[PATCH v8 19/25] erofs: Convert compressed files from readpages to readahead

Matthew Wilcox
2020-02-25T21:50:21Z

Use the new readahead operation in erofs.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
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..e64d8ab0900d 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_pos(rac);

+ while ((page = readahead_page(rac))) {
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