* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
+#include "qemu/osdep.h"
#include "qemu-common.h"
-#include "qemu-aio.h"
-#include "qemu-queue.h"
+#include "block/aio.h"
+#include "qemu/queue.h"
+#include "block/block.h"
#include "block/raw-aio.h"
-#include "event_notifier.h"
+#include "qemu/event_notifier.h"
+#include "qemu/coroutine.h"
#include <libaio.h>
*/
#define MAX_EVENTS 128
+#define MAX_QUEUED_IO 128
+
struct qemu_laiocb {
- BlockDriverAIOCB common;
- struct qemu_laio_state *ctx;
+ BlockAIOCB common;
+ Coroutine *co;
+ LinuxAioState *ctx;
struct iocb iocb;
ssize_t ret;
size_t nbytes;
QEMUIOVector *qiov;
bool is_read;
- QLIST_ENTRY(qemu_laiocb) node;
+ QSIMPLEQ_ENTRY(qemu_laiocb) next;
};
-struct qemu_laio_state {
+typedef struct {
+ int plugged;
+ unsigned int n;
+ bool blocked;
+ QSIMPLEQ_HEAD(, qemu_laiocb) pending;
+} LaioQueue;
+
+struct LinuxAioState {
io_context_t ctx;
EventNotifier e;
- int count;
+
+ /* io queue for submit at batch */
+ LaioQueue io_q;
+
+ /* I/O completion processing */
+ QEMUBH *completion_bh;
+ struct io_event events[MAX_EVENTS];
+ int event_idx;
+ int event_max;
};
+static void ioq_submit(LinuxAioState *s);
+
static inline ssize_t io_event_ret(struct io_event *ev)
{
return (ssize_t)(((uint64_t)ev->res2 << 32) | ev->res);
/*
* Completes an AIO request (calls the callback and frees the ACB).
*/
-static void qemu_laio_process_completion(struct qemu_laio_state *s,
- struct qemu_laiocb *laiocb)
+static void qemu_laio_process_completion(struct qemu_laiocb *laiocb)
{
int ret;
- s->count--;
-
ret = laiocb->ret;
if (ret != -ECANCELED) {
if (ret == laiocb->nbytes) {
ret = -EINVAL;
}
}
+ }
+ laiocb->ret = ret;
+ if (laiocb->co) {
+ qemu_coroutine_enter(laiocb->co, NULL);
+ } else {
laiocb->common.cb(laiocb->common.opaque, ret);
+ qemu_aio_unref(laiocb);
}
-
- qemu_aio_release(laiocb);
}
-static void qemu_laio_completion_cb(EventNotifier *e)
+/* The completion BH fetches completed I/O requests and invokes their
+ * callbacks.
+ *
+ * The function is somewhat tricky because it supports nested event loops, for
+ * example when a request callback invokes aio_poll(). In order to do this,
+ * the completion events array and index are kept in LinuxAioState. The BH
+ * reschedules itself as long as there are completions pending so it will
+ * either be called again in a nested event loop or will be called after all
+ * events have been completed. When there are no events left to complete, the
+ * BH returns without rescheduling.
+ */
+static void qemu_laio_completion_bh(void *opaque)
{
- struct qemu_laio_state *s = container_of(e, struct qemu_laio_state, e);
-
- while (event_notifier_test_and_clear(&s->e)) {
- struct io_event events[MAX_EVENTS];
- struct timespec ts = { 0 };
- int nevents, i;
+ LinuxAioState *s = opaque;
+ /* Fetch more completion events when empty */
+ if (s->event_idx == s->event_max) {
do {
- nevents = io_getevents(s->ctx, MAX_EVENTS, MAX_EVENTS, events, &ts);
- } while (nevents == -EINTR);
+ struct timespec ts = { 0 };
+ s->event_max = io_getevents(s->ctx, MAX_EVENTS, MAX_EVENTS,
+ s->events, &ts);
+ } while (s->event_max == -EINTR);
+
+ s->event_idx = 0;
+ if (s->event_max <= 0) {
+ s->event_max = 0;
+ return; /* no more events */
+ }
+ }
- for (i = 0; i < nevents; i++) {
- struct iocb *iocb = events[i].obj;
- struct qemu_laiocb *laiocb =
- container_of(iocb, struct qemu_laiocb, iocb);
