[v2,2/2] libceph: just wait for more data to be available on the socket

Commit Message

Xiubo Li Dec. 8, 2023, 4:06 p.m. UTC

From: Xiubo Li <[e-mail]>

The messages from ceph maybe split into multiple socket packages
and we just need to wait for all the data to be availiable on the
sokcet.

This will add a new _FINISH state for the sparse-read to mark the
current sparse-read succeeded. Else it will treat it as a new
sparse-read when the socket receives the last piece of the osd
request reply message, and the cancel_request() later will help
init the sparse-read context.

URL: https://tracker.ceph.com/issues/63586
Signed-off-by: Xiubo Li <[e-mail]>
---
 include/linux/ceph/osd_client.h | 1 +
 net/ceph/osd_client.c           | 6 +++---
 2 files changed, 4 insertions(+), 3 deletions(-)

Comments

Ilya Dryomov Dec. 12, 2023, 4:31 p.m. UTC | #1

On Fri, Dec 8, 2023 at 5:08 PM <[e-mail]> wrote:
>
> From: Xiubo Li <[e-mail]>
>
> The messages from ceph maybe split into multiple socket packages
> and we just need to wait for all the data to be availiable on the
> sokcet.
>
> This will add a new _FINISH state for the sparse-read to mark the
> current sparse-read succeeded. Else it will treat it as a new
> sparse-read when the socket receives the last piece of the osd
> request reply message, and the cancel_request() later will help
> init the sparse-read context.
>
> URL: https://tracker.ceph.com/issues/63586
> Signed-off-by: Xiubo Li <[e-mail]>
> ---
>  include/linux/ceph/osd_client.h | 1 +
>  net/ceph/osd_client.c           | 6 +++---
>  2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> index 493de3496cd3..00d98e13100f 100644
> --- a/include/linux/ceph/osd_client.h
> +++ b/include/linux/ceph/osd_client.h
> @@ -47,6 +47,7 @@ enum ceph_sparse_read_state {
>         CEPH_SPARSE_READ_DATA_LEN,
>         CEPH_SPARSE_READ_DATA_PRE,
>         CEPH_SPARSE_READ_DATA,
> +       CEPH_SPARSE_READ_FINISH,
>  };
>
>  /*
> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> index 848ef19055a0..f1705b4f19eb 100644
> --- a/net/ceph/osd_client.c
> +++ b/net/ceph/osd_client.c
> @@ -5802,8 +5802,6 @@ static int prep_next_sparse_read(struct ceph_connection *con,
>                         advance_cursor(cursor, sr->sr_req_len - end, false);
>         }
>
> -       ceph_init_sparse_read(sr);
> -
>         /* find next op in this request (if any) */
>         while (++o->o_sparse_op_idx < req->r_num_ops) {
>                 op = &req->r_ops[o->o_sparse_op_idx];
> @@ -5919,7 +5917,7 @@ static int osd_sparse_read(struct ceph_connection *con,
>                                 return -EREMOTEIO;
>                         }
>
> -                       sr->sr_state = CEPH_SPARSE_READ_HDR;
> +                       sr->sr_state = CEPH_SPARSE_READ_FINISH;
>                         goto next_op;

Hi Xiubo,

This code appears to be set up to handle multiple (sparse-read) ops in
a single OSD request.  Wouldn't this break that case?

I think the bug is in read_sparse_msg_data().  It shouldn't be calling
con->ops->sparse_read() after the message has progressed to the footer.
osd_sparse_read() is most likely fine as is.

Notice how read_partial_msg_data() and read_partial_msg_data_bounce()
behave: if called at that point (i.e. after the data section has been
processed, meaning that cursor->total_resid == 0), they do nothing.
read_sparse_msg_data() should have a similar condition and basically
no-op itself.

While at it, let's rename it to read_partial_sparse_msg_data() to
emphasize the "partial"/no-op semantics that are required there.

