Re: [PATCH v3 03/14] md: prepare for managing resync I/O pages in clean way

[NeilBrown <neilb@suse.com>]

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On Fri, Mar 17 2017, Ming Lei wrote:

> Now resync I/O use bio's bec table to manage pages,
> this way is very hacky, and may not work any more
> once multipage bvec is introduced.
>
> So introduce helpers and new data structure for
> managing resync I/O pages more cleanly.
>
> Signed-off-by: Ming Lei <tom.leiming@gmail.com>
> ---
>  drivers/md/md.h | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 50 insertions(+)

I don't think this should go in md.h

Maybe create a "raid1-10.h" or similar if you really want to.

NeilBrown

>
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 1d63239a1be4..20c48032493b 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -720,4 +720,54 @@ static inline void mddev_check_writesame(struct mddev *mddev, struct bio *bio)
>  #define RESYNC_BLOCK_SIZE (64*1024)
>  #define RESYNC_PAGES ((RESYNC_BLOCK_SIZE + PAGE_SIZE-1) / PAGE_SIZE)
>  
> +/* for managing resync I/O pages */
> +struct resync_pages {
> +	unsigned	idx;	/* for get/put page from the pool */
> +	void		*raid_bio;
> +	struct page	*pages[RESYNC_PAGES];
> +};
> +
> +static inline int resync_alloc_pages(struct resync_pages *rp,
> +				     gfp_t gfp_flags)
> +{
> +	int i;
> +
> +	for (i = 0; i < RESYNC_PAGES; i++) {
> +		rp->pages[i] = alloc_page(gfp_flags);
> +		if (!rp->pages[i])
> +			goto out_free;
> +	}
> +
> +	return 0;
> +
> + out_free:
> +	while (--i >= 0)
> +		put_page(rp->pages[i]);
> +	return -ENOMEM;
> +}
> +
> +static inline void resync_free_pages(struct resync_pages *rp)
> +{
> +	int i;
> +
> +	for (i = 0; i < RESYNC_PAGES; i++)
> +		put_page(rp->pages[i]);
> +}
> +
> +static inline void resync_get_all_pages(struct resync_pages *rp)
> +{
> +	int i;
> +
> +	for (i = 0; i < RESYNC_PAGES; i++)
> +		get_page(rp->pages[i]);
> +}
> +
> +static inline struct page *resync_fetch_page(struct resync_pages *rp,
> +					     unsigned idx)
> +{
> +	if (WARN_ON_ONCE(idx >= RESYNC_PAGES))
> +		return NULL;
> +	return rp->pages[idx];
> +}
> +
>  #endif /* _MD_MD_H */
> -- 
> 2.9.3
>
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