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

[Andrei Vagin]

This patch conflicts with 483a27809d127c915cf39d450e0880c004e028b4

On Wed, Jun 21, 2017 at 05:10:39PM +0300, Pavel Emelyanov 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;
> +
> +			ret = page_server_add(sk, &pi, flags);
>  			break;
> +		}
>  		case PS_IOV_FLUSH:
>  		case PS_IOV_FLUSH_N_CLOSE:
>  		{
> @@ -1162,7 +1158,12 @@ int receive_remote_pages_info(int *nr_pages, unsigned long *addr, int *pid)
>  		return -1;
>  	}
>  
> -	if (pi.cmd == PS_IOV_ZERO)
> +	if (decode_ps_cmd(pi.cmd) != PS_IOV_ADD_F) {
> +		pr_err("Proto error\n");
> +		return -1;
> +	}
> +
> +	if (!(decode_ps_flags(pi.cmd) & PE_PRESENT))
>  		pr_warn("Unexpected ZERO page received for %d.%lx\n",
>  				(int)pi.dst_id, (unsigned long)pi.vaddr);
>  
> -- 
> 2.1.4
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