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
  18 typedef struct Request {
  19     Coroutine *co;
  20     QEMUBH *bh;
  21 } Request;
  22
  23 static 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", bs, &child_of_bds,
  31                                BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
  32                                false, &local_err);
  33     if (local_err) {
  34         ret = -EINVAL;
  35         error_propagate(errp, local_err);
  36         goto fail;
  37     }
  38
  39     bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;
  40     bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED;
  41
  42     ret = 0;
  43 fail:
  44     return ret;
  45 }
  46
  47 static int64_t blkreplay_getlength(BlockDriverState *bs)
  48 {
  49     return bdrv_getlength(bs->file->bs);
  50 }
  51
  52 /* This bh is used for synchronization of return from coroutines.
  53    It continues yielded coroutine which then finishes its execution.
  54    BH is called adjusted to some replay checkpoint, therefore
  55    record and replay will always finish coroutines deterministically.
  56 */
  57 static void blkreplay_bh_cb(void *opaque)
  58 {
  59     Request *req = opaque;
  60     aio_co_wake(req->co);
  61     qemu_bh_delete(req->bh);
  62     g_free(req);
  63 }
  64
  65 static void block_request_create(uint64_t reqid, BlockDriverState *bs,
  66                                  Coroutine *co)
  67 {
  68     Request *req = g_new(Request, 1);
  69     *req = (Request) {
  70         .co = co,
  71         .bh = aio_bh_new(bdrv_get_aio_context(bs), blkreplay_bh_cb, req),
  72     };
  73     replay_block_event(req->bh, reqid);
  74 }
  75
  76 static int coroutine_fn blkreplay_co_preadv(BlockDriverState *bs,
  77     uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
  78 {
  79     uint64_t reqid = blkreplay_next_id();
  80     int ret = bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
  81     block_request_create(reqid, bs, qemu_coroutine_self());
  82     qemu_coroutine_yield();
  83
  84     return ret;
  85 }
  86
  87 static int coroutine_fn blkreplay_co_pwritev(BlockDriverState *bs,
  88     uint64_t offset, uint64_t bytes, QEMUIOVector *qiov, int flags)
  89 {
  90     uint64_t reqid = blkreplay_next_id();
  91     int ret = bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
  92     block_request_create(reqid, bs, qemu_coroutine_self());
  93     qemu_coroutine_yield();
  94
  95     return ret;
  96 }
  97
  98 static int coroutine_fn blkreplay_co_pwrite_zeroes(BlockDriverState *bs,
  99     int64_t offset, int bytes, BdrvRequestFlags flags)
 100 {
 101     uint64_t reqid = blkreplay_next_id();
 102     int ret = bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
 103     block_request_create(reqid, bs, qemu_coroutine_self());
 104     qemu_coroutine_yield();
 105
 106     return ret;
 107 }
 108
 109 static int coroutine_fn blkreplay_co_pdiscard(BlockDriverState *bs,
 110                                               int64_t offset, int bytes)
 111 {
 112     uint64_t reqid = blkreplay_next_id();
 113     int ret = bdrv_co_pdiscard(bs->file, offset, bytes);
 114     block_request_create(reqid, bs, qemu_coroutine_self());
 115     qemu_coroutine_yield();
 116
 117     return ret;
 118 }
 119
 120 static int coroutine_fn blkreplay_co_flush(BlockDriverState *bs)
 121 {
 122     uint64_t reqid = blkreplay_next_id();
 123     int ret = bdrv_co_flush(bs->file->bs);
 124     block_request_create(reqid, bs, qemu_coroutine_self());
 125     qemu_coroutine_yield();
 126
 127     return ret;
 128 }
 129
 130 static int blkreplay_snapshot_goto(BlockDriverState *bs,
 131                                    const char *snapshot_id)
 132 {
 133     return bdrv_snapshot_goto(bs->file->bs, snapshot_id, NULL);
 134 }
 135
 136 static BlockDriver bdrv_blkreplay = {
 137     .format_name            = "blkreplay",
 138     .instance_size          = 0,
 139     .is_filter              = true,
 140
 141     .bdrv_open              = blkreplay_open,
 142     .bdrv_child_perm        = bdrv_default_perms,
 143     .bdrv_getlength         = blkreplay_getlength,
 144
 145     .bdrv_co_preadv         = blkreplay_co_preadv,
 146     .bdrv_co_pwritev        = blkreplay_co_pwritev,
 147
 148     .bdrv_co_pwrite_zeroes  = blkreplay_co_pwrite_zeroes,
 149     .bdrv_co_pdiscard       = blkreplay_co_pdiscard,
 150     .bdrv_co_flush          = blkreplay_co_flush,
 151
 152     .bdrv_snapshot_goto     = blkreplay_snapshot_goto,
 153 };
 154
 155 static void bdrv_blkreplay_init(void)
 156 {
 157     bdrv_register(&bdrv_blkreplay);
 158 }
 159
 160 block_init(bdrv_blkreplay_init);