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[Samba.git] / source3 / modules / vfs_aio_pthread.c

/*
 * Simulate Posix AIO using pthreads.
 *
 * Based on the aio_fork work from Volker and Volker's pthreadpool library.
 *
 * Copyright (C) Volker Lendecke 2008
 * Copyright (C) Jeremy Allison 2012
 *
 * 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, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include "includes.h"
#include "system/filesys.h"
#include "system/shmem.h"
#include "smbd/smbd.h"
#include "lib/pthreadpool/pthreadpool.h"

struct aio_extra;
static struct pthreadpool *pool;
static int aio_pthread_jobid;

struct aio_private_data {
        struct aio_private_data *prev, *next;
        int jobid;
        SMB_STRUCT_AIOCB *aiocb;
        ssize_t ret_size;
        int ret_errno;
        bool cancelled;
        bool write_command;
};

/* List of outstanding requests we have. */
static struct aio_private_data *pd_list;

static void aio_pthread_handle_completion(struct event_context *event_ctx,
                                struct fd_event *event,
                                uint16 flags,
                                void *p);

/************************************************************************
 How many threads to initialize ?
 100 per process seems insane as a default until you realize that
 (a) Threads terminate after 1 second when idle.
 (b) Throttling is done in SMB2 via the crediting algorithm.
 (c) SMB1 clients are limited to max_mux (50) outstanding requests and
     Windows clients don't use this anyway.
 Essentially we want this to be unlimited unless smb.conf says different.
***********************************************************************/

static int aio_get_num_threads(struct vfs_handle_struct *handle)
{
        return lp_parm_int(SNUM(handle->conn),
                           "aio_pthread", "aio num threads", 100);
}

/************************************************************************
 Ensure thread pool is initialized.
***********************************************************************/

static bool init_aio_threadpool(struct vfs_handle_struct *handle)
{
        struct fd_event *sock_event = NULL;
        int ret = 0;
        int num_threads;
        int fd;

        if (pool) {
                return true;
        }

        num_threads = aio_get_num_threads(handle);
        ret = pthreadpool_init(num_threads, &pool);
        if (ret) {
                errno = ret;
                return false;
        }

        fd = pthreadpool_signal_fd(pool);

        set_blocking(fd, false);

        sock_event = tevent_add_fd(server_event_context(),
                                NULL,
                                fd,
                                TEVENT_FD_READ,
                                aio_pthread_handle_completion,
                                NULL);
        if (sock_event == NULL) {
                pthreadpool_destroy(pool);
                pool = NULL;
                return false;
        }

        DEBUG(10,("init_aio_threadpool: initialized with up to %d threads\n",
                        num_threads));

        return true;
}


/************************************************************************
 Worker function - core of the pthread aio engine.
 This is the function that actually does the IO.
***********************************************************************/

static void aio_worker(void *private_data)
{
        struct aio_private_data *pd =
                        (struct aio_private_data *)private_data;

        if (pd->write_command) {
                pd->ret_size = sys_pwrite(pd->aiocb->aio_fildes,
                                (const void *)pd->aiocb->aio_buf,
                                pd->aiocb->aio_nbytes,
                                pd->aiocb->aio_offset);
                if (pd->ret_size == -1 && errno == ESPIPE) {
                        /* Maintain the fiction that pipes can
                           be seeked (sought?) on. */
                        pd->ret_size = sys_write(pd->aiocb->aio_fildes,
                                        (const void *)pd->aiocb->aio_buf,
                                        pd->aiocb->aio_nbytes);
                }
        } else {
                pd->ret_size = sys_pread(pd->aiocb->aio_fildes,
                                (void *)pd->aiocb->aio_buf,
                                pd->aiocb->aio_nbytes,
                                pd->aiocb->aio_offset);
                if (pd->ret_size == -1 && errno == ESPIPE) {
                        /* Maintain the fiction that pipes can
                           be seeked (sought?) on. */
                        pd->ret_size = sys_read(pd->aiocb->aio_fildes,
                                        (void *)pd->aiocb->aio_buf,
                                        pd->aiocb->aio_nbytes);
                }
        }
        if (pd->ret_size == -1) {
                pd->ret_errno = errno;
        } else {
                pd->ret_errno = 0;
        }
}

/************************************************************************
 Private data destructor.
***********************************************************************/

static int pd_destructor(struct aio_private_data *pd)
{
        DLIST_REMOVE(pd_list, pd);
        return 0;
}

