| Message ID | 1401970536-18019-4-git-send-email-armbru@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Thu, 06/05 14:15, Markus Armbruster wrote: > The block layer fails such reads and writes just fine. However, they > then get treated like valid operations that fail: the error action > gets executed. Unwanted; reporting the error to the guest is the only > sensible action. > > Reject them before passing them to the block layer. This bypasses the > error action and I/O accounting. > > Signed-off-by: Markus Armbruster <armbru@redhat.com> > --- > hw/block/virtio-blk.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c > index 2c68d0d..0b38049 100644 > --- a/hw/block/virtio-blk.c > +++ b/hw/block/virtio-blk.c > @@ -284,12 +284,19 @@ static void virtio_blk_handle_flush(VirtIOBlockReq *req, MultiReqBuffer *mrb) > static bool virtio_blk_sect_range_ok(VirtIOBlock *dev, > uint64_t sector, size_t size) > { > + uint64_t nb_sectors = size >> BDRV_SECTOR_BITS; > + uint64_t total_sectors; > + > if (sector & dev->sector_mask) { > return false; > } > if (size % dev->conf->logical_block_size) { > return false; > } > + bdrv_get_geometry(dev->bs, &total_sectors); > + if (sector > total_sectors || nb_sectors > total_sectors - sector) { > + return false; > + } > return true; > } > > -- > 1.9.3 > > Reviewed-by: Fam Zheng <famz@redhat.com>
On Thu, Jun 05, 2014 at 02:15:36PM +0200, Markus Armbruster wrote: > + if (sector > total_sectors || nb_sectors > total_sectors - sector) { > + return false; > + } if (sector >= total_sectors || ...) {
Stefan Hajnoczi <stefanha@redhat.com> writes: > On Thu, Jun 05, 2014 at 02:15:36PM +0200, Markus Armbruster wrote: >> + if (sector > total_sectors || nb_sectors > total_sectors - sector) { >> + return false; >> + } > > if (sector >= total_sectors || ...) { I suspect reading bdrv_check_byte_request() put the '>' in my brain: if ((offset > len) || (len - offset < size)) return -EIO; Don't we need offset >= len here?
Markus Armbruster <armbru@redhat.com> writes: > Stefan Hajnoczi <stefanha@redhat.com> writes: > >> On Thu, Jun 05, 2014 at 02:15:36PM +0200, Markus Armbruster wrote: >>> + if (sector > total_sectors || nb_sectors > total_sectors - sector) { >>> + return false; >>> + } >> >> if (sector >= total_sectors || ...) { > > I suspect reading bdrv_check_byte_request() put the '>' in my brain: > > if ((offset > len) || (len - offset < size)) > return -EIO; > > Don't we need offset >= len here? Just remembered: we don't, because we allow I/O at offset len provided size is zero. Same reasoning applies to my patch.
On Mon, Jun 23, 2014 at 02:57:36PM +0200, Markus Armbruster wrote: > Markus Armbruster <armbru@redhat.com> writes: > > > Stefan Hajnoczi <stefanha@redhat.com> writes: > > > >> On Thu, Jun 05, 2014 at 02:15:36PM +0200, Markus Armbruster wrote: > >>> + if (sector > total_sectors || nb_sectors > total_sectors - sector) { > >>> + return false; > >>> + } > >> > >> if (sector >= total_sectors || ...) { > > > > I suspect reading bdrv_check_byte_request() put the '>' in my brain: > > > > if ((offset > len) || (len - offset < size)) > > return -EIO; > > > > Don't we need offset >= len here? > > Just remembered: we don't, because we allow I/O at offset len provided > size is zero. > > Same reasoning applies to my patch. Okay. I didn't remember the offset=eof length=0 thing. Stefan
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 2c68d0d..0b38049 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -284,12 +284,19 @@ static void virtio_blk_handle_flush(VirtIOBlockReq *req, MultiReqBuffer *mrb) static bool virtio_blk_sect_range_ok(VirtIOBlock *dev, uint64_t sector, size_t size) { + uint64_t nb_sectors = size >> BDRV_SECTOR_BITS; + uint64_t total_sectors; + if (sector & dev->sector_mask) { return false; } if (size % dev->conf->logical_block_size) { return false; } + bdrv_get_geometry(dev->bs, &total_sectors); + if (sector > total_sectors || nb_sectors > total_sectors - sector) { + return false; + } return true; }
The block layer fails such reads and writes just fine. However, they then get treated like valid operations that fail: the error action gets executed. Unwanted; reporting the error to the guest is the only sensible action. Reject them before passing them to the block layer. This bypasses the error action and I/O accounting. Signed-off-by: Markus Armbruster <armbru@redhat.com> --- hw/block/virtio-blk.c | 7 +++++++ 1 file changed, 7 insertions(+)