[CRIU] [PATCH 12/12] page-xfer: Sanitize xfer core routine

[Mike Rapoport]

On Wed, Jun 28, 2017 at 04:48:45PM +0300, Pavel Emelyanov wrote:
> Make it call .write_pagemap once and decide whether or not to
> call .write_pages based on the flags caluculated in one place
> as well.
> 
> Signed-off-by: Pavel Emelyanov <xemul at virtuozzo.com>
> ---
>  criu/page-xfer.c | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)
> 
> diff --git a/criu/page-xfer.c b/criu/page-xfer.c
> index 10da75f..256cac6 100644
> --- a/criu/page-xfer.c
> +++ b/criu/page-xfer.c
> @@ -405,6 +405,14 @@ static int dump_holes(struct page_xfer *xfer, struct page_pipe *pp,
>  	return 0;
>  }
> 
> +static inline u32 ppb_xfer_flags(struct page_xfer *xfer, struct page_pipe_buf *ppb)
> +{
> +	if (ppb->flags & PPB_LAZY)
> +		return PE_LAZY | (xfer->transfer_lazy ? PE_PRESENT : 0);

Huh. Then maybe even

return ppb->flags & PPB_LAZY ? PE_LAZY | (xfer->transfer_lazy ? PE_PRESENT : 0) : PE_PRESENT;

;-)


I understand that if's and braces are not Spartan enough, but can we at
least switch the order:

	return (xfer->transfer_lazy ? PE_PRESENT : 0) | PE_LAZY;

and add a comment, e.g.:

	/*
	 * Pages that can be lazily restored are always marked as such. In
	 * the case we actually transfer them into image make them as
	 * present as well.
	 */

> +	else
> +		return PE_PRESENT;
> +}
> +
>  int page_xfer_dump_pages(struct page_xfer *xfer, struct page_pipe *pp)
>  {
>  	struct page_pipe_buf *ppb;
> @@ -420,7 +428,7 @@ int page_xfer_dump_pages(struct page_xfer *xfer, struct page_pipe *pp)
> 
>  		for (i = 0; i < ppb->nr_segs; i++) {
>  			struct iovec iov = ppb->iov[i];
> -			u32 flags = PE_PRESENT;
> +			u32 flags;
> 
>  			ret = dump_holes(xfer, pp, &cur_hole, iov.iov_base);
>  			if (ret)
> @@ -431,19 +439,12 @@ int page_xfer_dump_pages(struct page_xfer *xfer, struct page_pipe *pp)
>  			pr_debug("\tp %p [%u]\n", iov.iov_base,
>  					(unsigned int)(iov.iov_len / PAGE_SIZE));
> 
> -			if (ppb->flags & PPB_LAZY) {
> -				if (!xfer->transfer_lazy) {
> -					if (xfer->write_pagemap(xfer, &iov, PE_LAZY))
> -						return -1;
> -					continue;
> -				} else {
> -					flags |= PE_LAZY;
> -				}
> -			}
> +			flags = ppb_xfer_flags(xfer, ppb);
> 
>  			if (xfer->write_pagemap(xfer, &iov, flags))
>  				return -1;
> -			if (xfer->write_pages(xfer, ppb->p[0], iov.iov_len))
> +			if ((flags & PE_PRESENT) && xfer->write_pages(xfer,
> +						ppb->p[0], iov.iov_len))

Huh again. A newline after && ?

>  				return -1;
>  		}
>  	}
> -- 
> 2.1.4
> 
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