/************************************************************************
 Create and initialize a private data struct.
***********************************************************************/

static struct aio_private_data *create_private_data(TALLOC_CTX *ctx,
                                        SMB_STRUCT_AIOCB *aiocb)
{
        struct aio_private_data *pd = talloc_zero(ctx, struct aio_private_data);
        if (!pd) {
                return NULL;
        }
        pd->jobid = aio_pthread_jobid++;
        pd->aiocb = aiocb;
        pd->ret_size = -1;
        pd->ret_errno = EINPROGRESS;
        talloc_set_destructor(pd, pd_destructor);
        DLIST_ADD_END(pd_list, pd, struct aio_private_data *);
        return pd;
}

/************************************************************************
 Spin off a threadpool (if needed) and initiate a pread call.
***********************************************************************/

static int aio_pthread_read(struct vfs_handle_struct *handle,
                                struct files_struct *fsp,
                                SMB_STRUCT_AIOCB *aiocb)
{
        struct aio_extra *aio_ex = (struct aio_extra *)aiocb->aio_sigevent.sigev_value.sival_ptr;
        struct aio_private_data *pd = NULL;
        int ret;

        if (!init_aio_threadpool(handle)) {
                return -1;
        }

        pd = create_private_data(aio_ex, aiocb);
        if (pd == NULL) {
                DEBUG(10, ("aio_pthread_read: Could not create private data.\n"));
                return -1;
        }

        ret = pthreadpool_add_job(pool, pd->jobid, aio_worker, (void *)pd);
        if (ret) {
                errno = ret;
                return -1;
        }

        DEBUG(10, ("aio_pthread_read: jobid=%d pread requested "
                "of %llu bytes at offset %llu\n",
                pd->jobid,
                (unsigned long long)pd->aiocb->aio_nbytes,
                (unsigned long long)pd->aiocb->aio_offset));

        return 0;
}

/************************************************************************
 Spin off a threadpool (if needed) and initiate a pwrite call.
***********************************************************************/

static int aio_pthread_write(struct vfs_handle_struct *handle,
                                struct files_struct *fsp,
                                SMB_STRUCT_AIOCB *aiocb)
{
        struct aio_extra *aio_ex = (struct aio_extra *)aiocb->aio_sigevent.sigev_value.sival_ptr;
        struct aio_private_data *pd = NULL;
        int ret;

        if (!init_aio_threadpool(handle)) {
                return -1;
        }

        pd = create_private_data(aio_ex, aiocb);
        if (pd == NULL) {
                DEBUG(10, ("aio_pthread_write: Could not create private data.\n"));
                return -1;
        }

        pd->write_command = true;

        ret = pthreadpool_add_job(pool, pd->jobid, aio_worker, (void *)pd);
        if (ret) {
                errno = ret;
                return -1;
        }

        DEBUG(10, ("aio_pthread_write: jobid=%d pwrite requested "
                "of %llu bytes at offset %llu\n",
                pd->jobid,
                (unsigned long long)pd->aiocb->aio_nbytes,
                (unsigned long long)pd->aiocb->aio_offset));

        return 0;
}

/************************************************************************
 Find the private data by jobid.
***********************************************************************/

static struct aio_private_data *find_private_data_by_jobid(int jobid)
{
        struct aio_private_data *pd;

        for (pd = pd_list; pd != NULL; pd = pd->next) {
                if (pd->jobid == jobid) {
                        return pd;
                }
        }

        return NULL;
}

/************************************************************************
 Callback when an IO completes.
***********************************************************************/

static void aio_pthread_handle_completion(struct event_context *event_ctx,
                                struct fd_event *event,
                                uint16 flags,
                                void *p)
{
        struct aio_extra *aio_ex = NULL;
        struct aio_private_data *pd = NULL;
        int jobid = 0;
        int ret;

        DEBUG(10, ("aio_pthread_handle_completion called with flags=%d\n",
                        (int)flags));

        if ((flags & EVENT_FD_READ) == 0) {
                return;
        }

        while (true) {
                ret = pthreadpool_finished_job(pool, &jobid);

                if (ret == EINTR || ret == EAGAIN) {
                        return;
                }
#ifdef EWOULDBLOCK
                if (ret == EWOULDBLOCK) {
                        return;
                }
#endif

                if (ret == ECANCELED) {
                        return;
                }

                if (ret) {
                        smb_panic("aio_pthread_handle_completion");
                        return;
                }

                pd = find_private_data_by_jobid(jobid);
                if (pd == NULL) {
                        DEBUG(1, ("aio_pthread_handle_completion cannot find "
                                  "jobid %d\n", jobid));
                        return;
                }

                aio_ex = (struct aio_extra *)
                        pd->aiocb->aio_sigevent.sigev_value.sival_ptr;

                smbd_aio_complete_aio_ex(aio_ex);

