cifs: track individual channel status using chans_need_reconnect

We needed a way to identify the channels under the smb session
which are in reconnect, so that the traffic to other channels
can continue. So I replaced the bool need_reconnect with
a bitmask identifying all the channels that need reconnection
(named chans_need_reconnect). When a channel needs reconnection,
the bit corresponding to the index of the server in ses->chans
is used to set this bitmask. Checking if no channels or all
the channels need reconnect then becomes very easy.

Also wrote some helper macros for checking and setting the bits.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 50 insertions, 9 deletions

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 8b3670388cda..f3b2eef36ec1 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -232,8 +232,15 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		retries = server->nr_targets;
 	}
 
-	if (!tcon->ses->need_reconnect && !tcon->need_reconnect)
+	spin_lock(&ses->chan_lock);
+	if (!cifs_chan_needs_reconnect(ses, server) && !tcon->need_reconnect) {
+		spin_unlock(&ses->chan_lock);
 		return 0;
+	}
+	cifs_dbg(FYI, "sess reconnect mask: 0x%lx, tcon reconnect: %d",
+		 tcon->ses->chans_need_reconnect,
+		 tcon->need_reconnect);
+	spin_unlock(&ses->chan_lock);
 
 	nls_codepage = load_nls_default();
 
@@ -262,8 +269,26 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		ses->binding_chan = cifs_ses_find_chan(ses, server);
 	}
 
+	/*
+	 * need to prevent multiple threads trying to simultaneously
+	 * reconnect the same SMB session
+	 */
+	spin_lock(&ses->chan_lock);
+	if (!cifs_chan_needs_reconnect(ses, server)) {
+		spin_unlock(&ses->chan_lock);
+
+		/* this just means that we only need to tcon */
+		if (tcon->need_reconnect)
+			goto skip_sess_setup;
+
+		rc = -EHOSTDOWN;
+		mutex_unlock(&ses->session_mutex);
+		goto out;
+	}
+	spin_unlock(&ses->chan_lock);
+
 	rc = cifs_negotiate_protocol(0, tcon->ses);
-	if (!rc && tcon->ses->need_reconnect) {
+	if (!rc) {
 		rc = cifs_setup_session(0, tcon->ses, nls_codepage);
 		if ((rc == -EACCES) && !tcon->retry) {
 			rc = -EHOSTDOWN;
@@ -284,6 +309,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		goto out;
 	}
 
+skip_sess_setup:
 	cifs_mark_open_files_invalid(tcon);
 	if (tcon->use_persistent)
 		tcon->need_reopen_files = true;
@@ -1359,13 +1385,19 @@ SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
 	mutex_unlock(&server->srv_mutex);
 
 	cifs_dbg(FYI, "SMB2/3 session established successfully\n");
+
+	spin_lock(&ses->chan_lock);
+	if (ses->binding)
+		cifs_chan_clear_need_reconnect(ses, ses->binding_chan->server);
+	else
+		cifs_chan_clear_need_reconnect(ses, ses->server);
+	spin_unlock(&ses->chan_lock);
+
 	/* keep existing ses state if binding */
-	if (!ses->binding) {
-		spin_lock(&GlobalMid_Lock);
+	spin_lock(&GlobalMid_Lock);
+	if (!ses->binding)
 		ses->status = CifsGood;
-		ses->need_reconnect = false;
-		spin_unlock(&GlobalMid_Lock);
-	}
+	spin_unlock(&GlobalMid_Lock);
 
 	return rc;
 }
@@ -1704,8 +1736,12 @@ SMB2_logoff(const unsigned int xid, struct cifs_ses *ses)
 		return -EIO;
 
 	/* no need to send SMB logoff if uid already closed due to reconnect */
-	if (ses->need_reconnect)
+	spin_lock(&ses->chan_lock);
+	if (CIFS_ALL_CHANS_NEED_RECONNECT(ses)) {
+		spin_unlock(&ses->chan_lock);
 		goto smb2_session_already_dead;
+	}
+	spin_unlock(&ses->chan_lock);
 
 	rc = smb2_plain_req_init(SMB2_LOGOFF, NULL, ses->server,
 				 (void **) &req, &total_len);
@@ -1913,8 +1949,13 @@ SMB2_tdis(const unsigned int xid, struct cifs_tcon *tcon)
 	if (!ses || !(ses->server))
 		return -EIO;
 
-	if ((tcon->need_reconnect) || (tcon->ses->need_reconnect))
+	spin_lock(&ses->chan_lock);
+	if ((tcon->need_reconnect) ||
+	    (CIFS_ALL_CHANS_NEED_RECONNECT(tcon->ses))) {
+		spin_unlock(&ses->chan_lock);
 		return 0;
+	}
+	spin_unlock(&ses->chan_lock);
 
 	close_cached_dir_lease(&tcon->crfid);