Thanks,

                Ilya

Xiubo Li Dec. 13, 2023, 1:01 a.m. UTC | #2

On 12/13/23 00:31, Ilya Dryomov wrote:
> On Fri, Dec 8, 2023 at 5:08 PM <[e-mail]> wrote:
>> From: Xiubo Li <[e-mail]>
>>
>> The messages from ceph maybe split into multiple socket packages
>> and we just need to wait for all the data to be availiable on the
>> sokcet.
>>
>> This will add a new _FINISH state for the sparse-read to mark the
>> current sparse-read succeeded. Else it will treat it as a new
>> sparse-read when the socket receives the last piece of the osd
>> request reply message, and the cancel_request() later will help
>> init the sparse-read context.
>>
>> URL: https://tracker.ceph.com/issues/63586
>> Signed-off-by: Xiubo Li <[e-mail]>
>> ---
>>   include/linux/ceph/osd_client.h | 1 +
>>   net/ceph/osd_client.c           | 6 +++---
>>   2 files changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
>> index 493de3496cd3..00d98e13100f 100644
>> --- a/include/linux/ceph/osd_client.h
>> +++ b/include/linux/ceph/osd_client.h
>> @@ -47,6 +47,7 @@ enum ceph_sparse_read_state {
>>          CEPH_SPARSE_READ_DATA_LEN,
>>          CEPH_SPARSE_READ_DATA_PRE,
>>          CEPH_SPARSE_READ_DATA,
>> +       CEPH_SPARSE_READ_FINISH,
>>   };
>>
>>   /*
>> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
>> index 848ef19055a0..f1705b4f19eb 100644
>> --- a/net/ceph/osd_client.c
>> +++ b/net/ceph/osd_client.c
>> @@ -5802,8 +5802,6 @@ static int prep_next_sparse_read(struct ceph_connection *con,
>>                          advance_cursor(cursor, sr->sr_req_len - end, false);
>>          }
>>
>> -       ceph_init_sparse_read(sr);
>> -
>>          /* find next op in this request (if any) */
>>          while (++o->o_sparse_op_idx < req->r_num_ops) {
>>                  op = &req->r_ops[o->o_sparse_op_idx];
>> @@ -5919,7 +5917,7 @@ static int osd_sparse_read(struct ceph_connection *con,
>>                                  return -EREMOTEIO;
>>                          }
>>
>> -                       sr->sr_state = CEPH_SPARSE_READ_HDR;
>> +                       sr->sr_state = CEPH_SPARSE_READ_FINISH;
>>                          goto next_op;
> Hi Xiubo,
>
> This code appears to be set up to handle multiple (sparse-read) ops in
> a single OSD request.  Wouldn't this break that case?

Yeah, it will break it. I just missed it.

> I think the bug is in read_sparse_msg_data().  It shouldn't be calling
> con->ops->sparse_read() after the message has progressed to the footer.
> osd_sparse_read() is most likely fine as is.

Yes it is. We cannot tell exactly whether has it progressed to the 
footer IMO, such as when in case 'con->v1.in_base_pos == 
sizeof(con->v1.in_hdr)' the socket buffer may break just after finishing 
sparse-read and before reading footer or some where in sparse-read. For 
the later case then we should continue in the sparse reads.


> Notice how read_partial_msg_data() and read_partial_msg_data_bounce()
> behave: if called at that point (i.e. after the data section has been
> processed, meaning that cursor->total_resid == 0), they do nothing.
> read_sparse_msg_data() should have a similar condition and basically
> no-op itself.

Correct, this what I want to do in the sparse-read code.

>
> While at it, let's rename it to read_partial_sparse_msg_data() to
> emphasize the "partial"/no-op semantics that are required there.

Sure.

Thanks

- Xiubo


> Thanks,
>
>                  Ilya
>

Xiubo Li Dec. 13, 2023, 1:13 a.m. UTC | #3

Hi Ilya,

I just fixed it and it will be something like this below, I haven't 
tested it yet because I am running other tests locally.

This time it will set the state to 'CEPH_SPARSE_READ_FINISH' when the 
last sparse-read op is successfully read.

diff --git a/include/linux/ceph/osd_client.h 
b/include/linux/ceph/osd_client.h
index 493de3496cd3..00d98e13100f 100644
--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -47,6 +47,7 @@ enum ceph_sparse_read_state {
         CEPH_SPARSE_READ_DATA_LEN,
         CEPH_SPARSE_READ_DATA_PRE,
         CEPH_SPARSE_READ_DATA,
+       CEPH_SPARSE_READ_FINISH,
  };

  /*
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 848ef19055a0..b3b61f010428 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -5813,6 +5813,7 @@ static int prep_next_sparse_read(struct 
ceph_connection *con,

         /* reset for next sparse read request */
         spin_unlock(&o->o_requests_lock);
+       sr->sr_state = CEPH_SPARSE_READ_FINISH;
         o->o_sparse_op_idx = -1;
         return 0;
  found:
@@ -5918,8 +5919,6 @@ static int osd_sparse_read(struct ceph_connection 
*con,
                                                     count);
                                 return -EREMOTEIO;
                         }
-
-                       sr->sr_state = CEPH_SPARSE_READ_HDR;
                         goto next_op;
                 }

@@ -5952,6 +5951,8 @@ static int osd_sparse_read(struct ceph_connection 
*con,
                 /* Bump the array index */
                 ++sr->sr_index;
                 break;
+       case CEPH_SPARSE_READ_FINISH:
+               return 0;
         }
         return ret;
  }

I will send out the V3 after my testing.


Jeff,

Could you help review it, want to make sure that it won't break anything 
here for sparse read.


