linux-kernel - [PATCH 4.14 39/78] cifs/smb3: Fix data inconsistent when zero file range

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Date:   Mon, 29 Jun 2020 11:37:27 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Zhang Xiaoxu <zhangxiaoxu5@...wei.com>,
        Hulk Robot <hulkci@...wei.com>,
        Pavel Shilovsky <pshilov@...rosoft.com>,
        Steve French <stfrench@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 39/78] cifs/smb3: Fix data inconsistent when zero file range

From: Zhang Xiaoxu <zhangxiaoxu5@...wei.com>

[ Upstream commit 6b69040247e14b43419a520f841f2b3052833df9 ]

CIFS implements the fallocate(FALLOC_FL_ZERO_RANGE) with send SMB
ioctl(FSCTL_SET_ZERO_DATA) to server. It just set the range of the
remote file to zero, but local page cache not update, then the data
inconsistent with server, which leads the xfstest generic/008 failed.

So we need to remove the local page caches before send SMB
ioctl(FSCTL_SET_ZERO_DATA) to server. After next read, it will
re-cache it.

Fixes: 30175628bf7f5 ("[SMB3] Enable fallocate -z support for SMB3 mounts")
Reported-by: Hulk Robot <hulkci@...wei.com>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@...wei.com>
Reviewed-by: Pavel Shilovsky <pshilov@...rosoft.com>
Cc: stable@...r.kernel.org # v3.17
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/cifs/smb2ops.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 61ea429e1210b..b46fdb2b8d349 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -1755,6 +1755,12 @@ static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon,
 	inode = d_inode(cfile->dentry);
 	cifsi = CIFS_I(inode);
 
+	/*
+	 * We zero the range through ioctl, so we need remove the page caches
+	 * first, otherwise the data may be inconsistent with the server.
+	 */
+	truncate_pagecache_range(inode, offset, offset + len - 1);
+
 	/* if file not oplocked can't be sure whether asking to extend size */
 	if (!CIFS_CACHE_READ(cifsi))
 		if (keep_size == false) {
-- 
2.25.1