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 coroutine_fn GRAPH_RDLOCK
  44 blkreplay_co_getlength(BlockDriverState *bs)
  45 {
  46     return bdrv_co_getlength(bs->file->bs);
  47 }
  48
  49 /* This bh is used for synchronization of return from coroutines.
  50    It continues yielded coroutine which then finishes its execution.
  51    BH is called adjusted to some replay checkpoint, therefore
  52    record and replay will always finish coroutines deterministically.
  53 */
  54 static void blkreplay_bh_cb(void *opaque)
  55 {
  56     Request *req = opaque;
  57     aio_co_wake(req->co);
  58     qemu_bh_delete(req->bh);
  59     g_free(req);
  60 }
  61
  62 static void block_request_create(uint64_t reqid, BlockDriverState *bs,
  63                                  Coroutine *co)
  64 {
  65     Request *req = g_new(Request, 1);
  66     *req = (Request) {
  67         .co = co,
  68         .bh = aio_bh_new(bdrv_get_aio_context(bs), blkreplay_bh_cb, req),
  69     };
  70     replay_block_event(req->bh, reqid);
  71 }
  72
  73 static int coroutine_fn GRAPH_RDLOCK
  74 blkreplay_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
  75                     QEMUIOVector *qiov, BdrvRequestFlags flags)
  76 {
  77     uint64_t reqid = blkreplay_next_id();
  78     int ret = bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
  79     block_request_create(reqid, bs, qemu_coroutine_self());
  80     qemu_coroutine_yield();
  81
  82     return ret;
  83 }
  84
  85 static int coroutine_fn GRAPH_RDLOCK
  86 blkreplay_co_pwritev(BlockDriverState *bs, int64_t offset, int64_t bytes,
  87                      QEMUIOVector *qiov, BdrvRequestFlags 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 GRAPH_RDLOCK
  98 blkreplay_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset, int64_t bytes,
  99                            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 GRAPH_RDLOCK
 110 blkreplay_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t 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 GRAPH_RDLOCK 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     BlockDriverState *file_bs;
 134
 135     bdrv_graph_rdlock_main_loop();
 136     file_bs = bs->file->bs;
 137     bdrv_graph_rdunlock_main_loop();
 138
 139     return bdrv_snapshot_goto(file_bs, snapshot_id, NULL);
 140 }
 141
 142 static BlockDriver bdrv_blkreplay = {
 143     .format_name            = "blkreplay",
 144     .instance_size          = 0,
 145     .is_filter              = true,
 146
 147     .bdrv_open              = blkreplay_open,
 148     .bdrv_child_perm        = bdrv_default_perms,
 149     .bdrv_co_getlength      = blkreplay_co_getlength,
 150
 151     .bdrv_co_preadv         = blkreplay_co_preadv,
 152     .bdrv_co_pwritev        = blkreplay_co_pwritev,
 153
 154     .bdrv_co_pwrite_zeroes  = blkreplay_co_pwrite_zeroes,
 155     .bdrv_co_pdiscard       = blkreplay_co_pdiscard,
 156     .bdrv_co_flush          = blkreplay_co_flush,
 157
 158     .bdrv_snapshot_goto     = blkreplay_snapshot_goto,
 159 };
 160
 161 static void bdrv_blkreplay_init(void)
 162 {
 163     bdrv_register(&bdrv_blkreplay);
 164 }
 165
 166 block_init(bdrv_blkreplay_init);