Re: [PATCH v6 11/16] erofs: Convert compressed files from readpages to readahead

Gao Xiang
2020-02-19T02:35:47Z

On Mon, Feb 17, 2020 at 10:46:00AM -0800, Matthew Wilcox wrote:
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
>
> Use the new readahead operation in erofs.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

It looks good to me, although some further optimization exists
but we could make a straight-forward transform first, and
I haven't tested the whole series for now...
Will test it later.

Acked-by: Gao Xiang <gaoxiang25@huawei.com>

Thanks,
Gao Xiang

> ---
> fs/erofs/zdata.c | 29 +++++++++--------------------
> 1 file changed, 9 insertions(+), 20 deletions(-)
>
> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> index 17f45fcb8c5c..7c02015d501d 100644
> --- a/fs/erofs/zdata.c
> +++ b/fs/erofs/zdata.c
> @@ -1303,28 +1303,23 @@ static bool should_decompress_synchronously(struct erofs_sb_info *sbi,
> return nr <= sbi->max_sync_decompress_pages;
> }
>
> -static int z_erofs_readpages(struct file *filp, struct address_space *mapping,
> - struct list_head *pages, unsigned int nr_pages)
> +static void z_erofs_readahead(struct readahead_control *rac)
> {
> - struct inode *const inode = mapping->host;
> + struct inode *const inode = rac->mapping->host;
> struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
>
> - bool sync = should_decompress_synchronously(sbi, nr_pages);
> + bool sync = should_decompress_synchronously(sbi, readahead_count(rac));
> struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
> - gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL);
> - struct page *head = NULL;
> + struct page *page, *head = NULL;
> LIST_HEAD(pagepool);
>
> - trace_erofs_readpages(mapping->host, lru_to_page(pages)->index,
> - nr_pages, false);
> + trace_erofs_readpages(inode, readahead_index(rac),
> + readahead_count(rac), false);
>
> - f.headoffset = (erofs_off_t)lru_to_page(pages)->index << PAGE_SHIFT;
> -
> - for (; nr_pages; --nr_pages) {
> - struct page *page = lru_to_page(pages);
> + f.headoffset = readahead_offset(rac);
>
> + readahead_for_each(rac, page) {
> prefetchw(&page->flags);
> - list_del(&page->lru);
>
> /*
> * A pure asynchronous readahead is indicated if
> @@ -1333,11 +1328,6 @@ static int z_erofs_readpages(struct file *filp, struct address_space *mapping,
> */
> sync &= !(PageReadahead(page) && !head);
>
> - if (add_to_page_cache_lru(page, mapping, page->index, gfp)) {
> - list_add(&page->lru, &pagepool);
> - continue;
> - }
> -
> set_page_private(page, (unsigned long)head);
> head = page;
> }
> @@ -1366,11 +1356,10 @@ static int z_erofs_readpages(struct file *filp, struct address_space *mapping,
>
> /* clean up the remaining free pages */
> put_pages_list(&pagepool);
> - return 0;
> }
>
> const struct address_space_operations z_erofs_aops = {
> .readpage = z_erofs_readpage,
> - .readpages = z_erofs_readpages,
> + .readahead = z_erofs_readahead,
> };
>
> --
> 2.25.0
>
>