/*
 *   fs/cifs/smb2pdu.c
 *
 *   Copyright (C) International Business Machines  Corp., 2009, 2013
 *                 Etersoft, 2012
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *              Pavel Shilovsky (pshilovsky@samba.org) 2012
 *
 *   Contains the routines for constructing the SMB2 PDUs themselves
 *
 *   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
 */

 /* SMB2 PDU handling routines here - except for leftovers (eg session setup) */
 /* Note that there are handle based routines which must be                   */
 /* treated slightly differently for reconnection purposes since we never     */
 /* want to reuse a stale file handle and only the caller knows the file info */

#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/vfs.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/uaccess.h>
#include <linux/pagemap.h>
#include <linux/xattr.h>
#include "smb2pdu.h"
#include "cifsglob.h"
#include "cifsacl.h"
#include "cifsproto.h"
#include "smb2proto.h"
#include "cifs_unicode.h"
#include "cifs_debug.h"
#include "ntlmssp.h"
#include "smb2status.h"
#include "smb2glob.h"
#include "cifspdu.h"
#include "cifs_spnego.h"

/*
 *  The following table defines the expected "StructureSize" of SMB2 requests
 *  in order by SMB2 command.  This is similar to "wct" in SMB/CIFS requests.
 *
 *  Note that commands are defined in smb2pdu.h in le16 but the array below is
 *  indexed by command in host byte order.
 */
static const int smb2_req_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
        /* SMB2_NEGOTIATE */ 36,
        /* SMB2_SESSION_SETUP */ 25,
        /* SMB2_LOGOFF */ 4,
        /* SMB2_TREE_CONNECT */ 9,
        /* SMB2_TREE_DISCONNECT */ 4,
        /* SMB2_CREATE */ 57,
        /* SMB2_CLOSE */ 24,
        /* SMB2_FLUSH */ 24,
        /* SMB2_READ */ 49,
        /* SMB2_WRITE */ 49,
        /* SMB2_LOCK */ 48,
        /* SMB2_IOCTL */ 57,
        /* SMB2_CANCEL */ 4,
        /* SMB2_ECHO */ 4,
        /* SMB2_QUERY_DIRECTORY */ 33,
        /* SMB2_CHANGE_NOTIFY */ 32,
        /* SMB2_QUERY_INFO */ 41,
        /* SMB2_SET_INFO */ 33,
        /* SMB2_OPLOCK_BREAK */ 24 /* BB this is 36 for LEASE_BREAK variant */
};


static void
smb2_hdr_assemble(struct smb2_hdr *hdr, __le16 smb2_cmd /* command */ ,
                  const struct cifs_tcon *tcon)
{
        struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
        char *temp = (char *)hdr;
        /* lookup word count ie StructureSize from table */
        __u16 parmsize = smb2_req_struct_sizes[le16_to_cpu(smb2_cmd)];

        /*
         * smaller than SMALL_BUFFER_SIZE but bigger than fixed area of
         * largest operations (Create)
         */
        memset(temp, 0, 256);

        /* Note this is only network field converted to big endian */
        hdr->smb2_buf_length = cpu_to_be32(parmsize + sizeof(struct smb2_hdr)
                        - 4 /*  RFC 1001 length field itself not counted */);

        hdr->ProtocolId = SMB2_PROTO_NUMBER;
        hdr->StructureSize = cpu_to_le16(64);
        hdr->Command = smb2_cmd;
        if (tcon && tcon->ses && tcon->ses->server) {
                struct TCP_Server_Info *server = tcon->ses->server;

                spin_lock(&server->req_lock);
                /* Request up to 2 credits but don't go over the limit. */
                if (server->credits >= server->max_credits)
                        hdr->CreditRequest = cpu_to_le16(0);
                else
                        hdr->CreditRequest = cpu_to_le16(
                                min_t(int, server->max_credits -
                                                server->credits, 2));
                spin_unlock(&server->req_lock);
        } else {
                hdr->CreditRequest = cpu_to_le16(2);
        }
        hdr->ProcessId = cpu_to_le32((__u16)current->tgid);

        if (!tcon)
                goto out;

        /* GLOBAL_CAP_LARGE_MTU will only be set if dialect > SMB2.02 */
        /* See sections 2.2.4 and 3.2.4.1.5 of MS-SMB2 */
        if ((tcon->ses) && (tcon->ses->server) &&
            (tcon->ses->server->capabilities & SMB2_GLOBAL_CAP_LARGE_MTU))
                hdr->CreditCharge = cpu_to_le16(1);
        /* else CreditCharge MBZ */

        hdr->TreeId = tcon->tid;
        /* Uid is not converted */
        if (tcon->ses)
                hdr->SessionId = tcon->ses->Suid;

        /*
         * If we would set SMB2_FLAGS_DFS_OPERATIONS on open we also would have
         * to pass the path on the Open SMB prefixed by \\server\share.
         * Not sure when we would need to do the augmented path (if ever) and
         * setting this flag breaks the SMB2 open operation since it is
         * illegal to send an empty path name (without \\server\share prefix)
         * when the DFS flag is set in the SMB open header. We could
         * consider setting the flag on all operations other than open
         * but it is safer to net set it for now.
         */
/*      if (tcon->share_flags & SHI1005_FLAGS_DFS)
                hdr->Flags |= SMB2_FLAGS_DFS_OPERATIONS; */

        if (tcon->ses && tcon->ses->server && tcon->ses->server->sign)
                hdr->Flags |= SMB2_FLAGS_SIGNED;
out:
        pdu->StructureSize2 = cpu_to_le16(parmsize);
        return;
}

static int
smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon)
{
        int rc = 0;
        struct nls_table *nls_codepage;
        struct cifs_ses *ses;
        struct TCP_Server_Info *server;

        /*
         * SMB2s NegProt, SessSetup, Logoff do not have tcon yet so
         * check for tcp and smb session status done differently
         * for those three - in the calling routine.
         */
        if (tcon == NULL)
                return rc;

        if (smb2_command == SMB2_TREE_CONNECT)
                return rc;

        if (tcon->tidStatus == CifsExiting) {
                /*
                 * only tree disconnect, open, and write,
                 * (and ulogoff which does not have tcon)
                 * are allowed as we start force umount.
                 */
                if ((smb2_command != SMB2_WRITE) &&
                   (smb2_command != SMB2_CREATE) &&
                   (smb2_command != SMB2_TREE_DISCONNECT)) {
                        cifs_dbg(FYI, "can not send cmd %d while umounting\n",
                                 smb2_command);
                        return -ENODEV;
                }
        }
        if ((!tcon->ses) || (tcon->ses->status == CifsExiting) ||
            (!tcon->ses->server))
                return -EIO;

        ses = tcon->ses;
        server = ses->server;

        /*
         * Give demultiplex thread up to 10 seconds to reconnect, should be
         * greater than cifs socket timeout which is 7 seconds
         */
        while (server->tcpStatus == CifsNeedReconnect) {
                /*
                 * Return to caller for TREE_DISCONNECT and LOGOFF and CLOSE
                 * here since they are implicitly done when session drops.
                 */
                switch (smb2_command) {
                /*
                 * BB Should we keep oplock break and add flush to exceptions?
                 */
                case SMB2_TREE_DISCONNECT:
                case SMB2_CANCEL:
                case SMB2_CLOSE:
                case SMB2_OPLOCK_BREAK:
                        return -EAGAIN;
                }

                wait_event_interruptible_timeout(server->response_q,
                        (server->tcpStatus != CifsNeedReconnect), 10 * HZ);

                /* are we still trying to reconnect? */
                if (server->tcpStatus != CifsNeedReconnect)
                        break;

                /*
                 * on "soft" mounts we wait once. Hard mounts keep
                 * retrying until process is killed or server comes
                 * back on-line
                 */
                if (!tcon->retry) {
                        cifs_dbg(FYI, "gave up waiting on reconnect in smb_init\n");
                        return -EHOSTDOWN;
                }
        }

        if (!tcon->ses->need_reconnect && !tcon->need_reconnect)
                return rc;

        nls_codepage = load_nls_default();

        /*
         * need to prevent multiple threads trying to simultaneously reconnect
         * the same SMB session
         */
        mutex_lock(&tcon->ses->session_mutex);
        rc = cifs_negotiate_protocol(0, tcon->ses);
        if (!rc && tcon->ses->need_reconnect)
                rc = cifs_setup_session(0, tcon->ses, nls_codepage);

        if (rc || !tcon->need_reconnect) {
                mutex_unlock(&tcon->ses->session_mutex);
                goto out;
        }

        cifs_mark_open_files_invalid(tcon);
        if (tcon->use_persistent)
                tcon->need_reopen_files = true;

        rc = SMB2_tcon(0, tcon->ses, tcon->treeName, tcon, nls_codepage);
        mutex_unlock(&tcon->ses->session_mutex);

        cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc);
        if (rc)
                goto out;

        if (smb2_command != SMB2_INTERNAL_CMD)
                queue_delayed_work(cifsiod_wq, &server->reconnect, 0);

        atomic_inc(&tconInfoReconnectCount);
out:
        /*
         * Check if handle based operation so we know whether we can continue
         * or not without returning to caller to reset file handle.
         */
        /*
         * BB Is flush done by server on drop of tcp session? Should we special
         * case it and skip above?
         */
        switch (smb2_command) {
        case SMB2_FLUSH:
        case SMB2_READ:
        case SMB2_WRITE:
        case SMB2_LOCK:
        case SMB2_IOCTL:
        case SMB2_QUERY_DIRECTORY:
        case SMB2_CHANGE_NOTIFY:
        case SMB2_QUERY_INFO:
        case SMB2_SET_INFO:
                rc = -EAGAIN;
        }
        unload_nls(nls_codepage);
        return rc;
}

/*
 * Allocate and return pointer to an SMB request hdr, and set basic
 * SMB information in the SMB header. If the return code is zero, this
 * function must have filled in request_buf pointer.
 */
static int
small_smb2_init(__le16 smb2_command, struct cifs_tcon *tcon,
                void **request_buf)
{
        int rc = 0;

        rc = smb2_reconnect(smb2_command, tcon);
        if (rc)
                return rc;

        /* BB eventually switch this to SMB2 specific small buf size */
        *request_buf = cifs_small_buf_get();
        if (*request_buf == NULL) {
                /* BB should we add a retry in here if not a writepage? */
                return -ENOMEM;
        }

        smb2_hdr_assemble((struct smb2_hdr *) *request_buf, smb2_command, tcon);

        if (tcon != NULL) {
#ifdef CONFIG_CIFS_STATS2
                uint16_t com_code = le16_to_cpu(smb2_command);
                cifs_stats_inc(&tcon->stats.smb2_stats.smb2_com_sent[com_code]);
#endif
                cifs_stats_inc(&tcon->num_smbs_sent);
        }

        return rc;
}

#ifdef CONFIG_CIFS_SMB311
/* offset is sizeof smb2_negotiate_req - 4 but rounded up to 8 bytes */
#define OFFSET_OF_NEG_CONTEXT 0x68  /* sizeof(struct smb2_negotiate_req) - 4 */


#define SMB2_PREAUTH_INTEGRITY_CAPABILITIES     cpu_to_le16(1)
#define SMB2_ENCRYPTION_CAPABILITIES            cpu_to_le16(2)

static void
build_preauth_ctxt(struct smb2_preauth_neg_context *pneg_ctxt)
{
        pneg_ctxt->ContextType = SMB2_PREAUTH_INTEGRITY_CAPABILITIES;
        pneg_ctxt->DataLength = cpu_to_le16(38);
        pneg_ctxt->HashAlgorithmCount = cpu_to_le16(1);
        pneg_ctxt->SaltLength = cpu_to_le16(SMB311_SALT_SIZE);
        get_random_bytes(pneg_ctxt->Salt, SMB311_SALT_SIZE);
        pneg_ctxt->HashAlgorithms = SMB2_PREAUTH_INTEGRITY_SHA512;
}

static void
build_encrypt_ctxt(struct smb2_encryption_neg_context *pneg_ctxt)
{
        pneg_ctxt->ContextType = SMB2_ENCRYPTION_CAPABILITIES;
        pneg_ctxt->DataLength = cpu_to_le16(6);
        pneg_ctxt->CipherCount = cpu_to_le16(2);
        pneg_ctxt->Ciphers[0] = SMB2_ENCRYPTION_AES128_GCM;
        pneg_ctxt->Ciphers[1] = SMB2_ENCRYPTION_AES128_CCM;
}

static void
assemble_neg_contexts(struct smb2_negotiate_req *req)
{

        /* +4 is to account for the RFC1001 len field */
        char *pneg_ctxt = (char *)req + OFFSET_OF_NEG_CONTEXT + 4;

        build_preauth_ctxt((struct smb2_preauth_neg_context *)pneg_ctxt);
        /* Add 2 to size to round to 8 byte boundary */
        pneg_ctxt += 2 + sizeof(struct smb2_preauth_neg_context);
        build_encrypt_ctxt((struct smb2_encryption_neg_context *)pneg_ctxt);
        req->NegotiateContextOffset = cpu_to_le32(OFFSET_OF_NEG_CONTEXT);
        req->NegotiateContextCount = cpu_to_le16(2);
        inc_rfc1001_len(req, 4 + sizeof(struct smb2_preauth_neg_context) + 2
                        + sizeof(struct smb2_encryption_neg_context)); /* calculate hash */
}
#else
static void assemble_neg_contexts(struct smb2_negotiate_req *req)
{
        return;
}
#endif /* SMB311 */


