+/*
+ * Drop all buffers & page cache for given bdev range. This function bails
+ * with error if bdev has other exclusive owner (such as filesystem).
+ */
+int truncate_bdev_range(struct block_device *bdev, fmode_t mode,
+ loff_t lstart, loff_t lend)
+{
+ struct block_device *claimed_bdev = NULL;
+ int err;
+
+ /*
+ * If we don't hold exclusive handle for the device, upgrade to it
+ * while we discard the buffer cache to avoid discarding buffers
+ * under live filesystem.
+ */
+ if (!(mode & FMODE_EXCL)) {
+ claimed_bdev = bdev->bd_contains;
+ err = bd_prepare_to_claim(bdev, claimed_bdev,
+ truncate_bdev_range);
+ if (err)
+ return err;
+ }
+ truncate_inode_pages_range(bdev->bd_inode->i_mapping, lstart, lend);
+ if (claimed_bdev)
+ bd_abort_claiming(bdev, claimed_bdev, truncate_bdev_range);
+ return 0;
+}
+EXPORT_SYMBOL(truncate_bdev_range);
+