On 24.04.20 11:53, Max Reitz wrote:
> On 24.04.20 00:17, Eric Blake wrote:
>> There are several callers that need to create a new block backend from
>> an existing BDS; make the task slightly easier with a common helper
>> routine.
>>
>> Suggested-by: Max Reitz <mreitz@redhat.com>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>> ---
>>  include/sysemu/block-backend.h |  2 ++
>>  block/block-backend.c          | 23 +++++++++++++++++++++++
>>  block/crypto.c                 |  8 +++-----
>>  block/parallels.c              |  7 +++----
>>  block/qcow.c                   |  7 +++----
>>  block/qcow2.c                  | 15 ++++++---------
>>  block/qed.c                    |  7 +++----
>>  block/sheepdog.c               |  9 ++++-----
>>  block/vdi.c                    |  7 +++----
>>  block/vhdx.c                   |  7 +++----
>>  block/vmdk.c                   |  9 ++++-----
>>  block/vpc.c                    |  7 +++----
>>  blockdev.c                     |  8 +++-----
>>  blockjob.c                     |  7 ++-----
>>  14 files changed, 65 insertions(+), 58 deletions(-)
> 
> Reviewed-by: Max Reitz <mreitz@redhat.com>

(With the Patchew warning fixed, of course (i.e., we should set ret to
-EPERM or something in qcow.c))

>> diff --git a/blockdev.c b/blockdev.c
>> index 5faddaa7052f..f43426ed5fbc 100644
>> --- a/blockdev.c
>> +++ b/blockdev.c
> 
> [...]
> 
>> @@ -2734,14 +2733,13 @@ void qmp_block_resize(bool has_device, const char *device,
>>          goto out;
>>      }
>>
>> -    blk = blk_new(bdrv_get_aio_context(bs), BLK_PERM_RESIZE, BLK_PERM_ALL);
>> -    ret = blk_insert_bs(blk, bs, errp);
>> -    if (ret < 0) {
>> +    blk = blk_new_with_bs(bs, BLK_PERM_RESIZE, BLK_PERM_ALL, errp);
>> +    if (!blk) {
>>          goto out;
>>      }
>>
>>      bdrv_drained_begin(bs);
>> -    ret = blk_truncate(blk, size, false, PREALLOC_MODE_OFF, errp);
>> +    blk_truncate(blk, size, false, PREALLOC_MODE_OFF, errp);
> 
> This is also addressed by
> https://lists.nongnu.org/archive/html/qemu-devel/2020-04/msg03656.html,
> but it does make sense to fix it here, too.  Well, whichever lands first
> lands first, I suppose (so @ret can be dropped).

I intended to affix the “(so @ret can be dropped)” to the first
sentence, not the second one...

Max