cifs: use the chans_need_reconnect bitmap for reconnect status

We use the concept of "binding" when one of the secondary channel
is in the process of connecting/reconnecting to the server. Till this
binding process completes, and the channel is bound to an existing session,
we redirect traffic from other established channels on the binding channel,
effectively blocking all traffic till individual channels get reconnected.

With my last set of commits, we can get rid of this binding serialization.
We now have a bitmap of connection states for each channel. We will use
this bitmap instead for tracking channel status.

Having a bitmap also now enables us to keep the session alive, as long
as even a single channel underneath is alive.

Unfortunately, this also meant that we need to supply the tcp connection
info for the channel during all negotiate and session setup functions.
These changes have resulted in a slightly bigger code churn.
However, I expect perf and robustness improvements in the mchan scenario
after this change.

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

1 files changed, 20 insertions, 10 deletions

diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index 2bf047b390a9..112adf153807 100644
--- a/fs/cifs/smb2transport.c
+++ b/fs/cifs/smb2transport.c
@@ -100,7 +100,8 @@ int smb2_get_sign_key(__u64 ses_id, struct TCP_Server_Info *server, u8 *key)
 	goto out;
 
 found:
-	if (ses->binding) {
+	if (cifs_chan_needs_reconnect(ses, server) &&
+	    !CIFS_ALL_CHANS_NEED_RECONNECT(ses)) {
 		/*
 		 * If we are in the process of binding a new channel
 		 * to an existing session, use the master connection
@@ -390,12 +391,18 @@ struct derivation_triplet {
 
 static int
 generate_smb3signingkey(struct cifs_ses *ses,
+			struct TCP_Server_Info *server,
 			const struct derivation_triplet *ptriplet)
 {
 	int rc;
-#ifdef CONFIG_CIFS_DEBUG_DUMP_KEYS
-	struct TCP_Server_Info *server = ses->server;
-#endif
+	bool is_binding = false;
+	int chan_index = 0;
+
+	spin_lock(&ses->chan_lock);
+	is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);
+	chan_index = cifs_ses_get_chan_index(ses, server);
+	/* TODO: introduce ref counting for channels when the can be freed */
+	spin_unlock(&ses->chan_lock);
 
 	/*
 	 * All channels use the same encryption/decryption keys but
@@ -407,10 +414,10 @@ generate_smb3signingkey(struct cifs_ses *ses,
 	 * master connection signing key stored in the session
 	 */
 
-	if (ses->binding) {
+	if (is_binding) {
 		rc = generate_key(ses, ptriplet->signing.label,
 				  ptriplet->signing.context,
-				  cifs_ses_binding_channel(ses)->signkey,
+				  ses->chans[chan_index].signkey,
 				  SMB3_SIGN_KEY_SIZE);
 		if (rc)
 			return rc;
@@ -422,6 +429,7 @@ generate_smb3signingkey(struct cifs_ses *ses,
 		if (rc)
 			return rc;
 
+		/* safe to access primary channel, since it will never go away */
 		memcpy(ses->chans[0].signkey, ses->smb3signingkey,
 		       SMB3_SIGN_KEY_SIZE);
 
@@ -470,7 +478,8 @@ generate_smb3signingkey(struct cifs_ses *ses,
 }
 
 int
-generate_smb30signingkey(struct cifs_ses *ses)
+generate_smb30signingkey(struct cifs_ses *ses,
+			 struct TCP_Server_Info *server)
 
 {
 	struct derivation_triplet triplet;
@@ -494,11 +503,12 @@ generate_smb30signingkey(struct cifs_ses *ses)
 	d->context.iov_base = "ServerOut";
 	d->context.iov_len = 10;
 
-	return generate_smb3signingkey(ses, &triplet);
+	return generate_smb3signingkey(ses, server, &triplet);
 }
 
 int
-generate_smb311signingkey(struct cifs_ses *ses)
+generate_smb311signingkey(struct cifs_ses *ses,
+			  struct TCP_Server_Info *server)
 
 {
 	struct derivation_triplet triplet;
@@ -522,7 +532,7 @@ generate_smb311signingkey(struct cifs_ses *ses)
 	d->context.iov_base = ses->preauth_sha_hash;
 	d->context.iov_len = 64;
 
-	return generate_smb3signingkey(ses, &triplet);
+	return generate_smb3signingkey(ses, server, &triplet);
 }
 
 int