[CRIU] [PATCH v5 4/8] criu: page-{pipe, xfer}: add helper function for dumping holes

[Pavel Emelyanov]

On 06/29/2016 08:55 AM, Mike Rapoport wrote:
> Signed-off-by: Mike Rapoport <rppt at linux.vnet.ibm.com>
> ---
>  criu/include/page-pipe.h |  1 +
>  criu/page-pipe.c         |  2 ++
>  criu/page-xfer.c         | 54 +++++++++++++++++++++++-------------------------
>  3 files changed, 29 insertions(+), 28 deletions(-)
> 
> diff --git a/criu/include/page-pipe.h b/criu/include/page-pipe.h
> index a018af0..f11071c 100644
> --- a/criu/include/page-pipe.h
> +++ b/criu/include/page-pipe.h
> @@ -83,6 +83,7 @@ struct page_pipe_buf {
>  struct page_pipe_iovs {
>  	unsigned int nr_iovs;	/* number of iovs */
>  	unsigned int free_iov;	/* number of iovs in use */
> +	unsigned int busy_iov;	/* first iov that not yet dumped */

Can we avoid having a member on page_pipe_iovs that is used in one
callstack only? And have a variable on the stack itself?

>  	struct iovec *iovs;	/* iovs */
>  };
>  
> diff --git a/criu/page-pipe.c b/criu/page-pipe.c
> index 9bc7eaf..d002c3a 100644
> --- a/criu/page-pipe.c
> +++ b/criu/page-pipe.c
> @@ -149,10 +149,12 @@ struct page_pipe *create_page_pipe(unsigned int nr_segs,
>  	pp->pages.nr_iovs = nr_segs;
>  	pp->pages.iovs = iovs;
>  	pp->pages.free_iov = 0;
> +	pp->pages.busy_iov = 0;
>  
>  	pp->holes.nr_iovs = 0;
>  	pp->holes.free_iov = 0;
>  	pp->holes.iovs = NULL;
> +	pp->holes.busy_iov = 0;
>  
>  	pp->chunk_mode = chunk_mode;
>  
> diff --git a/criu/page-xfer.c b/criu/page-xfer.c
> index 4bb8ea0..32b50f7 100644
> --- a/criu/page-xfer.c
> +++ b/criu/page-xfer.c
> @@ -320,17 +320,35 @@ int open_page_xfer(struct page_xfer *xfer, int fd_type, long id)
>  		return open_page_local_xfer(xfer, fd_type, id);
>  }
>  
> +static int dump_hole(struct page_xfer *xfer, struct page_pipe_iovs *iov,
> +		     void *limit, unsigned long off)
> +{
> +	while (iov->busy_iov < iov->free_iov) {
> +		struct iovec *hole = &iov->iovs[iov->busy_iov];
> +
> +		if (limit && hole->iov_base >= limit)
> +			break;
> +
> +		BUG_ON(hole->iov_base < (void *)off);
> +		hole->iov_base -= off;
> +		pr_debug("\th %p [%u]\n", hole->iov_base,
> +			 (unsigned int)(hole->iov_len / PAGE_SIZE));
> +		if (xfer->write_hole(xfer, hole))
> +			return -1;
> +
> +		iov->busy_iov++;
> +	}
> +
> +	return 0;
> +}
> +
>  int page_xfer_dump_pages(struct page_xfer *xfer, struct page_pipe *pp,
>  		unsigned long off)
>  {
>  	struct page_pipe_buf *ppb;
> -	struct iovec *hole = NULL;
>  
>  	pr_debug("Transfering pages:\n");
>  
> -	if (pp->holes.free_iov)
> -		hole = &pp->holes.iovs[0];
> -
>  	list_for_each_entry(ppb, &pp->bufs, l) {
>  		int i;
>  
> @@ -339,18 +357,8 @@ 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];
>  
> -			while (hole && (hole->iov_base < iov->iov_base)) {
> -				BUG_ON(hole->iov_base < (void *)off);
> -				hole->iov_base -= off;
> -				pr_debug("\th %p [%u]\n", hole->iov_base,
> -						(unsigned int)(hole->iov_len / PAGE_SIZE));
> -				if (xfer->write_hole(xfer, hole))
> -					return -1;
> -
> -				hole++;
> -				if (hole >= &pp->holes.iovs[pp->holes.free_iov])
> -					hole = NULL;
> -			}
> +			if (dump_hole(xfer, &pp->holes, iov->iov_base, off))
> +				return -1;
>  
>  			BUG_ON(iov->iov_base < (void *)off);
>  			iov->iov_base -= off;
> @@ -364,18 +372,8 @@ int page_xfer_dump_pages(struct page_xfer *xfer, struct page_pipe *pp,
>  		}
>  	}
>  
> -	while (hole) {
> -		BUG_ON(hole->iov_base < (void *)off);
> -		hole->iov_base -= off;
> -		pr_debug("\th* %p [%u]\n", hole->iov_base,
> -				(unsigned int)(hole->iov_len / PAGE_SIZE));
> -		if (xfer->write_hole(xfer, hole))
> -			return -1;
> -
> -		hole++;
> -		if (hole >= &pp->holes.iovs[pp->holes.free_iov])
> -			hole = NULL;
> -	}
> +	if (dump_hole(xfer, &pp->holes, NULL, off))
> +		return -1;
>  
>  	return 0;
>  }
>