linux/fs/cifs/connect.c

/*
 *   fs/cifs/connect.c
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2011
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#include <linux/fs.h>
#include <linux/net.h>
#include <linux/string.h>
#include <linux/sched/mm.h>
#include <linux/sched/signal.h>
#include <linux/list.h>
#include <linux/wait.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/ctype.h>
#include <linux/utsname.h>
#include <linux/mempool.h>
#include <linux/delay.h>
#include <linux/completion.h>
#include <linux/kthread.h>
#include <linux/pagevec.h>
#include <linux/freezer.h>
#include <linux/namei.h>
#include <linux/uuid.h>
#include <linux/uaccess.h>
#include <asm/processor.h>
#include <linux/inet.h>
#include <linux/module.h>
#include <keys/user-type.h>
#include <net/ipv6.h>
#include <linux/parser.h>
#include <linux/bvec.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_unicode.h"
#include "cifs_debug.h"
#include "cifs_fs_sb.h"
#include "ntlmssp.h"
#include "nterr.h"
#include "rfc1002pdu.h"
#include "fscache.h"
#include "smb2proto.h"
#include "smbdirect.h"
#include "dns_resolve.h"
#ifdef CONFIG_CIFS_DFS_UPCALL
#include "dfs_cache.h"
#endif
#include "fs_context.h"
#ifdef CONFIG_CIFS_SWN_UPCALL
#include "cifs_swn.h"
#endif

extern mempool_t *cifs_req_poolp;
extern bool disable_legacy_dialects;

/* FIXME: should these be tunable? */
#define TLINK_ERROR_EXPIRE	(1 * HZ)
#define TLINK_IDLE_EXPIRE	(600 * HZ)

/* Drop the connection to not overload the server */
#define NUM_STATUS_IO_TIMEOUT   5

static int ip_connect(struct TCP_Server_Info *server);
static int generic_ip_connect(struct TCP_Server_Info *server);
static void tlink_rb_insert(struct rb_root *root, struct tcon_link *new_tlink);
static void cifs_prune_tlinks(struct work_struct *work);

/*
 * Resolve hostname and set ip addr in tcp ses. Useful for hostnames that may
 * get their ip addresses changed at some point.
 *
 * This should be called with server->srv_mutex held.
 */
#ifdef CONFIG_CIFS_DFS_UPCALL
static int reconn_set_ipaddr_from_hostname(struct TCP_Server_Info *server)
{
	int rc;
	int len;
	char *unc, *ipaddr = NULL;

	if (!server->hostname)
		return -EINVAL;

	len = strlen(server->hostname) + 3;

	unc = kmalloc(len, GFP_KERNEL);
	if (!unc) {
		cifs_dbg(FYI, "%s: failed to create UNC path\n", __func__);
		return -ENOMEM;
	}
	scnprintf(unc, len, "\\\\%s", server->hostname);

	rc = dns_resolve_server_name_to_ip(unc, &ipaddr);
	kfree(unc);

	if (rc < 0) {
		cifs_dbg(FYI, "%s: failed to resolve server part of %s to IP: %d\n",
			 __func__, server->hostname, rc);
		return rc;
	}

	spin_lock(&cifs_tcp_ses_lock);
	rc = cifs_convert_address((struct sockaddr *)&server->dstaddr, ipaddr,
				  strlen(ipaddr));
	spin_unlock(&cifs_tcp_ses_lock);
	kfree(ipaddr);

	return !rc ? -1 : 0;
}

/* These functions must be called with server->srv_mutex held */
static void reconn_set_next_dfs_target(struct TCP_Server_Info *server,
				       struct cifs_sb_info *cifs_sb,
				       struct dfs_cache_tgt_list *tgt_list,
				       struct dfs_cache_tgt_iterator **tgt_it)
{
	const char *name;
	int rc;

	if (!cifs_sb || !cifs_sb->origin_fullpath)
		return;

	if (!*tgt_it) {
		*tgt_it = dfs_cache_get_tgt_iterator(tgt_list);
	} else {
		*tgt_it = dfs_cache_get_next_tgt(tgt_list, *tgt_it);
		if (!*tgt_it)
			*tgt_it = dfs_cache_get_tgt_iterator(tgt_list);
	}

	cifs_dbg(FYI, "%s: UNC: %s\n", __func__, cifs_sb->origin_fullpath);

	name = dfs_cache_get_tgt_name(*tgt_it);

	kfree(server->hostname);

	server->hostname = extract_hostname(name);
	if (IS_ERR(server->hostname)) {
		cifs_dbg(FYI,
			 "%s: failed to extract hostname from target: %ld\n",
			 __func__, PTR_ERR(server->hostname));
		return;
	}

	rc = reconn_set_ipaddr_from_hostname(server);
	if (rc) {
		cifs_dbg(FYI, "%s: failed to resolve hostname: %d\n",
			 __func__, rc);
	}
}

static inline int reconn_setup_dfs_targets(struct cifs_sb_info *cifs_sb,
					   struct dfs_cache_tgt_list *tl)
{
	if (!cifs_sb->origin_fullpath)
		return -EOPNOTSUPP;
	return dfs_cache_noreq_find(cifs_sb->origin_fullpath + 1, NULL, tl);
}
#endif

/*
 * cifs tcp session reconnection
 *
 * mark tcp session as reconnecting so temporarily locked
 * mark all smb sessions as reconnecting for tcp session
 * reconnect tcp session
 * wake up waiters on reconnection? - (not needed currently)
 */
int
cifs_reconnect(struct TCP_Server_Info *server)
{
	int rc = 0;
	struct list_head *tmp, *tmp2;
	struct cifs_ses *ses;
	struct cifs_tcon *tcon;
	struct mid_q_entry *mid_entry;
	struct list_head retry_list;
#ifdef CONFIG_CIFS_DFS_UPCALL
	struct super_block *sb = NULL;
	struct cifs_sb_info *cifs_sb = NULL;
	struct dfs_cache_tgt_list tgt_list = {0};
	struct dfs_cache_tgt_iterator *tgt_it = NULL;
#endif

	spin_lock(&GlobalMid_Lock);
	server->nr_targets = 1;
#ifdef CONFIG_CIFS_DFS_UPCALL
	spin_unlock(&GlobalMid_Lock);
	sb = cifs_get_tcp_super(server);
	if (IS_ERR(sb)) {
		rc = PTR_ERR(sb);
		cifs_dbg(FYI, "%s: will not do DFS failover: rc = %d\n",
			 __func__, rc);
		sb = NULL;
	} else {
		cifs_sb = CIFS_SB(sb);
		rc = reconn_setup_dfs_targets(cifs_sb, &tgt_list);
		if (rc) {
			cifs_sb = NULL;
			if (rc != -EOPNOTSUPP) {
				cifs_server_dbg(VFS, "%s: no target servers for DFS failover\n",
						__func__);
			}
		} else {
			server->nr_targets = dfs_cache_get_nr_tgts(&tgt_list);
		}
	}
	cifs_dbg(FYI, "%s: will retry %d target(s)\n", __func__,
		 server->nr_targets);
	spin_lock(&GlobalMid_Lock);
#endif
	if (server->tcpStatus == CifsExiting) {
		/* the demux thread will exit normally
		next time through the loop */
		spin_unlock(&GlobalMid_Lock);
#ifdef CONFIG_CIFS_DFS_UPCALL
		dfs_cache_free_tgts(&tgt_list);
		cifs_put_tcp_super(sb);
#endif
		wake_up(&server->response_q);
		return rc;
	} else
		server->tcpStatus = CifsNeedReconnect;
	spin_unlock(&GlobalMid_Lock);
	server->maxBuf = 0;
	server->max_read = 0;

	cifs_dbg(FYI, "Mark tcp session as need reconnect\n");
	trace_smb3_reconnect(server->CurrentMid, server->hostname);

	/* 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\n",
		 __func__);
	spin_lock(&cifs_tcp_ses_lock);
	list_for_each(tmp, &server->smb_ses_list) {
		ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
		ses->need_reconnect = true;
		list_for_each(tmp2, &ses->tcon_list) {
			tcon = list_entry(tmp2, struct cifs_tcon, tcon_list);
			tcon->need_reconnect = true;
		}
		if (ses->tcon_ipc)
			ses->tcon_ipc->need_reconnect = true;
	}
	spin_unlock(&cifs_tcp_ses_lock);

	/* 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, server->ssocket->flags);
		kernel_sock_shutdown(server->ssocket, SHUT_WR);
		cifs_dbg(FYI, "Post shutdown state: 0x%x Flags: 0x%lx\n",
			 server->ssocket->state, server->ssocket->flags);
		sock_release(server->ssocket);
		server->ssocket = NULL;
	}
	server->sequence_number = 0;
	server->session_estab = false;
	kfree(server->session_key.response);
	server->session_key.response = NULL;
	server->session_key.len = 0;
	server->lstrp = jiffies;

	/* mark submitted MIDs for retry and issue callback */
	INIT_LIST_HEAD(&retry_list);
	cifs_dbg(FYI, "%s: moving mids to private list\n", __func__);
	spin_lock(&GlobalMid_Lock);
	list_for_each_safe(tmp, tmp2, &server->pending_mid_q) {
		mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
		kref_get(&mid_entry->refcount);
		if (mid_entry->mid_state == MID_REQUEST_SUBMITTED)
			mid_entry->mid_state = MID_RETRY_NEEDED;
		list_move(&mid_entry->qhead, &retry_list);
		mid_entry->mid_flags |= MID_DELETED;
	}
	spin_unlock(&GlobalMid_Lock);
	mutex_unlock(&server->srv_mutex);

	cifs_dbg(FYI, "%s: issuing mid callbacks\n", __func__);
	list_for_each_safe(tmp, tmp2, &retry_list) {
		mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
		list_del_init(&mid_entry->qhead);
		mid_entry->callback(mid_entry);
		cifs_mid_q_entry_release(mid_entry);
	}

	if (cifs_rdma_enabled(server)) {
		mutex_lock(&server->srv_mutex);
		smbd_destroy(server);
		mutex_unlock(&server->srv_mutex);
	}

	do {
		try_to_freeze();

		mutex_lock(&server->srv_mutex);

#ifdef CONFIG_CIFS_SWN_UPCALL
		if (server->use_swn_dstaddr) {
			server->dstaddr = server->swn_dstaddr;
		} else {
#endif

#ifdef CONFIG_CIFS_DFS_UPCALL
			/*
			 * Set up next DFS target server (if any) for reconnect. If DFS
			 * feature is disabled, then we will retry last server we
			 * connected to before.
			 */
			reconn_set_next_dfs_target(server, cifs_sb, &tgt_list, &tgt_it);
#endif

#ifdef CONFIG_CIFS_SWN_UPCALL
		}
#endif

		if (cifs_rdma_enabled(server))
			rc = smbd_reconnect(server);
		else
			rc = generic_ip_connect(server);
		if (rc) {
			cifs_dbg(FYI, "reconnect error %d\n", rc);
			mutex_unlock(&server->srv_mutex);
			msleep(3000);
		} else {
			atomic_inc(&tcpSesReconnectCount);
			set_credits(server, 1);
			spin_lock(&GlobalMid_Lock);
			if (server->tcpStatus != CifsExiting)
				server->tcpStatus = CifsNeedNegotiate;
			spin_unlock(&GlobalMid_Lock);
#ifdef CONFIG_CIFS_SWN_UPCALL
			server->use_swn_dstaddr = false;
#endif
			mutex_unlock(&server->srv_mutex);
		}
	} while (server->tcpStatus == CifsNeedReconnect);

#ifdef CONFIG_CIFS_DFS_UPCALL
	if (tgt_it) {
		rc = dfs_cache_noreq_update_tgthint(cifs_sb->origin_fullpath + 1,
						    tgt_it);
		if (rc) {
			cifs_server_dbg(VFS, "%s: failed to update DFS target hint: rc = %d\n",
				 __func__, rc);
		}
		rc = dfs_cache_update_vol(cifs_sb->origin_fullpath, server);
		if (rc) {
			cifs_server_dbg(VFS, "%s: failed to update vol info in DFS cache: rc = %d\n",
				 __func__, rc);
		}
		dfs_cache_free_tgts(&tgt_list);

	}

	cifs_put_tcp_super(sb);
#endif
	if (server->tcpStatus == CifsNeedNegotiate)
		mod_delayed_work(cifsiod_wq, &server->echo, 0);

	wake_up(&server->response_q);
	return rc;
}

static void
cifs_echo_request(struct work_struct *work)
{
	int rc;
	struct TCP_Server_Info *server = container_of(work,
					struct TCP_Server_Info, echo.work);
	unsigned long echo_interval;

	/*
	 * If we need to renegotiate, set echo interval to zero to
	 * immediately call echo service where we can renegotiate.
	 */
	if (server->tcpStatus == CifsNeedNegotiate)
		echo_interval = 0;
	else
		echo_interval = server->echo_interval;

	/*
	 * We cannot send an echo if it is disabled.
	 * Also, no need to ping if we got a response recently.
	 */

	if (server->tcpStatus == CifsNeedReconnect ||
	    server->tcpStatus == CifsExiting ||
	    server->tcpStatus == CifsNew ||
	    (server->ops->can_echo && !server->ops->can_echo(server)) ||
	    time_before(jiffies, server->lstrp + echo_interval - HZ))
		goto requeue_echo;

	rc = server->ops->echo ? server->ops->echo(server) : -ENOSYS;
	if (rc)
		cifs_dbg(FYI, "Unable to send echo request to server: %s\n",
			 server->hostname);

#ifdef CONFIG_CIFS_SWN_UPCALL
	/* Check witness registrations */
	cifs_swn_check();
#endif

requeue_echo:
	queue_delayed_work(cifsiod_wq, &server->echo, server->echo_interval);
}

static bool
allocate_buffers(struct TCP_Server_Info *server)
{
	if (!server->bigbuf) {
		server->bigbuf = (char *)cifs_buf_get();
		if (!server->bigbuf) {
			cifs_server_dbg(VFS, "No memory for large SMB response\n");
			msleep(3000);
			/* retry will check if exiting */
			return false;
		}
	} else if (server->large_buf) {
		/* we are reusing a dirty large buf, clear its start */
		memset(server->bigbuf, 0, HEADER_SIZE(server));
	}

	if (!server->smallbuf) {
		server->smallbuf = (char *)cifs_small_buf_get();
		if (!server->smallbuf) {
			cifs_server_dbg(VFS, "No memory for SMB response\n");
			msleep(1000);
			/* retry will check if exiting */
			return false;
		}
		/* beginning of smb buffer is cleared in our buf_get */
	} else {
		/* if existing small buf clear beginning */
		memset(server->smallbuf, 0, HEADER_SIZE(server));
	}

	return true;
}

static bool
server_unresponsive(struct TCP_Server_Info *server)
{
	/*
	 * We need to wait 3 echo intervals to make sure we handle such
	 * situations right:
	 * 1s  client sends a normal SMB request
	 * 2s  client gets a response
	 * 30s echo workqueue job pops, and decides we got a response recently
	 *     and don't need to send another
	 * ...
	 * 65s kernel_recvmsg times out, and we see that we haven't gotten
	 *     a response in >60s.
	 */
	if ((server->tcpStatus == CifsGood ||
	    server->tcpStatus == CifsNeedNegotiate) &&
	    time_after(jiffies, server->lstrp + 3 * server->echo_interval)) {
		cifs_server_dbg(VFS, "has not responded in %lu seconds. Reconnecting...\n",
			 (3 * server->echo_interval) / HZ);
		cifs_reconnect(server);
		return true;
	}

	return false;
}

static inline bool
zero_credits(struct TCP_Server_Info *server)
{
	int val;

	spin_lock(&server->req_lock);
	val = server->credits + server->echo_credits + server->oplock_credits;
	if (server->in_flight == 0 && val == 0) {
		spin_unlock(&server->req_lock);
		return true;
	}
	spin_unlock(&server->req_lock);
	return false;
}

static int
cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg)
{
	int length = 0;
	int total_read;

	smb_msg->msg_control = NULL;
	smb_msg->msg_controllen = 0;

	for (total_read = 0; msg_data_left(smb_msg); total_read += length) {
		try_to_freeze();

