From patchwork Fri Sep 7 14:55:02 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Sterba X-Patchwork-Id: 10592243 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 5F8B413AC for ; Fri, 7 Sep 2018 14:55:21 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 426942B55A for ; Fri, 7 Sep 2018 14:55:21 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 368A22B567; Fri, 7 Sep 2018 14:55:21 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CF59B2B55A for ; Fri, 7 Sep 2018 14:55:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730018AbeIGTgg (ORCPT ); Fri, 7 Sep 2018 15:36:36 -0400 Received: from mx2.suse.de ([195.135.220.15]:50554 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728823AbeIGTgg (ORCPT ); Fri, 7 Sep 2018 15:36:36 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 28418AC1F for ; Fri, 7 Sep 2018 14:55:18 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 35CB0DAD81; Fri, 7 Sep 2018 16:55:02 +0200 (CEST) From: David Sterba To: linux-btrfs@vger.kernel.org Cc: David Sterba Subject: [PATCH 01/11] btrfs: remove btrfs_dev_replace::read_locks Date: Fri, 7 Sep 2018 16:55:02 +0200 Message-Id: <8787a706839a04a736f389d9d24ab215f15467d5.1536331604.git.dsterba@suse.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: References: Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This member seems to be copied from the extent_buffer locking scheme and is at least used to assert that the read lock/unlock is properly nested. In some way. While the _inc/_dec are called inside the read lock section, the asserts are both inside and outside, so the ordering is not guaranteed and we can see read/inc/dec ordered in any way (theoretically). A missing call of btrfs_dev_replace_clear_lock_blocking could cause unexpected read_locks count, so this at least looks like a valid assertion, but this will become unnecessary with later updates. Signed-off-by: David Sterba --- fs/btrfs/ctree.h | 1 - fs/btrfs/dev-replace.c | 5 ----- fs/btrfs/disk-io.c | 1 - 3 files changed, 7 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 441610de9908..31f7a58add7e 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -367,7 +367,6 @@ struct btrfs_dev_replace { struct mutex lock_finishing_cancel_unmount; rwlock_t lock; - atomic_t read_locks; atomic_t blocking_readers; wait_queue_head_t read_lock_wq; diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c index dec01970d8c5..24529d2c723a 100644 --- a/fs/btrfs/dev-replace.c +++ b/fs/btrfs/dev-replace.c @@ -961,13 +961,10 @@ int btrfs_dev_replace_is_ongoing(struct btrfs_dev_replace *dev_replace) void btrfs_dev_replace_read_lock(struct btrfs_dev_replace *dev_replace) { read_lock(&dev_replace->lock); - atomic_inc(&dev_replace->read_locks); } void btrfs_dev_replace_read_unlock(struct btrfs_dev_replace *dev_replace) { - ASSERT(atomic_read(&dev_replace->read_locks) > 0); - atomic_dec(&dev_replace->read_locks); read_unlock(&dev_replace->lock); } @@ -994,7 +991,6 @@ void btrfs_dev_replace_set_lock_blocking( struct btrfs_dev_replace *dev_replace) { /* only set blocking for read lock */ - ASSERT(atomic_read(&dev_replace->read_locks) > 0); atomic_inc(&dev_replace->blocking_readers); read_unlock(&dev_replace->lock); } @@ -1004,7 +1000,6 @@ void btrfs_dev_replace_clear_lock_blocking( struct btrfs_dev_replace *dev_replace) { /* only set blocking for read lock */ - ASSERT(atomic_read(&dev_replace->read_locks) > 0); ASSERT(atomic_read(&dev_replace->blocking_readers) > 0); read_lock(&dev_replace->lock); /* Barrier implied by atomic_dec_and_test */ diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 3611df2ce5c1..acd0cbc5a6b9 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2155,7 +2155,6 @@ static void btrfs_init_dev_replace_locks(struct btrfs_fs_info *fs_info) { mutex_init(&fs_info->dev_replace.lock_finishing_cancel_unmount); rwlock_init(&fs_info->dev_replace.lock); - atomic_set(&fs_info->dev_replace.read_locks, 0); atomic_set(&fs_info->dev_replace.blocking_readers, 0); init_waitqueue_head(&fs_info->replace_wait); init_waitqueue_head(&fs_info->dev_replace.read_lock_wq);