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/module.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
  23static int blkreplay_open(BlockDriverState *bs, QDict *options, int flags,
  24                          Error **errp)
  25{
  26    Error *local_err = NULL;
  27    int ret;
  28
  29    /* Open the image file */
  30    bs->file = bdrv_open_child(NULL, options, "image",
  31                               bs, &child_file, false, &local_err);
  32    if (local_err) {
  33        ret = -EINVAL;
  34        error_propagate(errp, local_err);
  35        goto fail;
  36    }
  37
  38    bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;
  39    bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED;
  40
  41    ret = 0;
  42fail:
  43    return ret;
  44}
  45
  46static int64_t blkreplay_getlength(BlockDriverState *bs)
  47{
  48    return bdrv_getlength(bs->file->bs);
  49}
  50
  51/* This bh is used for synchronization of return from coroutines.
  52   It continues yielded coroutine which then finishes its execution.
  53   BH is called adjusted to some replay checkpoint, therefore
  54   record and replay will always finish coroutines deterministically.
  55*/
  56static void blkreplay_bh_cb(void *opaque)
  57{
  58    Request *req = opaque;
  59    aio_co_wake(req->co);
  60    qemu_bh_delete(req->bh);
  61    g_free(req);
  62}
  63
  64static void block_request_create(uint64_t reqid, BlockDriverState *bs,
  65                                 Coroutine *co)
  66{
  67    Request *req = g_new(Request, 1);
  68    *req = (Request) {
  69        .co = co,
  70        .bh = aio_bh_new(bdrv_get_aio_context(bs), blkreplay_bh_cb, req),
  71    };
  72    replay_block_event(req->bh, reqid);
  73}
  74
  75static int coroutine_fn blkreplay_co_preadv(BlockDriverState *bs,
  76    uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
  77{
  78    uint64_t reqid = blkreplay_next_id();
  79    int ret = bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
  80    block_request_create(reqid, bs, qemu_coroutine_self());
  81    qemu_coroutine_yield();
  82
  83    return ret;
  84}
  85
  86static int coroutine_fn blkreplay_co_pwritev(BlockDriverState *bs,
  87    uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
  88{
  89    uint64_t reqid = blkreplay_next_id();
  90    int ret = bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
  91    block_request_create(reqid, bs, qemu_coroutine_self());
  92    qemu_coroutine_yield();
  93
  94    return ret;
  95}
  96
  97static int coroutine_fn blkreplay_co_pwrite_zeroes(BlockDriverState *bs,
  98    int64_t offset, int bytes, BdrvRequestFlags flags)
  99{
 100    uint64_t reqid = blkreplay_next_id();
 101    int ret = bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
 102    block_request_create(reqid, bs, qemu_coroutine_self());
 103    qemu_coroutine_yield();
 104
 105    return ret;
 106}
 107
 108static int coroutine_fn blkreplay_co_pdiscard(BlockDriverState *bs,
 109                                              int64_t offset, int bytes)
 110{
 111    uint64_t reqid = blkreplay_next_id();
 112    int ret = bdrv_co_pdiscard(bs->file, offset, bytes);
 113    block_request_create(reqid, bs, qemu_coroutine_self());
 114    qemu_coroutine_yield();
 115
 116    return ret;
 117}
 118
 119static int coroutine_fn blkreplay_co_flush(BlockDriverState *bs)
 120{
 121    uint64_t reqid = blkreplay_next_id();
 122    int ret = bdrv_co_flush(bs->file->bs);
 123    block_request_create(reqid, bs, qemu_coroutine_self());
 124    qemu_coroutine_yield();
 125
 126    return ret;
 127}
 128
 129static int blkreplay_snapshot_goto(BlockDriverState *bs,
 130                                   const char *snapshot_id)
 131{
 132    return bdrv_snapshot_goto(bs->file->bs, snapshot_id, NULL);
 133}
 134
 135static BlockDriver bdrv_blkreplay = {
 136    .format_name            = "blkreplay",
 137    .instance_size          = 0,
 138
 139    .bdrv_open              = blkreplay_open,
 140    .bdrv_child_perm        = bdrv_filter_default_perms,
 141    .bdrv_getlength         = blkreplay_getlength,
 142
 143    .bdrv_co_preadv         = blkreplay_co_preadv,
 144    .bdrv_co_pwritev        = blkreplay_co_pwritev,
 145
 146    .bdrv_co_pwrite_zeroes  = blkreplay_co_pwrite_zeroes,
 147    .bdrv_co_pdiscard       = blkreplay_co_pdiscard,
 148    .bdrv_co_flush          = blkreplay_co_flush,
 149
 150    .bdrv_snapshot_goto     = blkreplay_snapshot_goto,
 151};
 152
 153static void bdrv_blkreplay_init(void)
 154{
 155    bdrv_register(&bdrv_blkreplay);
 156}
 157
 158block_init(bdrv_blkreplay_init);
 159