From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:43081 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756625Ab2LGRHX (ORCPT ); Fri, 7 Dec 2012 12:07:23 -0500 Message-ID: <50C2238F.7000004@oracle.com> Date: Sat, 08 Dec 2012 01:12:47 +0800 From: Anand Jain MIME-Version: 1.0 To: Lukas Czerner CC: linux-btrfs@vger.kernel.org Subject: Re: [PATCH] btrfs: Notify udev when removing device References: <1354821948-18855-1-git-send-email-lczerner@redhat.com> In-Reply-To: <1354821948-18855-1-git-send-email-lczerner@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: It works. Nice fix. Thanks Anand On 12/07/2012 03:25 AM, Lukas Czerner wrote: > Currently udev does not know about the device being removed from the > file system. This may result in the situation where we're unable to > mount the file system by UUID or by LABEL because the by-uuid and > by-label links may still point to the device which is no longer part of > the btrfs file system and hence does not have any btrfs super block. > > It can be easily reproduced by the following: > > mkfs.btrfs -L bugfs /dev/loop[0-6] > mount /dev/loop0 /mnt/test > btrfs device delete /dev/loop0 /mnt/test > umount /mnt/test > > mount LABEL=bugfs /mnt/test <---- this fails > > then see: > > ls -l /dev/disk/by-label/bugfs > > which will still point to the /dev/loop0 > > We did not noticed this before because libblkid would send the udev > event for us when it notice that the link does not fit the reality, > however it does not do that anymore and completely relies on udev > information. > > Fix this by sending the KOBJ_CHANGE event to the bdev kobject after > successful device removal. > > Note that this does not affect device addition, because we will open the > device prior the addition from userspace and udev will notice that and > reread the device afterwards. > > Signed-off-by: Lukas Czerner > --- > fs/btrfs/volumes.c | 16 ++++++++++++++++ > 1 files changed, 16 insertions(+), 0 deletions(-) > > diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c > index 0f5ebb7..95c6f7d 100644 > --- a/fs/btrfs/volumes.c > +++ b/fs/btrfs/volumes.c > @@ -71,6 +71,19 @@ static void free_fs_devices(struct btrfs_fs_devices *fs_devices) > kfree(fs_devices); > } > > +static void btrfs_kobject_uevent(struct block_device *bdev, > + enum kobject_action action) > +{ > + int ret; > + > + ret = kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, action); > + if (ret) > + pr_warn("Sending event '%d' to kobject: '%s' (%p): failed\n", > + action, > + kobject_name(&disk_to_dev(bdev->bd_disk)->kobj), > + &disk_to_dev(bdev->bd_disk)->kobj); > +} > + > void btrfs_cleanup_fs_uuids(void) > { > struct btrfs_fs_devices *fs_devices; > @@ -1493,6 +1506,9 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path) > > ret = 0; > > + /* Notify udev that device has changed */ > + btrfs_kobject_uevent(bdev, KOBJ_CHANGE); > + > error_brelse: > brelse(bh); > error_close: >