Merge tag '5.17-rc-part1-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull cifs updates from Steve French:

 - multichannel patches mostly related to improving reconnect behavior

 - minor cleanup patches

* tag '5.17-rc-part1-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: fix FILE_BOTH_DIRECTORY_INFO definition
  cifs: move superblock magic defitions to magic.h
  cifs: Fix smb311_update_preauth_hash() kernel-doc comment
  cifs: avoid race during socket reconnect between send and recv
  cifs: maintain a state machine for tcp/smb/tcon sessions
  cifs: fix hang on cifs_get_next_mid()
  cifs: take cifs_tcp_ses_lock for status checks
  cifs: reconnect only the connection and not smb session where possible
  cifs: add WARN_ON for when chan_count goes below minimum
  cifs: adjust DebugData to use chans_need_reconnect for conn status
  cifs: use the chans_need_reconnect bitmap for reconnect status
  cifs: track individual channel status using chans_need_reconnect
  cifs: remove redundant assignment to pointer p

23 files changed, 723 insertions, 325 deletions

diff --git a/fs/cifs/cifs_debug.c b/fs/cifs/cifs_debug.c
index d282caf9f037..ea00e1a91250 100644
--- a/fs/cifs/cifs_debug.c
+++ b/fs/cifs/cifs_debug.c
@@ -416,11 +416,17 @@ skip_rdma:
 				   from_kuid(&init_user_ns, ses->cred_uid));
 
 			spin_lock(&ses->chan_lock);
+			if (CIFS_CHAN_NEEDS_RECONNECT(ses, 0))
+				seq_puts(m, "\tPrimary channel: DISCONNECTED ");
+
 			if (ses->chan_count > 1) {
 				seq_printf(m, "\n\n\tExtra Channels: %zu ",
 					   ses->chan_count-1);
-				for (j = 1; j < ses->chan_count; j++)
+				for (j = 1; j < ses->chan_count; j++) {
 					cifs_dump_channel(m, j, &ses->chans[j]);
+					if (CIFS_CHAN_NEEDS_RECONNECT(ses, j))
+						seq_puts(m, "\tDISCONNECTED ");
+				}
 			}
 			spin_unlock(&ses->chan_lock);
 
diff --git a/fs/cifs/cifs_spnego.c b/fs/cifs/cifs_spnego.c
index 353bd0dd7026..342717bf1dc2 100644
--- a/fs/cifs/cifs_spnego.c
+++ b/fs/cifs/cifs_spnego.c
@@ -84,9 +84,9 @@ struct key_type cifs_spnego_key_type = {
 
 /* get a key struct with a SPNEGO security blob, suitable for session setup */
 struct key *
-cifs_get_spnego_key(struct cifs_ses *sesInfo)
+cifs_get_spnego_key(struct cifs_ses *sesInfo,
+		    struct TCP_Server_Info *server)
 {
-	struct TCP_Server_Info *server = cifs_ses_server(sesInfo);
 	struct sockaddr_in *sa = (struct sockaddr_in *) &server->dstaddr;
 	struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *) &server->dstaddr;
 	char *description, *dp;
diff --git a/fs/cifs/cifs_spnego.h b/fs/cifs/cifs_spnego.h
index e6a0451877d4..7f102ffeb675 100644
--- a/fs/cifs/cifs_spnego.h
+++ b/fs/cifs/cifs_spnego.h
@@ -29,7 +29,8 @@ struct cifs_spnego_msg {
 
 #ifdef __KERNEL__
 extern struct key_type cifs_spnego_key_type;
-extern struct key *cifs_get_spnego_key(struct cifs_ses *sesInfo);
+extern struct key *cifs_get_spnego_key(struct cifs_ses *sesInfo,
+				       struct TCP_Server_Info *server);
 #endif /* KERNEL */
 
 #endif /* _CIFS_SPNEGO_H */
diff --git a/fs/cifs/cifs_swn.c b/fs/cifs/cifs_swn.c
index 23a1ed2fb769..8f386dd9939e 100644
--- a/fs/cifs/cifs_swn.c
+++ b/fs/cifs/cifs_swn.c
@@ -498,10 +498,10 @@ static int cifs_swn_reconnect(struct cifs_tcon *tcon, struct sockaddr_storage *a
 		goto unlock;
 	}
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	if (tcon->ses->server->tcpStatus != CifsExiting)
 		tcon->ses->server->tcpStatus = CifsNeedReconnect;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 unlock:
 	mutex_unlock(&tcon->ses->server->srv_mutex);
diff --git a/fs/cifs/cifsencrypt.c b/fs/cifs/cifsencrypt.c
index d118282071b3..0912d8bbbac1 100644
--- a/fs/cifs/cifsencrypt.c
+++ b/fs/cifs/cifsencrypt.c
@@ -141,9 +141,13 @@ int cifs_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server,
 	if ((cifs_pdu == NULL) || (server == NULL))
 		return -EINVAL;
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (!(cifs_pdu->Flags2 & SMBFLG2_SECURITY_SIGNATURE) ||
-	    server->tcpStatus == CifsNeedNegotiate)
+	    server->tcpStatus == CifsNeedNegotiate) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return rc;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	if (!server->session_estab) {
 		memcpy(cifs_pdu->Signature.SecuritySignature, "BSRSPYL", 8);
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index dca42aa87d30..36b2e0cb9736 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -26,6 +26,7 @@
 #include <linux/random.h>
 #include <linux/uuid.h>
 #include <linux/xattr.h>
+#include <uapi/linux/magic.h>
 #include <net/ipv6.h>
 #include "cifsfs.h"
 #include "cifspdu.h"
@@ -202,7 +203,7 @@ cifs_read_super(struct super_block *sb)
 		sb->s_time_max = ts.tv_sec;
 	}
 
-	sb->s_magic = CIFS_MAGIC_NUMBER;
+	sb->s_magic = CIFS_SUPER_MAGIC;
 	sb->s_op = &cifs_super_ops;
 	sb->s_xattr = cifs_xattr_handlers;
 	rc = super_setup_bdi(sb);
@@ -773,7 +774,7 @@ cifs_get_root(struct smb3_fs_context *ctx, struct super_block *sb)
 
 	sep = CIFS_DIR_SEP(cifs_sb);
 	dentry = dget(sb->s_root);
-	p = s = full_path;
+	s = full_path;
 
 	do {
 		struct inode *dir = d_inode(dentry);
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index be74606724c7..f84978b76bb6 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -24,8 +24,6 @@
 #include "../smbfs_common/smb2pdu.h"
 #include "smb2pdu.h"
 
-#define CIFS_MAGIC_NUMBER 0xFF534D42      /* the first four bytes of SMB PDUs */
-
 #define SMB_PATH_MAX 260
 #define CIFS_PORT 445
 #define RFC1001_PORT 139
@@ -113,7 +111,13 @@ enum statusEnum {
 	CifsGood,
 	CifsExiting,
 	CifsNeedReconnect,
-	CifsNeedNegotiate
+	CifsNeedNegotiate,
+	CifsInNegotiate,
+	CifsNeedSessSetup,
+	CifsInSessSetup,
+	CifsNeedTcon,
+	CifsInTcon,
+	CifsInFilesInvalidate
 };
 
 enum securityEnum {
@@ -263,13 +267,16 @@ struct smb_version_operations {
 	/* check if we need to negotiate */
 	bool (*need_neg)(struct TCP_Server_Info *);
 	/* negotiate to the server */
-	int (*negotiate)(const unsigned int, struct cifs_ses *);
+	int (*negotiate)(const unsigned int xid,
+			 struct cifs_ses *ses,
+			 struct TCP_Server_Info *server);
 	/* set negotiated write size */
 	unsigned int (*negotiate_wsize)(struct cifs_tcon *tcon, struct smb3_fs_context *ctx);
 	/* set negotiated read size */
 	unsigned int (*negotiate_rsize)(struct cifs_tcon *tcon, struct smb3_fs_context *ctx);
 	/* setup smb sessionn */
 	int (*sess_setup)(const unsigned int, struct cifs_ses *,
+			  struct TCP_Server_Info *server,
 			  const struct nls_table *);
 	/* close smb session */
 	int (*logoff)(const unsigned int, struct cifs_ses *);
@@ -414,7 +421,8 @@ struct smb_version_operations {
 	void (*set_lease_key)(struct inode *, struct cifs_fid *);
 	/* generate new lease key */
 	void (*new_lease_key)(struct cifs_fid *);
-	int (*generate_signingkey)(struct cifs_ses *);
+	int (*generate_signingkey)(struct cifs_ses *ses,
+				   struct TCP_Server_Info *server);
 	int (*calc_signature)(struct smb_rqst *, struct TCP_Server_Info *,
 				bool allocate_crypto);
 	int (*set_integrity)(const unsigned int, struct cifs_tcon *tcon,
@@ -582,7 +590,7 @@ struct TCP_Server_Info {
 	char server_RFC1001_name[RFC1001_NAME_LEN_WITH_NULL];
 	struct smb_version_operations	*ops;
 	struct smb_version_values	*vals;
-	/* updates to tcpStatus protected by GlobalMid_Lock */
+	/* updates to tcpStatus protected by cifs_tcp_ses_lock */
 	enum statusEnum tcpStatus; /* what we think the status is */
 	char *hostname; /* hostname portion of UNC string */
 	struct socket *ssocket;
@@ -920,7 +928,7 @@ struct cifs_ses {
 	struct mutex session_mutex;
 	struct TCP_Server_Info *server;	/* pointer to server info */
 	int ses_count;		/* reference counter */
-	enum statusEnum status;  /* updates protected by GlobalMid_Lock */
+	enum statusEnum status;  /* updates protected by cifs_tcp_ses_lock */
 	unsigned overrideSecFlg;  /* if non-zero override global sec flags */
 	char *serverOS;		/* name of operating system underlying server */
 	char *serverNOS;	/* name of network operating system of server */
@@ -939,17 +947,13 @@ struct cifs_ses {
 	struct ntlmssp_auth *ntlmssp; /* ciphertext, flags, server challenge */
 	enum securityEnum sectype; /* what security flavor was specified? */
 	bool sign;		/* is signing required? */
-	bool need_reconnect:1; /* connection reset, uid now invalid */
 	bool domainAuto:1;
-	bool binding:1; /* are we binding the session? */
 	__u16 session_flags;
 	__u8 smb3signingkey[SMB3_SIGN_KEY_SIZE];
 	__u8 smb3encryptionkey[SMB3_ENC_DEC_KEY_SIZE];
 	__u8 smb3decryptionkey[SMB3_ENC_DEC_KEY_SIZE];
 	__u8 preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
 
-	__u8 binding_preauth_sha_hash[SMB2_PREAUTH_HASH_SIZE];
-
 	/*
 	 * Network interfaces available on the server this session is
 	 * connected to.
@@ -969,45 +973,34 @@ struct cifs_ses {
 	spinlock_t chan_lock;
 	/* ========= begin: protected by chan_lock ======== */
 #define CIFS_MAX_CHANNELS 16
+#define CIFS_ALL_CHANNELS_SET(ses)	\
+	((1UL << (ses)->chan_count) - 1)
+#define CIFS_ALL_CHANS_NEED_RECONNECT(ses)	\
+	((ses)->chans_need_reconnect == CIFS_ALL_CHANNELS_SET(ses))
+#define CIFS_SET_ALL_CHANS_NEED_RECONNECT(ses)	\
+	((ses)->chans_need_reconnect = CIFS_ALL_CHANNELS_SET(ses))
+#define CIFS_CHAN_NEEDS_RECONNECT(ses, index)	\
+	test_bit((index), &(ses)->chans_need_reconnect)
+
 	struct cifs_chan chans[CIFS_MAX_CHANNELS];
-	struct cifs_chan *binding_chan;
 	size_t chan_count;
 	size_t chan_max;
 	atomic_t chan_seq; /* round robin state */
+
+	/*
+	 * chans_need_reconnect is a bitmap indicating which of the channels
+	 * under this smb session needs to be reconnected.
+	 * If not multichannel session, only one bit will be used.
+	 *
+	 * We will ask for sess and tcon reconnection only if all the
+	 * channels are marked for needing reconnection. This will
+	 * enable the sessions on top to continue to live till any
+	 * of the channels below are active.
+	 */
+	unsigned long chans_need_reconnect;
 	/* ========= end: protected by chan_lock ======== */
 };
 
