NVME identify command data structure length

[anup shendkar]

Thanks Matthew for the explanation. I will work on the patch based on
your suggestion and send it once it is ready.

Regards,
Anup

On Tue, Aug 27, 2013 at 7:47 PM, Matthew Wilcox <willy at linux.intel.com> wrote:
> On Tue, Aug 27, 2013 at 03:50:34PM +0530, anup shendkar wrote:
>> 3. As nvme specification for IDENTIFY command says that 4096 is the
>> output buffer length, we can add following code as a potential fix.
>
> No.  The driver does not interpret the opcodes.  If you've mis-used the
> ioctl, then you get to keep both pieces.
>
> However, what we should do is check the bottom two bits of the opcode
> (ie Data Transfer in Figure 38 of NVMe 1.1).  It is clearly a broken
> command if the bottom two bits are zero and data_len is non-zero, or
> for the bottom two bits to be non-zero and data_len to be zero.
>
> Do you want to send a patch along those lines?
>
>> diff --git a/drivers/block/nvme-core.c b/drivers/block/nvme-core.c
>> index ce79a59..b1c5e72 100644
>> --- a/drivers/block/nvme-core.c
>> +++ b/drivers/block/nvme-core.c
>> @@ -1416,6 +1416,11 @@ static int nvme_user_admin_cmd(struct nvme_dev *dev,
>>         c.common.cdw10[4] = cpu_to_le32(cmd.cdw14);
>>         c.common.cdw10[5] = cpu_to_le32(cmd.cdw15);
>>
>> +       if (cmd.opcode == nvme_admin_identify) {
>> +               /* NVME Identiy command always uses 4096 data buffer */
>> +               cmd.data_len = 4096;
>> +       }
>> +
>>         length = cmd.data_len;
>>         if (cmd.data_len) {
>>                 iod = nvme_map_user_pages(dev, cmd.opcode & 1, cmd.addr,



-- 
anup shendkar