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Sat, 29 Aug 2020 11:44:42 +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 07TBePZj038245; Sat, 29 Aug 2020 11:44:42 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by aserp3020.oracle.com with ESMTP id 337eu0v56x-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Sat, 29 Aug 2020 11:44:41 +0000 Received: from abhmp0007.oracle.com (abhmp0007.oracle.com [141.146.116.13]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 07TBie6p022643; Sat, 29 Aug 2020 11:44:40 GMT Received: from [192.168.1.102] (/39.109.231.106) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Sat, 29 Aug 2020 04:44:40 -0700 Subject: Re: [PATCH 1/2] btrfs: initialize sysfs devid and device link for seed device From: Anand Jain To: linux-btrfs@vger.kernel.org Cc: josef@toxicpanda.com References: <2c7ca821f53d71d6c1a4e1f1c969c1d8e686021a.1598012410.git.anand.jain@oracle.com> Message-ID: Date: Sat, 29 Aug 2020 19:44:37 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.1.1 MIME-Version: 1.0 In-Reply-To: <2c7ca821f53d71d6c1a4e1f1c969c1d8e686021a.1598012410.git.anand.jain@oracle.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9727 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 bulkscore=0 mlxscore=0 spamscore=0 phishscore=0 mlxlogscore=999 adultscore=0 suspectscore=1 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008290093 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9727 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 clxscore=1015 mlxscore=0 malwarescore=0 lowpriorityscore=0 adultscore=0 impostorscore=0 priorityscore=1501 phishscore=0 suspectscore=1 spamscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2008290093 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 21/8/20 9:15 pm, 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 > --- > fs/btrfs/sysfs.c | 30 ++++++++++++++++++++---------- > 1 file changed, 20 insertions(+), 10 deletions(-) > > diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c > index 88fd4ce937b8..85403fc3d5c7 100644 > --- a/fs/btrfs/sysfs.c > +++ b/fs/btrfs/sysfs.c > @@ -1154,20 +1154,20 @@ int btrfs_sysfs_add_space_info_type(struct btrfs_fs_info *fs_info, > /* 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) > + struct btrfs_device *one_device) > { > struct hd_struct *disk; > struct kobject *disk_kobj; > + struct kobject *devices_kobj = fs_devices->devices_kobj; > > - if (!fs_devices->devices_kobj) > + if (!devices_kobj) > return -EINVAL; > > 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); > + sysfs_remove_link(devices_kobj, disk_kobj->name); > } > > kobject_del(&one_device->devid_kobj); > @@ -1178,19 +1178,23 @@ int btrfs_sysfs_remove_devices_dir(struct btrfs_fs_devices *fs_devices, > return 0; > } > > +again: > 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); > + sysfs_remove_link(devices_kobj, disk_kobj->name); > } > kobject_del(&one_device->devid_kobj); > kobject_put(&one_device->devid_kobj); > > wait_for_completion(&one_device->kobj_unregister); > } > + while (fs_devices->seed) { > + fs_devices = fs_devices->seed; > + goto again; > + } > > return 0; > } > @@ -1279,8 +1283,11 @@ int btrfs_sysfs_add_devices_dir(struct btrfs_fs_devices *fs_devices, > int error = 0; > struct btrfs_device *dev; > unsigned int nofs_flag; > + struct kobject *devices_kobj = fs_devices->devices_kobj; > + struct kobject *devinfo_kobj = fs_devices->devinfo_kobj; > > nofs_flag = memalloc_nofs_save(); > +again: > list_for_each_entry(dev, &fs_devices->devices, dev_list) { > > if (one_device && one_device != dev) > @@ -1293,21 +1300,24 @@ int btrfs_sysfs_add_devices_dir(struct btrfs_fs_devices *fs_devices, > 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); > + error = sysfs_create_link(devices_kobj, disk_kobj, > + disk_kobj->name); > if (error) > break; > } > > init_completion(&dev->kobj_unregister); > error = kobject_init_and_add(&dev->devid_kobj, &devid_ktype, > - fs_devices->devinfo_kobj, "%llu", > - dev->devid); > + devinfo_kobj, "%llu", dev->devid); > if (error) { > kobject_put(&dev->devid_kobj); > break; > } > } > + while(fs_devices->seed) { > + fs_devices = fs_devices->seed; > + goto again; > + } > memalloc_nofs_restore(nofs_flag); > > return error; > Ping? Thanks, Anand