From patchwork Mon Nov 25 14:37:03 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johannes Thumshirn X-Patchwork-Id: 11260491 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D342017F0 for ; Mon, 25 Nov 2019 14:37:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BE188207FD for ; Mon, 25 Nov 2019 14:37:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728195AbfKYOhO (ORCPT ); Mon, 25 Nov 2019 09:37:14 -0500 Received: from mx2.suse.de ([195.135.220.15]:37856 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728187AbfKYOhO (ORCPT ); Mon, 25 Nov 2019 09:37:14 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 75610B4B5; Mon, 25 Nov 2019 14:37:12 +0000 (UTC) From: Johannes Thumshirn To: David Sterba Cc: Nikolay Borisov , Qu Wenruo , Linux BTRFS Mailinglist , Johannes Thumshirn Subject: [PATCH v3 2/2] btrfs: reset device back to allocation state when removing Date: Mon, 25 Nov 2019 15:37:03 +0100 Message-Id: <20191125143703.4989-3-jthumshirn@suse.de> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20191125143703.4989-1-jthumshirn@suse.de> References: <20191125143703.4989-1-jthumshirn@suse.de> Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org When closing a device, btrfs_close_one_device() first allocates a new device, copies the device to close's name, replaces it in the dev_list with the copy and then finally frees it. This involves two memory allocation, which can potentially fail. As this code path is tricky to unwind, the allocation failures where handled by BUG_ON()s. But this copying isn't strictly needed, all that is needed is resetting the device in question to it's state it had after the allocation. Signed-off-by: Johannes Thumshirn --- fs/btrfs/volumes.c | 34 +++++++++++++++------------------- 1 file changed, 15 insertions(+), 19 deletions(-) diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 2398b071bcf6..3d04fa4a0ba6 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1064,38 +1064,34 @@ static void btrfs_close_bdev(struct btrfs_device *device) static void btrfs_close_one_device(struct btrfs_device *device) { struct btrfs_fs_devices *fs_devices = device->fs_devices; - struct btrfs_device *new_device; - struct rcu_string *name; if (test_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state) && device->devid != BTRFS_DEV_REPLACE_DEVID) { list_del_init(&device->dev_alloc_list); fs_devices->rw_devices--; } + clear_bit(BTRFS_DEV_STATE_WRITEABLE, &device->dev_state); - if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) + if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) { fs_devices->missing_devices--; + clear_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state); + } + clear_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state); btrfs_close_bdev(device); - if (device->bdev) + if (device->bdev) { fs_devices->open_devices--; - - new_device = btrfs_alloc_device(NULL, &device->devid, - device->uuid); - BUG_ON(IS_ERR(new_device)); /* -ENOMEM */ - - /* Safe because we are under uuid_mutex */ - if (device->name) { - name = rcu_string_strdup(device->name->str, GFP_NOFS); - BUG_ON(!name); /* -ENOMEM */ - rcu_assign_pointer(new_device->name, name); + device->bdev = NULL; } - list_replace_rcu(&device->dev_list, &new_device->dev_list); - new_device->fs_devices = device->fs_devices; - - synchronize_rcu(); - btrfs_free_device(device); + /* Verify the device is back in a pristine state */ + ASSERT(!test_bit(BTRFS_DEV_STATE_FLUSH_SENT, &device->dev_state)); + ASSERT(!test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)); + ASSERT(list_empty(&device->dev_alloc_list)); + ASSERT(list_empty(&device->post_commit_list)); + ASSERT(atomic_read(&device->reada_in_flight) == 0); + ASSERT(atomic_read(&device->dev_stats_ccnt) == 0); + ASSERT(RB_EMPTY_ROOT(&device->alloc_state.state)); } static int close_fs_devices(struct btrfs_fs_devices *fs_devices)