From: Paulo Alcantara <palcantara@suse.de>
Subject: cifs: handle netapp error codes
Patch-mainline: Not yet, analyzing if other NetApp versions also fail
References: bsc#1136261

Some NetApp servers seem to return invalid error codes during oplock
responses. In such cases, if the client acknowledges the oplock
request and then close the file handle prior to receiving the oplock
response, the server sets an error code of either
NT_STATUS_UNSUCCESSFUL for NT codes, or DosError for DOS error codes -
which are uncomformant to the codes listed in MS-CIFS 2.2.4.32
SMB_COM_LOCKING_ANDX.

cifs.ko already ignores invalid oplock responses when it is either
NT_STATUS_INVALID_HANDLE or STATUS_SMB_BAD_FID, possibily due to
racing between open and close requests, so do the same to those NetApp
error codes.

Signed-off-by: Paulo Alcantara <palcantara@suse.de>
---
 fs/cifs/misc.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

--- a/fs/cifs/misc.c
+++ b/fs/cifs/misc.c
@@ -447,6 +447,21 @@ is_valid_oplock_break(char *buffer, stru
 		   le16_to_cpu(pSMB->hdr.Status.DosError.Error)) {
 			return true;
 		} else {
+			/*
+			 * NetApp servers seem to return invalid error codes on
+			 * response.
+			 */
+			if (pSMB->hdr.Flags2 & SMBFLG2_ERR_STATUS) {
+				if (le32_to_cpu(pSMB->hdr.Status.CifsError) == (NT_STATUS_UNSUCCESSFUL))
+					return true;
+				pr_warn_once("VFS: server returned unhandled error code on oplock response: 0x%08x\n",
+					     le32_to_cpu(pSMB->hdr.Status.CifsError));
+			} else {
+				if (le16_to_cpu(pSMB->hdr.Status.DosError.Error) == ERRgeneral)
+					return true;
+				pr_warn_once("VFS: server returned unhandled error code on oplock response: 0x%04x\n",
+					     le16_to_cpu(pSMB->hdr.Status.DosError.Error));
+			}
 			return false; /* on valid oplock brk we get "request" */
 		}
 	}