[PATCH] btrfs-progs: btrfstune: Register new UUIDs after uuid change

[PATCH] btrfs-progs: btrfstune: Register new UUIDs after uuid change

[Qu Wenruo]

For multi-device btrfs, after UUID change we should info kernel, or new
fs can't be mounted due to false alert on missing devices.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 btrfstune.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/btrfstune.c b/btrfstune.c
index 15dde90..23d06ce 100644
--- a/btrfstune.c
+++ b/btrfstune.c
@@ -369,6 +369,15 @@ static int change_uuid(struct btrfs_fs_info *fs_info, const char *new_fsid_str)
 	fs_info->new_fsid = NULL;
 	fs_info->new_chunk_tree_uuid = NULL;
 	printf("Fsid change finished\n");
+
+	/*
+	 * Register new devices, or multi-volume btrfs can't be mounted until
+	 * device scan happens.
+	 * Ignore any error, as such register is optional.
+	 */
+	printf("Register new UUIDs(error can be ignored)\n");
+	btrfs_register_all_devices();
+
 out:
 	return ret;
 }
-- 
2.10.0

Re: [PATCH] btrfs-progs: btrfstune: Register new UUIDs after uuid change

[Anand Jain]

On 10/10/16 17:21, Qu Wenruo wrote:
> For multi-device btrfs, after UUID change we should info kernel, or new
> fs can't be mounted due to false alert on missing devices.
>
> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> ---
>  btrfstune.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/btrfstune.c b/btrfstune.c
> index 15dde90..23d06ce 100644
> --- a/btrfstune.c
> +++ b/btrfstune.c
> @@ -369,6 +369,15 @@ static int change_uuid(struct btrfs_fs_info *fs_info, const char *new_fsid_str)
>  	fs_info->new_fsid = NULL;
>  	fs_info->new_chunk_tree_uuid = NULL;
>  	printf("Fsid change finished\n");
> +
> +	/*
> +	 * Register new devices, or multi-volume btrfs can't be mounted until
> +	 * device scan happens.
> +	 * Ignore any error, as such register is optional.
> +	 */
> +	printf("Register new UUIDs(error can be ignored)\n");

  Whats the error in particular in this context. ?

> +	btrfs_register_all_devices();

  That means after a reboot -> change uuid it will register the devices 
though the devices weren't registered to the kernel before.

  Its fair enough just remind user to run dev scan so that kernel can 
see them.

Thanks, Anand


> +
>  out:
>  	return ret;
>  }
>

Re: [PATCH] btrfs-progs: btrfstune: Register new UUIDs after uuid change

[David Sterba]

On Mon, Oct 10, 2016 at 06:54:08PM +0800, Anand Jain wrote:
> 
> 
> On 10/10/16 17:21, Qu Wenruo wrote:
> > For multi-device btrfs, after UUID change we should info kernel, or new
> > fs can't be mounted due to false alert on missing devices.
> >
> > Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> > ---
> >  btrfstune.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> >
> > diff --git a/btrfstune.c b/btrfstune.c
> > index 15dde90..23d06ce 100644
> > --- a/btrfstune.c
> > +++ b/btrfstune.c
> > @@ -369,6 +369,15 @@ static int change_uuid(struct btrfs_fs_info *fs_info, const char *new_fsid_str)
> >  	fs_info->new_fsid = NULL;
> >  	fs_info->new_chunk_tree_uuid = NULL;
> >  	printf("Fsid change finished\n");
> > +
> > +	/*
> > +	 * Register new devices, or multi-volume btrfs can't be mounted until
> > +	 * device scan happens.
> > +	 * Ignore any error, as such register is optional.
> > +	 */
> > +	printf("Register new UUIDs(error can be ignored)\n");
> 
>   Whats the error in particular in this context. ?

If /dev/btrfs-control cannot be opened by the user, in
btrfs_register_one_device() .

> > +	btrfs_register_all_devices();
> 
>   That means after a reboot -> change uuid it will register the devices 
> though the devices weren't registered to the kernel before.
> 
>   Its fair enough just remind user to run dev scan so that kernel can 
> see them.

This is similar to mkfs that is not able to register the devices for
the same reason.

Re: [PATCH] btrfs-progs: btrfstune: Register new UUIDs after uuid change

[Anand Jain]

On 10/10/16 19:08, David Sterba wrote:
> On Mon, Oct 10, 2016 at 06:54:08PM +0800, Anand Jain wrote:
>>
>>
>> On 10/10/16 17:21, Qu Wenruo wrote:
>>> For multi-device btrfs, after UUID change we should info kernel, or new
>>> fs can't be mounted due to false alert on missing devices.
>>>
>>> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
>>> ---
>>>  btrfstune.c | 9 +++++++++
>>>  1 file changed, 9 insertions(+)
>>>
>>> diff --git a/btrfstune.c b/btrfstune.c
>>> index 15dde90..23d06ce 100644
>>> --- a/btrfstune.c
>>> +++ b/btrfstune.c
>>> @@ -369,6 +369,15 @@ static int change_uuid(struct btrfs_fs_info *fs_info, const char *new_fsid_str)
>>>  	fs_info->new_fsid = NULL;
>>>  	fs_info->new_chunk_tree_uuid = NULL;
>>>  	printf("Fsid change finished\n");
>>> +
>>> +	/*
>>> +	 * Register new devices, or multi-volume btrfs can't be mounted until
>>> +	 * device scan happens.
>>> +	 * Ignore any error, as such register is optional.
>>> +	 */
>>> +	printf("Register new UUIDs(error can be ignored)\n");
>>
>>   Whats the error in particular in this context. ?
>
> If /dev/btrfs-control cannot be opened by the user, in
> btrfs_register_one_device() .

  I was wondering if there is any error specific to change in FSID ? 
looks like there isn't.

>>> +	btrfs_register_all_devices();
>>
>>   That means after a reboot -> change uuid it will register the devices
>> though the devices weren't registered to the kernel before.
>>
>>   Its fair enough just remind user to run dev scan so that kernel can
>> see them.
>
> This is similar to mkfs that is not able to register the devices for
> the same reason.

  right. inline with mkfs.btrfs -f <old-fsid>

  makes sense.

Thanks, Anand


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