Thanks

- Xiubo


On 12/13/23 00:31, Ilya Dryomov wrote:
> On Fri, Dec 8, 2023 at 5:08 PM <[e-mail]> wrote:
>> From: Xiubo Li <[e-mail]>
>>
>> The messages from ceph maybe split into multiple socket packages
>> and we just need to wait for all the data to be availiable on the
>> sokcet.
>>
>> This will add a new _FINISH state for the sparse-read to mark the
>> current sparse-read succeeded. Else it will treat it as a new
>> sparse-read when the socket receives the last piece of the osd
>> request reply message, and the cancel_request() later will help
>> init the sparse-read context.
>>
>> URL: https://tracker.ceph.com/issues/63586
>> Signed-off-by: Xiubo Li <[e-mail]>
>> ---
>>   include/linux/ceph/osd_client.h | 1 +
>>   net/ceph/osd_client.c           | 6 +++---
>>   2 files changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
>> index 493de3496cd3..00d98e13100f 100644
>> --- a/include/linux/ceph/osd_client.h
>> +++ b/include/linux/ceph/osd_client.h
>> @@ -47,6 +47,7 @@ enum ceph_sparse_read_state {
>>          CEPH_SPARSE_READ_DATA_LEN,
>>          CEPH_SPARSE_READ_DATA_PRE,
>>          CEPH_SPARSE_READ_DATA,
>> +       CEPH_SPARSE_READ_FINISH,
>>   };
>>
>>   /*
>> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
>> index 848ef19055a0..f1705b4f19eb 100644
>> --- a/net/ceph/osd_client.c
>> +++ b/net/ceph/osd_client.c
>> @@ -5802,8 +5802,6 @@ static int prep_next_sparse_read(struct ceph_connection *con,
>>                          advance_cursor(cursor, sr->sr_req_len - end, false);
>>          }
>>
>> -       ceph_init_sparse_read(sr);
>> -
>>          /* find next op in this request (if any) */
>>          while (++o->o_sparse_op_idx < req->r_num_ops) {
>>                  op = &req->r_ops[o->o_sparse_op_idx];
>> @@ -5919,7 +5917,7 @@ static int osd_sparse_read(struct ceph_connection *con,
>>                                  return -EREMOTEIO;
>>                          }
>>
>> -                       sr->sr_state = CEPH_SPARSE_READ_HDR;
>> +                       sr->sr_state = CEPH_SPARSE_READ_FINISH;
>>                          goto next_op;
> Hi Xiubo,
>
> This code appears to be set up to handle multiple (sparse-read) ops in
> a single OSD request.  Wouldn't this break that case?
>
> I think the bug is in read_sparse_msg_data().  It shouldn't be calling
> con->ops->sparse_read() after the message has progressed to the footer.
> osd_sparse_read() is most likely fine as is.
>
> Notice how read_partial_msg_data() and read_partial_msg_data_bounce()
> behave: if called at that point (i.e. after the data section has been
> processed, meaning that cursor->total_resid == 0), they do nothing.
> read_sparse_msg_data() should have a similar condition and basically
> no-op itself.
>
> While at it, let's rename it to read_partial_sparse_msg_data() to
> emphasize the "partial"/no-op semantics that are required there.
>
> Thanks,
>
>                  Ilya
>

Ilya Dryomov Dec. 13, 2023, 10:31 a.m. UTC | #4

On Wed, Dec 13, 2023 at 2:02 AM Xiubo Li <[e-mail]> wrote:
>
>
> On 12/13/23 00:31, Ilya Dryomov wrote:
> > On Fri, Dec 8, 2023 at 5:08 PM <[e-mail]> wrote:
> >> From: Xiubo Li <[e-mail]>
> >>
> >> The messages from ceph maybe split into multiple socket packages
> >> and we just need to wait for all the data to be availiable on the
> >> sokcet.
> >>
> >> This will add a new _FINISH state for the sparse-read to mark the
> >> current sparse-read succeeded. Else it will treat it as a new
> >> sparse-read when the socket receives the last piece of the osd
> >> request reply message, and the cancel_request() later will help
> >> init the sparse-read context.
> >>
> >> URL: https://tracker.ceph.com/issues/63586
> >> Signed-off-by: Xiubo Li <[e-mail]>
> >> ---
> >>   include/linux/ceph/osd_client.h | 1 +
> >>   net/ceph/osd_client.c           | 6 +++---
> >>   2 files changed, 4 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> >> index 493de3496cd3..00d98e13100f 100644
> >> --- a/include/linux/ceph/osd_client.h
> >> +++ b/include/linux/ceph/osd_client.h
> >> @@ -47,6 +47,7 @@ enum ceph_sparse_read_state {
> >>          CEPH_SPARSE_READ_DATA_LEN,
> >>          CEPH_SPARSE_READ_DATA_PRE,
> >>          CEPH_SPARSE_READ_DATA,
> >> +       CEPH_SPARSE_READ_FINISH,
> >>   };
> >>
> >>   /*
> >> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> >> index 848ef19055a0..f1705b4f19eb 100644
> >> --- a/net/ceph/osd_client.c
> >> +++ b/net/ceph/osd_client.c
> >> @@ -5802,8 +5802,6 @@ static int prep_next_sparse_read(struct ceph_connection *con,
> >>                          advance_cursor(cursor, sr->sr_req_len - end, false);
> >>          }
> >>
> >> -       ceph_init_sparse_read(sr);
> >> -
> >>          /* find next op in this request (if any) */
> >>          while (++o->o_sparse_op_idx < req->r_num_ops) {
> >>                  op = &req->r_ops[o->o_sparse_op_idx];
> >> @@ -5919,7 +5917,7 @@ static int osd_sparse_read(struct ceph_connection *con,
> >>                                  return -EREMOTEIO;
> >>                          }
> >>
> >> -                       sr->sr_state = CEPH_SPARSE_READ_HDR;
> >> +                       sr->sr_state = CEPH_SPARSE_READ_FINISH;
> >>                          goto next_op;
> > Hi Xiubo,
> >
> > This code appears to be set up to handle multiple (sparse-read) ops in
> > a single OSD request.  Wouldn't this break that case?
>
> Yeah, it will break it. I just missed it.
>
> > I think the bug is in read_sparse_msg_data().  It shouldn't be calling
> > con->ops->sparse_read() after the message has progressed to the footer.
> > osd_sparse_read() is most likely fine as is.
>
> Yes it is. We cannot tell exactly whether has it progressed to the
> footer IMO, such as when in case 'con->v1.in_base_pos ==

Hi Xiubo,

I don't buy this.  If the messenger is trying to read the footer, it
_has_ progressed to the footer.  This is definitive and irreversible,
not a "maybe".

