On Wed, Mar 16, 2022 at 09:17:22PM +0800, Jeffle Xu wrote:
> This patch implements fscache-based data readahead. Also registers an
> individual bdi for each erofs instance to enable readahead.
>
> Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
> ---
> fs/erofs/fscache.c | 153 +++++++++++++++++++++++++++++++++++++++++++++
> fs/erofs/super.c | 4 ++
> 2 files changed, 157 insertions(+)
>
> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
> index 82c52b6e077e..913ca891deb9 100644
> --- a/fs/erofs/fscache.c
> +++ b/fs/erofs/fscache.c
> @@ -10,6 +10,13 @@ struct erofs_fscache_map {
> u64 m_llen;
> };
>
> +struct erofs_fscahce_ra_ctx {
typo, should be `erofs_fscache_ra_ctx'
> + struct readahead_control *rac;
> + struct address_space *mapping;
> + loff_t start;
> + size_t len, done;
> +};
> +
> static struct fscache_volume *volume;
>
> /*
> @@ -199,12 +206,158 @@ static int erofs_fscache_readpage(struct file *file, struct page *page)
> return ret;
> }
>
> +static inline size_t erofs_fscache_calc_len(struct erofs_fscahce_ra_ctx *ractx,
> + struct erofs_fscache_map *fsmap)
> +{
> + /*
> + * 1) For CHUNK_BASED layout, the output m_la is rounded down to the
> + * nearest chunk boundary, and the output m_llen actually starts from
> + * the start of the containing chunk.
> + * 2) For other cases, the output m_la is equal to o_la.
> + */
> + size_t len = fsmap->m_llen - (fsmap->o_la - fsmap->m_la);
> +
> + return min_t(size_t, len, ractx->len - ractx->done);
> +}
> +
> +static inline void erofs_fscache_unlock_pages(struct readahead_control *rac,
> + size_t len)
Can we convert them into folios in advance? it seems much
straight-forward to convert these...
Or I have to convert them later, and it seems unnecessary...
> +{
> + while (len) {
> + struct page *page = readahead_page(rac);
> +
> + SetPageUptodate(page);
> + unlock_page(page);
> + put_page(page);
> +
> + len -= PAGE_SIZE;
> + }
> +}
> +
> +static int erofs_fscache_ra_hole(struct erofs_fscahce_ra_ctx *ractx,
> + struct erofs_fscache_map *fsmap)
> +{
> + struct iov_iter iter;
> + loff_t start = ractx->start + ractx->done;
> + size_t length = erofs_fscache_calc_len(ractx, fsmap);
> +
> + iov_iter_xarray(&iter, READ, &ractx->mapping->i_pages, start, length);
> + iov_iter_zero(length, &iter);
> +
> + erofs_fscache_unlock_pages(ractx->rac, length);
> + return length;
> +}
> +
> +static int erofs_fscache_ra_noinline(struct erofs_fscahce_ra_ctx *ractx,
> + struct erofs_fscache_map *fsmap)
> +{
> + struct fscache_cookie *cookie = fsmap->m_ctx->cookie;
> + loff_t start = ractx->start + ractx->done;
> + size_t length = erofs_fscache_calc_len(ractx, fsmap);
> + loff_t pstart = fsmap->m_pa + (fsmap->o_la - fsmap->m_la);
> + int ret;
> +
> + ret = erofs_fscache_read_pages(cookie, ractx->mapping,
> + start, length, pstart);
> + if (!ret) {
> + erofs_fscache_unlock_pages(ractx->rac, length);
> + ret = length;
> + }
> +
> + return ret;
> +}
> +
> +static int erofs_fscache_ra_inline(struct erofs_fscahce_ra_ctx *ractx,
> + struct erofs_fscache_map *fsmap)
> +{
We could fold in this, since it has the only user.
Thanks,
Gao Xiang
