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",
  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;
  42 fail:
  43     return ret;
  44 }
  45
  46 static 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 */
  56 static 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
  64 static 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
  75 static 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
  86 static 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
  97 static 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
 108 static 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
 119 static 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
 129 static 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
 135 static 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
 153 static void bdrv_blkreplay_init(void)
 154 {
 155     bdrv_register(&bdrv_blkreplay);
 156 }
 157
 158 block_init(bdrv_blkreplay_init);