/*
 *   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/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.
 */
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;
}

#ifdef CONFIG_CIFS_DFS_UPCALL
/* 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));
        }

        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
                if (cifs_sb && cifs_sb->origin_fullpath)
                        /*
                         * 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);
                else {
#endif
                        /*
                         * Resolve the hostname again to make sure that IP address is up-to-date.
                         */
                        rc = reconn_set_ipaddr_from_hostname(server);
                        if (rc) {
                                cifs_dbg(FYI, "%s: failed to resolve hostname: %d\n",
                                                __func__, rc);
                        }

#ifdef CONFIG_CIFS_DFS_UPCALL
                }
#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);
                }
                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);

        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;

        /*
         * 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);
        }
}


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 (strcasecmp(server->hostname, ctx->server_hostname))
                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;
        kfree(server->hostname);

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

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->hostname = kstrdup(ctx->server_hostname, GFP_KERNEL);
        if (!tcp_ses->hostname) {
                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->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) {
                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.
 *
 * On session close, the IPC is closed and the server must release all tcons of the session.
 * No need to send a tree disconnect here.
 *
 * Besides, it will make the server to not close durable and resilient files on session close, as
 * specified in MS-SMB2 3.3.5.6 Receiving an SMB2 LOGOFF Request.
 */
static int
cifs_free_ipc(struct cifs_ses *ses)
{
        struct cifs_tcon *tcon = ses->tcon_ipc;

        if (tcon == NULL)
                return 0;

        tconInfoFree(tcon);
        ses->tcon_ipc = NULL;
        return 0;
}

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;
        }

        cifs_dbg(FYI, "%s: ses_count=%d\n", __func__, ses->ses_count);
        cifs_dbg(FYI, "%s: ses ipc: %s\n", __func__, ses->tcon_ipc ? ses->tcon_ipc->treeName : "NONE");

        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 = kstrdup(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 = 1;
        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->acregmax != new->ctx->acregmax)
                return 0;
        if (old->ctx->acdirmax != new->ctx->acdirmax)
                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 == 0) {
                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;