diff mbox

[v5,1/4] Add new block driver interface to add/delete a BDS's child

Message ID 1442907862-21376-2-git-send-email-wency@cn.fujitsu.com
State New
Headers show

Commit Message

Wen Congyang Sept. 22, 2015, 7:44 a.m. UTC 
In some cases, we want to take a quorum child offline, and take
another child online.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
 block.c                   | 50 +++++++++++++++++++++++++++++++++++++++++++++++
 include/block/block.h     |  5 +++++
 include/block/block_int.h |  5 +++++
 3 files changed, 60 insertions(+)

Comments

Alberto Garcia Oct. 7, 2015, 1:35 p.m. UTC | #1 
On Tue 22 Sep 2015 09:44:19 AM CEST, Wen Congyang <wency@cn.fujitsu.com> wrote:
> In some cases, we want to take a quorum child offline, and take
> another child online.
>
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>

> +void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
> +                    Error **errp)
> +{
> +
> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
> +        error_setg(errp, "The BDS %s doesn't support adding a child",
> +                   bdrv_get_device_or_node_name(parent_bs));
> +        return;
> +    }
> +
> +    if (!QLIST_EMPTY(&child_bs->parents)) {
> +        error_setg(errp, "The BDS %s already has parent",
> +                   child_bs->node_name);

I think there's one 'a' missing:

  "The BDS %s already has a parent".

I also don't think we should use "BDS" in error messages, that's an
acronym for the name of a C data type, not something that the user is
supposed to know about.

I suggest using 'Node' instead.

Otherwise the patch looks good to me, thanks!

Berto
Max Reitz Oct. 7, 2015, 6:33 p.m. UTC | #2 
On 22.09.2015 09:44, Wen Congyang wrote:
> In some cases, we want to take a quorum child offline, and take
> another child online.
> 
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> ---
>  block.c                   | 50 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/block/block.h     |  5 +++++
>  include/block/block_int.h |  5 +++++
>  3 files changed, 60 insertions(+)
> 
> diff --git a/block.c b/block.c
> index e815d73..1b25e43 100644
> --- a/block.c
> +++ b/block.c
> @@ -4265,3 +4265,53 @@ BlockAcctStats *bdrv_get_stats(BlockDriverState *bs)
>  {
>      return &bs->stats;
>  }
> +
> +/*
> + * Hot add/remove a BDS's child. So the user can take a child offline when
> + * it is broken and take a new child online
> + */
> +void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
> +                    Error **errp)
> +{
> +
> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
> +        error_setg(errp, "The BDS %s doesn't support adding a child",
> +                   bdrv_get_device_or_node_name(parent_bs));
> +        return;
> +    }
> +
> +    if (!QLIST_EMPTY(&child_bs->parents)) {
> +        error_setg(errp, "The BDS %s already has parent",
> +                   child_bs->node_name);
> +        return;
> +    }
> +
> +    parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
> +}
> +
> +void bdrv_del_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
> +                    Error **errp)
> +{
> +    BdrvChild *child;
> +
> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
> +        error_setg(errp, "The BDS %s doesn't support removing a child",
> +                   bdrv_get_device_or_node_name(parent_bs));
> +        return;
> +    }
> +
> +    QLIST_FOREACH(child, &parent_bs->children, next) {
> +        if (child->bs == child_bs) {
> +            break;
> +        }
> +    }
> +
> +    if (!child) {
> +        error_setg(errp, "BDS %s is not a child of %s",
> +                   bdrv_get_device_or_node_name(child_bs),
> +                   bdrv_get_device_or_node_name(parent_bs));
> +        return;
> +    }
> +
> +    parent_bs->drv->bdrv_del_child(parent_bs, child_bs, errp);

How about we make this (BlockDriver.bdrv_del_child()) take a BdrvChild
instead of a BDS? We could even make bdrv_del_child() as a whole take a
BdrvChild parameter, but I don't suppose that would help much.

