int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors) { int max_discard; if (!bs->drv) { return -ENOMEDIUM; } else if (bdrv_check_request(bs, sector_num, nb_sectors)) { return -EIO; } else if (bs->read_only) { return -EROFS; } bdrv_reset_dirty(bs, sector_num, nb_sectors); /* Do nothing if disabled. */ if (!(bs->open_flags & BDRV_O_UNMAP)) { return 0; } if (!bs->drv->bdrv_co_discard && !bs->drv->bdrv_aio_discard) { return 0; } max_discard = bs->bl.max_discard ? bs->bl.max_discard : MAX_DISCARD_DEFAULT; while (nb_sectors > 0) { int ret; int num = nb_sectors; /* align request */ if (bs->bl.discard_alignment && num >= bs->bl.discard_alignment && sector_num % bs->bl.discard_alignment) { if (num > bs->bl.discard_alignment) { num = bs->bl.discard_alignment; } num -= sector_num % bs->bl.discard_alignment; } /* limit request size */ if (num > max_discard) { num = max_discard; } if (bs->drv->bdrv_co_discard) { ret = bs->drv->bdrv_co_discard(bs, sector_num, num); } else { BlockDriverAIOCB *acb; CoroutineIOCompletion co = { .coroutine = qemu_coroutine_self(), }; acb = bs->drv->bdrv_aio_discard(bs, sector_num, nb_sectors, bdrv_co_io_em_complete, &co); if (acb == NULL) { return -EIO; } else { qemu_coroutine_yield(); ret = co.ret; } } if (ret) { return ret; } sector_num += num; nb_sectors -= num; } return 0; }