[PATCH v4 08/12] erofs: Convert compressed files from readpages to readahead

[Matthew Wilcox]

From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>

Use the new readahead operation in erofs.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: linux-erofs@xxxxxxxxxxxxxxxx
---
 fs/erofs/zdata.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 17f45fcb8c5c..97c05200a784 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1303,28 +1303,26 @@ 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
+unsigned z_erofs_readahead(struct file *file, struct address_space *mapping,
+			     pgoff_t start, unsigned int nr_pages)
 {
 	struct inode *const inode = mapping->host;
 	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 
 	bool sync = should_decompress_synchronously(sbi, nr_pages);
 	struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
-	gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL);
 	struct page *head = NULL;
 	LIST_HEAD(pagepool);
 
-	trace_erofs_readpages(mapping->host, lru_to_page(pages)->index,
-			      nr_pages, false);
+	trace_erofs_readpages(inode, start, nr_pages, false);
 
-	f.headoffset = (erofs_off_t)lru_to_page(pages)->index << PAGE_SHIFT;
+	f.headoffset = (erofs_off_t)start << PAGE_SHIFT;
 
 	for (; nr_pages; --nr_pages) {
-		struct page *page = lru_to_page(pages);
+		struct page *page = readahead_page(mapping, start);
 
 		prefetchw(&page->flags);
-		list_del(&page->lru);
 
 		/*
 		 * A pure asynchronous readahead is indicated if
@@ -1333,11 +1331,6 @@ 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;
 	}
@@ -1371,6 +1364,6 @@ static int z_erofs_readpages(struct file *filp, struct address_space *mapping,
 
 const struct address_space_operations z_erofs_aops = {
 	.readpage = z_erofs_readpage,
-	.readpages = z_erofs_readpages,
+	.readahead = z_erofs_readahead,
 };
 
-- 
2.24.1