s3-linux-aio: Fix error handling

[Samba/gebeck_regimport.git] / source3 / modules / vfs_aio_linux.c

/*
 * Simulate Posix AIO using Linux kernel AIO.
 *
 * 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 "smbd/smbd.h"
#include "smbd/globals.h"
#include <sys/eventfd.h>
#include <libaio.h>

struct aio_extra;
static int event_fd = -1;
static io_context_t io_ctx;
static int aio_linux_requestid;
static struct io_event *io_recv_events;
static struct fd_event *aio_read_event;

struct aio_private_data {
        struct aio_private_data *prev, *next;
        int requestid;
        SMB_STRUCT_AIOCB *aiocb;
        struct iocb *event_iocb;
        ssize_t ret_size;
        int ret_errno;
        bool cancelled;
};

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

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

/************************************************************************
 Housekeeping. Cleanup if no activity for 30 seconds.
***********************************************************************/

static void aio_linux_housekeeping(struct tevent_context *event_ctx,
                                        struct tevent_timer *te,
                                        struct timeval now,
                                        void *private_data)
{
        /* Remove this timed event handler. */
        TALLOC_FREE(te);

        if (pd_list != NULL) {
                /* Still busy. Look again in 30 seconds. */
                (void)tevent_add_timer(event_ctx,
                                        NULL,
                                        timeval_current_ofs(30, 0),
                                        aio_linux_housekeeping,
                                        NULL);
                return;
        }

        /* No activity for 30 seconds. Close out kernel resources. */
        io_queue_release(io_ctx);
        memset(&io_ctx, '\0', sizeof(io_ctx));

        if (event_fd != -1) {
                close(event_fd);
                event_fd = -1;
        }

        TALLOC_FREE(aio_read_event);
        TALLOC_FREE(io_recv_events);
}

/************************************************************************
 Ensure event fd and aio context are initialized.
***********************************************************************/

static bool init_aio_linux(struct vfs_handle_struct *handle)
{
        struct tevent_timer *te = NULL;

        if (event_fd != -1) {
                /* Already initialized. */
                return true;
        }

        /* Schedule a shutdown event for 30 seconds from now. */
        te = tevent_add_timer(server_event_context(),
                                NULL,
                                timeval_current_ofs(30, 0),
                                aio_linux_housekeeping,
                                NULL);

        if (te == NULL) {
                goto fail;
        }

        /* Ensure we have enough space for aio_pending_size events. */
        io_recv_events = talloc_zero_array(NULL,
                                struct io_event,
                                aio_pending_size);
        if (io_recv_events == NULL) {
                goto fail;
        }

        event_fd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
        if (event_fd == -1) {
                goto fail;
        }

        aio_read_event = tevent_add_fd(server_event_context(),
                                NULL,
                                event_fd,
                                TEVENT_FD_READ,
                                aio_linux_handle_completion,
                                NULL);
        if (aio_read_event == NULL) {
                goto fail;
        }

        if (io_queue_init(aio_pending_size, &io_ctx)) {
                goto fail;
        }

        DEBUG(10,("init_aio_linux: initialized with up to %d events\n",
                  aio_pending_size));

        return true;

  fail:

        DEBUG(10,("init_aio_linux: initialization failed\n"));

        TALLOC_FREE(te);
        TALLOC_FREE(io_recv_events);
        TALLOC_FREE(aio_read_event);
        if (event_fd != -1) {
                close(event_fd);
                event_fd = -1;
        }
        memset(&io_ctx, '\0', sizeof(io_ctx));
        return false;
}

/************************************************************************
 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->event_iocb = talloc_zero(pd, struct iocb);
        pd->requestid = aio_linux_requestid++;
        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;
}

/************************************************************************
 Initiate an asynchronous pread call.
***********************************************************************/

static int aio_linux_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_linux(handle)) {
                return -1;
        }

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

        io_prep_pread(pd->event_iocb,
                        pd->aiocb->aio_fildes,
                        discard_const(pd->aiocb->aio_buf),
                        pd->aiocb->aio_nbytes,
                        pd->aiocb->aio_offset);
        io_set_eventfd(pd->event_iocb, event_fd);
        /* Use the callback pointer as a private data ptr. */
        io_set_callback(pd->event_iocb, (io_callback_t)pd);

        ret = io_submit(io_ctx, 1, &pd->event_iocb);
        if (ret < 0) {
                errno = ret;
                return -1;
        }