		/* reconnect if no credits and no requests in flight */
		if (zero_credits(server)) {
			cifs_reconnect(server);
			return -ECONNABORTED;
		}

		if (server_unresponsive(server))
			return -ECONNABORTED;
		if (cifs_rdma_enabled(server) && server->smbd_conn)
			length = smbd_recv(server->smbd_conn, smb_msg);
		else
			length = sock_recvmsg(server->ssocket, smb_msg, 0);

		if (server->tcpStatus == CifsExiting)
			return -ESHUTDOWN;

		if (server->tcpStatus == CifsNeedReconnect) {
			cifs_reconnect(server);
			return -ECONNABORTED;
		}

		if (length == -ERESTARTSYS ||
		    length == -EAGAIN ||
		    length == -EINTR) {
			/*
			 * Minimum sleep to prevent looping, allowing socket
			 * to clear and app threads to set tcpStatus
			 * CifsNeedReconnect if server hung.
			 */
			usleep_range(1000, 2000);
			length = 0;
			continue;
		}

		if (length <= 0) {
			cifs_dbg(FYI, "Received no data or error: %d\n", length);
			cifs_reconnect(server);
			return -ECONNABORTED;
		}
	}
	return total_read;
}

int
cifs_read_from_socket(struct TCP_Server_Info *server, char *buf,
		      unsigned int to_read)
{
	struct msghdr smb_msg;
	struct kvec iov = {.iov_base = buf, .iov_len = to_read};
	iov_iter_kvec(&smb_msg.msg_iter, READ, &iov, 1, to_read);

	return cifs_readv_from_socket(server, &smb_msg);
}

int
cifs_read_page_from_socket(struct TCP_Server_Info *server, struct page *page,
	unsigned int page_offset, unsigned int to_read)
{
	struct msghdr smb_msg;
	struct bio_vec bv = {
		.bv_page = page, .bv_len = to_read, .bv_offset = page_offset};
	iov_iter_bvec(&smb_msg.msg_iter, READ, &bv, 1, to_read);
	return cifs_readv_from_socket(server, &smb_msg);
}

static bool
is_smb_response(struct TCP_Server_Info *server, unsigned char type)
{
	/*
	 * The first byte big endian of the length field,
	 * is actually not part of the length but the type
	 * with the most common, zero, as regular data.
	 */
	switch (type) {
	case RFC1002_SESSION_MESSAGE:
		/* Regular SMB response */
		return true;
	case RFC1002_SESSION_KEEP_ALIVE:
		cifs_dbg(FYI, "RFC 1002 session keep alive\n");
		break;
	case RFC1002_POSITIVE_SESSION_RESPONSE:
		cifs_dbg(FYI, "RFC 1002 positive session response\n");
		break;
	case RFC1002_NEGATIVE_SESSION_RESPONSE:
		/*
		 * We get this from Windows 98 instead of an error on
		 * SMB negprot response.
		 */
		cifs_dbg(FYI, "RFC 1002 negative session response\n");
		/* give server a second to clean up */
		msleep(1000);
		/*
		 * Always try 445 first on reconnect since we get NACK
		 * on some if we ever connected to port 139 (the NACK
		 * is since we do not begin with RFC1001 session
		 * initialize frame).
		 */
		cifs_set_port((struct sockaddr *)&server->dstaddr, CIFS_PORT);
		cifs_reconnect(server);
		break;
	default:
		cifs_server_dbg(VFS, "RFC 1002 unknown response type 0x%x\n", type);
		cifs_reconnect(server);
	}

	return false;
}

void
dequeue_mid(struct mid_q_entry *mid, bool malformed)
{
#ifdef CONFIG_CIFS_STATS2
	mid->when_received = jiffies;
#endif
	spin_lock(&GlobalMid_Lock);
	if (!malformed)
		mid->mid_state = MID_RESPONSE_RECEIVED;
	else
		mid->mid_state = MID_RESPONSE_MALFORMED;
	/*
	 * Trying to handle/dequeue a mid after the send_recv()
	 * function has finished processing it is a bug.
	 */
	if (mid->mid_flags & MID_DELETED)
		pr_warn_once("trying to dequeue a deleted mid\n");
	else {
		list_del_init(&mid->qhead);
		mid->mid_flags |= MID_DELETED;
	}
	spin_unlock(&GlobalMid_Lock);
}

static unsigned int
smb2_get_credits_from_hdr(char *buffer, struct TCP_Server_Info *server)
{
	struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)buffer;

	/*
	 * SMB1 does not use credits.
	 */
	if (server->vals->header_preamble_size)
		return 0;

	return le16_to_cpu(shdr->CreditRequest);
}

static void
handle_mid(struct mid_q_entry *mid, struct TCP_Server_Info *server,
	   char *buf, int malformed)
{
	if (server->ops->check_trans2 &&
	    server->ops->check_trans2(mid, server, buf, malformed))
		return;
	mid->credits_received = smb2_get_credits_from_hdr(buf, server);
	mid->resp_buf = buf;
	mid->large_buf = server->large_buf;
	/* Was previous buf put in mpx struct for multi-rsp? */
	if (!mid->multiRsp) {
		/* smb buffer will be freed by user thread */
		if (server->large_buf)
			server->bigbuf = NULL;
		else
			server->smallbuf = NULL;
	}
	dequeue_mid(mid, malformed);
}

static void clean_demultiplex_info(struct TCP_Server_Info *server)
{
	int length;

	/* take it off the list, if it's not already */
	spin_lock(&cifs_tcp_ses_lock);
	list_del_init(&server->tcp_ses_list);
	spin_unlock(&cifs_tcp_ses_lock);

	cancel_delayed_work_sync(&server->echo);

	spin_lock(&GlobalMid_Lock);
	server->tcpStatus = CifsExiting;
	spin_unlock(&GlobalMid_Lock);
	wake_up_all(&server->response_q);

	/* check if we have blocked requests that need to free */
	spin_lock(&server->req_lock);
	if (server->credits <= 0)
		server->credits = 1;
	spin_unlock(&server->req_lock);
	/*
	 * Although there should not be any requests blocked on this queue it
	 * can not hurt to be paranoid and try to wake up requests that may
	 * haven been blocked when more than 50 at time were on the wire to the
	 * same server - they now will see the session is in exit state and get
	 * out of SendReceive.
	 */
	wake_up_all(&server->request_q);
	/* give those requests time to exit */
	msleep(125);
	if (cifs_rdma_enabled(server))
		smbd_destroy(server);
	if (server->ssocket) {
		sock_release(server->ssocket);
		server->ssocket = NULL;
	}

	if (!list_empty(&server->pending_mid_q)) {
		struct list_head dispose_list;
		struct mid_q_entry *mid_entry;
		struct list_head *tmp, *tmp2;

		INIT_LIST_HEAD(&dispose_list);
		spin_lock(&GlobalMid_Lock);
		list_for_each_safe(tmp, tmp2, &server->pending_mid_q) {
			mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
			cifs_dbg(FYI, "Clearing mid 0x%llx\n", mid_entry->mid);
			kref_get(&mid_entry->refcount);
			mid_entry->mid_state = MID_SHUTDOWN;
			list_move(&mid_entry->qhead, &dispose_list);
			mid_entry->mid_flags |= MID_DELETED;
		}
		spin_unlock(&GlobalMid_Lock);

		/* now walk dispose list and issue callbacks */
		list_for_each_safe(tmp, tmp2, &dispose_list) {
			mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
			cifs_dbg(FYI, "Callback mid 0x%llx\n", mid_entry->mid);
			list_del_init(&mid_entry->qhead);
			mid_entry->callback(mid_entry);
			cifs_mid_q_entry_release(mid_entry);
		}
		/* 1/8th of sec is more than enough time for them to exit */
		msleep(125);
	}

	if (!list_empty(&server->pending_mid_q)) {
		/*
		 * mpx threads have not exited yet give them at least the smb
		 * send timeout time for long ops.
		 *
		 * Due to delays on oplock break requests, we need to wait at
		 * least 45 seconds before giving up on a request getting a
		 * response and going ahead and killing cifsd.
		 */
		cifs_dbg(FYI, "Wait for exit from demultiplex thread\n");
		msleep(46000);
		/*
		 * If threads still have not exited they are probably never
		 * coming home not much else we can do but free the memory.
		 */
	}

	kfree(server->hostname);
	kfree(server);

	length = atomic_dec_return(&tcpSesAllocCount);
	if (length > 0)
		mempool_resize(cifs_req_poolp, length + cifs_min_rcv);
}

static int
standard_receive3(struct TCP_Server_Info *server, struct mid_q_entry *mid)
{
	int length;
	char *buf = server->smallbuf;
	unsigned int pdu_length = server->pdu_size;

	/* make sure this will fit in a large buffer */
	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);
		return -ECONNABORTED;
	}

	/* switch to large buffer if too big for a small one */
	if (pdu_length > MAX_CIFS_SMALL_BUFFER_SIZE - 4) {
		server->large_buf = true;
		memcpy(server->bigbuf, buf, server->total_read);
		buf = server->bigbuf;
	}

	/* now read the rest */
	length = cifs_read_from_socket(server, buf + HEADER_SIZE(server) - 1,
				       pdu_length - HEADER_SIZE(server) + 1
				       + server->vals->header_preamble_size);

	if (length < 0)
		return length;
	server->total_read += length;

	dump_smb(buf, server->total_read);

	return cifs_handle_standard(server, mid);
}

int
cifs_handle_standard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
{
	char *buf = server->large_buf ? server->bigbuf : server->smallbuf;
	int length;

	/*
	 * We know that we received enough to get to the MID as we
	 * checked the pdu_length earlier. Now check to see
	 * if the rest of the header is OK. We borrow the length
	 * var for the rest of the loop to avoid a new stack var.
	 *
	 * 48 bytes is enough to display the header and a little bit
	 * into the payload for debugging purposes.
	 */
	length = server->ops->check_message(buf, server->total_read, server);
	if (length != 0)
		cifs_dump_mem("Bad SMB: ", buf,
			min_t(unsigned int, server->total_read, 48));

	if (server->ops->is_session_expired &&
	    server->ops->is_session_expired(buf)) {
		cifs_reconnect(server);
		return -1;
	}

	if (server->ops->is_status_pending &&
	    server->ops->is_status_pending(buf, server))
		return -1;

	if (!mid)
		return length;

	handle_mid(mid, server, buf, length);
	return 0;
}

static void
smb2_add_credits_from_hdr(char *buffer, struct TCP_Server_Info *server)
{
	struct smb2_sync_hdr *shdr = (struct smb2_sync_hdr *)buffer;
	int scredits = server->credits;

	/*
	 * SMB1 does not use credits.
	 */
	if (server->vals->header_preamble_size)
		return;

	if (shdr->CreditRequest) {
		spin_lock(&server->req_lock);
		server->credits += le16_to_cpu(shdr->CreditRequest);
		spin_unlock(&server->req_lock);
		wake_up(&server->request_q);

		trace_smb3_add_credits(server->CurrentMid,
				server->hostname, scredits,
				le16_to_cpu(shdr->CreditRequest));
		cifs_server_dbg(FYI, "%s: added %u credits total=%d\n",
				__func__, le16_to_cpu(shdr->CreditRequest),
				scredits);
	}
}


static int
cifs_demultiplex_thread(void *p)
{
	int i, num_mids, length;
	struct TCP_Server_Info *server = p;
	unsigned int pdu_length;
	unsigned int next_offset;
	char *buf = NULL;
	struct task_struct *task_to_wake = NULL;
	struct mid_q_entry *mids[MAX_COMPOUND];
	char *bufs[MAX_COMPOUND];
	unsigned int noreclaim_flag, num_io_timeout = 0;

	noreclaim_flag = memalloc_noreclaim_save();
	cifs_dbg(FYI, "Demultiplex PID: %d\n", task_pid_nr(current));

	length = atomic_inc_return(&tcpSesAllocCount);
	if (length > 1)
		mempool_resize(cifs_req_poolp, length + cifs_min_rcv);

	set_freezable();
	allow_kernel_signal(SIGKILL);
	while (server->tcpStatus != CifsExiting) {
		if (try_to_freeze())
			continue;

		if (!allocate_buffers(server))
			continue;

		server->large_buf = false;
		buf = server->smallbuf;
		pdu_length = 4; /* enough to get RFC1001 header */

		length = cifs_read_from_socket(server, buf, pdu_length);
		if (length < 0)
			continue;

		if (server->vals->header_preamble_size == 0)
			server->total_read = 0;
		else
			server->total_read = length;

		/*
		 * The right amount was read from socket - 4 bytes,
		 * so we can now interpret the length field.
		 */
		pdu_length = get_rfc1002_length(buf);

		cifs_dbg(FYI, "RFC1002 header 0x%x\n", pdu_length);
		if (!is_smb_response(server, buf[0]))
			continue;
next_pdu:
		server->pdu_size = pdu_length;

		/* make sure we have enough to get to the MID */
		if (server->pdu_size < HEADER_SIZE(server) - 1 -
		    server->vals->header_preamble_size) {
			cifs_server_dbg(VFS, "SMB response too short (%u bytes)\n",
				 server->pdu_size);
			cifs_reconnect(server);
			continue;
		}

		/* read down to the MID */
		length = cifs_read_from_socket(server,
			     buf + server->vals->header_preamble_size,
			     HEADER_SIZE(server) - 1
			     - server->vals->header_preamble_size);
		if (length < 0)
			continue;
		server->total_read += length;

		if (server->ops->next_header) {
			next_offset = server->ops->next_header(buf);
			if (next_offset)
				server->pdu_size = next_offset;
		}

		memset(mids, 0, sizeof(mids));
		memset(bufs, 0, sizeof(bufs));
		num_mids = 0;

		if (server->ops->is_transform_hdr &&
		    server->ops->receive_transform &&
		    server->ops->is_transform_hdr(buf)) {
			length = server->ops->receive_transform(server,
								mids,
								bufs,
								&num_mids);
		} else {
			mids[0] = server->ops->find_mid(server, buf);
			bufs[0] = buf;
			num_mids = 1;

			if (!mids[0] || !mids[0]->receive)
				length = standard_receive3(server, mids[0]);
			else
				length = mids[0]->receive(server, mids[0]);
		}

		if (length < 0) {
			for (i = 0; i < num_mids; i++)
				if (mids[i])
					cifs_mid_q_entry_release(mids[i]);
			continue;
		}

		if (server->ops->is_status_io_timeout &&
		    server->ops->is_status_io_timeout(buf)) {
			num_io_timeout++;
			if (num_io_timeout > NUM_STATUS_IO_TIMEOUT) {
				cifs_reconnect(server);
				num_io_timeout = 0;
				continue;
			}
		}

		server->lstrp = jiffies;

		for (i = 0; i < num_mids; i++) {
			if (mids[i] != NULL) {
				mids[i]->resp_buf_size = server->pdu_size;

				if (!mids[i]->multiRsp || mids[i]->multiEnd)
					mids[i]->callback(mids[i]);

				cifs_mid_q_entry_release(mids[i]);
			} else if (server->ops->is_oplock_break &&
				   server->ops->is_oplock_break(bufs[i],
								server)) {
				smb2_add_credits_from_hdr(bufs[i], server);
				cifs_dbg(FYI, "Received oplock break\n");
			} else {
				cifs_server_dbg(VFS, "No task to wake, unknown frame received! NumMids %d\n",
						atomic_read(&midCount));
				cifs_dump_mem("Received Data is: ", bufs[i],
					      HEADER_SIZE(server));
				smb2_add_credits_from_hdr(bufs[i], server);
#ifdef CONFIG_CIFS_DEBUG2
				if (server->ops->dump_detail)
					server->ops->dump_detail(bufs[i],
								 server);
				cifs_dump_mids(server);
#endif /* CIFS_DEBUG2 */
			}
		}

		if (pdu_length > server->pdu_size) {
			if (!allocate_buffers(server))
				continue;
			pdu_length -= server->pdu_size;
			server->total_read = 0;
			server->large_buf = false;
			buf = server->smallbuf;
			goto next_pdu;
		}
	} /* end while !EXITING */

	/* buffer usually freed in free_mid - need to free it here on exit */
	cifs_buf_release(server->bigbuf);
	if (server->smallbuf) /* no sense logging a debug message if NULL */
		cifs_small_buf_release(server->smallbuf);

	task_to_wake = xchg(&server->tsk, NULL);
	clean_demultiplex_info(server);

	/* if server->tsk was NULL then wait for a signal before exiting */
	if (!task_to_wake) {
		set_current_state(TASK_INTERRUPTIBLE);
		while (!signal_pending(current)) {
			schedule();
			set_current_state(TASK_INTERRUPTIBLE);
		}
		set_current_state(TASK_RUNNING);
	}

	memalloc_noreclaim_restore(noreclaim_flag);
	module_put_and_exit(0);
}

/**
 * Returns true if srcaddr isn't specified and rhs isn't specified, or
 * if srcaddr is specified and matches the IP address of the rhs argument
 */
bool
cifs_match_ipaddr(struct sockaddr *srcaddr, struct sockaddr *rhs)
{
	switch (srcaddr->sa_family) {
	case AF_UNSPEC:
		return (rhs->sa_family == AF_UNSPEC);
	case AF_INET: {
		struct sockaddr_in *saddr4 = (struct sockaddr_in *)srcaddr;
		struct sockaddr_in *vaddr4 = (struct sockaddr_in *)rhs;
		return (saddr4->sin_addr.s_addr == vaddr4->sin_addr.s_addr);
	}
	case AF_INET6: {
		struct sockaddr_in6 *saddr6 = (struct sockaddr_in6 *)srcaddr;
		struct sockaddr_in6 *vaddr6 = (struct sockaddr_in6 *)rhs;
		return ipv6_addr_equal(&saddr6->sin6_addr, &vaddr6->sin6_addr);
	}
	default:
		WARN_ON(1);
		return false; /* don't expect to be here */
	}
}

/*
 * If no port is specified in addr structure, we try to match with 445 port
 * and if it fails - with 139 ports. It should be called only if address
 * families of server and addr are equal.
 */
static bool
match_port(struct TCP_Server_Info *server, struct sockaddr *addr)
{
	__be16 port, *sport;

	/* SMBDirect manages its own ports, don't match it here */
	if (server->rdma)
		return true;

	switch (addr->sa_family) {
	case AF_INET:
		sport = &((struct sockaddr_in *) &server->dstaddr)->sin_port;
		port = ((struct sockaddr_in *) addr)->sin_port;
		break;
	case AF_INET6:
		sport = &((struct sockaddr_in6 *) &server->dstaddr)->sin6_port;
		port = ((struct sockaddr_in6 *) addr)->sin6_port;
		break;
	default:
		WARN_ON(1);
		return false;
	}

	if (!port) {
		port = htons(CIFS_PORT);
		if (port == *sport)
			return true;

		port = htons(RFC1001_PORT);
	}

	return port == *sport;
}

static bool
match_address(struct TCP_Server_Info *server, struct sockaddr *addr,
	      struct sockaddr *srcaddr)
{
	switch (addr->sa_family) {
	case AF_INET: {
		struct sockaddr_in *addr4 = (struct sockaddr_in *)addr;
		struct sockaddr_in *srv_addr4 =
					(struct sockaddr_in *)&server->dstaddr;

		if (addr4->sin_addr.s_addr != srv_addr4->sin_addr.s_addr)
			return false;
		break;
	}
	case AF_INET6: {
		struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)addr;
		struct sockaddr_in6 *srv_addr6 =
					(struct sockaddr_in6 *)&server->dstaddr;

		if (!ipv6_addr_equal(&addr6->sin6_addr,
				     &srv_addr6->sin6_addr))
			return false;
		if (addr6->sin6_scope_id != srv_addr6->sin6_scope_id)
			return false;
		break;
	}
	default:
		WARN_ON(1);
		return false; /* don't expect to be here */
	}

	if (!cifs_match_ipaddr(srcaddr, (struct sockaddr *)&server->srcaddr))
		return false;

	return true;
}

static bool
match_security(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
{
	/*
	 * The select_sectype function should either return the ctx->sectype
	 * that was specified, or "Unspecified" if that sectype was not
	 * compatible with the given NEGOTIATE request.
	 */
	if (server->ops->select_sectype(server, ctx->sectype)
	     == Unspecified)
		return false;

	/*
	 * Now check if signing mode is acceptable. No need to check
	 * global_secflags at this point since if MUST_SIGN is set then
	 * the server->sign had better be too.
	 */
	if (ctx->sign && !server->sign)
		return false;

	return true;
}

static int match_server(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
{
	struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr;

	if (ctx->nosharesock)
		return 0;

	/* If multidialect negotiation see if existing sessions match one */
	if (strcmp(ctx->vals->version_string, SMB3ANY_VERSION_STRING) == 0) {
		if (server->vals->protocol_id < SMB30_PROT_ID)
			return 0;
	} else if (strcmp(ctx->vals->version_string,
		   SMBDEFAULT_VERSION_STRING) == 0) {
		if (server->vals->protocol_id < SMB21_PROT_ID)
			return 0;
	} else if ((server->vals != ctx->vals) || (server->ops != ctx->ops))
		return 0;

	if (!net_eq(cifs_net_ns(server), current->nsproxy->net_ns))
		return 0;

	if (!match_address(server, addr,
			   (struct sockaddr *)&ctx->srcaddr))
		return 0;

	if (!match_port(server, addr))
		return 0;

	if (!match_security(server, ctx))
		return 0;

	if (server->echo_interval != ctx->echo_interval * HZ)
		return 0;

	if (server->rdma != ctx->rdma)
		return 0;

	if (server->ignore_signature != ctx->ignore_signature)
		return 0;

	if (server->min_offload != ctx->min_offload)
		return 0;

	return 1;
}

struct TCP_Server_Info *
cifs_find_tcp_session(struct smb3_fs_context *ctx)
{
	struct TCP_Server_Info *server;

	spin_lock(&cifs_tcp_ses_lock);
	list_for_each_entry(server, &cifs_tcp_ses_list, tcp_ses_list) {
		/*
		 * Skip ses channels since they're only handled in lower layers
		 * (e.g. cifs_send_recv).
		 */
		if (server->is_channel || !match_server(server, ctx))
			continue;

		++server->srv_count;
		spin_unlock(&cifs_tcp_ses_lock);
		cifs_dbg(FYI, "Existing tcp session with server found\n");
		return server;
	}
	spin_unlock(&cifs_tcp_ses_lock);
	return NULL;
}

void
cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
{
	struct task_struct *task;

	spin_lock(&cifs_tcp_ses_lock);
	if (--server->srv_count > 0) {
		spin_unlock(&cifs_tcp_ses_lock);
		return;
	}

	put_net(cifs_net_ns(server));

	list_del_init(&server->tcp_ses_list);
	spin_unlock(&cifs_tcp_ses_lock);

	cancel_delayed_work_sync(&server->echo);

	if (from_reconnect)
		/*
		 * Avoid deadlock here: reconnect work calls
		 * cifs_put_tcp_session() at its end. Need to be sure
		 * that reconnect work does nothing with server pointer after
		 * that step.
		 */
		cancel_delayed_work(&server->reconnect);
	else
		cancel_delayed_work_sync(&server->reconnect);

	spin_lock(&GlobalMid_Lock);
	server->tcpStatus = CifsExiting;
	spin_unlock(&GlobalMid_Lock);

	cifs_crypto_secmech_release(server);
	cifs_fscache_release_client_cookie(server);

	kfree(server->session_key.response);
	server->session_key.response = NULL;
	server->session_key.len = 0;

	task = xchg(&server->tsk, NULL);
	if (task)
		send_sig(SIGKILL, task, 1);
}

struct TCP_Server_Info *
cifs_get_tcp_session(struct smb3_fs_context *ctx)
{
	struct TCP_Server_Info *tcp_ses = NULL;
	int rc;

	cifs_dbg(FYI, "UNC: %s\n", ctx->UNC);

	/* see if we already have a matching tcp_ses */
	tcp_ses = cifs_find_tcp_session(ctx);
	if (tcp_ses)
		return tcp_ses;

	tcp_ses = kzalloc(sizeof(struct TCP_Server_Info), GFP_KERNEL);
	if (!tcp_ses) {
		rc = -ENOMEM;
		goto out_err;
	}

	tcp_ses->ops = ctx->ops;
	tcp_ses->vals = ctx->vals;
	cifs_set_net_ns(tcp_ses, get_net(current->nsproxy->net_ns));
	tcp_ses->hostname = extract_hostname(ctx->UNC);
	if (IS_ERR(tcp_ses->hostname)) {
		rc = PTR_ERR(tcp_ses->hostname);
		goto out_err_crypto_release;
	}

	tcp_ses->noblockcnt = ctx->rootfs;
	tcp_ses->noblocksnd = ctx->noblocksnd || ctx->rootfs;
	tcp_ses->noautotune = ctx->noautotune;
	tcp_ses->tcp_nodelay = ctx->sockopt_tcp_nodelay;
	tcp_ses->rdma = ctx->rdma;
	tcp_ses->in_flight = 0;
	tcp_ses->max_in_flight = 0;
	tcp_ses->credits = 1;
	init_waitqueue_head(&tcp_ses->response_q);
	init_waitqueue_head(&tcp_ses->request_q);
	INIT_LIST_HEAD(&tcp_ses->pending_mid_q);
	mutex_init(&tcp_ses->srv_mutex);
	memcpy(tcp_ses->workstation_RFC1001_name,
		ctx->source_rfc1001_name, RFC1001_NAME_LEN_WITH_NULL);
	memcpy(tcp_ses->server_RFC1001_name,
		ctx->target_rfc1001_name, RFC1001_NAME_LEN_WITH_NULL);
	tcp_ses->session_estab = false;
	tcp_ses->sequence_number = 0;
	tcp_ses->reconnect_instance = 1;
	tcp_ses->lstrp = jiffies;
	tcp_ses->compress_algorithm = cpu_to_le16(ctx->compression);
	spin_lock_init(&tcp_ses->req_lock);
	INIT_LIST_HEAD(&tcp_ses->tcp_ses_list);
	INIT_LIST_HEAD(&tcp_ses->smb_ses_list);
	INIT_DELAYED_WORK(&tcp_ses->echo, cifs_echo_request);
	INIT_DELAYED_WORK(&tcp_ses->reconnect, smb2_reconnect_server);
	mutex_init(&tcp_ses->reconnect_mutex);
	memcpy(&tcp_ses->srcaddr, &ctx->srcaddr,
	       sizeof(tcp_ses->srcaddr));
	memcpy(&tcp_ses->dstaddr, &ctx->dstaddr,
		sizeof(tcp_ses->dstaddr));
	if (ctx->use_client_guid)
		memcpy(tcp_ses->client_guid, ctx->client_guid,
		       SMB2_CLIENT_GUID_SIZE);
	else
		generate_random_uuid(tcp_ses->client_guid);
	/*
	 * at this point we are the only ones with the pointer
	 * to the struct since the kernel thread not created yet
	 * no need to spinlock this init of tcpStatus or srv_count
	 */
	tcp_ses->tcpStatus = CifsNew;
	++tcp_ses->srv_count;

	if (ctx->echo_interval >= SMB_ECHO_INTERVAL_MIN &&
		ctx->echo_interval <= SMB_ECHO_INTERVAL_MAX)
		tcp_ses->echo_interval = ctx->echo_interval * HZ;
	else
		tcp_ses->echo_interval = SMB_ECHO_INTERVAL_DEFAULT * HZ;
	if (tcp_ses->rdma) {
#ifndef CONFIG_CIFS_SMB_DIRECT
		cifs_dbg(VFS, "CONFIG_CIFS_SMB_DIRECT is not enabled\n");
		rc = -ENOENT;
		goto out_err_crypto_release;
#endif
		tcp_ses->smbd_conn = smbd_get_connection(
			tcp_ses, (struct sockaddr *)&ctx->dstaddr);
		if (tcp_ses->smbd_conn) {
			cifs_dbg(VFS, "RDMA transport established\n");
			rc = 0;
			goto smbd_connected;
		} else {
			rc = -ENOENT;
			goto out_err_crypto_release;
		}
	}
	rc = ip_connect(tcp_ses);
	if (rc < 0) {
		cifs_dbg(VFS, "Error connecting to socket. Aborting operation.\n");
		goto out_err_crypto_release;
	}
smbd_connected:
	/*
	 * since we're in a cifs function already, we know that
	 * this will succeed. No need for try_module_get().
	 */
	__module_get(THIS_MODULE);
	tcp_ses->tsk = kthread_run(cifs_demultiplex_thread,
				  tcp_ses, "cifsd");
	if (IS_ERR(tcp_ses->tsk)) {
		rc = PTR_ERR(tcp_ses->tsk);
		cifs_dbg(VFS, "error %d create cifsd thread\n", rc);
		module_put(THIS_MODULE);
		goto out_err_crypto_release;
	}
	tcp_ses->min_offload = ctx->min_offload;
	tcp_ses->tcpStatus = CifsNeedNegotiate;

	tcp_ses->nr_targets = 1;
	tcp_ses->ignore_signature = ctx->ignore_signature;
	/* thread spawned, put it on the list */
	spin_lock(&cifs_tcp_ses_lock);
	list_add(&tcp_ses->tcp_ses_list, &cifs_tcp_ses_list);
	spin_unlock(&cifs_tcp_ses_lock);

	cifs_fscache_get_client_cookie(tcp_ses);

	/* queue echo request delayed work */
	queue_delayed_work(cifsiod_wq, &tcp_ses->echo, tcp_ses->echo_interval);

	return tcp_ses;

out_err_crypto_release:
	cifs_crypto_secmech_release(tcp_ses);

	put_net(cifs_net_ns(tcp_ses));

out_err:
	if (tcp_ses) {
		if (!IS_ERR(tcp_ses->hostname))
			kfree(tcp_ses->hostname);
		if (tcp_ses->ssocket)
			sock_release(tcp_ses->ssocket);
		kfree(tcp_ses);
	}
	return ERR_PTR(rc);
}

static int match_session(struct cifs_ses *ses, struct smb3_fs_context *ctx)
{
	if (ctx->sectype != Unspecified &&
	    ctx->sectype != ses->sectype)
		return 0;

	/*
	 * If an existing session is limited to less channels than
	 * requested, it should not be reused
	 */
	if (ses->chan_max < ctx->max_channels)
		return 0;

	switch (ses->sectype) {
	case Kerberos:
		if (!uid_eq(ctx->cred_uid, ses->cred_uid))
			return 0;
		break;
	default:
		/* NULL username means anonymous session */
		if (ses->user_name == NULL) {
			if (!ctx->nullauth)
				return 0;
			break;
		}

		/* anything else takes username/password */
		if (strncmp(ses->user_name,
			    ctx->username ? ctx->username : "",
			    CIFS_MAX_USERNAME_LEN))
			return 0;
		if ((ctx->username && strlen(ctx->username) != 0) &&
		    ses->password != NULL &&
		    strncmp(ses->password,
			    ctx->password ? ctx->password : "",
			    CIFS_MAX_PASSWORD_LEN))
			return 0;
	}
	return 1;
}

/**
 * cifs_setup_ipc - helper to setup the IPC tcon for the session
 *
 * A new IPC connection is made and stored in the session
 * tcon_ipc. The IPC tcon has the same lifetime as the session.
 */
static int
cifs_setup_ipc(struct cifs_ses *ses, struct smb3_fs_context *ctx)
{
	int rc = 0, xid;
	struct cifs_tcon *tcon;
	char unc[SERVER_NAME_LENGTH + sizeof("//x/IPC$")] = {0};
	bool seal = false;
	struct TCP_Server_Info *server = ses->server;

	/*
	 * If the mount request that resulted in the creation of the
	 * session requires encryption, force IPC to be encrypted too.
	 */
	if (ctx->seal) {
		if (server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION)
			seal = true;
		else {
			cifs_server_dbg(VFS,
				 "IPC: server doesn't support encryption\n");
			return -EOPNOTSUPP;
		}
	}

	tcon = tconInfoAlloc();
	if (tcon == NULL)
		return -ENOMEM;

	scnprintf(unc, sizeof(unc), "\\\\%s\\IPC$", server->hostname);

	xid = get_xid();
	tcon->ses = ses;
	tcon->ipc = true;
	tcon->seal = seal;
	rc = server->ops->tree_connect(xid, ses, unc, tcon, ctx->local_nls);
	free_xid(xid);

	if (rc) {
		cifs_server_dbg(VFS, "failed to connect to IPC (rc=%d)\n", rc);
		tconInfoFree(tcon);
		goto out;
	}

	cifs_dbg(FYI, "IPC tcon rc = %d ipc tid = %d\n", rc, tcon->tid);

	ses->tcon_ipc = tcon;
out:
	return rc;
}

/**
 * cifs_free_ipc - helper to release the session IPC tcon
 *
 * Needs to be called everytime a session is destroyed
 */
static int
cifs_free_ipc(struct cifs_ses *ses)
{
	int rc = 0, xid;
	struct cifs_tcon *tcon = ses->tcon_ipc;

	if (tcon == NULL)
		return 0;

	if (ses->server->ops->tree_disconnect) {
		xid = get_xid();
		rc = ses->server->ops->tree_disconnect(xid, tcon);
		free_xid(xid);
	}

	if (rc)
		cifs_dbg(FYI, "failed to disconnect IPC tcon (rc=%d)\n", rc);

	tconInfoFree(tcon);
	ses->tcon_ipc = NULL;
	return rc;
}

static struct cifs_ses *
cifs_find_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
{
	struct cifs_ses *ses;

	spin_lock(&cifs_tcp_ses_lock);
	list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
		if (ses->status == CifsExiting)
			continue;
		if (!match_session(ses, ctx))
			continue;
		++ses->ses_count;
		spin_unlock(&cifs_tcp_ses_lock);
		return ses;
	}
	spin_unlock(&cifs_tcp_ses_lock);
	return NULL;
}

void cifs_put_smb_ses(struct cifs_ses *ses)
{
	unsigned int rc, xid;
	struct TCP_Server_Info *server = ses->server;

	cifs_dbg(FYI, "%s: ses_count=%d\n", __func__, ses->ses_count);

	spin_lock(&cifs_tcp_ses_lock);
	if (ses->status == CifsExiting) {
		spin_unlock(&cifs_tcp_ses_lock);
		return;
	}
	if (--ses->ses_count > 0) {
		spin_unlock(&cifs_tcp_ses_lock);
		return;
	}
	if (ses->status == CifsGood)
		ses->status = CifsExiting;
	spin_unlock(&cifs_tcp_ses_lock);

	cifs_free_ipc(ses);

	if (ses->status == CifsExiting && server->ops->logoff) {
		xid = get_xid();
		rc = server->ops->logoff(xid, ses);
		if (rc)
			cifs_server_dbg(VFS, "%s: Session Logoff failure rc=%d\n",
				__func__, rc);
		_free_xid(xid);
	}

	spin_lock(&cifs_tcp_ses_lock);
	list_del_init(&ses->smb_ses_list);
	spin_unlock(&cifs_tcp_ses_lock);

	/* close any extra channels */
	if (ses->chan_count > 1) {
		int i;

		for (i = 1; i < ses->chan_count; i++)
			cifs_put_tcp_session(ses->chans[i].server, 0);
	}

	sesInfoFree(ses);
	cifs_put_tcp_session(server, 0);
}

#ifdef CONFIG_KEYS

/* strlen("cifs:a:") + CIFS_MAX_DOMAINNAME_LEN + 1 */
#define CIFSCREDS_DESC_SIZE (7 + CIFS_MAX_DOMAINNAME_LEN + 1)

/* Populate username and pw fields from keyring if possible */
static int
cifs_set_cifscreds(struct smb3_fs_context *ctx, struct cifs_ses *ses)
{
	int rc = 0;
	int is_domain = 0;
	const char *delim, *payload;
	char *desc;
	ssize_t len;
	struct key *key;
	struct TCP_Server_Info *server = ses->server;
	struct sockaddr_in *sa;
	struct sockaddr_in6 *sa6;
	const struct user_key_payload *upayload;

	desc = kmalloc(CIFSCREDS_DESC_SIZE, GFP_KERNEL);
	if (!desc)
		return -ENOMEM;

	/* try to find an address key first */
	switch (server->dstaddr.ss_family) {
	case AF_INET:
		sa = (struct sockaddr_in *)&server->dstaddr;
		sprintf(desc, "cifs:a:%pI4", &sa->sin_addr.s_addr);
		break;
	case AF_INET6:
		sa6 = (struct sockaddr_in6 *)&server->dstaddr;
		sprintf(desc, "cifs:a:%pI6c", &sa6->sin6_addr.s6_addr);
		break;
	default:
		cifs_dbg(FYI, "Bad ss_family (%hu)\n",
			 server->dstaddr.ss_family);
		rc = -EINVAL;
		goto out_err;
	}

	cifs_dbg(FYI, "%s: desc=%s\n", __func__, desc);
	key = request_key(&key_type_logon, desc, "");
	if (IS_ERR(key)) {
		if (!ses->domainName) {
			cifs_dbg(FYI, "domainName is NULL\n");
			rc = PTR_ERR(key);
			goto out_err;
		}

		/* didn't work, try to find a domain key */
		sprintf(desc, "cifs:d:%s", ses->domainName);
		cifs_dbg(FYI, "%s: desc=%s\n", __func__, desc);
		key = request_key(&key_type_logon, desc, "");
		if (IS_ERR(key)) {
			rc = PTR_ERR(key);
			goto out_err;
		}
		is_domain = 1;
	}

	down_read(&key->sem);
	upayload = user_key_payload_locked(key);
	if (IS_ERR_OR_NULL(upayload)) {
		rc = upayload ? PTR_ERR(upayload) : -EINVAL;
		goto out_key_put;
	}

	/* find first : in payload */
	payload = upayload->data;
	delim = strnchr(payload, upayload->datalen, ':');
	cifs_dbg(FYI, "payload=%s\n", payload);
	if (!delim) {
		cifs_dbg(FYI, "Unable to find ':' in payload (datalen=%d)\n",
			 upayload->datalen);
		rc = -EINVAL;
		goto out_key_put;
	}

	len = delim - payload;
	if (len > CIFS_MAX_USERNAME_LEN || len <= 0) {
		cifs_dbg(FYI, "Bad value from username search (len=%zd)\n",
			 len);
		rc = -EINVAL;
		goto out_key_put;
	}

	ctx->username = kstrndup(payload, len, GFP_KERNEL);
	if (!ctx->username) {
		cifs_dbg(FYI, "Unable to allocate %zd bytes for username\n",
			 len);
		rc = -ENOMEM;
		goto out_key_put;
	}
	cifs_dbg(FYI, "%s: username=%s\n", __func__, ctx->username);

	len = key->datalen - (len + 1);
	if (len > CIFS_MAX_PASSWORD_LEN || len <= 0) {
		cifs_dbg(FYI, "Bad len for password search (len=%zd)\n", len);
		rc = -EINVAL;
		kfree(ctx->username);
		ctx->username = NULL;
		goto out_key_put;
	}

	++delim;
	ctx->password = kstrndup(delim, len, GFP_KERNEL);
	if (!ctx->password) {
		cifs_dbg(FYI, "Unable to allocate %zd bytes for password\n",
			 len);
		rc = -ENOMEM;
		kfree(ctx->username);
		ctx->username = NULL;
		goto out_key_put;
	}

	/*
	 * If we have a domain key then we must set the domainName in the
	 * for the request.
	 */
	if (is_domain && ses->domainName) {
		ctx->domainname = kstrndup(ses->domainName,
					   strlen(ses->domainName),
					   GFP_KERNEL);
		if (!ctx->domainname) {
			cifs_dbg(FYI, "Unable to allocate %zd bytes for domain\n",
				 len);
			rc = -ENOMEM;
			kfree(ctx->username);
			ctx->username = NULL;
			kfree_sensitive(ctx->password);
			ctx->password = NULL;
			goto out_key_put;
		}
	}

out_key_put:
	up_read(&key->sem);
	key_put(key);
out_err:
	kfree(desc);
	cifs_dbg(FYI, "%s: returning %d\n", __func__, rc);
	return rc;
}
#else /* ! CONFIG_KEYS */
static inline int
cifs_set_cifscreds(struct smb3_fs_context *ctx __attribute__((unused)),
		   struct cifs_ses *ses __attribute__((unused)))
{
	return -ENOSYS;
}
#endif /* CONFIG_KEYS */

/**
 * cifs_get_smb_ses - get a session matching @ctx data from @server
 *
 * This function assumes it is being called from cifs_mount() where we
 * already got a server reference (server refcount +1). See
 * cifs_get_tcon() for refcount explanations.
 */
struct cifs_ses *
cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb3_fs_context *ctx)
{
	int rc = -ENOMEM;
	unsigned int xid;
	struct cifs_ses *ses;
	struct sockaddr_in *addr = (struct sockaddr_in *)&server->dstaddr;
	struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&server->dstaddr;

	xid = get_xid();

	ses = cifs_find_smb_ses(server, ctx);
	if (ses) {
		cifs_dbg(FYI, "Existing smb sess found (status=%d)\n",
			 ses->status);

		mutex_lock(&ses->session_mutex);
		rc = cifs_negotiate_protocol(xid, ses);
		if (rc) {
			mutex_unlock(&ses->session_mutex);
			/* problem -- put our ses reference */
			cifs_put_smb_ses(ses);
			free_xid(xid);
			return ERR_PTR(rc);
		}
		if (ses->need_reconnect) {
			cifs_dbg(FYI, "Session needs reconnect\n");
			rc = cifs_setup_session(xid, ses,
						ctx->local_nls);
			if (rc) {
				mutex_unlock(&ses->session_mutex);
				/* problem -- put our reference */
				cifs_put_smb_ses(ses);
				free_xid(xid);
				return ERR_PTR(rc);
			}
		}
		mutex_unlock(&ses->session_mutex);

		/* existing SMB ses has a server reference already */
		cifs_put_tcp_session(server, 0);
		free_xid(xid);
		return ses;
	}

	cifs_dbg(FYI, "Existing smb sess not found\n");
	ses = sesInfoAlloc();
	if (ses == NULL)
		goto get_ses_fail;

	/* new SMB session uses our server ref */
	ses->server = server;
	if (server->dstaddr.ss_family == AF_INET6)
		sprintf(ses->serverName, "%pI6", &addr6->sin6_addr);
	else
		sprintf(ses->serverName, "%pI4", &addr->sin_addr);

	if (ctx->username) {
		ses->user_name = kstrdup(ctx->username, GFP_KERNEL);
		if (!ses->user_name)
			goto get_ses_fail;
	}

	/* ctx->password freed at unmount */
	if (ctx->password) {
		ses->password = kstrdup(ctx->password, GFP_KERNEL);
		if (!ses->password)
			goto get_ses_fail;
	}
	if (ctx->domainname) {
		ses->domainName = kstrdup(ctx->domainname, GFP_KERNEL);
		if (!ses->domainName)
			goto get_ses_fail;
	}
	if (ctx->domainauto)
		ses->domainAuto = ctx->domainauto;
	ses->cred_uid = ctx->cred_uid;
	ses->linux_uid = ctx->linux_uid;

	ses->sectype = ctx->sectype;
	ses->sign = ctx->sign;
	mutex_lock(&ses->session_mutex);

	/* add server as first channel */
	ses->chans[0].server = server;
	ses->chan_count = 1;
	ses->chan_max = ctx->multichannel ? ctx->max_channels:1;

	rc = cifs_negotiate_protocol(xid, ses);
	if (!rc)
		rc = cifs_setup_session(xid, ses, ctx->local_nls);

	/* 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 */
	spin_lock(&cifs_tcp_ses_lock);
	list_add(&ses->smb_ses_list, &server->smb_ses_list);
	spin_unlock(&cifs_tcp_ses_lock);

	free_xid(xid);

	cifs_setup_ipc(ses, ctx);

	return ses;

get_ses_fail:
	sesInfoFree(ses);
	free_xid(xid);
	return ERR_PTR(rc);
}

static int match_tcon(struct cifs_tcon *tcon, struct smb3_fs_context *ctx)
{
	if (tcon->tidStatus == CifsExiting)
		return 0;
	if (strncmp(tcon->treeName, ctx->UNC, MAX_TREE_SIZE))
		return 0;
	if (tcon->seal != ctx->seal)
		return 0;
	if (tcon->snapshot_time != ctx->snapshot_time)
		return 0;
	if (tcon->handle_timeout != ctx->handle_timeout)
		return 0;
	if (tcon->no_lease != ctx->no_lease)
		return 0;
	if (tcon->nodelete != ctx->nodelete)
		return 0;
	return 1;
}

static struct cifs_tcon *
cifs_find_tcon(struct cifs_ses *ses, struct smb3_fs_context *ctx)
{
	struct list_head *tmp;
	struct cifs_tcon *tcon;

	spin_lock(&cifs_tcp_ses_lock);
	list_for_each(tmp, &ses->tcon_list) {
		tcon = list_entry(tmp, struct cifs_tcon, tcon_list);
#ifdef CONFIG_CIFS_DFS_UPCALL
		if (tcon->dfs_path)
			continue;
#endif
		if (!match_tcon(tcon, ctx))
			continue;
		++tcon->tc_count;
		spin_unlock(&cifs_tcp_ses_lock);
		return tcon;
	}
	spin_unlock(&cifs_tcp_ses_lock);
	return NULL;
}

void
cifs_put_tcon(struct cifs_tcon *tcon)
{
	unsigned int xid;
	struct cifs_ses *ses;

	/*
	 * IPC tcon share the lifetime of their session and are
	 * destroyed in the session put function
	 */
	if (tcon == NULL || tcon->ipc)
		return;

	ses = tcon->ses;
	cifs_dbg(FYI, "%s: tc_count=%d\n", __func__, tcon->tc_count);
	spin_lock(&cifs_tcp_ses_lock);
	if (--tcon->tc_count > 0) {
		spin_unlock(&cifs_tcp_ses_lock);
		return;
	}

#ifdef CONFIG_CIFS_SWN_UPCALL
	if (tcon->use_witness) {
		int rc;

		rc = cifs_swn_unregister(tcon);
		if (rc < 0) {
			cifs_dbg(VFS, "%s: Failed to unregister for witness notifications: %d\n",
					__func__, rc);
		}
	}
#endif

	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);
	_free_xid(xid);

	cifs_fscache_release_super_cookie(tcon);
	tconInfoFree(tcon);
	cifs_put_smb_ses(ses);
}

/**
 * cifs_get_tcon - get a tcon matching @ctx data from @ses
 *
 * - tcon refcount is the number of mount points using the tcon.
 * - ses refcount is the number of tcon using the session.
 *
 * 1. This function assumes it is being called from cifs_mount() where
 *    we already got a session reference (ses refcount +1).
 *
 * 2. Since we're in the context of adding a mount point, the end
 *    result should be either:
 *
 * a) a new tcon already allocated with refcount=1 (1 mount point) and
 *    its session refcount incremented (1 new tcon). This +1 was
 *    already done in (1).
 *
 * b) an existing tcon with refcount+1 (add a mount point to it) and
 *    identical ses refcount (no new tcon). Because of (1) we need to
 *    decrement the ses refcount.
 */
static struct cifs_tcon *
cifs_get_tcon(struct cifs_ses *ses, struct smb3_fs_context *ctx)
{
	int rc, xid;
	struct cifs_tcon *tcon;

	tcon = cifs_find_tcon(ses, ctx);
	if (tcon) {
		/*
		 * tcon has refcount already incremented but we need to
		 * decrement extra ses reference gotten by caller (case b)
		 */
		cifs_dbg(FYI, "Found match on UNC path\n");
		cifs_put_smb_ses(ses);
		return tcon;
	}

	if (!ses->server->ops->tree_connect) {
		rc = -ENOSYS;
		goto out_fail;
	}

	tcon = tconInfoAlloc();
	if (tcon == NULL) {
		rc = -ENOMEM;
		goto out_fail;
	}

	if (ctx->snapshot_time) {
		if (ses->server->vals->protocol_id == 0) {
			cifs_dbg(VFS,
			     "Use SMB2 or later for snapshot mount option\n");
			rc = -EOPNOTSUPP;
			goto out_fail;
		} else
			tcon->snapshot_time = ctx->snapshot_time;
	}

	if (ctx->handle_timeout) {
		if (ses->server->vals->protocol_id == 0) {
			cifs_dbg(VFS,
			     "Use SMB2.1 or later for handle timeout option\n");
			rc = -EOPNOTSUPP;
			goto out_fail;
		} else
			tcon->handle_timeout = ctx->handle_timeout;
	}

	tcon->ses = ses;
	if (ctx->password) {
		tcon->password = kstrdup(ctx->password, GFP_KERNEL);
		if (!tcon->password) {
			rc = -ENOMEM;
			goto out_fail;
		}
	}

	if (ctx->seal) {
		if (ses->server->vals->protocol_id == 0) {
			cifs_dbg(VFS,
				 "SMB3 or later required for encryption\n");
			rc = -EOPNOTSUPP;
			goto out_fail;
		} else if (tcon->ses->server->capabilities &
					SMB2_GLOBAL_CAP_ENCRYPTION)
			tcon->seal = true;
		else {
			cifs_dbg(VFS, "Encryption is not supported on share\n");
			rc = -EOPNOTSUPP;
			goto out_fail;
		}
	}

	if (ctx->linux_ext) {
		if (ses->server->posix_ext_supported) {
			tcon->posix_extensions = true;
			pr_warn_once("SMB3.11 POSIX Extensions are experimental\n");
		} else {
			cifs_dbg(VFS, "Server does not support mounting with posix SMB3.11 extensions\n");
			rc = -EOPNOTSUPP;
			goto out_fail;
		}
	}

	/*
	 * 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);
	free_xid(xid);
	cifs_dbg(FYI, "Tcon rc = %d\n", rc);
	if (rc)
		goto out_fail;

	tcon->use_persistent = false;
	/* check if SMB2 or later, CIFS does not support persistent handles */
	if (ctx->persistent) {
		if (ses->server->vals->protocol_id == 0) {
			cifs_dbg(VFS,
			     "SMB3 or later required for persistent handles\n");
			rc = -EOPNOTSUPP;
			goto out_fail;
		} else if (ses->server->capabilities &
			   SMB2_GLOBAL_CAP_PERSISTENT_HANDLES)
			tcon->use_persistent = true;
		else /* persistent handles requested but not supported */ {
			cifs_dbg(VFS,
				"Persistent handles not supported on share\n");
			rc = -EOPNOTSUPP;
			goto out_fail;
		}
	} else if ((tcon->capabilities & SMB2_SHARE_CAP_CONTINUOUS_AVAILABILITY)
	     && (ses->server->capabilities & SMB2_GLOBAL_CAP_PERSISTENT_HANDLES)
	     && (ctx->nopersistent == false)) {
		cifs_dbg(FYI, "enabling persistent handles\n");
		tcon->use_persistent = true;
	} else if (ctx->resilient) {
		if (ses->server->vals->protocol_id == 0) {
			cifs_dbg(VFS,
			     "SMB2.1 or later required for resilient handles\n");
			rc = -EOPNOTSUPP;
			goto out_fail;
		}
		tcon->use_resilient = true;
	}
#ifdef CONFIG_CIFS_SWN_UPCALL
	tcon->use_witness = false;
	if (ctx->witness) {
		if (ses->server->vals->protocol_id >= SMB30_PROT_ID) {
			if (tcon->capabilities & SMB2_SHARE_CAP_CLUSTER) {
				/*
				 * Set witness in use flag in first place
				 * to retry registration in the echo task
				 */
				tcon->use_witness = true;
				/* And try to register immediately */
				rc = cifs_swn_register(tcon);
				if (rc < 0) {
					cifs_dbg(VFS, "Failed to register for witness notifications: %d\n", rc);
					goto out_fail;
				}
			} else {
				/* TODO: try to extend for non-cluster uses (eg multichannel) */
				cifs_dbg(VFS, "witness requested on mount but no CLUSTER capability on share\n");
				rc = -EOPNOTSUPP;
				goto out_fail;
			}
		} else {
			cifs_dbg(VFS, "SMB3 or later required for witness option\n");
			rc = -EOPNOTSUPP;
			goto out_fail;
		}
	}
#endif

	/* If the user really knows what they are doing they can override */
	if (tcon->share_flags & SMB2_SHAREFLAG_NO_CACHING) {
		if (ctx->cache_ro)
			cifs_dbg(VFS, "cache=ro requested on mount but NO_CACHING flag set on share\n");
		else if (ctx->cache_rw)
			cifs_dbg(VFS, "cache=singleclient requested on mount but NO_CACHING flag set on share\n");
	}

	if (ctx->no_lease) {
		if (ses->server->vals->protocol_id == 0) {
			cifs_dbg(VFS,
				"SMB2 or later required for nolease option\n");
			rc = -EOPNOTSUPP;
			goto out_fail;
		} else
			tcon->no_lease = ctx->no_lease;
	}

	/*
	 * We can have only one retry value for a connection to a share so for
	 * resources mounted more than once to the same server share the last
	 * value passed in for the retry flag is used.
	 */
	tcon->retry = ctx->retry;
	tcon->nocase = ctx->nocase;
	if (ses->server->capabilities & SMB2_GLOBAL_CAP_DIRECTORY_LEASING)
		tcon->nohandlecache = ctx->nohandlecache;
	else
		tcon->nohandlecache = true;
	tcon->nodelete = ctx->nodelete;
	tcon->local_lease = ctx->local_lease;
	INIT_LIST_HEAD(&tcon->pending_opens);

	spin_lock(&cifs_tcp_ses_lock);
	list_add(&tcon->tcon_list, &ses->tcon_list);
	spin_unlock(&cifs_tcp_ses_lock);

	cifs_fscache_get_super_cookie(tcon);

	return tcon;

out_fail:
	tconInfoFree(tcon);
	return ERR_PTR(rc);
}

void
cifs_put_tlink(struct tcon_link *tlink)
{
	if (!tlink || IS_ERR(tlink))
		return;

	if (!atomic_dec_and_test(&tlink->tl_count) ||
	    test_bit(TCON_LINK_IN_TREE, &tlink->tl_flags)) {
		tlink->tl_time = jiffies;
		return;
	}

	if (!IS_ERR(tlink_tcon(tlink)))
		cifs_put_tcon(tlink_tcon(tlink));
	kfree(tlink);
	return;
}

static int
compare_mount_options(struct super_block *sb, struct cifs_mnt_data *mnt_data)
{
	struct cifs_sb_info *old = CIFS_SB(sb);
	struct cifs_sb_info *new = mnt_data->cifs_sb;
	unsigned int oldflags = old->mnt_cifs_flags & CIFS_MOUNT_MASK;
	unsigned int newflags = new->mnt_cifs_flags & CIFS_MOUNT_MASK;

	if ((sb->s_flags & CIFS_MS_MASK) != (mnt_data->flags & CIFS_MS_MASK))
		return 0;

	if (old->mnt_cifs_serverino_autodisabled)
		newflags &= ~CIFS_MOUNT_SERVER_INUM;

	if (oldflags != newflags)
		return 0;

	/*
	 * We want to share sb only if we don't specify an r/wsize or
	 * specified r/wsize is greater than or equal to existing one.
	 */
	if (new->ctx->wsize && new->ctx->wsize < old->ctx->wsize)
		return 0;

	if (new->ctx->rsize && new->ctx->rsize < old->ctx->rsize)
		return 0;

	if (!uid_eq(old->ctx->linux_uid, new->ctx->linux_uid) ||
	    !gid_eq(old->ctx->linux_gid, new->ctx->linux_gid))
		return 0;

	if (old->ctx->file_mode != new->ctx->file_mode ||
	    old->ctx->dir_mode != new->ctx->dir_mode)
		return 0;

	if (strcmp(old->local_nls->charset, new->local_nls->charset))
		return 0;

	if (old->ctx->actimeo != new->ctx->actimeo)
		return 0;

	return 1;
}

static int
match_prepath(struct super_block *sb, struct cifs_mnt_data *mnt_data)
{
	struct cifs_sb_info *old = CIFS_SB(sb);
	struct cifs_sb_info *new = mnt_data->cifs_sb;
	bool old_set = (old->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH) &&
		old->prepath;
	bool new_set = (new->mnt_cifs_flags & CIFS_MOUNT_USE_PREFIX_PATH) &&
		new->prepath;

	if (old_set && new_set && !strcmp(new->prepath, old->prepath))
		return 1;
	else if (!old_set && !new_set)
		return 1;

	return 0;
}

int
cifs_match_super(struct super_block *sb, void *data)
{
	struct cifs_mnt_data *mnt_data = (struct cifs_mnt_data *)data;
	struct smb3_fs_context *ctx;
	struct cifs_sb_info *cifs_sb;
	struct TCP_Server_Info *tcp_srv;
	struct cifs_ses *ses;
	struct cifs_tcon *tcon;
	struct tcon_link *tlink;
	int rc = 0;

	spin_lock(&cifs_tcp_ses_lock);
	cifs_sb = CIFS_SB(sb);
	tlink = cifs_get_tlink(cifs_sb_master_tlink(cifs_sb));
	if (IS_ERR(tlink)) {
		spin_unlock(&cifs_tcp_ses_lock);
		return rc;
	}
	tcon = tlink_tcon(tlink);
	ses = tcon->ses;
	tcp_srv = ses->server;

	ctx = mnt_data->ctx;

	if (!match_server(tcp_srv, ctx) ||
	    !match_session(ses, ctx) ||
	    !match_tcon(tcon, ctx) ||
	    !match_prepath(sb, mnt_data)) {
		rc = 0;
		goto out;
	}

	rc = compare_mount_options(sb, mnt_data);
out:
	spin_unlock(&cifs_tcp_ses_lock);
	cifs_put_tlink(tlink);
	return rc;
}

#ifdef CONFIG_DEBUG_LOCK_ALLOC
static struct lock_class_key cifs_key[2];
static struct lock_class_key cifs_slock_key[2];

static inline void
cifs_reclassify_socket4(struct socket *sock)
{
	struct sock *sk = sock->sk;
	BUG_ON(!sock_allow_reclassification(sk));
	sock_lock_init_class_and_name(sk, "slock-AF_INET-CIFS",
		&cifs_slock_key[0], "sk_lock-AF_INET-CIFS", &cifs_key[0]);
}

static inline void
cifs_reclassify_socket6(struct socket *sock)
{
	struct sock *sk = sock->sk;
	BUG_ON(!sock_allow_reclassification(sk));
	sock_lock_init_class_and_name(sk, "slock-AF_INET6-CIFS",
		&cifs_slock_key[1], "sk_lock-AF_INET6-CIFS", &cifs_key[1]);
}
#else
static inline void
cifs_reclassify_socket4(struct socket *sock)
{
}

static inline void
cifs_reclassify_socket6(struct socket *sock)
{
}
#endif

/* See RFC1001 section 14 on representation of Netbios names */
static void rfc1002mangle(char *target, char *source, unsigned int length)
{
	unsigned int i, j;

	for (i = 0, j = 0; i < (length); i++) {
		/* mask a nibble at a time and encode */
		target[j] = 'A' + (0x0F & (source[i] >> 4));
		target[j+1] = 'A' + (0x0F & source[i]);
		j += 2;
	}

}

static int
bind_socket(struct TCP_Server_Info *server)
{
	int rc = 0;
	if (server->srcaddr.ss_family != AF_UNSPEC) {
		/* Bind to the specified local IP address */
		struct socket *socket = server->ssocket;
		rc = socket->ops->bind(socket,
				       (struct sockaddr *) &server->srcaddr,
				       sizeof(server->srcaddr));
		if (rc < 0) {
			struct sockaddr_in *saddr4;
			struct sockaddr_in6 *saddr6;
			saddr4 = (struct sockaddr_in *)&server->srcaddr;
			saddr6 = (struct sockaddr_in6 *)&server->srcaddr;
			if (saddr6->sin6_family == AF_INET6)
				cifs_server_dbg(VFS, "Failed to bind to: %pI6c, error: %d\n",
					 &saddr6->sin6_addr, rc);
			else
				cifs_server_dbg(VFS, "Failed to bind to: %pI4, error: %d\n",
					 &saddr4->sin_addr.s_addr, rc);
		}
	}
	return rc;
}

static int
ip_rfc1001_connect(struct TCP_Server_Info *server)
{
	int rc = 0;
	/*
	 * some servers require RFC1001 sessinit before sending
	 * negprot - BB check reconnection in case where second
	 * sessinit is sent but no second negprot
	 */
	struct rfc1002_session_packet *ses_init_buf;
	struct smb_hdr *smb_buf;
	ses_init_buf = kzalloc(sizeof(struct rfc1002_session_packet),
			       GFP_KERNEL);
	if (ses_init_buf) {
		ses_init_buf->trailer.session_req.called_len = 32;

		if (server->server_RFC1001_name[0] != 0)
			rfc1002mangle(ses_init_buf->trailer.
				      session_req.called_name,
				      server->server_RFC1001_name,
				      RFC1001_NAME_LEN_WITH_NULL);
		else
			rfc1002mangle(ses_init_buf->trailer.
				      session_req.called_name,
				      DEFAULT_CIFS_CALLED_NAME,
				      RFC1001_NAME_LEN_WITH_NULL);

		ses_init_buf->trailer.session_req.calling_len = 32;

		/*
		 * calling name ends in null (byte 16) from old smb
		 * convention.
		 */
		if (server->workstation_RFC1001_name[0] != 0)
			rfc1002mangle(ses_init_buf->trailer.
				      session_req.calling_name,
				      server->workstation_RFC1001_name,
				      RFC1001_NAME_LEN_WITH_NULL);
		else
			rfc1002mangle(ses_init_buf->trailer.
				      session_req.calling_name,
				      "LINUX_CIFS_CLNT",
				      RFC1001_NAME_LEN_WITH_NULL);

		ses_init_buf->trailer.session_req.scope1 = 0;
		ses_init_buf->trailer.session_req.scope2 = 0;
		smb_buf = (struct smb_hdr *)ses_init_buf;

		/* sizeof RFC1002_SESSION_REQUEST with no scope */
		smb_buf->smb_buf_length = cpu_to_be32(0x81000044);
		rc = smb_send(server, smb_buf, 0x44);
		kfree(ses_init_buf);
		/*
		 * RFC1001 layer in at least one server
		 * requires very short break before negprot
		 * presumably because not expecting negprot
		 * to follow so fast.  This is a simple
		 * solution that works without
		 * complicating the code and causes no
		 * significant slowing down on mount
		 * for everyone else
		 */
		usleep_range(1000, 2000);
	}
	/*
	 * else the negprot may still work without this
	 * even though malloc failed
	 */

	return rc;
}

static int
generic_ip_connect(struct TCP_Server_Info *server)
{
	int rc = 0;
	__be16 sport;
	int slen, sfamily;
	struct socket *socket = server->ssocket;
	struct sockaddr *saddr;

	saddr = (struct sockaddr *) &server->dstaddr;

	if (server->dstaddr.ss_family == AF_INET6) {
		struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)&server->dstaddr;

		sport = ipv6->sin6_port;
		slen = sizeof(struct sockaddr_in6);
		sfamily = AF_INET6;
		cifs_dbg(FYI, "%s: connecting to [%pI6]:%d\n", __func__, &ipv6->sin6_addr,
				ntohs(sport));
	} else {
		struct sockaddr_in *ipv4 = (struct sockaddr_in *)&server->dstaddr;

		sport = ipv4->sin_port;
		slen = sizeof(struct sockaddr_in);
		sfamily = AF_INET;
		cifs_dbg(FYI, "%s: connecting to %pI4:%d\n", __func__, &ipv4->sin_addr,
				ntohs(sport));
	}

	if (socket == NULL) {
		rc = __sock_create(cifs_net_ns(server), sfamily, SOCK_STREAM,
				   IPPROTO_TCP, &socket, 1);
		if (rc < 0) {
			cifs_server_dbg(VFS, "Error %d creating socket\n", rc);
			server->ssocket = NULL;
			return rc;
		}

		/* BB other socket options to set KEEPALIVE, NODELAY? */
		cifs_dbg(FYI, "Socket created\n");
		server->ssocket = socket;
		socket->sk->sk_allocation = GFP_NOFS;
		if (sfamily == AF_INET6)
			cifs_reclassify_socket6(socket);
		else
			cifs_reclassify_socket4(socket);
	}

	rc = bind_socket(server);
	if (rc < 0)
		return rc;

	/*
	 * Eventually check for other socket options to change from
	 * the default. sock_setsockopt not used because it expects
	 * user space buffer
	 */
	socket->sk->sk_rcvtimeo = 7 * HZ;
	socket->sk->sk_sndtimeo = 5 * HZ;

	/* make the bufsizes depend on wsize/rsize and max requests */
	if (server->noautotune) {
		if (socket->sk->sk_sndbuf < (200 * 1024))
			socket->sk->sk_sndbuf = 200 * 1024;
		if (socket->sk->sk_rcvbuf < (140 * 1024))
			socket->sk->sk_rcvbuf = 140 * 1024;
	}

	if (server->tcp_nodelay)
		tcp_sock_set_nodelay(socket->sk);

	cifs_dbg(FYI, "sndbuf %d rcvbuf %d rcvtimeo 0x%lx\n",
		 socket->sk->sk_sndbuf,
		 socket->sk->sk_rcvbuf, socket->sk->sk_rcvtimeo);

	rc = socket->ops->connect(socket, saddr, slen,
				  server->noblockcnt ? O_NONBLOCK : 0);
	/*
	 * When mounting SMB root file systems, we do not want to block in
	 * connect. Otherwise bail out and then let cifs_reconnect() perform
	 * reconnect failover - if possible.
	 */
	if (server->noblockcnt && rc == -EINPROGRESS)
		rc = 0;
	if (rc < 0) {
		cifs_dbg(FYI, "Error %d connecting to server\n", rc);
		sock_release(socket);
		server->ssocket = NULL;
		return rc;
	}

	if (sport == htons(RFC1001_PORT))
		rc = ip_rfc1001_connect(server);

	return rc;
}

static int
ip_connect(struct TCP_Server_Info *server)
{
	__be16 *sport;
	struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&server->dstaddr;
	struct sockaddr_in *addr = (struct sockaddr_in *)&server->dstaddr;

	if (server->dstaddr.ss_family == AF_INET6)
		sport = &addr6->sin6_port;
	else
		sport = &addr->sin_port;

	if (*sport == 0) {
		int rc;

		/* try with 445 port at first */
		*sport = htons(CIFS_PORT);

		rc = generic_ip_connect(server);
		if (rc >= 0)
			return rc;

		/* if it failed, try with 139 port */
		*sport = htons(RFC1001_PORT);
	}

	return generic_ip_connect(server);
}

void reset_cifs_unix_caps(unsigned int xid, struct cifs_tcon *tcon,
			  struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx)
{
	/*
	 * If we are reconnecting then should we check to see if
	 * any requested capabilities changed locally e.g. via
	 * remount but we can not do much about it here
	 * if they have (even if we could detect it by the following)
	 * Perhaps we could add a backpointer to array of sb from tcon
	 * or if we change to make all sb to same share the same
	 * sb as NFS - then we only have one backpointer to sb.
	 * What if we wanted to mount the server share twice once with
	 * and once without posixacls or posix paths?
	 */
	__u64 saved_cap = le64_to_cpu(tcon->fsUnixInfo.Capability);

	if (ctx && ctx->no_linux_ext) {
		tcon->fsUnixInfo.Capability = 0;
		tcon->unix_ext = 0; /* Unix Extensions disabled */
		cifs_dbg(FYI, "Linux protocol extensions disabled\n");
		return;
	} else if (ctx)
		tcon->unix_ext = 1; /* Unix Extensions supported */

	if (!tcon->unix_ext) {
		cifs_dbg(FYI, "Unix extensions disabled so not set on reconnect\n");
		return;
	}

	if (!CIFSSMBQFSUnixInfo(xid, tcon)) {
		__u64 cap = le64_to_cpu(tcon->fsUnixInfo.Capability);
		cifs_dbg(FYI, "unix caps which server supports %lld\n", cap);
		/*
		 * check for reconnect case in which we do not
		 * want to change the mount behavior if we can avoid it
		 */
		if (ctx == NULL) {
			/*
			 * turn off POSIX ACL and PATHNAMES if not set
			 * originally at mount time
			 */
			if ((saved_cap & CIFS_UNIX_POSIX_ACL_CAP) == 0)
				cap &= ~CIFS_UNIX_POSIX_ACL_CAP;
			if ((saved_cap & CIFS_UNIX_POSIX_PATHNAMES_CAP) == 0) {
				if (cap & CIFS_UNIX_POSIX_PATHNAMES_CAP)
					cifs_dbg(VFS, "POSIXPATH support change\n");
				cap &= ~CIFS_UNIX_POSIX_PATHNAMES_CAP;
			} else if ((cap & CIFS_UNIX_POSIX_PATHNAMES_CAP) == 0) {
				cifs_dbg(VFS, "possible reconnect error\n");
				cifs_dbg(VFS, "server disabled POSIX path support\n");
			}
		}

		if (cap & CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP)
			cifs_dbg(VFS, "per-share encryption not supported yet\n");

		cap &= CIFS_UNIX_CAP_MASK;
		if (ctx && ctx->no_psx_acl)
			cap &= ~CIFS_UNIX_POSIX_ACL_CAP;
		else if (CIFS_UNIX_POSIX_ACL_CAP & cap) {
			cifs_dbg(FYI, "negotiated posix acl support\n");
			if (cifs_sb)
				cifs_sb->mnt_cifs_flags |=
					CIFS_MOUNT_POSIXACL;
		}

		if (ctx && ctx->posix_paths == 0)
			cap &= ~CIFS_UNIX_POSIX_PATHNAMES_CAP;
		else if (cap & CIFS_UNIX_POSIX_PATHNAMES_CAP) {
			cifs_dbg(FYI, "negotiate posix pathnames\n");
			if (cifs_sb)
				cifs_sb->mnt_cifs_flags |=
					CIFS_MOUNT_POSIX_PATHS;
		}

		cifs_dbg(FYI, "Negotiate caps 0x%x\n", (int)cap);
#ifdef CONFIG_CIFS_DEBUG2
		if (cap & CIFS_UNIX_FCNTL_CAP)
			cifs_dbg(FYI, "FCNTL cap\n");
		if (cap & CIFS_UNIX_EXTATTR_CAP)
			cifs_dbg(FYI, "EXTATTR cap\n");
		if (cap & CIFS_UNIX_POSIX_PATHNAMES_CAP)
			cifs_dbg(FYI, "POSIX path cap\n");
		if (cap & CIFS_UNIX_XATTR_CAP)
			cifs_dbg(FYI, "XATTR cap\n");
		if (cap & CIFS_UNIX_POSIX_ACL_CAP)
			cifs_dbg(FYI, "POSIX ACL cap\n");
		if (cap & CIFS_UNIX_LARGE_READ_CAP)
			cifs_dbg(FYI, "very large read cap\n");
		if (cap & CIFS_UNIX_LARGE_WRITE_CAP)
			cifs_dbg(FYI, "very large write cap\n");
		if (cap & CIFS_UNIX_TRANSPORT_ENCRYPTION_CAP)
			cifs_dbg(FYI, "transport encryption cap\n");
		if (cap & CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP)
			cifs_dbg(FYI, "mandatory transport encryption cap\n");
#endif /* CIFS_DEBUG2 */
		if (CIFSSMBSetFSUnixInfo(xid, tcon, cap)) {
			if (ctx == NULL)
				cifs_dbg(FYI, "resetting capabilities failed\n");
			else
				cifs_dbg(VFS, "Negotiating Unix capabilities with the server failed. Consider mounting with the Unix Extensions disabled if problems are found by specifying the nounix mount option.\n");

