On 11/30/2017 04:12 PM, Eric Blake wrote:
BDRVParallelsState *s = bs->opaque;
- int64_t offset;
+ int count;
+ assert(QEMU_IS_ALIGNED(offset | bytes, BDRV_SECTOR_SIZE));
qemu_co_mutex_lock(&s->lock);
- offset = block_status(s, sector_num, nb_sectors, pnum);
+ offset = block_status(s, offset >> BDRV_SECTOR_BITS,
+ bytes >> BDRV_SECTOR_BITS, &count);
qemu_co_mutex_unlock(&s->lock);
if (offset < 0) {
pnum=count*BDRV_SECTOR_SIZE and map=0 setting missed here.
return 0;
}
Setting *map is only required when return value includes
BDRV_BLOCK_OFFSET_VALID, so that one was not necessary. But you do
raise an interesting point about a pre-existing bug with pnum not being
set. Commit 298a1665a guarantees that *pnum is 0 (and not uninitialized
garbage) - but that still violates the contract that we (want to) have
that all drivers either make progress or return an error (setting pnum
to 0 should only be done at EOF or on error).
Oh. The pre-existing code DID set pnum to a non-zero value, as a side
effect of block_status(); the new code fails to do so. So it is not
pre-existing; good catch!
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
