linux-kernel - [PATCH 3.10 077/268] nfs_write_end(): fix handling of short copies

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Message-Id: <1497897167-14556-78-git-send-email-w@1wt.eu>
Date:   Mon, 19 Jun 2017 20:29:36 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Al Viro <viro@...iv.linux.org.uk>, Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 077/268] nfs_write_end(): fix handling of short copies

From: Al Viro <viro@...iv.linux.org.uk>

commit c0cf3ef5e0f47e385920450b245d22bead93e7ad upstream.

What matters when deciding if we should make a page uptodate is
not how much we _wanted_ to copy, but how much we actually have
copied.  As it is, on architectures that do not zero tail on
short copy we can leave uninitialized data in page marked uptodate.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Willy Tarreau <w@....eu>
---
 fs/nfs/file.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index a87a44f..f8bd4ea 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -419,7 +419,7 @@ static int nfs_write_end(struct file *file, struct address_space *mapping,
 	 */
 	if (!PageUptodate(page)) {
 		unsigned pglen = nfs_page_length(page);
-		unsigned end = offset + len;
+		unsigned end = offset + copied;
 
 		if (pglen == 0) {
 			zero_user_segments(page, 0, offset,
-- 
2.8.0.rc2.1.gbe9624a