2 files changed, 15 insertions, 6 deletions

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 160a5489a939..a701752dd750 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -1194,13 +1194,19 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
         }
 
         /*
-         * For file extending writes updating i_size before data
-         * writeouts complete can expose uninitialized blocks. So
-         * even for AIO, we need to wait for i/o to complete before
-         * returning in this case.
+         * For file extending writes updating i_size before data writeouts
+         * complete can expose uninitialized blocks in dumb filesystems.
+         * In that case we need to wait for I/O completion even if asked
+         * for an asynchronous write.
          */
-        dio->is_async = !is_sync_kiocb(iocb) && !((rw & WRITE) &&
-                (end > i_size_read(inode)));
+        if (is_sync_kiocb(iocb))
+                dio->is_async = false;
+        else if (!(dio->flags & DIO_ASYNC_EXTEND) &&
+            (rw & WRITE) && end > i_size_read(inode))
+                dio->is_async = false;
+        else
+                dio->is_async = true;
+
         dio->inode = inode;
         dio->rw = rw;
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 09f553c59813..f7faefcf4843 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2527,6 +2527,9 @@ enum {
 
         /* filesystem does not support filling holes */
         DIO_SKIP_HOLES  = 0x02,
+
+        /* filesystem can handle aio writes beyond i_size */
+        DIO_ASYNC_EXTEND = 0x04,
 };
 
 void dio_end_io(struct bio *bio, int error);