Max

> +}
> diff --git a/include/block/block.h b/include/block/block.h
> index ef67353..665c56f 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -616,4 +616,9 @@ void bdrv_flush_io_queue(BlockDriverState *bs);
>  
>  BlockAcctStats *bdrv_get_stats(BlockDriverState *bs);
>  
> +void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
> +                    Error **errp);
> +void bdrv_del_child(BlockDriverState *parent, BlockDriverState *child,
> +                    Error **errp);
> +
>  #endif
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 2f2c47b..64cbc55 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -288,6 +288,11 @@ struct BlockDriver {
>       */
>      int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
>  
> +    void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child,
> +                           Error **errp);
> +    void (*bdrv_del_child)(BlockDriverState *parent, BlockDriverState *child,
> +                           Error **errp);
> +
>      QLIST_ENTRY(BlockDriver) list;
>  };
>  
>
Dr. David Alan Gilbert Oct. 7, 2015, 7 p.m. UTC | #3 
* Wen Congyang (wency@cn.fujitsu.com) wrote:
> In some cases, we want to take a quorum child offline, and take
> another child online.

Hi,
  Have you checked the output of 'info block' after adding/deleting a child?
I'm using one of your older worlds (from a few months ago) and I found I had
to add a 

    bdrv_refresh_filename(bs);

to get the output of 'info block' to show the new child.
I don't see it in this version.

Dave


> 
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> ---
>  block.c                   | 50 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/block/block.h     |  5 +++++
>  include/block/block_int.h |  5 +++++
>  3 files changed, 60 insertions(+)
> 
> diff --git a/block.c b/block.c
> index e815d73..1b25e43 100644
> --- a/block.c
> +++ b/block.c
> @@ -4265,3 +4265,53 @@ BlockAcctStats *bdrv_get_stats(BlockDriverState *bs)
>  {
>      return &bs->stats;
>  }
> +
> +/*
> + * Hot add/remove a BDS's child. So the user can take a child offline when
> + * it is broken and take a new child online
> + */
> +void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
> +                    Error **errp)
> +{
> +
> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
> +        error_setg(errp, "The BDS %s doesn't support adding a child",
> +                   bdrv_get_device_or_node_name(parent_bs));
> +        return;
> +    }
> +
> +    if (!QLIST_EMPTY(&child_bs->parents)) {
> +        error_setg(errp, "The BDS %s already has parent",
> +                   child_bs->node_name);
> +        return;
> +    }
> +
> +    parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
> +}
> +
> +void bdrv_del_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
> +                    Error **errp)
> +{
> +    BdrvChild *child;
> +
> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
> +        error_setg(errp, "The BDS %s doesn't support removing a child",
> +                   bdrv_get_device_or_node_name(parent_bs));
> +        return;
> +    }
> +
> +    QLIST_FOREACH(child, &parent_bs->children, next) {
> +        if (child->bs == child_bs) {
> +            break;
> +        }
> +    }
> +
> +    if (!child) {
> +        error_setg(errp, "BDS %s is not a child of %s",
> +                   bdrv_get_device_or_node_name(child_bs),
> +                   bdrv_get_device_or_node_name(parent_bs));
> +        return;
> +    }
> +
> +    parent_bs->drv->bdrv_del_child(parent_bs, child_bs, errp);
> +}
> diff --git a/include/block/block.h b/include/block/block.h
> index ef67353..665c56f 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -616,4 +616,9 @@ void bdrv_flush_io_queue(BlockDriverState *bs);
>  
>  BlockAcctStats *bdrv_get_stats(BlockDriverState *bs);
>  
> +void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
> +                    Error **errp);
> +void bdrv_del_child(BlockDriverState *parent, BlockDriverState *child,
> +                    Error **errp);
> +
>  #endif
> diff --git a/include/block/block_int.h b/include/block/block_int.h
> index 2f2c47b..64cbc55 100644
> --- a/include/block/block_int.h
> +++ b/include/block/block_int.h
> @@ -288,6 +288,11 @@ struct BlockDriver {
>       */
>      int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
>  
> +    void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child,
> +                           Error **errp);
> +    void (*bdrv_del_child)(BlockDriverState *parent, BlockDriverState *child,
> +                           Error **errp);
> +
>      QLIST_ENTRY(BlockDriver) list;
>  };
>  
> -- 
> 2.4.3
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
Wen Congyang Oct. 8, 2015, 2:03 a.m. UTC | #4 
On 10/08/2015 03:00 AM, Dr. David Alan Gilbert wrote:
> * Wen Congyang (wency@cn.fujitsu.com) wrote:
>> In some cases, we want to take a quorum child offline, and take
>> another child online.
> 
> Hi,
>   Have you checked the output of 'info block' after adding/deleting a child?
> I'm using one of your older worlds (from a few months ago) and I found I had
> to add a 
> 
>     bdrv_refresh_filename(bs);
> 
> to get the output of 'info block' to show the new child.
> I don't see it in this version.