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

        return 0;
}

/************************************************************************
 Initiate an asynchronous pwrite call.
***********************************************************************/

static int aio_linux_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_linux(handle)) {
                return -1;
        }

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

        io_prep_pwrite(pd->event_iocb,
                        pd->aiocb->aio_fildes,
                        discard_const(pd->aiocb->aio_buf),
                        pd->aiocb->aio_nbytes,
                        pd->aiocb->aio_offset);
        io_set_eventfd(pd->event_iocb, event_fd);
        /* Use the callback pointer as a private data ptr. */
        io_set_callback(pd->event_iocb, (io_callback_t)pd);

        ret = io_submit(io_ctx, 1, &pd->event_iocb);
        if (ret < 0) {
                errno = ret;
                return -1;
        }

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

        return 0;
}

/************************************************************************
 Save off the error / success conditions from the io_event.
 Is idempotent (can be called multiple times given the same ioev).
***********************************************************************/

static void aio_linux_setup_returns(struct io_event *ioev)
{
        struct aio_private_data *pd = (struct aio_private_data *)ioev->data;

        if (ioev->res < 0) {
                pd->ret_size = -1;
                pd->ret_errno = -ioev->res;
        } else {
                pd->ret_size = ioev->res;
                pd->ret_errno = 0;
        }
}

/************************************************************************
 Handle a single finished io.
***********************************************************************/

static void aio_linux_handle_io_finished(struct io_event *ioev)
{
        struct aio_extra *aio_ex = NULL;
        struct aio_private_data *pd = (struct aio_private_data *)ioev->data;

        aio_linux_setup_returns(ioev);

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

        DEBUG(10,("aio_linux_handle_io_finished: requestid %d completed\n",
                pd->requestid ));
        TALLOC_FREE(aio_ex);
}

/************************************************************************
 Callback when multiple IOs complete.
***********************************************************************/

static void aio_linux_handle_completion(struct event_context *event_ctx,
                                struct fd_event *event,
                                uint16 flags,
                                void *p)
{
        uint64_t num_events = 0;

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

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

        /* Read the number of events available. */
        if (sys_read(event_fd, &num_events, sizeof(num_events)) !=
                        sizeof(num_events)) {
                smb_panic("aio_linux_handle_completion: invalid read");
        }

        while (num_events > 0) {
                uint64_t events_to_read = MIN(num_events, aio_pending_size);
                struct timespec ts;
                int i;
                int ret;

                ts.tv_sec = 0;
                ts.tv_nsec = 0;

                ret = io_getevents(io_ctx,
                        1,
                        (long)events_to_read,
                        io_recv_events,
                        &ts);

                if (ret < 0) {
                        errno = -ret;
                        DEBUG(1, ("aio_linux_handle_completion: "
                                "io_getevents error %s\n",
                                strerror(errno) ));
                        return;
                }

                if (ret == 0) {
                        DEBUG(10, ("aio_linux_handle_completion: "
                                "io_getevents returned 0\n"));
                        continue;
                }

                /* ret is positive. */
                for (i = 0; i < ret; i++) {
                        aio_linux_handle_io_finished(&io_recv_events[i]);
                }

                num_events -= ret;
        }
}

/************************************************************************
 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_linux_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_linux_return_fn: returning EINVAL\n"));
                return -1;
        }

        pd->aiocb = NULL;

        if (pd->cancelled) {
                errno = ECANCELED;
                return -1;
        }

        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_linux_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_linux_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 kernel do its job, but we discard the result when
                 * it's finished. NB. Should I call io_cancel here ?
                 */

                pd->cancelled = true;
        }

        return AIO_CANCELED;
}

/************************************************************************
 Callback for a previously detected job completion deferred to the main
 loop.
***********************************************************************/

static void aio_linux_handle_immediate(struct tevent_context *ctx,
                                struct tevent_immediate *im,
                                void *private_data)
{
        struct io_event *ioev = (struct io_event *)private_data;

        aio_linux_handle_io_finished(ioev);
        TALLOC_FREE(ioev);
}

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

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

/************************************************************************
 Handle a single finished io from suspend.
***********************************************************************/

static void aio_linux_handle_suspend_io_finished(struct suspend_private *sp,
                                                struct io_event *ioev)
{
        struct aio_private_data *pd = (struct aio_private_data *)ioev->data;
        struct io_event *new_ioev = NULL;
        struct tevent_immediate *im = NULL;
        int i;

