four cifs/smb3 client fixes, including two for stable

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Merge tag '6.3-rc4-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull cifs client fixes from Steve French:
 "Four cifs/smb3 client (reconnect and DFS related) fixes, including two
  for stable:

   - DFS oops fix

   - DFS reconnect recursion fix

   - An SMB1 parallel reconnect fix

   - Trivial dead code removal in smb2_reconnect"

* tag '6.3-rc4-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: get rid of dead check in smb2_reconnect()
  cifs: prevent infinite recursion in CIFSGetDFSRefer()
  cifs: avoid races in parallel reconnects in smb1
  cifs: fix DFS traversal oops without CONFIG_CIFS_DFS_UPCALL

fs/cifs/cifsfs.h

@@ -124,7 +124,10 @@ extern const struct dentry_operations cifs_ci_dentry_ops;
 #ifdef CONFIG_CIFS_DFS_UPCALL
 extern struct vfsmount *cifs_dfs_d_automount(struct path *path);
 #else
-#define cifs_dfs_d_automount NULL
+static inline struct vfsmount *cifs_dfs_d_automount(struct path *path)
+{
+	return ERR_PTR(-EREMOTE);
+}
 #endif
 
 /* Functions related to symlinks */

fs/cifs/cifssmb.c

@@ -71,7 +71,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	int rc;
 	struct cifs_ses *ses;
 	struct TCP_Server_Info *server;
-	struct nls_table *nls_codepage;
+	struct nls_table *nls_codepage = NULL;
 
 	/*
 	 * SMBs NegProt, SessSetup, uLogoff do not have tcon yet so check for
@@ -99,6 +99,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	}
 	spin_unlock(&tcon->tc_lock);
 
+again:
 	rc = cifs_wait_for_server_reconnect(server, tcon->retry);
 	if (rc)
 		return rc;
@@ -110,8 +111,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	}
 	spin_unlock(&ses->chan_lock);
 
-	nls_codepage = load_nls_default();
+	mutex_lock(&ses->session_mutex);
-
 	/*
 	 * Recheck after acquire mutex. If another thread is negotiating
 	 * and the server never sends an answer the socket will be closed
@@ -120,29 +120,38 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	spin_lock(&server->srv_lock);
 	if (server->tcpStatus == CifsNeedReconnect) {
 		spin_unlock(&server->srv_lock);
+		mutex_lock(&ses->session_mutex);
+
+		if (tcon->retry)
+			goto again;
 		rc = -EHOSTDOWN;
 		goto out;
 	}
 	spin_unlock(&server->srv_lock);
 
+	nls_codepage = load_nls_default();
+
 	/*
 	 * need to prevent multiple threads trying to simultaneously
 	 * reconnect the same SMB session
 	 */
+	spin_lock(&ses->ses_lock);
 	spin_lock(&ses->chan_lock);
-	if (!cifs_chan_needs_reconnect(ses, server)) {
+	if (!cifs_chan_needs_reconnect(ses, server) &&
+	    ses->ses_status == SES_GOOD) {
 		spin_unlock(&ses->chan_lock);
+		spin_unlock(&ses->ses_lock);
 
 		/* this means that we only need to tree connect */
 		if (tcon->need_reconnect)
 			goto skip_sess_setup;
 
-		rc = -EHOSTDOWN;
+		mutex_unlock(&ses->session_mutex);
 		goto out;
 	}
 	spin_unlock(&ses->chan_lock);
+	spin_unlock(&ses->ses_lock);
 
-	mutex_lock(&ses->session_mutex);
 	rc = cifs_negotiate_protocol(0, ses, server);
 	if (!rc)
 		rc = cifs_setup_session(0, ses, server, nls_codepage);
@@ -4373,8 +4382,13 @@ CIFSGetDFSRefer(const unsigned int xid, struct cifs_ses *ses,
 		return -ENODEV;
 
 getDFSRetry:
-	rc = smb_init(SMB_COM_TRANSACTION2, 15, ses->tcon_ipc, (void **) &pSMB,
+	/*
-		      (void **) &pSMBr);
+	 * Use smb_init_no_reconnect() instead of smb_init() as
+	 * CIFSGetDFSRefer() may be called from cifs_reconnect_tcon() and thus
+	 * causing an infinite recursion.
+	 */
+	rc = smb_init_no_reconnect(SMB_COM_TRANSACTION2, 15, ses->tcon_ipc,
+				   (void **)&pSMB, (void **)&pSMBr);
 	if (rc)
 		return rc;
 

fs/cifs/smb2pdu.c

@@ -310,7 +310,6 @@ out:
 	case SMB2_READ:
 	case SMB2_WRITE:
 	case SMB2_LOCK:
-	case SMB2_IOCTL:
 	case SMB2_QUERY_DIRECTORY:
 	case SMB2_CHANGE_NOTIFY:
 	case SMB2_QUERY_INFO: