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[Samba.git] / source / smbd / aio.c

/*
   Unix SMB/Netbios implementation.
   Version 3.0
   async_io read handling using POSIX async io.
   Copyright (C) Jeremy Allison 2005.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"

#if defined(WITH_AIO)

/* The signal we'll use to signify aio done. */
#ifndef RT_SIGNAL_AIO
#ifndef SIGRTMIN
#define SIGRTMIN        NSIG
#endif
#define RT_SIGNAL_AIO   (SIGRTMIN+3)
#endif

#ifndef HAVE_STRUCT_SIGEVENT_SIGEV_VALUE_SIVAL_PTR
#ifdef HAVE_STRUCT_SIGEVENT_SIGEV_VALUE_SIGVAL_PTR
#define sival_int       sigval_int
#define sival_ptr       sigval_ptr
#endif
#endif

/****************************************************************************
 The buffer we keep around whilst an aio request is in process.
*****************************************************************************/

struct aio_extra {
        struct aio_extra *next, *prev;
        SMB_STRUCT_AIOCB acb;
        files_struct *fsp;
        bool read_req;
        uint16 mid;
        char *inbuf;
        char *outbuf;
};

static struct aio_extra *aio_list_head;

/****************************************************************************
 Create the extended aio struct we must keep around for the lifetime
 of the aio_read call.
*****************************************************************************/

static struct aio_extra *create_aio_ex_read(files_struct *fsp, size_t buflen,
                                            uint16 mid)
{
        struct aio_extra *aio_ex = SMB_MALLOC_P(struct aio_extra);

        if (!aio_ex) {
                return NULL;
        }
        ZERO_STRUCTP(aio_ex);
        /* The output buffer stored in the aio_ex is the start of
           the smb return buffer. The buffer used in the acb
           is the start of the reply data portion of that buffer. */
        aio_ex->outbuf = SMB_MALLOC_ARRAY(char, buflen);
        if (!aio_ex->outbuf) {
                SAFE_FREE(aio_ex);
                return NULL;
        }
        DLIST_ADD(aio_list_head, aio_ex);
        aio_ex->fsp = fsp;
        aio_ex->read_req = True;
        aio_ex->mid = mid;
        return aio_ex;
}

/****************************************************************************
 Create the extended aio struct we must keep around for the lifetime
 of the aio_write call.
*****************************************************************************/

static struct aio_extra *create_aio_ex_write(files_struct *fsp,
                                             size_t inbuflen,
                                             size_t outbuflen,
                                             uint16 mid)
{
        struct aio_extra *aio_ex = SMB_MALLOC_P(struct aio_extra);

        if (!aio_ex) {
                return NULL;
        }
        ZERO_STRUCTP(aio_ex);

        /* We need space for an output reply of outbuflen bytes. */
        aio_ex->outbuf = SMB_MALLOC_ARRAY(char, outbuflen);
        if (!aio_ex->outbuf) {
                SAFE_FREE(aio_ex);
                return NULL;
        }

        if (!(aio_ex->inbuf = SMB_MALLOC_ARRAY(char, inbuflen))) {
                SAFE_FREE(aio_ex->outbuf);
                SAFE_FREE(aio_ex);
                return NULL;
        }

        DLIST_ADD(aio_list_head, aio_ex);
        aio_ex->fsp = fsp;
        aio_ex->read_req = False;
        aio_ex->mid = mid;
        return aio_ex;
}

/****************************************************************************
 Delete the extended aio struct.
*****************************************************************************/

static void delete_aio_ex(struct aio_extra *aio_ex)
{
        DLIST_REMOVE(aio_list_head, aio_ex);
        SAFE_FREE(aio_ex->inbuf);
        SAFE_FREE(aio_ex->outbuf);
        SAFE_FREE(aio_ex);
}

/****************************************************************************
 Given the aiocb struct find the extended aio struct containing it.
*****************************************************************************/

static struct aio_extra *find_aio_ex(uint16 mid)
{
        struct aio_extra *p;

        for( p = aio_list_head; p; p = p->next) {
                if (mid == p->mid) {
                        return p;
                }
        }
        return NULL;
}

