On Fri, 08/11 15:28, Fam Zheng wrote:
> On Thu, 08/10 08:58, Eric Blake wrote:
> > On 08/10/2017 03:01 AM, Fam Zheng wrote:
> > > + if (total_size) {
> > > + int64_t zero_size = MIN(BDRV_SECTOR_SIZE, total_size);
> > > + uint8_t *buf;
> >
> > Since BDRV_SECTOR_SIZE is small enough to stack-allocate, you could skip
> > the malloc by doing:
> >
> > uint8_t buf[BDRV_SECTOR_SIZE] = "";
> >
> > > + if (lseek(fd, 0, SEEK_SET) == -1) {
> > > + ret = -errno;
> > > + } else {
> > > + buf = g_malloc0(zero_size);
> > > + ret = qemu_write_full(fd, buf, zero_size);
> >
> > Instead of doing lseek + qemu_write_full, can we just use
> > qemu_pwritev(fd, &iov, 1, 0) with an iov set up to point to the
> > appropriate amount of buf?
>
> Neat, will update.
For stack-allocation yes, but qemu_write_full turns out to be better because of
short write handling. So I'll keep it in v2.
Fam