-/*
- * When binding a new channel, we need to access the channel which isn't fully
- * established yet.
- */
-
-static inline
-struct cifs_chan *cifs_ses_binding_channel(struct cifs_ses *ses)
-{
-	if (ses->binding)
-		return ses->binding_chan;
-	else
-		return NULL;
-}
-
-/*
- * Returns the server pointer of the session. When binding a new
- * channel this returns the last channel which isn't fully established
- * yet.
- *
- * This function should be use for negprot/sess.setup codepaths. For
- * the other requests see cifs_pick_channel().
- */
-static inline
-struct TCP_Server_Info *cifs_ses_server(struct cifs_ses *ses)
-{
-	if (ses->binding)
-		return ses->binding_chan->server;
-	else
-		return ses->server;
-}
-
 static inline bool
 cap_unix(struct cifs_ses *ses)
 {
diff --git a/fs/cifs/cifspdu.h b/fs/cifs/cifspdu.h
index d2ff438fd31f..68b9a436af4b 100644
--- a/fs/cifs/cifspdu.h
+++ b/fs/cifs/cifspdu.h
@@ -2560,7 +2560,7 @@ typedef struct {
 	__le32 EaSize; /* length of the xattrs */
 	__u8   ShortNameLength;
 	__u8   Reserved;
-	__u8   ShortName[12];
+	__u8   ShortName[24];
 	char FileName[1];
 } __attribute__((packed)) FILE_BOTH_DIRECTORY_INFO; /* level 0x104 FFrsp data */
 
diff --git a/fs/cifs/cifsproto.h b/fs/cifs/cifsproto.h
index 4f5a3e857df4..e0dc147e69a8 100644
--- a/fs/cifs/cifsproto.h
+++ b/fs/cifs/cifsproto.h
@@ -131,7 +131,8 @@ extern int SendReceiveBlockingLock(const unsigned int xid,
 			struct smb_hdr *in_buf ,
 			struct smb_hdr *out_buf,
 			int *bytes_returned);
-extern int cifs_reconnect(struct TCP_Server_Info *server);
+extern int cifs_reconnect(struct TCP_Server_Info *server,
+			  bool mark_smb_session);
 extern int checkSMB(char *buf, unsigned int len, struct TCP_Server_Info *srvr);
 extern bool is_valid_oplock_break(char *, struct TCP_Server_Info *);
 extern bool backup_cred(struct cifs_sb_info *);
@@ -164,6 +165,7 @@ extern int small_smb_init_no_tc(const int smb_cmd, const int wct,
 extern enum securityEnum select_sectype(struct TCP_Server_Info *server,
 				enum securityEnum requested);
 extern int CIFS_SessSetup(const unsigned int xid, struct cifs_ses *ses,
+			  struct TCP_Server_Info *server,
 			  const struct nls_table *nls_cp);
 extern struct timespec64 cifs_NTtimeToUnix(__le64 utc_nanoseconds_since_1601);
 extern u64 cifs_UnixTimeToNT(struct timespec64);
@@ -293,11 +295,15 @@ extern int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon,
 			     const struct nls_table *nlsc);
 
 extern int cifs_negotiate_protocol(const unsigned int xid,
-				   struct cifs_ses *ses);
+				   struct cifs_ses *ses,
+				   struct TCP_Server_Info *server);
 extern int cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
+			      struct TCP_Server_Info *server,
 			      struct nls_table *nls_info);
 extern int cifs_enable_signing(struct TCP_Server_Info *server, bool mnt_sign_required);
-extern int CIFSSMBNegotiate(const unsigned int xid, struct cifs_ses *ses);
+extern int CIFSSMBNegotiate(const unsigned int xid,
+			    struct cifs_ses *ses,
+			    struct TCP_Server_Info *server);
 
 extern int CIFSTCon(const unsigned int xid, struct cifs_ses *ses,
 		    const char *tree, struct cifs_tcon *tcon,
@@ -504,8 +510,10 @@ extern int cifs_verify_signature(struct smb_rqst *rqst,
 extern int setup_ntlmv2_rsp(struct cifs_ses *, const struct nls_table *);
 extern void cifs_crypto_secmech_release(struct TCP_Server_Info *server);
 extern int calc_seckey(struct cifs_ses *);
-extern int generate_smb30signingkey(struct cifs_ses *);
-extern int generate_smb311signingkey(struct cifs_ses *);
+extern int generate_smb30signingkey(struct cifs_ses *ses,
+				    struct TCP_Server_Info *server);
+extern int generate_smb311signingkey(struct cifs_ses *ses,
+				     struct TCP_Server_Info *server);
 
 extern int CIFSSMBCopy(unsigned int xid,
 			struct cifs_tcon *source_tcon,
@@ -601,6 +609,19 @@ bool is_server_using_iface(struct TCP_Server_Info *server,
 bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface);
 void cifs_ses_mark_for_reconnect(struct cifs_ses *ses);
 
+unsigned int
+cifs_ses_get_chan_index(struct cifs_ses *ses,
+			struct TCP_Server_Info *server);
+void
+cifs_chan_set_need_reconnect(struct cifs_ses *ses,
+			     struct TCP_Server_Info *server);
+void
+cifs_chan_clear_need_reconnect(struct cifs_ses *ses,
+			       struct TCP_Server_Info *server);
+bool
+cifs_chan_needs_reconnect(struct cifs_ses *ses,
+			  struct TCP_Server_Info *server);
+
 void extract_unc_hostname(const char *unc, const char **h, size_t *len);
 int copy_path_name(char *dst, const char *src);
 int smb2_parse_query_directory(struct cifs_tcon *tcon, struct kvec *rsp_iov,
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 243d17696f06..071e2f21a7db 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -73,6 +73,16 @@ cifs_mark_open_files_invalid(struct cifs_tcon *tcon)
 	struct list_head *tmp;
 	struct list_head *tmp1;
 
+	/* only send once per connect */
+	spin_lock(&cifs_tcp_ses_lock);
+	if (tcon->ses->status != CifsGood ||
+	    tcon->tidStatus != CifsNeedReconnect) {
+		spin_unlock(&cifs_tcp_ses_lock);
+		return;
+	}
+	tcon->tidStatus = CifsInFilesInvalidate;
+	spin_unlock(&cifs_tcp_ses_lock);
+
 	/* list all files open on tree connection and mark them invalid */
 	spin_lock(&tcon->open_file_lock);
 	list_for_each_safe(tmp, tmp1, &tcon->openFileList) {
@@ -89,6 +99,11 @@ cifs_mark_open_files_invalid(struct cifs_tcon *tcon)
 	memset(tcon->crfid.fid, 0, sizeof(struct cifs_fid));
 	mutex_unlock(&tcon->crfid.fid_mutex);
 
+	spin_lock(&cifs_tcp_ses_lock);
+	if (tcon->tidStatus == CifsInFilesInvalidate)
+		tcon->tidStatus = CifsNeedTcon;
+	spin_unlock(&cifs_tcp_ses_lock);
+
 	/*
 	 * BB Add call to invalidate_inodes(sb) for all superblocks mounted
 	 * to this tcon.
@@ -120,15 +135,18 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 	 * only tree disconnect, open, and write, (and ulogoff which does not
 	 * have tcon) are allowed as we start force umount
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if (tcon->tidStatus == CifsExiting) {
 		if (smb_command != SMB_COM_WRITE_ANDX &&
 		    smb_command != SMB_COM_OPEN_ANDX &&
 		    smb_command != SMB_COM_TREE_DISCONNECT) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			cifs_dbg(FYI, "can not send cmd %d while umounting\n",
 				 smb_command);
 			return -ENODEV;
 		}
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	retries = server->nr_targets;
 
@@ -148,8 +166,12 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
 		}
 
 		/* are we still trying to reconnect? */
-		if (server->tcpStatus != CifsNeedReconnect)
+		spin_lock(&cifs_tcp_ses_lock);
+		if (server->tcpStatus != CifsNeedReconnect) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			break;
+		}
+		spin_unlock(&cifs_tcp_ses_lock);
 
 		if (retries && --retries)
 			continue;
@@ -166,31 +188,49 @@ 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();
 
 	/*
-	 * need to prevent multiple threads trying to simultaneously
-	 * reconnect the same SMB session
-	 */
-	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
 	 * and tcpStatus set to reconnect.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedReconnect) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		rc = -EHOSTDOWN;
-		mutex_unlock(&ses->session_mutex);
 		goto out;
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
-	rc = cifs_negotiate_protocol(0, ses);
-	if (rc == 0 && ses->need_reconnect)
-		rc = cifs_setup_session(0, ses, nls_codepage);
+	/*
+	 * 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 means that we only need to tree connect */
+		if (tcon->need_reconnect)
+			goto skip_sess_setup;
+
+		rc = -EHOSTDOWN;
+		goto out;
+	}
+	spin_unlock(&ses->chan_lock);
+
+	mutex_lock(&ses->session_mutex);
+	rc = cifs_negotiate_protocol(0, ses, server);
+	if (!rc)
+		rc = cifs_setup_session(0, ses, server, nls_codepage);
 
 	/* do we need to reconnect tcon? */
 	if (rc || !tcon->need_reconnect) {
@@ -198,6 +238,7 @@ 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 +378,13 @@ 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);
 }
@@ -476,14 +522,15 @@ should_set_ext_sec_flag(enum securityEnum sectype)
 }
 
 int
-CIFSSMBNegotiate(const unsigned int xid, struct cifs_ses *ses)
+CIFSSMBNegotiate(const unsigned int xid,
+		 struct cifs_ses *ses,
+		 struct TCP_Server_Info *server)
 {
 	NEGOTIATE_REQ *pSMB;
 	NEGOTIATE_RSP *pSMBr;
 	int rc = 0;
 	int bytes_returned;
 	int i;
-	struct TCP_Server_Info *server = ses->server;
 	u16 count;
 
 	if (!server) {
@@ -600,8 +647,12 @@ 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 +747,14 @@ 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);
@@ -1401,7 +1457,7 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 
 	if (server->ops->is_session_expired &&
 	    server->ops->is_session_expired(buf)) {
-		cifs_reconnect(server);
+		cifs_reconnect(server, true);
 		return -1;
 	}
 
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 68ed29cff7e8..0f36deff790e 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -166,14 +166,17 @@ static void cifs_resolve_server(struct work_struct *work)
  * Mark all sessions and tcons for reconnect.
  *
  * @server needs to be previously set to CifsNeedReconnect.
+ *
  */
-static void cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server)
+static void
+cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server,
+				      bool mark_smb_session)
 {
+	struct TCP_Server_Info *pserver;
 	struct cifs_ses *ses;
 	struct cifs_tcon *tcon;
 	struct mid_q_entry *mid, *nmid;
 	struct list_head retry_list;
-	struct TCP_Server_Info *pserver;
 
 	server->maxBuf = 0;
 	server->max_read = 0;
@@ -191,16 +194,37 @@ static void cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server
 
 	spin_lock(&cifs_tcp_ses_lock);
 	list_for_each_entry(ses, &pserver->smb_ses_list, smb_ses_list) {
-		ses->need_reconnect = true;
-		list_for_each_entry(tcon, &ses->tcon_list, tcon_list)
+		spin_lock(&ses->chan_lock);
+		if (!mark_smb_session && cifs_chan_needs_reconnect(ses, server))
+			goto next_session;
+
+		cifs_chan_set_need_reconnect(ses, server);
+
+		/* If all channels need reconnect, then tcon needs reconnect */
+		if (!mark_smb_session && !CIFS_ALL_CHANS_NEED_RECONNECT(ses))
+			goto next_session;
+
+		ses->status = CifsNeedReconnect;
+
+		list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
 			tcon->need_reconnect = true;
+			tcon->tidStatus = CifsNeedReconnect;
+		}
 		if (ses->tcon_ipc)
 			ses->tcon_ipc->need_reconnect = true;
+
+next_session:
+		spin_unlock(&ses->chan_lock);
 	}
 	spin_unlock(&cifs_tcp_ses_lock);
 
+	/*
+	 * before reconnecting the tcp session, mark the smb session (uid)
+	 * and the tid bad so they are not used until reconnected
+	 */
+	cifs_dbg(FYI, "%s: marking sessions and tcons for reconnect and tearing down socket\n",
+		 __func__);
 	/* do not want to be sending data on a socket we are freeing */
-	cifs_dbg(FYI, "%s: tearing down socket\n", __func__);
 	mutex_lock(&server->srv_mutex);
 	if (server->ssocket) {
 		cifs_dbg(FYI, "State: 0x%x Flags: 0x%lx\n", server->ssocket->state,
@@ -248,16 +272,16 @@ static void cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server
 
 static bool cifs_tcp_ses_needs_reconnect(struct TCP_Server_Info *server, int num_targets)
 {
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	server->nr_targets = num_targets;
 	if (server->tcpStatus == CifsExiting) {
 		/* the demux thread will exit normally next time through the loop */
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&cifs_tcp_ses_lock);
 		wake_up(&server->response_q);
 		return false;
 	}
 	server->tcpStatus = CifsNeedReconnect;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 	return true;
 }
 
