• Stefan Hajnoczi's avatar
    stream: complete early if end of backing file is reached · 571cd9dc
    Stefan Hajnoczi authored
    It is possible to create an image that is larger than its backing file.
    Reading beyond the end of the backing file produces zeroes if no writes
    have been made to those sectors in the image file.
    
    This patch finishes streaming early when the end of the backing file is
    reached.  Without this patch the block job hangs and continually tries
    to stream the first sectors beyond the end of the backing file.
    
    To reproduce the hung block job bug:
    
      $ qemu-img create -f qcow2 backing.qcow2 128M
      $ qemu-img create -f qcow2 -o backing_file=backing.qcow2 image.qcow2 6G
      $ qemu -drive if=virtio,cache=none,file=image.qcow2
      (qemu) block_stream virtio0
      (qemu) info block-jobs
    
    The qemu-iotests 030 streaming test still passes.
    Signed-off-by: default avatarStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
    Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
    Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
    571cd9dc
stream.c 5.84 KB