/*
 *
 *      SMB2 Worker functions follow:
 *
 *      The general structure of the worker functions is:
 *      1) Call smb2_init (assembles SMB2 header)
 *      2) Initialize SMB2 command specific fields in fixed length area of SMB
 *      3) Call smb_sendrcv2 (sends request on socket and waits for response)
 *      4) Decode SMB2 command specific fields in the fixed length area
 *      5) Decode variable length data area (if any for this SMB2 command type)
 *      6) Call free smb buffer
 *      7) return
 *
 */

int
SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
{
        struct smb2_negotiate_req *req;
        struct smb2_negotiate_rsp *rsp;
        struct kvec iov[1];
        int rc = 0;
        int resp_buftype;
        struct TCP_Server_Info *server = ses->server;
        int blob_offset, blob_length;
        char *security_blob;
        int flags = CIFS_NEG_OP;

        cifs_dbg(FYI, "Negotiate protocol\n");

        if (!server) {
                WARN(1, "%s: server is NULL!\n", __func__);
                return -EIO;
        }

        rc = small_smb2_init(SMB2_NEGOTIATE, NULL, (void **) &req);
        if (rc)
                return rc;

        req->hdr.SessionId = 0;

        req->Dialects[0] = cpu_to_le16(ses->server->vals->protocol_id);

        req->DialectCount = cpu_to_le16(1); /* One vers= at a time for now */
        inc_rfc1001_len(req, 2);

        /* only one of SMB2 signing flags may be set in SMB2 request */
        if (ses->sign)
                req->SecurityMode = cpu_to_le16(SMB2_NEGOTIATE_SIGNING_REQUIRED);
        else if (global_secflags & CIFSSEC_MAY_SIGN)
                req->SecurityMode = cpu_to_le16(SMB2_NEGOTIATE_SIGNING_ENABLED);
        else
                req->SecurityMode = 0;

        req->Capabilities = cpu_to_le32(ses->server->vals->req_capabilities);

        /* ClientGUID must be zero for SMB2.02 dialect */
        if (ses->server->vals->protocol_id == SMB20_PROT_ID)
                memset(req->ClientGUID, 0, SMB2_CLIENT_GUID_SIZE);
        else {
                memcpy(req->ClientGUID, server->client_guid,
                        SMB2_CLIENT_GUID_SIZE);
                if (ses->server->vals->protocol_id == SMB311_PROT_ID)
                        assemble_neg_contexts(req);
        }
        iov[0].iov_base = (char *)req;
        /* 4 for rfc1002 length field */
        iov[0].iov_len = get_rfc1002_length(req) + 4;

        rc = SendReceive2(xid, ses, iov, 1, &resp_buftype, flags);

        rsp = (struct smb2_negotiate_rsp *)iov[0].iov_base;
        /*
         * No tcon so can't do
         * cifs_stats_inc(&tcon->stats.smb2_stats.smb2_com_fail[SMB2...]);
         */
        if (rc != 0)
                goto neg_exit;

        cifs_dbg(FYI, "mode 0x%x\n", rsp->SecurityMode);

        /* BB we may eventually want to match the negotiated vs. requested
           dialect, even though we are only requesting one at a time */
        if (rsp->DialectRevision == cpu_to_le16(SMB20_PROT_ID))
                cifs_dbg(FYI, "negotiated smb2.0 dialect\n");
        else if (rsp->DialectRevision == cpu_to_le16(SMB21_PROT_ID))
                cifs_dbg(FYI, "negotiated smb2.1 dialect\n");
        else if (rsp->DialectRevision == cpu_to_le16(SMB30_PROT_ID))
                cifs_dbg(FYI, "negotiated smb3.0 dialect\n");
        else if (rsp->DialectRevision == cpu_to_le16(SMB302_PROT_ID))
                cifs_dbg(FYI, "negotiated smb3.02 dialect\n");
#ifdef CONFIG_CIFS_SMB311
        else if (rsp->DialectRevision == cpu_to_le16(SMB311_PROT_ID))
                cifs_dbg(FYI, "negotiated smb3.1.1 dialect\n");
#endif /* SMB311 */
        else {
                cifs_dbg(VFS, "Illegal dialect returned by server 0x%x\n",
                         le16_to_cpu(rsp->DialectRevision));
                rc = -EIO;
                goto neg_exit;
        }
        server->dialect = le16_to_cpu(rsp->DialectRevision);

        /* SMB2 only has an extended negflavor */
        server->negflavor = CIFS_NEGFLAVOR_EXTENDED;
        /* set it to the maximum buffer size value we can send with 1 credit */
        server->maxBuf = min_t(unsigned int, le32_to_cpu(rsp->MaxTransactSize),
                               SMB2_MAX_BUFFER_SIZE);
        server->max_read = le32_to_cpu(rsp->MaxReadSize);
        server->max_write = le32_to_cpu(rsp->MaxWriteSize);
        /* BB Do we need to validate the SecurityMode? */
        server->sec_mode = le16_to_cpu(rsp->SecurityMode);
        server->capabilities = le32_to_cpu(rsp->Capabilities);
        /* Internal types */
        server->capabilities |= SMB2_NT_FIND | SMB2_LARGE_FILES;

        security_blob = smb2_get_data_area_len(&blob_offset, &blob_length,
                                               &rsp->hdr);
        /*
         * See MS-SMB2 section 2.2.4: if no blob, client picks default which
         * for us will be
         *      ses->sectype = RawNTLMSSP;
         * but for time being this is our only auth choice so doesn't matter.
         * We just found a server which sets blob length to zero expecting raw.
         */
        if (blob_length == 0)
                cifs_dbg(FYI, "missing security blob on negprot\n");

        rc = cifs_enable_signing(server, ses->sign);
        if (rc)
                goto neg_exit;
        if (blob_length) {
                rc = decode_negTokenInit(security_blob, blob_length, server);
                if (rc == 1)
                        rc = 0;
                else if (rc == 0)
                        rc = -EIO;
        }
neg_exit:
        free_rsp_buf(resp_buftype, rsp);
        return rc;
}

int smb3_validate_negotiate(const unsigned int xid, struct cifs_tcon *tcon)
{
        int rc = 0;
        struct validate_negotiate_info_req vneg_inbuf;
        struct validate_negotiate_info_rsp *pneg_rsp;
        u32 rsplen;

        cifs_dbg(FYI, "validate negotiate\n");

        /*
         * validation ioctl must be signed, so no point sending this if we
         * can not sign it.  We could eventually change this to selectively
         * sign just this, the first and only signed request on a connection.
         * This is good enough for now since a user who wants better security
         * would also enable signing on the mount. Having validation of
         * negotiate info for signed connections helps reduce attack vectors
         */
        if (tcon->ses->server->sign == false)
                return 0; /* validation requires signing */

        vneg_inbuf.Capabilities =
                        cpu_to_le32(tcon->ses->server->vals->req_capabilities);
        memcpy(vneg_inbuf.Guid, tcon->ses->server->client_guid,
                                        SMB2_CLIENT_GUID_SIZE);

        if (tcon->ses->sign)
                vneg_inbuf.SecurityMode =
                        cpu_to_le16(SMB2_NEGOTIATE_SIGNING_REQUIRED);
        else if (global_secflags & CIFSSEC_MAY_SIGN)
                vneg_inbuf.SecurityMode =
                        cpu_to_le16(SMB2_NEGOTIATE_SIGNING_ENABLED);
        else
                vneg_inbuf.SecurityMode = 0;

        vneg_inbuf.DialectCount = cpu_to_le16(1);
        vneg_inbuf.Dialects[0] =
                cpu_to_le16(tcon->ses->server->vals->protocol_id);

        rc = SMB2_ioctl(xid, tcon, NO_FILE_ID, NO_FILE_ID,
                FSCTL_VALIDATE_NEGOTIATE_INFO, true /* is_fsctl */,
                (char *)&vneg_inbuf, sizeof(struct validate_negotiate_info_req),
                (char **)&pneg_rsp, &rsplen);

        if (rc != 0) {
                cifs_dbg(VFS, "validate protocol negotiate failed: %d\n", rc);
                return -EIO;
        }

        if (rsplen != sizeof(struct validate_negotiate_info_rsp)) {
                cifs_dbg(VFS, "invalid size of protocol negotiate response\n");
                return -EIO;
        }

        /* check validate negotiate info response matches what we got earlier */
        if (pneg_rsp->Dialect !=
                        cpu_to_le16(tcon->ses->server->vals->protocol_id))
                goto vneg_out;

        if (pneg_rsp->SecurityMode != cpu_to_le16(tcon->ses->server->sec_mode))
                goto vneg_out;

        /* do not validate server guid because not saved at negprot time yet */

        if ((le32_to_cpu(pneg_rsp->Capabilities) | SMB2_NT_FIND |
              SMB2_LARGE_FILES) != tcon->ses->server->capabilities)
                goto vneg_out;

        /* validate negotiate successful */
        cifs_dbg(FYI, "validate negotiate info successful\n");
        return 0;

vneg_out:
        cifs_dbg(VFS, "protocol revalidation - security settings mismatch\n");
        return -EIO;
}

struct SMB2_sess_data {
        unsigned int xid;
        struct cifs_ses *ses;
        struct nls_table *nls_cp;
        void (*func)(struct SMB2_sess_data *);
        int result;
        u64 previous_session;

        /* we will send the SMB in three pieces:
         * a fixed length beginning part, an optional
         * SPNEGO blob (which can be zero length), and a
         * last part which will include the strings
         * and rest of bcc area. This allows us to avoid
         * a large buffer 17K allocation
         */
        int buf0_type;
        struct kvec iov[2];
};

static int
SMB2_sess_alloc_buffer(struct SMB2_sess_data *sess_data)
{
        int rc;
        struct cifs_ses *ses = sess_data->ses;
        struct smb2_sess_setup_req *req;
        struct TCP_Server_Info *server = ses->server;

        rc = small_smb2_init(SMB2_SESSION_SETUP, NULL, (void **) &req);
        if (rc)
                return rc;

        req->hdr.SessionId = 0; /* First session, not a reauthenticate */

        /* if reconnect, we need to send previous sess id, otherwise it is 0 */
        req->PreviousSessionId = sess_data->previous_session;

        req->Flags = 0; /* MBZ */
        /* to enable echos and oplocks */
        req->hdr.CreditRequest = cpu_to_le16(3);

        /* only one of SMB2 signing flags may be set in SMB2 request */
        if (server->sign)
                req->SecurityMode = SMB2_NEGOTIATE_SIGNING_REQUIRED;
        else if (global_secflags & CIFSSEC_MAY_SIGN) /* one flag unlike MUST_ */
                req->SecurityMode = SMB2_NEGOTIATE_SIGNING_ENABLED;
        else
                req->SecurityMode = 0;

        req->Capabilities = 0;
        req->Channel = 0; /* MBZ */

        sess_data->iov[0].iov_base = (char *)req;
        /* 4 for rfc1002 length field and 1 for pad */
        sess_data->iov[0].iov_len = get_rfc1002_length(req) + 4 - 1;
        /*
         * This variable will be used to clear the buffer
         * allocated above in case of any error in the calling function.
         */
        sess_data->buf0_type = CIFS_SMALL_BUFFER;

        return 0;
}

static void
SMB2_sess_free_buffer(struct SMB2_sess_data *sess_data)
{
        free_rsp_buf(sess_data->buf0_type, sess_data->iov[0].iov_base);
        sess_data->buf0_type = CIFS_NO_BUFFER;
}

static int
SMB2_sess_sendreceive(struct SMB2_sess_data *sess_data)
{
        int rc;
        struct smb2_sess_setup_req *req = sess_data->iov[0].iov_base;

        /* Testing shows that buffer offset must be at location of Buffer[0] */
        req->SecurityBufferOffset =
                cpu_to_le16(sizeof(struct smb2_sess_setup_req) -
                        1 /* pad */ - 4 /* rfc1001 len */);
        req->SecurityBufferLength = cpu_to_le16(sess_data->iov[1].iov_len);

        inc_rfc1001_len(req, sess_data->iov[1].iov_len - 1 /* pad */);

        /* BB add code to build os and lm fields */

        rc = SendReceive2(sess_data->xid, sess_data->ses,
                                sess_data->iov, 2,
                                &sess_data->buf0_type,
                                CIFS_LOG_ERROR | CIFS_NEG_OP);

        return rc;
}

static int
SMB2_sess_establish_session(struct SMB2_sess_data *sess_data)
{
        int rc = 0;
        struct cifs_ses *ses = sess_data->ses;

        mutex_lock(&ses->server->srv_mutex);
        if (ses->server->sign && ses->server->ops->generate_signingkey) {
                rc = ses->server->ops->generate_signingkey(ses);
                kfree(ses->auth_key.response);
                ses->auth_key.response = NULL;
                if (rc) {
                        cifs_dbg(FYI,
                                "SMB3 session key generation failed\n");
                        mutex_unlock(&ses->server->srv_mutex);
                        goto keygen_exit;
                }
        }
        if (!ses->server->session_estab) {
                ses->server->sequence_number = 0x2;
                ses->server->session_estab = true;
        }
        mutex_unlock(&ses->server->srv_mutex);

        cifs_dbg(FYI, "SMB2/3 session established successfully\n");
        spin_lock(&GlobalMid_Lock);
        ses->status = CifsGood;
        ses->need_reconnect = false;
        spin_unlock(&GlobalMid_Lock);

keygen_exit:
        if (!ses->server->sign) {
                kfree(ses->auth_key.response);
                ses->auth_key.response = NULL;
        }
        return rc;
}