> sizeof(con->v1.in_hdr)' the socket buffer may break just after finishing
> sparse-read and before reading footer or some where in sparse-read. For
> the later case then we should continue in the sparse reads.

The size of the data section of the message is always known.  The
contract is that read_partial_msg_data*() returns 1 and does nothing
else after the data section is consumed.  This is how the messenger is
told to move on to the footer.

read_partial_sparse_msg_data() doesn't adhere to this contract and
should be fixed.

>
>
> > Notice how read_partial_msg_data() and read_partial_msg_data_bounce()
> > behave: if called at that point (i.e. after the data section has been
> > processed, meaning that cursor->total_resid == 0), they do nothing.
> > read_sparse_msg_data() should have a similar condition and basically
> > no-op itself.
>
> Correct, this what I want to do in the sparse-read code.

No, this needs to be done on the messenger side.  sparse-read code
should not be invoked after the messenger has moved on to the footer.

Thanks,

                Ilya

Xiubo Li Dec. 13, 2023, 11:03 a.m. UTC | #5

On 12/13/23 18:31, Ilya Dryomov wrote:
> On Wed, Dec 13, 2023 at 2:02 AM Xiubo Li <[e-mail]> wrote:
>>
>> On 12/13/23 00:31, Ilya Dryomov wrote:
>>> On Fri, Dec 8, 2023 at 5:08 PM <[e-mail]> wrote:
>>>> From: Xiubo Li <[e-mail]>
>>>>
>>>> The messages from ceph maybe split into multiple socket packages
>>>> and we just need to wait for all the data to be availiable on the
>>>> sokcet.
>>>>
>>>> This will add a new _FINISH state for the sparse-read to mark the
>>>> current sparse-read succeeded. Else it will treat it as a new
>>>> sparse-read when the socket receives the last piece of the osd
>>>> request reply message, and the cancel_request() later will help
>>>> init the sparse-read context.
>>>>
>>>> URL: https://tracker.ceph.com/issues/63586
>>>> Signed-off-by: Xiubo Li <[e-mail]>
>>>> ---
>>>>    include/linux/ceph/osd_client.h | 1 +
>>>>    net/ceph/osd_client.c           | 6 +++---
>>>>    2 files changed, 4 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
>>>> index 493de3496cd3..00d98e13100f 100644
>>>> --- a/include/linux/ceph/osd_client.h
>>>> +++ b/include/linux/ceph/osd_client.h
>>>> @@ -47,6 +47,7 @@ enum ceph_sparse_read_state {
>>>>           CEPH_SPARSE_READ_DATA_LEN,
>>>>           CEPH_SPARSE_READ_DATA_PRE,
>>>>           CEPH_SPARSE_READ_DATA,
>>>> +       CEPH_SPARSE_READ_FINISH,
>>>>    };
>>>>
>>>>    /*
>>>> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
>>>> index 848ef19055a0..f1705b4f19eb 100644
>>>> --- a/net/ceph/osd_client.c
>>>> +++ b/net/ceph/osd_client.c
>>>> @@ -5802,8 +5802,6 @@ static int prep_next_sparse_read(struct ceph_connection *con,
>>>>                           advance_cursor(cursor, sr->sr_req_len - end, false);
>>>>           }
>>>>
>>>> -       ceph_init_sparse_read(sr);
>>>> -
>>>>           /* find next op in this request (if any) */
>>>>           while (++o->o_sparse_op_idx < req->r_num_ops) {
>>>>                   op = &req->r_ops[o->o_sparse_op_idx];
>>>> @@ -5919,7 +5917,7 @@ static int osd_sparse_read(struct ceph_connection *con,
>>>>                                   return -EREMOTEIO;
>>>>                           }
>>>>
>>>> -                       sr->sr_state = CEPH_SPARSE_READ_HDR;
>>>> +                       sr->sr_state = CEPH_SPARSE_READ_FINISH;
>>>>                           goto next_op;
>>> Hi Xiubo,
>>>
>>> This code appears to be set up to handle multiple (sparse-read) ops in
>>> a single OSD request.  Wouldn't this break that case?
>> Yeah, it will break it. I just missed it.
>>
>>> I think the bug is in read_sparse_msg_data().  It shouldn't be calling
>>> con->ops->sparse_read() after the message has progressed to the footer.
>>> osd_sparse_read() is most likely fine as is.
>> Yes it is. We cannot tell exactly whether has it progressed to the
>> footer IMO, such as when in case 'con->v1.in_base_pos ==
> Hi Xiubo,
>
> I don't buy this.  If the messenger is trying to read the footer, it
> _has_ progressed to the footer.  This is definitive and irreversible,
> not a "maybe".
>
>> sizeof(con->v1.in_hdr)' the socket buffer may break just after finishing
>> sparse-read and before reading footer or some where in sparse-read. For
>> the later case then we should continue in the sparse reads.
> The size of the data section of the message is always known.  The
> contract is that read_partial_msg_data*() returns 1 and does nothing
> else after the data section is consumed.  This is how the messenger is
> told to move on to the footer.
>
> read_partial_sparse_msg_data() doesn't adhere to this contract and
> should be fixed.
>
>>
>>> Notice how read_partial_msg_data() and read_partial_msg_data_bounce()
>>> behave: if called at that point (i.e. after the data section has been
>>> processed, meaning that cursor->total_resid == 0), they do nothing.
>>> read_sparse_msg_data() should have a similar condition and basically
>>> no-op itself.
>> Correct, this what I want to do in the sparse-read code.
> No, this needs to be done on the messenger side.  sparse-read code
> should not be invoked after the messenger has moved on to the footer.

