From:   Kazuo Ito <ito_kazuo_g3@lab.ntt.co.jp>
Subject: [PATCH v2 1/2] pNFS: Fix potential corruption of page being written
Message-ID: <480b4d46-e290-b612-7b8e-09eb3a488ee6@lab.ntt.co.jp>
Date:   Thu, 14 Feb 2019 18:36:58 +0900
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To:     trond.myklebust@hammerspace.com, anna.schumaker@netapp.com
Cc:     linux-nfs@vger.kernel.org, konishi.ryusuke@lab.ntt.co.jp,
        =?UTF-8?B?T1PmuKHovro=?= <watanabe.hiroyuki@lab.ntt.co.jp>
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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>
---
 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 29553fdba8af..d8f25b1ae233 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;
 	}
-- 
2.20.1