@@ -268,15 +292,21 @@ static bool cifs_tcp_ses_needs_reconnect(struct TCP_Server_Info *server, int num
  * mark all smb sessions as reconnecting for tcp session
  * reconnect tcp session
  * wake up waiters on reconnection? - (not needed currently)
+ *
+ * if mark_smb_session is passed as true, unconditionally mark
+ * the smb session (and tcon) for reconnect as well. This value
+ * doesn't really matter for non-multichannel scenario.
+ *
  */
-static int __cifs_reconnect(struct TCP_Server_Info *server)
+static int __cifs_reconnect(struct TCP_Server_Info *server,
+			    bool mark_smb_session)
 {
 	int rc = 0;
 
 	if (!cifs_tcp_ses_needs_reconnect(server, 1))
 		return 0;
 
-	cifs_mark_tcp_ses_conns_for_reconnect(server);
+	cifs_mark_tcp_ses_conns_for_reconnect(server, mark_smb_session);
 
 	do {
 		try_to_freeze();
@@ -299,10 +329,10 @@ static int __cifs_reconnect(struct TCP_Server_Info *server)
 		} else {
 			atomic_inc(&tcpSesReconnectCount);
 			set_credits(server, 1);
-			spin_lock(&GlobalMid_Lock);
+			spin_lock(&cifs_tcp_ses_lock);
 			if (server->tcpStatus != CifsExiting)
 				server->tcpStatus = CifsNeedNegotiate;
-			spin_unlock(&GlobalMid_Lock);
+			spin_unlock(&cifs_tcp_ses_lock);
 			cifs_swn_reset_server_dstaddr(server);
 			mutex_unlock(&server->srv_mutex);
 		}
@@ -371,7 +401,9 @@ static int reconnect_target_unlocked(struct TCP_Server_Info *server, struct dfs_
 	return rc;
 }
 
-static int reconnect_dfs_server(struct TCP_Server_Info *server)
+static int
+reconnect_dfs_server(struct TCP_Server_Info *server,
+		     bool mark_smb_session)
 {
 	int rc = 0;
 	const char *refpath = server->current_fullpath + 1;
@@ -395,7 +427,7 @@ static int reconnect_dfs_server(struct TCP_Server_Info *server)
 	if (!cifs_tcp_ses_needs_reconnect(server, num_targets))
 		return 0;
 
-	cifs_mark_tcp_ses_conns_for_reconnect(server);
+	cifs_mark_tcp_ses_conns_for_reconnect(server, mark_smb_session);
 
 	do {
 		try_to_freeze();
@@ -416,10 +448,10 @@ static int reconnect_dfs_server(struct TCP_Server_Info *server)
 		 */
 		atomic_inc(&tcpSesReconnectCount);
 		set_credits(server, 1);
-		spin_lock(&GlobalMid_Lock);
+		spin_lock(&cifs_tcp_ses_lock);
 		if (server->tcpStatus != CifsExiting)
 			server->tcpStatus = CifsNeedNegotiate;
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&cifs_tcp_ses_lock);
 		cifs_swn_reset_server_dstaddr(server);
 		mutex_unlock(&server->srv_mutex);
 	} while (server->tcpStatus == CifsNeedReconnect);
@@ -430,29 +462,32 @@ static int reconnect_dfs_server(struct TCP_Server_Info *server)
 	dfs_cache_free_tgts(&tl);
 
 	/* Need to set up echo worker again once connection has been established */
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedNegotiate)
 		mod_delayed_work(cifsiod_wq, &server->echo, 0);
 
+	spin_unlock(&cifs_tcp_ses_lock);
+
 	wake_up(&server->response_q);
 	return rc;
 }
 
-int cifs_reconnect(struct TCP_Server_Info *server)
+int cifs_reconnect(struct TCP_Server_Info *server, bool mark_smb_session)
 {
 	/* If tcp session is not an dfs connection, then reconnect to last target server */
 	spin_lock(&cifs_tcp_ses_lock);
 	if (!server->is_dfs_conn || !server->origin_fullpath || !server->leaf_fullpath) {
 		spin_unlock(&cifs_tcp_ses_lock);
-		return __cifs_reconnect(server);
+		return __cifs_reconnect(server, mark_smb_session);
 	}
 	spin_unlock(&cifs_tcp_ses_lock);
 
-	return reconnect_dfs_server(server);
+	return reconnect_dfs_server(server, mark_smb_session);
 }
 #else
-int cifs_reconnect(struct TCP_Server_Info *server)
+int cifs_reconnect(struct TCP_Server_Info *server, bool mark_smb_session)
 {
-	return __cifs_reconnect(server);
+	return __cifs_reconnect(server, mark_smb_session);
 }
 #endif
 
@@ -534,15 +569,18 @@ server_unresponsive(struct TCP_Server_Info *server)
 	 * 65s kernel_recvmsg times out, and we see that we haven't gotten
 	 *     a response in >60s.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if ((server->tcpStatus == CifsGood ||
 	    server->tcpStatus == CifsNeedNegotiate) &&
 	    (!server->ops->can_echo || server->ops->can_echo(server)) &&
 	    time_after(jiffies, server->lstrp + 3 * server->echo_interval)) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		cifs_server_dbg(VFS, "has not responded in %lu seconds. Reconnecting...\n",
 			 (3 * server->echo_interval) / HZ);
-		cifs_reconnect(server);
+		cifs_reconnect(server, false);
 		return true;
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	return false;
 }
@@ -576,7 +614,7 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
 
 		/* reconnect if no credits and no requests in flight */
 		if (zero_credits(server)) {
-			cifs_reconnect(server);
+			cifs_reconnect(server, false);
 			return -ECONNABORTED;
 		}
 
@@ -587,13 +625,18 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
 		else
 			length = sock_recvmsg(server->ssocket, smb_msg, 0);
 
-		if (server->tcpStatus == CifsExiting)
+		spin_lock(&cifs_tcp_ses_lock);
+		if (server->tcpStatus == CifsExiting) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			return -ESHUTDOWN;
+		}
 
 		if (server->tcpStatus == CifsNeedReconnect) {
-			cifs_reconnect(server);
+			spin_unlock(&cifs_tcp_ses_lock);
+			cifs_reconnect(server, false);
 			return -ECONNABORTED;
 		}
+		spin_unlock(&cifs_tcp_ses_lock);
 
 		if (length == -ERESTARTSYS ||
 		    length == -EAGAIN ||
@@ -610,7 +653,7 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
 
 		if (length <= 0) {
 			cifs_dbg(FYI, "Received no data or error: %d\n", length);
-			cifs_reconnect(server);
+			cifs_reconnect(server, false);
 			return -ECONNABORTED;
 		}
 	}
@@ -689,11 +732,11 @@ is_smb_response(struct TCP_Server_Info *server, unsigned char type)
 		 * initialize frame).
 		 */
 		cifs_set_port((struct sockaddr *)&server->dstaddr, CIFS_PORT);
-		cifs_reconnect(server);
+		cifs_reconnect(server, true);
 		break;
 	default:
 		cifs_server_dbg(VFS, "RFC 1002 unknown response type 0x%x\n", type);
-		cifs_reconnect(server);
+		cifs_reconnect(server, true);
 	}
 
 	return false;
@@ -771,9 +814,9 @@ static void clean_demultiplex_info(struct TCP_Server_Info *server)
 	cancel_delayed_work_sync(&server->echo);
 	cancel_delayed_work_sync(&server->resolve);
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	server->tcpStatus = CifsExiting;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 	wake_up_all(&server->response_q);
 
 	/* check if we have blocked requests that need to free */
@@ -866,7 +909,7 @@ standard_receive3(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 	if (pdu_length > CIFSMaxBufSize + MAX_HEADER_SIZE(server) -
 		server->vals->header_preamble_size) {
 		cifs_server_dbg(VFS, "SMB response too long (%u bytes)\n", pdu_length);
-		cifs_reconnect(server);
+		cifs_reconnect(server, true);
 		return -ECONNABORTED;
 	}
 
@@ -913,7 +956,7 @@ cifs_handle_standard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
 
 	if (server->ops->is_session_expired &&
 	    server->ops->is_session_expired(buf)) {
-		cifs_reconnect(server);
+		cifs_reconnect(server, true);
 		return -1;
 	}
 
@@ -1017,7 +1060,7 @@ next_pdu:
 		    server->vals->header_preamble_size) {
 			cifs_server_dbg(VFS, "SMB response too short (%u bytes)\n",
 				 server->pdu_size);
-			cifs_reconnect(server);
+			cifs_reconnect(server, true);
 			continue;
 		}
 
@@ -1069,7 +1112,7 @@ next_pdu:
 		    server->ops->is_status_io_timeout(buf)) {
 			num_io_timeout++;
 			if (num_io_timeout > NUM_STATUS_IO_TIMEOUT) {
-				cifs_reconnect(server);
+				cifs_reconnect(server, false);
 				num_io_timeout = 0;
 				continue;
 			}
@@ -1390,9 +1433,9 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
 	else
 		cancel_delayed_work_sync(&server->reconnect);
 
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&cifs_tcp_ses_lock);
 	server->tcpStatus = CifsExiting;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	cifs_crypto_secmech_release(server);
 
@@ -1545,7 +1588,9 @@ smbd_connected:
 	 * to the struct since the kernel thread not created yet
 	 * no need to spinlock this update of tcpStatus
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	tcp_ses->tcpStatus = CifsNeedNegotiate;
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	if ((ctx->max_credits < 20) || (ctx->max_credits > 60000))
 		tcp_ses->max_credits = SMB2_MAX_CREDITS_AVAILABLE;
@@ -1762,15 +1807,13 @@ void cifs_put_smb_ses(struct cifs_ses *ses)
 		spin_unlock(&cifs_tcp_ses_lock);
 		return;
 	}
-	spin_unlock(&cifs_tcp_ses_lock);
 
 	/* ses_count can never go negative */
 	WARN_ON(ses->ses_count < 0);
 
-	spin_lock(&GlobalMid_Lock);
 	if (ses->status == CifsGood)
 		ses->status = CifsExiting;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	cifs_free_ipc(ses);
 
@@ -1987,11 +2030,13 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
 		cifs_dbg(FYI, "Existing smb sess found (status=%d)\n",
 			 ses->status);
 
-		mutex_lock(&ses->session_mutex);
-		if (ses->need_reconnect) {
+		spin_lock(&ses->chan_lock);
+		if (cifs_chan_needs_reconnect(ses, server)) {
+			spin_unlock(&ses->chan_lock);
 			cifs_dbg(FYI, "Session needs reconnect\n");
 
-			rc = cifs_negotiate_protocol(xid, ses);
+			mutex_lock(&ses->session_mutex);
+			rc = cifs_negotiate_protocol(xid, ses, server);
 			if (rc) {
 				mutex_unlock(&ses->session_mutex);
 				/* problem -- put our ses reference */
@@ -2000,7 +2045,7 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
 				return ERR_PTR(rc);
 			}
 
-			rc = cifs_setup_session(xid, ses,
+			rc = cifs_setup_session(xid, ses, server,
 						ctx->local_nls);
 			if (rc) {
 				mutex_unlock(&ses->session_mutex);
@@ -2009,8 +2054,11 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
 				free_xid(xid);
 				return ERR_PTR(rc);
 			}
+			mutex_unlock(&ses->session_mutex);
+
+			spin_lock(&ses->chan_lock);
 		}
-		mutex_unlock(&ses->session_mutex);
+		spin_unlock(&ses->chan_lock);
 
 		/* existing SMB ses has a server reference already */
 		cifs_put_tcp_session(server, 0);
@@ -2060,28 +2108,33 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
 
 	ses->sectype = ctx->sectype;
 	ses->sign = ctx->sign;
-	mutex_lock(&ses->session_mutex);
 
 	/* add server as first channel */
 	spin_lock(&ses->chan_lock);
 	ses->chans[0].server = server;
 	ses->chan_count = 1;
 	ses->chan_max = ctx->multichannel ? ctx->max_channels:1;
+	ses->chans_need_reconnect = 1;
 	spin_unlock(&ses->chan_lock);
 
