[PATCH 4.4 110/135] cifs/smb3: Fix data inconsistent when zero file range

[Sasha Levin]

From: Zhang Xiaoxu <zhangxiaoxu5@xxxxxxxxxx>

[ 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@xxxxxxxxxx>
Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@xxxxxxxxxx>
Reviewed-by: Pavel Shilovsky <pshilov@xxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v3.17
Signed-off-by: Steve French <stfrench@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/cifs/smb2ops.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 870b7e763bab9..087261ca6d463 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -1145,6 +1145,12 @@ 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