From: Steve French <stfrench@microsoft.com>
Date: Tue, 3 Sep 2019 17:49:46 -0500
Subject: [PATCH] smb3: log warning if CSC policy conflicts with cache mount
 option
Git-commit: cae53f70f812c845fcedb577b0d40ec97ee4b920
References: bsc#1144333
Patch-mainline: v5.4-rc1

If the server config (e.g. Samba smb.conf "csc policy = disable)
for the share indicates that the share should not be cached, log
a warning message if forced client side caching ("cache=ro" or
"cache=singleclient") is requested on mount.

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Acked-by: Paulo Alcantara <palcantara@suse.de>
---
 fs/cifs/connect.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index d9a995588c74..85f8d943a05a 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -3478,6 +3478,14 @@ cifs_get_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
 		tcon->use_resilient = true;
 	}
 
+	/* If the user really knows what they are doing they can override */
+	if (tcon->share_flags & SMB2_SHAREFLAG_NO_CACHING) {
+		if (volume_info->cache_ro)
+			cifs_dbg(VFS, "cache=ro requested on mount but NO_CACHING flag set on share\n");
+		else if (volume_info->cache_rw)
+			cifs_dbg(VFS, "cache=singleclient requested on mount but NO_CACHING flag set on share\n");
+	}
+
 	/*
 	 * We can have only one retry value for a connection to a share so for
 	 * resources mounted more than once to the same server share the last
-- 
2.25.1