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sheepdog: fix dynamic grow for running qcow2 format

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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>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Liu Yuan 2013-12-14 01:29:28 +08:00 committed by Stefan Hajnoczi
parent f8251db121
commit e50d7607f1
1 changed files with 4 additions and 3 deletions
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7
block/sheepdog.c
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@ -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);