-	rc = cifs_negotiate_protocol(xid, ses);
+	mutex_lock(&ses->session_mutex);
+	rc = cifs_negotiate_protocol(xid, ses, server);
 	if (!rc)
-		rc = cifs_setup_session(xid, ses, ctx->local_nls);
+		rc = cifs_setup_session(xid, ses, server, ctx->local_nls);
+	mutex_unlock(&ses->session_mutex);
 
 	/* each channel uses a different signing key */
 	memcpy(ses->chans[0].signkey, ses->smb3signingkey,
 	       sizeof(ses->smb3signingkey));
 
-	mutex_unlock(&ses->session_mutex);
 	if (rc)
 		goto get_ses_fail;
 
-	/* success, put it on the list and add it as first channel */
+	/*
+	 * success, put it on the list and add it as first channel
+	 * note: the session becomes active soon after this. So you'll
+	 * need to lock before changing something in the session.
+	 */
 	spin_lock(&cifs_tcp_ses_lock);
 	list_add(&ses->smb_ses_list, &server->smb_ses_list);
 	spin_unlock(&cifs_tcp_ses_lock);
@@ -2161,6 +2214,9 @@ cifs_put_tcon(struct cifs_tcon *tcon)
 	/* tc_count can never go negative */
 	WARN_ON(tcon->tc_count < 0);
 
+	list_del_init(&tcon->tcon_list);
+	spin_unlock(&cifs_tcp_ses_lock);
+
 	if (tcon->use_witness) {
 		int rc;
 
@@ -2171,9 +2227,6 @@ cifs_put_tcon(struct cifs_tcon *tcon)
 		}
 	}
 
-	list_del_init(&tcon->tcon_list);
-	spin_unlock(&cifs_tcp_ses_lock);
-
 	xid = get_xid();
 	if (ses->server->ops->tree_disconnect)
 		ses->server->ops->tree_disconnect(xid, tcon);
@@ -2290,10 +2343,6 @@ cifs_get_tcon(struct cifs_ses *ses, struct smb3_fs_context *ctx)
 		}
 	}
 
-	/*
-	 * BB Do we need to wrap session_mutex around this TCon call and Unix
-	 * SetFS as we do on SessSetup and reconnect?
-	 */
 	xid = get_xid();
 	rc = ses->server->ops->tree_connect(xid, ses, ctx->UNC, tcon,
 					    ctx->local_nls);
@@ -3029,12 +3078,15 @@ static int mount_get_conns(struct mount_ctx *mnt_ctx)
 		 * for just this mount.
 		 */
 		reset_cifs_unix_caps(xid, tcon, cifs_sb, ctx);
+		spin_lock(&cifs_tcp_ses_lock);
 		if ((tcon->ses->server->tcpStatus == CifsNeedReconnect) &&
 		    (le64_to_cpu(tcon->fsUnixInfo.Capability) &
 		     CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP)) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			rc = -EACCES;
 			goto out;
 		}
+		spin_unlock(&cifs_tcp_ses_lock);
 	} else
 		tcon->unix_ext = 0; /* server does not support them */
 
@@ -3709,7 +3761,9 @@ CIFSTCon(const unsigned int xid, struct cifs_ses *ses,
 	if (rc == 0) {
 		bool is_unicode;
 
+		spin_lock(&cifs_tcp_ses_lock);
 		tcon->tidStatus = CifsGood;
+		spin_unlock(&cifs_tcp_ses_lock);
 		tcon->need_reconnect = false;
 		tcon->tid = smb_buffer_response->Tid;
 		bcc_ptr = pByteArea(smb_buffer_response);
@@ -3799,26 +3853,32 @@ cifs_umount(struct cifs_sb_info *cifs_sb)
 }
 
 int
-cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses)
+cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses,
+			struct TCP_Server_Info *server)
 {
 	int rc = 0;
-	struct TCP_Server_Info *server = cifs_ses_server(ses);
 
 	if (!server->ops->need_neg || !server->ops->negotiate)
 		return -ENOSYS;
 
 	/* only send once per connect */
-	if (!server->ops->need_neg(server))
+	spin_lock(&cifs_tcp_ses_lock);
+	if (!server->ops->need_neg(server) ||
+	    server->tcpStatus != CifsNeedNegotiate) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return 0;
+	}
+	server->tcpStatus = CifsInNegotiate;
+	spin_unlock(&cifs_tcp_ses_lock);
 
-	rc = server->ops->negotiate(xid, ses);
+	rc = server->ops->negotiate(xid, ses, server);
 	if (rc == 0) {
-		spin_lock(&GlobalMid_Lock);
-		if (server->tcpStatus == CifsNeedNegotiate)
-			server->tcpStatus = CifsGood;
+		spin_lock(&cifs_tcp_ses_lock);
+		if (server->tcpStatus == CifsInNegotiate)
+			server->tcpStatus = CifsNeedSessSetup;
 		else
 			rc = -EHOSTDOWN;
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&cifs_tcp_ses_lock);
 	}
 
 	return rc;
@@ -3826,12 +3886,26 @@ cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses)
 
 int
 cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
+		   struct TCP_Server_Info *server,
 		   struct nls_table *nls_info)
 {
 	int rc = -ENOSYS;
-	struct TCP_Server_Info *server = cifs_ses_server(ses);
+	bool is_binding = false;
 
-	if (!ses->binding) {
+	/* only send once per connect */
+	spin_lock(&cifs_tcp_ses_lock);
+	if (server->tcpStatus != CifsNeedSessSetup) {
+		spin_unlock(&cifs_tcp_ses_lock);
+		return 0;
+	}
+	ses->status = CifsInSessSetup;
+	spin_unlock(&cifs_tcp_ses_lock);
+
+	spin_lock(&ses->chan_lock);
+	is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);
+	spin_unlock(&ses->chan_lock);
+
+	if (!is_binding) {
 		ses->capabilities = server->capabilities;
 		if (!linuxExtEnabled)
 			ses->capabilities &= (~server->vals->cap_unix);
@@ -3849,7 +3923,7 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
 		 server->sec_mode, server->capabilities, server->timeAdj);
 
 	if (server->ops->sess_setup)
-		rc = server->ops->sess_setup(xid, ses, nls_info);
+		rc = server->ops->sess_setup(xid, ses, server, nls_info);
 
 	if (rc)
 		cifs_server_dbg(VFS, "Send error in SessSetup = %d\n", rc);
@@ -4197,6 +4271,17 @@ static int __tree_connect_dfs_target(const unsigned int xid, struct cifs_tcon *t
 	struct dfs_cache_tgt_iterator *tit;
 	bool target_match;
 
+	/* only send once per connect */
+	spin_lock(&cifs_tcp_ses_lock);
+	if (tcon->ses->status != CifsGood ||
+	    (tcon->tidStatus != CifsNew &&
+	    tcon->tidStatus != CifsNeedTcon)) {
+		spin_unlock(&cifs_tcp_ses_lock);
+		return 0;
+	}
+	tcon->tidStatus = CifsInTcon;
+	spin_unlock(&cifs_tcp_ses_lock);
+
 	extract_unc_hostname(server->hostname, &tcp_host, &tcp_host_len);
 
 	tit = dfs_cache_get_tgt_iterator(tl);
@@ -4355,6 +4440,17 @@ int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const stru
 {
 	const struct smb_version_operations *ops = tcon->ses->server->ops;
 
+	/* only send once per connect */
+	spin_lock(&cifs_tcp_ses_lock);
+	if (tcon->ses->status != CifsGood ||
+	    (tcon->tidStatus != CifsNew &&
+	    tcon->tidStatus != CifsNeedTcon)) {
+		spin_unlock(&cifs_tcp_ses_lock);
+		return 0;
+	}
+	tcon->tidStatus = CifsInTcon;
+	spin_unlock(&cifs_tcp_ses_lock);
+
 	return ops->tree_connect(xid, tcon->ses, tcon->treeName, tcon, nlsc);
 }
 #endif
diff --git a/fs/cifs/netmisc.c b/fs/cifs/netmisc.c
index fa9fbd6a819c..43b16b6d108c 100644
--- a/fs/cifs/netmisc.c
+++ b/fs/cifs/netmisc.c
@@ -896,10 +896,10 @@ map_and_check_smb_error(struct mid_q_entry *mid, bool logErr)
 		if (class == ERRSRV && code == ERRbaduid) {
 			cifs_dbg(FYI, "Server returned 0x%x, reconnecting session...\n",
 				code);
-			spin_lock(&GlobalMid_Lock);
+			spin_lock(&cifs_tcp_ses_lock);
 			if (mid->server->tcpStatus != CifsExiting)
 				mid->server->tcpStatus = CifsNeedReconnect;
-			spin_unlock(&GlobalMid_Lock);
+			spin_unlock(&cifs_tcp_ses_lock);
 		}
 	}
 
diff --git a/fs/cifs/ntlmssp.h b/fs/cifs/ntlmssp.h
index fe707f45da89..6d242af536cb 100644
--- a/fs/cifs/ntlmssp.h
+++ b/fs/cifs/ntlmssp.h
@@ -121,7 +121,9 @@ typedef struct _AUTHENTICATE_MESSAGE {
 int decode_ntlmssp_challenge(char *bcc_ptr, int blob_len, struct cifs_ses *ses);
 int build_ntlmssp_negotiate_blob(unsigned char **pbuffer, u16 *buflen,
 				 struct cifs_ses *ses,
+				 struct TCP_Server_Info *server,
 				 const struct nls_table *nls_cp);
 int build_ntlmssp_auth_blob(unsigned char **pbuffer, u16 *buflen,
 			struct cifs_ses *ses,
+			struct TCP_Server_Info *server,
 			const struct nls_table *nls_cp);
diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 035dc3e245dc..d12490e12be5 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -65,6 +65,53 @@ bool is_ses_using_iface(struct cifs_ses *ses, struct cifs_server_iface *iface)
 	return false;
 }
 
+unsigned int
+cifs_ses_get_chan_index(struct cifs_ses *ses,
+			struct TCP_Server_Info *server)
+{
+	unsigned int i;
+
+	for (i = 0; i < ses->chan_count; i++) {
+		if (ses->chans[i].server == server)
+			return i;
+	}
+
+	/* If we didn't find the channel, it is likely a bug */
+	WARN_ON(1);
+	return 0;
+}
+
+void
+cifs_chan_set_need_reconnect(struct cifs_ses *ses,
+			     struct TCP_Server_Info *server)
+{
+	unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
+
+	set_bit(chan_index, &ses->chans_need_reconnect);
+	cifs_dbg(FYI, "Set reconnect bitmask for chan %u; now 0x%lx\n",
+		 chan_index, ses->chans_need_reconnect);
+}
+
+void
+cifs_chan_clear_need_reconnect(struct cifs_ses *ses,
+			       struct TCP_Server_Info *server)
+{
+	unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
+
+	clear_bit(chan_index, &ses->chans_need_reconnect);
+	cifs_dbg(FYI, "Cleared reconnect bitmask for chan %u; now 0x%lx\n",
+		 chan_index, ses->chans_need_reconnect);
+}
+
+bool
+cifs_chan_needs_reconnect(struct cifs_ses *ses,
+			  struct TCP_Server_Info *server)
+{
+	unsigned int chan_index = cifs_ses_get_chan_index(ses, server);
+
+	return CIFS_CHAN_NEEDS_RECONNECT(ses, chan_index);
+}
+
 /* returns number of channels added */
 int cifs_try_adding_channels(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses)
 {
@@ -261,9 +308,8 @@ cifs_ses_add_channel(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
 
 	chan_server = cifs_get_tcp_session(&ctx, ses->server);
 
-	mutex_lock(&ses->session_mutex);
 	spin_lock(&ses->chan_lock);
-	chan = ses->binding_chan = &ses->chans[ses->chan_count];
+	chan = &ses->chans[ses->chan_count];
 	chan->server = chan_server;
 	if (IS_ERR(chan->server)) {
 		rc = PTR_ERR(chan->server);
@@ -271,8 +317,15 @@ cifs_ses_add_channel(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
 		spin_unlock(&ses->chan_lock);
 		goto out;
 	}
+	ses->chan_count++;
+	atomic_set(&ses->chan_seq, 0);
+
+	/* Mark this channel as needing connect/setup */
+	cifs_chan_set_need_reconnect(ses, chan->server);
+
 	spin_unlock(&ses->chan_lock);
 
