On Tue, Feb 28, 2017 at 11:41:34PM +0800, 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@xxxxxxxxx>
> ---
> drivers/md/md.h | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 54 insertions(+)
>
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 1d63239a1be4..b5a638d85cb4 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -720,4 +720,58 @@ 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];
> +};
I'd like this to be embedded into r1bio directly. Not sure if we really need a
structure.
> +
> +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)
> + __free_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++)
> + __free_page(rp->pages[i]);
Since we will use get_page, shouldn't this be put_page?
> +}
> +
> +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)
> +{
> + if (WARN_ON_ONCE(rp->idx >= RESYNC_PAGES))
> + return NULL;
> + return rp->pages[rp->idx++];
I'd like the caller explicitly specify the index instead of a global variable
to track it, which will make the code more understandable and less error prone.
> +}
> +
> +static inline bool resync_page_available(struct resync_pages *rp)
> +{
> + return rp->idx < RESYNC_PAGES;
> +}
Then we don't need this obscure API.
Thanks,
Shaohua
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