/* * Block driver for the QCOW version 2 format * * Copyright (c) 2004-2006 Fabrice Bellard * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include "qemu-common.h" #include "block/block_int.h" #include "qemu/module.h" #include <zlib.h> #include "block/aes.h" #include "block/qcow2.h" #include "qemu/error-report.h" #include "qapi/qmp/qerror.h" #include "trace.h" /* Differences with QCOW: - Support for multiple incremental snapshots. - Memory management by reference counts. - Clusters which have a reference count of one have the bit QCOW_OFLAG_COPIED to optimize write performance. - Size of compressed clusters is stored in sectors to reduce bit usage in the cluster offsets. - Support for storing additional data (such as the VM state) in the snapshots. - If a backing store is used, the cluster size is not constrained (could be backported to QCOW). - L2 tables have always a size of one cluster. */ typedef struct { uint32_t magic; uint32_t len; } QCowExtension; #define QCOW2_EXT_MAGIC_END 0 #define QCOW2_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA #define QCOW2_EXT_MAGIC_FEATURE_TABLE 0x6803f857 static int qcow2_probe(const uint8_t *buf, int buf_size, const char *filename) { const QCowHeader *cow_header = (const void *)buf; if (buf_size >= sizeof(QCowHeader) && be32_to_cpu(cow_header->magic) == QCOW_MAGIC && be32_to_cpu(cow_header->version) >= 2) return 100; else return 0; } /* * read qcow2 extension and fill bs * start reading from start_offset * finish reading upon magic of value 0 or when end_offset reached * unknown magic is skipped (future extension this version knows nothing about) * return 0 upon success, non-0 otherwise */ static int qcow2_read_extensions(BlockDriverState *bs, uint64_t start_offset, uint64_t end_offset, void **p_feature_table) { BDRVQcowState *s = bs->opaque; QCowExtension ext; uint64_t offset; int ret; #ifdef DEBUG_EXT printf("qcow2_read_extensions: start=%ld end=%ld\n", start_offset, end_offset); #endif offset = start_offset; while (offset < end_offset) { #ifdef DEBUG_EXT /* Sanity check */ if (offset > s->cluster_size) printf("qcow2_read_extension: suspicious offset %lu\n", offset); printf("attempting to read extended header in offset %lu\n", offset); #endif if (bdrv_pread(bs->file, offset, &ext, sizeof(ext)) != sizeof(ext)) { fprintf(stderr, "qcow2_read_extension: ERROR: " "pread fail from offset %" PRIu64 "\n", offset); return 1; } be32_to_cpus(&ext.magic); be32_to_cpus(&ext.len); offset += sizeof(ext); #ifdef DEBUG_EXT printf("ext.magic = 0x%x\n", ext.magic); #endif if (ext.len > end_offset - offset) { error_report("Header extension too large"); return -EINVAL; } switch (ext.magic) { case QCOW2_EXT_MAGIC_END: return 0; case QCOW2_EXT_MAGIC_BACKING_FORMAT: if (ext.len >= sizeof(bs->backing_format)) { fprintf(stderr, "ERROR: ext_backing_format: len=%u too large" " (>=%zu)\n", ext.len, sizeof(bs->backing_format)); return 2; } if (bdrv_pread(bs->file, offset , bs->backing_format, ext.len) != ext.len) return 3; bs->backing_format[ext.len] = '\0'; #ifdef DEBUG_EXT printf("Qcow2: Got format extension %s\n", bs->backing_format); #endif break; case QCOW2_EXT_MAGIC_FEATURE_TABLE: if (p_feature_table != NULL) { void* feature_table = g_malloc0(ext.len + 2 * sizeof(Qcow2Feature)); ret = bdrv_pread(bs->file, offset , feature_table, ext.len); if (ret < 0) { return ret; } *p_feature_table = feature_table; } break; default: /* unknown magic - save it in case we need to rewrite the header */ { Qcow2UnknownHeaderExtension *uext; uext = g_malloc0(sizeof(*uext) + ext.len); uext->magic = ext.magic; uext->len = ext.len; QLIST_INSERT_HEAD(&s->unknown_header_ext, uext, next); ret = bdrv_pread(bs->file, offset , uext->data, uext->len); if (ret < 0) { return ret; } } break; } offset += ((ext.len + 7) & ~7); } return 0; } static void