FAILED: patch "[PATCH] cifs/smb3: Fix data inconsistent when zero file range" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6b69040247e14b43419a520f841f2b3052833df9 Mon Sep 17 00:00:00 2001
From: Zhang Xiaoxu <[email protected]>
Date: Tue, 23 Jun 2020 07:31:54 -0400
Subject: [PATCH] cifs/smb3: Fix data inconsistent when zero file range

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.

index 28553d45604e..876a0d9e3d46 100644
@@ -3188,6 +3188,11 @@ static long smb3_zero_range(struct file *file, struct cifs_tcon *tcon,
 	trace_smb3_zero_enter(xid, cfile->fid.persistent_fid, tcon->tid,
 			      ses->Suid, offset, len);
 
+	/*
+	 * 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))