Re: [PATCH RFC] btrfs: Add ctime/mtime update for btrfs device add/remove.

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

-------- Original Message --------
Subject: Re: [PATCH RFC] btrfs: Add ctime/mtime update for btrfs device 
add/remove.
From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Date: 2014年05月29日 20:43
> On Wed, Apr 16, 2014 at 05:02:32PM +0800, Qu Wenruo wrote:
>> @@ -1704,10 +1720,14 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
>>   
>>   	ret = 0;
>>   
>> -	/* Notify udev that device has changed */
>> -	if (bdev)
>> +	if (bdev) {
>> +		/* Notify udev that device has changed */
>>   		btrfs_kobject_uevent(bdev, KOBJ_CHANGE);
>>   
>> +		/* Update ctime/mtime for device path for libblkid */
>> +		update_dev_time(device_path);
> The change on the device comes after the uevent notification, is it
> possible that the event is delivered and processed before the device
> times are updated? I would say so.
Yes, udev event is delivered before device times updated, but now 
btrfs-progs still use libblkid to do device scan things
as default, so I didn't catch the point.

Would you please tell me what the problem is?

Thanks,
Qu
>
>> +	}
>> +
>>   error_brelse:
>>   	brelse(bh);
>>   	if (bdev)