/****************************************************************************
 We can have these many aio buffers in flight.
*****************************************************************************/

static int aio_pending_size;
static sig_atomic_t signals_received;
static int outstanding_aio_calls;
static uint16 *aio_pending_array;

/****************************************************************************
 Signal handler when an aio request completes.
*****************************************************************************/

void aio_request_done(uint16_t mid)
{
        if (signals_received < aio_pending_size) {
                aio_pending_array[signals_received] = mid;
                signals_received++;
        }
        /* Else signal is lost. */
}

static void signal_handler(int sig, siginfo_t *info, void *unused)
{
        aio_request_done(info->si_value.sival_int);
        sys_select_signal(RT_SIGNAL_AIO);
}

/****************************************************************************
 Is there a signal waiting ?
*****************************************************************************/

bool aio_finished(void)
{
        return (signals_received != 0);
}

/****************************************************************************
 Initialize the signal handler for aio read/write.
*****************************************************************************/

void initialize_async_io_handler(void)
{
        struct sigaction act;

        aio_pending_size = lp_maxmux();
        aio_pending_array = SMB_MALLOC_ARRAY(uint16, aio_pending_size);
        SMB_ASSERT(aio_pending_array != NULL);

        ZERO_STRUCT(act);
        act.sa_sigaction = signal_handler;
        act.sa_flags = SA_SIGINFO;
        sigemptyset( &act.sa_mask );
        if (sigaction(RT_SIGNAL_AIO, &act, NULL) != 0) {
                DEBUG(0,("Failed to setup RT_SIGNAL_AIO handler\n"));
        }

        /* the signal can start off blocked due to a bug in bash */
        BlockSignals(False, RT_SIGNAL_AIO);
}

/****************************************************************************
 Set up an aio request from a SMBreadX call.
*****************************************************************************/

bool schedule_aio_read_and_X(connection_struct *conn,
                             struct smb_request *req,
                             files_struct *fsp, SMB_OFF_T startpos,
                             size_t smb_maxcnt)
{
        struct aio_extra *aio_ex;
        SMB_STRUCT_AIOCB *a;
        size_t bufsize;
        size_t min_aio_read_size = lp_aio_read_size(SNUM(conn));

        if (fsp->base_fsp != NULL) {
                /* No AIO on streams yet */
                DEBUG(10, ("AIO on streams not yet supported\n"));
                return false;
        }

        if ((!min_aio_read_size || (smb_maxcnt < min_aio_read_size))
            && !SMB_VFS_AIO_FORCE(fsp)) {
                /* Too small a read for aio request. */
                DEBUG(10,("schedule_aio_read_and_X: read size (%u) too small "
                          "for minimum aio_read of %u\n",
                          (unsigned int)smb_maxcnt,
                          (unsigned int)min_aio_read_size ));
                return False;
        }

        /* Only do this on non-chained and non-chaining reads not using the
         * write cache. */
        if (chain_size !=0 || (CVAL(req->inbuf,smb_vwv0) != 0xFF)
            || (lp_write_cache_size(SNUM(conn)) != 0) ) {
                return False;
        }

        if (outstanding_aio_calls >= aio_pending_size) {
                DEBUG(10,("schedule_aio_read_and_X: Already have %d aio "
                          "activities outstanding.\n",
                          outstanding_aio_calls ));
                return False;
        }

        /* The following is safe from integer wrap as we've already checked
           smb_maxcnt is 128k or less. Wct is 12 for read replies */

        bufsize = smb_size + 12 * 2 + smb_maxcnt;

        if ((aio_ex = create_aio_ex_read(fsp, bufsize, req->mid)) == NULL) {
                DEBUG(10,("schedule_aio_read_and_X: malloc fail.\n"));
                return False;
        }

        construct_reply_common((char *)req->inbuf, aio_ex->outbuf);
        srv_set_message(aio_ex->outbuf, 12, 0, True);
        SCVAL(aio_ex->outbuf,smb_vwv0,0xFF); /* Never a chained reply. */

        a = &aio_ex->acb;

