debian/patches/fix-aio-poll.patch

   1 aio_poll() must return true if any work is still pending, even if it didn't make progress, so that qemu_aio_wait() doesn't return too early.
   2 The possibility of returning early occasionally lead to a failed assertion in bdrv_drain_all(), when some in-flight request was missed and the function didn't really drain all requests.
   3
   4 In order to make that change, the return value as specified in the function comment must change for blocking = false; fortunately, the return value of blocking = false callers is only used in test cases, so this change shouldn't cause any trouble.
   5
   6 Signed-off-by: Kevin Wolf <kwolf@redhat.com>
   7 ---
   8  aio-posix.c         |    3 ++-
   9  include/block/aio.h |    6 ++----
  10  tests/test-aio.c    |    4 ++--
  11  3 files changed, 6 insertions(+), 7 deletions(-)
  12
  13 Index: new/aio-posix.c
  14 ===================================================================
  15 --- new.orig/aio-posix.c        2013-01-22 07:10:17.000000000 +0100
  16 +++ new/aio-posix.c     2013-01-22 07:10:43.000000000 +0100
  17 @@ -264,5 +264,6 @@
  18          }
  19      }
  20
  21 -    return progress;
  22 +    assert(progress || busy);
  23 +    return true;
  24  }
  25 Index: new/qemu-aio.h
  26 ===================================================================
  27 --- new.orig/qemu-aio.h 2013-01-22 07:10:17.000000000 +0100
  28 +++ new/qemu-aio.h      2013-01-22 07:10:43.000000000 +0100
  29 @@ -177,16 +177,14 @@
  30   * aio as a result of executing I/O completion or bh callbacks.
  31   *
  32   * If there is no pending AIO operation or completion (bottom half),
  33 - * return false.  If there are pending bottom halves, return true.
  34 + * return false.  If there are pending AIO operations of bottom halves,
  35 + * return true.
  36   *
  37   * If there are no pending bottom halves, but there are pending AIO
  38   * operations, it may not be possible to make any progress without
  39   * blocking.  If @blocking is true, this function will wait until one
  40   * or more AIO events have completed, to ensure something has moved
  41   * before returning.
  42 - *
  43 - * If @blocking is false, this function will also return false if the
  44 - * function cannot make any progress without blocking.
  45   */
  46  bool aio_poll(AioContext *ctx, bool blocking);
  47
  48 Index: new/tests/test-aio.c
  49 ===================================================================
  50 --- new.orig/tests/test-aio.c   2013-01-22 07:10:17.000000000 +0100
  51 +++ new/tests/test-aio.c        2013-01-22 07:10:43.000000000 +0100
  52 @@ -315,13 +315,13 @@
  53      event_notifier_set(&data.e);
  54      g_assert(aio_poll(ctx, false));
  55      g_assert_cmpint(data.n, ==, 1);
  56 -    g_assert(!aio_poll(ctx, false));
  57 +    g_assert(aio_poll(ctx, false));
  58      g_assert_cmpint(data.n, ==, 1);
  59
  60      event_notifier_set(&data.e);
  61      g_assert(aio_poll(ctx, false));
  62      g_assert_cmpint(data.n, ==, 2);
  63 -    g_assert(!aio_poll(ctx, false));
  64 +    g_assert(aio_poll(ctx, false));
  65      g_assert_cmpint(data.n, ==, 2);
  66
  67      event_notifier_set(&dummy.e);