 From my reading, even the messenger has moved on to the 'footer', it 
will always try to invoke to parse the 'header':

read_partial(con, end, size, &con->v1.in_hdr);

But it will do nothing and just returns.

And the same for 'front', 'middle' and '(page) data', then the last for 
'footer'.

Did I miss something ?

Thanks

- Xiubo

> Thanks,
>
>                  Ilya
>

Ilya Dryomov Dec. 13, 2023, 11:54 a.m. UTC | #6

On Wed, Dec 13, 2023 at 12:03 PM Xiubo Li <[e-mail]> wrote:
>
>
> On 12/13/23 18:31, Ilya Dryomov wrote:
> > On Wed, Dec 13, 2023 at 2:02 AM Xiubo Li <[e-mail]> wrote:
> >>
> >> On 12/13/23 00:31, Ilya Dryomov wrote:
> >>> On Fri, Dec 8, 2023 at 5:08 PM <[e-mail]> wrote:
> >>>> From: Xiubo Li <[e-mail]>
> >>>>
> >>>> The messages from ceph maybe split into multiple socket packages
> >>>> and we just need to wait for all the data to be availiable on the
> >>>> sokcet.
> >>>>
> >>>> This will add a new _FINISH state for the sparse-read to mark the
> >>>> current sparse-read succeeded. Else it will treat it as a new
> >>>> sparse-read when the socket receives the last piece of the osd
> >>>> request reply message, and the cancel_request() later will help
> >>>> init the sparse-read context.
> >>>>
> >>>> URL: https://tracker.ceph.com/issues/63586
> >>>> Signed-off-by: Xiubo Li <[e-mail]>
> >>>> ---
> >>>>    include/linux/ceph/osd_client.h | 1 +
> >>>>    net/ceph/osd_client.c           | 6 +++---
> >>>>    2 files changed, 4 insertions(+), 3 deletions(-)
> >>>>
> >>>> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> >>>> index 493de3496cd3..00d98e13100f 100644
> >>>> --- a/include/linux/ceph/osd_client.h
> >>>> +++ b/include/linux/ceph/osd_client.h
> >>>> @@ -47,6 +47,7 @@ enum ceph_sparse_read_state {
> >>>>           CEPH_SPARSE_READ_DATA_LEN,
> >>>>           CEPH_SPARSE_READ_DATA_PRE,
> >>>>           CEPH_SPARSE_READ_DATA,
> >>>> +       CEPH_SPARSE_READ_FINISH,
> >>>>    };
> >>>>
> >>>>    /*
> >>>> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> >>>> index 848ef19055a0..f1705b4f19eb 100644
> >>>> --- a/net/ceph/osd_client.c
> >>>> +++ b/net/ceph/osd_client.c
> >>>> @@ -5802,8 +5802,6 @@ static int prep_next_sparse_read(struct ceph_connection *con,
> >>>>                           advance_cursor(cursor, sr->sr_req_len - end, false);
> >>>>           }
> >>>>
> >>>> -       ceph_init_sparse_read(sr);
> >>>> -
> >>>>           /* find next op in this request (if any) */
> >>>>           while (++o->o_sparse_op_idx < req->r_num_ops) {
> >>>>                   op = &req->r_ops[o->o_sparse_op_idx];
> >>>> @@ -5919,7 +5917,7 @@ static int osd_sparse_read(struct ceph_connection *con,
> >>>>                                   return -EREMOTEIO;
> >>>>                           }
> >>>>
> >>>> -                       sr->sr_state = CEPH_SPARSE_READ_HDR;
> >>>> +                       sr->sr_state = CEPH_SPARSE_READ_FINISH;
> >>>>                           goto next_op;
> >>> Hi Xiubo,
> >>>
> >>> This code appears to be set up to handle multiple (sparse-read) ops in
> >>> a single OSD request.  Wouldn't this break that case?
> >> Yeah, it will break it. I just missed it.
> >>
> >>> I think the bug is in read_sparse_msg_data().  It shouldn't be calling
> >>> con->ops->sparse_read() after the message has progressed to the footer.
> >>> osd_sparse_read() is most likely fine as is.
> >> Yes it is. We cannot tell exactly whether has it progressed to the
> >> footer IMO, such as when in case 'con->v1.in_base_pos ==
> > Hi Xiubo,
> >
> > I don't buy this.  If the messenger is trying to read the footer, it
> > _has_ progressed to the footer.  This is definitive and irreversible,
> > not a "maybe".
> >
> >> sizeof(con->v1.in_hdr)' the socket buffer may break just after finishing
> >> sparse-read and before reading footer or some where in sparse-read. For
> >> the later case then we should continue in the sparse reads.
> > The size of the data section of the message is always known.  The
> > contract is that read_partial_msg_data*() returns 1 and does nothing
> > else after the data section is consumed.  This is how the messenger is
> > told to move on to the footer.
> >
> > read_partial_sparse_msg_data() doesn't adhere to this contract and
> > should be fixed.
> >
> >>
> >>> Notice how read_partial_msg_data() and read_partial_msg_data_bounce()
> >>> behave: if called at that point (i.e. after the data section has been
> >>> processed, meaning that cursor->total_resid == 0), they do nothing.
> >>> read_sparse_msg_data() should have a similar condition and basically
> >>> no-op itself.
> >> Correct, this what I want to do in the sparse-read code.
> > No, this needs to be done on the messenger side.  sparse-read code
> > should not be invoked after the messenger has moved on to the footer.
>
>  From my reading, even the messenger has moved on to the 'footer', it
> will always try to invoke to parse the 'header':
>
> read_partial(con, end, size, &con->v1.in_hdr);
>
> But it will do nothing and just returns.
>
> And the same for 'front', 'middle' and '(page) data', then the last for
> 'footer'.