#ifdef CONFIG_CIFS_UPCALL
static void
SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
{
        int rc;
        struct cifs_ses *ses = sess_data->ses;
        struct cifs_spnego_msg *msg;
        struct key *spnego_key = NULL;
        struct smb2_sess_setup_rsp *rsp = NULL;

        rc = SMB2_sess_alloc_buffer(sess_data);
        if (rc)
                goto out;

        spnego_key = cifs_get_spnego_key(ses);
        if (IS_ERR(spnego_key)) {
                rc = PTR_ERR(spnego_key);
                spnego_key = NULL;
                goto out;
        }

        msg = spnego_key->payload.data;
        /*
         * check version field to make sure that cifs.upcall is
         * sending us a response in an expected form
         */
        if (msg->version != CIFS_SPNEGO_UPCALL_VERSION) {
                cifs_dbg(VFS,
                          "bad cifs.upcall version. Expected %d got %d",
                          CIFS_SPNEGO_UPCALL_VERSION, msg->version);
                rc = -EKEYREJECTED;
                goto out_put_spnego_key;
        }

        ses->auth_key.response = kmemdup(msg->data, msg->sesskey_len,
                                         GFP_KERNEL);
        if (!ses->auth_key.response) {
                cifs_dbg(VFS,
                        "Kerberos can't allocate (%u bytes) memory",
                        msg->sesskey_len);
                rc = -ENOMEM;
                goto out_put_spnego_key;
        }
        ses->auth_key.len = msg->sesskey_len;

        sess_data->iov[1].iov_base = msg->data + msg->sesskey_len;
        sess_data->iov[1].iov_len = msg->secblob_len;

        rc = SMB2_sess_sendreceive(sess_data);
        if (rc)
                goto out_put_spnego_key;

        rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;
        ses->Suid = rsp->hdr.SessionId;

        ses->session_flags = le16_to_cpu(rsp->SessionFlags);
        if (ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA)
                cifs_dbg(VFS, "SMB3 encryption not supported yet\n");

        rc = SMB2_sess_establish_session(sess_data);
out_put_spnego_key:
        key_invalidate(spnego_key);
        key_put(spnego_key);
out:
        sess_data->result = rc;
        sess_data->func = NULL;
        SMB2_sess_free_buffer(sess_data);
}
#else
static void
SMB2_auth_kerberos(struct SMB2_sess_data *sess_data)
{
        cifs_dbg(VFS, "Kerberos negotiated but upcall support disabled!\n");
        sess_data->result = -EOPNOTSUPP;
        sess_data->func = NULL;
}
#endif

static void
SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data);

static void
SMB2_sess_auth_rawntlmssp_negotiate(struct SMB2_sess_data *sess_data)
{
        int rc;
        struct cifs_ses *ses = sess_data->ses;
        struct smb2_sess_setup_rsp *rsp = NULL;
        char *ntlmssp_blob = NULL;
        bool use_spnego = false; /* else use raw ntlmssp */
        u16 blob_length = 0;

        /*
         * If memory allocation is successful, caller of this function
         * frees it.
         */
        ses->ntlmssp = kmalloc(sizeof(struct ntlmssp_auth), GFP_KERNEL);
        if (!ses->ntlmssp) {
                rc = -ENOMEM;
                goto out_err;
        }
        ses->ntlmssp->sesskey_per_smbsess = true;

        rc = SMB2_sess_alloc_buffer(sess_data);
        if (rc)
                goto out_err;

        ntlmssp_blob = kmalloc(sizeof(struct _NEGOTIATE_MESSAGE),
                               GFP_KERNEL);
        if (ntlmssp_blob == NULL) {
                rc = -ENOMEM;
                goto out;
        }

        build_ntlmssp_negotiate_blob(ntlmssp_blob, ses);
        if (use_spnego) {
                /* BB eventually need to add this */
                cifs_dbg(VFS, "spnego not supported for SMB2 yet\n");
                rc = -EOPNOTSUPP;
                goto out;
        } else {
                blob_length = sizeof(struct _NEGOTIATE_MESSAGE);
                /* with raw NTLMSSP we don't encapsulate in SPNEGO */
        }
        sess_data->iov[1].iov_base = ntlmssp_blob;
        sess_data->iov[1].iov_len = blob_length;

        rc = SMB2_sess_sendreceive(sess_data);
        rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;

        /* If true, rc here is expected and not an error */
        if (sess_data->buf0_type != CIFS_NO_BUFFER &&
                rsp->hdr.Status == STATUS_MORE_PROCESSING_REQUIRED)
                rc = 0;

        if (rc)
                goto out;

        if (offsetof(struct smb2_sess_setup_rsp, Buffer) - 4 !=
                        le16_to_cpu(rsp->SecurityBufferOffset)) {
                cifs_dbg(VFS, "Invalid security buffer offset %d\n",
                        le16_to_cpu(rsp->SecurityBufferOffset));
                rc = -EIO;
                goto out;
        }
        rc = decode_ntlmssp_challenge(rsp->Buffer,
                        le16_to_cpu(rsp->SecurityBufferLength), ses);
        if (rc)
                goto out;

        cifs_dbg(FYI, "rawntlmssp session setup challenge phase\n");


        ses->Suid = rsp->hdr.SessionId;
        ses->session_flags = le16_to_cpu(rsp->SessionFlags);
        if (ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA)
                cifs_dbg(VFS, "SMB3 encryption not supported yet\n");

out:
        kfree(ntlmssp_blob);
        SMB2_sess_free_buffer(sess_data);
        if (!rc) {
                sess_data->result = 0;
                sess_data->func = SMB2_sess_auth_rawntlmssp_authenticate;
                return;
        }
out_err:
        kfree(ses->ntlmssp);
        ses->ntlmssp = NULL;
        sess_data->result = rc;
        sess_data->func = NULL;
}

static void
SMB2_sess_auth_rawntlmssp_authenticate(struct SMB2_sess_data *sess_data)
{
        int rc;
        struct cifs_ses *ses = sess_data->ses;
        struct smb2_sess_setup_req *req;
        struct smb2_sess_setup_rsp *rsp = NULL;
        unsigned char *ntlmssp_blob = NULL;
        bool use_spnego = false; /* else use raw ntlmssp */
        u16 blob_length = 0;

        rc = SMB2_sess_alloc_buffer(sess_data);
        if (rc)
                goto out;

        req = (struct smb2_sess_setup_req *) sess_data->iov[0].iov_base;
        req->hdr.SessionId = ses->Suid;

        rc = build_ntlmssp_auth_blob(&ntlmssp_blob, &blob_length, ses,
                                        sess_data->nls_cp);
        if (rc) {
                cifs_dbg(FYI, "build_ntlmssp_auth_blob failed %d\n", rc);
                goto out;
        }

        if (use_spnego) {
                /* BB eventually need to add this */
                cifs_dbg(VFS, "spnego not supported for SMB2 yet\n");
                rc = -EOPNOTSUPP;
                goto out;
        }
        sess_data->iov[1].iov_base = ntlmssp_blob;
        sess_data->iov[1].iov_len = blob_length;

        rc = SMB2_sess_sendreceive(sess_data);
        if (rc)
                goto out;

        rsp = (struct smb2_sess_setup_rsp *)sess_data->iov[0].iov_base;

        ses->Suid = rsp->hdr.SessionId;
        ses->session_flags = le16_to_cpu(rsp->SessionFlags);
        if (ses->session_flags & SMB2_SESSION_FLAG_ENCRYPT_DATA)
                cifs_dbg(VFS, "SMB3 encryption not supported yet\n");

        rc = SMB2_sess_establish_session(sess_data);
out:
        kfree(ntlmssp_blob);
        SMB2_sess_free_buffer(sess_data);
        kfree(ses->ntlmssp);
        ses->ntlmssp = NULL;
        sess_data->result = rc;
        sess_data->func = NULL;
}

static int
SMB2_select_sec(struct cifs_ses *ses, struct SMB2_sess_data *sess_data)
{
        if (ses->sectype != Kerberos && ses->sectype != RawNTLMSSP)
                ses->sectype = RawNTLMSSP;

        switch (ses->sectype) {
        case Kerberos:
                sess_data->func = SMB2_auth_kerberos;
                break;
        case RawNTLMSSP:
                sess_data->func = SMB2_sess_auth_rawntlmssp_negotiate;
                break;
        default:
                cifs_dbg(VFS, "secType %d not supported!\n", ses->sectype);
                return -EOPNOTSUPP;
        }

        return 0;
}

int
SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
                const struct nls_table *nls_cp)
{
        int rc = 0;
        struct TCP_Server_Info *server = ses->server;
        struct SMB2_sess_data *sess_data;

        cifs_dbg(FYI, "Session Setup\n");

        if (!server) {
                WARN(1, "%s: server is NULL!\n", __func__);
                return -EIO;
        }

        sess_data = kzalloc(sizeof(struct SMB2_sess_data), GFP_KERNEL);
        if (!sess_data)
                return -ENOMEM;

        rc = SMB2_select_sec(ses, sess_data);
        if (rc)
                goto out;

        sess_data->xid = xid;
        sess_data->ses = ses;
        sess_data->buf0_type = CIFS_NO_BUFFER;
        sess_data->nls_cp = (struct nls_table *) nls_cp;

        while (sess_data->func)
                sess_data->func(sess_data);

        rc = sess_data->result;
out:
        kfree(sess_data);
        return rc;
}

int
SMB2_logoff(const unsigned int xid, struct cifs_ses *ses)
{
        struct smb2_logoff_req *req; /* response is also trivial struct */
        int rc = 0;
        struct TCP_Server_Info *server;

        cifs_dbg(FYI, "disconnect session %p\n", ses);

        if (ses && (ses->server))
                server = ses->server;
        else
                return -EIO;

        /* no need to send SMB logoff if uid already closed due to reconnect */
        if (ses->need_reconnect)
                goto smb2_session_already_dead;

        rc = small_smb2_init(SMB2_LOGOFF, NULL, (void **) &req);
        if (rc)
                return rc;

         /* since no tcon, smb2_init can not do this, so do here */
        req->hdr.SessionId = ses->Suid;
        if (server->sign)
                req->hdr.Flags |= SMB2_FLAGS_SIGNED;

        rc = SendReceiveNoRsp(xid, ses, (char *) &req->hdr, 0);
        /*
         * No tcon so can't do
         * cifs_stats_inc(&tcon->stats.smb2_stats.smb2_com_fail[SMB2...]);
         */

smb2_session_already_dead:
        return rc;
}

static inline void cifs_stats_fail_inc(struct cifs_tcon *tcon, uint16_t code)
{
        cifs_stats_inc(&tcon->stats.smb2_stats.smb2_com_failed[code]);
}

#define MAX_SHARENAME_LENGTH (255 /* server */ + 80 /* share */ + 1 /* NULL */)

/* These are similar values to what Windows uses */
static inline void init_copy_chunk_defaults(struct cifs_tcon *tcon)
{
        tcon->max_chunks = 256;
        tcon->max_bytes_chunk = 1048576;
        tcon->max_bytes_copy = 16777216;
}

int
SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
          struct cifs_tcon *tcon, const struct nls_table *cp)
{
        struct smb2_tree_connect_req *req;
        struct smb2_tree_connect_rsp *rsp = NULL;
        struct kvec iov[2];
        int rc = 0;
        int resp_buftype;
        int unc_path_len;
        struct TCP_Server_Info *server;
        __le16 *unc_path = NULL;

        cifs_dbg(FYI, "TCON\n");

        if ((ses->server) && tree)
                server = ses->server;
        else
                return -EIO;

        if (tcon && tcon->bad_network_name)
                return -ENOENT;

        if ((tcon && tcon->seal) &&
            ((ses->server->capabilities & SMB2_GLOBAL_CAP_ENCRYPTION) == 0)) {
                cifs_dbg(VFS, "encryption requested but no server support");
                return -EOPNOTSUPP;
        }

        unc_path = kmalloc(MAX_SHARENAME_LENGTH * 2, GFP_KERNEL);
        if (unc_path == NULL)
                return -ENOMEM;

        unc_path_len = cifs_strtoUTF16(unc_path, tree, strlen(tree), cp) + 1;
        unc_path_len *= 2;
        if (unc_path_len < 2) {
                kfree(unc_path);
                return -EINVAL;
        }

        rc = small_smb2_init(SMB2_TREE_CONNECT, tcon, (void **) &req);
        if (rc) {
                kfree(unc_path);
                return rc;
        }

        if (tcon == NULL) {
                /* since no tcon, smb2_init can not do this, so do here */
                req->hdr.SessionId = ses->Suid;
                /* if (ses->server->sec_mode & SECMODE_SIGN_REQUIRED)
                        req->hdr.Flags |= SMB2_FLAGS_SIGNED; */
        }

        iov[0].iov_base = (char *)req;
        /* 4 for rfc1002 length field and 1 for pad */
        iov[0].iov_len = get_rfc1002_length(req) + 4 - 1;

