return ret;
}
+
+static bool is_zero_cluster(BlockDriverState *bs, int64_t start)
+{
+ BDRVQcow2State *s = bs->opaque;
+ int nr;
+ BlockDriverState *file;
+ int64_t res = bdrv_get_block_status_above(bs, NULL, start,
+ s->cluster_sectors, &nr, &file);
+ return res >= 0 && ((res & BDRV_BLOCK_ZERO) || !(res & BDRV_BLOCK_DATA));
+}
+
+static bool is_zero_cluster_top_locked(BlockDriverState *bs, int64_t start)
+{
+ BDRVQcow2State *s = bs->opaque;
+ int nr = s->cluster_sectors;
+ uint64_t off;
+ int ret;
+
+ ret = qcow2_get_cluster_offset(bs, start << BDRV_SECTOR_BITS, &nr, &off);
+ return ret == QCOW2_CLUSTER_UNALLOCATED || ret == QCOW2_CLUSTER_ZERO;
+}
+
static coroutine_fn int qcow2_co_write_zeroes(BlockDriverState *bs,
int64_t sector_num, int nb_sectors, BdrvRequestFlags flags)
{
int ret;
BDRVQcow2State *s = bs->opaque;
- /* Emulate misaligned zero writes */
- if (sector_num % s->cluster_sectors || nb_sectors % s->cluster_sectors) {
- return -ENOTSUP;
+ int head = sector_num % s->cluster_sectors;
+ int tail = (sector_num + nb_sectors) % s->cluster_sectors;
+
+ if (head != 0 || tail != 0) {
+ int64_t cl_end = -1;
+
+ sector_num -= head;
+ nb_sectors += head;
+
+ if (tail != 0) {
+ nb_sectors += s->cluster_sectors - tail;
+ }
+
+ if (!is_zero_cluster(bs, sector_num)) {
+ return -ENOTSUP;
+ }
+
+ if (nb_sectors > s->cluster_sectors) {
+ /* Technically the request can cover 2 clusters, f.e. 4k write
+ at s->cluster_sectors - 2k offset. One of these cluster can
+ be zeroed, one unallocated */
+ cl_end = sector_num + nb_sectors - s->cluster_sectors;
+ if (!is_zero_cluster(bs, cl_end)) {
+ return -ENOTSUP;
+ }
+ }
+
+ qemu_co_mutex_lock(&s->lock);
+ /* We can have new write after previous check */
+ if (!is_zero_cluster_top_locked(bs, sector_num) ||
+ (cl_end > 0 && !is_zero_cluster_top_locked(bs, cl_end))) {
+ qemu_co_mutex_unlock(&s->lock);
+ return -ENOTSUP;
+ }
+ } else {
+ qemu_co_mutex_lock(&s->lock);
}
/* Whatever is left can use real zero clusters */
- qemu_co_mutex_lock(&s->lock);
- ret = qcow2_zero_clusters(bs, sector_num << BDRV_SECTOR_BITS,
- nb_sectors);
+ ret = qcow2_zero_clusters(bs, sector_num << BDRV_SECTOR_BITS, nb_sectors);
qemu_co_mutex_unlock(&s->lock);
return ret;