hw/block/dataplane/ioq.c

   1 /*
   2  * Linux AIO request queue
   3  *
   4  * Copyright 2012 IBM, Corp.
   5  * Copyright 2012 Red Hat, Inc. and/or its affiliates
   6  *
   7  * Authors:
   8  *   Stefan Hajnoczi <stefanha@redhat.com>
   9  *
  10  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  11  * See the COPYING file in the top-level directory.
  12  *
  13  */
  14
  15 #include "ioq.h"
  16
  17 void ioq_init(IOQueue *ioq, int fd, unsigned int max_reqs)
  18 {
  19     int rc;
  20
  21     ioq->fd = fd;
  22     ioq->max_reqs = max_reqs;
  23
  24     memset(&ioq->io_ctx, 0, sizeof ioq->io_ctx);
  25     rc = io_setup(max_reqs, &ioq->io_ctx);
  26     if (rc != 0) {
  27         fprintf(stderr, "ioq io_setup failed %d\n", rc);
  28         exit(1);
  29     }
  30
  31     rc = event_notifier_init(&ioq->io_notifier, 0);
  32     if (rc != 0) {
  33         fprintf(stderr, "ioq io event notifier creation failed %d\n", rc);
  34         exit(1);
  35     }
  36
  37     ioq->freelist = g_malloc0(sizeof ioq->freelist[0] * max_reqs);
  38     ioq->freelist_idx = 0;
  39
  40     ioq->queue = g_malloc0(sizeof ioq->queue[0] * max_reqs);
  41     ioq->queue_idx = 0;
  42 }
  43
  44 void ioq_cleanup(IOQueue *ioq)
  45 {
  46     g_free(ioq->freelist);
  47     g_free(ioq->queue);
  48
  49     event_notifier_cleanup(&ioq->io_notifier);
  50     io_destroy(ioq->io_ctx);
  51 }
  52
  53 EventNotifier *ioq_get_notifier(IOQueue *ioq)
  54 {
  55     return &ioq->io_notifier;
  56 }
  57
  58 struct iocb *ioq_get_iocb(IOQueue *ioq)
  59 {
  60     /* Underflow cannot happen since ioq is sized for max_reqs */
  61     assert(ioq->freelist_idx != 0);
  62
  63     struct iocb *iocb = ioq->freelist[--ioq->freelist_idx];
  64     ioq->queue[ioq->queue_idx++] = iocb;
  65     return iocb;
  66 }
  67
  68 void ioq_put_iocb(IOQueue *ioq, struct iocb *iocb)
  69 {
  70     /* Overflow cannot happen since ioq is sized for max_reqs */
  71     assert(ioq->freelist_idx != ioq->max_reqs);
  72
  73     ioq->freelist[ioq->freelist_idx++] = iocb;
  74 }
  75
  76 struct iocb *ioq_rdwr(IOQueue *ioq, bool read, struct iovec *iov,
  77                       unsigned int count, long long offset)
  78 {
  79     struct iocb *iocb = ioq_get_iocb(ioq);
  80
  81     if (read) {
  82         io_prep_preadv(iocb, ioq->fd, iov, count, offset);
  83     } else {
  84         io_prep_pwritev(iocb, ioq->fd, iov, count, offset);
  85     }
  86     io_set_eventfd(iocb, event_notifier_get_fd(&ioq->io_notifier));
  87     return iocb;
  88 }
  89
  90 int ioq_submit(IOQueue *ioq)
  91 {
  92     int rc = io_submit(ioq->io_ctx, ioq->queue_idx, ioq->queue);
  93     ioq->queue_idx = 0; /* reset */
  94     return rc;
  95 }
  96
  97 int ioq_run_completion(IOQueue *ioq, IOQueueCompletion *completion,
  98                        void *opaque)
  99 {
 100     struct io_event events[ioq->max_reqs];
 101     int nevents, i;
 102
 103     do {
 104         nevents = io_getevents(ioq->io_ctx, 0, ioq->max_reqs, events, NULL);
 105     } while (nevents < 0 && errno == EINTR);
 106     if (nevents < 0) {
 107         return nevents;
 108     }
 109
 110     for (i = 0; i < nevents; i++) {
 111         ssize_t ret = ((uint64_t)events[i].res2 << 32) | events[i].res;
 112
 113         completion(events[i].obj, ret, opaque);
 114         ioq_put_iocb(ioq, events[i].obj);
 115     }
 116     return nevents;
 117 }