linux-kernel - [PATCH v5 16/18] mm/filemap: Don't relock the page after calling readpage

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Date:   Fri, 22 Jan 2021 16:01:38 +0000
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Kent Overstreet <kent.overstreet@...il.com>,
        Christoph Hellwig <hch@....de>
Subject: [PATCH v5 16/18] mm/filemap: Don't relock the page after calling readpage

We don't need to get the page lock again; we just need to wait for
the I/O to finish, so use wait_on_page_locked_killable() like the
other callers of ->readpage.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Reviewed-by: Kent Overstreet <kent.overstreet@...il.com>
Reviewed-by: Christoph Hellwig <hch@....de>
---
 mm/filemap.c | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 1fba96dab4b8e..542d9c93732c2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2227,23 +2227,16 @@ static int filemap_read_page(struct file *file, struct address_space *mapping,
 	error = mapping->a_ops->readpage(file, page);
 	if (error)
 		return error;
-	if (PageUptodate(page))
-		return 0;
 
-	error = lock_page_killable(page);
+	error = wait_on_page_locked_killable(page);
 	if (error)
 		return error;
-	if (!PageUptodate(page)) {
-		if (page->mapping == NULL) {
-			/* page truncated */
-			error = AOP_TRUNCATED_PAGE;
-		} else {
-			shrink_readahead_size_eio(&file->f_ra);
-			error = -EIO;
-		}
-	}
-	unlock_page(page);
-	return error;
+	if (PageUptodate(page))
+		return 0;
+	if (!page->mapping)	/* page truncated */
+		return AOP_TRUNCATED_PAGE;
+	shrink_readahead_size_eio(&file->f_ra);
+	return -EIO;
 }
 
 static bool filemap_range_uptodate(struct address_space *mapping,
-- 
2.29.2