Max sent a patch series to drop BDS.filename, so I don't call bdrv_refresh_filename()
here. If the BDS is not the top BDS, 'info block' still shows the wrong child.

Thanks
Wen Congyang

> 
> Dave
> 
> 
>>
>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
>> Reviewed-by: Eric Blake <eblake@redhat.com>
>> ---
>>  block.c                   | 50 +++++++++++++++++++++++++++++++++++++++++++++++
>>  include/block/block.h     |  5 +++++
>>  include/block/block_int.h |  5 +++++
>>  3 files changed, 60 insertions(+)
>>
>> diff --git a/block.c b/block.c
>> index e815d73..1b25e43 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -4265,3 +4265,53 @@ BlockAcctStats *bdrv_get_stats(BlockDriverState *bs)
>>  {
>>      return &bs->stats;
>>  }
>> +
>> +/*
>> + * Hot add/remove a BDS's child. So the user can take a child offline when
>> + * it is broken and take a new child online
>> + */
>> +void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
>> +                    Error **errp)
>> +{
>> +
>> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
>> +        error_setg(errp, "The BDS %s doesn't support adding a child",
>> +                   bdrv_get_device_or_node_name(parent_bs));
>> +        return;
>> +    }
>> +
>> +    if (!QLIST_EMPTY(&child_bs->parents)) {
>> +        error_setg(errp, "The BDS %s already has parent",
>> +                   child_bs->node_name);
>> +        return;
>> +    }
>> +
>> +    parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
>> +}
>> +
>> +void bdrv_del_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
>> +                    Error **errp)
>> +{
>> +    BdrvChild *child;
>> +
>> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
>> +        error_setg(errp, "The BDS %s doesn't support removing a child",
>> +                   bdrv_get_device_or_node_name(parent_bs));
>> +        return;
>> +    }
>> +
>> +    QLIST_FOREACH(child, &parent_bs->children, next) {
>> +        if (child->bs == child_bs) {
>> +            break;
>> +        }
>> +    }
>> +
>> +    if (!child) {
>> +        error_setg(errp, "BDS %s is not a child of %s",
>> +                   bdrv_get_device_or_node_name(child_bs),
>> +                   bdrv_get_device_or_node_name(parent_bs));
>> +        return;
>> +    }
>> +
>> +    parent_bs->drv->bdrv_del_child(parent_bs, child_bs, errp);
>> +}
>> diff --git a/include/block/block.h b/include/block/block.h
>> index ef67353..665c56f 100644
>> --- a/include/block/block.h
>> +++ b/include/block/block.h
>> @@ -616,4 +616,9 @@ void bdrv_flush_io_queue(BlockDriverState *bs);
>>  
>>  BlockAcctStats *bdrv_get_stats(BlockDriverState *bs);
>>  
>> +void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
>> +                    Error **errp);
>> +void bdrv_del_child(BlockDriverState *parent, BlockDriverState *child,
>> +                    Error **errp);
>> +
>>  #endif
>> diff --git a/include/block/block_int.h b/include/block/block_int.h
>> index 2f2c47b..64cbc55 100644
>> --- a/include/block/block_int.h
>> +++ b/include/block/block_int.h
>> @@ -288,6 +288,11 @@ struct BlockDriver {
>>       */
>>      int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
>>  
>> +    void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child,
>> +                           Error **errp);
>> +    void (*bdrv_del_child)(BlockDriverState *parent, BlockDriverState *child,
>> +                           Error **errp);
>> +
>>      QLIST_ENTRY(BlockDriver) list;
>>  };
>>  
>> -- 
>> 2.4.3
>>
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> .
>
Wen Congyang Oct. 8, 2015, 2:05 a.m. UTC | #5 
On 10/07/2015 09:35 PM, Alberto Garcia wrote:
> On Tue 22 Sep 2015 09:44:19 AM CEST, Wen Congyang <wency@cn.fujitsu.com> wrote:
>> In some cases, we want to take a quorum child offline, and take
>> another child online.
>>
>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
>> Reviewed-by: Eric Blake <eblake@redhat.com>
> 
>> +void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
>> +                    Error **errp)
>> +{
>> +
>> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
>> +        error_setg(errp, "The BDS %s doesn't support adding a child",
>> +                   bdrv_get_device_or_node_name(parent_bs));
>> +        return;
>> +    }
>> +
>> +    if (!QLIST_EMPTY(&child_bs->parents)) {
>> +        error_setg(errp, "The BDS %s already has parent",
>> +                   child_bs->node_name);
> 
> I think there's one 'a' missing:
> 
>   "The BDS %s already has a parent".
> 
> I also don't think we should use "BDS" in error messages, that's an
> acronym for the name of a C data type, not something that the user is
> supposed to know about.
> 
> I suggest using 'Node' instead.
> 
> Otherwise the patch looks good to me, thanks!