+	mutex_lock(&ses->session_mutex);
 	/*
 	 * We need to allocate the server crypto now as we will need
 	 * to sign packets before we generate the channel signing key
@@ -281,37 +334,29 @@ cifs_ses_add_channel(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
 	rc = smb311_crypto_shash_allocate(chan->server);
 	if (rc) {
 		cifs_dbg(VFS, "%s: crypto alloc failed\n", __func__);
+		mutex_unlock(&ses->session_mutex);
 		goto out;
 	}
 
-	ses->binding = true;
-	rc = cifs_negotiate_protocol(xid, ses);
-	if (rc)
-		goto out;
-
-	rc = cifs_setup_session(xid, ses, cifs_sb->local_nls);
-	if (rc)
-		goto out;
-
-	/* success, put it on the list
-	 * XXX: sharing ses between 2 tcp servers is not possible, the
-	 * way "internal" linked lists works in linux makes element
-	 * only able to belong to one list
-	 *
-	 * the binding session is already established so the rest of
-	 * the code should be able to look it up, no need to add the
-	 * ses to the new server.
-	 */
+	rc = cifs_negotiate_protocol(xid, ses, chan->server);
+	if (!rc)
+		rc = cifs_setup_session(xid, ses, chan->server, cifs_sb->local_nls);
 
-	spin_lock(&ses->chan_lock);
-	ses->chan_count++;
-	atomic_set(&ses->chan_seq, 0);
-	spin_unlock(&ses->chan_lock);
+	mutex_unlock(&ses->session_mutex);
 
 out:
-	ses->binding = false;
-	ses->binding_chan = NULL;
-	mutex_unlock(&ses->session_mutex);
+	if (rc && chan->server) {
+		spin_lock(&ses->chan_lock);
+		/* we rely on all bits beyond chan_count to be clear */
+		cifs_chan_clear_need_reconnect(ses, chan->server);
+		ses->chan_count--;
+		/*
+		 * chan_count should never reach 0 as at least the primary
+		 * channel is always allocated
+		 */
+		WARN_ON(ses->chan_count < 1);
+		spin_unlock(&ses->chan_lock);
+	}
 
 	if (rc && chan->server)
 		cifs_put_tcp_session(chan->server, 0);
@@ -325,14 +370,16 @@ void cifs_ses_mark_for_reconnect(struct cifs_ses *ses)
 	int i;
 
 	for (i = 0; i < ses->chan_count; i++) {
-		spin_lock(&GlobalMid_Lock);
+		spin_lock(&cifs_tcp_ses_lock);
 		if (ses->chans[i].server->tcpStatus != CifsExiting)
 			ses->chans[i].server->tcpStatus = CifsNeedReconnect;
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&cifs_tcp_ses_lock);
 	}
 }
 
-static __u32 cifs_ssetup_hdr(struct cifs_ses *ses, SESSION_SETUP_ANDX *pSMB)
+static __u32 cifs_ssetup_hdr(struct cifs_ses *ses,
+			     struct TCP_Server_Info *server,
+			     SESSION_SETUP_ANDX *pSMB)
 {
 	__u32 capabilities = 0;
 
@@ -345,7 +392,7 @@ static __u32 cifs_ssetup_hdr(struct cifs_ses *ses, SESSION_SETUP_ANDX *pSMB)
 	pSMB->req.MaxBufferSize = cpu_to_le16(min_t(u32,
 					CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4,
 					USHRT_MAX));
-	pSMB->req.MaxMpxCount = cpu_to_le16(ses->server->maxReq);
+	pSMB->req.MaxMpxCount = cpu_to_le16(server->maxReq);
 	pSMB->req.VcNumber = cpu_to_le16(1);
 
 	/* Now no need to set SMBFLG_CASELESS or obsolete CANONICAL PATH */
@@ -356,7 +403,7 @@ static __u32 cifs_ssetup_hdr(struct cifs_ses *ses, SESSION_SETUP_ANDX *pSMB)
 	capabilities = CAP_LARGE_FILES | CAP_NT_SMBS | CAP_LEVEL_II_OPLOCKS |
 			CAP_LARGE_WRITE_X | CAP_LARGE_READ_X;
 
-	if (ses->server->sign)
+	if (server->sign)
 		pSMB->req.hdr.Flags2 |= SMBFLG2_SECURITY_SIGNATURE;
 
 	if (ses->capabilities & CAP_UNICODE) {
@@ -719,10 +766,10 @@ static inline void cifs_security_buffer_from_str(SECURITY_BUFFER *pbuf,
 int build_ntlmssp_negotiate_blob(unsigned char **pbuffer,
 				 u16 *buflen,
 				 struct cifs_ses *ses,
+				 struct TCP_Server_Info *server,
 				 const struct nls_table *nls_cp)
 {
 	int rc = 0;
-	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	NEGOTIATE_MESSAGE *sec_blob;
 	__u32 flags;
 	unsigned char *tmp;
@@ -776,6 +823,7 @@ setup_ntlm_neg_ret:
 int build_ntlmssp_auth_blob(unsigned char **pbuffer,
 					u16 *buflen,
 				   struct cifs_ses *ses,
+				   struct TCP_Server_Info *server,
 				   const struct nls_table *nls_cp)
 {
 	int rc;
@@ -912,6 +960,7 @@ cifs_select_sectype(struct TCP_Server_Info *server, enum securityEnum requested)
 struct sess_data {
 	unsigned int xid;
 	struct cifs_ses *ses;
+	struct TCP_Server_Info *server;
 	struct nls_table *nls_cp;
 	void (*func)(struct sess_data *);
 	int result;
@@ -978,30 +1027,36 @@ static int
 sess_establish_session(struct sess_data *sess_data)
 {
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 
-	mutex_lock(&ses->server->srv_mutex);
-	if (!ses->server->session_estab) {
-		if (ses->server->sign) {
-			ses->server->session_key.response =
+	mutex_lock(&server->srv_mutex);
+	if (!server->session_estab) {
+		if (server->sign) {
+			server->session_key.response =
 				kmemdup(ses->auth_key.response,
 				ses->auth_key.len, GFP_KERNEL);
-			if (!ses->server->session_key.response) {
-				mutex_unlock(&ses->server->srv_mutex);
+			if (!server->session_key.response) {
+				mutex_unlock(&server->srv_mutex);
 				return -ENOMEM;
 			}
-			ses->server->session_key.len =
+			server->session_key.len =
 						ses->auth_key.len;
 		}
-		ses->server->sequence_number = 0x2;
-		ses->server->session_estab = true;
+		server->sequence_number = 0x2;
+		server->session_estab = true;
 	}
-	mutex_unlock(&ses->server->srv_mutex);
+	mutex_unlock(&server->srv_mutex);
 
 	cifs_dbg(FYI, "CIFS session established successfully\n");
-	spin_lock(&GlobalMid_Lock);
+	spin_lock(&ses->chan_lock);
+	cifs_chan_clear_need_reconnect(ses, server);
+	spin_unlock(&ses->chan_lock);
+
+	/* Even if one channel is active, session is in good state */
+	spin_lock(&cifs_tcp_ses_lock);
+	server->tcpStatus = CifsGood;
 	ses->status = CifsGood;
-	ses->need_reconnect = false;
-	spin_unlock(&GlobalMid_Lock);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	return 0;
 }
@@ -1036,6 +1091,7 @@ sess_auth_ntlmv2(struct sess_data *sess_data)
 	SESSION_SETUP_ANDX *pSMB;
 	char *bcc_ptr;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	__u32 capabilities;
 	__u16 bytes_remaining;
 
@@ -1047,7 +1103,7 @@ sess_auth_ntlmv2(struct sess_data *sess_data)
 
 	pSMB = (SESSION_SETUP_ANDX *)sess_data->iov[0].iov_base;
 	bcc_ptr = sess_data->iov[2].iov_base;
-	capabilities = cifs_ssetup_hdr(ses, pSMB);
+	capabilities = cifs_ssetup_hdr(ses, server, pSMB);
 
 	pSMB->req_no_secext.Capabilities = cpu_to_le32(capabilities);
 
@@ -1145,6 +1201,7 @@ sess_auth_kerberos(struct sess_data *sess_data)
 	SESSION_SETUP_ANDX *pSMB;
 	char *bcc_ptr;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	__u32 capabilities;
 	__u16 bytes_remaining;
 	struct key *spnego_key = NULL;
@@ -1159,9 +1216,9 @@ sess_auth_kerberos(struct sess_data *sess_data)
 
 	pSMB = (SESSION_SETUP_ANDX *)sess_data->iov[0].iov_base;
 	bcc_ptr = sess_data->iov[2].iov_base;
-	capabilities = cifs_ssetup_hdr(ses, pSMB);
+	capabilities = cifs_ssetup_hdr(ses, server, pSMB);
 
-	spnego_key = cifs_get_spnego_key(ses);
+	spnego_key = cifs_get_spnego_key(ses, server);
 	if (IS_ERR(spnego_key)) {
 		rc = PTR_ERR(spnego_key);
 		spnego_key = NULL;
@@ -1285,12 +1342,13 @@ _sess_auth_rawntlmssp_assemble_req(struct sess_data *sess_data)
 {
 	SESSION_SETUP_ANDX *pSMB;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	__u32 capabilities;
 	char *bcc_ptr;
 
 	pSMB = (SESSION_SETUP_ANDX *)sess_data->iov[0].iov_base;
 
-	capabilities = cifs_ssetup_hdr(ses, pSMB);
+	capabilities = cifs_ssetup_hdr(ses, server, pSMB);
 	if ((pSMB->req.hdr.Flags2 & SMBFLG2_UNICODE) == 0) {
 		cifs_dbg(VFS, "NTLMSSP requires Unicode support\n");
 		return -ENOSYS;
@@ -1324,6 +1382,7 @@ sess_auth_rawntlmssp_negotiate(struct sess_data *sess_data)
 	struct smb_hdr *smb_buf;
 	SESSION_SETUP_ANDX *pSMB;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	__u16 bytes_remaining;
 	char *bcc_ptr;
 	unsigned char *ntlmsspblob = NULL;
@@ -1351,7 +1410,7 @@ sess_auth_rawntlmssp_negotiate(struct sess_data *sess_data)
 
 	/* Build security blob before we assemble the request */
 	rc = build_ntlmssp_negotiate_blob(&ntlmsspblob,
-				     &blob_len, ses,
+				     &blob_len, ses, server,
 				     sess_data->nls_cp);
 	if (rc)
 		goto out;
@@ -1426,6 +1485,7 @@ sess_auth_rawntlmssp_authenticate(struct sess_data *sess_data)
 	struct smb_hdr *smb_buf;
 	SESSION_SETUP_ANDX *pSMB;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	__u16 bytes_remaining;
 	char *bcc_ptr;
 	unsigned char *ntlmsspblob = NULL;
@@ -1442,7 +1502,8 @@ sess_auth_rawntlmssp_authenticate(struct sess_data *sess_data)
 	pSMB = (SESSION_SETUP_ANDX *)sess_data->iov[0].iov_base;
 	smb_buf = (struct smb_hdr *)pSMB;
 	rc = build_ntlmssp_auth_blob(&ntlmsspblob,
-					&blob_len, ses, sess_data->nls_cp);
+					&blob_len, ses, server,
+					sess_data->nls_cp);
 	if (rc)
 		goto out_free_ntlmsspblob;
 	sess_data->iov[1].iov_len = blob_len;
@@ -1526,11 +1587,13 @@ out:
 	sess_data->result = rc;
 }
 
-static int select_sec(struct cifs_ses *ses, struct sess_data *sess_data)
+static int select_sec(struct sess_data *sess_data)
 {
 	int type;
+	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 
-	type = cifs_select_sectype(ses->server, ses->sectype);
+	type = cifs_select_sectype(server, ses->sectype);
 	cifs_dbg(FYI, "sess setup type %d\n", type);
 	if (type == Unspecified) {
 		cifs_dbg(VFS, "Unable to select appropriate authentication method!\n");
@@ -1561,7 +1624,8 @@ static int select_sec(struct cifs_ses *ses, struct sess_data *sess_data)
 }
 
 int CIFS_SessSetup(const unsigned int xid, struct cifs_ses *ses,
-		    const struct nls_table *nls_cp)
+		   struct TCP_Server_Info *server,
+		   const struct nls_table *nls_cp)
 {
 	int rc = 0;
 	struct sess_data *sess_data;
@@ -1575,15 +1639,16 @@ int CIFS_SessSetup(const unsigned int xid, struct cifs_ses *ses,
 	if (!sess_data)
 		return -ENOMEM;
 