This is correct.

>
> Did I miss something ?

No, it's how the messenger is set up to work.  The problem is that
read_sparse_msg_data() doesn't fit this model, so it should be fixed
and renamed to read_partial_sparse_msg_data().

Thanks,

                Ilya

Ilya Dryomov Dec. 13, 2023, 1:07 p.m. UTC | #7

On Wed, Dec 13, 2023 at 1:05 PM Xiubo Li <[e-mail]> wrote:
>
>
> On 12/13/23 19:54, Ilya Dryomov wrote:
>
> On Wed, Dec 13, 2023 at 12:03 PM Xiubo Li <[e-mail]> wrote:
>
> On 12/13/23 18:31, Ilya Dryomov wrote:
>
> On Wed, Dec 13, 2023 at 2:02 AM Xiubo Li <[e-mail]> wrote:
>
> On 12/13/23 00:31, Ilya Dryomov wrote:
>
> On Fri, Dec 8, 2023 at 5:08 PM <[e-mail]> wrote:
>
> From: Xiubo Li <[e-mail]>
>
> The messages from ceph maybe split into multiple socket packages
> and we just need to wait for all the data to be availiable on the
> sokcet.
>
> This will add a new _FINISH state for the sparse-read to mark the
> current sparse-read succeeded. Else it will treat it as a new
> sparse-read when the socket receives the last piece of the osd
> request reply message, and the cancel_request() later will help
> init the sparse-read context.
>
> URL: https://tracker.ceph.com/issues/63586
> Signed-off-by: Xiubo Li <[e-mail]>
> ---
>    include/linux/ceph/osd_client.h | 1 +
>    net/ceph/osd_client.c           | 6 +++---
>    2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> index 493de3496cd3..00d98e13100f 100644
> --- a/include/linux/ceph/osd_client.h
> +++ b/include/linux/ceph/osd_client.h
> @@ -47,6 +47,7 @@ enum ceph_sparse_read_state {
>           CEPH_SPARSE_READ_DATA_LEN,
>           CEPH_SPARSE_READ_DATA_PRE,
>           CEPH_SPARSE_READ_DATA,
> +       CEPH_SPARSE_READ_FINISH,
>    };
>
>    /*
> diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> index 848ef19055a0..f1705b4f19eb 100644
> --- a/net/ceph/osd_client.c
> +++ b/net/ceph/osd_client.c
> @@ -5802,8 +5802,6 @@ static int prep_next_sparse_read(struct ceph_connection *con,
>                           advance_cursor(cursor, sr->sr_req_len - end, false);
>           }
>
> -       ceph_init_sparse_read(sr);
> -
>           /* find next op in this request (if any) */
>           while (++o->o_sparse_op_idx < req->r_num_ops) {
>                   op = &req->r_ops[o->o_sparse_op_idx];
> @@ -5919,7 +5917,7 @@ static int osd_sparse_read(struct ceph_connection *con,
>                                   return -EREMOTEIO;
>                           }
>
> -                       sr->sr_state = CEPH_SPARSE_READ_HDR;
> +                       sr->sr_state = CEPH_SPARSE_READ_FINISH;
>                           goto next_op;
>
> Hi Xiubo,
>
> This code appears to be set up to handle multiple (sparse-read) ops in
> a single OSD request.  Wouldn't this break that case?
>
> Yeah, it will break it. I just missed it.
>
> I think the bug is in read_sparse_msg_data().  It shouldn't be calling
> con->ops->sparse_read() after the message has progressed to the footer.
> osd_sparse_read() is most likely fine as is.
>
> Yes it is. We cannot tell exactly whether has it progressed to the
> footer IMO, such as when in case 'con->v1.in_base_pos ==
>
> Hi Xiubo,
>
> I don't buy this.  If the messenger is trying to read the footer, it
> _has_ progressed to the footer.  This is definitive and irreversible,
> not a "maybe".
>
> sizeof(con->v1.in_hdr)' the socket buffer may break just after finishing
> sparse-read and before reading footer or some where in sparse-read. For
> the later case then we should continue in the sparse reads.
>
> The size of the data section of the message is always known.  The
> contract is that read_partial_msg_data*() returns 1 and does nothing
> else after the data section is consumed.  This is how the messenger is
> told to move on to the footer.
>
> read_partial_sparse_msg_data() doesn't adhere to this contract and
> should be fixed.
>
> Notice how read_partial_msg_data() and read_partial_msg_data_bounce()
> behave: if called at that point (i.e. after the data section has been
> processed, meaning that cursor->total_resid == 0), they do nothing.
> read_sparse_msg_data() should have a similar condition and basically
> no-op itself.
>
> Correct, this what I want to do in the sparse-read code.
>
> No, this needs to be done on the messenger side.  sparse-read code
> should not be invoked after the messenger has moved on to the footer.
>
>  From my reading, even the messenger has moved on to the 'footer', it
> will always try to invoke to parse the 'header':
>
> read_partial(con, end, size, &con->v1.in_hdr);
>
> But it will do nothing and just returns.
>
> And the same for 'front', 'middle' and '(page) data', then the last for
> 'footer'.
>
> This is correct.
>
> Did I miss something ?
>
> No, it's how the messenger is set up to work.  The problem is that
> read_sparse_msg_data() doesn't fit this model, so it should be fixed
> and renamed to read_partial_sparse_msg_data().
>
> Okay, let me try.
>
> Did you see my new patch in last mail ? Will that work ?
>
> If not I will try to fix it in read_partial_sparse_msg_data().

