Re: [Qemu-devel] [PATCH] avoid core reading with bdrv_read (qemu-io)

[Kevin Wolf <kwolf@redhat.com>]

Am 19.07.2011 09:33, schrieb Frediano Ziglio:
> This patch apply to kevin coroutine-block branch and avoid code. It
> fix "qcow: Use coroutines" patch. Test case:
> 
> $ ./qemu-img create -f qcow aaa.img 1G
> Formatting 'aaa.img', fmt=qcow size=1073741824 encryption=off
> $ ./qemu-io aaa.img
> qemu-io> read 1024 1024
> Segmentation fault
> 
> Signed-off-by: Frediano Ziglio <freddy77@gmail.com>

Thanks for the report. I'll update the patch, but in a slightly
different way that matches the old code better:

diff --git a/block/qcow.c b/block/qcow.c
index 6f7973c..6447c2a 100644
--- a/block/qcow.c
+++ b/block/qcow.c
@@ -573,7 +573,6 @@ static int qcow_aio_read_cb(void *opaque)

     if (acb->nb_sectors == 0) {
         /* request completed */
-        qemu_iovec_from_buffer(acb->qiov, acb->orig_buf, acb->qiov->size);
         return 0;
     }

@@ -647,6 +646,7 @@ static int qcow_co_readv(BlockDriverState *bs,
int64_t sector_num,
     qemu_co_mutex_unlock(&s->lock);

     if (acb->qiov->niov > 1) {
+        qemu_iovec_from_buffer(acb->qiov, acb->orig_buf, acb->qiov->size);
         qemu_vfree(acb->orig_buf);
     }
     qemu_aio_release(acb);