        /* Testing shows that buffer offset must be at location of Buffer[0] */
        req->PathOffset = cpu_to_le16(sizeof(struct smb2_tree_connect_req)
                        - 1 /* pad */ - 4 /* do not count rfc1001 len field */);
        req->PathLength = cpu_to_le16(unc_path_len - 2);
        iov[1].iov_base = unc_path;
        iov[1].iov_len = unc_path_len;

        inc_rfc1001_len(req, unc_path_len - 1 /* pad */);

        rc = SendReceive2(xid, ses, iov, 2, &resp_buftype, 0);
        rsp = (struct smb2_tree_connect_rsp *)iov[0].iov_base;

        if (rc != 0) {
                if (tcon) {
                        cifs_stats_fail_inc(tcon, SMB2_TREE_CONNECT_HE);
                        tcon->need_reconnect = true;
                }
                goto tcon_error_exit;
        }

        if (tcon == NULL) {
                ses->ipc_tid = rsp->hdr.TreeId;
                goto tcon_exit;
        }

        if (rsp->ShareType & SMB2_SHARE_TYPE_DISK)
                cifs_dbg(FYI, "connection to disk share\n");
        else if (rsp->ShareType & SMB2_SHARE_TYPE_PIPE) {
                tcon->ipc = true;
                cifs_dbg(FYI, "connection to pipe share\n");
        } else if (rsp->ShareType & SMB2_SHARE_TYPE_PRINT) {
                tcon->print = true;
                cifs_dbg(FYI, "connection to printer\n");
        } else {
                cifs_dbg(VFS, "unknown share type %d\n", rsp->ShareType);
                rc = -EOPNOTSUPP;
                goto tcon_error_exit;
        }

        tcon->share_flags = le32_to_cpu(rsp->ShareFlags);
        tcon->capabilities = rsp->Capabilities; /* we keep caps little endian */
        tcon->maximal_access = le32_to_cpu(rsp->MaximalAccess);
        tcon->tidStatus = CifsGood;
        tcon->need_reconnect = false;
        tcon->tid = rsp->hdr.TreeId;
        strlcpy(tcon->treeName, tree, sizeof(tcon->treeName));

        if ((rsp->Capabilities & SMB2_SHARE_CAP_DFS) &&
            ((tcon->share_flags & SHI1005_FLAGS_DFS) == 0))
                cifs_dbg(VFS, "DFS capability contradicts DFS flag\n");
        init_copy_chunk_defaults(tcon);
        if (tcon->share_flags & SHI1005_FLAGS_ENCRYPT_DATA)
                cifs_dbg(VFS, "Encrypted shares not supported");
        if (tcon->ses->server->ops->validate_negotiate)
                rc = tcon->ses->server->ops->validate_negotiate(xid, tcon);
tcon_exit:
        free_rsp_buf(resp_buftype, rsp);
        kfree(unc_path);
        return rc;

tcon_error_exit:
        if (rsp->hdr.Status == STATUS_BAD_NETWORK_NAME) {
                cifs_dbg(VFS, "BAD_NETWORK_NAME: %s\n", tree);
                if (tcon)
                        tcon->bad_network_name = true;
        }
        goto tcon_exit;
}

int
SMB2_tdis(const unsigned int xid, struct cifs_tcon *tcon)
{
        struct smb2_tree_disconnect_req *req; /* response is trivial */
        int rc = 0;
        struct TCP_Server_Info *server;
        struct cifs_ses *ses = tcon->ses;

        cifs_dbg(FYI, "Tree Disconnect\n");

        if (ses && (ses->server))
                server = ses->server;
        else
                return -EIO;

        if ((tcon->need_reconnect) || (tcon->ses->need_reconnect))
                return 0;

        rc = small_smb2_init(SMB2_TREE_DISCONNECT, tcon, (void **) &req);
        if (rc)
                return rc;

        rc = SendReceiveNoRsp(xid, ses, (char *)&req->hdr, 0);
        if (rc)
                cifs_stats_fail_inc(tcon, SMB2_TREE_DISCONNECT_HE);

        return rc;
}


static struct create_durable *
create_durable_buf(void)
{
        struct create_durable *buf;

        buf = kzalloc(sizeof(struct create_durable), GFP_KERNEL);
        if (!buf)
                return NULL;

        buf->ccontext.DataOffset = cpu_to_le16(offsetof
                                        (struct create_durable, Data));
        buf->ccontext.DataLength = cpu_to_le32(16);
        buf->ccontext.NameOffset = cpu_to_le16(offsetof
                                (struct create_durable, Name));
        buf->ccontext.NameLength = cpu_to_le16(4);
        /* SMB2_CREATE_DURABLE_HANDLE_REQUEST is "DHnQ" */
        buf->Name[0] = 'D';
        buf->Name[1] = 'H';
        buf->Name[2] = 'n';
        buf->Name[3] = 'Q';
        return buf;
}

static struct create_durable *
create_reconnect_durable_buf(struct cifs_fid *fid)
{
        struct create_durable *buf;

        buf = kzalloc(sizeof(struct create_durable), GFP_KERNEL);
        if (!buf)
                return NULL;

        buf->ccontext.DataOffset = cpu_to_le16(offsetof
                                        (struct create_durable, Data));
        buf->ccontext.DataLength = cpu_to_le32(16);
        buf->ccontext.NameOffset = cpu_to_le16(offsetof
                                (struct create_durable, Name));
        buf->ccontext.NameLength = cpu_to_le16(4);
        buf->Data.Fid.PersistentFileId = fid->persistent_fid;
        buf->Data.Fid.VolatileFileId = fid->volatile_fid;
        /* SMB2_CREATE_DURABLE_HANDLE_RECONNECT is "DHnC" */
        buf->Name[0] = 'D';
        buf->Name[1] = 'H';
        buf->Name[2] = 'n';
        buf->Name[3] = 'C';
        return buf;
}

static __u8
parse_lease_state(struct TCP_Server_Info *server, struct smb2_create_rsp *rsp,
                  unsigned int *epoch)
{
        char *data_offset;
        struct create_context *cc;
        unsigned int next;
        unsigned int remaining;
        char *name;

        data_offset = (char *)rsp + 4 + le32_to_cpu(rsp->CreateContextsOffset);
        remaining = le32_to_cpu(rsp->CreateContextsLength);
        cc = (struct create_context *)data_offset;
        while (remaining >= sizeof(struct create_context)) {
                name = le16_to_cpu(cc->NameOffset) + (char *)cc;
                if (le16_to_cpu(cc->NameLength) == 4 &&
                    strncmp(name, "RqLs", 4) == 0)
                        return server->ops->parse_lease_buf(cc, epoch);

                next = le32_to_cpu(cc->Next);
                if (!next)
                        break;
                remaining -= next;
                cc = (struct create_context *)((char *)cc + next);
        }

        return 0;
}

static int
add_lease_context(struct TCP_Server_Info *server, struct kvec *iov,
                  unsigned int *num_iovec, __u8 *oplock)
{
        struct smb2_create_req *req = iov[0].iov_base;
        unsigned int num = *num_iovec;

        iov[num].iov_base = server->ops->create_lease_buf(oplock+1, *oplock);
        if (iov[num].iov_base == NULL)
                return -ENOMEM;
        iov[num].iov_len = server->vals->create_lease_size;
        req->RequestedOplockLevel = SMB2_OPLOCK_LEVEL_LEASE;
        if (!req->CreateContextsOffset)
                req->CreateContextsOffset = cpu_to_le32(
                                sizeof(struct smb2_create_req) - 4 +
                                iov[num - 1].iov_len);
        le32_add_cpu(&req->CreateContextsLength,
                     server->vals->create_lease_size);
        inc_rfc1001_len(&req->hdr, server->vals->create_lease_size);
        *num_iovec = num + 1;
        return 0;
}

static struct create_durable_v2 *
create_durable_v2_buf(struct cifs_fid *pfid)
{
        struct create_durable_v2 *buf;

        buf = kzalloc(sizeof(struct create_durable_v2), GFP_KERNEL);
        if (!buf)
                return NULL;

        buf->ccontext.DataOffset = cpu_to_le16(offsetof
                                        (struct create_durable_v2, dcontext));
        buf->ccontext.DataLength = cpu_to_le32(sizeof(struct durable_context_v2));
        buf->ccontext.NameOffset = cpu_to_le16(offsetof
                                (struct create_durable_v2, Name));
        buf->ccontext.NameLength = cpu_to_le16(4);

        buf->dcontext.Timeout = 0; /* Should this be configurable by workload */
        buf->dcontext.Flags = cpu_to_le32(SMB2_DHANDLE_FLAG_PERSISTENT);
        generate_random_uuid(buf->dcontext.CreateGuid);
        memcpy(pfid->create_guid, buf->dcontext.CreateGuid, 16);

        /* SMB2_CREATE_DURABLE_HANDLE_REQUEST is "DH2Q" */
        buf->Name[0] = 'D';
        buf->Name[1] = 'H';
        buf->Name[2] = '2';
        buf->Name[3] = 'Q';
        return buf;
}

static struct create_durable_handle_reconnect_v2 *
create_reconnect_durable_v2_buf(struct cifs_fid *fid)
{
        struct create_durable_handle_reconnect_v2 *buf;

        buf = kzalloc(sizeof(struct create_durable_handle_reconnect_v2),
                        GFP_KERNEL);
        if (!buf)
                return NULL;

        buf->ccontext.DataOffset =
                cpu_to_le16(offsetof(struct create_durable_handle_reconnect_v2,
                                     dcontext));
        buf->ccontext.DataLength =
                cpu_to_le32(sizeof(struct durable_reconnect_context_v2));
        buf->ccontext.NameOffset =
                cpu_to_le16(offsetof(struct create_durable_handle_reconnect_v2,
                            Name));
        buf->ccontext.NameLength = cpu_to_le16(4);

        buf->dcontext.Fid.PersistentFileId = fid->persistent_fid;
        buf->dcontext.Fid.VolatileFileId = fid->volatile_fid;
        buf->dcontext.Flags = cpu_to_le32(SMB2_DHANDLE_FLAG_PERSISTENT);
        memcpy(buf->dcontext.CreateGuid, fid->create_guid, 16);

        /* SMB2_CREATE_DURABLE_HANDLE_RECONNECT_V2 is "DH2C" */
        buf->Name[0] = 'D';
        buf->Name[1] = 'H';
        buf->Name[2] = '2';
        buf->Name[3] = 'C';
        return buf;
}

static int
add_durable_v2_context(struct kvec *iov, unsigned int *num_iovec,
                    struct cifs_open_parms *oparms)
{
        struct smb2_create_req *req = iov[0].iov_base;
        unsigned int num = *num_iovec;

        iov[num].iov_base = create_durable_v2_buf(oparms->fid);
        if (iov[num].iov_base == NULL)
                return -ENOMEM;
        iov[num].iov_len = sizeof(struct create_durable_v2);
        if (!req->CreateContextsOffset)
                req->CreateContextsOffset =
                        cpu_to_le32(sizeof(struct smb2_create_req) - 4 +
                                                                iov[1].iov_len);
        le32_add_cpu(&req->CreateContextsLength, sizeof(struct create_durable_v2));
        inc_rfc1001_len(&req->hdr, sizeof(struct create_durable_v2));
        *num_iovec = num + 1;
        return 0;
}

static int
add_durable_reconnect_v2_context(struct kvec *iov, unsigned int *num_iovec,
                    struct cifs_open_parms *oparms)
{
        struct smb2_create_req *req = iov[0].iov_base;
        unsigned int num = *num_iovec;

        /* indicate that we don't need to relock the file */
        oparms->reconnect = false;

        iov[num].iov_base = create_reconnect_durable_v2_buf(oparms->fid);
        if (iov[num].iov_base == NULL)
                return -ENOMEM;
        iov[num].iov_len = sizeof(struct create_durable_handle_reconnect_v2);
        if (!req->CreateContextsOffset)
                req->CreateContextsOffset =
                        cpu_to_le32(sizeof(struct smb2_create_req) - 4 +
                                                                iov[1].iov_len);
        le32_add_cpu(&req->CreateContextsLength,
                        sizeof(struct create_durable_handle_reconnect_v2));
        inc_rfc1001_len(&req->hdr,
                        sizeof(struct create_durable_handle_reconnect_v2));
        *num_iovec = num + 1;
        return 0;
}

static int
add_durable_context(struct kvec *iov, unsigned int *num_iovec,
                    struct cifs_open_parms *oparms, bool use_persistent)
{
        struct smb2_create_req *req = iov[0].iov_base;
        unsigned int num = *num_iovec;

        if (use_persistent) {
                if (oparms->reconnect)
                        return add_durable_reconnect_v2_context(iov, num_iovec,
                                                                oparms);
                else
                        return add_durable_v2_context(iov, num_iovec, oparms);
        }

        if (oparms->reconnect) {
                iov[num].iov_base = create_reconnect_durable_buf(oparms->fid);
                /* indicate that we don't need to relock the file */
                oparms->reconnect = false;
        } else
                iov[num].iov_base = create_durable_buf();
        if (iov[num].iov_base == NULL)
                return -ENOMEM;
        iov[num].iov_len = sizeof(struct create_durable);
        if (!req->CreateContextsOffset)
                req->CreateContextsOffset =
                        cpu_to_le32(sizeof(struct smb2_create_req) - 4 +
                                                                iov[1].iov_len);
        le32_add_cpu(&req->CreateContextsLength, sizeof(struct create_durable));
        inc_rfc1001_len(&req->hdr, sizeof(struct create_durable));
        *num_iovec = num + 1;
        return 0;
}

int
SMB2_open(const unsigned int xid, struct cifs_open_parms *oparms, __le16 *path,
          __u8 *oplock, struct smb2_file_all_info *buf,
          struct smb2_err_rsp **err_buf)
{
        struct smb2_create_req *req;
        struct smb2_create_rsp *rsp;
        struct TCP_Server_Info *server;
        struct cifs_tcon *tcon = oparms->tcon;
        struct cifs_ses *ses = tcon->ses;
        struct kvec iov[4];
        int resp_buftype;
        int uni_path_len;
        __le16 *copy_path = NULL;
        int copy_size;
        int rc = 0;
        unsigned int num_iovecs = 2;
        __u32 file_attributes = 0;
        char *dhc_buf = NULL, *lc_buf = NULL;

        cifs_dbg(FYI, "create/open\n");

        if (ses && (ses->server))
                server = ses->server;
        else
                return -EIO;

        rc = small_smb2_init(SMB2_CREATE, tcon, (void **) &req);
        if (rc)
                return rc;

        if (oparms->create_options & CREATE_OPTION_READONLY)
                file_attributes |= ATTR_READONLY;
        if (oparms->create_options & CREATE_OPTION_SPECIAL)
                file_attributes |= ATTR_SYSTEM;

        req->ImpersonationLevel = IL_IMPERSONATION;
        req->DesiredAccess = cpu_to_le32(oparms->desired_access);
        /* File attributes ignored on open (used in create though) */
        req->FileAttributes = cpu_to_le32(file_attributes);
        req->ShareAccess = FILE_SHARE_ALL_LE;
        req->CreateDisposition = cpu_to_le32(oparms->disposition);
        req->CreateOptions = cpu_to_le32(oparms->create_options & CREATE_OPTIONS_MASK);
        uni_path_len = (2 * UniStrnlen((wchar_t *)path, PATH_MAX)) + 2;
        /* do not count rfc1001 len field */
        req->NameOffset = cpu_to_le16(sizeof(struct smb2_create_req) - 4);

        iov[0].iov_base = (char *)req;
        /* 4 for rfc1002 length field */
        iov[0].iov_len = get_rfc1002_length(req) + 4;

