Peter Maydell <peter.mayd...@linaro.org> 于2023年6月3日周六 00:52写道：
>
> On Mon, 15 May 2023 at 17:06, Stefan Hajnoczi <stefa...@redhat.com> wrote:
> >
> > From: Sam Li <faithilike...@gmail.com>
> >
> > A zone append command is a write operation that specifies the first
> > logical block of a zone as the write position. When writing to a zoned
> > block device using zone append, the byte offset of the call may point at
> > any position within the zone to which the data is being appended. Upon
> > completion the device will respond with the position where the data has
> > been written in the zone.
> >
> > Signed-off-by: Sam Li <faithilike...@gmail.com>
> > Reviewed-by: Dmitry Fomichev <dmitry.fomic...@wdc.com>
> > Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
> > Message-id: 20230508051510.177850-3-faithilike...@gmail.com
> > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
>
> Hi; Coverity flagged up a possible bug here (CID 1512459):
>
> > @@ -2453,8 +2454,12 @@ static int coroutine_fn raw_co_prw(BlockDriverState
> > *bs, uint64_t offset,
> > if (fd_open(bs) < 0)
> > return -EIO;
> > #if defined(CONFIG_BLKZONED)
> > - if (type & QEMU_AIO_WRITE && bs->wps) {
> > + if ((type & (QEMU_AIO_WRITE | QEMU_AIO_ZONE_APPEND)) && bs->wps) {
>
> Here we check for bs->wps being NULL, which implies that it might be NULL...
>
> > qemu_co_mutex_lock(&bs->wps->colock);
> > + if (type & QEMU_AIO_ZONE_APPEND && bs->bl.zone_size) {
> > + int index = offset / bs->bl.zone_size;
> > + offset = bs->wps->wp[index];
> > + }
> > }
> > #endif
> >
> > @@ -2502,9 +2507,13 @@ out:
> > {
> > BlockZoneWps *wps = bs->wps;
> > if (ret == 0) {
> > - if (type & QEMU_AIO_WRITE && wps && bs->bl.zone_size) {
> > + if ((type & (QEMU_AIO_WRITE | QEMU_AIO_ZONE_APPEND))
> > + && wps && bs->bl.zone_size) {
> > uint64_t *wp = &wps->wp[offset / bs->bl.zone_size];
> > if (!BDRV_ZT_IS_CONV(*wp)) {
> > + if (type & QEMU_AIO_ZONE_APPEND) {
> > + *s->offset = *wp;
> > + }
> > /* Advance the wp if needed */
> > if (offset + bytes > *wp) {
> > *wp = offset + bytes;
> > @@ -2512,12 +2521,12 @@ out:
> > }
> > }
> > } else {
> > - if (type & QEMU_AIO_WRITE) {
> > + if (type & (QEMU_AIO_WRITE | QEMU_AIO_ZONE_APPEND)) {
>
> ...but here we do not, even though update_zones_wp() can
> dereference bs->wps in some code paths.
>
> Should we be checking for NULL here before calling, or
> should update_zones_wp() handle a NULL bs->wps, or something else?
Hi Peter,
Thanks for spotting this. You are right that bs->wps is not checked in
this code path. I think the get_zones_wp() should handle a NULL
bs->wps which is the function calling wps directly.
Would you like to submit a patch for this? Or I can do it if you are
not available.
Thanks,
Sam
>
> > update_zones_wp(bs, s->fd, 0, 1);
> > }
> > }
> >
> > - if (type & QEMU_AIO_WRITE && wps) {
> > + if ((type & (QEMU_AIO_WRITE | QEMU_AIO_ZONE_APPEND)) && wps) {
> > qemu_co_mutex_unlock(&wps->colock);
> > }
> > }
>
> thanks
> -- PMM