        /* Is this a requestid 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++;
                        /*
                         * We don't call aio_linux_handle_io_finished()
                         * here, but only the function that sets up the
                         * return values. This allows
                         * aio_linux_handle_io_finished() to be successfully
                         * called from smbd/aio.c:wait_for_aio_completion()
                         * once we return from here with all io's done.
                         */
                        aio_linux_setup_returns(ioev);
                        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_linux_handle_suspend_completion: no memory");
        }

        new_ioev = (struct io_event *)talloc_memdup(NULL,
                                                ioev,
                                                sizeof(struct io_event));
        if (!new_ioev) {
                exit_server_cleanly("aio_linux_handle_suspend_completion: no memory");
        }

        DEBUG(10,("aio_linux_handle_suspend_completion: "
                        "re-scheduling requestid %d\n",
                        pd->requestid));

        tevent_schedule_immediate(im,
                        server_event_context(),
                        aio_linux_handle_immediate,
                        (void *)new_ioev);
}

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

static void aio_linux_handle_suspend_completion(struct event_context *event_ctx,
                                struct fd_event *event,
                                uint16 flags,
                                void *p)
{
        struct suspend_private *sp = (struct suspend_private *)p;
        uint64_t remaining_events = sp->num_entries - sp->num_finished;
        uint64_t num_events = 0;

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

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

        /* Read the number of events available. */
        if (sys_read(event_fd, &num_events, sizeof(num_events)) !=
                        sizeof(num_events)) {
                smb_panic("aio_linux_handle_completion: invalid read");
        }

        while (num_events > 0) {
                uint64_t events_to_read = MIN(num_events, remaining_events);
                struct timespec ts;
                int i;
                int ret;

                ts.tv_sec = 0;
                ts.tv_nsec = 0;

                ret = io_getevents(io_ctx,
                        1,
                        (long)events_to_read,
                        io_recv_events,
                        &ts);

                if (ret < 0) {
                        errno = -ret;
                        DEBUG(1, ("aio_linux_handle_suspend_completion: "
                                "io_getevents error %s\n",
                                strerror(errno) ));
                        return;
                }

                if (ret == 0) {
                        DEBUG(10, ("aio_linux_handle_suspend_completion: "
                                "io_getevents returned 0\n"));
                        continue;
                }

                /* ret is positive. */
                for (i = 0; i < ret; i++) {
                        aio_linux_handle_suspend_io_finished(sp,
                                        &io_recv_events[i]);
                }

                num_events -= ret;
        }
}

static void aio_linux_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_linux_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_linux_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,
                                event_fd,
                                TEVENT_FD_READ,
                                aio_linux_handle_suspend_completion,
                                (void *)&sp);
        if (sock_event == 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 int aio_linux_connect(vfs_handle_struct *handle, const char *service,
                               const char *user)
{
        /*********************************************************************
         * How many io_events to initialize ?
         * 128 per process seems insane as a default until you realize that
         * (a) Throttling is done in SMB2 via the crediting algorithm.
         * (b) 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.
         *********************************************************************/
        aio_pending_size = lp_parm_int(
                SNUM(handle->conn), "aio_linux", "aio num events", 128);
        return SMB_VFS_NEXT_CONNECT(handle, service, user);
}

static struct vfs_fn_pointers vfs_aio_linux_fns = {
        .connect_fn = aio_linux_connect,
        .aio_read_fn = aio_linux_read,
        .aio_write_fn = aio_linux_write,
        .aio_return_fn = aio_linux_return_fn,
        .aio_cancel_fn = aio_linux_cancel,
        .aio_error_fn = aio_linux_error_fn,
        .aio_suspend_fn = aio_linux_suspend,
};

NTSTATUS vfs_aio_linux_init(void)
{
        return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
                                "aio_linux", &vfs_aio_linux_fns);
}