        /* MUST set path len (NameLength) to 0 opening root of share */
        req->NameLength = cpu_to_le16(uni_path_len - 2);
        /* -1 since last byte is buf[0] which is sent below (path) */
        iov[0].iov_len--;
        if (uni_path_len % 8 != 0) {
                copy_size = uni_path_len / 8 * 8;
                if (copy_size < uni_path_len)
                        copy_size += 8;

                copy_path = kzalloc(copy_size, GFP_KERNEL);
                if (!copy_path)
                        return -ENOMEM;
                memcpy((char *)copy_path, (const char *)path,
                        uni_path_len);
                uni_path_len = copy_size;
                path = copy_path;
        }

        iov[1].iov_len = uni_path_len;
        iov[1].iov_base = path;
        /* -1 since last byte is buf[0] which was counted in smb2_buf_len */
        inc_rfc1001_len(req, uni_path_len - 1);

        if (!server->oplocks)
                *oplock = SMB2_OPLOCK_LEVEL_NONE;

        if (!(server->capabilities & SMB2_GLOBAL_CAP_LEASING) ||
            *oplock == SMB2_OPLOCK_LEVEL_NONE)
                req->RequestedOplockLevel = *oplock;
        else {
                rc = add_lease_context(server, iov, &num_iovecs, oplock);
                if (rc) {
                        cifs_small_buf_release(req);
                        kfree(copy_path);
                        return rc;
                }
                lc_buf = iov[num_iovecs-1].iov_base;
        }

        if (*oplock == SMB2_OPLOCK_LEVEL_BATCH) {
                /* need to set Next field of lease context if we request it */
                if (server->capabilities & SMB2_GLOBAL_CAP_LEASING) {
                        struct create_context *ccontext =
                            (struct create_context *)iov[num_iovecs-1].iov_base;
                        ccontext->Next =
                                cpu_to_le32(server->vals->create_lease_size);
                }

                rc = add_durable_context(iov, &num_iovecs, oparms,
                                        tcon->use_persistent);
                if (rc) {
                        cifs_small_buf_release(req);
                        kfree(copy_path);
                        kfree(lc_buf);
                        return rc;
                }
                dhc_buf = iov[num_iovecs-1].iov_base;
        }

        rc = SendReceive2(xid, ses, iov, num_iovecs, &resp_buftype, 0);
        rsp = (struct smb2_create_rsp *)iov[0].iov_base;

        if (rc != 0) {
                cifs_stats_fail_inc(tcon, SMB2_CREATE_HE);
                if (err_buf)
                        *err_buf = kmemdup(rsp, get_rfc1002_length(rsp) + 4,
                                           GFP_KERNEL);
                goto creat_exit;
        }

        oparms->fid->persistent_fid = rsp->PersistentFileId;
        oparms->fid->volatile_fid = rsp->VolatileFileId;

        if (buf) {
                memcpy(buf, &rsp->CreationTime, 32);
                buf->AllocationSize = rsp->AllocationSize;
                buf->EndOfFile = rsp->EndofFile;
                buf->Attributes = rsp->FileAttributes;
                buf->NumberOfLinks = cpu_to_le32(1);
                buf->DeletePending = 0;
        }

        if (rsp->OplockLevel == SMB2_OPLOCK_LEVEL_LEASE)
                *oplock = parse_lease_state(server, rsp, &oparms->fid->epoch);
        else
                *oplock = rsp->OplockLevel;
creat_exit:
        kfree(copy_path);
        kfree(lc_buf);
        kfree(dhc_buf);
        free_rsp_buf(resp_buftype, rsp);
        return rc;
}

/*
 *      SMB2 IOCTL is used for both IOCTLs and FSCTLs
 */
int
SMB2_ioctl(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
           u64 volatile_fid, u32 opcode, bool is_fsctl, char *in_data,
           u32 indatalen, char **out_data, u32 *plen /* returned data len */)
{
        struct smb2_ioctl_req *req;
        struct smb2_ioctl_rsp *rsp;
        struct TCP_Server_Info *server;
        struct cifs_ses *ses;
        struct kvec iov[2];
        int resp_buftype;
        int num_iovecs;
        int rc = 0;

        cifs_dbg(FYI, "SMB2 IOCTL\n");

        if (out_data != NULL)
                *out_data = NULL;

        /* zero out returned data len, in case of error */
        if (plen)
                *plen = 0;

        if (tcon)
                ses = tcon->ses;
        else
                return -EIO;

        if (ses && (ses->server))
                server = ses->server;
        else
                return -EIO;

        rc = small_smb2_init(SMB2_IOCTL, tcon, (void **) &req);
        if (rc)
                return rc;

        req->CtlCode = cpu_to_le32(opcode);
        req->PersistentFileId = persistent_fid;
        req->VolatileFileId = volatile_fid;

        if (indatalen) {
                req->InputCount = cpu_to_le32(indatalen);
                /* do not set InputOffset if no input data */
                req->InputOffset =
                       cpu_to_le32(offsetof(struct smb2_ioctl_req, Buffer) - 4);
                iov[1].iov_base = in_data;
                iov[1].iov_len = indatalen;
                num_iovecs = 2;
        } else
                num_iovecs = 1;

        req->OutputOffset = 0;
        req->OutputCount = 0; /* MBZ */

        /*
         * Could increase MaxOutputResponse, but that would require more
         * than one credit. Windows typically sets this smaller, but for some
         * ioctls it may be useful to allow server to send more. No point
         * limiting what the server can send as long as fits in one credit
         */
        req->MaxOutputResponse = cpu_to_le32(0xFF00); /* < 64K uses 1 credit */

        if (is_fsctl)
                req->Flags = cpu_to_le32(SMB2_0_IOCTL_IS_FSCTL);
        else
                req->Flags = 0;

        iov[0].iov_base = (char *)req;

        /*
         * If no input data, the size of ioctl struct in
         * protocol spec still includes a 1 byte data buffer,
         * but if input data passed to ioctl, we do not
         * want to double count this, so we do not send
         * the dummy one byte of data in iovec[0] if sending
         * input data (in iovec[1]). We also must add 4 bytes
         * in first iovec to allow for rfc1002 length field.
         */

        if (indatalen) {
                iov[0].iov_len = get_rfc1002_length(req) + 4 - 1;
                inc_rfc1001_len(req, indatalen - 1);
        } else
                iov[0].iov_len = get_rfc1002_length(req) + 4;


        rc = SendReceive2(xid, ses, iov, num_iovecs, &resp_buftype, 0);
        rsp = (struct smb2_ioctl_rsp *)iov[0].iov_base;

        if ((rc != 0) && (rc != -EINVAL)) {
                cifs_stats_fail_inc(tcon, SMB2_IOCTL_HE);
                goto ioctl_exit;
        } else if (rc == -EINVAL) {
                if ((opcode != FSCTL_SRV_COPYCHUNK_WRITE) &&
                    (opcode != FSCTL_SRV_COPYCHUNK)) {
                        cifs_stats_fail_inc(tcon, SMB2_IOCTL_HE);
                        goto ioctl_exit;
                }
        }

        /* check if caller wants to look at return data or just return rc */
        if ((plen == NULL) || (out_data == NULL))
                goto ioctl_exit;

        *plen = le32_to_cpu(rsp->OutputCount);

        /* We check for obvious errors in the output buffer length and offset */
        if (*plen == 0)
                goto ioctl_exit; /* server returned no data */
        else if (*plen > 0xFF00) {
                cifs_dbg(VFS, "srv returned invalid ioctl length: %d\n", *plen);
                *plen = 0;
                rc = -EIO;
                goto ioctl_exit;
        }

        if (get_rfc1002_length(rsp) < le32_to_cpu(rsp->OutputOffset) + *plen) {
                cifs_dbg(VFS, "Malformed ioctl resp: len %d offset %d\n", *plen,
                        le32_to_cpu(rsp->OutputOffset));
                *plen = 0;
                rc = -EIO;
                goto ioctl_exit;
        }

        *out_data = kmalloc(*plen, GFP_KERNEL);
        if (*out_data == NULL) {
                rc = -ENOMEM;
                goto ioctl_exit;
        }

        memcpy(*out_data,
               (char *)&rsp->hdr.ProtocolId + le32_to_cpu(rsp->OutputOffset),
               *plen);
ioctl_exit:
        free_rsp_buf(resp_buftype, rsp);
        return rc;
}

/*
 *   Individual callers to ioctl worker function follow
 */

int
SMB2_set_compression(const unsigned int xid, struct cifs_tcon *tcon,
                     u64 persistent_fid, u64 volatile_fid)
{
        int rc;
        struct  compress_ioctl fsctl_input;
        char *ret_data = NULL;

        fsctl_input.CompressionState =
                        cpu_to_le16(COMPRESSION_FORMAT_DEFAULT);

        rc = SMB2_ioctl(xid, tcon, persistent_fid, volatile_fid,
                        FSCTL_SET_COMPRESSION, true /* is_fsctl */,
                        (char *)&fsctl_input /* data input */,
                        2 /* in data len */, &ret_data /* out data */, NULL);

        cifs_dbg(FYI, "set compression rc %d\n", rc);

        return rc;
}

int
SMB2_close(const unsigned int xid, struct cifs_tcon *tcon,
           u64 persistent_fid, u64 volatile_fid)
{
        struct smb2_close_req *req;
        struct smb2_close_rsp *rsp;
        struct TCP_Server_Info *server;
        struct cifs_ses *ses = tcon->ses;
        struct kvec iov[1];
        int resp_buftype;
        int rc = 0;

        cifs_dbg(FYI, "Close\n");

        if (ses && (ses->server))
                server = ses->server;
        else
                return -EIO;

        rc = small_smb2_init(SMB2_CLOSE, tcon, (void **) &req);
        if (rc)
                return rc;

        req->PersistentFileId = persistent_fid;
        req->VolatileFileId = volatile_fid;

        iov[0].iov_base = (char *)req;
        /* 4 for rfc1002 length field */
        iov[0].iov_len = get_rfc1002_length(req) + 4;

        rc = SendReceive2(xid, ses, iov, 1, &resp_buftype, 0);
        rsp = (struct smb2_close_rsp *)iov[0].iov_base;

        if (rc != 0) {
                cifs_stats_fail_inc(tcon, SMB2_CLOSE_HE);
                goto close_exit;
        }

        /* BB FIXME - decode close response, update inode for caching */

close_exit:
        free_rsp_buf(resp_buftype, rsp);
        return rc;
}

static int
validate_buf(unsigned int offset, unsigned int buffer_length,
             struct smb2_hdr *hdr, unsigned int min_buf_size)

{
        unsigned int smb_len = be32_to_cpu(hdr->smb2_buf_length);
        char *end_of_smb = smb_len + 4 /* RFC1001 length field */ + (char *)hdr;
        char *begin_of_buf = 4 /* RFC1001 len field */ + offset + (char *)hdr;
        char *end_of_buf = begin_of_buf + buffer_length;


        if (buffer_length < min_buf_size) {
                cifs_dbg(VFS, "buffer length %d smaller than minimum size %d\n",
                         buffer_length, min_buf_size);
                return -EINVAL;
        }

        /* check if beyond RFC1001 maximum length */
        if ((smb_len > 0x7FFFFF) || (buffer_length > 0x7FFFFF)) {
                cifs_dbg(VFS, "buffer length %d or smb length %d too large\n",
                         buffer_length, smb_len);
                return -EINVAL;
        }

        if ((begin_of_buf > end_of_smb) || (end_of_buf > end_of_smb)) {
                cifs_dbg(VFS, "illegal server response, bad offset to data\n");
                return -EINVAL;
        }

        return 0;
}

/*
 * If SMB buffer fields are valid, copy into temporary buffer to hold result.
 * Caller must free buffer.
 */
static int
validate_and_copy_buf(unsigned int offset, unsigned int buffer_length,
                      struct smb2_hdr *hdr, unsigned int minbufsize,
                      char *data)