OK, I will fix it in the next version

Thanks
Wen Congyang

> 
> Berto
> .
>
Wen Congyang Oct. 8, 2015, 2:06 a.m. UTC | #6 
On 10/08/2015 02:33 AM, Max Reitz wrote:
> On 22.09.2015 09:44, Wen Congyang wrote:
>> In some cases, we want to take a quorum child offline, and take
>> another child online.
>>
>> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
>> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
>> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
>> Reviewed-by: Eric Blake <eblake@redhat.com>
>> ---
>>  block.c                   | 50 +++++++++++++++++++++++++++++++++++++++++++++++
>>  include/block/block.h     |  5 +++++
>>  include/block/block_int.h |  5 +++++
>>  3 files changed, 60 insertions(+)
>>
>> diff --git a/block.c b/block.c
>> index e815d73..1b25e43 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -4265,3 +4265,53 @@ BlockAcctStats *bdrv_get_stats(BlockDriverState *bs)
>>  {
>>      return &bs->stats;
>>  }
>> +
>> +/*
>> + * Hot add/remove a BDS's child. So the user can take a child offline when
>> + * it is broken and take a new child online
>> + */
>> +void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
>> +                    Error **errp)
>> +{
>> +
>> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
>> +        error_setg(errp, "The BDS %s doesn't support adding a child",
>> +                   bdrv_get_device_or_node_name(parent_bs));
>> +        return;
>> +    }
>> +
>> +    if (!QLIST_EMPTY(&child_bs->parents)) {
>> +        error_setg(errp, "The BDS %s already has parent",
>> +                   child_bs->node_name);
>> +        return;
>> +    }
>> +
>> +    parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
>> +}
>> +
>> +void bdrv_del_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
>> +                    Error **errp)
>> +{
>> +    BdrvChild *child;
>> +
>> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
>> +        error_setg(errp, "The BDS %s doesn't support removing a child",
>> +                   bdrv_get_device_or_node_name(parent_bs));
>> +        return;
>> +    }
>> +
>> +    QLIST_FOREACH(child, &parent_bs->children, next) {
>> +        if (child->bs == child_bs) {
>> +            break;
>> +        }
>> +    }
>> +
>> +    if (!child) {
>> +        error_setg(errp, "BDS %s is not a child of %s",
>> +                   bdrv_get_device_or_node_name(child_bs),
>> +                   bdrv_get_device_or_node_name(parent_bs));
>> +        return;
>> +    }
>> +
>> +    parent_bs->drv->bdrv_del_child(parent_bs, child_bs, errp);
> 
> How about we make this (BlockDriver.bdrv_del_child()) take a BdrvChild
> instead of a BDS? We could even make bdrv_del_child() as a whole take a
> BdrvChild parameter, but I don't suppose that would help much.

bdrv_add_child() takes a BDS, so I use BDS here.