It might work around the problem, but it's not the right fix.  Think
about it: what business does code in the OSD client have being called
when the messenger is 14 bytes into reading the footer (number taken
from the log in the cover letter)?  All data is read at that point and
the last op in a multi-op OSD request may not even be sparse-read...

Thanks,

                Ilya

Jeffrey Layton Dec. 13, 2023, 2:11 p.m. UTC | #8

On Wed, 2023-12-13 at 14:07 +0100, Ilya Dryomov wrote:
> On Wed, Dec 13, 2023 at 1:05 PM Xiubo Li <[e-mail]> wrote:
> > 
> > 
> > On 12/13/23 19:54, Ilya Dryomov wrote:
> > 
> > On Wed, Dec 13, 2023 at 12:03 PM Xiubo Li <[e-mail]> wrote:
> > 
> > On 12/13/23 18:31, Ilya Dryomov wrote:
> > 
> > On Wed, Dec 13, 2023 at 2:02 AM Xiubo Li <[e-mail]> wrote:
> > 
> > On 12/13/23 00:31, Ilya Dryomov wrote:
> > 
> > On Fri, Dec 8, 2023 at 5:08 PM <[e-mail]> wrote:
> > 
> > From: Xiubo Li <[e-mail]>
> > 
> > The messages from ceph maybe split into multiple socket packages
> > and we just need to wait for all the data to be availiable on the
> > sokcet.
> > 
> > This will add a new _FINISH state for the sparse-read to mark the
> > current sparse-read succeeded. Else it will treat it as a new
> > sparse-read when the socket receives the last piece of the osd
> > request reply message, and the cancel_request() later will help
> > init the sparse-read context.
> > 
> > URL: https://tracker.ceph.com/issues/63586
> > Signed-off-by: Xiubo Li <[e-mail]>
> > ---
> >    include/linux/ceph/osd_client.h | 1 +
> >    net/ceph/osd_client.c           | 6 +++---
> >    2 files changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> > index 493de3496cd3..00d98e13100f 100644
> > --- a/include/linux/ceph/osd_client.h
> > +++ b/include/linux/ceph/osd_client.h
> > @@ -47,6 +47,7 @@ enum ceph_sparse_read_state {
> >           CEPH_SPARSE_READ_DATA_LEN,
> >           CEPH_SPARSE_READ_DATA_PRE,
> >           CEPH_SPARSE_READ_DATA,
> > +       CEPH_SPARSE_READ_FINISH,
> >    };
> > 
> >    /*
> > diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
> > index 848ef19055a0..f1705b4f19eb 100644
> > --- a/net/ceph/osd_client.c
> > +++ b/net/ceph/osd_client.c
> > @@ -5802,8 +5802,6 @@ static int prep_next_sparse_read(struct ceph_connection *con,
> >                           advance_cursor(cursor, sr->sr_req_len - end, false);
> >           }
> > 
> > -       ceph_init_sparse_read(sr);
> > -
> >           /* find next op in this request (if any) */
> >           while (++o->o_sparse_op_idx < req->r_num_ops) {
> >                   op = &req->r_ops[o->o_sparse_op_idx];
> > @@ -5919,7 +5917,7 @@ static int osd_sparse_read(struct ceph_connection *con,
> >                                   return -EREMOTEIO;
> >                           }
> > 
> > -                       sr->sr_state = CEPH_SPARSE_READ_HDR;
> > +                       sr->sr_state = CEPH_SPARSE_READ_FINISH;
> >                           goto next_op;
> > 
> > Hi Xiubo,
> > 
> > This code appears to be set up to handle multiple (sparse-read) ops in
> > a single OSD request.  Wouldn't this break that case?
> > 
> > Yeah, it will break it. I just missed it.
> > 
> > I think the bug is in read_sparse_msg_data().  It shouldn't be calling
> > con->ops->sparse_read() after the message has progressed to the footer.
> > osd_sparse_read() is most likely fine as is.
> > 
> > Yes it is. We cannot tell exactly whether has it progressed to the
> > footer IMO, such as when in case 'con->v1.in_base_pos ==
> > 
> > Hi Xiubo,
> > 
> > I don't buy this.  If the messenger is trying to read the footer, it
> > _has_ progressed to the footer.  This is definitive and irreversible,
> > not a "maybe".
> > 
> > sizeof(con->v1.in_hdr)' the socket buffer may break just after finishing
> > sparse-read and before reading footer or some where in sparse-read. For
> > the later case then we should continue in the sparse reads.
> > 
> > The size of the data section of the message is always known.  The
> > contract is that read_partial_msg_data*() returns 1 and does nothing
> > else after the data section is consumed.  This is how the messenger is
> > told to move on to the footer.
> > 
> > read_partial_sparse_msg_data() doesn't adhere to this contract and
> > should be fixed.
> > 
> > Notice how read_partial_msg_data() and read_partial_msg_data_bounce()
> > behave: if called at that point (i.e. after the data section has been
> > processed, meaning that cursor->total_resid == 0), they do nothing.
> > read_sparse_msg_data() should have a similar condition and basically
> > no-op itself.
> > 
> > Correct, this what I want to do in the sparse-read code.
> > 
> > No, this needs to be done on the messenger side.  sparse-read code
> > should not be invoked after the messenger has moved on to the footer.
> > 
> >  From my reading, even the messenger has moved on to the 'footer', it
> > will always try to invoke to parse the 'header':
> > 
> > read_partial(con, end, size, &con->v1.in_hdr);
> > 
> > But it will do nothing and just returns.
> > 
> > And the same for 'front', 'middle' and '(page) data', then the last for
> > 'footer'.
> > 
> > This is correct.
> > 
> > Did I miss something ?
> > 
> > No, it's how the messenger is set up to work.  The problem is that
> > read_sparse_msg_data() doesn't fit this model, so it should be fixed
> > and renamed to read_partial_sparse_msg_data().
> > 
> > Okay, let me try.
> > 
> > Did you see my new patch in last mail ? Will that work ?
> > 
> > If not I will try to fix it in read_partial_sparse_msg_data().
> 
> It might work around the problem, but it's not the right fix.  Think
> about it: what business does code in the OSD client have being called
> when the messenger is 14 bytes into reading the footer (number taken
> from the log in the cover letter)?  All data is read at that point and
> the last op in a multi-op OSD request may not even be sparse-read...
> 