{
        char *begin_of_buf = 4 /* RFC1001 len field */ + offset + (char *)hdr;
        int rc;

        if (!data)
                return -EINVAL;

        rc = validate_buf(offset, buffer_length, hdr, minbufsize);
        if (rc)
                return rc;

        memcpy(data, begin_of_buf, buffer_length);

        return 0;
}

static int
query_info(const unsigned int xid, struct cifs_tcon *tcon,
           u64 persistent_fid, u64 volatile_fid, u8 info_class,
           size_t output_len, size_t min_len, void *data)
{
        struct smb2_query_info_req *req;
        struct smb2_query_info_rsp *rsp = NULL;
        struct kvec iov[2];
        int rc = 0;
        int resp_buftype;
        struct TCP_Server_Info *server;
        struct cifs_ses *ses = tcon->ses;

        cifs_dbg(FYI, "Query Info\n");

        if (ses && (ses->server))
                server = ses->server;
        else
                return -EIO;

        rc = small_smb2_init(SMB2_QUERY_INFO, tcon, (void **) &req);
        if (rc)
                return rc;

        req->InfoType = SMB2_O_INFO_FILE;
        req->FileInfoClass = info_class;
        req->PersistentFileId = persistent_fid;
        req->VolatileFileId = volatile_fid;
        /* 4 for rfc1002 length field and 1 for Buffer */
        req->InputBufferOffset =
                cpu_to_le16(sizeof(struct smb2_query_info_req) - 1 - 4);
        req->OutputBufferLength = cpu_to_le32(output_len);

        iov[0].iov_base = (char *)req;
        /* 4 for rfc1002 length field */
        iov[0].iov_len = get_rfc1002_length(req) + 4;

        rc = SendReceive2(xid, ses, iov, 1, &resp_buftype, 0);
        rsp = (struct smb2_query_info_rsp *)iov[0].iov_base;

        if (rc) {
                cifs_stats_fail_inc(tcon, SMB2_QUERY_INFO_HE);
                goto qinf_exit;
        }

        rc = validate_and_copy_buf(le16_to_cpu(rsp->OutputBufferOffset),
                                   le32_to_cpu(rsp->OutputBufferLength),
                                   &rsp->hdr, min_len, data);

qinf_exit:
        free_rsp_buf(resp_buftype, rsp);
        return rc;
}

int
SMB2_query_info(const unsigned int xid, struct cifs_tcon *tcon,
                u64 persistent_fid, u64 volatile_fid,
                struct smb2_file_all_info *data)
{
        return query_info(xid, tcon, persistent_fid, volatile_fid,
                          FILE_ALL_INFORMATION,
                          sizeof(struct smb2_file_all_info) + PATH_MAX * 2,
                          sizeof(struct smb2_file_all_info), data);
}

int
SMB2_get_srv_num(const unsigned int xid, struct cifs_tcon *tcon,
                 u64 persistent_fid, u64 volatile_fid, __le64 *uniqueid)
{
        return query_info(xid, tcon, persistent_fid, volatile_fid,
                          FILE_INTERNAL_INFORMATION,
                          sizeof(struct smb2_file_internal_info),
                          sizeof(struct smb2_file_internal_info), uniqueid);
}

/*
 * This is a no-op for now. We're not really interested in the reply, but
 * rather in the fact that the server sent one and that server->lstrp
 * gets updated.
 *
 * FIXME: maybe we should consider checking that the reply matches request?
 */
static void
smb2_echo_callback(struct mid_q_entry *mid)
{
        struct TCP_Server_Info *server = mid->callback_data;
        struct smb2_echo_rsp *smb2 = (struct smb2_echo_rsp *)mid->resp_buf;
        unsigned int credits_received = 1;

        if (mid->mid_state == MID_RESPONSE_RECEIVED)
                credits_received = le16_to_cpu(smb2->hdr.CreditRequest);

        mutex_lock(&server->srv_mutex);
        DeleteMidQEntry(mid);
        mutex_unlock(&server->srv_mutex);
        add_credits(server, credits_received, CIFS_ECHO_OP);
}

void smb2_reconnect_server(struct work_struct *work)
{
        struct TCP_Server_Info *server = container_of(work,
                                        struct TCP_Server_Info, reconnect.work);
        struct cifs_ses *ses;
        struct cifs_tcon *tcon, *tcon2;
        struct list_head tmp_list;
        int tcon_exist = false;

        /* Prevent simultaneous reconnects that can corrupt tcon->rlist list */
        mutex_lock(&server->reconnect_mutex);

        INIT_LIST_HEAD(&tmp_list);
        cifs_dbg(FYI, "Need negotiate, reconnecting tcons\n");

        spin_lock(&cifs_tcp_ses_lock);
        list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
                list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {
                        if (tcon->need_reconnect || tcon->need_reopen_files) {
                                tcon->tc_count++;
                                list_add_tail(&tcon->rlist, &tmp_list);
                                tcon_exist = true;
                        }

                }
        }
        /*
         * Get the reference to server struct to be sure that the last call of
         * cifs_put_tcon() in the loop below won't release the server pointer.
         */
        if (tcon_exist)
                server->srv_count++;

        spin_unlock(&cifs_tcp_ses_lock);

        list_for_each_entry_safe(tcon, tcon2, &tmp_list, rlist) {
                if (!smb2_reconnect(SMB2_INTERNAL_CMD, tcon))
                        cifs_reopen_persistent_handles(tcon);
                list_del_init(&tcon->rlist);
                cifs_put_tcon(tcon);
        }

        cifs_dbg(FYI, "Reconnecting tcons finished\n");
        mutex_unlock(&server->reconnect_mutex);

        /* now we can safely release srv struct */
        if (tcon_exist)
                cifs_put_tcp_session(server, 1);
}

int
SMB2_echo(struct TCP_Server_Info *server)
{
        struct smb2_echo_req *req;
        int rc = 0;
        struct kvec iov;
        struct smb_rqst rqst = { .rq_iov = &iov,
                                 .rq_nvec = 1 };

        cifs_dbg(FYI, "In echo request\n");

        if (server->tcpStatus == CifsNeedNegotiate) {
                /* No need to send echo on newly established connections */
                queue_delayed_work(cifsiod_wq, &server->reconnect, 0);
                return rc;
        }

        rc = small_smb2_init(SMB2_ECHO, NULL, (void **)&req);
        if (rc)
                return rc;

        req->hdr.CreditRequest = cpu_to_le16(1);

        iov.iov_base = (char *)req;
        /* 4 for rfc1002 length field */
        iov.iov_len = get_rfc1002_length(req) + 4;

        rc = cifs_call_async(server, &rqst, NULL, smb2_echo_callback, server,
                             CIFS_ECHO_OP);
        if (rc)
                cifs_dbg(FYI, "Echo request failed: %d\n", rc);

        cifs_small_buf_release(req);
        return rc;
}

int
SMB2_flush(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
           u64 volatile_fid)
{
        struct smb2_flush_req *req;
        struct TCP_Server_Info *server;
        struct cifs_ses *ses = tcon->ses;
        struct kvec iov[1];
        int resp_buftype;
        int rc = 0;

        cifs_dbg(FYI, "Flush\n");

        if (ses && (ses->server))
                server = ses->server;
        else
                return -EIO;

        rc = small_smb2_init(SMB2_FLUSH, tcon, (void **) &req);
        if (rc)
                return rc;

        req->PersistentFileId = persistent_fid;
        req->VolatileFileId = volatile_fid;

        iov[0].iov_base = (char *)req;
        /* 4 for rfc1002 length field */
        iov[0].iov_len = get_rfc1002_length(req) + 4;

        rc = SendReceive2(xid, ses, iov, 1, &resp_buftype, 0);

        if (rc != 0)
                cifs_stats_fail_inc(tcon, SMB2_FLUSH_HE);

        free_rsp_buf(resp_buftype, iov[0].iov_base);
        return rc;
}

/*
 * To form a chain of read requests, any read requests after the first should
 * have the end_of_chain boolean set to true.
 */
static int
smb2_new_read_req(struct kvec *iov, struct cifs_io_parms *io_parms,
                  unsigned int remaining_bytes, int request_type)
{
        int rc = -EACCES;
        struct smb2_read_req *req = NULL;

        rc = small_smb2_init(SMB2_READ, io_parms->tcon, (void **) &req);
        if (rc)
                return rc;
        if (io_parms->tcon->ses->server == NULL)
                return -ECONNABORTED;

        req->hdr.ProcessId = cpu_to_le32(io_parms->pid);

        req->PersistentFileId = io_parms->persistent_fid;
        req->VolatileFileId = io_parms->volatile_fid;
        req->ReadChannelInfoOffset = 0; /* reserved */
        req->ReadChannelInfoLength = 0; /* reserved */
        req->Channel = 0; /* reserved */
        req->MinimumCount = 0;
        req->Length = cpu_to_le32(io_parms->length);
        req->Offset = cpu_to_le64(io_parms->offset);

        if (request_type & CHAINED_REQUEST) {
                if (!(request_type & END_OF_CHAIN)) {
                        /* 4 for rfc1002 length field */
                        req->hdr.NextCommand =
                                cpu_to_le32(get_rfc1002_length(req) + 4);
                } else /* END_OF_CHAIN */
                        req->hdr.NextCommand = 0;
                if (request_type & RELATED_REQUEST) {
                        req->hdr.Flags |= SMB2_FLAGS_RELATED_OPERATIONS;
                        /*
                         * Related requests use info from previous read request
                         * in chain.
                         */
                        req->hdr.SessionId = 0xFFFFFFFF;
                        req->hdr.TreeId = 0xFFFFFFFF;
                        req->PersistentFileId = 0xFFFFFFFF;
                        req->VolatileFileId = 0xFFFFFFFF;
                }
        }
        if (remaining_bytes > io_parms->length)
                req->RemainingBytes = cpu_to_le32(remaining_bytes);
        else
                req->RemainingBytes = 0;

        iov[0].iov_base = (char *)req;
        /* 4 for rfc1002 length field */
        iov[0].iov_len = get_rfc1002_length(req) + 4;
        return rc;
}

static void
smb2_readv_callback(struct mid_q_entry *mid)
{
        struct cifs_readdata *rdata = mid->callback_data;
        struct cifs_tcon *tcon = tlink_tcon(rdata->cfile->tlink);
        struct TCP_Server_Info *server = tcon->ses->server;
        struct smb2_hdr *buf = (struct smb2_hdr *)rdata->iov.iov_base;
        unsigned int credits_received = 1;
        struct smb_rqst rqst = { .rq_iov = &rdata->iov,
                                 .rq_nvec = 1,
                                 .rq_pages = rdata->pages,
                                 .rq_npages = rdata->nr_pages,
                                 .rq_pagesz = rdata->pagesz,
                                 .rq_tailsz = rdata->tailsz };

        cifs_dbg(FYI, "%s: mid=%llu state=%d result=%d bytes=%u\n",
                 __func__, mid->mid, mid->mid_state, rdata->result,
                 rdata->bytes);

        switch (mid->mid_state) {
        case MID_RESPONSE_RECEIVED:
                credits_received = le16_to_cpu(buf->CreditRequest);
                /* result already set, check signature */
                if (server->sign) {
                        int rc;

                        rc = smb2_verify_signature(&rqst, server);
                        if (rc)
                                cifs_dbg(VFS, "SMB signature verification returned error = %d\n",
                                         rc);
                }
                /* FIXME: should this be counted toward the initiating task? */
                task_io_account_read(rdata->got_bytes);
                cifs_stats_bytes_read(tcon, rdata->got_bytes);
                break;
        case MID_REQUEST_SUBMITTED:
        case MID_RETRY_NEEDED:
                rdata->result = -EAGAIN;
                if (server->sign && rdata->got_bytes)
                        /* reset bytes number since we can not check a sign */
                        rdata->got_bytes = 0;
                /* FIXME: should this be counted toward the initiating task? */
                task_io_account_read(rdata->got_bytes);
                cifs_stats_bytes_read(tcon, rdata->got_bytes);
                break;
        default:
                if (rdata->result != -ENODATA)
                        rdata->result = -EIO;
        }

        if (rdata->result)
                cifs_stats_fail_inc(tcon, SMB2_READ_HE);

        queue_work(cifsiod_wq, &rdata->work);
        mutex_lock(&server->srv_mutex);
        DeleteMidQEntry(mid);
        mutex_unlock(&server->srv_mutex);
        add_credits(server, credits_received, 0);
}

/* smb2_async_readv - send an async write, and set up mid to handle result */
int
smb2_async_readv(struct cifs_readdata *rdata)
{
        int rc, flags = 0;
        struct smb2_hdr *buf;
        struct cifs_io_parms io_parms;
        struct smb_rqst rqst = { .rq_iov = &rdata->iov,
                                 .rq_nvec = 1 };
        struct TCP_Server_Info *server;

        cifs_dbg(FYI, "%s: offset=%llu bytes=%u\n",
                 __func__, rdata->offset, rdata->bytes);

        io_parms.tcon = tlink_tcon(rdata->cfile->tlink);
        io_parms.offset = rdata->offset;
        io_parms.length = rdata->bytes;
        io_parms.persistent_fid = rdata->cfile->fid.persistent_fid;
        io_parms.volatile_fid = rdata->cfile->fid.volatile_fid;
        io_parms.pid = rdata->pid;

        server = io_parms.tcon->ses->server;

        rc = smb2_new_read_req(&rdata->iov, &io_parms, 0, 0);
        if (rc) {
                if (rc == -EAGAIN && rdata->credits) {
                        /* credits was reset by reconnect */
                        rdata->credits = 0;
                        /* reduce in_flight value since we won't send the req */
                        spin_lock(&server->req_lock);
                        server->in_flight--;
                        spin_unlock(&server->req_lock);
                }
                return rc;
        }

        buf = (struct smb2_hdr *)rdata->iov.iov_base;
        /* 4 for rfc1002 length field */
        rdata->iov.iov_len = get_rfc1002_length(rdata->iov.iov_base) + 4;

        if (rdata->credits) {
                buf->CreditCharge = cpu_to_le16(DIV_ROUND_UP(rdata->bytes,
                                                SMB2_MAX_BUFFER_SIZE));
                buf->CreditRequest = buf->CreditCharge;
                spin_lock(&server->req_lock);
                server->credits += rdata->credits -
                                                le16_to_cpu(buf->CreditCharge);
                spin_unlock(&server->req_lock);
                wake_up(&server->request_q);
                flags = CIFS_HAS_CREDITS;
        }

        kref_get(&rdata->refcount);
        rc = cifs_call_async(io_parms.tcon->ses->server, &rqst,
                             cifs_readv_receive, smb2_readv_callback,
                             rdata, flags);
        if (rc) {
                kref_put(&rdata->refcount, cifs_readdata_release);
                cifs_stats_fail_inc(io_parms.tcon, SMB2_READ_HE);
        }

        cifs_small_buf_release(buf);
        return rc;
}

int
SMB2_read(const unsigned int xid, struct cifs_io_parms *io_parms,
          unsigned int *nbytes, char **buf, int *buf_type)
{
        int resp_buftype, rc = -EACCES;
        struct smb2_read_rsp *rsp = NULL;
        struct kvec iov[1];