        /* Now set up the aio record for the read call. */
        
        a->aio_fildes = fsp->fh->fd;
        a->aio_buf = smb_buf(aio_ex->outbuf);
        a->aio_nbytes = smb_maxcnt;
        a->aio_offset = startpos;
        a->aio_sigevent.sigev_notify = SIGEV_SIGNAL;
        a->aio_sigevent.sigev_signo  = RT_SIGNAL_AIO;
        a->aio_sigevent.sigev_value.sival_int = aio_ex->mid;

        become_root();
        if (SMB_VFS_AIO_READ(fsp,a) == -1) {
                DEBUG(0,("schedule_aio_read_and_X: aio_read failed. "
                         "Error %s\n", strerror(errno) ));
                delete_aio_ex(aio_ex);
                unbecome_root();
                return False;
        }
        unbecome_root();

        DEBUG(10,("schedule_aio_read_and_X: scheduled aio_read for file %s, "
                  "offset %.0f, len = %u (mid = %u)\n",
                  fsp->fsp_name, (double)startpos, (unsigned int)smb_maxcnt,
                  (unsigned int)aio_ex->mid ));

        srv_defer_sign_response(aio_ex->mid);
        outstanding_aio_calls++;
        return True;
}

/****************************************************************************
 Set up an aio request from a SMBwriteX call.
*****************************************************************************/

bool schedule_aio_write_and_X(connection_struct *conn,
                              struct smb_request *req,
                              files_struct *fsp, char *data,
                              SMB_OFF_T startpos,
                              size_t numtowrite)
{
        struct aio_extra *aio_ex;
        SMB_STRUCT_AIOCB *a;
        size_t inbufsize, outbufsize;
        bool write_through = BITSETW(req->inbuf+smb_vwv7,0);
        size_t min_aio_write_size = lp_aio_write_size(SNUM(conn));

        if (fsp->base_fsp != NULL) {
                /* No AIO on streams yet */
                DEBUG(10, ("AIO on streams not yet supported\n"));
                return false;
        }

        if ((!min_aio_write_size || (numtowrite < min_aio_write_size))
            && !SMB_VFS_AIO_FORCE(fsp)) {
                /* Too small a write for aio request. */
                DEBUG(10,("schedule_aio_write_and_X: write size (%u) too "
                          "small for minimum aio_write of %u\n",
                          (unsigned int)numtowrite,
                          (unsigned int)min_aio_write_size ));
                return False;
        }

        /* Only do this on non-chained and non-chaining reads not using the
         * write cache. */
        if (chain_size !=0 || (CVAL(req->inbuf,smb_vwv0) != 0xFF)
            || (lp_write_cache_size(SNUM(conn)) != 0) ) {
                return False;
        }

        if (outstanding_aio_calls >= aio_pending_size) {
                DEBUG(3,("schedule_aio_write_and_X: Already have %d aio "
                         "activities outstanding.\n",
                          outstanding_aio_calls ));
                DEBUG(10,("schedule_aio_write_and_X: failed to schedule "
                          "aio_write for file %s, offset %.0f, len = %u "
                          "(mid = %u)\n",
                          fsp->fsp_name, (double)startpos,
                          (unsigned int)numtowrite,
                          (unsigned int)req->mid ));
                return False;
        }

        inbufsize =  smb_len(req->inbuf) + 4;
        reply_outbuf(req, 6, 0);
        outbufsize = smb_len(req->outbuf) + 4;
        if (!(aio_ex = create_aio_ex_write(fsp, inbufsize, outbufsize,
                                           req->mid))) {
                DEBUG(0,("schedule_aio_write_and_X: malloc fail.\n"));
                return False;
        }

        /* Copy the SMB header already setup in outbuf. */
        memcpy(aio_ex->inbuf, req->inbuf, inbufsize);

        /* Copy the SMB header already setup in outbuf. */
        memcpy(aio_ex->outbuf, req->outbuf, outbufsize);
        TALLOC_FREE(req->outbuf);
        SCVAL(aio_ex->outbuf,smb_vwv0,0xFF); /* Never a chained reply. */

        a = &aio_ex->acb;