Thanks
Wen Congyang

> 
> Max
> 
>> +}
>> diff --git a/include/block/block.h b/include/block/block.h
>> index ef67353..665c56f 100644
>> --- a/include/block/block.h
>> +++ b/include/block/block.h
>> @@ -616,4 +616,9 @@ void bdrv_flush_io_queue(BlockDriverState *bs);
>>  
>>  BlockAcctStats *bdrv_get_stats(BlockDriverState *bs);
>>  
>> +void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
>> +                    Error **errp);
>> +void bdrv_del_child(BlockDriverState *parent, BlockDriverState *child,
>> +                    Error **errp);
>> +
>>  #endif
>> diff --git a/include/block/block_int.h b/include/block/block_int.h
>> index 2f2c47b..64cbc55 100644
>> --- a/include/block/block_int.h
>> +++ b/include/block/block_int.h
>> @@ -288,6 +288,11 @@ struct BlockDriver {
>>       */
>>      int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
>>  
>> +    void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child,
>> +                           Error **errp);
>> +    void (*bdrv_del_child)(BlockDriverState *parent, BlockDriverState *child,
>> +                           Error **errp);
>> +
>>      QLIST_ENTRY(BlockDriver) list;
>>  };
>>  
>>
> 
>
Dr. David Alan Gilbert Oct. 8, 2015, 6:44 p.m. UTC | #7 
* Wen Congyang (wency@cn.fujitsu.com) wrote:
> On 10/08/2015 03:00 AM, Dr. David Alan Gilbert wrote:
> > * Wen Congyang (wency@cn.fujitsu.com) wrote:
> >> In some cases, we want to take a quorum child offline, and take
> >> another child online.
> > 
> > Hi,
> >   Have you checked the output of 'info block' after adding/deleting a child?
> > I'm using one of your older worlds (from a few months ago) and I found I had
> > to add a 
> > 
> >     bdrv_refresh_filename(bs);
> > 
> > to get the output of 'info block' to show the new child.
> > I don't see it in this version.
> 
> Max sent a patch series to drop BDS.filename, so I don't call bdrv_refresh_filename()
> here. If the BDS is not the top BDS, 'info block' still shows the wrong child.

Ah, so I guess you can just implement the exact_filename() function and that
will get it right?

Dave
> 
> Thanks
> Wen Congyang
> 
> > 
> > Dave
> > 
> > 
> >>
> >> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> >> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com>
> >> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> >> Reviewed-by: Eric Blake <eblake@redhat.com>
> >> ---
> >>  block.c                   | 50 +++++++++++++++++++++++++++++++++++++++++++++++
> >>  include/block/block.h     |  5 +++++
> >>  include/block/block_int.h |  5 +++++
> >>  3 files changed, 60 insertions(+)
> >>
> >> diff --git a/block.c b/block.c
> >> index e815d73..1b25e43 100644
> >> --- a/block.c
> >> +++ b/block.c
> >> @@ -4265,3 +4265,53 @@ BlockAcctStats *bdrv_get_stats(BlockDriverState *bs)
> >>  {
> >>      return &bs->stats;
> >>  }
> >> +
> >> +/*
> >> + * Hot add/remove a BDS's child. So the user can take a child offline when
> >> + * it is broken and take a new child online
> >> + */
> >> +void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
> >> +                    Error **errp)
> >> +{
> >> +
> >> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
> >> +        error_setg(errp, "The BDS %s doesn't support adding a child",
> >> +                   bdrv_get_device_or_node_name(parent_bs));
> >> +        return;
> >> +    }
> >> +
> >> +    if (!QLIST_EMPTY(&child_bs->parents)) {
> >> +        error_setg(errp, "The BDS %s already has parent",
> >> +                   child_bs->node_name);
> >> +        return;
> >> +    }
> >> +
> >> +    parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
> >> +}
> >> +
> >> +void bdrv_del_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
> >> +                    Error **errp)
> >> +{
> >> +    BdrvChild *child;
> >> +
> >> +    if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
> >> +        error_setg(errp, "The BDS %s doesn't support removing a child",
> >> +                   bdrv_get_device_or_node_name(parent_bs));
> >> +        return;
> >> +    }
> >> +
> >> +    QLIST_FOREACH(child, &parent_bs->children, next) {
> >> +        if (child->bs == child_bs) {
> >> +            break;
> >> +        }
> >> +    }
> >> +
> >> +    if (!child) {
> >> +        error_setg(errp, "BDS %s is not a child of %s",
> >> +                   bdrv_get_device_or_node_name(child_bs),
> >> +                   bdrv_get_device_or_node_name(parent_bs));
> >> +        return;
> >> +    }
> >> +
> >> +    parent_bs->drv->bdrv_del_child(parent_bs, child_bs, errp);
> >> +}
> >> diff --git a/include/block/block.h b/include/block/block.h
> >> index ef67353..665c56f 100644
> >> --- a/include/block/block.h
> >> +++ b/include/block/block.h
> >> @@ -616,4 +616,9 @@ void bdrv_flush_io_queue(BlockDriverState *bs);
> >>  
> >>  BlockAcctStats *bdrv_get_stats(BlockDriverState *bs);
> >>  
> >> +void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
> >> +                    Error **errp);
> >> +void bdrv_del_child(BlockDriverState *parent, BlockDriverState *child,
> >> +                    Error **errp);
> >> +
> >>  #endif
> >> diff --git a/include/block/block_int.h b/include/block/block_int.h
> >> index 2f2c47b..64cbc55 100644
> >> --- a/include/block/block_int.h
> >> +++ b/include/block/block_int.h
> >> @@ -288,6 +288,11 @@ struct BlockDriver {
> >>       */
> >>      int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
> >>  
> >> +    void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child,
> >> +                           Error **errp);
> >> +    void (*bdrv_del_child)(BlockDriverState *parent, BlockDriverState *child,
> >> +                           Error **errp);
> >> +
> >>      QLIST_ENTRY(BlockDriver) list;
> >>  };
> >>  
> >> -- 
> >> 2.4.3
> >>
> > --
> > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> > .
> > 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
diff mbox