        *nbytes = 0;
        rc = smb2_new_read_req(iov, io_parms, 0, 0);
        if (rc)
                return rc;

        rc = SendReceive2(xid, io_parms->tcon->ses, iov, 1,
                          &resp_buftype, CIFS_LOG_ERROR);

        rsp = (struct smb2_read_rsp *)iov[0].iov_base;

        if (rsp->hdr.Status == STATUS_END_OF_FILE) {
                free_rsp_buf(resp_buftype, iov[0].iov_base);
                return 0;
        }

        if (rc) {
                cifs_stats_fail_inc(io_parms->tcon, SMB2_READ_HE);
                cifs_dbg(VFS, "Send error in read = %d\n", rc);
        } else {
                *nbytes = le32_to_cpu(rsp->DataLength);
                if ((*nbytes > CIFS_MAX_MSGSIZE) ||
                    (*nbytes > io_parms->length)) {
                        cifs_dbg(FYI, "bad length %d for count %d\n",
                                 *nbytes, io_parms->length);
                        rc = -EIO;
                        *nbytes = 0;
                }
        }

        if (*buf) {
                memcpy(*buf, (char *)&rsp->hdr.ProtocolId + rsp->DataOffset,
                       *nbytes);
                free_rsp_buf(resp_buftype, iov[0].iov_base);
        } else if (resp_buftype != CIFS_NO_BUFFER) {
                *buf = iov[0].iov_base;
                if (resp_buftype == CIFS_SMALL_BUFFER)
                        *buf_type = CIFS_SMALL_BUFFER;
                else if (resp_buftype == CIFS_LARGE_BUFFER)
                        *buf_type = CIFS_LARGE_BUFFER;
        }
        return rc;
}

/*
 * Check the mid_state and signature on received buffer (if any), and queue the
 * workqueue completion task.
 */
static void
smb2_writev_callback(struct mid_q_entry *mid)
{
        struct cifs_writedata *wdata = mid->callback_data;
        struct cifs_tcon *tcon = tlink_tcon(wdata->cfile->tlink);
        struct TCP_Server_Info *server = tcon->ses->server;
        unsigned int written;
        struct smb2_write_rsp *rsp = (struct smb2_write_rsp *)mid->resp_buf;
        unsigned int credits_received = 1;

        switch (mid->mid_state) {
        case MID_RESPONSE_RECEIVED:
                credits_received = le16_to_cpu(rsp->hdr.CreditRequest);
                wdata->result = smb2_check_receive(mid, tcon->ses->server, 0);
                if (wdata->result != 0)
                        break;

                written = le32_to_cpu(rsp->DataLength);
                /*
                 * Mask off high 16 bits when bytes written as returned
                 * by the server is greater than bytes requested by the
                 * client. OS/2 servers are known to set incorrect
                 * CountHigh values.
                 */
                if (written > wdata->bytes)
                        written &= 0xFFFF;

                if (written < wdata->bytes)
                        wdata->result = -ENOSPC;
                else
                        wdata->bytes = written;
                break;
        case MID_REQUEST_SUBMITTED:
        case MID_RETRY_NEEDED:
                wdata->result = -EAGAIN;
                break;
        default:
                wdata->result = -EIO;
                break;
        }

        if (wdata->result)
                cifs_stats_fail_inc(tcon, SMB2_WRITE_HE);

        queue_work(cifsiod_wq, &wdata->work);
        mutex_lock(&server->srv_mutex);
        DeleteMidQEntry(mid);
        mutex_unlock(&server->srv_mutex);
        add_credits(tcon->ses->server, credits_received, 0);
}

/* smb2_async_writev - send an async write, and set up mid to handle result */
int
smb2_async_writev(struct cifs_writedata *wdata,
                  void (*release)(struct kref *kref))
{
        int rc = -EACCES, flags = 0;
        struct smb2_write_req *req = NULL;
        struct cifs_tcon *tcon = tlink_tcon(wdata->cfile->tlink);
        struct TCP_Server_Info *server = tcon->ses->server;
        struct kvec iov;
        struct smb_rqst rqst;

        rc = small_smb2_init(SMB2_WRITE, tcon, (void **) &req);
        if (rc) {
                if (rc == -EAGAIN && wdata->credits) {
                        /* credits was reset by reconnect */
                        wdata->credits = 0;
                        /* reduce in_flight value since we won't send the req */
                        spin_lock(&server->req_lock);
                        server->in_flight--;
                        spin_unlock(&server->req_lock);
                }
                goto async_writev_out;
        }

        req->hdr.ProcessId = cpu_to_le32(wdata->cfile->pid);

        req->PersistentFileId = wdata->cfile->fid.persistent_fid;
        req->VolatileFileId = wdata->cfile->fid.volatile_fid;
        req->WriteChannelInfoOffset = 0;
        req->WriteChannelInfoLength = 0;
        req->Channel = 0;
        req->Offset = cpu_to_le64(wdata->offset);
        /* 4 for rfc1002 length field */
        req->DataOffset = cpu_to_le16(
                                offsetof(struct smb2_write_req, Buffer) - 4);
        req->RemainingBytes = 0;

        /* 4 for rfc1002 length field and 1 for Buffer */
        iov.iov_len = get_rfc1002_length(req) + 4 - 1;
        iov.iov_base = req;

        rqst.rq_iov = &iov;
        rqst.rq_nvec = 1;
        rqst.rq_pages = wdata->pages;
        rqst.rq_npages = wdata->nr_pages;
        rqst.rq_pagesz = wdata->pagesz;
        rqst.rq_tailsz = wdata->tailsz;

        cifs_dbg(FYI, "async write at %llu %u bytes\n",
                 wdata->offset, wdata->bytes);

        req->Length = cpu_to_le32(wdata->bytes);

        inc_rfc1001_len(&req->hdr, wdata->bytes - 1 /* Buffer */);

        if (wdata->credits) {
                req->hdr.CreditCharge = cpu_to_le16(DIV_ROUND_UP(wdata->bytes,
                                                    SMB2_MAX_BUFFER_SIZE));
                req->hdr.CreditRequest = req->hdr.CreditCharge;
                spin_lock(&server->req_lock);
                server->credits += wdata->credits -
                                        le16_to_cpu(req->hdr.CreditCharge);
                spin_unlock(&server->req_lock);
                wake_up(&server->request_q);
                flags = CIFS_HAS_CREDITS;
        }

        kref_get(&wdata->refcount);
        rc = cifs_call_async(server, &rqst, NULL, smb2_writev_callback, wdata,
                             flags);

        if (rc) {
                kref_put(&wdata->refcount, release);
                cifs_stats_fail_inc(tcon, SMB2_WRITE_HE);
        }

async_writev_out:
        cifs_small_buf_release(req);
        return rc;
}

/*
 * SMB2_write function gets iov pointer to kvec array with n_vec as a length.
 * The length field from io_parms must be at least 1 and indicates a number of
 * elements with data to write that begins with position 1 in iov array. All
 * data length is specified by count.
 */
int
SMB2_write(const unsigned int xid, struct cifs_io_parms *io_parms,
           unsigned int *nbytes, struct kvec *iov, int n_vec)
{
        int rc = 0;
        struct smb2_write_req *req = NULL;
        struct smb2_write_rsp *rsp = NULL;
        int resp_buftype;
        *nbytes = 0;

        if (n_vec < 1)
                return rc;

        rc = small_smb2_init(SMB2_WRITE, io_parms->tcon, (void **) &req);
        if (rc)
                return rc;

        if (io_parms->tcon->ses->server == NULL)
                return -ECONNABORTED;

        req->hdr.ProcessId = cpu_to_le32(io_parms->pid);

        req->PersistentFileId = io_parms->persistent_fid;
        req->VolatileFileId = io_parms->volatile_fid;
        req->WriteChannelInfoOffset = 0;
        req->WriteChannelInfoLength = 0;
        req->Channel = 0;
        req->Length = cpu_to_le32(io_parms->length);
        req->Offset = cpu_to_le64(io_parms->offset);
        /* 4 for rfc1002 length field */
        req->DataOffset = cpu_to_le16(
                                offsetof(struct smb2_write_req, Buffer) - 4);
        req->RemainingBytes = 0;

        iov[0].iov_base = (char *)req;
        /* 4 for rfc1002 length field and 1 for Buffer */
        iov[0].iov_len = get_rfc1002_length(req) + 4 - 1;

        /* length of entire message including data to be written */
        inc_rfc1001_len(req, io_parms->length - 1 /* Buffer */);

        rc = SendReceive2(xid, io_parms->tcon->ses, iov, n_vec + 1,
                          &resp_buftype, 0);
        rsp = (struct smb2_write_rsp *)iov[0].iov_base;

        if (rc) {
                cifs_stats_fail_inc(io_parms->tcon, SMB2_WRITE_HE);
                cifs_dbg(VFS, "Send error in write = %d\n", rc);
        } else
                *nbytes = le32_to_cpu(rsp->DataLength);

        free_rsp_buf(resp_buftype, rsp);
        return rc;
}

static unsigned int
num_entries(char *bufstart, char *end_of_buf, char **lastentry, size_t size)
{
        int len;
        unsigned int entrycount = 0;
        unsigned int next_offset = 0;
        FILE_DIRECTORY_INFO *entryptr;

        if (bufstart == NULL)
                return 0;

        entryptr = (FILE_DIRECTORY_INFO *)bufstart;

        while (1) {
                entryptr = (FILE_DIRECTORY_INFO *)
                                        ((char *)entryptr + next_offset);

                if ((char *)entryptr + size > end_of_buf) {
                        cifs_dbg(VFS, "malformed search entry would overflow\n");
                        break;
                }

                len = le32_to_cpu(entryptr->FileNameLength);
                if ((char *)entryptr + len + size > end_of_buf) {
                        cifs_dbg(VFS, "directory entry name would overflow frame end of buf %p\n",
                                 end_of_buf);
                        break;
                }

                *lastentry = (char *)entryptr;
                entrycount++;

                next_offset = le32_to_cpu(entryptr->NextEntryOffset);
                if (!next_offset)
                        break;
        }

        return entrycount;
}

/*
 * Readdir/FindFirst
 */
int
SMB2_query_directory(const unsigned int xid, struct cifs_tcon *tcon,
                     u64 persistent_fid, u64 volatile_fid, int index,
                     struct cifs_search_info *srch_inf)
{
        struct smb2_query_directory_req *req;
        struct smb2_query_directory_rsp *rsp = NULL;
        struct kvec iov[2];
        int rc = 0;
        int len;
        int resp_buftype = CIFS_NO_BUFFER;
        unsigned char *bufptr;
        struct TCP_Server_Info *server;
        struct cifs_ses *ses = tcon->ses;
        __le16 asteriks = cpu_to_le16('*');
        char *end_of_smb;
        unsigned int output_size = CIFSMaxBufSize;
        size_t info_buf_size;

        if (ses && (ses->server))
                server = ses->server;
        else
                return -EIO;

        rc = small_smb2_init(SMB2_QUERY_DIRECTORY, tcon, (void **) &req);
        if (rc)
                return rc;

        switch (srch_inf->info_level) {
        case SMB_FIND_FILE_DIRECTORY_INFO:
                req->FileInformationClass = FILE_DIRECTORY_INFORMATION;
                info_buf_size = sizeof(FILE_DIRECTORY_INFO) - 1;
                break;
        case SMB_FIND_FILE_ID_FULL_DIR_INFO:
                req->FileInformationClass = FILEID_FULL_DIRECTORY_INFORMATION;
                info_buf_size = sizeof(SEARCH_ID_FULL_DIR_INFO) - 1;
                break;
        default:
                cifs_dbg(VFS, "info level %u isn't supported\n",
                         srch_inf->info_level);
                rc = -EINVAL;
                goto qdir_exit;
        }

        req->FileIndex = cpu_to_le32(index);
        req->PersistentFileId = persistent_fid;
        req->VolatileFileId = volatile_fid;

        len = 0x2;
        bufptr = req->Buffer;
        memcpy(bufptr, &asteriks, len);

        req->FileNameOffset =
                cpu_to_le16(sizeof(struct smb2_query_directory_req) - 1 - 4);
        req->FileNameLength = cpu_to_le16(len);
        /*
         * BB could be 30 bytes or so longer if we used SMB2 specific
         * buffer lengths, but this is safe and close enough.
         */
        output_size = min_t(unsigned int, output_size, server->maxBuf);
        output_size = min_t(unsigned int, output_size, 2 << 15);
        req->OutputBufferLength = cpu_to_le32(output_size);

