open
@@ -867,6 +889,28 @@ struct block_device *blkdev_get_by_path(const char *path, blk_mode_t mode,
 }
 EXPORT_SYMBOL(blkdev_get_by_path);
 
+struct bdev_handle *bdev_open_by_path(const char *path, blk_mode_t mode,
+		void *holder, const struct blk_holder_ops *hops)
+{
+	struct bdev_handle *handle;
+	dev_t dev;
+	int error;
+
+	error = lookup_bdev(path, &dev);
+	if (error)
+		return ERR_PTR(error);
+
+	handle = bdev_open_by_dev(dev, mode, holder, hops);
+	if (!IS_ERR(handle) && (mode & BLK_OPEN_WRITE) &&
+	    bdev_read_only(handle->bdev)) {
+		bdev_release(handle);
+		return ERR_PTR(-EACCES);
+	}
+
+	return handle;
+}
+EXPORT_SYMBOL(bdev_open_by_path);
+
 void blkdev_put(struct block_device *bdev, void *holder)
 {
 	struct gendisk *disk = bdev->bd_disk;
@@ -903,6 +947,13 @@ void blkdev_put(struct block_device *bdev, void *holder)
 }
 EXPORT_SYMBOL(blkdev_put);
 
+void bdev_release(struct bdev_handle *handle)
+{
+	blkdev_put(handle->bdev, handle->holder);
+	kfree(handle);
+}
+EXPORT_SYMBOL(bdev_release);
+
 /**
  * lookup_bdev() - Look up a struct block_device by name.
  * @pathname: Name of the block device in the filesystem.
@@ -961,20 +1012,20 @@ void bdev_mark_dead(struct block_device *bdev, bool surprise)
 	mutex_lock(&bdev->bd_holder_lock);
 	if (bdev->bd_holder_ops && bdev->bd_holder_ops->mark_dead)
 		bdev->bd_holder_ops->mark_dead(bdev, surprise);
-	else
+	else {
+		mutex_unlock(&bdev->bd_holder_lock);
 		sync_blockdev(bdev);
-	mutex_unlock(&bdev->bd_holder_lock);
+	}
 
 	invalidate_bdev(bdev);
 }
-#ifdef CONFIG_DASD_MODULE
 /*
- * Drivers should not use this directly, but the DASD driver has historically
- * had a shutdown to offline mode that doesn't actually remove the gendisk
- * that otherwise looks a lot like a safe device removal.
+ * New drivers should not use this directly.  There are some drivers however
+ * that needs this for historical reasons. For example, the DASD driver has
+ * historically had a shutdown to offline mode that doesn't actually remove the
+ * gendisk that otherwise looks a lot like a safe device removal.
  */
 EXPORT_SYMBOL_GPL(bdev_mark_dead);
-#endif
 
 void sync_bdevs(bool wait)
 {