On 11/30/2017 03:51 AM, Vladimir Sementsov-Ogievskiy wrote:
12.10.2017 21:59, Eric Blake wrote:
We are gradually moving away from sector-based interfaces, towards
byte-based. Update the qcow2 driver accordingly.
For now, we are ignoring the 'want_zero' hint. However, it should
be relatively straightforward to honor the hint as a way to return
larger *pnum values when we have consecutive clusters with the same
data/zero status but which differ only in having non-consecutive
mappings.
useful thing (for example, to get several compressed clusters in one chunk,
but do not include following zero clusters). but should not the hint be
called want_mapping for it?
or may be we will move to "int hint_flags", which will include status flags
we a interested in?
Right now, there are only two public interfaces: bdrv_is_allocated
(want_zero is false), and bdrv_block_status (want_zero is true). You
may have a point that there could be further optimizations possible if
the caller has more control over what flags it is interested in, but
that should be a patch series for a later day; I'm already cramming
enough into this series, and it's already stretched out (first patches
went into 2.10), so I want it done.
Signed-off-by: Eric Blake <ebl...@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
-static int64_t coroutine_fn
qcow2_co_get_block_status(BlockDriverState *bs,
- int64_t sector_num, int nb_sectors, int *pnum,
BlockDriverState **file)
+static int coroutine_fn qcow2_co_block_status(BlockDriverState *bs,
+ bool want_zero,
+ int64_t offset, int64_t
count,
'count' is used instead of 'bytes' because of qcow2_get_cluster_offset
which wants int*..
Yes,...
+ int64_t *pnum, int64_t
*map,
+ BlockDriverState **file)
{
BDRVQcow2State *s = bs->opaque;
uint64_t cluster_offset;
int index_in_cluster, ret;
unsigned int bytes;
...because of that.
- int64_t status = 0;
+ int status = 0;
- bytes = MIN(INT_MAX, nb_sectors * BDRV_SECTOR_SIZE);
+ bytes = MIN(INT_MAX, count);
qemu_co_mutex_lock(&s->lock);
- ret = qcow2_get_cluster_offset(bs, sector_num <<
BDRV_SECTOR_BITS, &bytes,
- &cluster_offset);
+ ret = qcow2_get_cluster_offset(bs, offset, &bytes, &cluster_offset);
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
