Re: [Qemu-devel] [PATCH] block/rbd: Remove unused local variable

[Christian Brunner <chb@muc.de>]

2011/5/22 Stefan Weil <weil@mail.berlios.de>:
> Am 07.05.2011 22:15, schrieb Stefan Weil:
>>
>> cppcheck report:
>> rbd.c:246: style: Variable 'snap' is assigned a value that is never used
>>
>> Remove snap and the related code.
>>
>> Cc: Christian Brunner<chb@muc.de>
>> Cc: Kevin Wolf<kwolf@redhat.com>
>> Signed-off-by: Stefan Weil<weil@mail.berlios.de>
>> ---
>>  block/rbd.c |    4 ----
>>  1 files changed, 0 insertions(+), 4 deletions(-)
>>
>> diff --git a/block/rbd.c b/block/rbd.c
>> index 249a590..5c7d44e 100644
>> --- a/block/rbd.c
>> +++ b/block/rbd.c
>> @@ -524,7 +524,6 @@ static int rbd_open(BlockDriverState *bs, const char
>> *filename, int flags)
>>      RbdHeader1 *header;
>>      char pool[RBD_MAX_SEG_NAME_SIZE];
>>      char snap_buf[RBD_MAX_SEG_NAME_SIZE];
>> -    char *snap = NULL;
>>      char *hbuf = NULL;
>>      int r;
>>
>> @@ -533,9 +532,6 @@ static int rbd_open(BlockDriverState *bs, const char
>> *filename, int flags)
>>                        s->name, sizeof(s->name))<  0) {
>>          return -EINVAL;
>>      }
>> -    if (snap_buf[0] != '\0') {
>> -        snap = snap_buf;
>> -    }
>>
>>      if ((r = rados_initialize(0, NULL))<  0) {
>>          error_report("error initializing");
>>
>
> What about this patch? Can it be applied to the block branch?
>
> Regards,
> Stefan W.

No objections on my side. You can add:

Reviewed-by: Christian Brunner <chb@muc.de>

The questions is how we continue with the rbd driver. Recent ceph
versions had some changes in librados that are incompatible with the
current driver. We have to options now:

1. Change the function calls for new librados versions (I could
provide a patch for this).
2. Use librbd (see Josh's patches).

Using librbd simplifies the qemu driver a lot and gives us consistency
with the kernel driver. - I would prefer this. (Please note that there
is a race condition in the current librbd versions, that crashes qemu
under high i/o load, but I'm fairly confident, that Josh will have
sorted this out by the time 0.15 is released).

Regards,
Christian