[PATCH] aio-retry-fix: fix aio retry work queueing

In the case of buffered AIO, in the aio retry path (aio_run_iocb), when the
retry method returns EIOCBRETRY the kicked iocb is added to the context run
list but is never queued onto the work queue.  The request therefore is
never completed.

This patch fixes that by adding the appropriate call to aio_queue_work in
aio_run_aiocb so that subsequent retries will be handled by the aio worker
thread.

Signed-off-by: Sébastien Dugué <sebastien.dugue@bull.net>
Acked-by: Benjamin LaHaise <benjamin.c.lahaise@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/aio.c

@@ -58,6 +58,7 @@ static DEFINE_SPINLOCK(fput_lock);
 static LIST_HEAD(fput_head);
 
 static void aio_kick_handler(void *);
+static void aio_queue_work(struct kioctx *);
 
 /* aio_setup
  *	Creates the slab caches used by the aio routines, panic on
@@ -747,6 +748,14 @@ static ssize_t aio_run_iocb(struct kiocb *iocb)
 		 * has already been kicked */
 		if (kiocbIsKicked(iocb)) {
 			__queue_kicked_iocb(iocb);
+
+			/*
+			 * __queue_kicked_iocb will always return 1 here, because
+			 * iocb->ki_run_list is empty at this point so it should
+			 * be safe to unconditionally queue the context into the
+			 * work queue.
+			 */
+			aio_queue_work(ctx);
 		}
 	}
 	return ret;