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From:   Matthew Wilcox <willy@infradead.org>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
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        ocfs2-devel@oss.oracle.com, linux-xfs@vger.kernel.org,
        Gao Xiang <gaoxiang25@huawei.com>,
        Dave Chinner <dchinner@redhat.com>,
        William Kucharski <william.kucharski@oracle.com>,
        Chao Yu <yuchao0@huawei.com>
Subject: [PATCH v11 19/25] erofs: Convert compressed files from readpages to readahead
Date:   Tue, 14 Apr 2020 08:02:27 -0700
Message-Id: <20200414150233.24495-20-willy@infradead.org>
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From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

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>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Chao Yu <yuchao0@huawei.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 a78108128af3..187f93b4900e 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1305,28 +1305,23 @@ 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
@@ -1335,11 +1330,6 @@ 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;
 	}
@@ -1368,11 +1358,10 @@ 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,
 };
 
-- 
2.25.1