From patchwork Sun Oct 11 17:50:37 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Sterba X-Patchwork-Id: 7369451 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id D1574BEEA4 for ; Sun, 11 Oct 2015 17:51:53 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id DB3D6206CD for ; Sun, 11 Oct 2015 17:51:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CFFFF206CC for ; Sun, 11 Oct 2015 17:51:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752066AbbJKRvr (ORCPT ); Sun, 11 Oct 2015 13:51:47 -0400 Received: from mx2.suse.de ([195.135.220.15]:37056 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751679AbbJKRvq (ORCPT ); Sun, 11 Oct 2015 13:51:46 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id AA123AC66 for ; Sun, 11 Oct 2015 17:51:43 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 57CD9DAB45; Sun, 11 Oct 2015 19:50:37 +0200 (CEST) From: David Sterba To: linux-btrfs@vger.kernel.org Cc: David Sterba Subject: [PATCH 6/6] btrfs: comment the rest of implicit barriers before waitqueue_active Date: Sun, 11 Oct 2015 19:50:37 +0200 Message-Id: X-Mailer: git-send-email 2.1.3 In-Reply-To: References: Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP There are atomic operations that imply the barrier for waitqueue_active mixed in an if-condition. Signed-off-by: David Sterba --- fs/btrfs/delayed-inode.c | 4 ++++ fs/btrfs/disk-io.c | 3 +++ fs/btrfs/inode.c | 3 +++ fs/btrfs/locking.c | 9 +++++++++ fs/btrfs/volumes.c | 3 +++ 5 files changed, 22 insertions(+) diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c index a2ae42720a6a..e0941fbb913c 100644 --- a/fs/btrfs/delayed-inode.c +++ b/fs/btrfs/delayed-inode.c @@ -463,6 +463,10 @@ static int __btrfs_add_delayed_deletion_item(struct btrfs_delayed_node *node, static void finish_one_item(struct btrfs_delayed_root *delayed_root) { int seq = atomic_inc_return(&delayed_root->items_seq); + + /* + * atomic_dec_return implies a barrier for waitqueue_active + */ if ((atomic_dec_return(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND || seq % BTRFS_DELAYED_BATCH == 0) && waitqueue_active(&delayed_root->wait)) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 295795aebe0b..379526ffd84d 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -802,6 +802,9 @@ static void run_one_async_done(struct btrfs_work *work) limit = btrfs_async_submit_limit(fs_info); limit = limit * 2 / 3; + /* + * atomic_dec_return implies a barrier for waitqueue_active + */ if (atomic_dec_return(&fs_info->nr_async_submits) < limit && waitqueue_active(&fs_info->async_submit_wait)) wake_up(&fs_info->async_submit_wait); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 611b66d73e80..7be4abe25e06 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1096,6 +1096,9 @@ static noinline void async_cow_submit(struct btrfs_work *work) nr_pages = (async_cow->end - async_cow->start + PAGE_CACHE_SIZE) >> PAGE_CACHE_SHIFT; + /* + * atomic_sub_return implies a barrier for waitqueue_active + */ if (atomic_sub_return(nr_pages, &root->fs_info->async_delalloc_pages) < 5 * 1024 * 1024 && waitqueue_active(&root->fs_info->async_submit_wait)) diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 03f8630dbaf2..8077461fc56a 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -79,6 +79,9 @@ void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw) write_lock(&eb->lock); WARN_ON(atomic_read(&eb->spinning_writers)); atomic_inc(&eb->spinning_writers); + /* + * atomic_dec_and_test implies a barrier for waitqueue_active + */ if (atomic_dec_and_test(&eb->blocking_writers) && waitqueue_active(&eb->write_lock_wq)) wake_up(&eb->write_lock_wq); @@ -86,6 +89,9 @@ void btrfs_clear_lock_blocking_rw(struct extent_buffer *eb, int rw) BUG_ON(atomic_read(&eb->blocking_readers) == 0); read_lock(&eb->lock); atomic_inc(&eb->spinning_readers); + /* + * atomic_dec_and_test implies a barrier for waitqueue_active + */ if (atomic_dec_and_test(&eb->blocking_readers) && waitqueue_active(&eb->read_lock_wq)) wake_up(&eb->read_lock_wq); @@ -229,6 +235,9 @@ void btrfs_tree_read_unlock_blocking(struct extent_buffer *eb) } btrfs_assert_tree_read_locked(eb); WARN_ON(atomic_read(&eb->blocking_readers) == 0); + /* + * atomic_dec_and_test implies a barrier for waitqueue_active + */ if (atomic_dec_and_test(&eb->blocking_readers) && waitqueue_active(&eb->read_lock_wq)) wake_up(&eb->read_lock_wq); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 6fc735869c18..ff3527192409 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -345,6 +345,9 @@ static noinline void run_scheduled_bios(struct btrfs_device *device) pending = pending->bi_next; cur->bi_next = NULL; + /* + * atomic_dec_return implies a barrier for waitqueue_active + */ if (atomic_dec_return(&fs_info->nr_async_bios) < limit && waitqueue_active(&fs_info->async_submit_wait)) wake_up(&fs_info->async_submit_wait);