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
  18 typedef 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. */
  26 static uint64_t request_id;
  27
  28 static 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;
  44 fail:
  45     if (ret < 0) {
  46         bdrv_unref_child(bs, bs->file);
  47     }
  48     return ret;
  49 }
  50
  51 static void blkreplay_close(BlockDriverState *bs)
  52 {
  53 }
  54
  55 static 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 */
  65 static 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
  73 static 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
  84 static 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
  95 static 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
 106 static 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
 117 static int coroutine_fn blkreplay_co_discard(BlockDriverState *bs,
 118     int64_t sector_num, int nb_sectors)
 119 {
 120     uint64_t reqid = request_id++;
 121     int ret = bdrv_co_discard(bs->file->bs, sector_num, nb_sectors);
 122     block_request_create(reqid, bs, qemu_coroutine_self());
 123     qemu_coroutine_yield();
 124
 125     return ret;
 126 }
 127
 128 static 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
 138 static 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_discard        = blkreplay_co_discard,
 152     .bdrv_co_flush          = blkreplay_co_flush,
 153 };
 154
 155 static void bdrv_blkreplay_init(void)
 156 {
 157     bdrv_register(&bdrv_blkreplay);
 158 }
 159
 160 block_init(bdrv_blkreplay_init);