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

Pull aio fix and cleanups from Ben LaHaise:
 "This consists of a couple of code cleanups plus a minor bug fix"

* git://git.kvack.org/~bcrl/aio-next:
  aio: cleanup: flatten kill_ioctx()
  aio: report error from io_destroy() when threads race in io_destroy()
  fs/aio.c: Remove ctx parameter in kiocb_cancel

fs/aio.c

@@ -477,7 +477,7 @@ void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel)
 }
 EXPORT_SYMBOL(kiocb_set_cancel_fn);
 
-static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb)
+static int kiocb_cancel(struct kiocb *kiocb)
 {
 	kiocb_cancel_fn *old, *cancel;
 
@@ -538,7 +538,7 @@ static void free_ioctx_users(struct percpu_ref *ref)
 				       struct kiocb, ki_list);
 
 		list_del_init(&req->ki_list);
-		kiocb_cancel(ctx, req);
+		kiocb_cancel(req);
 	}
 
 	spin_unlock_irq(&ctx->ctx_lock);
@@ -727,42 +727,42 @@ static struct kioctx *ioctx_alloc(unsigned nr_events)
  *	when the processes owning a context have all exited to encourage
  *	the rapid destruction of the kioctx.
  */
-static void kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
+static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
 		struct completion *requests_done)
 {
-	if (!atomic_xchg(&ctx->dead, 1)) {
-		struct kioctx_table *table;
+	struct kioctx_table *table;
 
-		spin_lock(&mm->ioctx_lock);
-		rcu_read_lock();
-		table = rcu_dereference(mm->ioctx_table);
+	if (atomic_xchg(&ctx->dead, 1))
+		return -EINVAL;
 
-		WARN_ON(ctx != table->table[ctx->id]);
-		table->table[ctx->id] = NULL;
-		rcu_read_unlock();
-		spin_unlock(&mm->ioctx_lock);
 
-		/* percpu_ref_kill() will do the necessary call_rcu() */
-		wake_up_all(&ctx->wait);
+	spin_lock(&mm->ioctx_lock);
+	rcu_read_lock();
+	table = rcu_dereference(mm->ioctx_table);
 
-		/*
-		 * It'd be more correct to do this in free_ioctx(), after all
-		 * the outstanding kiocbs have finished - but by then io_destroy
-		 * has already returned, so io_setup() could potentially return
-		 * -EAGAIN with no ioctxs actually in use (as far as userspace
-		 *  could tell).
-		 */
-		aio_nr_sub(ctx->max_reqs);
+	WARN_ON(ctx != table->table[ctx->id]);
+	table->table[ctx->id] = NULL;
+	rcu_read_unlock();
+	spin_unlock(&mm->ioctx_lock);
 
-		if (ctx->mmap_size)
-			vm_munmap(ctx->mmap_base, ctx->mmap_size);
+	/* percpu_ref_kill() will do the necessary call_rcu() */
+	wake_up_all(&ctx->wait);
 
-		ctx->requests_done = requests_done;
-		percpu_ref_kill(&ctx->users);
-	} else {
-		if (requests_done)
-			complete(requests_done);
-	}
+	/*
+	 * It'd be more correct to do this in free_ioctx(), after all
+	 * the outstanding kiocbs have finished - but by then io_destroy
+	 * has already returned, so io_setup() could potentially return
+	 * -EAGAIN with no ioctxs actually in use (as far as userspace
+	 *  could tell).
+	 */
+	aio_nr_sub(ctx->max_reqs);
+
+	if (ctx->mmap_size)
+		vm_munmap(ctx->mmap_base, ctx->mmap_size);
+
+	ctx->requests_done = requests_done;
+	percpu_ref_kill(&ctx->users);
+	return 0;
 }
 
 /* wait_on_sync_kiocb:
@@ -1219,21 +1219,23 @@ SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
 	if (likely(NULL != ioctx)) {
 		struct completion requests_done =
 			COMPLETION_INITIALIZER_ONSTACK(requests_done);
+		int ret;
 
 		/* Pass requests_done to kill_ioctx() where it can be set
 		 * in a thread-safe way. If we try to set it here then we have
 		 * a race condition if two io_destroy() called simultaneously.
 		 */
-		kill_ioctx(current->mm, ioctx, &requests_done);
+		ret = kill_ioctx(current->mm, ioctx, &requests_done);
 		percpu_ref_put(&ioctx->users);
 
 		/* Wait until all IO for the context are done. Otherwise kernel
 		 * keep using user-space buffers even if user thinks the context
 		 * is destroyed.
 		 */
-		wait_for_completion(&requests_done);
+		if (!ret)
+			wait_for_completion(&requests_done);
 
-		return 0;
+		return ret;
 	}
 	pr_debug("EINVAL: io_destroy: invalid context id\n");
 	return -EINVAL;
@@ -1595,7 +1597,7 @@ SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,
 
 	kiocb = lookup_kiocb(ctx, iocb, key);
 	if (kiocb)
-		ret = kiocb_cancel(ctx, kiocb);
+		ret = kiocb_cancel(kiocb);
 	else
 		ret = -EINVAL;