-	rc = select_sec(ses, sess_data);
-	if (rc)
-		goto out;
-
 	sess_data->xid = xid;
 	sess_data->ses = ses;
+	sess_data->server = server;
 	sess_data->buf0_type = CIFS_NO_BUFFER;
 	sess_data->nls_cp = (struct nls_table *) nls_cp;
 
+	rc = select_sec(sess_data);
+	if (rc)
+		goto out;
+
 	while (sess_data->func)
 		sess_data->func(sess_data);
 
diff --git a/fs/cifs/smb1ops.c b/fs/cifs/smb1ops.c
index 3b83839fc2c2..8272c91e15ef 100644
--- a/fs/cifs/smb1ops.c
+++ b/fs/cifs/smb1ops.c
@@ -7,6 +7,7 @@
 
 #include <linux/pagemap.h>
 #include <linux/vfs.h>
+#include <uapi/linux/magic.h>
 #include "cifsglob.h"
 #include "cifsproto.h"
 #include "cifs_debug.h"
@@ -163,7 +164,7 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 {
 	__u64 mid = 0;
 	__u16 last_mid, cur_mid;
-	bool collision;
+	bool collision, reconnect = false;
 
 	spin_lock(&GlobalMid_Lock);
 
@@ -215,7 +216,7 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 		 * an eventual reconnect to clean out the pending_mid_q.
 		 */
 		if (num_mids > 32768)
-			server->tcpStatus = CifsNeedReconnect;
+			reconnect = true;
 
 		if (!collision) {
 			mid = (__u64)cur_mid;
@@ -225,6 +226,13 @@ cifs_get_next_mid(struct TCP_Server_Info *server)
 		cur_mid++;
 	}
 	spin_unlock(&GlobalMid_Lock);
+
+	if (reconnect) {
+		spin_lock(&cifs_tcp_ses_lock);
+		server->tcpStatus = CifsNeedReconnect;
+		spin_unlock(&cifs_tcp_ses_lock);
+	}
+
 	return mid;
 }
 
@@ -414,14 +422,16 @@ cifs_need_neg(struct TCP_Server_Info *server)
 }
 
 static int
-cifs_negotiate(const unsigned int xid, struct cifs_ses *ses)
+cifs_negotiate(const unsigned int xid,
+	       struct cifs_ses *ses,
+	       struct TCP_Server_Info *server)
 {
 	int rc;
-	rc = CIFSSMBNegotiate(xid, ses);
+	rc = CIFSSMBNegotiate(xid, ses, server);
 	if (rc == -EAGAIN) {
 		/* retry only once on 1st time connection */
-		set_credits(ses->server, 1);
-		rc = CIFSSMBNegotiate(xid, ses);
+		set_credits(server, 1);
+		rc = CIFSSMBNegotiate(xid, ses, server);
 		if (rc == -EAGAIN)
 			rc = -EHOSTDOWN;
 	}
@@ -878,7 +888,7 @@ cifs_queryfs(const unsigned int xid, struct cifs_tcon *tcon,
 {
 	int rc = -EOPNOTSUPP;
 
-	buf->f_type = CIFS_MAGIC_NUMBER;
+	buf->f_type = CIFS_SUPER_MAGIC;
 
 	/*
 	 * We could add a second check for a QFS Unix capability bit
diff --git a/fs/cifs/smb2glob.h b/fs/cifs/smb2glob.h
index ca692b2283cd..4125fd113cfb 100644
--- a/fs/cifs/smb2glob.h
+++ b/fs/cifs/smb2glob.h
@@ -13,8 +13,6 @@
 #ifndef _SMB2_GLOB_H
 #define _SMB2_GLOB_H
 
-#define SMB2_MAGIC_NUMBER 0xFE534D42
-
 /*
  *****************************************************************
  * Constants go here
diff --git a/fs/cifs/smb2misc.c b/fs/cifs/smb2misc.c
index cdcdef32759e..b25623e3fe3d 100644
--- a/fs/cifs/smb2misc.c
+++ b/fs/cifs/smb2misc.c
@@ -847,16 +847,17 @@ smb2_handle_cancelled_mid(struct mid_q_entry *mid, struct TCP_Server_Info *serve
  * SMB2 header.
  *
  * @ses:	server session structure
+ * @server:	pointer to server info
  * @iov:	array containing the SMB request we will send to the server
  * @nvec:	number of array entries for the iov
  */
 int
-smb311_update_preauth_hash(struct cifs_ses *ses, struct kvec *iov, int nvec)
+smb311_update_preauth_hash(struct cifs_ses *ses, struct TCP_Server_Info *server,
+			   struct kvec *iov, int nvec)
 {
 	int i, rc;
 	struct sdesc *d;
 	struct smb2_hdr *hdr;
-	struct TCP_Server_Info *server = cifs_ses_server(ses);
 
 	hdr = (struct smb2_hdr *)iov[0].iov_base;
 	/* neg prot are always taken */
diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index c5b1dea54ebc..af5d0830bc8a 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -13,6 +13,7 @@
 #include <linux/sort.h>
 #include <crypto/aead.h>
 #include <linux/fiemap.h>
+#include <uapi/linux/magic.h>
 #include "cifsfs.h"
 #include "cifsglob.h"
 #include "smb2pdu.h"
@@ -121,9 +122,13 @@ smb2_add_credits(struct TCP_Server_Info *server,
 			 optype, scredits, add);
 	}
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedReconnect
-	    || server->tcpStatus == CifsExiting)
+	    || server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	switch (rc) {
 	case -1:
@@ -208,11 +213,15 @@ smb2_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
 				return rc;
 			spin_lock(&server->req_lock);
 		} else {
+			spin_unlock(&server->req_lock);
+			spin_lock(&cifs_tcp_ses_lock);
 			if (server->tcpStatus == CifsExiting) {
-				spin_unlock(&server->req_lock);
+				spin_unlock(&cifs_tcp_ses_lock);
 				return -ENOENT;
 			}
+			spin_unlock(&cifs_tcp_ses_lock);
 
+			spin_lock(&server->req_lock);
 			scredits = server->credits;
 			/* can deadlock with reopen */
 			if (scredits <= 8) {
@@ -384,14 +393,16 @@ smb2_need_neg(struct TCP_Server_Info *server)
 }
 
 static int
-smb2_negotiate(const unsigned int xid, struct cifs_ses *ses)
+smb2_negotiate(const unsigned int xid,
+	       struct cifs_ses *ses,
+	       struct TCP_Server_Info *server)
 {
 	int rc;
 
 	spin_lock(&GlobalMid_Lock);
-	cifs_ses_server(ses)->CurrentMid = 0;
+	server->CurrentMid = 0;
 	spin_unlock(&GlobalMid_Lock);
-	rc = SMB2_negotiate(xid, ses);
+	rc = SMB2_negotiate(xid, ses, server);
 	/* BB we probably don't need to retry with modern servers */
 	if (rc == -EAGAIN)
 		rc = -EHOSTDOWN;
@@ -2747,7 +2758,7 @@ smb2_queryfs(const unsigned int xid, struct cifs_tcon *tcon,
 		goto qfs_exit;
 
 	rsp = (struct smb2_query_info_rsp *)rsp_iov.iov_base;
-	buf->f_type = SMB2_MAGIC_NUMBER;
+	buf->f_type = SMB2_SUPER_MAGIC;
 	info = (struct smb2_fs_full_size_info *)(
 		le16_to_cpu(rsp->OutputBufferOffset) + (char *)rsp);
 	rc = smb2_validate_iov(le16_to_cpu(rsp->OutputBufferOffset),
@@ -2789,7 +2800,7 @@ smb311_queryfs(const unsigned int xid, struct cifs_tcon *tcon,
 
 	rc = SMB311_posix_qfs_info(xid, tcon, fid.persistent_fid,
 				   fid.volatile_fid, buf);
-	buf->f_type = SMB2_MAGIC_NUMBER;
+	buf->f_type = SMB2_SUPER_MAGIC;
 	SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
 	return rc;
 }
@@ -4808,7 +4819,7 @@ handle_read_data(struct TCP_Server_Info *server, struct mid_q_entry *mid,
 	if (server->ops->is_session_expired &&
 	    server->ops->is_session_expired(buf)) {
 		if (!is_offloaded)
-			cifs_reconnect(server);
+			cifs_reconnect(server, true);
 		return -1;
 	}
 
@@ -4981,10 +4992,12 @@ static void smb2_decrypt_offload(struct work_struct *work)
 
 			mid->callback(mid);
 		} else {
+			spin_lock(&cifs_tcp_ses_lock);
 			spin_lock(&GlobalMid_Lock);
 			if (dw->server->tcpStatus == CifsNeedReconnect) {
 				mid->mid_state = MID_RETRY_NEEDED;
 				spin_unlock(&GlobalMid_Lock);
+				spin_unlock(&cifs_tcp_ses_lock);
 				mid->callback(mid);
 			} else {
 				mid->mid_state = MID_REQUEST_SUBMITTED;
@@ -4992,6 +5005,7 @@ static void smb2_decrypt_offload(struct work_struct *work)
 				list_add_tail(&mid->qhead,
 					&dw->server->pending_mid_q);
 				spin_unlock(&GlobalMid_Lock);
+				spin_unlock(&cifs_tcp_ses_lock);
 			}
 		}
 		cifs_mid_q_entry_release(mid);
@@ -5221,13 +5235,13 @@ smb3_receive_transform(struct TCP_Server_Info *server,
 						sizeof(struct smb2_hdr)) {
 		cifs_server_dbg(VFS, "Transform message is too small (%u)\n",
 			 pdu_length);
-		cifs_reconnect(server);
+		cifs_reconnect(server, true);
 		return -ECONNABORTED;
 	}
 
 	if (pdu_length < orig_len + sizeof(struct smb2_transform_hdr)) {
 		cifs_server_dbg(VFS, "Transform message is broken\n");
-		cifs_reconnect(server);
+		cifs_reconnect(server, true);
 		return -ECONNABORTED;
 	}
 
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 8b3670388cda..8d471df69c59 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -162,6 +162,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	if (smb2_command == SMB2_TREE_CONNECT || smb2_command == SMB2_IOCTL)
 		return 0;
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (tcon->tidStatus == CifsExiting) {
 		/*
 		 * only tree disconnect, open, and write,
@@ -171,11 +172,13 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		if ((smb2_command != SMB2_WRITE) &&
 		   (smb2_command != SMB2_CREATE) &&
 		   (smb2_command != SMB2_TREE_DISCONNECT)) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			cifs_dbg(FYI, "can not send cmd %d while umounting\n",
 				 smb2_command);
 			return -ENODEV;
 		}
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 	if ((!tcon->ses) || (tcon->ses->status == CifsExiting) ||
 	    (!tcon->ses->server) || !server)
 		return -EIO;
@@ -214,8 +217,12 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		}
 
 		/* are we still trying to reconnect? */
-		if (server->tcpStatus != CifsNeedReconnect)
+		spin_lock(&cifs_tcp_ses_lock);
+		if (server->tcpStatus != CifsNeedReconnect) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			break;
+		}
+		spin_unlock(&cifs_tcp_ses_lock);
 
 		if (retries && --retries)
 			continue;
@@ -232,64 +239,70 @@ 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();
 
 	/*
-	 * need to prevent multiple threads trying to simultaneously reconnect
-	 * the same SMB session
-	 */
-	mutex_lock(&tcon->ses->session_mutex);
-
-	/*
 	 * Recheck after acquire mutex. If another thread is negotiating
 	 * and the server never sends an answer the socket will be closed
 	 * and tcpStatus set to reconnect.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedReconnect) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		rc = -EHOSTDOWN;
-		mutex_unlock(&tcon->ses->session_mutex);
 		goto out;
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	/*
-	 * If we are reconnecting an extra channel, bind
+	 * need to prevent multiple threads trying to simultaneously
+	 * reconnect the same SMB session
 	 */
-	if (CIFS_SERVER_IS_CHAN(server)) {
-		ses->binding = true;
-		ses->binding_chan = cifs_ses_find_chan(ses, server);
+	spin_lock(&ses->chan_lock);
+	if (!cifs_chan_needs_reconnect(ses, server)) {
+		spin_unlock(&ses->chan_lock);
+
+		/* this means that we only need to tree connect */
+		if (tcon->need_reconnect)
+			goto skip_sess_setup;
+
+		goto out;
 	}
+	spin_unlock(&ses->chan_lock);
 