                DEBUG(10,("aio_pthread_handle_completion: jobid %d "
                          "completed\n", jobid ));
                TALLOC_FREE(aio_ex);
        }
}

/************************************************************************
 Find the private data by aiocb.
***********************************************************************/

static struct aio_private_data *find_private_data_by_aiocb(SMB_STRUCT_AIOCB *aiocb)
{
        struct aio_private_data *pd;

        for (pd = pd_list; pd != NULL; pd = pd->next) {
                if (pd->aiocb == aiocb) {
                        return pd;
                }
        }

        return NULL;
}

/************************************************************************
 Called to return the result of a completed AIO.
 Should only be called if aio_error returns something other than EINPROGRESS.
 Returns:
        Any other value - return from IO operation.
***********************************************************************/

static ssize_t aio_pthread_return_fn(struct vfs_handle_struct *handle,
                                struct files_struct *fsp,
                                SMB_STRUCT_AIOCB *aiocb)
{
        struct aio_private_data *pd = find_private_data_by_aiocb(aiocb);

        if (pd == NULL) {
                errno = EINVAL;
                DEBUG(0, ("aio_pthread_return_fn: returning EINVAL\n"));
                return -1;
        }

        pd->aiocb = NULL;

        if (pd->ret_size == -1) {
                errno = pd->ret_errno;
        }

        return pd->ret_size;
}

/************************************************************************
 Called to check the result of an AIO.
 Returns:
        EINPROGRESS - still in progress.
        EINVAL - invalid aiocb.
        ECANCELED - request was cancelled.
        0 - request completed successfully.
        Any other value - errno from IO operation.
***********************************************************************/

static int aio_pthread_error_fn(struct vfs_handle_struct *handle,
                             struct files_struct *fsp,
                             SMB_STRUCT_AIOCB *aiocb)
{
        struct aio_private_data *pd = find_private_data_by_aiocb(aiocb);

        if (pd == NULL) {
                return EINVAL;
        }
        if (pd->cancelled) {
                return ECANCELED;
        }
        return pd->ret_errno;
}

/************************************************************************
 Called to request the cancel of an AIO, or all of them on a specific
 fsp if aiocb == NULL.
***********************************************************************/

static int aio_pthread_cancel(struct vfs_handle_struct *handle,
                        struct files_struct *fsp,
                        SMB_STRUCT_AIOCB *aiocb)
{
        struct aio_private_data *pd = NULL;

        for (pd = pd_list; pd != NULL; pd = pd->next) {
                if (pd->aiocb == NULL) {
                        continue;
                }
                if (pd->aiocb->aio_fildes != fsp->fh->fd) {
                        continue;
                }
                if ((aiocb != NULL) && (pd->aiocb != aiocb)) {
                        continue;
                }

                /*
                 * We let the child do its job, but we discard the result when
                 * it's finished.
                 */

                pd->cancelled = true;
        }

        return AIO_CANCELED;
}

/************************************************************************
 Callback for a previously detected job completion.
***********************************************************************/

static void aio_pthread_handle_immediate(struct tevent_context *ctx,
                                struct tevent_immediate *im,
                                void *private_data)
{
        struct aio_extra *aio_ex = NULL;
        int *pjobid = (int *)private_data;
        struct aio_private_data *pd = find_private_data_by_jobid(*pjobid);

        if (pd == NULL) {
                DEBUG(1, ("aio_pthread_handle_immediate cannot find jobid %d\n",
                          *pjobid));
                TALLOC_FREE(pjobid);
                return;
        }

        TALLOC_FREE(pjobid);
        aio_ex = (struct aio_extra *)pd->aiocb->aio_sigevent.sigev_value.sival_ptr;
        smbd_aio_complete_aio_ex(aio_ex);
        TALLOC_FREE(aio_ex);
}

/************************************************************************
 Private data struct used in suspend completion code.
***********************************************************************/

struct suspend_private {
        int num_entries;
        int num_finished;
        const SMB_STRUCT_AIOCB * const *aiocb_array;
};

/************************************************************************
 Callback when an IO completes from a suspend call.
***********************************************************************/

static void aio_pthread_handle_suspend_completion(struct event_context *event_ctx,
                                struct fd_event *event,
                                uint16 flags,
                                void *p)
{
        struct suspend_private *sp = (struct suspend_private *)p;
        struct aio_private_data *pd = NULL;
        struct tevent_immediate *im = NULL;
        int *pjobid = NULL;
        int i;

