LXR qemu/block/blkreplay.c

   1/*
   2 * Block protocol for record/replay
   3 *
   4 * Copyright (c) 2010-2016 Institute for System Programming
   5 *                         of the Russian Academy of Sciences.
   6 *
   7 * This work is licensed under the terms of the GNU GPL, version 2 or later.
   8 * See the COPYING file in the top-level directory.
   9 *
  10 */
  11
  12#include "qemu/osdep.h"
  13#include "qemu-common.h"
  14#include "block/block_int.h"
  15#include "sysemu/replay.h"
  16#include "qapi/error.h"
  17
  18typedef struct Request {
  19    Coroutine *co;
  20    QEMUBH *bh;
  21} Request;
  22
  23/* Next request id.
  24   This counter is global, because requests from different
  25   block devices should not get overlapping ids. */
  26static uint64_t request_id;
  27
  28static int blkreplay_open(BlockDriverState *bs, QDict *options, int flags,
  29                          Error **errp)
  30{
  31    Error *local_err = NULL;
  32    int ret;
  33
  34    /* Open the image file */
  35    bs->file = bdrv_open_child(NULL, options, "image",
  36                               bs, &child_file, false, &local_err);
  37    if (local_err) {
  38        ret = -EINVAL;
  39        error_propagate(errp, local_err);
  40        goto fail;
  41    }
  42
  43    ret = 0;
  44fail:
  45    if (ret < 0) {
  46        bdrv_unref_child(bs, bs->file);
  47    }
  48    return ret;
  49}
  50
  51static void blkreplay_close(BlockDriverState *bs)
  52{
  53}
  54
  55static int64_t blkreplay_getlength(BlockDriverState *bs)
  56{
  57    return bdrv_getlength(bs->file->bs);
  58}
  59
  60/* This bh is used for synchronization of return from coroutines.
  61   It continues yielded coroutine which then finishes its execution.
  62   BH is called adjusted to some replay checkpoint, therefore
  63   record and replay will always finish coroutines deterministically.
  64*/
  65static void blkreplay_bh_cb(void *opaque)
  66{
  67    Request *req = opaque;
  68    qemu_coroutine_enter(req->co);
  69    qemu_bh_delete(req->bh);
  70    g_free(req);
  71}
  72
  73static void block_request_create(uint64_t reqid, BlockDriverState *bs,
  74                                 Coroutine *co)
  75{
  76    Request *req = g_new(Request, 1);
  77    *req = (Request) {
  78        .co = co,
  79        .bh = aio_bh_new(bdrv_get_aio_context(bs), blkreplay_bh_cb, req),
  80    };
  81    replay_block_event(req->bh, reqid);
  82}
  83
  84static int coroutine_fn blkreplay_co_preadv(BlockDriverState *bs,
  85    uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
  86{
  87    uint64_t reqid = request_id++;
  88    int ret = bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
  89    block_request_create(reqid, bs, qemu_coroutine_self());
  90    qemu_coroutine_yield();
  91
  92    return ret;
  93}
  94
  95static int coroutine_fn blkreplay_co_pwritev(BlockDriverState *bs,
  96    uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
  97{
  98    uint64_t reqid = request_id++;
  99    int ret = bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
 100    block_request_create(reqid, bs, qemu_coroutine_self());
 101    qemu_coroutine_yield();
 102
 103    return ret;
 104}
 105
 106static int coroutine_fn blkreplay_co_pwrite_zeroes(BlockDriverState *bs,
 107    int64_t offset, int count, BdrvRequestFlags flags)
 108{
 109    uint64_t reqid = request_id++;
 110    int ret = bdrv_co_pwrite_zeroes(bs->file, offset, count, flags);
 111    block_request_create(reqid, bs, qemu_coroutine_self());
 112    qemu_coroutine_yield();
 113
 114    return ret;
 115}
 116
 117static int coroutine_fn blkreplay_co_pdiscard(BlockDriverState *bs,
 118                                              int64_t offset, int count)
 119{
 120    uint64_t reqid = request_id++;
 121    int ret = bdrv_co_pdiscard(bs->file->bs, offset, count);
 122    block_request_create(reqid, bs, qemu_coroutine_self());
 123    qemu_coroutine_yield();
 124
 125    return ret;
 126}
 127
 128static int coroutine_fn blkreplay_co_flush(BlockDriverState *bs)
 129{
 130    uint64_t reqid = request_id++;
 131    int ret = bdrv_co_flush(bs->file->bs);
 132    block_request_create(reqid, bs, qemu_coroutine_self());
 133    qemu_coroutine_yield();
 134
 135    return ret;
 136}
 137
 138static BlockDriver bdrv_blkreplay = {
 139    .format_name            = "blkreplay",
 140    .protocol_name          = "blkreplay",
 141    .instance_size          = 0,
 142
 143    .bdrv_file_open         = blkreplay_open,
 144    .bdrv_close             = blkreplay_close,
 145    .bdrv_getlength         = blkreplay_getlength,
 146
 147    .bdrv_co_preadv         = blkreplay_co_preadv,
 148    .bdrv_co_pwritev        = blkreplay_co_pwritev,
 149
 150    .bdrv_co_pwrite_zeroes  = blkreplay_co_pwrite_zeroes,
 151    .bdrv_co_pdiscard       = blkreplay_co_pdiscard,
 152    .bdrv_co_flush          = blkreplay_co_flush,
 153};
 154
 155static void bdrv_blkreplay_init(void)
 156{
 157    bdrv_register(&bdrv_blkreplay);
 158}
 159
 160block_init(bdrv_blkreplay_init);
 161