        /* Now set up the aio record for the write call. */
        
        a->aio_fildes = fsp->fh->fd;
        a->aio_buf = aio_ex->inbuf + (PTR_DIFF(data, req->inbuf));
        a->aio_nbytes = numtowrite;
        a->aio_offset = startpos;
        a->aio_sigevent.sigev_notify = SIGEV_SIGNAL;
        a->aio_sigevent.sigev_signo  = RT_SIGNAL_AIO;
        a->aio_sigevent.sigev_value.sival_int = aio_ex->mid;

        become_root();
        if (SMB_VFS_AIO_WRITE(fsp,a) == -1) {
                DEBUG(3,("schedule_aio_wrote_and_X: aio_write failed. "
                         "Error %s\n", strerror(errno) ));
                delete_aio_ex(aio_ex);
                unbecome_root();
                return False;
        }
        unbecome_root();
        
        release_level_2_oplocks_on_change(fsp);

        if (!write_through && !lp_syncalways(SNUM(fsp->conn))
            && fsp->aio_write_behind) {
                /* Lie to the client and immediately claim we finished the
                 * write. */
                SSVAL(aio_ex->outbuf,smb_vwv2,numtowrite);
                SSVAL(aio_ex->outbuf,smb_vwv4,(numtowrite>>16)&1);
                show_msg(aio_ex->outbuf);
                if (!srv_send_smb(smbd_server_fd(),aio_ex->outbuf,
                                IS_CONN_ENCRYPTED(fsp->conn))) {
                        exit_server_cleanly("handle_aio_write: srv_send_smb "
                                            "failed.");
                }
                DEBUG(10,("schedule_aio_write_and_X: scheduled aio_write "
                          "behind for file %s\n", fsp->fsp_name ));
        } else {
                srv_defer_sign_response(aio_ex->mid);
        }
        outstanding_aio_calls++;

        DEBUG(10,("schedule_aio_write_and_X: scheduled aio_write for file "
                  "%s, offset %.0f, len = %u (mid = %u) "
                  "outstanding_aio_calls = %d\n",
                  fsp->fsp_name, (double)startpos, (unsigned int)numtowrite,
                  (unsigned int)aio_ex->mid, outstanding_aio_calls ));

        return True;
}


/****************************************************************************
 Complete the read and return the data or error back to the client.
 Returns errno or zero if all ok.
*****************************************************************************/

static int handle_aio_read_complete(struct aio_extra *aio_ex)
{
        int ret = 0;
        int outsize;
        char *outbuf = aio_ex->outbuf;
        char *data = smb_buf(outbuf);
        ssize_t nread = SMB_VFS_AIO_RETURN(aio_ex->fsp,&aio_ex->acb);

        if (nread < 0) {
                /* We're relying here on the fact that if the fd is
                   closed then the aio will complete and aio_return
                   will return an error. Hopefully this is
                   true.... JRA. */

                /* If errno is ECANCELED then don't return anything to the
                 * client. */
                if (errno == ECANCELED) {
                        srv_cancel_sign_response(aio_ex->mid);
                        return 0;
                }

                DEBUG( 3,( "handle_aio_read_complete: file %s nread == -1. "
                           "Error = %s\n",
                           aio_ex->fsp->fsp_name, strerror(errno) ));

                ret = errno;
                ERROR_NT(map_nt_error_from_unix(ret));
                outsize = srv_set_message(outbuf,0,0,true);
        } else {
                outsize = srv_set_message(outbuf,12,nread,False);
                SSVAL(outbuf,smb_vwv2,0xFFFF); /* Remaining - must be * -1. */
                SSVAL(outbuf,smb_vwv5,nread);
                SSVAL(outbuf,smb_vwv6,smb_offset(data,outbuf));
                SSVAL(outbuf,smb_vwv7,((nread >> 16) & 1));
                SSVAL(smb_buf(outbuf),-2,nread);

                aio_ex->fsp->fh->pos = aio_ex->acb.aio_offset + nread;
                aio_ex->fsp->fh->position_information = aio_ex->fsp->fh->pos;

                DEBUG( 3, ( "handle_aio_read_complete file %s max=%d "
                            "nread=%d\n",
                            aio_ex->fsp->fsp_name,
                            (int)aio_ex->acb.aio_nbytes, (int)nread ) );

