[CRIU] [PATCH] page-xfer: Fixup page server protocol for lazy pages

[Pavel Emelyanov]

On 06/21/2017 09:27 PM, Mike Rapoport wrote:
> On Wed, Jun 21, 2017 at 5:10 PM, Pavel Emelyanov <xemul at virtuozzo.com> wrote:
>> Introduce the PS_IOV_ADD_F command that is to add pages with
>> flags. We already use the similar notation on page-xfer -- the
>> single write callback with pagemap and flags. For page-server
>> let's use the same. Legacy _HOLE and _PAGE handling is kept.
>>
>> Changed commands numbers are OK, as the commands in question
>> are still in criu-dev branch.
>>
>> Signed-off-by: Pavel Emelyanov <xemul at virtuozzo.com>
>> ---
>>  criu/page-xfer.c | 49 +++++++++++++++++++++++++------------------------
>>  1 file changed, 25 insertions(+), 24 deletions(-)
>>
>> diff --git a/criu/page-xfer.c b/criu/page-xfer.c
>> index 49693bb..125001a 100644
>> --- a/criu/page-xfer.c
>> +++ b/criu/page-xfer.c
>> @@ -42,9 +42,8 @@ static void psi2iovec(struct page_server_iov *ps, struct iovec *iov)
>>  #define PS_IOV_OPEN    3
>>  #define PS_IOV_OPEN2   4
>>  #define PS_IOV_PARENT  5
>> -#define PS_IOV_ZERO    6
>> -#define PS_IOV_LAZY    7
>> -#define PS_IOV_GET     8
>> +#define PS_IOV_ADD_F   6
>> +#define PS_IOV_GET     7
>>
>>  #define PS_IOV_FLUSH           0x1023
>>  #define PS_IOV_FLUSH_N_CLOSE   0x1024
>> @@ -118,18 +117,7 @@ static int write_pages_to_server(struct page_xfer *xfer,
>>
>>  static int write_pagemap_to_server(struct page_xfer *xfer, struct iovec *iov, u32 flags)
>>  {
>> -       u32 cmd = 0;
>> -
>> -       if (flags & PE_PRESENT)
>> -               cmd = encode_ps_cmd(PS_IOV_ADD, flags);
>> -       else if (flags & PE_PARENT)
>> -               cmd = PS_IOV_HOLE;
>> -       else if (flags & PE_LAZY)
>> -               cmd = PS_IOV_LAZY;
>> -       else
>> -               BUG();
>> -
>> -       return send_psi(xfer->sk, cmd,
>> +       return send_psi(xfer->sk, encode_ps_cmd(PS_IOV_ADD_F, flags),
>>                         iov->iov_len / PAGE_SIZE, encode_pointer(iov->iov_base),
>>                         xfer->dst_id);
>>  }
>> @@ -680,12 +668,13 @@ static int page_server_get_pages(int sk, struct page_server_iov *pi)
>>         if (pi->nr_pages == 0) {
>>                 /* no iovs found means we've hit a zero page */
>>                 pr_debug("no iovs found, zero pages\n");
>> -               return send_psi(sk, PS_IOV_ZERO, 0, 0, 0);
>> +               return send_psi(sk, encode_ps_cmd(PS_IOV_ADD_F, 0), 0, 0, 0);
>>         }
>>
>>         len = pi->nr_pages * PAGE_SIZE;
>>
>> -       if (send_psi(sk, PS_IOV_ADD, pi->nr_pages, pi->vaddr, pi->dst_id))
>> +       if (send_psi(sk, encode_ps_cmd(PS_IOV_ADD_F, PE_PRESENT),
>> +                               pi->nr_pages, pi->vaddr, pi->dst_id))
>>                 return -1;
>>
>>         ret = splice(pipe_read_dest.p[0], NULL, sk, NULL, len, SPLICE_F_MOVE);
>> @@ -751,15 +740,22 @@ static int page_server_serve(int sk)
>>                 case PS_IOV_PARENT:
>>                         ret = page_server_check_parent(sk, &pi);
>>                         break;
>> +               case PS_IOV_ADD_F:
>>                 case PS_IOV_ADD:
>> -                       ret = page_server_add(sk, &pi, PE_PRESENT | decode_ps_flags(pi.cmd));
>> -                       break;
>>                 case PS_IOV_HOLE:
>> -                       ret = page_server_add(sk, &pi, PE_PARENT);
>> -                       break;
>> -               case PS_IOV_LAZY:
>> -                       ret = page_server_add(sk, &pi, PE_LAZY);
>> +               {
>> +                       u32 flags;
>> +
>> +                       if (likely(cmd == PS_IOV_ADD_F))
>> +                               flags = decode_ps_flags(pi.cmd);
>> +                       else if (cmd == PS_IOV_ADD)
>> +                               flags = PE_PRESENT;
>> +                       else    /* PS_IOV_HOLE */
>> +                               flags = PE_PARENT;
> 
> Maybe a helper function here ?

Yup, why not :) I'll send v2