The assumption in ceph_osdc_new_request is that if you have a multi-op
request, that they are either all reads or all writes. The assumption
about writes has been there a long time. I simply added the ability to
do the same for reads:

    4e8c4c235578 libceph: allow ceph_osdc_new_request to accept a multi-op read

Note that we do this in ceph_sync_write in the rmw case, so that does
need to keep working.

Technically we could have a normal read in the same request as a sparse
read but I figured that would be a little silly. That's why it tries to
prep a second sparse read once the first is done. If there isn't one
then that should fall through to the return 0 just before the "found:"
label in prep_next_sparse_read.

So, I tend to agree with Ilya that the problem isn't down in the OSD
state machine, but more likely at the receive handling layer. It's
certainly plausible that I didn't get the handling of short receives
right (particularly in the messenger_v1 part).

Patch

diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
index 493de3496cd3..00d98e13100f 100644
--- a/include/linux/ceph/osd_client.h
+++ b/include/linux/ceph/osd_client.h
@@ -47,6 +47,7 @@  enum ceph_sparse_read_state {
 	CEPH_SPARSE_READ_DATA_LEN,
 	CEPH_SPARSE_READ_DATA_PRE,
 	CEPH_SPARSE_READ_DATA,
+	CEPH_SPARSE_READ_FINISH,
 };
 
 /*
diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 848ef19055a0..f1705b4f19eb 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -5802,8 +5802,6 @@  static int prep_next_sparse_read(struct ceph_connection *con,
 			advance_cursor(cursor, sr->sr_req_len - end, false);
 	}
 
-	ceph_init_sparse_read(sr);
-
 	/* find next op in this request (if any) */
 	while (++o->o_sparse_op_idx < req->r_num_ops) {
 		op = &req->r_ops[o->o_sparse_op_idx];
@@ -5919,7 +5917,7 @@  static int osd_sparse_read(struct ceph_connection *con,
 				return -EREMOTEIO;
 			}
 
-			sr->sr_state = CEPH_SPARSE_READ_HDR;
+			sr->sr_state = CEPH_SPARSE_READ_FINISH;
 			goto next_op;
 		}
 
@@ -5952,6 +5950,8 @@  static int osd_sparse_read(struct ceph_connection *con,
 		/* Bump the array index */
 		++sr->sr_index;
 		break;
+	case CEPH_SPARSE_READ_FINISH:
+		return 0;
 	}
 	return ret;
 }