smb3: fix leak in "open on server" perf counter

We were not bumping up the "open on server" (num_remote_opens)
counter (in some cases) on opens of the share root so
could end up showing as a negative value.

CC: Stable <stable@vger.kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

fs/cifs/smb2ops.c

@@ -751,6 +751,8 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
 		goto oshr_exit;
 	}
 
+	atomic_inc(&tcon->num_remote_opens);
+
 	o_rsp = (struct smb2_create_rsp *)rsp_iov[0].iov_base;
 	oparms.fid->persistent_fid = o_rsp->PersistentFileId;
 	oparms.fid->volatile_fid = o_rsp->VolatileFileId;
@@ -1176,6 +1178,7 @@ smb2_set_ea(const unsigned int xid, struct cifs_tcon *tcon,
 
 	rc = compound_send_recv(xid, ses, flags, 3, rqst,
 				resp_buftype, rsp_iov);
+	/* no need to bump num_remote_opens because handle immediately closed */
 
  sea_exit:
 	kfree(ea);
@@ -1518,6 +1521,8 @@ smb2_ioctl_query_info(const unsigned int xid,
 				resp_buftype, rsp_iov);
 	if (rc)
 		goto iqinf_exit;
+
+	/* No need to bump num_remote_opens since handle immediately closed */
 	if (qi.flags & PASSTHRU_FSCTL) {
 		pqi = (struct smb_query_info __user *)arg;
 		io_rsp = (struct smb2_ioctl_rsp *)rsp_iov[1].iov_base;

fs/cifs/smb2pdu.c

@@ -2352,6 +2352,7 @@ int smb311_posix_mkdir(const unsigned int xid, struct inode *inode,
 	rqst.rq_iov = iov;
 	rqst.rq_nvec = n_iov;
 
+	/* no need to inc num_remote_opens because we close it just below */
 	trace_smb3_posix_mkdir_enter(xid, tcon->tid, ses->Suid, CREATE_NOT_FILE,
 				    FILE_WRITE_ATTRIBUTES);
 	/* resource #4: response buffer */