Re: [PATCH] btrfs: ioctl BTRFS_IOC_FS_INFO and BTRFS_IOC_DEV_INFO miss-matched with slots

[Shilong Wang <wangshilong1991@gmail.com>]

2014-05-16 23:13 GMT+08:00 Anand Jain <Anand.Jain@oracle.com>:
>
>
> On 16/05/14 22:40, Shilong Wang wrote:
>>
>> 2014-05-16 22:06 GMT+08:00 Anand Jain <anand.jain@oracle.com>:
>>>
>>> BTRFS_IOC_FS_INFO return num_devices which does not include seed disks,
>>> BTRFS_IOC_DEV_INFO fetches seed disk when probed. So in this case hits
>>> the btrfs-progs bug:
>>>              get_fs_info()
>>>              ::
>>>                      BUG_ON(ndevs >= fi_args->num_devices);
>>> which is very easy to hit by using btrfs filesystem show.
>>>
>>> This patch will make BTRFS_IOC_DEV_INFO ioctl to provide disks only
>>> of the FSID being probed (seed disks are under different FSID).
>>>
>>> which means when seed is still not deleted from the sprout the btrfs
>>> filesystem show command will show disks them under their
>>> respective FSIDs
>>
>>
>> Just a quick comment:
>>
>> Newly created filesystem is based on existed seeding filesystem.
>> Though they have different fsid, newly created filesystem devices
>> should include seed devices, from seed device filesytem, they can not
>> see newly created filesystem devices! No?
>>
>> Will the follow patch change the above behavior?
>
>
>  Yes, as the dev info list does not contain the seed disk
>  so is the btrfs fi show output. Do you think its better
>  to show seed and sprout "disks together" ? other way is
>  indicate the seed fsid against the added disk until
>  seed is deleted.

IMO, i think dev info list should contain seed disks, since new filesystem
can access their data.

Maybe a better way 'file show' will tell users which devices are seed devices..

>
> Thanks. Anand
>
>
>> Thanks,
>> Wang
>>>
>>>
>>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>>> ---
>>>   fs/btrfs/ioctl.c |    3 ++-
>>>   1 files changed, 2 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
>>> index ff27c08..902d279 100644
>>> --- a/fs/btrfs/ioctl.c
>>> +++ b/fs/btrfs/ioctl.c
>>> @@ -2584,7 +2584,8 @@ static long btrfs_ioctl_dev_info(struct btrfs_root
>>> *root, void __user *arg)
>>>                  s_uuid = di_args->uuid;
>>>
>>>          mutex_lock(&fs_devices->device_list_mutex);
>>> -       dev = btrfs_find_device(root->fs_info, di_args->devid, s_uuid,
>>> NULL);
>>> +       dev = btrfs_find_device(root->fs_info, di_args->devid, s_uuid,
>>> +                               fs_devices->fsid);
>>>
>>>          if (!dev) {
>>>                  ret = -ENODEV;
>>> --
>>> 1.7.1
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>