When calling bdrv_getlength() in handle_aiocb_write_zeroes(), the
function creates a new coroutine and then waits that it finishes using
AIO_WAIT_WHILE.
The problem is that this function could also run in a worker thread,
that has a different AioContext from main loop and iothreads, therefore
in AIO_WAIT_WHILE we will have in_aio_context_home_thread(ctx) == false
and therefore
assert(qemu_get_current_aio_context() == qemu_get_aio_context());
in the else branch will fail, crashing QEMU.
Aside from that, bdrv_getlength() is wrong also conceptually, because
it reads the BDS graph from another thread and is not protected by
any lock.
Replace it with raw_co_getlength, that doesn't create a coroutine and
doesn't read the BDS graph.
Reported-by: Ninad Palsule <ninad@linux.vnet.ibm.com>
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Message-Id: <
20230209154522.
1164401-1-eesposit@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
#ifdef CONFIG_FALLOCATE
/* Last resort: we are trying to extend the file with zeroed data. This
* can be done via fallocate(fd, 0) */
- len = bdrv_getlength(aiocb->bs);
+ len = raw_co_getlength(aiocb->bs);
if (s->has_fallocate && len >= 0 && aiocb->aio_offset >= len) {
int ret = do_fallocate(s->fd, 0, aiocb->aio_offset, aiocb->aio_nbytes);
if (ret == 0 || ret != -ENOTSUP) {