static int qcow2_write_snapshots(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; QCowSnapshot *sn; QCowSnapshotHeader h; QCowSnapshotExtraData extra; int i, name_size, id_str_size, snapshots_size; struct { uint32_t nb_snapshots; uint64_t snapshots_offset; } QEMU_PACKED header_data; int64_t offset, snapshots_offset; int ret; /* compute the size of the snapshots */ offset = 0; for(i = 0; i < s->nb_snapshots; i++) { sn = s->snapshots + i; offset = align_offset(offset, 8); offset += sizeof(h); offset += sizeof(extra); offset += strlen(sn->id_str); offset += strlen(sn->name); } snapshots_size = offset; /* Allocate space for the new snapshot list */ snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size); bdrv_flush(bs->file); offset = snapshots_offset; if (offset < 0) { return offset; } /* Write all snapshots to the new list */ for(i = 0; i < s->nb_snapshots; i++) { sn = s->snapshots + i; memset(&h, 0, sizeof(h)); h.l1_table_offset = cpu_to_be64(sn->l1_table_offset); h.l1_size = cpu_to_be32(sn->l1_size); /* If it doesn't fit in 32 bit, older implementations should treat it * as a disk-only snapshot rather than truncate the VM state */ if (sn->vm_state_size <= 0xffffffff) { h.vm_state_size = cpu_to_be32(sn->vm_state_size); } h.date_sec = cpu_to_be32(sn->date_sec); h.date_nsec = cpu_to_be32(sn->date_nsec); h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec); h.extra_data_size = cpu_to_be32(sizeof(extra)); memset(&extra, 0, sizeof(extra)); extra.vm_state_size_large = cpu_to_be64(sn->vm_state_size); extra.disk_size = cpu_to_be64(sn->disk_size); id_str_size = strlen(sn->id_str); name_size = strlen(sn->name); h.id_str_size = cpu_to_be16(id_str_size); h.name_size = cpu_to_be16(name_size); offset = align_offset(offset, 8); ret = bdrv_pwrite(bs->file, offset, &h, sizeof(h)); if (ret < 0) { goto fail; } offset += sizeof(h); ret = bdrv_pwrite(bs->file, offset, &extra, sizeof(extra)); if (ret < 0) { goto fail; } offset += sizeof(extra); ret = bdrv_pwrite(bs->file, offset, sn->id_str, id_str_size); if (ret < 0) { goto fail; } offset += id_str_size; ret = bdrv_pwrite(bs->file, offset, sn->name, name_size); if (ret < 0) { goto fail; } offset += name_size; } /* * Update the header to point to the new snapshot table. This requires the * new table and its refcounts to be stable on disk. */ ret = bdrv_flush(bs); if (ret < 0) { goto fail; } QEMU_BUILD_BUG_ON(offsetof(QCowHeader, snapshots_offset) != offsetof(QCowHeader, nb_snapshots) + sizeof(header_data.nb_snapshots)); header_data.nb_snapshots = cpu_to_be32(s->nb_snapshots); header_data.snapshots_offset = cpu_to_be64(snapshots_offset); ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots), &header_data, sizeof(header_data)); if (ret < 0) { goto fail; } /* free the old snapshot table */ qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size); s->snapshots_offset = snapshots_offset; s->snapshots_size = snapshots_size; return 0; fail: return ret; }