+ /* Reschedule so nested event loops see currently pending completions */
+ qemu_bh_schedule(s->completion_bh);
- laiocb->ret = io_event_ret(&events[i]);
- qemu_laio_process_completion(s, laiocb);
- }
+ /* Process completion events */
+ while (s->event_idx < s->event_max) {
+ struct iocb *iocb = s->events[s->event_idx].obj;
+ struct qemu_laiocb *laiocb =
+ container_of(iocb, struct qemu_laiocb, iocb);
+
+ laiocb->ret = io_event_ret(&s->events[s->event_idx]);
+ s->event_idx++;
+
+ qemu_laio_process_completion(laiocb);
+ }
+
+ if (!s->io_q.plugged && !QSIMPLEQ_EMPTY(&s->io_q.pending)) {
+ ioq_submit(s);
}
+
+ qemu_bh_cancel(s->completion_bh);
}
-static int qemu_laio_flush_cb(EventNotifier *e)
+static void qemu_laio_completion_cb(EventNotifier *e)
{
- struct qemu_laio_state *s = container_of(e, struct qemu_laio_state, e);
+ LinuxAioState *s = container_of(e, LinuxAioState, e);
- return (s->count > 0) ? 1 : 0;
+ if (event_notifier_test_and_clear(&s->e)) {
+ qemu_laio_completion_bh(s);
+ }
}
-static void laio_cancel(BlockDriverAIOCB *blockacb)
+static void laio_cancel(BlockAIOCB *blockacb)
{
struct qemu_laiocb *laiocb = (struct qemu_laiocb *)blockacb;
struct io_event event;
int ret;
- if (laiocb->ret != -EINPROGRESS)
+ if (laiocb->ret != -EINPROGRESS) {
return;
-
- /*
- * Note that as of Linux 2.6.31 neither the block device code nor any
- * filesystem implements cancellation of AIO request.
- * Thus the polling loop below is the normal code path.
- */
+ }
ret = io_cancel(laiocb->ctx->ctx, &laiocb->iocb, &event);
- if (ret == 0) {
- laiocb->ret = -ECANCELED;
+ laiocb->ret = -ECANCELED;
+ if (ret != 0) {
+ /* iocb is not cancelled, cb will be called by the event loop later */
return;
}
- /*
- * We have to wait for the iocb to finish.
- *
- * The only way to get the iocb status update is by polling the io context.
- * We might be able to do this slightly more optimal by removing the
- * O_NONBLOCK flag.
- */
- while (laiocb->ret == -EINPROGRESS) {
- qemu_laio_completion_cb(&laiocb->ctx->e);
- }
+ laiocb->common.cb(laiocb->common.opaque, laiocb->ret);
}
-static AIOPool laio_pool = {
+static const AIOCBInfo laio_aiocb_info = {
.aiocb_size = sizeof(struct qemu_laiocb),
- .cancel = laio_cancel,
+ .cancel_async = laio_cancel,
};
-BlockDriverAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx, int fd,
- int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
- BlockDriverCompletionFunc *cb, void *opaque, int type)
+static void ioq_init(LaioQueue *io_q)
{
- struct qemu_laio_state *s = aio_ctx;
- struct qemu_laiocb *laiocb;
- struct iocb *iocbs;
- off_t offset = sector_num * 512;
+ QSIMPLEQ_INIT(&io_q->pending);
+ io_q->plugged = 0;
+ io_q->n = 0;
+ io_q->blocked = false;
+}
- laiocb = qemu_aio_get(&laio_pool, bs, cb, opaque);
- laiocb->nbytes = nb_sectors * 512;
- laiocb->ctx = s;
- laiocb->ret = -EINPROGRESS;
- laiocb->is_read = (type == QEMU_AIO_READ);
- laiocb->qiov = qiov;
+static void ioq_submit(LinuxAioState *s)
+{
+ int ret, len;
+ struct qemu_laiocb *aiocb;
+ struct iocb *iocbs[MAX_QUEUED_IO];
+ QSIMPLEQ_HEAD(, qemu_laiocb) completed;
+
+ do {
+ len = 0;
+ QSIMPLEQ_FOREACH(aiocb, &s->io_q.pending, next) {
+ iocbs[len++] = &aiocb->iocb;
+ if (len == MAX_QUEUED_IO) {
+ break;
+ }
+ }
+
+ ret = io_submit(s->ctx, len, iocbs);
+ if (ret == -EAGAIN) {
+ break;
+ }
+ if (ret < 0) {
+ abort();
+ }
+
+ s->io_q.n -= ret;
