cifs: silence compiler warnings showing up with gcc-4.7.0

gcc-4.7.0 has started throwing these warnings when building cifs.ko.

  CC [M]  fs/cifs/cifssmb.o
fs/cifs/cifssmb.c: In function ‘CIFSSMBSetCIFSACL’:
fs/cifs/cifssmb.c:3905:9: warning: array subscript is above array bounds [-Warray-bounds]
fs/cifs/cifssmb.c: In function ‘CIFSSMBSetFileInfo’:
fs/cifs/cifssmb.c:5711:8: warning: array subscript is above array bounds [-Warray-bounds]
fs/cifs/cifssmb.c: In function ‘CIFSSMBUnixSetFileInfo’:
fs/cifs/cifssmb.c:6001:25: warning: array subscript is above array bounds [-Warray-bounds]

This patch cleans up the code a bit by using the offsetof macro instead
of the funky "&pSMB->hdr.Protocol" construct.
Signed-off-by: NJeff Layton <jlayton@redhat.com>
Signed-off-by: NSteve French <sfrench@us.ibm.com>

fs/cifs/cifssmb.c

@@ -3892,13 +3892,12 @@ CIFSSMBSetCIFSACL(const int xid, struct cifs_tcon *tcon, __u16 fid,
 	int rc = 0;
 	int bytes_returned = 0;
 	SET_SEC_DESC_REQ *pSMB = NULL;
-	NTRANSACT_RSP *pSMBr = NULL;
+	void *pSMBr;
 
 setCifsAclRetry:
-	rc = smb_init(SMB_COM_NT_TRANSACT, 19, tcon, (void **) &pSMB,
-			(void **) &pSMBr);
+	rc = smb_init(SMB_COM_NT_TRANSACT, 19, tcon, (void **) &pSMB, &pSMBr);
 	if (rc)
-			return (rc);
+		return rc;
 
 	pSMB->MaxSetupCount = 0;
 	pSMB->Reserved = 0;
@@ -3926,9 +3925,8 @@ CIFSSMBSetCIFSACL(const int xid, struct cifs_tcon *tcon, __u16 fid,
 	pSMB->AclFlags = cpu_to_le32(aclflag);
 
 	if (pntsd && acllen) {
-		memcpy((char *) &pSMBr->hdr.Protocol + data_offset,
-			(char *) pntsd,
-			acllen);
+		memcpy((char *)pSMBr + offsetof(struct smb_hdr, Protocol) +
+				data_offset, pntsd, acllen);
 		inc_rfc1001_len(pSMB, byte_count + data_count);
 	} else
 		inc_rfc1001_len(pSMB, byte_count);
@@ -5708,7 +5706,8 @@ CIFSSMBSetFileInfo(const int xid, struct cifs_tcon *tcon,
 	param_offset = offsetof(struct smb_com_transaction2_sfi_req, Fid) - 4;
 	offset = param_offset + params;
 
-	data_offset = (char *) (&pSMB->hdr.Protocol) + offset;
+	data_offset = (char *)pSMB +
+			offsetof(struct smb_hdr, Protocol) + offset;
 
 	count = sizeof(FILE_BASIC_INFO);
 	pSMB->MaxParameterCount = cpu_to_le16(2);
@@ -5977,7 +5976,7 @@ CIFSSMBUnixSetFileInfo(const int xid, struct cifs_tcon *tcon,
 		       u16 fid, u32 pid_of_opener)
 {
 	struct smb_com_transaction2_sfi_req *pSMB  = NULL;
-	FILE_UNIX_BASIC_INFO *data_offset;
+	char *data_offset;
 	int rc = 0;
 	u16 params, param_offset, offset, byte_count, count;
 
@@ -5999,8 +5998,9 @@ CIFSSMBUnixSetFileInfo(const int xid, struct cifs_tcon *tcon,
 	param_offset = offsetof(struct smb_com_transaction2_sfi_req, Fid) - 4;
 	offset = param_offset + params;
 
-	data_offset = (FILE_UNIX_BASIC_INFO *)
-				((char *)(&pSMB->hdr.Protocol) + offset);
+	data_offset = (char *)pSMB +
+			offsetof(struct smb_hdr, Protocol) + offset;
+
 	count = sizeof(FILE_UNIX_BASIC_INFO);
 
 	pSMB->MaxParameterCount = cpu_to_le16(2);
@@ -6022,7 +6022,7 @@ CIFSSMBUnixSetFileInfo(const int xid, struct cifs_tcon *tcon,
 	inc_rfc1001_len(pSMB, byte_count);
 	pSMB->ByteCount = cpu_to_le16(byte_count);
 
-	cifs_fill_unix_set_info(data_offset, args);
+	cifs_fill_unix_set_info((FILE_UNIX_BASIC_INFO *)data_offset, args);
 
 	rc = SendReceiveNoRsp(xid, tcon->ses, (char *) pSMB, 0);
 	if (rc)