		}
	}
}

int cifs_setup_cifs_sb(struct cifs_sb_info *cifs_sb)
{
	struct smb3_fs_context *ctx = cifs_sb->ctx;

	INIT_DELAYED_WORK(&cifs_sb->prune_tlinks, cifs_prune_tlinks);

	spin_lock_init(&cifs_sb->tlink_tree_lock);
	cifs_sb->tlink_tree = RB_ROOT;

	cifs_dbg(FYI, "file mode: %04ho  dir mode: %04ho\n",
		 ctx->file_mode, ctx->dir_mode);

	/* this is needed for ASCII cp to Unicode converts */
	if (ctx->iocharset == NULL) {
		/* load_nls_default cannot return null */
		cifs_sb->local_nls = load_nls_default();
	} else {
		cifs_sb->local_nls = load_nls(ctx->iocharset);
		if (cifs_sb->local_nls == NULL) {
			cifs_dbg(VFS, "CIFS mount error: iocharset %s not found\n",
				 ctx->iocharset);
			return -ELIBACC;
		}
	}
	ctx->local_nls = cifs_sb->local_nls;

	smb3_update_mnt_flags(cifs_sb);

	if (ctx->direct_io)
		cifs_dbg(FYI, "mounting share using direct i/o\n");
	if (ctx->cache_ro) {
		cifs_dbg(VFS, "mounting share with read only caching. Ensure that the share will not be modified while in use.\n");
		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_RO_CACHE;
	} else if (ctx->cache_rw) {
		cifs_dbg(VFS, "mounting share in single client RW caching mode. Ensure that no other systems will be accessing the share.\n");
		cifs_sb->mnt_cifs_flags |= (CIFS_MOUNT_RO_CACHE |
					    CIFS_MOUNT_RW_CACHE);
	}

	if ((ctx->cifs_acl) && (ctx->dynperm))
		cifs_dbg(VFS, "mount option dynperm ignored if cifsacl mount option supported\n");

	if (ctx->prepath) {
		cifs_sb->prepath = kstrdup(ctx->prepath, GFP_KERNEL);
		if (cifs_sb->prepath == NULL)
			return -ENOMEM;
		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
	}

	return 0;
}

/* Release all succeed connections */
static inline void mount_put_conns(struct cifs_sb_info *cifs_sb,
				   unsigned int xid,
				   struct TCP_Server_Info *server,
				   struct cifs_ses *ses, struct cifs_tcon *tcon)
{
	int rc = 0;

	if (tcon)
		cifs_put_tcon(tcon);
	else if (ses)
		cifs_put_smb_ses(ses);
	else if (server)
		cifs_put_tcp_session(server, 0);
	cifs_sb->mnt_cifs_flags &= ~CIFS_MOUNT_POSIX_PATHS;
	free_xid(xid);
}

/* Get connections for tcp, ses and tcon */
static int mount_get_conns(struct smb3_fs_context *ctx, struct cifs_sb_info *cifs_sb,
			   unsigned int *xid,
			   struct TCP_Server_Info **nserver,
			   struct cifs_ses **nses, struct cifs_tcon **ntcon)
{
	int rc = 0;
	struct TCP_Server_Info *server;
	struct cifs_ses *ses;
	struct cifs_tcon *tcon;

	*nserver = NULL;
	*nses = NULL;
	*ntcon = NULL;

	*xid = get_xid();

	/* get a reference to a tcp session */
	server = cifs_get_tcp_session(ctx);
	if (IS_ERR(server)) {
		rc = PTR_ERR(server);
		return rc;
	}

	*nserver = server;

	if ((ctx->max_credits < 20) || (ctx->max_credits > 60000))
		server->max_credits = SMB2_MAX_CREDITS_AVAILABLE;
	else
		server->max_credits = ctx->max_credits;

	/* get a reference to a SMB session */
	ses = cifs_get_smb_ses(server, ctx);
	if (IS_ERR(ses)) {
		rc = PTR_ERR(ses);
		return rc;
	}

	*nses = ses;

	if ((ctx->persistent == true) && (!(ses->server->capabilities &
					    SMB2_GLOBAL_CAP_PERSISTENT_HANDLES))) {
		cifs_server_dbg(VFS, "persistent handles not supported by server\n");
		return -EOPNOTSUPP;
	}

	/* search for existing tcon to this server share */
	tcon = cifs_get_tcon(ses, ctx);
	if (IS_ERR(tcon)) {
		rc = PTR_ERR(tcon);
		return rc;
	}

	*ntcon = tcon;

	/* if new SMB3.11 POSIX extensions are supported do not remap / and \ */
	if (tcon->posix_extensions)
		cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_POSIX_PATHS;

	/* tell server which Unix caps we support */
	if (cap_unix(tcon->ses)) {
		/*
		 * reset of caps checks mount to see if unix extensions disabled
		 * for just this mount.
		 */
		reset_cifs_unix_caps(*xid, tcon, cifs_sb, ctx);
		if ((tcon->ses->server->tcpStatus == CifsNeedReconnect) &&
		    (le64_to_cpu(tcon->fsUnixInfo.Capability) &
		     CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP))
			return -EACCES;
	} else
		tcon->unix_ext = 0; /* server does not support them */

	/* do not care if a following call succeed - informational */
	if (!tcon->pipe && server->ops->qfs_tcon) {
		server->ops->qfs_tcon(*xid, tcon, cifs_sb);
		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RO_CACHE) {
			if (tcon->fsDevInfo.DeviceCharacteristics &
			    cpu_to_le32(FILE_READ_ONLY_DEVICE))
				cifs_dbg(VFS, "mounted to read only share\n");
			else if ((cifs_sb->mnt_cifs_flags &
				  CIFS_MOUNT_RW_CACHE) == 0)
				cifs_dbg(VFS, "read only mount of RW share\n");
			/* no need to log a RW mount of a typical RW share */
		}
	}

	/*
	 * Clamp the rsize/wsize mount arguments if they are too big for the server
	 * and set the rsize/wsize to the negotiated values if not passed in by
	 * the user on mount
	 */
	if ((cifs_sb->ctx->wsize == 0) ||
	    (cifs_sb->ctx->wsize > server->ops->negotiate_wsize(tcon, ctx)))
		cifs_sb->ctx->wsize = server->ops->negotiate_wsize(tcon, ctx);
	if ((cifs_sb->ctx->rsize == 0) ||
	    (cifs_sb->ctx->rsize > server->ops->negotiate_rsize(tcon, ctx)))
		cifs_sb->ctx->rsize = server->ops->negotiate_rsize(tcon, ctx);

	return 0;
}

static int mount_setup_tlink(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
			     struct cifs_tcon *tcon)
{
	struct tcon_link *tlink;

	/* hang the tcon off of the superblock */
	tlink = kzalloc(sizeof(*tlink), GFP_KERNEL);
	if (tlink == NULL)
		return -ENOMEM;

	tlink->tl_uid = ses->linux_uid;
	tlink->tl_tcon = tcon;
	tlink->tl_time = jiffies;
	set_bit(TCON_LINK_MASTER, &tlink->tl_flags);
	set_bit(TCON_LINK_IN_TREE, &tlink->tl_flags);

	cifs_sb->master_tlink = tlink;
	spin_lock(&cifs_sb->tlink_tree_lock);
	tlink_rb_insert(&cifs_sb->tlink_tree, tlink);
	spin_unlock(&cifs_sb->tlink_tree_lock);

	queue_delayed_work(cifsiod_wq, &cifs_sb->prune_tlinks,
				TLINK_IDLE_EXPIRE);
	return 0;
}

#ifdef CONFIG_CIFS_DFS_UPCALL
/*
 * cifs_build_path_to_root returns full path to root when we do not have an
 * existing connection (tcon)
 */
static char *
build_unc_path_to_root(const struct smb3_fs_context *ctx,
		       const struct cifs_sb_info *cifs_sb, bool useppath)
{
	char *full_path, *pos;
	unsigned int pplen = useppath && ctx->prepath ?
		strlen(ctx->prepath) + 1 : 0;
	unsigned int unc_len = strnlen(ctx->UNC, MAX_TREE_SIZE + 1);

	if (unc_len > MAX_TREE_SIZE)
		return ERR_PTR(-EINVAL);

	full_path = kmalloc(unc_len + pplen + 1, GFP_KERNEL);
	if (full_path == NULL)
		return ERR_PTR(-ENOMEM);

	memcpy(full_path, ctx->UNC, unc_len);
	pos = full_path + unc_len;

	if (pplen) {
		*pos = CIFS_DIR_SEP(cifs_sb);
		memcpy(pos + 1, ctx->prepath, pplen);
		pos += pplen;
	}

	*pos = '\0'; /* add trailing null */
	convert_delimiter(full_path, CIFS_DIR_SEP(cifs_sb));
	cifs_dbg(FYI, "%s: full_path=%s\n", __func__, full_path);
	return full_path;
}

/**
 * expand_dfs_referral - Perform a dfs referral query and update the cifs_sb
 *
 * If a referral is found, cifs_sb->ctx->mount_options will be (re-)allocated
 * to a string containing updated options for the submount.  Otherwise it
 * will be left untouched.
 *
 * Returns the rc from get_dfs_path to the caller, which can be used to
 * determine whether there were referrals.
 */
static int
expand_dfs_referral(const unsigned int xid, struct cifs_ses *ses,
		    struct smb3_fs_context *ctx, struct cifs_sb_info *cifs_sb,
		    char *ref_path)
{
	int rc;
	struct dfs_info3_param referral = {0};
	char *full_path = NULL, *mdata = NULL;

	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS)
		return -EREMOTE;

	full_path = build_unc_path_to_root(ctx, cifs_sb, true);
	if (IS_ERR(full_path))
		return PTR_ERR(full_path);

	rc = dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb),
			    ref_path, &referral, NULL);
	if (!rc) {
		char *fake_devname = NULL;

		mdata = cifs_compose_mount_options(cifs_sb->ctx->mount_options,
						   full_path + 1, &referral,
						   &fake_devname);
		free_dfs_info_param(&referral);

		if (IS_ERR(mdata)) {
			rc = PTR_ERR(mdata);
			mdata = NULL;
		} else {
			/*
			 * We can not clear out the whole structure since we
			 * no longer have an explicit function to parse
			 * a mount-string. Instead we need to clear out the
			 * individual fields that are no longer valid.
			 */
			kfree(ctx->prepath);
			ctx->prepath = NULL;
			rc = cifs_setup_volume_info(ctx, mdata, fake_devname);
		}
		kfree(fake_devname);
		kfree(cifs_sb->ctx->mount_options);
		cifs_sb->ctx->mount_options = mdata;
	}
	kfree(full_path);
	return rc;
}

static inline int get_next_dfs_tgt(const char *path,
				   struct dfs_cache_tgt_list *tgt_list,
				   struct dfs_cache_tgt_iterator **tgt_it)
{
	if (!*tgt_it)
		*tgt_it = dfs_cache_get_tgt_iterator(tgt_list);
	else
		*tgt_it = dfs_cache_get_next_tgt(tgt_list, *tgt_it);
	return !*tgt_it ? -EHOSTDOWN : 0;
}

static int update_vol_info(const struct dfs_cache_tgt_iterator *tgt_it,
			   struct smb3_fs_context *fake_ctx, struct smb3_fs_context *ctx)
{
	const char *tgt = dfs_cache_get_tgt_name(tgt_it);
	int len = strlen(tgt) + 2;
	char *new_unc;

	new_unc = kmalloc(len, GFP_KERNEL);
	if (!new_unc)
		return -ENOMEM;
	scnprintf(new_unc, len, "\\%s", tgt);

	kfree(ctx->UNC);
	ctx->UNC = new_unc;

	if (fake_ctx->prepath) {
		kfree(ctx->prepath);
		ctx->prepath = fake_ctx->prepath;
		fake_ctx->prepath = NULL;
	}
	memcpy(&ctx->dstaddr, &fake_ctx->dstaddr, sizeof(ctx->dstaddr));

	return 0;
}

static int setup_dfs_tgt_conn(const char *path, const char *full_path,
			      const struct dfs_cache_tgt_iterator *tgt_it,
			      struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx,
			      unsigned int *xid, struct TCP_Server_Info **server,
			      struct cifs_ses **ses, struct cifs_tcon **tcon)
{
	int rc;
	struct dfs_info3_param ref = {0};
	char *mdata = NULL;
	struct smb3_fs_context fake_ctx = {NULL};
	char *fake_devname = NULL;

	cifs_dbg(FYI, "%s: dfs path: %s\n", __func__, path);

	rc = dfs_cache_get_tgt_referral(path, tgt_it, &ref);
	if (rc)
		return rc;

	mdata = cifs_compose_mount_options(cifs_sb->ctx->mount_options,
					   full_path + 1, &ref,
					   &fake_devname);
	free_dfs_info_param(&ref);

	if (IS_ERR(mdata)) {
		rc = PTR_ERR(mdata);
		mdata = NULL;
	} else
		rc = cifs_setup_volume_info(&fake_ctx, mdata, fake_devname);

	kfree(mdata);
	kfree(fake_devname);

	if (!rc) {
		/*
		 * We use a 'fake_ctx' here because we need pass it down to the
		 * mount_{get,put} functions to test connection against new DFS
		 * targets.
		 */
		mount_put_conns(cifs_sb, *xid, *server, *ses, *tcon);
		rc = mount_get_conns(&fake_ctx, cifs_sb, xid, server, ses,
				     tcon);
		if (!rc || (*server && *ses)) {
			/*
			 * We were able to connect to new target server.
			 * Update current context with new target server.
			 */
			rc = update_vol_info(tgt_it, &fake_ctx, ctx);
		}
	}
	smb3_cleanup_fs_context_contents(&fake_ctx);
	return rc;
}

static int do_dfs_failover(const char *path, const char *full_path, struct cifs_sb_info *cifs_sb,
			   struct smb3_fs_context *ctx, struct cifs_ses *root_ses,
			   unsigned int *xid, struct TCP_Server_Info **server,
			   struct cifs_ses **ses, struct cifs_tcon **tcon)
{
	int rc;
	struct dfs_cache_tgt_list tgt_list;
	struct dfs_cache_tgt_iterator *tgt_it = NULL;

	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS)
		return -EOPNOTSUPP;

	rc = dfs_cache_noreq_find(path, NULL, &tgt_list);
	if (rc)
		return rc;

	for (;;) {
		/* Get next DFS target server - if any */
		rc = get_next_dfs_tgt(path, &tgt_list, &tgt_it);
		if (rc)
			break;
		/* Connect to next DFS target */
		rc = setup_dfs_tgt_conn(path, full_path, tgt_it, cifs_sb, ctx, xid, server, ses,
					tcon);
		if (!rc || (*server && *ses))
			break;
	}
	if (!rc) {
		/*
		 * Update DFS target hint in DFS referral cache with the target
		 * server we successfully reconnected to.
		 */
		rc = dfs_cache_update_tgthint(*xid, root_ses ? root_ses : *ses,
					      cifs_sb->local_nls,
					      cifs_remap(cifs_sb), path,
					      tgt_it);
	}
	dfs_cache_free_tgts(&tgt_list);
	return rc;
}
#endif