+ aiocb = container_of(iocbs[ret - 1], struct qemu_laiocb, iocb);
+ QSIMPLEQ_SPLIT_AFTER(&s->io_q.pending, aiocb, next, &completed);
+ } while (ret == len && !QSIMPLEQ_EMPTY(&s->io_q.pending));
+ s->io_q.blocked = (s->io_q.n > 0);
+}
- iocbs = &laiocb->iocb;
+void laio_io_plug(BlockDriverState *bs, LinuxAioState *s)
+{
+ assert(!s->io_q.plugged);
+ s->io_q.plugged = 1;
+}
+
+void laio_io_unplug(BlockDriverState *bs, LinuxAioState *s)
+{
+ assert(s->io_q.plugged);
+ s->io_q.plugged = 0;
+ if (!s->io_q.blocked && !QSIMPLEQ_EMPTY(&s->io_q.pending)) {
+ ioq_submit(s);
+ }
+}
+
+static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset,
+ int type)
+{
+ LinuxAioState *s = laiocb->ctx;
+ struct iocb *iocbs = &laiocb->iocb;
+ QEMUIOVector *qiov = laiocb->qiov;
switch (type) {
case QEMU_AIO_WRITE:
default:
fprintf(stderr, "%s: invalid AIO request type 0x%x.\n",
__func__, type);
- goto out_free_aiocb;
+ return -EIO;
}
io_set_eventfd(&laiocb->iocb, event_notifier_get_fd(&s->e));
- s->count++;
- if (io_submit(s->ctx, 1, &iocbs) < 0)
- goto out_dec_count;
+ QSIMPLEQ_INSERT_TAIL(&s->io_q.pending, laiocb, next);
+ s->io_q.n++;
+ if (!s->io_q.blocked &&
+ (!s->io_q.plugged || s->io_q.n >= MAX_QUEUED_IO)) {
+ ioq_submit(s);
+ }
+
+ return 0;
+}
+
+int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
+ uint64_t offset, QEMUIOVector *qiov, int type)
+{
+ int ret;
+ struct qemu_laiocb laiocb = {
+ .co = qemu_coroutine_self(),
+ .nbytes = qiov->size,
+ .ctx = s,
+ .is_read = (type == QEMU_AIO_READ),
+ .qiov = qiov,
+ };
+
+ ret = laio_do_submit(fd, &laiocb, offset, type);
+ if (ret < 0) {
+ return ret;
+ }
+
+ qemu_coroutine_yield();
+ return laiocb.ret;
+}
+
+BlockAIOCB *laio_submit(BlockDriverState *bs, LinuxAioState *s, int fd,
+ int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+ BlockCompletionFunc *cb, void *opaque, int type)
+{
+ struct qemu_laiocb *laiocb;
+ off_t offset = sector_num * BDRV_SECTOR_SIZE;
+ int ret;
+
+ laiocb = qemu_aio_get(&laio_aiocb_info, bs, cb, opaque);
+ laiocb->nbytes = nb_sectors * BDRV_SECTOR_SIZE;
+ laiocb->ctx = s;
+ laiocb->ret = -EINPROGRESS;
+ laiocb->is_read = (type == QEMU_AIO_READ);
+ laiocb->qiov = qiov;
+
+ ret = laio_do_submit(fd, laiocb, offset, type);
+ if (ret < 0) {
+ qemu_aio_unref(laiocb);
+ return NULL;
+ }
+
return &laiocb->common;
+}
-out_dec_count:
- s->count--;
-out_free_aiocb:
- qemu_aio_release(laiocb);
- return NULL;
+void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context)
+{
+ aio_set_event_notifier(old_context, &s->e, false, NULL);
+ qemu_bh_delete(s->completion_bh);
}
-void *laio_init(void)
+void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context)
{
- struct qemu_laio_state *s;
+ s->completion_bh = aio_bh_new(new_context, qemu_laio_completion_bh, s);
+ aio_set_event_notifier(new_context, &s->e, false,
+ qemu_laio_completion_cb);
+}
+
+LinuxAioState *laio_init(void)
+{
+ LinuxAioState *s;
s = g_malloc0(sizeof(*s));
if (event_notifier_init(&s->e, false) < 0) {
goto out_close_efd;
}
- qemu_aio_set_event_notifier(&s->e, qemu_laio_completion_cb,
- qemu_laio_flush_cb);
+ ioq_init(&s->io_q);
return s;
g_free(s);
return NULL;
}
+
+void laio_cleanup(LinuxAioState *s)
+{
+ event_notifier_cleanup(&s->e);
+
+ if (io_destroy(s->ctx) != 0) {
+ fprintf(stderr, "%s: destroy AIO context %p failed\n",
+ __func__, &s->ctx);
+ }
+ g_free(s);
+}
projects / qemu.git / blobdiff