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Mon, 31 Aug 2020 12:00:35 +0000 Received: from pps.filterd (aserp3020.oracle.com [127.0.0.1]) by aserp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 07VBuYYU088562; Mon, 31 Aug 2020 12:00:34 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by aserp3020.oracle.com with ESMTP id 3380x02xfw-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 31 Aug 2020 12:00:34 +0000 Received: from abhmp0020.oracle.com (abhmp0020.oracle.com [141.146.116.26]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 07VC0V4W011203; Mon, 31 Aug 2020 12:00:33 GMT Received: from [192.168.1.102] (/39.109.231.106) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 31 Aug 2020 05:00:31 -0700 Subject: Re: [PATCH 01/11] btrfs: initialize sysfs devid and device link for seed device To: Nikolay Borisov , linux-btrfs@vger.kernel.org Cc: dsterba@suse.com, josef@toxicpanda.com References: <2db650ec206db1cb3e68590951b59e222fb10116.1598792561.git.anand.jain@oracle.com> From: Anand Jain Message-ID: <2c60ae0b-8bff-2611-f737-be731b185b93@oracle.com> Date: Mon, 31 Aug 2020 20:00:22 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9729 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 spamscore=0 phishscore=0 mlxlogscore=999 adultscore=0 suspectscore=0 bulkscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008310069 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9729 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 bulkscore=0 adultscore=0 mlxscore=0 lowpriorityscore=0 phishscore=0 clxscore=1015 suspectscore=0 priorityscore=1501 spamscore=0 malwarescore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008310069 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 31/8/20 5:07 pm, Nikolay Borisov wrote: > > > On 30.08.20 г. 17:40 ч., Anand Jain wrote: >> The following test case leads to null kobject-being-freed error. >> >> mount seed /mnt >> add sprout to /mnt >> umount /mnt >> mount sprout to /mnt >> delete seed >> >> kobject: '(null)' (00000000dd2b87e4): is not initialized, yet kobject_put() is being called. >> WARNING: CPU: 1 PID: 15784 at lib/kobject.c:736 kobject_put+0x80/0x350 >> RIP: 0010:kobject_put+0x80/0x350 >> :: >> Call Trace: >> btrfs_sysfs_remove_devices_dir+0x6e/0x160 [btrfs] >> btrfs_rm_device.cold+0xa8/0x298 [btrfs] >> btrfs_ioctl+0x206c/0x22a0 [btrfs] >> ksys_ioctl+0xe2/0x140 >> __x64_sys_ioctl+0x1e/0x29 >> do_syscall_64+0x96/0x150 >> entry_SYSCALL_64_after_hwframe+0x44/0xa9 >> RIP: 0033:0x7f4047c6288b >> :: >> >> This is because, at the end of the seed device-delete, we try to remove >> the seed's devid sysfs entry. But for the seed devices under the sprout >> fs, we don't initialize the devid kobject yet. So this patch initializes >> the seed device devid kobject and the device link in the sysfs. This takes >> care of the Warning. >> >> Signed-off-by: Anand Jain > > This patch is doing too many things at once. Split it so that: > 1. You first add the new functions add_device/remove_device in 2 > separate patches. > 2. Switch btrfs_sysfs_add_devices_dir/btrfs_sysfs_remove_devices_dir to > ousing the newly added helpers, again in 2 separate patches yeah and 3. Initialize seed devices devid kobject to fix the bug. fixing. -Anand > >> --- >> fs/btrfs/sysfs.c | 146 ++++++++++++++++++++++++++++++----------------- >> 1 file changed, 93 insertions(+), 53 deletions(-) >> >> diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c >> index 190e59152be5..9b5e58091fae 100644 >> --- a/fs/btrfs/sysfs.c >> +++ b/fs/btrfs/sysfs.c >> @@ -1149,45 +1149,48 @@ int btrfs_sysfs_add_space_info_type(struct btrfs_fs_info *fs_info, >> return 0; >> } >> >> -/* when one_device is NULL, it removes all device links */ >> - >> -int btrfs_sysfs_remove_devices_dir(struct btrfs_fs_devices *fs_devices, >> - struct btrfs_device *one_device) >> +static void btrfs_sysfs_remove_device(struct btrfs_device *device) >> { >> struct hd_struct *disk; >> struct kobject *disk_kobj; >> + struct kobject *devices_kobj; >> >> - if (!fs_devices->devices_kobj) >> - return -EINVAL; >> + /* >> + * Seed fs_devices devices_kobj aren't used, fetch kobject from the >> + * fs_info::fs_devices. >> + */ >> + devices_kobj = device->fs_info->fs_devices->devices_kobj; >> + ASSERT(devices_kobj); >> >> - if (one_device) { >> - if (one_device->bdev) { >> - disk = one_device->bdev->bd_part; >> - disk_kobj = &part_to_dev(disk)->kobj; >> - sysfs_remove_link(fs_devices->devices_kobj, >> - disk_kobj->name); >> - } >> + if (device->bdev) { >> + disk = device->bdev->bd_part; >> + disk_kobj = &part_to_dev(disk)->kobj; >> + sysfs_remove_link(devices_kobj, disk_kobj->name); >> + } >> >> - kobject_del(&one_device->devid_kobj); >> - kobject_put(&one_device->devid_kobj); >> + kobject_del(&device->devid_kobj); >> + kobject_put(&device->devid_kobj); >> >> - wait_for_completion(&one_device->kobj_unregister); >> + wait_for_completion(&device->kobj_unregister); >> +} >> >> +/* when 2nd argument device is NULL, it removes all devices link */ >> +int btrfs_sysfs_remove_devices_dir(struct btrfs_fs_devices *fs_devices, >> + struct btrfs_device *device) >> +{ >> + struct btrfs_fs_devices *seed_fs_devices; >> + >> + if (device) { >> + btrfs_sysfs_remove_device(device); >> return 0; >> } >> >> - list_for_each_entry(one_device, &fs_devices->devices, dev_list) { >> - >> - if (one_device->bdev) { >> - disk = one_device->bdev->bd_part; >> - disk_kobj = &part_to_dev(disk)->kobj; >> - sysfs_remove_link(fs_devices->devices_kobj, >> - disk_kobj->name); >> - } >> - kobject_del(&one_device->devid_kobj); >> - kobject_put(&one_device->devid_kobj); >> + list_for_each_entry(device, &fs_devices->devices, dev_list) >> + btrfs_sysfs_remove_device(device); >> >> - wait_for_completion(&one_device->kobj_unregister); >> + list_for_each_entry(seed_fs_devices, &fs_devices->seed_list, seed_list) { >> + list_for_each_entry(device, &seed_fs_devices->devices, dev_list) >> + btrfs_sysfs_remove_device(device); >> } >> >> return 0; >> @@ -1271,44 +1274,81 @@ static struct kobj_type devid_ktype = { >> .release = btrfs_release_devid_kobj, >> }; >> >> +static int btrfs_sysfs_add_device(struct btrfs_device *device) >> +{ >> + int ret; >> + struct kobject *devices_kobj; >> + struct kobject *devinfo_kobj; >> + >> + /* >> + * make sure we use the fs_info::fs_devices to fetch the kobjects >> + * even for the seed fs_devices >> + */ >> + devices_kobj = device->fs_devices->fs_info->fs_devices->devices_kobj; >> + devinfo_kobj = device->fs_devices->fs_info->fs_devices->devinfo_kobj; >> + ASSERT(devices_kobj); >> + ASSERT(devinfo_kobj); >> + >> + if (device->bdev) { >> + struct hd_struct *disk; >> + struct kobject *disk_kobj; >> + >> + disk = device->bdev->bd_part; >> + disk_kobj = &part_to_dev(disk)->kobj; >> + >> + ret = sysfs_create_link(devices_kobj, disk_kobj, >> + disk_kobj->name); >> + if (ret) { >> + btrfs_warn(device->fs_info, >> + "sysfs create device link failed %d devid %llu", >> + ret, device->devid); >> + return ret; >> + } >> + } >> + >> + init_completion(&device->kobj_unregister); >> + ret = kobject_init_and_add(&device->devid_kobj, &devid_ktype, >> + devinfo_kobj, "%llu", device->devid); >> + if (ret) { >> + kobject_put(&device->devid_kobj); >> + btrfs_warn(device->fs_info, >> + "sysfs devinfo init failed %d devid %llu", >> + ret, device->devid); >> + } >> + >> + return ret; >> +} >> + >> int btrfs_sysfs_add_devices_dir(struct btrfs_fs_devices *fs_devices, >> - struct btrfs_device *one_device) >> + struct btrfs_device *device) >> { >> - int error = 0; >> - struct btrfs_device *dev; >> + int ret = 0; >> unsigned int nofs_flag; >> + struct btrfs_fs_devices *seed_fs_devices; >> >> nofs_flag = memalloc_nofs_save(); >> - list_for_each_entry(dev, &fs_devices->devices, dev_list) { >> >> - if (one_device && one_device != dev) >> - continue; >> + if (device) >> + return btrfs_sysfs_add_device(device); >> >> - if (dev->bdev) { >> - struct hd_struct *disk; >> - struct kobject *disk_kobj; >> - >> - disk = dev->bdev->bd_part; >> - disk_kobj = &part_to_dev(disk)->kobj; >> - >> - error = sysfs_create_link(fs_devices->devices_kobj, >> - disk_kobj, disk_kobj->name); >> - if (error) >> - break; >> - } >> + list_for_each_entry(device, &fs_devices->devices, dev_list) { >> + ret = btrfs_sysfs_add_device(device); >> + if (ret) >> + goto out; >> + } >> >> - init_completion(&dev->kobj_unregister); >> - error = kobject_init_and_add(&dev->devid_kobj, &devid_ktype, >> - fs_devices->devinfo_kobj, "%llu", >> - dev->devid); >> - if (error) { >> - kobject_put(&dev->devid_kobj); >> - break; >> + list_for_each_entry(seed_fs_devices, &fs_devices->seed_list, seed_list) { >> + list_for_each_entry(device, &seed_fs_devices->devices, dev_list) { >> + ret = btrfs_sysfs_add_device(device); >> + if (ret) >> + goto out; >> } >> } >> + >> +out: >> memalloc_nofs_restore(nofs_flag); >> >> - return error; >> + return ret; >> } >> >> void btrfs_kobject_uevent(struct block_device *bdev, enum kobject_action action) >>