Patch

diff --git a/block.c b/block.c
index e815d73..1b25e43 100644
--- a/block.c
+++ b/block.c
@@ -4265,3 +4265,53 @@  BlockAcctStats *bdrv_get_stats(BlockDriverState *bs)
 {
     return &bs->stats;
 }
+
+/*
+ * Hot add/remove a BDS's child. So the user can take a child offline when
+ * it is broken and take a new child online
+ */
+void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
+                    Error **errp)
+{
+
+    if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
+        error_setg(errp, "The BDS %s doesn't support adding a child",
+                   bdrv_get_device_or_node_name(parent_bs));
+        return;
+    }
+
+    if (!QLIST_EMPTY(&child_bs->parents)) {
+        error_setg(errp, "The BDS %s already has parent",
+                   child_bs->node_name);
+        return;
+    }
+
+    parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
+}
+
+void bdrv_del_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
+                    Error **errp)
+{
+    BdrvChild *child;
+
+    if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
+        error_setg(errp, "The BDS %s doesn't support removing a child",
+                   bdrv_get_device_or_node_name(parent_bs));
+        return;
+    }
+
+    QLIST_FOREACH(child, &parent_bs->children, next) {
+        if (child->bs == child_bs) {
+            break;
+        }
+    }
+
+    if (!child) {
+        error_setg(errp, "BDS %s is not a child of %s",
+                   bdrv_get_device_or_node_name(child_bs),
+                   bdrv_get_device_or_node_name(parent_bs));
+        return;
+    }
+
+    parent_bs->drv->bdrv_del_child(parent_bs, child_bs, errp);
+}
diff --git a/include/block/block.h b/include/block/block.h
index ef67353..665c56f 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -616,4 +616,9 @@  void bdrv_flush_io_queue(BlockDriverState *bs);
 
 BlockAcctStats *bdrv_get_stats(BlockDriverState *bs);
 
+void bdrv_add_child(BlockDriverState *parent, BlockDriverState *child,
+                    Error **errp);
+void bdrv_del_child(BlockDriverState *parent, BlockDriverState *child,
+                    Error **errp);
+
 #endif
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 2f2c47b..64cbc55 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -288,6 +288,11 @@  struct BlockDriver {
      */
     int (*bdrv_probe_geometry)(BlockDriverState *bs, HDGeometry *geo);
 
+    void (*bdrv_add_child)(BlockDriverState *parent, BlockDriverState *child,
+                           Error **errp);
+    void (*bdrv_del_child)(BlockDriverState *parent, BlockDriverState *child,
+                           Error **errp);
+
     QLIST_ENTRY(BlockDriver) list;
 };