/* TODO: all callers to this are broken. We are not parsing mount_options here
 * we should pass a clone of the original context?
 */
int
cifs_setup_volume_info(struct smb3_fs_context *ctx, const char *mntopts, const char *devname)
{
	int rc = 0;

	smb3_parse_devname(devname, ctx);

	if (mntopts) {
		char *ip;

		cifs_dbg(FYI, "%s: mntopts=%s\n", __func__, mntopts);
		rc = smb3_parse_opt(mntopts, "ip", &ip);
		if (!rc && !cifs_convert_address((struct sockaddr *)&ctx->dstaddr, ip,
						 strlen(ip))) {
			cifs_dbg(VFS, "%s: failed to convert ip address\n", __func__);
			return -EINVAL;
		}
	}

	if (ctx->nullauth) {
		cifs_dbg(FYI, "Anonymous login\n");
		kfree(ctx->username);
		ctx->username = NULL;
	} else if (ctx->username) {
		/* BB fixme parse for domain name here */
		cifs_dbg(FYI, "Username: %s\n", ctx->username);
	} else {
		cifs_dbg(VFS, "No username specified\n");
	/* In userspace mount helper we can get user name from alternate
	   locations such as env variables and files on disk */
		return -EINVAL;
	}

	return rc;
}

static int
cifs_are_all_path_components_accessible(struct TCP_Server_Info *server,
					unsigned int xid,
					struct cifs_tcon *tcon,
					struct cifs_sb_info *cifs_sb,
					char *full_path,
					int added_treename)
{
	int rc;
	char *s;
	char sep, tmp;
	int skip = added_treename ? 1 : 0;

	sep = CIFS_DIR_SEP(cifs_sb);
	s = full_path;

	rc = server->ops->is_path_accessible(xid, tcon, cifs_sb, "");
	while (rc == 0) {
		/* skip separators */
		while (*s == sep)
			s++;
		if (!*s)
			break;
		/* next separator */
		while (*s && *s != sep)
			s++;
		/*
		 * if the treename is added, we then have to skip the first
		 * part within the separators
		 */
		if (skip) {
			skip = 0;
			continue;
		}
		/*
		 * temporarily null-terminate the path at the end of
		 * the current component
		 */
		tmp = *s;
		*s = 0;
		rc = server->ops->is_path_accessible(xid, tcon, cifs_sb,
						     full_path);
		*s = tmp;
	}
	return rc;
}

/*
 * Check if path is remote (e.g. a DFS share). Return -EREMOTE if it is,
 * otherwise 0.
 */
static int is_path_remote(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx,
			  const unsigned int xid,
			  struct TCP_Server_Info *server,
			  struct cifs_tcon *tcon)
{
	int rc;
	char *full_path;

	if (!server->ops->is_path_accessible)
		return -EOPNOTSUPP;

	/*
	 * cifs_build_path_to_root works only when we have a valid tcon
	 */
	full_path = cifs_build_path_to_root(ctx, cifs_sb, tcon,
					    tcon->Flags & SMB_SHARE_IS_IN_DFS);
	if (full_path == NULL)
		return -ENOMEM;

	cifs_dbg(FYI, "%s: full_path: %s\n", __func__, full_path);

	rc = server->ops->is_path_accessible(xid, tcon, cifs_sb,
					     full_path);
	if (rc != 0 && rc != -EREMOTE) {
		kfree(full_path);
		return rc;
	}

	if (rc != -EREMOTE) {
		rc = cifs_are_all_path_components_accessible(server, xid, tcon,
			cifs_sb, full_path, tcon->Flags & SMB_SHARE_IS_IN_DFS);
		if (rc != 0) {
			cifs_server_dbg(VFS, "cannot query dirs between root and final path, enabling CIFS_MOUNT_USE_PREFIX_PATH\n");
			cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
			rc = 0;
		}
	}

	kfree(full_path);
	return rc;
}

#ifdef CONFIG_CIFS_DFS_UPCALL
static void set_root_ses(struct cifs_sb_info *cifs_sb, struct cifs_ses *ses,
			 struct cifs_ses **root_ses)
{
	if (ses) {
		spin_lock(&cifs_tcp_ses_lock);
		ses->ses_count++;
		if (ses->tcon_ipc)
			ses->tcon_ipc->remap = cifs_remap(cifs_sb);
		spin_unlock(&cifs_tcp_ses_lock);
	}
	*root_ses = ses;
}

static void put_root_ses(struct cifs_ses *ses)
{
	if (ses)
		cifs_put_smb_ses(ses);
}

/* Check if a path component is remote and then update @dfs_path accordingly */
static int check_dfs_prepath(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx,
			     const unsigned int xid, struct TCP_Server_Info *server,
			     struct cifs_tcon *tcon, char **dfs_path)
{
	char *path, *s;
	char sep = CIFS_DIR_SEP(cifs_sb), tmp;
	char *npath;
	int rc = 0;
	int added_treename = tcon->Flags & SMB_SHARE_IS_IN_DFS;
	int skip = added_treename;

	path = cifs_build_path_to_root(ctx, cifs_sb, tcon, added_treename);
	if (!path)
		return -ENOMEM;

	/*
	 * Walk through the path components in @path and check if they're accessible. In case any of
	 * the components is -EREMOTE, then update @dfs_path with the next DFS referral request path
	 * (NOT including the remaining components).
	 */
	s = path;
	do {
		/* skip separators */
		while (*s && *s == sep)
			s++;
		if (!*s)
			break;
		/* next separator */
		while (*s && *s != sep)
			s++;
		/*
		 * if the treename is added, we then have to skip the first
		 * part within the separators
		 */
		if (skip) {
			skip = 0;
			continue;
		}
		tmp = *s;
		*s = 0;
		rc = server->ops->is_path_accessible(xid, tcon, cifs_sb, path);
		if (rc && rc == -EREMOTE) {
			struct smb3_fs_context v = {NULL};
			/* if @path contains a tree name, skip it in the prefix path */
			if (added_treename) {
				rc = smb3_parse_devname(path, &v);
				if (rc)
					break;
				rc = -EREMOTE;
				npath = build_unc_path_to_root(&v, cifs_sb, true);
				smb3_cleanup_fs_context_contents(&v);
			} else {
				v.UNC = ctx->UNC;
				v.prepath = path + 1;
				npath = build_unc_path_to_root(&v, cifs_sb, true);
			}
			if (IS_ERR(npath)) {
				rc = PTR_ERR(npath);
				break;
			}
			kfree(*dfs_path);
			*dfs_path = npath;
		}
		*s = tmp;
	} while (rc == 0);

	kfree(path);
	return rc;
}

int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx)
{
	int rc = 0;
	unsigned int xid;
	struct TCP_Server_Info *server = NULL;
	struct cifs_ses *ses = NULL, *root_ses = NULL;
	struct cifs_tcon *tcon = NULL;
	int count = 0;
	char *ref_path = NULL, *full_path = NULL;
	char *oldmnt = NULL;
	char *mntdata = NULL;

	rc = mount_get_conns(ctx, cifs_sb, &xid, &server, &ses, &tcon);
	/*
	 * Unconditionally try to get an DFS referral (even cached) to determine whether it is an
	 * DFS mount.
	 *
	 * Skip prefix path to provide support for DFS referrals from w2k8 servers which don't seem
	 * to respond with PATH_NOT_COVERED to requests that include the prefix.
	 */
	if (dfs_cache_find(xid, ses, cifs_sb->local_nls, cifs_remap(cifs_sb), ctx->UNC + 1, NULL,
			   NULL)) {
		/* No DFS referral was returned.  Looks like a regular share. */
		if (rc)
			goto error;
		/* Check if it is fully accessible and then mount it */
		rc = is_path_remote(cifs_sb, ctx, xid, server, tcon);
		if (!rc)
			goto out;
		if (rc != -EREMOTE)
			goto error;
	}
	/* Save mount options */
	mntdata = kstrndup(cifs_sb->ctx->mount_options,
			   strlen(cifs_sb->ctx->mount_options), GFP_KERNEL);
	if (!mntdata) {
		rc = -ENOMEM;
		goto error;
	}
	/* Get path of DFS root */
	ref_path = build_unc_path_to_root(ctx, cifs_sb, false);
	if (IS_ERR(ref_path)) {
		rc = PTR_ERR(ref_path);
		ref_path = NULL;
		goto error;
	}

	set_root_ses(cifs_sb, ses, &root_ses);
	do {
		/* Save full path of last DFS path we used to resolve final target server */
		kfree(full_path);
		full_path = build_unc_path_to_root(ctx, cifs_sb, !!count);
		if (IS_ERR(full_path)) {
			rc = PTR_ERR(full_path);
			full_path = NULL;
			break;
		}
		/* Chase referral */
		oldmnt = cifs_sb->ctx->mount_options;
		rc = expand_dfs_referral(xid, root_ses, ctx, cifs_sb, ref_path + 1);
		if (rc)
			break;
		/* Connect to new DFS target only if we were redirected */
		if (oldmnt != cifs_sb->ctx->mount_options) {
			mount_put_conns(cifs_sb, xid, server, ses, tcon);
			rc = mount_get_conns(ctx, cifs_sb, &xid, &server, &ses, &tcon);
		}
		if (rc && !server && !ses) {
			/* Failed to connect. Try to connect to other targets in the referral. */
			rc = do_dfs_failover(ref_path + 1, full_path, cifs_sb, ctx, root_ses, &xid,
					     &server, &ses, &tcon);
		}
		if (rc == -EACCES || rc == -EOPNOTSUPP || !server || !ses)
			break;
		if (!tcon)
			continue;
		/* Make sure that requests go through new root servers */
		if (is_tcon_dfs(tcon)) {
			put_root_ses(root_ses);
			set_root_ses(cifs_sb, ses, &root_ses);
		}
		/* Check for remaining path components and then continue chasing them (-EREMOTE) */
		rc = check_dfs_prepath(cifs_sb, ctx, xid, server, tcon, &ref_path);
		/* Prevent recursion on broken link referrals */
		if (rc == -EREMOTE && ++count > MAX_NESTED_LINKS)
			rc = -ELOOP;
	} while (rc == -EREMOTE);

	if (rc)
		goto error;
	put_root_ses(root_ses);
	root_ses = NULL;
	kfree(ref_path);
	ref_path = NULL;
	/*
	 * Store DFS full path in both superblock and tree connect structures.
	 *
	 * For DFS root mounts, the prefix path (cifs_sb->prepath) is preserved during reconnect so
	 * only the root path is set in cifs_sb->origin_fullpath and tcon->dfs_path. And for DFS
	 * links, the prefix path is included in both and may be changed during reconnect.  See
	 * cifs_tree_connect().
	 */
	cifs_sb->origin_fullpath = kstrndup(full_path, strlen(full_path), GFP_KERNEL);
	if (!cifs_sb->origin_fullpath) {
		rc = -ENOMEM;
		goto error;
	}
	spin_lock(&cifs_tcp_ses_lock);
	tcon->dfs_path = full_path;
	full_path = NULL;
	tcon->remap = cifs_remap(cifs_sb);
	spin_unlock(&cifs_tcp_ses_lock);

	/* Add original context for DFS cache to be used when refreshing referrals */
	rc = dfs_cache_add_vol(mntdata, ctx, cifs_sb->origin_fullpath);
	if (rc)
		goto error;
	/*
	 * After reconnecting to a different server, unique ids won't
	 * match anymore, so we disable serverino. This prevents
	 * dentry revalidation to think the dentry are stale (ESTALE).
	 */
	cifs_autodisable_serverino(cifs_sb);
	/*
	 * Force the use of prefix path to support failover on DFS paths that
	 * resolve to targets that have different prefix paths.
	 */
	cifs_sb->mnt_cifs_flags |= CIFS_MOUNT_USE_PREFIX_PATH;
	kfree(cifs_sb->prepath);
	cifs_sb->prepath = ctx->prepath;
	ctx->prepath = NULL;

out:
	free_xid(xid);
	cifs_try_adding_channels(cifs_sb, ses);
	return mount_setup_tlink(cifs_sb, ses, tcon);

error:
	kfree(ref_path);
	kfree(full_path);
	kfree(mntdata);
	kfree(cifs_sb->origin_fullpath);
	put_root_ses(root_ses);
	mount_put_conns(cifs_sb, xid, server, ses, tcon);
	return rc;
}
#else
int cifs_mount(struct cifs_sb_info *cifs_sb, struct smb3_fs_context *ctx)
{
	int rc = 0;
	unsigned int xid;
	struct cifs_ses *ses;
	struct cifs_tcon *tcon;
	struct TCP_Server_Info *server;

	rc = mount_get_conns(ctx, cifs_sb, &xid, &server, &ses, &tcon);
	if (rc)
		goto error;

	if (tcon) {
		rc = is_path_remote(cifs_sb, ctx, xid, server, tcon);
		if (rc == -EREMOTE)
			rc = -EOPNOTSUPP;
		if (rc)
			goto error;
	}

	free_xid(xid);

	return mount_setup_tlink(cifs_sb, ses, tcon);

error:
	mount_put_conns(cifs_sb, xid, server, ses, tcon);
	return rc;
}
#endif

/*
 * Issue a TREE_CONNECT request.
 */
int
CIFSTCon(const unsigned int xid, struct cifs_ses *ses,
	 const char *tree, struct cifs_tcon *tcon,
	 const struct nls_table *nls_codepage)
{
	struct smb_hdr *smb_buffer;
	struct smb_hdr *smb_buffer_response;
	TCONX_REQ *pSMB;
	TCONX_RSP *pSMBr;
	unsigned char *bcc_ptr;
	int rc = 0;
	int length;
	__u16 bytes_left, count;

	if (ses == NULL)
		return -EIO;

	smb_buffer = cifs_buf_get();
	if (smb_buffer == NULL)
		return -ENOMEM;

	smb_buffer_response = smb_buffer;

	header_assemble(smb_buffer, SMB_COM_TREE_CONNECT_ANDX,
			NULL /*no tid */ , 4 /*wct */ );

	smb_buffer->Mid = get_next_mid(ses->server);
	smb_buffer->Uid = ses->Suid;
	pSMB = (TCONX_REQ *) smb_buffer;
	pSMBr = (TCONX_RSP *) smb_buffer_response;

	pSMB->AndXCommand = 0xFF;
	pSMB->Flags = cpu_to_le16(TCON_EXTENDED_SECINFO);
	bcc_ptr = &pSMB->Password[0];
	if (tcon->pipe || (ses->server->sec_mode & SECMODE_USER)) {
		pSMB->PasswordLength = cpu_to_le16(1);	/* minimum */
		*bcc_ptr = 0; /* password is null byte */
		bcc_ptr++;              /* skip password */
		/* already aligned so no need to do it below */
	} else {
		pSMB->PasswordLength = cpu_to_le16(CIFS_AUTH_RESP_SIZE);
		/* BB FIXME add code to fail this if NTLMv2 or Kerberos
		   specified as required (when that support is added to
		   the vfs in the future) as only NTLM or the much
		   weaker LANMAN (which we do not send by default) is accepted
		   by Samba (not sure whether other servers allow
		   NTLMv2 password here) */
#ifdef CONFIG_CIFS_WEAK_PW_HASH
		if ((global_secflags & CIFSSEC_MAY_LANMAN) &&
		    (ses->sectype == LANMAN))
			calc_lanman_hash(tcon->password, ses->server->cryptkey,
					 ses->server->sec_mode &
					    SECMODE_PW_ENCRYPT ? true : false,
					 bcc_ptr);
		else
#endif /* CIFS_WEAK_PW_HASH */
		rc = SMBNTencrypt(tcon->password, ses->server->cryptkey,
					bcc_ptr, nls_codepage);
		if (rc) {
			cifs_dbg(FYI, "%s Can't generate NTLM rsp. Error: %d\n",
				 __func__, rc);
			cifs_buf_release(smb_buffer);
			return rc;
		}

		bcc_ptr += CIFS_AUTH_RESP_SIZE;
		if (ses->capabilities & CAP_UNICODE) {
			/* must align unicode strings */
			*bcc_ptr = 0; /* null byte password */
			bcc_ptr++;
		}
	}

	if (ses->server->sign)
		smb_buffer->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;

	if (ses->capabilities & CAP_STATUS32) {
		smb_buffer->Flags2 |= SMBFLG2_ERR_STATUS;
	}
	if (ses->capabilities & CAP_DFS) {
		smb_buffer->Flags2 |= SMBFLG2_DFS;
	}
	if (ses->capabilities & CAP_UNICODE) {
		smb_buffer->Flags2 |= SMBFLG2_UNICODE;
		length =
		    cifs_strtoUTF16((__le16 *) bcc_ptr, tree,
			6 /* max utf8 char length in bytes */ *
			(/* server len*/ + 256 /* share len */), nls_codepage);
		bcc_ptr += 2 * length;	/* convert num 16 bit words to bytes */
		bcc_ptr += 2;	/* skip trailing null */
	} else {		/* ASCII */
		strcpy(bcc_ptr, tree);
		bcc_ptr += strlen(tree) + 1;
	}
	strcpy(bcc_ptr, "?????");
	bcc_ptr += strlen("?????");
	bcc_ptr += 1;
	count = bcc_ptr - &pSMB->Password[0];
	be32_add_cpu(&pSMB->hdr.smb_buf_length, count);
	pSMB->ByteCount = cpu_to_le16(count);

	rc = SendReceive(xid, ses, smb_buffer, smb_buffer_response, &length,
			 0);

	/* above now done in SendReceive */
	if (rc == 0) {
		bool is_unicode;

		tcon->tidStatus = CifsGood;
		tcon->need_reconnect = false;
		tcon->tid = smb_buffer_response->Tid;
		bcc_ptr = pByteArea(smb_buffer_response);
		bytes_left = get_bcc(smb_buffer_response);
		length = strnlen(bcc_ptr, bytes_left - 2);
		if (smb_buffer->Flags2 & SMBFLG2_UNICODE)
			is_unicode = true;
		else
			is_unicode = false;


