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, 42 insertions, 6 deletions

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 243d17696f06..cbb0d55c1267 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -166,8 +166,12 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 		retries = server->nr_targets;
 	}
 
-	if (!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;
+	}
+	spin_unlock(&ses->chan_lock);
 
 	nls_codepage = load_nls_default();
 
@@ -188,8 +192,25 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 		goto out;
 	}
 
+	/*
+	 * 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, ses);
-	if (rc == 0 && ses->need_reconnect)
+	if (!rc)
 		rc = cifs_setup_session(0, ses, nls_codepage);
 
 	/* do we need to reconnect tcon? */
@@ -198,6 +219,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 		goto out;
 	}
 
+skip_sess_setup:
 	cifs_mark_open_files_invalid(tcon);
 	rc = cifs_tree_connect(0, tcon, nls_codepage);
 	mutex_unlock(&ses->session_mutex);
@@ -337,8 +359,13 @@ static int
 smb_init_no_reconnect(int smb_command, int wct, struct cifs_tcon *tcon,
 			void **request_buf, void **response_buf)
 {
-	if (tcon->ses->need_reconnect || tcon->need_reconnect)
+	spin_lock(&tcon->ses->chan_lock);
+	if (cifs_chan_needs_reconnect(tcon->ses, tcon->ses->server) ||
+	    tcon->need_reconnect) {
+		spin_unlock(&tcon->ses->chan_lock);
 		return -EHOSTDOWN;
+	}
+	spin_unlock(&tcon->ses->chan_lock);
 
 	return __smb_init(smb_command, wct, tcon, request_buf, response_buf);
 }
@@ -600,8 +627,12 @@ CIFSSMBTDis(const unsigned int xid, struct cifs_tcon *tcon)
 	 * the tcon is no longer on the list, so no need to take lock before
 	 * checking this.
 	 */
-	if ((tcon->need_reconnect) || (tcon->ses->need_reconnect))
-		return 0;
+	spin_lock(&tcon->ses->chan_lock);
+	if ((tcon->need_reconnect) || CIFS_ALL_CHANS_NEED_RECONNECT(tcon->ses)) {
+		spin_unlock(&tcon->ses->chan_lock);
+		return -EIO;
+	}
+	spin_unlock(&tcon->ses->chan_lock);
 
 	rc = small_smb_init(SMB_COM_TREE_DISCONNECT, 0, tcon,
 			    (void **)&smb_buffer);
@@ -696,9 +727,14 @@ CIFSSMBLogoff(const unsigned int xid, struct cifs_ses *ses)
 		return -EIO;
 
 	mutex_lock(&ses->session_mutex);
-	if (ses->need_reconnect)
+	spin_lock(&ses->chan_lock);
+	if (CIFS_ALL_CHANS_NEED_RECONNECT(ses)) {
+		spin_unlock(&ses->chan_lock);
 		goto session_already_dead; /* no need to send SMBlogoff if uid
 					      already closed due to reconnect */
+	}
+	spin_unlock(&ses->chan_lock);
+
 	rc = small_smb_init(SMB_COM_LOGOFF_ANDX, 2, NULL, (void **)&pSMB);
 	if (rc) {
 		mutex_unlock(&ses->session_mutex);