ext4: export iov_shorten from kernel for ext4's use

Export iov_shorten() from kernel so that ext4 can
truncate too-large writes to bitmapped files.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
diff --git a/fs/read_write.c b/fs/read_write.c
index c4d3d17..1c177f2 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -446,6 +446,7 @@
 	}
 	return seg;
 }
+EXPORT_SYMBOL(iov_shorten);
 
 ssize_t do_sync_readv_writev(struct file *filp, const struct iovec *iov,
 		unsigned long nr_segs, size_t len, loff_t *ppos, iov_fn_t fn)