		/* skip service field (NB: this field is always ASCII) */
		if (length == 3) {
			if ((bcc_ptr[0] == 'I') && (bcc_ptr[1] == 'P') &&
			    (bcc_ptr[2] == 'C')) {
				cifs_dbg(FYI, "IPC connection\n");
				tcon->ipc = true;
				tcon->pipe = true;
			}
		} else if (length == 2) {
			if ((bcc_ptr[0] == 'A') && (bcc_ptr[1] == ':')) {
				/* the most common case */
				cifs_dbg(FYI, "disk share connection\n");
			}
		}
		bcc_ptr += length + 1;
		bytes_left -= (length + 1);
		strlcpy(tcon->treeName, tree, sizeof(tcon->treeName));

		/* mostly informational -- no need to fail on error here */
		kfree(tcon->nativeFileSystem);
		tcon->nativeFileSystem = cifs_strndup_from_utf16(bcc_ptr,
						      bytes_left, is_unicode,
						      nls_codepage);

		cifs_dbg(FYI, "nativeFileSystem=%s\n", tcon->nativeFileSystem);

		if ((smb_buffer_response->WordCount == 3) ||
			 (smb_buffer_response->WordCount == 7))
			/* field is in same location */
			tcon->Flags = le16_to_cpu(pSMBr->OptionalSupport);
		else
			tcon->Flags = 0;
		cifs_dbg(FYI, "Tcon flags: 0x%x\n", tcon->Flags);
	}

	cifs_buf_release(smb_buffer);
	return rc;
}

static void delayed_free(struct rcu_head *p)
{
	struct cifs_sb_info *cifs_sb = container_of(p, struct cifs_sb_info, rcu);

	unload_nls(cifs_sb->local_nls);
	smb3_cleanup_fs_context(cifs_sb->ctx);
	kfree(cifs_sb);
}

void
cifs_umount(struct cifs_sb_info *cifs_sb)
{
	struct rb_root *root = &cifs_sb->tlink_tree;
	struct rb_node *node;
	struct tcon_link *tlink;

	cancel_delayed_work_sync(&cifs_sb->prune_tlinks);

	spin_lock(&cifs_sb->tlink_tree_lock);
	while ((node = rb_first(root))) {
		tlink = rb_entry(node, struct tcon_link, tl_rbnode);
		cifs_get_tlink(tlink);
		clear_bit(TCON_LINK_IN_TREE, &tlink->tl_flags);
		rb_erase(node, root);

		spin_unlock(&cifs_sb->tlink_tree_lock);
		cifs_put_tlink(tlink);
		spin_lock(&cifs_sb->tlink_tree_lock);
	}
	spin_unlock(&cifs_sb->tlink_tree_lock);

	kfree(cifs_sb->prepath);
#ifdef CONFIG_CIFS_DFS_UPCALL
	dfs_cache_del_vol(cifs_sb->origin_fullpath);
	kfree(cifs_sb->origin_fullpath);
#endif
	call_rcu(&cifs_sb->rcu, delayed_free);
}

int
cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses)
{
	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))
		return 0;

	rc = server->ops->negotiate(xid, ses);
	if (rc == 0) {
		spin_lock(&GlobalMid_Lock);
		if (server->tcpStatus == CifsNeedNegotiate)
			server->tcpStatus = CifsGood;
		else
			rc = -EHOSTDOWN;
		spin_unlock(&GlobalMid_Lock);
	}

	return rc;
}

int
cifs_setup_session(const unsigned int xid, struct cifs_ses *ses,
		   struct nls_table *nls_info)
{
	int rc = -ENOSYS;
	struct TCP_Server_Info *server = cifs_ses_server(ses);

	if (!ses->binding) {
		ses->capabilities = server->capabilities;
		if (!linuxExtEnabled)
			ses->capabilities &= (~server->vals->cap_unix);

		if (ses->auth_key.response) {
			cifs_dbg(FYI, "Free previous auth_key.response = %p\n",
				 ses->auth_key.response);
			kfree(ses->auth_key.response);
			ses->auth_key.response = NULL;
			ses->auth_key.len = 0;
		}
	}

	cifs_dbg(FYI, "Security Mode: 0x%x Capabilities: 0x%x TimeAdjust: %d\n",
		 server->sec_mode, server->capabilities, server->timeAdj);

	if (server->ops->sess_setup)
		rc = server->ops->sess_setup(xid, ses, nls_info);

	if (rc)
		cifs_server_dbg(VFS, "Send error in SessSetup = %d\n", rc);

	return rc;
}

static int
cifs_set_vol_auth(struct smb3_fs_context *ctx, struct cifs_ses *ses)
{
	ctx->sectype = ses->sectype;

	/* krb5 is special, since we don't need username or pw */
	if (ctx->sectype == Kerberos)
		return 0;

	return cifs_set_cifscreds(ctx, ses);
}

static struct cifs_tcon *
cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
{
	int rc;
	struct cifs_tcon *master_tcon = cifs_sb_master_tcon(cifs_sb);
	struct cifs_ses *ses;
	struct cifs_tcon *tcon = NULL;
	struct smb3_fs_context *ctx;

	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
	if (ctx == NULL)
		return ERR_PTR(-ENOMEM);

	ctx->local_nls = cifs_sb->local_nls;
	ctx->linux_uid = fsuid;
	ctx->cred_uid = fsuid;
	ctx->UNC = master_tcon->treeName;
	ctx->retry = master_tcon->retry;
	ctx->nocase = master_tcon->nocase;
	ctx->nohandlecache = master_tcon->nohandlecache;
	ctx->local_lease = master_tcon->local_lease;
	ctx->no_lease = master_tcon->no_lease;
	ctx->resilient = master_tcon->use_resilient;
	ctx->persistent = master_tcon->use_persistent;
	ctx->handle_timeout = master_tcon->handle_timeout;
	ctx->no_linux_ext = !master_tcon->unix_ext;
	ctx->linux_ext = master_tcon->posix_extensions;
	ctx->sectype = master_tcon->ses->sectype;
	ctx->sign = master_tcon->ses->sign;
	ctx->seal = master_tcon->seal;
#ifdef CONFIG_CIFS_SWN_UPCALL
	ctx->witness = master_tcon->use_witness;
#endif

	rc = cifs_set_vol_auth(ctx, master_tcon->ses);
	if (rc) {
		tcon = ERR_PTR(rc);
		goto out;
	}

	/* get a reference for the same TCP session */
	spin_lock(&cifs_tcp_ses_lock);
	++master_tcon->ses->server->srv_count;
	spin_unlock(&cifs_tcp_ses_lock);

	ses = cifs_get_smb_ses(master_tcon->ses->server, ctx);
	if (IS_ERR(ses)) {
		tcon = (struct cifs_tcon *)ses;
		cifs_put_tcp_session(master_tcon->ses->server, 0);
		goto out;
	}

	tcon = cifs_get_tcon(ses, ctx);
	if (IS_ERR(tcon)) {
		cifs_put_smb_ses(ses);
		goto out;
	}

	if (cap_unix(ses))
		reset_cifs_unix_caps(0, tcon, NULL, ctx);

out:
	kfree(ctx->username);
	kfree_sensitive(ctx->password);
	kfree(ctx);

	return tcon;
}

struct cifs_tcon *
cifs_sb_master_tcon(struct cifs_sb_info *cifs_sb)
{
	return tlink_tcon(cifs_sb_master_tlink(cifs_sb));
}

/* find and return a tlink with given uid */
static struct tcon_link *
tlink_rb_search(struct rb_root *root, kuid_t uid)
{
	struct rb_node *node = root->rb_node;
	struct tcon_link *tlink;

	while (node) {
		tlink = rb_entry(node, struct tcon_link, tl_rbnode);

		if (uid_gt(tlink->tl_uid, uid))
			node = node->rb_left;
		else if (uid_lt(tlink->tl_uid, uid))
			node = node->rb_right;
		else
			return tlink;
	}
	return NULL;
}

/* insert a tcon_link into the tree */
static void
tlink_rb_insert(struct rb_root *root, struct tcon_link *new_tlink)
{
	struct rb_node **new = &(root->rb_node), *parent = NULL;
	struct tcon_link *tlink;

	while (*new) {
		tlink = rb_entry(*new, struct tcon_link, tl_rbnode);
		parent = *new;

		if (uid_gt(tlink->tl_uid, new_tlink->tl_uid))
			new = &((*new)->rb_left);
		else
			new = &((*new)->rb_right);
	}

	rb_link_node(&new_tlink->tl_rbnode, parent, new);
	rb_insert_color(&new_tlink->tl_rbnode, root);
}

/*
 * Find or construct an appropriate tcon given a cifs_sb and the fsuid of the
 * current task.
 *
 * If the superblock doesn't refer to a multiuser mount, then just return
 * the master tcon for the mount.
 *
 * First, search the rbtree for an existing tcon for this fsuid. If one
 * exists, then check to see if it's pending construction. If it is then wait
 * for construction to complete. Once it's no longer pending, check to see if
 * it failed and either return an error or retry construction, depending on
 * the timeout.
 *
 * If one doesn't exist then insert a new tcon_link struct into the tree and
 * try to construct a new one.
 */
struct tcon_link *
cifs_sb_tlink(struct cifs_sb_info *cifs_sb)
{
	int ret;
	kuid_t fsuid = current_fsuid();
	struct tcon_link *tlink, *newtlink;

	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
		return cifs_get_tlink(cifs_sb_master_tlink(cifs_sb));

	spin_lock(&cifs_sb->tlink_tree_lock);
	tlink = tlink_rb_search(&cifs_sb->tlink_tree, fsuid);
	if (tlink)
		cifs_get_tlink(tlink);
	spin_unlock(&cifs_sb->tlink_tree_lock);

	if (tlink == NULL) {
		newtlink = kzalloc(sizeof(*tlink), GFP_KERNEL);
		if (newtlink == NULL)
			return ERR_PTR(-ENOMEM);
		newtlink->tl_uid = fsuid;
		newtlink->tl_tcon = ERR_PTR(-EACCES);
		set_bit(TCON_LINK_PENDING, &newtlink->tl_flags);
		set_bit(TCON_LINK_IN_TREE, &newtlink->tl_flags);
		cifs_get_tlink(newtlink);

		spin_lock(&cifs_sb->tlink_tree_lock);
		/* was one inserted after previous search? */
		tlink = tlink_rb_search(&cifs_sb->tlink_tree, fsuid);
		if (tlink) {
			cifs_get_tlink(tlink);
			spin_unlock(&cifs_sb->tlink_tree_lock);
			kfree(newtlink);
			goto wait_for_construction;
		}
		tlink = newtlink;
		tlink_rb_insert(&cifs_sb->tlink_tree, tlink);
		spin_unlock(&cifs_sb->tlink_tree_lock);
	} else {
wait_for_construction:
		ret = wait_on_bit(&tlink->tl_flags, TCON_LINK_PENDING,
				  TASK_INTERRUPTIBLE);
		if (ret) {
			cifs_put_tlink(tlink);
			return ERR_PTR(-ERESTARTSYS);
		}

		/* if it's good, return it */
		if (!IS_ERR(tlink->tl_tcon))
			return tlink;

		/* return error if we tried this already recently */
		if (time_before(jiffies, tlink->tl_time + TLINK_ERROR_EXPIRE)) {
			cifs_put_tlink(tlink);
			return ERR_PTR(-EACCES);
		}

		if (test_and_set_bit(TCON_LINK_PENDING, &tlink->tl_flags))
			goto wait_for_construction;
	}

	tlink->tl_tcon = cifs_construct_tcon(cifs_sb, fsuid);
	clear_bit(TCON_LINK_PENDING, &tlink->tl_flags);
	wake_up_bit(&tlink->tl_flags, TCON_LINK_PENDING);

	if (IS_ERR(tlink->tl_tcon)) {
		cifs_put_tlink(tlink);
		return ERR_PTR(-EACCES);
	}

	return tlink;
}

/*
 * periodic workqueue job that scans tcon_tree for a superblock and closes
 * out tcons.
 */
static void
cifs_prune_tlinks(struct work_struct *work)
{
	struct cifs_sb_info *cifs_sb = container_of(work, struct cifs_sb_info,
						    prune_tlinks.work);
	struct rb_root *root = &cifs_sb->tlink_tree;
	struct rb_node *node;
	struct rb_node *tmp;
	struct tcon_link *tlink;

	/*
	 * Because we drop the spinlock in the loop in order to put the tlink
	 * it's not guarded against removal of links from the tree. The only
	 * places that remove entries from the tree are this function and
	 * umounts. Because this function is non-reentrant and is canceled
	 * before umount can proceed, this is safe.
	 */
	spin_lock(&cifs_sb->tlink_tree_lock);
	node = rb_first(root);
	while (node != NULL) {
		tmp = node;
		node = rb_next(tmp);
		tlink = rb_entry(tmp, struct tcon_link, tl_rbnode);

		if (test_bit(TCON_LINK_MASTER, &tlink->tl_flags) ||
		    atomic_read(&tlink->tl_count) != 0 ||
		    time_after(tlink->tl_time + TLINK_IDLE_EXPIRE, jiffies))
			continue;

		cifs_get_tlink(tlink);
		clear_bit(TCON_LINK_IN_TREE, &tlink->tl_flags);
		rb_erase(tmp, root);

		spin_unlock(&cifs_sb->tlink_tree_lock);
		cifs_put_tlink(tlink);
		spin_lock(&cifs_sb->tlink_tree_lock);
	}
	spin_unlock(&cifs_sb->tlink_tree_lock);

	queue_delayed_work(cifsiod_wq, &cifs_sb->prune_tlinks,
				TLINK_IDLE_EXPIRE);
}

#ifdef CONFIG_CIFS_DFS_UPCALL
int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const struct nls_table *nlsc)
{
	int rc;
	struct TCP_Server_Info *server = tcon->ses->server;
	const struct smb_version_operations *ops = server->ops;
	struct dfs_cache_tgt_list tl;
	struct dfs_cache_tgt_iterator *it = NULL;
	char *tree;
	const char *tcp_host;
	size_t tcp_host_len;
	const char *dfs_host;
	size_t dfs_host_len;
	char *share = NULL, *prefix = NULL;
	struct dfs_info3_param ref = {0};
	bool isroot;

	tree = kzalloc(MAX_TREE_SIZE, GFP_KERNEL);
	if (!tree)
		return -ENOMEM;

	if (!tcon->dfs_path) {
		if (tcon->ipc) {
			scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", server->hostname);
			rc = ops->tree_connect(xid, tcon->ses, tree, tcon, nlsc);
		} else {
			rc = ops->tree_connect(xid, tcon->ses, tcon->treeName, tcon, nlsc);
		}
		goto out;
	}

	rc = dfs_cache_noreq_find(tcon->dfs_path + 1, &ref, &tl);
	if (rc)
		goto out;
	isroot = ref.server_type == DFS_TYPE_ROOT;
	free_dfs_info_param(&ref);

	extract_unc_hostname(server->hostname, &tcp_host, &tcp_host_len);

	for (it = dfs_cache_get_tgt_iterator(&tl); it; it = dfs_cache_get_next_tgt(&tl, it)) {
		bool target_match;

		kfree(share);
		kfree(prefix);
		share = NULL;
		prefix = NULL;

		rc = dfs_cache_get_tgt_share(tcon->dfs_path + 1, it, &share, &prefix);
		if (rc) {
			cifs_dbg(VFS, "%s: failed to parse target share %d\n",
				 __func__, rc);
			continue;
		}

		extract_unc_hostname(share, &dfs_host, &dfs_host_len);

		if (dfs_host_len != tcp_host_len
		    || strncasecmp(dfs_host, tcp_host, dfs_host_len) != 0) {
			cifs_dbg(FYI, "%s: %.*s doesn't match %.*s\n", __func__, (int)dfs_host_len,
				 dfs_host, (int)tcp_host_len, tcp_host);

			rc = match_target_ip(server, dfs_host, dfs_host_len, &target_match);
			if (rc) {
				cifs_dbg(VFS, "%s: failed to match target ip: %d\n", __func__, rc);
				break;
			}

			if (!target_match) {
				cifs_dbg(FYI, "%s: skipping target\n", __func__);
				continue;
			}
		}

		if (tcon->ipc) {
			scnprintf(tree, MAX_TREE_SIZE, "\\\\%s\\IPC$", share);
			rc = ops->tree_connect(xid, tcon->ses, tree, tcon, nlsc);
		} else {
			scnprintf(tree, MAX_TREE_SIZE, "\\%s", share);
			rc = ops->tree_connect(xid, tcon->ses, tree, tcon, nlsc);
			/* Only handle prefix paths of DFS link targets */
			if (!rc && !isroot) {
				rc = update_super_prepath(tcon, prefix);
				break;
			}
		}
		if (rc == -EREMOTE)
			break;
	}

	kfree(share);
	kfree(prefix);

	if (!rc) {
		if (it)
			rc = dfs_cache_noreq_update_tgthint(tcon->dfs_path + 1, it);
		else
			rc = -ENOENT;
	}
	dfs_cache_free_tgts(&tl);
out:
	kfree(tree);
	return rc;
}
#else
int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const struct nls_table *nlsc)
{
	const struct smb_version_operations *ops = tcon->ses->server->ops;

	return ops->tree_connect(xid, tcon->ses, tcon->treeName, tcon, nlsc);
}
#endif