-	rc = cifs_negotiate_protocol(0, tcon->ses);
-	if (!rc && tcon->ses->need_reconnect) {
-		rc = cifs_setup_session(0, tcon->ses, nls_codepage);
+	mutex_lock(&ses->session_mutex);
+	rc = cifs_negotiate_protocol(0, ses, server);
+	if (!rc) {
+		rc = cifs_setup_session(0, ses, server, nls_codepage);
 		if ((rc == -EACCES) && !tcon->retry) {
+			mutex_unlock(&ses->session_mutex);
 			rc = -EHOSTDOWN;
-			ses->binding = false;
-			ses->binding_chan = NULL;
-			mutex_unlock(&tcon->ses->session_mutex);
 			goto failed;
 		}
 	}
-	/*
-	 * End of channel binding
-	 */
-	ses->binding = false;
-	ses->binding_chan = NULL;
 
 	if (rc || !tcon->need_reconnect) {
-		mutex_unlock(&tcon->ses->session_mutex);
+		mutex_unlock(&ses->session_mutex);
 		goto out;
 	}
 
+skip_sess_setup:
 	cifs_mark_open_files_invalid(tcon);
 	if (tcon->use_persistent)
 		tcon->need_reopen_files = true;
 
 	rc = cifs_tree_connect(0, tcon, nls_codepage);
-	mutex_unlock(&tcon->ses->session_mutex);
+	mutex_unlock(&ses->session_mutex);
 
 	cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc);
 	if (rc) {
@@ -833,7 +846,9 @@ add_posix_context(struct kvec *iov, unsigned int *num_iovec, umode_t mode)
  */
 
 int
-SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
+SMB2_negotiate(const unsigned int xid,
+	       struct cifs_ses *ses,
+	       struct TCP_Server_Info *server)
 {
 	struct smb_rqst rqst;
 	struct smb2_negotiate_req *req;
@@ -842,7 +857,6 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 	struct kvec rsp_iov;
 	int rc = 0;
 	int resp_buftype;
-	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	int blob_offset, blob_length;
 	char *security_blob;
 	int flags = CIFS_NEG_OP;
@@ -1221,6 +1235,7 @@ smb2_select_sectype(struct TCP_Server_Info *server, enum securityEnum requested)
 struct SMB2_sess_data {
 	unsigned int xid;
 	struct cifs_ses *ses;
+	struct TCP_Server_Info *server;
 	struct nls_table *nls_cp;
 	void (*func)(struct SMB2_sess_data *);
 	int result;
@@ -1242,9 +1257,10 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
 {
 	int rc;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	struct smb2_sess_setup_req *req;
-	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	unsigned int total_len;
+	bool is_binding = false;
 
 	rc = smb2_plain_req_init(SMB2_SESSION_SETUP, NULL, server,
 				 (void **) &req,
@@ -1252,11 +1268,16 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
 	if (rc)
 		return rc;
 
-	if (sess_data->ses->binding) {
-		req->hdr.SessionId = cpu_to_le64(sess_data->ses->Suid);
+	spin_lock(&ses->chan_lock);
+	is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);
+	spin_unlock(&ses->chan_lock);
+
+	if (is_binding) {
+		req->hdr.SessionId = cpu_to_le64(ses->Suid);
 		req->hdr.Flags |= SMB2_FLAGS_SIGNED;
 		req->PreviousSessionId = 0;
 		req->Flags = SMB2_SESSION_REQ_FLAG_BINDING;
+		cifs_dbg(FYI, "Binding to sess id: %llx\n", ses->Suid);
 	} else {
 		/* First session, not a reauthenticate */
 		req->hdr.SessionId = 0;
@@ -1266,6 +1287,8 @@ SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
 		 */
 		req->PreviousSessionId = cpu_to_le64(sess_data->previous_session);
 		req->Flags = 0; /* MBZ */
+		cifs_dbg(FYI, "Fresh session. Previous: %llx\n",
+			 sess_data->previous_session);
 	}
 
 	/* enough to enable echos and oplocks and one max size write */
@@ -1325,7 +1348,7 @@ SMB2_sess_sendreceive(struct SMB2_sess_data *sess_data)
 
 	/* BB add code to build os and lm fields */
 	rc = cifs_send_recv(sess_data->xid, sess_data->ses,
-			    cifs_ses_server(sess_data->ses),
+			    sess_data->server,
 			    &rqst,
 			    &sess_data->buf0_type,
 			    CIFS_LOG_ERROR | CIFS_SESS_OP, &rsp_iov);
@@ -1340,11 +1363,11 @@ SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
 {
 	int rc = 0;
 	struct cifs_ses *ses = sess_data->ses;
-	struct TCP_Server_Info *server = cifs_ses_server(ses);
+	struct TCP_Server_Info *server = sess_data->server;
 
 	mutex_lock(&server->srv_mutex);
 	if (server->ops->generate_signingkey) {
-		rc = server->ops->generate_signingkey(ses);
+		rc = server->ops->generate_signingkey(ses, server);
 		if (rc) {
 			cifs_dbg(FYI,
 				"SMB3 session key generation failed\n");
@@ -1359,13 +1382,16 @@ SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
 	mutex_unlock(&server->srv_mutex);
 
 	cifs_dbg(FYI, "SMB2/3 session established successfully\n");
-	/* keep existing ses state if binding */
-	if (!ses->binding) {
-		spin_lock(&GlobalMid_Lock);
-		ses->status = CifsGood;
-		ses->need_reconnect = false;
-		spin_unlock(&GlobalMid_Lock);
-	}
+
+	spin_lock(&ses->chan_lock);
+	cifs_chan_clear_need_reconnect(ses, server);
+	spin_unlock(&ses->chan_lock);
+
+	/* Even if one channel is active, session is in good state */
+	spin_lock(&cifs_tcp_ses_lock);
+	server->tcpStatus = CifsGood;
+	ses->status = CifsGood;
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	return rc;
 }
@@ -1376,15 +1402,17 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
 {
 	int rc;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	struct cifs_spnego_msg *msg;
 	struct key *spnego_key = NULL;
 	struct smb2_sess_setup_rsp *rsp = NULL;
+	bool is_binding = false;
 
 	rc = SMB2_sess_alloc_buffer(sess_data);
 	if (rc)
 		goto out;
 
-	spnego_key = cifs_get_spnego_key(ses);
+	spnego_key = cifs_get_spnego_key(ses, server);
 	if (IS_ERR(spnego_key)) {
 		rc = PTR_ERR(spnego_key);
 		if (rc == -ENOKEY)
@@ -1405,8 +1433,12 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
 		goto out_put_spnego_key;
 	}
 
+	spin_lock(&ses->chan_lock);
+	is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);
+	spin_unlock(&ses->chan_lock);
+
 	/* keep session key if binding */
-	if (!ses->binding) {
+	if (!is_binding) {
 		ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
 						 GFP_KERNEL);
 		if (!ses->auth_key.response) {
@@ -1427,7 +1459,7 @@ SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
 
 	rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;
 	/* keep session id and flags if binding */
-	if (!ses->binding) {
+	if (!is_binding) {
 		ses->Suid = le64_to_cpu(rsp->hdr.SessionId);
 		ses->session_flags = le16_to_cpu(rsp->SessionFlags);
 	}
@@ -1459,10 +1491,12 @@ SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data)
 {
 	int rc;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	struct smb2_sess_setup_rsp *rsp = NULL;
 	unsigned char *ntlmssp_blob = NULL;
 	bool use_spnego = false; /* else use raw ntlmssp */
 	u16 blob_length = 0;
+	bool is_binding = false;
 
 	/*
 	 * If memory allocation is successful, caller of this function
@@ -1480,7 +1514,7 @@ SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data)
 		goto out_err;
 
 	rc = build_ntlmssp_negotiate_blob(&ntlmssp_blob,
-					  &blob_length, ses,
+					  &blob_length, ses, server,
 					  sess_data->nls_cp);
 	if (rc)
 		goto out_err;
@@ -1519,8 +1553,12 @@ SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data)
 
 	cifs_dbg(FYI, "rawntlmssp session setup challenge phase\n");
 
+	spin_lock(&ses->chan_lock);
+	is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);
+	spin_unlock(&ses->chan_lock);
+
 	/* keep existing ses id and flags if binding */
-	if (!ses->binding) {
+	if (!is_binding) {
 		ses->Suid = le64_to_cpu(rsp->hdr.SessionId);
 		ses->session_flags = le16_to_cpu(rsp->SessionFlags);
 	}
@@ -1545,11 +1583,13 @@ SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data)
 {
 	int rc;
 	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 	struct smb2_sess_setup_req *req;
 	struct smb2_sess_setup_rsp *rsp = NULL;
 	unsigned char *ntlmssp_blob = NULL;
 	bool use_spnego = false; /* else use raw ntlmssp */
 	u16 blob_length = 0;
+	bool is_binding = false;
 
 	rc = SMB2_sess_alloc_buffer(sess_data);
 	if (rc)
@@ -1558,8 +1598,9 @@ SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data)
 	req = (struct smb2_sess_setup_req *) sess_data->iov[0].iov_base;
 	req->hdr.SessionId = cpu_to_le64(ses->Suid);
 
-	rc = build_ntlmssp_auth_blob(&ntlmssp_blob, &blob_length, ses,
-					sess_data->nls_cp);
+	rc = build_ntlmssp_auth_blob(&ntlmssp_blob, &blob_length,
+				     ses, server,
+				     sess_data->nls_cp);
 	if (rc) {
 		cifs_dbg(FYI, "build_ntlmssp_auth_blob failed %d\n", rc);
 		goto out;
@@ -1580,8 +1621,12 @@ SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data)
 
 	rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;
 
+	spin_lock(&ses->chan_lock);
+	is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);
+	spin_unlock(&ses->chan_lock);
+
 	/* keep existing ses id and flags if binding */
-	if (!ses->binding) {
+	if (!is_binding) {
 		ses->Suid = le64_to_cpu(rsp->hdr.SessionId);
 		ses->session_flags = le16_to_cpu(rsp->SessionFlags);
 	}
@@ -1612,11 +1657,13 @@ out:
 }
 
 static int
-SMB2_select_sec(struct cifs_ses *ses, struct SMB2_sess_data *sess_data)
+SMB2_select_sec(struct SMB2_sess_data *sess_data)
 {
 	int type;
+	struct cifs_ses *ses = sess_data->ses;
+	struct TCP_Server_Info *server = sess_data->server;
 
-	type = smb2_select_sectype(cifs_ses_server(ses), ses->sectype);
+	type = smb2_select_sectype(server, ses->sectype);
 	cifs_dbg(FYI, "sess setup type %d\n", type);
 	if (type == Unspecified) {
 		cifs_dbg(VFS, "Unable to select appropriate authentication method!\n");
@@ -1640,10 +1687,10 @@ SMB2_select_sec(struct cifs_ses *ses, struct SMB2_sess_data *sess_data)
 
 int
 SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
+		struct TCP_Server_Info *server,
 		const struct nls_table *nls_cp)
 {
 	int rc = 0;
-	struct TCP_Server_Info *server = cifs_ses_server(ses);
 	struct SMB2_sess_data *sess_data;
 
 	cifs_dbg(FYI, "Session Setup\n");
@@ -1657,15 +1704,17 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
 	if (!sess_data)
 		return -ENOMEM;
 
-	rc = SMB2_select_sec(ses, sess_data);
-	if (rc)
-		goto out;
 	sess_data->xid = xid;
 	sess_data->ses = ses;
+	sess_data->server = server;
 	sess_data->buf0_type = CIFS_NO_BUFFER;
 	sess_data->nls_cp = (struct nls_table *) nls_cp;
 	sess_data->previous_session = ses->Suid;
 
+	rc = SMB2_select_sec(sess_data);
+	if (rc)
+		goto out;
+
 	/*
 	 * Initialize the session hash with the server one.
 	 */
@@ -1704,8 +1753,12 @@ 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);
@@ -1867,7 +1920,9 @@ SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
 	tcon->share_flags = le32_to_cpu(rsp->ShareFlags);
 	tcon->capabilities = rsp->Capabilities; /* we keep caps little endian */
 	tcon->maximal_access = le32_to_cpu(rsp->MaximalAccess);
+	spin_lock(&cifs_tcp_ses_lock);
 	tcon->tidStatus = CifsGood;
+	spin_unlock(&cifs_tcp_ses_lock);
 	tcon->need_reconnect = false;
 	tcon->tid = le32_to_cpu(rsp->hdr.Id.SyncId.TreeId);
 	strlcpy(tcon->treeName, tree, sizeof(tcon->treeName));
@@ -1913,8 +1968,13 @@ 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);
 
