On Mon, Apr 25, 2022 at 08:21:39PM +0800, Jeffle Xu wrote:
> Implement the data plane of reading metadata from primary data blob
> over fscache.
>
> Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
Reviewed-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx>
Thanks,
Gao Xiang
> ---
> fs/erofs/data.c | 19 +++++++++++++++----
> fs/erofs/fscache.c | 25 +++++++++++++++++++++++++
> 2 files changed, 40 insertions(+), 4 deletions(-)
>
> diff --git a/fs/erofs/data.c b/fs/erofs/data.c
> index 14b64d960541..bb9c1fd48c19 100644
> --- a/fs/erofs/data.c
> +++ b/fs/erofs/data.c
> @@ -6,6 +6,7 @@
> */
> #include "internal.h"
> #include <linux/prefetch.h>
> +#include <linux/sched/mm.h>
> #include <linux/dax.h>
> #include <trace/events/erofs.h>
>
> @@ -35,14 +36,20 @@ void *erofs_bread(struct erofs_buf *buf, struct inode *inode,
> erofs_off_t offset = blknr_to_addr(blkaddr);
> pgoff_t index = offset >> PAGE_SHIFT;
> struct page *page = buf->page;
> + struct folio *folio;
> + unsigned int nofs_flag;
>
> if (!page || page->index != index) {
> erofs_put_metabuf(buf);
> - page = read_cache_page_gfp(mapping, index,
> - mapping_gfp_constraint(mapping, ~__GFP_FS));
> - if (IS_ERR(page))
> - return page;
> +
> + nofs_flag = memalloc_nofs_save();
> + folio = read_cache_folio(mapping, index, NULL, NULL);
> + memalloc_nofs_restore(nofs_flag);
> + if (IS_ERR(folio))
> + return folio;
> +
> /* should already be PageUptodate, no need to lock page */
> + page = folio_file_page(folio, index);
> buf->page = page;
> }
> if (buf->kmap_type == EROFS_NO_KMAP) {
> @@ -63,6 +70,10 @@ void *erofs_bread(struct erofs_buf *buf, struct inode *inode,
> void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
> erofs_blk_t blkaddr, enum erofs_kmap_type type)
> {
> + if (erofs_is_fscache_mode(sb))
> + return erofs_bread(buf, EROFS_SB(sb)->s_fscache->inode,
> + blkaddr, type);
> +
> return erofs_bread(buf, sb->s_bdev->bd_inode, blkaddr, type);
> }
>
> diff --git a/fs/erofs/fscache.c b/fs/erofs/fscache.c
> index ac02af8cce3e..23d7e862eed8 100644
> --- a/fs/erofs/fscache.c
> +++ b/fs/erofs/fscache.c
> @@ -59,7 +59,32 @@ static int erofs_fscache_read_folios(struct fscache_cookie *cookie,
> return ret;
> }
>
> +static int erofs_fscache_meta_readpage(struct file *data, struct page *page)
> +{
> + int ret;
> + struct folio *folio = page_folio(page);
> + struct super_block *sb = folio_mapping(folio)->host->i_sb;
> + struct erofs_map_dev mdev = {
> + .m_deviceid = 0,
> + .m_pa = folio_pos(folio),
> + };
> +
> + ret = erofs_map_dev(sb, &mdev);
> + if (ret)
> + goto out;
> +
> + ret = erofs_fscache_read_folios(mdev.m_fscache->cookie,
> + folio_mapping(folio), folio_pos(folio),
> + folio_size(folio), mdev.m_pa);
> + if (!ret)
> + folio_mark_uptodate(folio);
> +out:
> + folio_unlock(folio);
> + return ret;
> +}
> +
> static const struct address_space_operations erofs_fscache_meta_aops = {
> + .readpage = erofs_fscache_meta_readpage,
> };
>
> int erofs_fscache_register_cookie(struct super_block *sb,
> --
> 2.27.0