        }
        smb_setlen(outbuf,outsize - 4);
        show_msg(outbuf);
        if (!srv_send_smb(smbd_server_fd(),outbuf,
                        IS_CONN_ENCRYPTED(aio_ex->fsp->conn))) {
                exit_server_cleanly("handle_aio_read_complete: srv_send_smb "
                                    "failed.");
        }

        DEBUG(10,("handle_aio_read_complete: scheduled aio_read completed "
                  "for file %s, offset %.0f, len = %u\n",
                  aio_ex->fsp->fsp_name, (double)aio_ex->acb.aio_offset,
                  (unsigned int)nread ));

        return ret;
}

/****************************************************************************
 Complete the write and return the data or error back to the client.
 Returns errno or zero if all ok.
*****************************************************************************/

static int handle_aio_write_complete(struct aio_extra *aio_ex)
{
        int ret = 0;
        files_struct *fsp = aio_ex->fsp;
        char *outbuf = aio_ex->outbuf;
        ssize_t numtowrite = aio_ex->acb.aio_nbytes;
        ssize_t nwritten = SMB_VFS_AIO_RETURN(fsp,&aio_ex->acb);

        if (fsp->aio_write_behind) {
                if (nwritten != numtowrite) {
                        if (nwritten == -1) {
                                DEBUG(5,("handle_aio_write_complete: "
                                         "aio_write_behind failed ! File %s "
                                         "is corrupt ! Error %s\n",
                                         fsp->fsp_name, strerror(errno) ));
                                ret = errno;
                        } else {
                                DEBUG(0,("handle_aio_write_complete: "
                                         "aio_write_behind failed ! File %s "
                                         "is corrupt ! Wanted %u bytes but "
                                         "only wrote %d\n", fsp->fsp_name,
                                         (unsigned int)numtowrite,
                                         (int)nwritten ));
                                ret = EIO;
                        }
                } else {
                        DEBUG(10,("handle_aio_write_complete: "
                                  "aio_write_behind completed for file %s\n",
                                  fsp->fsp_name ));
                }
                return 0;
        }

        /* We don't need outsize or set_message here as we've already set the
           fixed size length when we set up the aio call. */

        if(nwritten == -1) {
                DEBUG( 3,( "handle_aio_write: file %s wanted %u bytes. "
                           "nwritten == %d. Error = %s\n",
                           fsp->fsp_name, (unsigned int)numtowrite,
                           (int)nwritten, strerror(errno) ));

                /* If errno is ECANCELED then don't return anything to the
                 * client. */
                if (errno == ECANCELED) {
                        srv_cancel_sign_response(aio_ex->mid);
                        return 0;
                }

                ret = errno;
                ERROR_BOTH(map_nt_error_from_unix(ret), ERRHRD, ERRdiskfull);
                srv_set_message(outbuf,0,0,true);
        } else {
                bool write_through = BITSETW(aio_ex->inbuf+smb_vwv7,0);
                NTSTATUS status;

                SSVAL(outbuf,smb_vwv2,nwritten);
                SSVAL(outbuf,smb_vwv4,(nwritten>>16)&1);
                if (nwritten < (ssize_t)numtowrite) {
                        SCVAL(outbuf,smb_rcls,ERRHRD);
                        SSVAL(outbuf,smb_err,ERRdiskfull);
                }

                DEBUG(3,("handle_aio_write: fnum=%d num=%d wrote=%d\n",
                         fsp->fnum, (int)numtowrite, (int)nwritten));
                status = sync_file(fsp->conn,fsp, write_through);
                if (!NT_STATUS_IS_OK(status)) {
                        ret = errno;
                        ERROR_BOTH(map_nt_error_from_unix(ret),
                                   ERRHRD, ERRdiskfull);
                        srv_set_message(outbuf,0,0,true);
                        DEBUG(5,("handle_aio_write: sync_file for %s returned %s\n",
                                fsp->fsp_name, nt_errstr(status) ));
                }

                aio_ex->fsp->fh->pos = aio_ex->acb.aio_offset + nwritten;
        }

        show_msg(outbuf);
        if (!srv_send_smb(smbd_server_fd(),outbuf,IS_CONN_ENCRYPTED(fsp->conn))) {
                exit_server_cleanly("handle_aio_write: srv_send_smb failed.");
        }

