qcow2: Fix preallocation bdrv_pwrite to wrong file
commit93e32b3e2012a668e4da1c2566d2935c24060435
authorKevin Wolf <kwolf@redhat.com>
Mon, 15 Apr 2019 15:54:50 +0000 (15 17:54 +0200)
committerKevin Wolf <kwolf@redhat.com>
Tue, 16 Apr 2019 14:23:24 +0000 (16 16:23 +0200)
treec86b9fbe0dcffef530814421239a708776f8400d
parenta9b305ba291fb74f7ff732b3d7b8f4c812431ddf
qcow2: Fix preallocation bdrv_pwrite to wrong file

With an external data file, preallocate_co() must write the final byte
to the external data file, not to the qcow2 image file.

This is harmless for preallocation of newly created images (only the
qcow2 file size is increased to the virtual disk size while it should be
much smaller), but with preallocated resize, it could in theory cause
visible corruption if the metadata of the image is larger than the data
(e.g. lots of bitmaps).

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
block/qcow2.c