On Wed, Apr 06, 2022 at 03:56:10PM +0800, Jeffle Xu wrote:
> Implement the data plane of reading data from data blobs over fscache
> for inline layout.
>
> For the heading non-inline part, the data plane for non-inline layout is
> reused, while only the tail packing part needs special handling.
>
> Signed-off-by: Jeffle Xu <jeffl...@linux.alibaba.com>
> ---
> fs/erofs/fscache.c | 40 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 40 insertions(+)
>
> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
> index 65de1c754e80..d32cb5840c6d 100644
> --- a/fs/erofs/fscache.c
> +++ b/fs/erofs/fscache.c
> @@ -60,6 +60,40 @@ static int erofs_fscache_meta_readpage(struct file *data,
> struct page *page)
> return ret;
> }
>
> +static int erofs_fscache_readpage_inline(struct folio *folio,
> + struct erofs_map_blocks *map)
> +{
> + struct inode *inode = folio_file_mapping(folio)->host;
> + struct super_block *sb = inode->i_sb;
> + struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
> + erofs_blk_t blknr;
> + size_t offset, len;
> + void *src, *dst;
> +
> + /*
> + * For inline (tail packing) layout, the offset may be non-zero, which
> + * can be calculated from corresponding physical address directly.
> + */
> + offset = erofs_blkoff(map->m_pa);
> + blknr = erofs_blknr(map->m_pa);
> + len = map->m_llen;
> +
> + src = erofs_read_metabuf(&buf, sb, blknr, EROFS_KMAP);
> + if (IS_ERR(src))
> + return PTR_ERR(src);
> +
> + DBG_BUGON(folio_size(folio) != PAGE_SIZE);
> +
> + dst = kmap(folio_page(folio, 0));
kmap_local_folio?
> + memcpy(dst, src + offset, len);
> + memset(dst + len, 0, PAGE_SIZE - len);
> + kunmap(folio_page(folio, 0));
> +
> + erofs_put_metabuf(&buf);
> +
> + return 0;
> +}
> +
> static int erofs_fscache_readpage(struct file *file, struct page *page)
> {
> struct folio *folio = page_folio(page);
> @@ -85,6 +119,12 @@ static int erofs_fscache_readpage(struct file *file,
> struct page *page)
> goto out_uptodate;
> }
>
> + /* inline readpage */
I think the code below is self-explained.
> + if (map.m_flags & EROFS_MAP_META) {
> + ret = erofs_fscache_readpage_inline(folio, &map);
> + goto out_uptodate;
> + }
> +
> /* no-inline readpage */
Same here.
Thanks,
Gao Xiang
> mdev = (struct erofs_map_dev) {
> .m_deviceid = map.m_deviceid,
> --
> 2.27.0
>
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