From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C462C433E9 for ; Wed, 10 Feb 2021 12:57:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2FD3464E7A for ; Wed, 10 Feb 2021 12:57:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231583AbhBJM5o (ORCPT ); Wed, 10 Feb 2021 07:57:44 -0500 Received: from mx2.suse.de ([195.135.220.15]:55716 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230450AbhBJM4P (ORCPT ); Wed, 10 Feb 2021 07:56:15 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id B3FDDAEB9; Wed, 10 Feb 2021 12:55:31 +0000 (UTC) Date: Wed, 10 Feb 2021 12:55:30 +0000 From: Michal Rostecki To: Filipe Manana Cc: Chris Mason , Josef Bacik , David Sterba , "open list:BTRFS FILE SYSTEM" , open list , Michal Rostecki Subject: Re: [PATCH RFC 4/6] btrfs: Check if the filesystem is has mixed type of devices Message-ID: <20210210125530.GD23499@wotan.suse.de> References: <20210209203041.21493-1-mrostecki@suse.de> <20210209203041.21493-5-mrostecki@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Wed, Feb 10, 2021 at 10:09:10AM +0000, Filipe Manana wrote: > On Tue, Feb 9, 2021 at 9:32 PM Michal Rostecki wrote: > > > > From: Michal Rostecki > > > > Add the btrfs_check_mixed() function which checks if the filesystem has > > the mixed type of devices (non-rotational and rotational). This > > information is going to be used in roundrobin raid1 read policy. > > > > Signed-off-by: Michal Rostecki > > --- > > fs/btrfs/volumes.c | 44 ++++++++++++++++++++++++++++++++++++++++++-- > > fs/btrfs/volumes.h | 7 +++++++ > > 2 files changed, 49 insertions(+), 2 deletions(-) > > > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > > index 1ac364a2f105..1ad30a595722 100644 > > --- a/fs/btrfs/volumes.c > > +++ b/fs/btrfs/volumes.c > > @@ -617,6 +617,35 @@ static int btrfs_free_stale_devices(const char *path, > > return ret; > > } > > > > +/* > > + * Checks if after adding the new device the filesystem is going to have mixed > > + * types of devices (non-rotational and rotational). > > + * > > + * @fs_devices: list of devices > > + * @new_device_rotating: if the new device is rotational > > + * > > + * Returns true if there are mixed types of devices, otherwise returns false. > > + */ > > +static bool btrfs_check_mixed(struct btrfs_fs_devices *fs_devices, > > + bool new_device_rotating) > > +{ > > + struct btrfs_device *device, *prev_device; > > + > > + list_for_each_entry(device, &fs_devices->devices, dev_list) { > > + if (prev_device == NULL && > > Hum, prev_device is not initialized when we enter the first iteration > of the loop. > > > + device->rotating != new_device_rotating) > > + return true; > > + if (prev_device != NULL && > > + (device->rotating != prev_device->rotating || > > Here it's more dangerous, dereferencing an uninitialized pointer can > result in a crash. > > With this fixed, it would be better to redo the benchmarks when using > mixed device types. > > Thanks. > Thanks for pointing that out. Will fix and redo benchmarks for v2. > > + device->rotating != new_device_rotating)) > > + return true; > > + > > + prev_device = device; > > + } > > + > > + return false; > > +} > > + > > /* > > * This is only used on mount, and we are protected from competing things > > * messing with our fs_devices by the uuid_mutex, thus we do not need the > > @@ -629,6 +658,7 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices, > > struct request_queue *q; > > struct block_device *bdev; > > struct btrfs_super_block *disk_super; > > + bool rotating; > > u64 devid; > > int ret; > > > > @@ -669,8 +699,12 @@ static int btrfs_open_one_device(struct btrfs_fs_devices *fs_devices, > > } > > > > q = bdev_get_queue(bdev); > > - if (!blk_queue_nonrot(q)) > > + rotating = !blk_queue_nonrot(q); > > + device->rotating = rotating; > > + if (rotating) > > fs_devices->rotating = true; > > + if (!fs_devices->mixed) > > + fs_devices->mixed = btrfs_check_mixed(fs_devices, rotating); > > > > device->bdev = bdev; > > clear_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state); > > @@ -2418,6 +2452,7 @@ static int btrfs_prepare_sprout(struct btrfs_fs_info *fs_info) > > fs_devices->open_devices = 0; > > fs_devices->missing_devices = 0; > > fs_devices->rotating = false; > > + fs_devices->mixed = false; > > list_add(&seed_devices->seed_list, &fs_devices->seed_list); > > > > generate_random_uuid(fs_devices->fsid); > > @@ -2522,6 +2557,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path > > int seeding_dev = 0; > > int ret = 0; > > bool locked = false; > > + bool rotating; > > > > if (sb_rdonly(sb) && !fs_devices->seeding) > > return -EROFS; > > @@ -2621,8 +2657,12 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path > > > > atomic64_add(device->total_bytes, &fs_info->free_chunk_space); > > > > - if (!blk_queue_nonrot(q)) > > + rotating = !blk_queue_nonrot(q); > > + device->rotating = rotating; > > + if (rotating) > > fs_devices->rotating = true; > > + if (!fs_devices->mixed) > > + fs_devices->mixed = btrfs_check_mixed(fs_devices, rotating); > > > > orig_super_total_bytes = btrfs_super_total_bytes(fs_info->super_copy); > > btrfs_set_super_total_bytes(fs_info->super_copy, > > diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h > > index 6e544317a377..594f1207281c 100644 > > --- a/fs/btrfs/volumes.h > > +++ b/fs/btrfs/volumes.h > > @@ -147,6 +147,9 @@ struct btrfs_device { > > /* I/O stats for raid1 mirror selection */ > > struct percpu_counter inflight; > > atomic_t last_offset; > > + > > + /* If the device is rotational */ > > + bool rotating; > > }; > > > > /* > > @@ -274,6 +277,10 @@ struct btrfs_fs_devices { > > * nonrot flag set > > */ > > bool rotating; > > + /* Set when we find or add both nonrot and rot disks in the > > + * filesystem > > + */ > > + bool mixed; > > > > struct btrfs_fs_info *fs_info; > > /* sysfs kobjects */ > > -- > > 2.30.0 > > > > > -- > Filipe David Manana, > > “Whether you think you can, or you think you can't — you're right.”