Merge git://git.kvack.org/~bcrl/aio-fixes

Pull aio bugfixes from Ben LaHaise:
 "Two small fixes"

* git://git.kvack.org/~bcrl/aio-fixes:
  aio: block exit_aio() until all context requests are completed
  aio: add missing smp_rmb() in read_events_ring

fs/aio.c

@@ -793,6 +793,8 @@ void exit_aio(struct mm_struct *mm)
 
 	for (i = 0; i < table->nr; ++i) {
 		struct kioctx *ctx = table->table[i];
+		struct completion requests_done =
+			COMPLETION_INITIALIZER_ONSTACK(requests_done);
 
 		if (!ctx)
 			continue;
@@ -804,7 +806,10 @@ void exit_aio(struct mm_struct *mm)
 		 * that it needs to unmap the area, just set it to 0.
 		 */
 		ctx->mmap_size = 0;
-		kill_ioctx(mm, ctx, NULL);
+		kill_ioctx(mm, ctx, &requests_done);
+
+		/* Wait until all IO for the context are done. */
+		wait_for_completion(&requests_done);
 	}
 
 	RCU_INIT_POINTER(mm->ioctx_table, NULL);
@@ -1111,6 +1116,12 @@ static long aio_read_events_ring(struct kioctx *ctx,
 	tail = ring->tail;
 	kunmap_atomic(ring);
 
+	/*
+	 * Ensure that once we've read the current tail pointer, that
+	 * we also see the events that were stored up to the tail.
+	 */
+	smp_rmb();
+
 	pr_debug("h%u t%u m%u\n", head, tail, ctx->nr_events);
 
 	if (head == tail)