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parallels: naive implementation of parallels_co_pdiscard

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* Discarding with backing stores is not supported by the format.
* There is no buffering/queueing of the discard operation.
* Only operations aligned to the cluster are supported.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
This commit is contained in:
Denis V. Lunev 2023-09-18 20:00:57 +02:00
parent 66d201dd5a
commit c54fb43507
1 changed files with 46 additions and 0 deletions
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46
block/parallels.c
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@ -537,6 +537,51 @@ parallels_co_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
return ret;
}
static int coroutine_fn GRAPH_RDLOCK
parallels_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
{
int ret = 0;
uint32_t cluster, count;
BDRVParallelsState *s = bs->opaque;
/*
* The image does not support ZERO mark inside the BAT, which means that
* stale data could be exposed from the backing file.
*/
if (bs->backing) {
return -ENOTSUP;
}
if (!QEMU_IS_ALIGNED(offset, s->cluster_size)) {
return -ENOTSUP;
} else if (!QEMU_IS_ALIGNED(bytes, s->cluster_size)) {
return -ENOTSUP;
}
cluster = offset / s->cluster_size;
count = bytes / s->cluster_size;
qemu_co_mutex_lock(&s->lock);
for (; count > 0; cluster++, count--) {
int64_t host_off = bat2sect(s, cluster) << BDRV_SECTOR_BITS;
if (host_off == 0) {
continue;
}
ret = bdrv_co_pdiscard(bs->file, host_off, s->cluster_size);
if (ret < 0) {
goto done;
}
parallels_set_bat_entry(s, cluster, 0);
bitmap_clear(s->used_bmap, host_cluster_index(s, host_off), 1);
}
done:
qemu_co_mutex_unlock(&s->lock);
return ret;
}
static void parallels_check_unclean(BlockDriverState *bs,
BdrvCheckResult *res,
BdrvCheckMode fix)
@ -1417,6 +1462,7 @@ static BlockDriver bdrv_parallels = {
.bdrv_co_create = parallels_co_create,
.bdrv_co_create_opts = parallels_co_create_opts,
.bdrv_co_check = parallels_co_check,
.bdrv_co_pdiscard = parallels_co_pdiscard,
};
static void bdrv_parallels_init(void)