[CRIU] [PATCH] page-xfer: repair bug with check_pagehole_in_parent

[Pavel Emelyanov]

On 04/18/2014 01:50 PM, Tikhomirov Pavel wrote:
> 1)it didn't find real pages it had only one step into iterative snapshots
> but what if real page is on the third level?
> 
> patch adds recoursive check in previous images
> 
> 2)it did provide whole intersected pagemap, but it will be more
> convinient to print only intersection part.

Was this all was caught by zdtm? If no, then it's worth creating
a stress test on stackable images. Would you?

> Signed-off-by: Tikhomirov Pavel <snorcht at gmail.com>
> ---
>  page-xfer.c | 18 +++++++++++++++---
>  1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/page-xfer.c b/page-xfer.c
> index 56e8575..0678b54 100644
> --- a/page-xfer.c
> +++ b/page-xfer.c
> @@ -504,7 +504,7 @@ static int check_pagehole_in_parent(struct page_read *p, struct iovec *iov)
>  	off = (unsigned long)iov->iov_base;
>  	end = off + iov->iov_len;
>  	while (1) {
> -		struct iovec piov;
> +		struct iovec piov, tiov;
>  		unsigned long pend;
>  
>  		ret = seek_pagemap_page(p, off, true);
> @@ -512,7 +512,20 @@ static int check_pagehole_in_parent(struct page_read *p, struct iovec *iov)
>  			return -1;
>  
>  		pagemap2iovec(p->pe, &piov);
> -		pr_debug("\tFound %p/%zu\n", piov.iov_base, piov.iov_len);
> +		pend = (unsigned long)piov.iov_base + piov.iov_len;
> +
> +		tiov.iov_base = (void*)off;
> +		tiov.iov_len = min(pend, end) - off;
> +		if (!p->pe->in_parent) {
> +			pr_debug("\tFound %p/%zu\n", tiov.iov_base, tiov.iov_len);
> +		} else {
> +			if (p->parent)
> +				check_pagehole_in_parent(p->parent, &tiov);
> +			else {
> +				pr_err("No parent, though pagemap is in_parent");
> +				return -1;
> +			}
> +		}
>  
>  		/*
>  		 * The pagemap entry in parent may heppen to be
> @@ -520,7 +533,6 @@ static int check_pagehole_in_parent(struct page_read *p, struct iovec *iov)
>  		 * we should go ahead and check the remainder.
>  		 */
>  
> -		pend = (unsigned long)piov.iov_base + piov.iov_len;
>  		if (end <= pend)
>  			return 0;
>  
>