        DEBUG(10, ("aio_pthread_handle_suspend_completion called with flags=%d\n",
                        (int)flags));

        if ((flags & EVENT_FD_READ) == 0) {
                return;
        }

        pjobid = talloc_array(NULL, int, 1);
        if (pjobid == NULL) {
                smb_panic("aio_pthread_handle_suspend_completion: no memory.");
        }

        if (pthreadpool_finished_job(pool, pjobid)) {
                smb_panic("aio_pthread_handle_suspend_completion: can't find job.");
                return;
        }

        pd = find_private_data_by_jobid(*pjobid);
        if (pd == NULL) {
                DEBUG(1, ("aio_pthread_handle_completion cannot find jobid %d\n",
                          *pjobid));
                TALLOC_FREE(pjobid);
                return;
        }

        /* Is this a jobid with an aiocb we're interested in ? */
        for (i = 0; i < sp->num_entries; i++) {
                if (sp->aiocb_array[i] == pd->aiocb) {
                        sp->num_finished++;
                        TALLOC_FREE(pjobid);
                        return;
                }
        }

        /* Jobid completed we weren't waiting for.
           We must reshedule this as an immediate event
           on the main event context. */
        im = tevent_create_immediate(NULL);
        if (!im) {
                exit_server_cleanly("aio_pthread_handle_suspend_completion: no memory");
        }

        DEBUG(10,("aio_pthread_handle_suspend_completion: "
                        "re-scheduling job id %d\n",
                        *pjobid));

        tevent_schedule_immediate(im,
                        server_event_context(),
                        aio_pthread_handle_immediate,
                        (void *)pjobid);
}


static void aio_pthread_suspend_timed_out(struct tevent_context *event_ctx,
                                        struct tevent_timer *te,
                                        struct timeval now,
                                        void *private_data)
{
        bool *timed_out = (bool *)private_data;
        /* Remove this timed event handler. */
        TALLOC_FREE(te);
        *timed_out = true;
}

/************************************************************************
 Called to request everything to stop until all IO is completed.
***********************************************************************/

static int aio_pthread_suspend(struct vfs_handle_struct *handle,
                        struct files_struct *fsp,
                        const SMB_STRUCT_AIOCB * const aiocb_array[],
                        int n,
                        const struct timespec *timeout)
{
        struct event_context *ev = NULL;
        struct fd_event *sock_event = NULL;
        int ret = -1;
        struct suspend_private sp;
        bool timed_out = false;
        TALLOC_CTX *frame = talloc_stackframe();

        /* This is a blocking call, and has to use a sub-event loop. */
        ev = event_context_init(frame);
        if (ev == NULL) {
                errno = ENOMEM;
                goto out;
        }

        if (timeout) {
                struct timeval tv = convert_timespec_to_timeval(*timeout);
                struct tevent_timer *te = tevent_add_timer(ev,
                                                frame,
                                                timeval_current_ofs(tv.tv_sec,
                                                                    tv.tv_usec),
                                                aio_pthread_suspend_timed_out,
                                                &timed_out);
                if (!te) {
                        errno = ENOMEM;
                        goto out;
                }
        }

        ZERO_STRUCT(sp);
        sp.num_entries = n;
        sp.aiocb_array = aiocb_array;
        sp.num_finished = 0;

        sock_event = tevent_add_fd(ev,
                                frame,
                                pthreadpool_signal_fd(pool),
                                TEVENT_FD_READ,
                                aio_pthread_handle_suspend_completion,
                                (void *)&sp);
        if (sock_event == NULL) {
                pthreadpool_destroy(pool);
                pool = NULL;
                goto out;
        }
        /*
         * We're going to cheat here. We know that smbd/aio.c
         * only calls this when it's waiting for every single
         * outstanding call to finish on a close, so just wait
         * individually for each IO to complete. We don't care
         * what order they finish - only that they all do. JRA.
         */
        while (sp.num_entries != sp.num_finished) {
                if (tevent_loop_once(ev) == -1) {
                        goto out;
                }

                if (timed_out) {
                        errno = EAGAIN;
                        goto out;
                }
        }

        ret = 0;

  out:

        TALLOC_FREE(frame);
        return ret;
}

static struct vfs_fn_pointers vfs_aio_pthread_fns = {
        .aio_read = aio_pthread_read,
        .aio_write = aio_pthread_write,
        .aio_return_fn = aio_pthread_return_fn,
        .aio_cancel = aio_pthread_cancel,
        .aio_error_fn = aio_pthread_error_fn,
        .aio_suspend = aio_pthread_suspend,
};

NTSTATUS vfs_aio_pthread_init(void);
NTSTATUS vfs_aio_pthread_init(void)
{
        return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
                                "aio_pthread", &vfs_aio_pthread_fns);
}