Re: [PATCH v3 5/6] netfs, 9p, afs, ceph: Use folios

Matthew Wilcox
2021-11-03T14:25:38Z

On Tue, Nov 02, 2021 at 08:31:14AM +0000, David Howells wrote:
> -static int v9fs_vfs_writepage_locked(struct page *page)
> +static int v9fs_vfs_write_folio_locked(struct folio *folio)
> {
> - struct inode *inode = page->mapping->host;
> + struct inode *inode = folio_inode(folio);
> struct v9fs_inode *v9inode = V9FS_I(inode);
> - loff_t start = page_offset(page);
> + loff_t start = folio_pos(folio);
> loff_t size = i_size_read(inode);
> struct iov_iter from;
> - int err, len;
> + size_t gran = folio_size(folio), len;
> + int err;
>
> - if (page->index == size >> PAGE_SHIFT)
> - len = size & ~PAGE_MASK;
> - else
> - len = PAGE_SIZE;
> + len = (size >= start + gran) ? gran : size - start;

This seems like the most complicated way to write this ... how about:

size_t len = min_t(loff_t, isize - start, folio_size(folio));

> @@ -322,23 +322,24 @@ static void afs_req_issue_op(struct netfs_read_subrequest *subreq)
>
> static int afs_symlink_readpage(struct file *file, struct page *page)
> {
> - struct afs_vnode *vnode = AFS_FS_I(page->mapping->host);
> + struct afs_vnode *vnode = AFS_FS_I(page_mapping(page)->host);

How does swap end up calling readpage on a symlink?

> ret = afs_fetch_data(fsreq->vnode, fsreq);
> - page_endio(page, false, ret);
> + page_endio(&folio->page, false, ret);

We need a folio_endio() ...

> int afs_write_end(struct file *file, struct address_space *mapping,
> loff_t pos, unsigned len, unsigned copied,
> - struct page *page, void *fsdata)
> + struct page *subpage, void *fsdata)
> {
> + struct folio *folio = page_folio(subpage);
> struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
> unsigned long priv;
> - unsigned int f, from = pos & (thp_size(page) - 1);
> + unsigned int f, from = pos & (folio_size(folio) - 1);

Isn't that:

size_t from = offset_in_folio(folio, pos);

(not that i think we're getting folios larger than 4GB any time soon,
but it'd be nice to be prepared for it)