On 06/10/2016 10:05 AM, Kevin Wolf wrote: > We don't really want to go through the block layer in order to read from > or write to the vmstate in a qcow2 image. Doing so required a few ugly > hacks like saving and restoring the old image size (because writing to > vmstate offsets would increase the image size) or disabling the "reads > after EOF = zeroes" logic. When calling the right functions directly, > these hacks aren't necessary any more. > > Note that .bdrv_vmstate_load/save() return 0 instead of the number of > bytes in case of success now. > > Signed-off-by: Kevin Wolf <kw...@redhat.com> > --- > block/qcow2.c | 24 ++++-------------------- > 1 file changed, 4 insertions(+), 20 deletions(-) >
> +++ b/block/qcow2.c > @@ -2903,36 +2903,20 @@ static int qcow2_save_vmstate(BlockDriverState *bs, > QEMUIOVector *qiov, > int64_t pos) > { > BDRVQcow2State *s = bs->opaque; > - int64_t total_sectors = bs->total_sectors; > - bool zero_beyond_eof = bs->zero_beyond_eof; > - int ret; > > BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE); > - bs->zero_beyond_eof = false; > - ret = bdrv_pwritev(bs, qcow2_vm_state_offset(s) + pos, qiov); > - bs->zero_beyond_eof = zero_beyond_eof; > - > - /* bdrv_co_do_writev will have increased the total_sectors value to > include > - * the VM state - the VM state is however not an actual part of the block > - * device, therefore, we need to restore the old value. */ > - bs->total_sectors = total_sectors; > - > - return ret; > + return bs->drv->bdrv_co_pwritev(bs, qcow2_vm_state_offset(s) + pos, > + qiov->size, qiov, 0); > } bs->drv->bdrv_co_pwritev() is an optional interface; not all the drivers have it yet. Should you be asserting that it exists, and/or returning an error if it does not? > > static int qcow2_load_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, > int64_t pos) > { > BDRVQcow2State *s = bs->opaque; > - bool zero_beyond_eof = bs->zero_beyond_eof; > - int ret; > > BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_LOAD); > - bs->zero_beyond_eof = false; > - ret = bdrv_preadv(bs, qcow2_vm_state_offset(s) + pos, qiov); > - bs->zero_beyond_eof = zero_beyond_eof; > - > - return ret; > + return bs->drv->bdrv_co_preadv(bs, qcow2_vm_state_offset(s) + pos, > + qiov->size, qiov, 0); Ditto. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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