From: Kazuo Ito <ito_kazuo_g3@lab.ntt.co.jp>
Date: Thu, 14 Feb 2019 09:36:58 +0000 (+0900)
Subject: pNFS: Fix potential corruption of page being written
X-Git-Tag: v5.1-rc1~48^2~48
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=97ae91bbf3a70fc8cee3c9030564cfc892cc8cee;p=linux.git

pNFS: Fix potential corruption of page being written

nfs_want_read_modify_write() didn't check for !PagePrivate when pNFS
block or SCSI layout was in use, therefore we could lose data forever
if the page being written was filled by a read before completion.

Signed-off-by: Kazuo Ito <ito_kazuo_g3@lab.ntt.co.jp>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index e4a33e66f417..7086d5677ed3 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -299,7 +299,7 @@ static int nfs_want_read_modify_write(struct file *file, struct page *page,
 	unsigned int end = offset + len;
 
 	if (pnfs_ld_read_whole_page(file->f_mapping->host)) {
-		if (!PageUptodate(page))
+		if (!PageUptodate(page) && !PagePrivate(page))
 			return 1;
 		return 0;
 	}