[PATCH] um: Fix WRITE_ZEROES in the UBD Driver

[Anton Ivanov]

On 16/02/2022 10:00, Frédéric Danis wrote:
> Hi,
> 
> On 26/01/2022 10:47, Anton Ivanov wrote:
>>
>>
>> On 25/01/2022 17:14, Frédéric Danis wrote:
>>> Call to fallocate with FALLOC_FL_PUNCH_HOLE on a device backed by a 
>>> sparse
>>> file can end up by missing data, zeroes data range, if the underlying 
>>> file
>>> is used with a tool like bmaptool which will referenced only used 
>>> spaces.
>>>
>>> Signed-off-by: Frédéric Danis <frederic.danis at collabora.com>
>>> ---
>>>   arch/um/drivers/ubd_kern.c  | 8 +++++++-
>>>   arch/um/include/shared/os.h | 1 +
>>>   arch/um/os-Linux/file.c     | 9 +++++++++
>>>   3 files changed, 17 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
>>> index 69d2d0049a61..b03269faef71 100644
>>> --- a/arch/um/drivers/ubd_kern.c
>>> +++ b/arch/um/drivers/ubd_kern.c
>>> @@ -1526,13 +1526,19 @@ static void do_io(struct io_thread_req *req, 
>>> struct io_desc *desc)
>>>               }
>>>               break;
>>>           case REQ_OP_DISCARD:
>>> -        case REQ_OP_WRITE_ZEROES:
>>>               n = os_falloc_punch(req->fds[bit], off, len);
>>>               if (n) {
>>>                   req->error = map_error(-n);
>>>                   return;
>>>               }
>>>               break;
>>> +        case REQ_OP_WRITE_ZEROES:
>>> +            n = os_falloc_zeroes(req->fds[bit], off, len);
>>> +            if (n) {
>>> +                req->error = map_error(-n);
>>> +                return;
>>> +            }
>>> +            break;
>>>           default:
>>>               WARN_ON_ONCE(1);
>>>               req->error = BLK_STS_NOTSUPP;
>>> diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
>>> index 00214059d9ec..fafde1d5416e 100644
>>> --- a/arch/um/include/shared/os.h
>>> +++ b/arch/um/include/shared/os.h
>>> @@ -168,6 +168,7 @@ extern unsigned os_major(unsigned long long dev);
>>>   extern unsigned os_minor(unsigned long long dev);
>>>   extern unsigned long long os_makedev(unsigned major, unsigned minor);
>>>   extern int os_falloc_punch(int fd, unsigned long long offset, int 
>>> count);
>>> +extern int os_falloc_zeroes(int fd, unsigned long long offset, int 
>>> count);
>>>   extern int os_eventfd(unsigned int initval, int flags);
>>>   extern int os_sendmsg_fds(int fd, const void *buf, unsigned int len,
>>>                 const int *fds, unsigned int fds_num);
>>> diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c
>>> index e4421dbc4c36..fc4450db59bd 100644
>>> --- a/arch/um/os-Linux/file.c
>>> +++ b/arch/um/os-Linux/file.c
>>> @@ -625,6 +625,15 @@ int os_falloc_punch(int fd, unsigned long long 
>>> offset, int len)
>>>       return n;
>>>   }
>>>   +int os_falloc_zeroes(int fd, unsigned long long offset, int len)
>>> +{
>>> +    int n = fallocate(fd, FALLOC_FL_ZERO_RANGE|FALLOC_FL_KEEP_SIZE, 
>>> offset, len);
>>> +
>>> +    if (n < 0)
>>> +        return -errno;
>>> +    return n;
>>> +}
>>> +
>>>   int os_eventfd(unsigned int initval, int flags)
>>>   {
>>>       int fd = eventfd(initval, flags);
>>>
>>
>> Acked-by: Anton Ivanov <anton.ivanov at cambridgegreys.com>
>>
> What should be next step to get this merged?

I reviewed it and acked it.

Richard decides which on the actual merge.

A.

> 
> Regards,
> 
> Fred
> 

-- 
Anton R. Ivanov
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https://www.cambridgegreys.com/