@@ -3797,13 +3857,16 @@ SMB2_echo(struct TCP_Server_Info *server)
 				 .rq_nvec = 1 };
 	unsigned int total_len;
 
-	cifs_dbg(FYI, "In echo request\n");
+	cifs_dbg(FYI, "In echo request for conn_id %lld\n", server->conn_id);
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedNegotiate) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		/* No need to send echo on newly established connections */
 		mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
 		return rc;
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	rc = smb2_plain_req_init(SMB2_ECHO, NULL, server,
 				 (void **)&req, &total_len);
diff --git a/fs/cifs/smb2proto.h b/fs/cifs/smb2proto.h
index 096fada16ebd..4a7062fd1c26 100644
--- a/fs/cifs/smb2proto.h
+++ b/fs/cifs/smb2proto.h
@@ -123,8 +123,11 @@ extern void smb2_set_related(struct smb_rqst *rqst);
  * SMB2 Worker functions - most of protocol specific implementation details
  * are contained within these calls.
  */
-extern int SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses);
+extern int SMB2_negotiate(const unsigned int xid,
+			  struct cifs_ses *ses,
+			  struct TCP_Server_Info *server);
 extern int SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
+			   struct TCP_Server_Info *server,
 			   const struct nls_table *nls_cp);
 extern int SMB2_logoff(const unsigned int xid, struct cifs_ses *ses);
 extern int SMB2_tcon(const unsigned int xid, struct cifs_ses *ses,
@@ -276,6 +279,7 @@ extern void smb2_copy_fs_info_to_kstatfs(
 	 struct kstatfs *kst);
 extern int smb311_crypto_shash_allocate(struct TCP_Server_Info *server);
 extern int smb311_update_preauth_hash(struct cifs_ses *ses,
+				      struct TCP_Server_Info *server,
 				      struct kvec *iov, int nvec);
 extern int smb2_query_info_compound(const unsigned int xid,
 				    struct cifs_tcon *tcon,
diff --git a/fs/cifs/smb2transport.c b/fs/cifs/smb2transport.c
index 2bf047b390a9..b70a49b4edc0 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
@@ -624,8 +634,12 @@ smb2_sign_rqst(struct smb_rqst *rqst, struct TCP_Server_Info *server)
 
 	if (!is_signed)
 		return 0;
-	if (server->tcpStatus == CifsNeedNegotiate)
+	spin_lock(&cifs_tcp_ses_lock);
+	if (server->tcpStatus == CifsNeedNegotiate) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return 0;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 	if (!is_binding && !server->session_estab) {
 		strncpy(shdr->Signature, "BSRSPYL", 8);
 		return 0;
@@ -741,30 +755,41 @@ static int
 smb2_get_mid_entry(struct cifs_ses *ses, struct TCP_Server_Info *server,
 		   struct smb2_hdr *shdr, struct mid_q_entry **mid)
 {
-	if (server->tcpStatus == CifsExiting)
+	spin_lock(&cifs_tcp_ses_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -ENOENT;
+	}
 
 	if (server->tcpStatus == CifsNeedReconnect) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
 		return -EAGAIN;
 	}
 
 	if (server->tcpStatus == CifsNeedNegotiate &&
-	   shdr->Command != SMB2_NEGOTIATE)
+	   shdr->Command != SMB2_NEGOTIATE) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -EAGAIN;
+	}
 
 	if (ses->status == CifsNew) {
 		if ((shdr->Command != SMB2_SESSION_SETUP) &&
-		    (shdr->Command != SMB2_NEGOTIATE))
+		    (shdr->Command != SMB2_NEGOTIATE)) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			return -EAGAIN;
+		}
 		/* else ok - we are setting up session */
 	}
 
 	if (ses->status == CifsExiting) {
-		if (shdr->Command != SMB2_LOGOFF)
+		if (shdr->Command != SMB2_LOGOFF) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			return -EAGAIN;
+		}
 		/* else ok - we are shutting down the session */
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	*mid = smb2_mid_entry_alloc(shdr, server);
 	if (*mid == NULL)
@@ -837,9 +862,13 @@ smb2_setup_async_request(struct TCP_Server_Info *server, struct smb_rqst *rqst)
 			(struct smb2_hdr *)rqst->rq_iov[0].iov_base;
 	struct mid_q_entry *mid;
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedNegotiate &&
-	   shdr->Command != SMB2_NEGOTIATE)
+	   shdr->Command != SMB2_NEGOTIATE) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return ERR_PTR(-EAGAIN);
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	smb2_seq_num_into_buf(server, shdr);
 
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 61ea3d3f95b4..93f0e8c1ea23 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -430,9 +430,9 @@ unmask:
 		 * be taken as the remainder of this one. We need to kill the
 		 * socket so the server throws away the partial SMB
 		 */
-		spin_lock(&GlobalMid_Lock);
+		spin_lock(&cifs_tcp_ses_lock);
 		server->tcpStatus = CifsNeedReconnect;
-		spin_unlock(&GlobalMid_Lock);
+		spin_unlock(&cifs_tcp_ses_lock);
 		trace_smb3_partial_send_reconnect(server->CurrentMid,
 						  server->conn_id, server->hostname);
 	}
@@ -578,10 +578,14 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
 				return -ERESTARTSYS;
 			spin_lock(&server->req_lock);
 		} else {
+			spin_unlock(&server->req_lock);
+
+			spin_lock(&cifs_tcp_ses_lock);
 			if (server->tcpStatus == CifsExiting) {
-				spin_unlock(&server->req_lock);
+				spin_unlock(&cifs_tcp_ses_lock);
 				return -ENOENT;
 			}
+			spin_unlock(&cifs_tcp_ses_lock);
 
 			/*
 			 * For normal commands, reserve the last MAX_COMPOUND
@@ -596,6 +600,7 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
 			 * for servers that are slow to hand out credits on
 			 * new sessions.
 			 */
+			spin_lock(&server->req_lock);
 			if (!optype && num_credits == 1 &&
 			    server->in_flight > 2 * MAX_COMPOUND &&
 			    *credits <= MAX_COMPOUND) {
@@ -723,28 +728,36 @@ cifs_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
 static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
 			struct mid_q_entry **ppmidQ)
 {
+	spin_lock(&cifs_tcp_ses_lock);
 	if (ses->server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -ENOENT;
 	}
 
 	if (ses->server->tcpStatus == CifsNeedReconnect) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
 		return -EAGAIN;
 	}
 
 	if (ses->status == CifsNew) {
 		if ((in_buf->Command != SMB_COM_SESSION_SETUP_ANDX) &&
-			(in_buf->Command != SMB_COM_NEGOTIATE))
+			(in_buf->Command != SMB_COM_NEGOTIATE)) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			return -EAGAIN;
+		}
 		/* else ok - we are setting up session */
 	}
 
 	if (ses->status == CifsExiting) {
 		/* check if SMB session is bad because we are setting it up */
-		if (in_buf->Command != SMB_COM_LOGOFF_ANDX)
+		if (in_buf->Command != SMB_COM_LOGOFF_ANDX) {
+			spin_unlock(&cifs_tcp_ses_lock);
 			return -EAGAIN;
+		}
 		/* else ok - we are shutting down session */
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	*ppmidQ = AllocMidQEntry(in_buf, ses->server);
 	if (*ppmidQ == NULL)
@@ -1044,19 +1057,11 @@ struct TCP_Server_Info *cifs_pick_channel(struct cifs_ses *ses)
 	if (!ses)
 		return NULL;
 
-	spin_lock(&ses->chan_lock);
-	if (!ses->binding) {
-		/* round robin */
-		if (ses->chan_count > 1) {
-			index = (uint)atomic_inc_return(&ses->chan_seq);
-			index %= ses->chan_count;
-		}
-		spin_unlock(&ses->chan_lock);
-		return ses->chans[index].server;
-	} else {
-		spin_unlock(&ses->chan_lock);
-		return cifs_ses_server(ses);
-	}
+	/* round robin */
+	index = (uint)atomic_inc_return(&ses->chan_seq);
+	index %= ses->chan_count;
+
+	return ses->chans[index].server;
 }
 
 int
@@ -1084,8 +1089,12 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 		return -EIO;
 	}
 
-	if (server->tcpStatus == CifsExiting)
+	spin_lock(&cifs_tcp_ses_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -ENOENT;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	/*
 	 * Wait for all the requests to become available.
@@ -1188,12 +1197,17 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 	/*
 	 * Compounding is never used during session establish.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if ((ses->status == CifsNew) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
+		spin_unlock(&cifs_tcp_ses_lock);
+
 		mutex_lock(&server->srv_mutex);
-		smb311_update_preauth_hash(ses, rqst[0].rq_iov,
-					   rqst[0].rq_nvec);
+		smb311_update_preauth_hash(ses, server, rqst[0].rq_iov, rqst[0].rq_nvec);
 		mutex_unlock(&server->srv_mutex);
+
+		spin_lock(&cifs_tcp_ses_lock);
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	for (i = 0; i < num_rqst; i++) {
 		rc = wait_for_response(server, midQ[i]);
@@ -1256,15 +1270,19 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
 	/*
 	 * Compounding is never used during session establish.
 	 */
+	spin_lock(&cifs_tcp_ses_lock);
 	if ((ses->status == CifsNew) || (optype & CIFS_NEG_OP) || (optype & CIFS_SESS_OP)) {
 		struct kvec iov = {
 			.iov_base = resp_iov[0].iov_base,
 			.iov_len = resp_iov[0].iov_len
 		};
+		spin_unlock(&cifs_tcp_ses_lock);
 		mutex_lock(&server->srv_mutex);
-		smb311_update_preauth_hash(ses, &iov, 1);
+		smb311_update_preauth_hash(ses, server, &iov, 1);
 		mutex_unlock(&server->srv_mutex);
+		spin_lock(&cifs_tcp_ses_lock);
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 out:
 	/*
@@ -1353,8 +1371,12 @@ SendReceive(const unsigned int xid, struct cifs_ses *ses,
 		return -EIO;
 	}
 
-	if (server->tcpStatus == CifsExiting)
+	spin_lock(&cifs_tcp_ses_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -ENOENT;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	/* Ensure that we do not send more than 50 overlapping requests
 	   to the same server. We may make this configurable later or
@@ -1494,8 +1516,12 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 		return -EIO;
 	}
 
-	if (server->tcpStatus == CifsExiting)
+	spin_lock(&cifs_tcp_ses_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&cifs_tcp_ses_lock);
 		return -ENOENT;
+	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	/* Ensure that we do not send more than 50 overlapping requests
 	   to the same server. We may make this configurable later or
@@ -1553,10 +1579,12 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 		 (server->tcpStatus != CifsNew)));
 
 	/* Were we interrupted by a signal ? */
+	spin_lock(&cifs_tcp_ses_lock);
 	if ((rc == -ERESTARTSYS) &&
 		(midQ->mid_state == MID_REQUEST_SUBMITTED) &&
 		((server->tcpStatus == CifsGood) ||
 		 (server->tcpStatus == CifsNew))) {
+		spin_unlock(&cifs_tcp_ses_lock);
 
 		if (in_buf->Command == SMB_COM_TRANSACTION2) {
 			/* POSIX lock. We send a NT_CANCEL SMB to cause the
@@ -1595,7 +1623,9 @@ SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
 
 		/* We got the response - restart system call. */
 		rstart = 1;
+		spin_lock(&cifs_tcp_ses_lock);
 	}
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	rc = cifs_sync_mid_result(midQ, server);
 	if (rc != 0)
diff --git a/include/uapi/linux/magic.h b/include/uapi/linux/magic.h
index 8ab81ea13424..dae5df88ab10 100644
--- a/include/uapi/linux/magic.h
+++ b/include/uapi/linux/magic.h
@@ -52,6 +52,7 @@
 #define QNX6_SUPER_MAGIC	0x68191122	/* qnx6 fs detection */
 #define AFS_FS_MAGIC		0x6B414653
 
+
 #define REISERFS_SUPER_MAGIC	0x52654973	/* used by gcc */
 					/* used by file system utilities that
 	                                   look at the superblock, etc.  */
@@ -60,6 +61,9 @@
 #define REISER2FS_JR_SUPER_MAGIC_STRING	"ReIsEr3Fs"
 
 #define SMB_SUPER_MAGIC		0x517B
+#define CIFS_SUPER_MAGIC	0xFF534D42      /* the first four bytes of SMB PDUs */
+#define SMB2_SUPER_MAGIC	0xFE534D42
+
 #define CGROUP_SUPER_MAGIC	0x27e0eb
 #define CGROUP2_SUPER_MAGIC	0x63677270