        DEBUG(10,("handle_aio_write_complete: scheduled aio_write completed "
                  "for file %s, offset %.0f, requested %u, written = %u\n",
                  fsp->fsp_name, (double)aio_ex->acb.aio_offset,
                  (unsigned int)numtowrite, (unsigned int)nwritten ));

        return ret;
}

/****************************************************************************
 Handle any aio completion. Returns True if finished (and sets *perr if err
 was non-zero), False if not.
*****************************************************************************/

static bool handle_aio_completed(struct aio_extra *aio_ex, int *perr)
{
        int err;

        if(!aio_ex) {
                DEBUG(3, ("handle_aio_completed: Non-existing aio_ex passed\n"));
                return false;
        }

        /* Ensure the operation has really completed. */
        if (SMB_VFS_AIO_ERROR(aio_ex->fsp, &aio_ex->acb) == EINPROGRESS) {
                DEBUG(10,( "handle_aio_completed: operation mid %u still in "
                           "process for file %s\n",
                           aio_ex->mid, aio_ex->fsp->fsp_name ));
                return False;
        }

        if (aio_ex->read_req) {
                err = handle_aio_read_complete(aio_ex);
        } else {
                err = handle_aio_write_complete(aio_ex);
        }

        if (err) {
                *perr = err; /* Only save non-zero errors. */
        }

        return True;
}

/****************************************************************************
 Handle any aio completion inline.
 Returns non-zero errno if fail or zero if all ok.
*****************************************************************************/

int process_aio_queue(void)
{
        int i;
        int ret = 0;

        BlockSignals(True, RT_SIGNAL_AIO);

        DEBUG(10,("process_aio_queue: signals_received = %d\n",
                  (int)signals_received));
        DEBUG(10,("process_aio_queue: outstanding_aio_calls = %d\n",
                  outstanding_aio_calls));

        if (!signals_received) {
                BlockSignals(False, RT_SIGNAL_AIO);
                return 0;
        }

        /* Drain all the complete aio_reads. */
        for (i = 0; i < signals_received; i++) {
                uint16 mid = aio_pending_array[i];
                files_struct *fsp = NULL;
                struct aio_extra *aio_ex = find_aio_ex(mid);

                if (!aio_ex) {
                        DEBUG(3,("process_aio_queue: Can't find record to "
                                 "match mid %u.\n", (unsigned int)mid));
                        srv_cancel_sign_response(mid);
                        continue;
                }

                fsp = aio_ex->fsp;
                if (fsp == NULL) {
                        /* file was closed whilst I/O was outstanding. Just
                         * ignore. */
                        DEBUG( 3,( "process_aio_queue: file closed whilst "
                                   "aio outstanding.\n"));
                        srv_cancel_sign_response(mid);
                        continue;
                }

                if (!handle_aio_completed(aio_ex, &ret)) {
                        continue;
                }

                delete_aio_ex(aio_ex);
        }

        outstanding_aio_calls -= signals_received;
        signals_received = 0;
        BlockSignals(False, RT_SIGNAL_AIO);
        return ret;
}

/****************************************************************************
 We're doing write behind and the client closed the file. Wait up to 30
 seconds (my arbitrary choice) for the aio to complete. Return 0 if all writes
 completed, errno to return if not.
*****************************************************************************/

#define SMB_TIME_FOR_AIO_COMPLETE_WAIT 29

int wait_for_aio_completion(files_struct *fsp)
{
        struct aio_extra *aio_ex;
        const SMB_STRUCT_AIOCB **aiocb_list;
        int aio_completion_count = 0;
        time_t start_time = time(NULL);
        int seconds_left;

        for (seconds_left = SMB_TIME_FOR_AIO_COMPLETE_WAIT;
             seconds_left >= 0;) {
                int err = 0;
                int i;
                struct timespec ts;

                aio_completion_count = 0;
                for( aio_ex = aio_list_head; aio_ex; aio_ex = aio_ex->next) {
                        if (aio_ex->fsp == fsp) {
                                aio_completion_count++;
                        }
                }

