| Message ID | 1386955768-31830-1-git-send-email-namei.unix@gmail.com |
|---|---|
| State | New |
| Headers | show |
On Sat, Dec 14, 2013 at 01:29:28AM +0800, Liu Yuan wrote: > When running qcow2 over sheepdog, we might meet following problem > > qemu-system-x86_64: shrinking is not supported > > And cause IO errors to Guest. This is because we abuse bs->total_sectors, which > is manipulated by generic block layer and race with sheepdog code. > > We should directly check if offset > vdi_size to dynamically enlarge the volume > instead of 'offset > bs->total_sectors', which will cause problem when following > case happens: > > vdi_size > offset > bs->total_sectors > > # then trigger sd_truncate() to shrink the volume wrongly. > > Cc: qemu-devel@nongnu.org > Cc: Kevin Wolf <kwolf@redhat.com> > Cc: Stefan Hajnoczi <stefanha@redhat.com> > Reported-by: Hadrien KOHL <hadrien.kohl@gmail.com> > Signed-off-by: Liu Yuan <namei.unix@gmail.com> > --- > block/sheepdog.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) block.c already updates bs->total_sectors if bs->growable so this patch is safe. Thanks, applied to my block tree: https://github.com/stefanha/qemu/commits/block Stefan
diff --git a/block/sheepdog.c b/block/sheepdog.c index d1c812d..ba451a9 100644 --- a/block/sheepdog.c +++ b/block/sheepdog.c @@ -2048,13 +2048,14 @@ static coroutine_fn int sd_co_writev(BlockDriverState *bs, int64_t sector_num, { SheepdogAIOCB *acb; int ret; + int64_t offset = (sector_num + nb_sectors) * BDRV_SECTOR_SIZE; + BDRVSheepdogState *s = bs->opaque; - if (bs->growable && sector_num + nb_sectors > bs->total_sectors) { - ret = sd_truncate(bs, (sector_num + nb_sectors) * BDRV_SECTOR_SIZE); + if (bs->growable && offset > s->inode.vdi_size) { + ret = sd_truncate(bs, offset); if (ret < 0) { return ret; } - bs->total_sectors = sector_num + nb_sectors; } acb = sd_aio_setup(bs, qiov, sector_num, nb_sectors);
When running qcow2 over sheepdog, we might meet following problem qemu-system-x86_64: shrinking is not supported And cause IO errors to Guest. This is because we abuse bs->total_sectors, which is manipulated by generic block layer and race with sheepdog code. We should directly check if offset > vdi_size to dynamically enlarge the volume instead of 'offset > bs->total_sectors', which will cause problem when following case happens: vdi_size > offset > bs->total_sectors # then trigger sd_truncate() to shrink the volume wrongly. Cc: qemu-devel@nongnu.org Cc: Kevin Wolf <kwolf@redhat.com> Cc: Stefan Hajnoczi <stefanha@redhat.com> Reported-by: Hadrien KOHL <hadrien.kohl@gmail.com> Signed-off-by: Liu Yuan <namei.unix@gmail.com> --- block/sheepdog.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)