        iov[0].iov_base = (char *)req;
        /* 4 for RFC1001 length and 1 for Buffer */
        iov[0].iov_len = get_rfc1002_length(req) + 4 - 1;

        iov[1].iov_base = (char *)(req->Buffer);
        iov[1].iov_len = len;

        inc_rfc1001_len(req, len - 1 /* Buffer */);

        rc = SendReceive2(xid, ses, iov, 2, &resp_buftype, 0);
        rsp = (struct smb2_query_directory_rsp *)iov[0].iov_base;

        if (rc) {
                if (rc == -ENODATA && rsp->hdr.Status == STATUS_NO_MORE_FILES) {
                        srch_inf->endOfSearch = true;
                        rc = 0;
                }
                cifs_stats_fail_inc(tcon, SMB2_QUERY_DIRECTORY_HE);
                goto qdir_exit;
        }

        rc = validate_buf(le16_to_cpu(rsp->OutputBufferOffset),
                          le32_to_cpu(rsp->OutputBufferLength), &rsp->hdr,
                          info_buf_size);
        if (rc)
                goto qdir_exit;

        srch_inf->unicode = true;

        if (srch_inf->ntwrk_buf_start) {
                if (srch_inf->smallBuf)
                        cifs_small_buf_release(srch_inf->ntwrk_buf_start);
                else
                        cifs_buf_release(srch_inf->ntwrk_buf_start);
        }
        srch_inf->ntwrk_buf_start = (char *)rsp;
        srch_inf->srch_entries_start = srch_inf->last_entry = 4 /* rfclen */ +
                (char *)&rsp->hdr + le16_to_cpu(rsp->OutputBufferOffset);
        /* 4 for rfc1002 length field */
        end_of_smb = get_rfc1002_length(rsp) + 4 + (char *)&rsp->hdr;
        srch_inf->entries_in_buffer =
                        num_entries(srch_inf->srch_entries_start, end_of_smb,
                                    &srch_inf->last_entry, info_buf_size);
        srch_inf->index_of_last_entry += srch_inf->entries_in_buffer;
        cifs_dbg(FYI, "num entries %d last_index %lld srch start %p srch end %p\n",
                 srch_inf->entries_in_buffer, srch_inf->index_of_last_entry,
                 srch_inf->srch_entries_start, srch_inf->last_entry);
        if (resp_buftype == CIFS_LARGE_BUFFER)
                srch_inf->smallBuf = false;
        else if (resp_buftype == CIFS_SMALL_BUFFER)
                srch_inf->smallBuf = true;
        else
                cifs_dbg(VFS, "illegal search buffer type\n");

        return rc;

qdir_exit:
        free_rsp_buf(resp_buftype, rsp);
        return rc;
}

static int
send_set_info(const unsigned int xid, struct cifs_tcon *tcon,
               u64 persistent_fid, u64 volatile_fid, u32 pid, int info_class,
               unsigned int num, void **data, unsigned int *size)
{
        struct smb2_set_info_req *req;
        struct smb2_set_info_rsp *rsp = NULL;
        struct kvec *iov;
        int rc = 0;
        int resp_buftype;
        unsigned int i;
        struct TCP_Server_Info *server;
        struct cifs_ses *ses = tcon->ses;

        if (ses && (ses->server))
                server = ses->server;
        else
                return -EIO;

        if (!num)
                return -EINVAL;

        iov = kmalloc(sizeof(struct kvec) * num, GFP_KERNEL);
        if (!iov)
                return -ENOMEM;

        rc = small_smb2_init(SMB2_SET_INFO, tcon, (void **) &req);
        if (rc) {
                kfree(iov);
                return rc;
        }

        req->hdr.ProcessId = cpu_to_le32(pid);

        req->InfoType = SMB2_O_INFO_FILE;
        req->FileInfoClass = info_class;
        req->PersistentFileId = persistent_fid;
        req->VolatileFileId = volatile_fid;

        /* 4 for RFC1001 length and 1 for Buffer */
        req->BufferOffset =
                        cpu_to_le16(sizeof(struct smb2_set_info_req) - 1 - 4);
        req->BufferLength = cpu_to_le32(*size);

        inc_rfc1001_len(req, *size - 1 /* Buffer */);

        memcpy(req->Buffer, *data, *size);

        iov[0].iov_base = (char *)req;
        /* 4 for RFC1001 length */
        iov[0].iov_len = get_rfc1002_length(req) + 4;

        for (i = 1; i < num; i++) {
                inc_rfc1001_len(req, size[i]);
                le32_add_cpu(&req->BufferLength, size[i]);
                iov[i].iov_base = (char *)data[i];
                iov[i].iov_len = size[i];
        }

        rc = SendReceive2(xid, ses, iov, num, &resp_buftype, 0);
        rsp = (struct smb2_set_info_rsp *)iov[0].iov_base;

        if (rc != 0)
                cifs_stats_fail_inc(tcon, SMB2_SET_INFO_HE);

        free_rsp_buf(resp_buftype, rsp);
        kfree(iov);
        return rc;
}

int
SMB2_rename(const unsigned int xid, struct cifs_tcon *tcon,
            u64 persistent_fid, u64 volatile_fid, __le16 *target_file)
{
        struct smb2_file_rename_info info;
        void **data;
        unsigned int size[2];
        int rc;
        int len = (2 * UniStrnlen((wchar_t *)target_file, PATH_MAX));

        data = kmalloc(sizeof(void *) * 2, GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        info.ReplaceIfExists = 1; /* 1 = replace existing target with new */
                              /* 0 = fail if target already exists */
        info.RootDirectory = 0;  /* MBZ for network ops (why does spec say?) */
        info.FileNameLength = cpu_to_le32(len);

        data[0] = &info;
        size[0] = sizeof(struct smb2_file_rename_info);

        data[1] = target_file;
        size[1] = len + 2 /* null */;

        rc = send_set_info(xid, tcon, persistent_fid, volatile_fid,
                           current->tgid, FILE_RENAME_INFORMATION, 2, data,
                           size);
        kfree(data);
        return rc;
}

int
SMB2_rmdir(const unsigned int xid, struct cifs_tcon *tcon,
                  u64 persistent_fid, u64 volatile_fid)
{
        __u8 delete_pending = 1;
        void *data;
        unsigned int size;

        data = &delete_pending;
        size = 1; /* sizeof __u8 */

        return send_set_info(xid, tcon, persistent_fid, volatile_fid,
                        current->tgid, FILE_DISPOSITION_INFORMATION, 1, &data,
                        &size);
}

int
SMB2_set_hardlink(const unsigned int xid, struct cifs_tcon *tcon,
                  u64 persistent_fid, u64 volatile_fid, __le16 *target_file)
{
        struct smb2_file_link_info info;
        void **data;
        unsigned int size[2];
        int rc;
        int len = (2 * UniStrnlen((wchar_t *)target_file, PATH_MAX));

        data = kmalloc(sizeof(void *) * 2, GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        info.ReplaceIfExists = 0; /* 1 = replace existing link with new */
                              /* 0 = fail if link already exists */
        info.RootDirectory = 0;  /* MBZ for network ops (why does spec say?) */
        info.FileNameLength = cpu_to_le32(len);

        data[0] = &info;
        size[0] = sizeof(struct smb2_file_link_info);

        data[1] = target_file;
        size[1] = len + 2 /* null */;

        rc = send_set_info(xid, tcon, persistent_fid, volatile_fid,
                           current->tgid, FILE_LINK_INFORMATION, 2, data, size);
        kfree(data);
        return rc;
}

int
SMB2_set_eof(const unsigned int xid, struct cifs_tcon *tcon, u64 persistent_fid,
             u64 volatile_fid, u32 pid, __le64 *eof, bool is_falloc)
{
        struct smb2_file_eof_info info;
        void *data;
        unsigned int size;

        info.EndOfFile = *eof;

        data = &info;
        size = sizeof(struct smb2_file_eof_info);

        if (is_falloc)
                return send_set_info(xid, tcon, persistent_fid, volatile_fid,
                        pid, FILE_ALLOCATION_INFORMATION, 1, &data, &size);
        else
                return send_set_info(xid, tcon, persistent_fid, volatile_fid,
                        pid, FILE_END_OF_FILE_INFORMATION, 1, &data, &size);
}

int
SMB2_set_info(const unsigned int xid, struct cifs_tcon *tcon,
              u64 persistent_fid, u64 volatile_fid, FILE_BASIC_INFO *buf)
{
        unsigned int size;
        size = sizeof(FILE_BASIC_INFO);
        return send_set_info(xid, tcon, persistent_fid, volatile_fid,
                             current->tgid, FILE_BASIC_INFORMATION, 1,
                             (void **)&buf, &size);
}

int
SMB2_oplock_break(const unsigned int xid, struct cifs_tcon *tcon,
                  const u64 persistent_fid, const u64 volatile_fid,
                  __u8 oplock_level)
{
        int rc;
        struct smb2_oplock_break *req = NULL;

        cifs_dbg(FYI, "SMB2_oplock_break\n");
        rc = small_smb2_init(SMB2_OPLOCK_BREAK, tcon, (void **) &req);

        if (rc)
                return rc;

        req->VolatileFid = volatile_fid;
        req->PersistentFid = persistent_fid;
        req->OplockLevel = oplock_level;
        req->hdr.CreditRequest = cpu_to_le16(1);

        rc = SendReceiveNoRsp(xid, tcon->ses, (char *) req, CIFS_OBREAK_OP);
        /* SMB2 buffer freed by function above */

        if (rc) {
                cifs_stats_fail_inc(tcon, SMB2_OPLOCK_BREAK_HE);
                cifs_dbg(FYI, "Send error in Oplock Break = %d\n", rc);
        }

        return rc;
}

static void
copy_fs_info_to_kstatfs(struct smb2_fs_full_size_info *pfs_inf,
                        struct kstatfs *kst)
{
        kst->f_bsize = le32_to_cpu(pfs_inf->BytesPerSector) *
                          le32_to_cpu(pfs_inf->SectorsPerAllocationUnit);
        kst->f_blocks = le64_to_cpu(pfs_inf->TotalAllocationUnits);
        kst->f_bfree  = le64_to_cpu(pfs_inf->ActualAvailableAllocationUnits);
        kst->f_bavail = le64_to_cpu(pfs_inf->CallerAvailableAllocationUnits);
        return;
}

static int
build_qfs_info_req(struct kvec *iov, struct cifs_tcon *tcon, int level,
                   int outbuf_len, u64 persistent_fid, u64 volatile_fid)
{
        int rc;
        struct smb2_query_info_req *req;

        cifs_dbg(FYI, "Query FSInfo level %d\n", level);

        if ((tcon->ses == NULL) || (tcon->ses->server == NULL))
                return -EIO;

        rc = small_smb2_init(SMB2_QUERY_INFO, tcon, (void **) &req);
        if (rc)
                return rc;

        req->InfoType = SMB2_O_INFO_FILESYSTEM;
        req->FileInfoClass = level;
        req->PersistentFileId = persistent_fid;
        req->VolatileFileId = volatile_fid;
        /* 4 for rfc1002 length field and 1 for pad */
        req->InputBufferOffset =
                        cpu_to_le16(sizeof(struct smb2_query_info_req) - 1 - 4);
        req->OutputBufferLength = cpu_to_le32(
                outbuf_len + sizeof(struct smb2_query_info_rsp) - 1 - 4);

        iov->iov_base = (char *)req;
        /* 4 for rfc1002 length field */
        iov->iov_len = get_rfc1002_length(req) + 4;
        return 0;
}

int
SMB2_QFS_info(const unsigned int xid, struct cifs_tcon *tcon,
              u64 persistent_fid, u64 volatile_fid, struct kstatfs *fsdata)
{
        struct smb2_query_info_rsp *rsp = NULL;
        struct kvec iov;
        int rc = 0;
        int resp_buftype;
        struct cifs_ses *ses = tcon->ses;
        struct smb2_fs_full_size_info *info = NULL;

        rc = build_qfs_info_req(&iov, tcon, FS_FULL_SIZE_INFORMATION,
                                sizeof(struct smb2_fs_full_size_info),
                                persistent_fid, volatile_fid);
        if (rc)
                return rc;

        rc = SendReceive2(xid, ses, &iov, 1, &resp_buftype, 0);
        if (rc) {
                cifs_stats_fail_inc(tcon, SMB2_QUERY_INFO_HE);
                goto qfsinf_exit;
        }
        rsp = (struct smb2_query_info_rsp *)iov.iov_base;

        info = (struct smb2_fs_full_size_info *)(4 /* RFC1001 len */ +
                le16_to_cpu(rsp->OutputBufferOffset) + (char *)&rsp->hdr);
        rc = validate_buf(le16_to_cpu(rsp->OutputBufferOffset),
                          le32_to_cpu(rsp->OutputBufferLength), &rsp->hdr,
                          sizeof(struct smb2_fs_full_size_info));
        if (!rc)
                copy_fs_info_to_kstatfs(info, fsdata);

qfsinf_exit:
        free_rsp_buf(resp_buftype, iov.iov_base);
        return rc;
}

int
SMB2_QFS_attr(const unsigned int xid, struct cifs_tcon *tcon,
              u64 persistent_fid, u64 volatile_fid, int level)
{
        struct smb2_query_info_rsp *rsp = NULL;
        struct kvec iov;
        int rc = 0;
        int resp_buftype, max_len, min_len;
        struct cifs_ses *ses = tcon->ses;