                if (!aio_completion_count) {
                        return 0;
                }

                DEBUG(3,("wait_for_aio_completion: waiting for %d aio events "
                         "to complete.\n", aio_completion_count ));

                aiocb_list = SMB_MALLOC_ARRAY(const SMB_STRUCT_AIOCB *,
                                              aio_completion_count);
                if (!aiocb_list) {
                        return ENOMEM;
                }

                for( i = 0, aio_ex = aio_list_head;
                     aio_ex;
                     aio_ex = aio_ex->next) {
                        if (aio_ex->fsp == fsp) {
                                aiocb_list[i++] = &aio_ex->acb;
                        }
                }

                /* Now wait up to seconds_left for completion. */
                ts.tv_sec = seconds_left;
                ts.tv_nsec = 0;

                DEBUG(10,("wait_for_aio_completion: %d events, doing a wait "
                          "of %d seconds.\n",
                          aio_completion_count, seconds_left ));

                err = SMB_VFS_AIO_SUSPEND(fsp, aiocb_list,
                                          aio_completion_count, &ts);

                DEBUG(10,("wait_for_aio_completion: returned err = %d, "
                          "errno = %s\n", err, strerror(errno) ));
                
                if (err == -1 && errno == EAGAIN) {
                        DEBUG(0,("wait_for_aio_completion: aio_suspend timed "
                                 "out waiting for %d events after a wait of "
                                 "%d seconds\n", aio_completion_count,
                                 seconds_left));
                        /* Timeout. */
                        cancel_aio_by_fsp(fsp);
                        SAFE_FREE(aiocb_list);
                        return EIO;
                }

                /* One or more events might have completed - process them if
                 * so. */
                for( i = 0; i < aio_completion_count; i++) {
                        uint16 mid = aiocb_list[i]->aio_sigevent.sigev_value.sival_int;

                        aio_ex = find_aio_ex(mid);

                        if (!aio_ex) {
                                DEBUG(0, ("wait_for_aio_completion: mid %u "
                                          "doesn't match an aio record\n",
                                          (unsigned int)mid ));
                                continue;
                        }

                        if (!handle_aio_completed(aio_ex, &err)) {
                                continue;
                        }
                        delete_aio_ex(aio_ex);
                }

                SAFE_FREE(aiocb_list);
                seconds_left = SMB_TIME_FOR_AIO_COMPLETE_WAIT
                        - (time(NULL) - start_time);
        }

        /* We timed out - we don't know why. Return ret if already an error,
         * else EIO. */
        DEBUG(10,("wait_for_aio_completion: aio_suspend timed out waiting "
                  "for %d events\n",
                  aio_completion_count));

        return EIO;
}

/****************************************************************************
 Cancel any outstanding aio requests. The client doesn't care about the reply.
*****************************************************************************/

void cancel_aio_by_fsp(files_struct *fsp)
{
        struct aio_extra *aio_ex;

        for( aio_ex = aio_list_head; aio_ex; aio_ex = aio_ex->next) {
                if (aio_ex->fsp == fsp) {
                        /* Don't delete the aio_extra record as we may have
                           completed and don't yet know it. Just do the
                           aio_cancel call and return. */
                        SMB_VFS_AIO_CANCEL(fsp, &aio_ex->acb);
                        aio_ex->fsp = NULL; /* fsp will be closed when we
                                             * return. */
                }
        }
}

#else
bool aio_finished(void)
{
        return False;
}

void initialize_async_io_handler(void)
{
}

int process_aio_queue(void)
{
        return False;
}

bool schedule_aio_read_and_X(connection_struct *conn,
                             struct smb_request *req,
                             files_struct *fsp, SMB_OFF_T startpos,
                             size_t smb_maxcnt)
{
        return False;
}

bool schedule_aio_write_and_X(connection_struct *conn,
                              struct smb_request *req,
                              files_struct *fsp, char *data,
                              SMB_OFF_T startpos,
                              size_t numtowrite)
{
        return False;
}

void cancel_aio_by_fsp(files_struct *fsp)
{
}

int wait_for_aio_completion(files_struct *fsp)
{
        return ENOSYS;
}
#endif