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-io.h"
  15 #include "block/block_int.h"
  16 #include "sysemu/replay.h"
  17 #include "qapi/error.h"
  18
  19 typedef struct Request {
  20     Coroutine *co;
  21     QEMUBH *bh;
  22 } Request;
  23
  24 static int blkreplay_open(BlockDriverState *bs, QDict *options, int flags,
  25                           Error **errp)
  26 {
  27     int ret;
  28
  29     /* Open the image file */
  30     ret = bdrv_open_file_child(NULL, options, "image", bs, errp);
  31     if (ret < 0) {
  32         goto fail;
  33     }
  34
  35     bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;
  36     bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED;
  37
  38     ret = 0;
  39 fail:
  40     return ret;
  41 }
  42
  43 static int64_t blkreplay_getlength(BlockDriverState *bs)
  44 {
  45     return bdrv_getlength(bs->file->bs);
  46 }
  47
  48 /* This bh is used for synchronization of return from coroutines.
  49    It continues yielded coroutine which then finishes its execution.
  50    BH is called adjusted to some replay checkpoint, therefore
  51    record and replay will always finish coroutines deterministically.
  52 */
  53 static void blkreplay_bh_cb(void *opaque)
  54 {
  55     Request *req = opaque;
  56     aio_co_wake(req->co);
  57     qemu_bh_delete(req->bh);
  58     g_free(req);
  59 }
  60
  61 static void block_request_create(uint64_t reqid, BlockDriverState *bs,
  62                                  Coroutine *co)
  63 {
  64     Request *req = g_new(Request, 1);
  65     *req = (Request) {
  66         .co = co,
  67         .bh = aio_bh_new(bdrv_get_aio_context(bs), blkreplay_bh_cb, req),
  68     };
  69     replay_block_event(req->bh, reqid);
  70 }
  71
  72 static int coroutine_fn blkreplay_co_preadv(BlockDriverState *bs,
  73     int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags)
  74 {
  75     uint64_t reqid = blkreplay_next_id();
  76     int ret = bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
  77     block_request_create(reqid, bs, qemu_coroutine_self());
  78     qemu_coroutine_yield();
  79
  80     return ret;
  81 }
  82
  83 static int coroutine_fn blkreplay_co_pwritev(BlockDriverState *bs,
  84     int64_t offset, int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags)
  85 {
  86     uint64_t reqid = blkreplay_next_id();
  87     int ret = bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
  88     block_request_create(reqid, bs, qemu_coroutine_self());
  89     qemu_coroutine_yield();
  90
  91     return ret;
  92 }
  93
  94 static int coroutine_fn blkreplay_co_pwrite_zeroes(BlockDriverState *bs,
  95     int64_t offset, int64_t bytes, BdrvRequestFlags flags)
  96 {
  97     uint64_t reqid = blkreplay_next_id();
  98     int ret = bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
  99     block_request_create(reqid, bs, qemu_coroutine_self());
 100     qemu_coroutine_yield();
 101
 102     return ret;
 103 }
 104
 105 static int coroutine_fn blkreplay_co_pdiscard(BlockDriverState *bs,
 106                                               int64_t offset, int64_t bytes)
 107 {
 108     uint64_t reqid = blkreplay_next_id();
 109     int ret = bdrv_co_pdiscard(bs->file, offset, bytes);
 110     block_request_create(reqid, bs, qemu_coroutine_self());
 111     qemu_coroutine_yield();
 112
 113     return ret;
 114 }
 115
 116 static int coroutine_fn blkreplay_co_flush(BlockDriverState *bs)
 117 {
 118     uint64_t reqid = blkreplay_next_id();
 119     int ret = bdrv_co_flush(bs->file->bs);
 120     block_request_create(reqid, bs, qemu_coroutine_self());
 121     qemu_coroutine_yield();
 122
 123     return ret;
 124 }
 125
 126 static int blkreplay_snapshot_goto(BlockDriverState *bs,
 127                                    const char *snapshot_id)
 128 {
 129     return bdrv_snapshot_goto(bs->file->bs, snapshot_id, NULL);
 130 }
 131
 132 static BlockDriver bdrv_blkreplay = {
 133     .format_name            = "blkreplay",
 134     .instance_size          = 0,
 135     .is_filter              = true,
 136
 137     .bdrv_open              = blkreplay_open,
 138     .bdrv_child_perm        = bdrv_default_perms,
 139     .bdrv_getlength         = blkreplay_getlength,
 140
 141     .bdrv_co_preadv         = blkreplay_co_preadv,
 142     .bdrv_co_pwritev        = blkreplay_co_pwritev,
 143
 144     .bdrv_co_pwrite_zeroes  = blkreplay_co_pwrite_zeroes,
 145     .bdrv_co_pdiscard       = blkreplay_co_pdiscard,
 146     .bdrv_co_flush          = blkreplay_co_flush,
 147
 148     .bdrv_snapshot_goto     = blkreplay_snapshot_goto,
 149 };
 150
 151 static void bdrv_blkreplay_init(void)
 152 {
 153     bdrv_register(&bdrv_blkreplay);
 154 }
 155
 156 block_init(bdrv_blkreplay_init);