[CRIU] [PATCH 2/3] page-read: Add async arg to ->read_pages callback

[Mike Rapoport]

On Mon, Nov 07, 2016 at 07:03:07PM +0300, Pavel Emelyanov wrote:
> Flag PR_ASYNC means, that the caller is OK if the routine
> returns w/o data read into the buffer provided.
> 
> Flag PR_UNPLUG means, that the caller nonetheless wants the
> data to be available ASAP.

This one does not seem to be used neither in this patch nor in the next
one.
Can you elaborate on how it should/will be used? From the description
above, the name should be PR_ASAP if we'd ever use it ;-)
 
> Signed-off-by: Pavel Emelyanov <xemul at virtuozzo.com>
> ---
>  criu/include/pagemap.h | 6 +++++-
>  criu/mem.c             | 4 ++--
>  criu/pagemap.c         | 5 +++--
>  criu/shmem.c           | 2 +-
>  criu/uffd.c            | 2 +-
>  5 files changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/criu/include/pagemap.h b/criu/include/pagemap.h
> index 705a9af..b445d82 100644
> --- a/criu/include/pagemap.h
> +++ b/criu/include/pagemap.h
> @@ -47,7 +47,7 @@ struct page_read {
>  	 */
>  	int (*get_pagemap)(struct page_read *, struct iovec *iov);
>  	/* reads page from current pagemap */
> -	int (*read_pages)(struct page_read *, unsigned long vaddr, int nr, void *);
> +	int (*read_pages)(struct page_read *, unsigned long vaddr, int nr, void *, unsigned flags);
>  	void (*close)(struct page_read *);
>  	void (*skip_pages)(struct page_read *, unsigned long len);
>  	int (*seek_page)(struct page_read *pr, unsigned long vaddr, bool warn);
> @@ -74,6 +74,10 @@ struct page_read {
>  	int curr_pme;
>  };
> 
> +/* flags for ->read_pages */
> +#define PR_ASYNC	0x1 /* may exit w/o data in the buffer */
> +#define PR_UNPLUG	0x2 /* do async, but start the IO asap */
> +
>  #define PR_SHMEM	0x1
>  #define PR_TASK		0x2
> 
> diff --git a/criu/mem.c b/criu/mem.c
> index 809b637..7da64f5 100644
> --- a/criu/mem.c
> +++ b/criu/mem.c
> @@ -790,7 +790,7 @@ static int restore_priv_vma_content(struct pstree_item *t)
>  			if (vma->ppage_bitmap) { /* inherited vma */
>  				clear_bit(off, vma->ppage_bitmap);
> 
> -				ret = pr.read_pages(&pr, va, 1, buf);
> +				ret = pr.read_pages(&pr, va, 1, buf, 0);
>  				if (ret < 0)
>  					goto err_read;
> 
> @@ -818,7 +818,7 @@ static int restore_priv_vma_content(struct pstree_item *t)
> 
>  				nr = min_t(int, nr_pages - i, (vma->e->end - va) / PAGE_SIZE);
> 
> -				ret = pr.read_pages(&pr, va, nr, p);
> +				ret = pr.read_pages(&pr, va, nr, p, PR_ASYNC);
>  				if (ret < 0)
>  					goto err_read;
> 
> diff --git a/criu/pagemap.c b/criu/pagemap.c
> index cfc9659..0a072c8 100644
> --- a/criu/pagemap.c
> +++ b/criu/pagemap.c
> @@ -205,7 +205,8 @@ static inline void pagemap_bound_check(PagemapEntry *pe, unsigned long vaddr, in
>  	}
>  }
> 
> -static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, int nr, void *buf)
> +static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, int nr,
> +		void *buf, unsigned flags)
>  {
>  	int ret;
>  	unsigned long len = nr * PAGE_SIZE;
> @@ -242,7 +243,7 @@ static int read_pagemap_page(struct page_read *pr, unsigned long vaddr, int nr,
>  			if (p_nr > nr)
>  				p_nr = nr;
> 
> -			ret = read_pagemap_page(ppr, vaddr, p_nr, buf);
> +			ret = read_pagemap_page(ppr, vaddr, p_nr, buf, flags);
>  			if (ret == -1)
>  				return ret;
> 
> diff --git a/criu/shmem.c b/criu/shmem.c
> index 5065abd..05028a3 100644
> --- a/criu/shmem.c
> +++ b/criu/shmem.c
> @@ -485,7 +485,7 @@ static int restore_shmem_content(void *addr, struct shmem_info *si)
>  		if (vaddr + nr_pages * PAGE_SIZE > si->size)
>  			break;
> 
> -		pr.read_pages(&pr, vaddr, nr_pages, addr + vaddr);
> +		pr.read_pages(&pr, vaddr, nr_pages, addr + vaddr, 0);
>  	}
> 
>  	pr.close(&pr);
> diff --git a/criu/uffd.c b/criu/uffd.c
> index e6d4069..3336651 100644
> --- a/criu/uffd.c
> +++ b/criu/uffd.c
> @@ -398,7 +398,7 @@ static int get_page(struct lazy_pages_info *lpi, unsigned long addr, void *dest)
>  	if (pagemap_zero(lpi->pr.pe))
>  		return 0;
> 
> -	ret = lpi->pr.read_pages(&lpi->pr, addr, 1, buf);
> +	ret = lpi->pr.read_pages(&lpi->pr, addr, 1, buf, 0);
>  	pr_debug("read_pages ret %d\n", ret);
>  	if (ret <= 0)
>  		return ret;
> -- 
> 2.1.4
> 
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