@@ -121,8 +121,42 @@ static int coroutine_fn cor_co_preadv_part(BlockDriverState *bs,
size_t qiov_offset,
int flags)
{
- return bdrv_co_preadv_part(bs->file, offset, bytes, qiov, qiov_offset,
- flags | BDRV_REQ_COPY_ON_READ);
+ int64_t n = 0;
+ int64_t size = offset + bytes;
+ int local_flags;
+ int ret;
+ BDRVStateCOR *state = bs->opaque;
+
+ if (!state->base_bs) {
+ return bdrv_co_preadv_part(bs->file, offset, bytes, qiov, qiov_offset,
+ flags | BDRV_REQ_COPY_ON_READ);
+ }
+
+ while (offset < size) {
+ local_flags = flags;
+
+ /* In case of failure, try to copy-on-read anyway */
+ ret = bdrv_is_allocated(bs->file->bs, offset, bytes, &n);
+ if (!ret) {
+ ret = bdrv_is_allocated_above(bdrv_cow_bs(bs->file->bs),
+ state->base_bs, false, offset, n, &n);
+ if (ret > 0) {
+ local_flags |= BDRV_REQ_COPY_ON_READ;
+ }
+ }
+
+ ret = bdrv_co_preadv_part(bs->file, offset, n, qiov, qiov_offset,
+ local_flags);
+ if (ret < 0) {
+ return ret;
+ }
+
+ offset += n;
+ qiov_offset += n;
+ bytes -= n;
+ }
+
+ return 0;
}
Limit the guest's COR operations by the base node in the backing chain when the base node name is given. It will be useful for a block stream job when the COR-filter is applied. Signed-off-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com> --- block/copy-on-read.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-)