cleanup_unknown_header_ext(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; Qcow2UnknownHeaderExtension *uext, *next; QLIST_FOREACH_SAFE(uext, &s->unknown_header_ext, next, next) { QLIST_REMOVE(uext, next); g_free(uext); } } static void GCC_FMT_ATTR(2, 3) report_unsupported(BlockDriverState *bs, const char *fmt, ...) { char msg[64]; va_list ap; va_start(ap, fmt); vsnprintf(msg, sizeof(msg), fmt, ap); va_end(ap); qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE, bs->device_name, "qcow2", msg); } static void report_unsupported_feature(BlockDriverState *bs, Qcow2Feature *table, uint64_t mask) { while (table && table->name[0] != '\0') { if (table->type == QCOW2_FEAT_TYPE_INCOMPATIBLE) { if (mask & (1 << table->bit)) { report_unsupported(bs, "%.46s",table->name); mask &= ~(1 << table->bit); } } table++; } if (mask) { report_unsupported(bs, "Unknown incompatible feature: %" PRIx64, mask); } } /* * Sets the dirty bit and flushes afterwards if necessary. * * The incompatible_features bit is only set if the image file header was * updated successfully. Therefore it is not required to check the return * value of this function. */ int qcow2_mark_dirty(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; uint64_t val; int ret; assert(s->qcow_version >= 3); if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) { return 0; /* already dirty */ } val = cpu_to_be64(s->incompatible_features | QCOW2_INCOMPAT_DIRTY); ret = bdrv_pwrite(bs->file, offsetof(QCowHeader, incompatible_features), &val, sizeof(val)); if (ret < 0) { return ret; } ret = bdrv_flush(bs->file); if (ret < 0) { return ret; } /* Only treat image as dirty if the header was updated successfully */ s->incompatible_features |= QCOW2_INCOMPAT_DIRTY; return 0; } /* * Clears the dirty bit and flushes before if necessary. Only call this * function when there are no pending requests, it does not guard against * concurrent requests dirtying the image. */ static int qcow2_mark_clean(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) { int ret = bdrv_flush(bs); if (ret < 0) { return ret; } s->incompatible_features &= ~QCOW2_INCOMPAT_DIRTY; return qcow2_update_header(bs); } return 0; } static int qcow2_check(BlockDriverState *bs, BdrvCheckResult *result, BdrvCheckMode fix) { int ret = qcow2_check_refcounts(bs, result, fix); if (ret < 0) { return ret; } if (fix && result->check_errors == 0 && result->corruptions == 0) { return qcow2_mark_clean(bs); } return ret; } static int qcow2_open(BlockDriverState *bs, int flags) { BDRVQcowState *s = bs->opaque; int len, i, ret = 0; QCowHeader header; uint64_t ext_end; ret = bdrv_pread(bs->file, 0, &header, sizeof(header)); if (ret < 0) { goto fail; } be32_to_cpus(&header.magic); be32_to_cpus(&header.version); be64_to_cpus(&header.backing_file_offset); be32_to_cpus(&header.backing_file_size); be64_to_cpus(&header.size); be32_to_cpus(&header.cluster_bits); be32_to_cpus(&header.crypt_method); be64_to_cpus(&header.l1_table_offset); be32_to_cpus(&header.l1_size); be64_to_cpus(&header.refcount_table_offset); be32_to_cpus(&header.refcount_table_clusters); be64_to_cpus(&header.snapshots_offset); be32_to_cpus(&header.nb_snapshots); if (header.magic != QCOW_MAGIC) { ret = -EINVAL; goto fail; } if (header.version < 2 || header.version > 3) { report_unsupported(bs, "QCOW version %d", header.version); ret = -ENOTSUP; goto fail; } s->qcow_version = header.version; /* Initialise version 3 header fields */ if (header.version == 2) { header.incompatible_features = 0; header.compatible_features = 0; header.autoclear_features = 0; header.refcount_order = 4; header.header_length = 72; } else { be64_to_cpus(&header.incompatible_features); be64_to_cpus(&header.compatible_features); be64_to_cpus(&header.autoclear_features); be32_to_cpus(&header.refcount_order); be32_to_cpus(&header.header_length); } if (header.header_length > sizeof(header)) { s->unknown_header_fields_size = header.header_length - sizeof(header); s->unknown_header_fields = g_malloc(s->unknown_header_fields_size); ret = bdrv_pread(bs->file, sizeof(header), s->unknown_header_fields, s->unknown_header_fields_size); if (ret < 0) { goto fail; } } if (header.backing_file_offset) { ext_end = header.backing_file_offset; } else { ext_end = 1 << header.cluster_bits; } /* Handle feature bits */ s->incompatible_features = header.incompatible_features; s->compatible_features = header.compatible_features; s->autoclear_features = header.autoclear_features; if (s->incompatible_features & ~QCOW2_INCOMPAT_MASK) { void *feature_table = NULL; qcow2_read_extensions(bs, header.header_length, ext_end, &feature_table); report_unsupported_feature(bs, feature_table, s->incompatible_features & ~QCOW2_INCOMPAT_MASK); ret = -ENOTSUP; goto fail; } /* Check support for various header values */ if (header.refcount_order != 4) { report_unsupported(bs, "%d bit reference counts", 1 << header.refcount_order); ret = -ENOTSUP; goto fail; } if (header.cluster_bits < MIN_CLUSTER_BITS || header.cluster_bits > MAX_CLUSTER_BITS) { ret = -EINVAL; goto fail; } if (header.crypt_method > QCOW_CRYPT_AES) { ret = -EINVAL; goto fail; } s->crypt_method_header = header.crypt_method; if (s->crypt_method_header) { bs->encrypted = 1; } s->cluster_bits = header.cluster_bits; s->cluster_size = 1 << s->cluster_bits; s->cluster_sectors = 1 << (s->cluster_bits - 9); s->l2_bits = s->cluster_bits - 3; /* L2 is always one cluster */ s->l2_size = 1 << s->l2_bits; bs->total_sectors = header.size / 512; s->csize_shift = (62 - (s->cluster_bits - 8)); s->csize_mask = (1 << (s->cluster_bits - 8)) - 1; s->cluster_offset_mask = (1LL << s->csize_shift) - 1; s->refcount_table_offset = header.refcount_table_offset; s->refcount_table_size = header.refcount_table_clusters << (s->cluster_bits - 3); s->snapshots_offset = header.snapshots_offset; s->nb_snapshots = header.nb_snapshots; /* read the level 1 table */ s->l1_size = header.l1_size; s->l1_vm_state_index = size_to_l1(s, header.size); /* the L1 table must contain at least enough entries to put header.size bytes */ if (s->l1_size < s->l1_vm_state_index) { ret = -EINVAL; goto fail; } s->l1_table_offset = header.l1_table_offset; if (s->l1_size > 0) { s->l1_table = g_malloc0( align_offset(s->l1_size * sizeof(uint64_t), 512)); ret = bdrv_pread(bs->file, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)); if (ret < 0) { goto fail; } for(i = 0;i < s->l1_size; i++) { be64_to_cpus(&s->l1_table[i]); } } /* alloc L2 table/refcount block cache */ s->l2_table_cache = qcow2_cache_create(bs, L2_CACHE_SIZE); s->refcount_block_cache = qcow2_cache_create(bs, REFCOUNT_CACHE_SIZE); s->cluster_cache = g_malloc(s->cluster_size); /* one more sector for decompressed data alignment */ s->cluster_data = qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size + 512); s->cluster_cache_offset = -1; s->flags = flags; ret = qcow2_refcount_init(bs); if (ret != 0) { goto fail; } QLIST_INIT(&s->cluster_allocs); /* read qcow2 extensions */ if (qcow2_read_extensions(bs, header.header_length, ext_end, NULL)) { ret = -EINVAL; goto fail; } /* read the backing file name */ if (header.backing_file_offset != 0) { len = header.backing_file_size; if (len > 1023) { len = 1023; } ret = bdrv_pread(bs->file, header.backing_file_offset, bs->backing_file, len); if (ret < 0) { goto fail; } bs->backing_file[len] = '\0'; } ret = qcow2_read_snapshots(bs); if (ret < 0) { goto fail; } /* Clear unknown autoclear feature bits */ if (!bs->read_only && s->autoclear_features != 0) { s->autoclear_features = 0; ret = qcow2_update_header(bs); if (ret < 0) { goto fail; } } /* Initialise locks */ qemu_co_mutex_init(&s->lock); /* Repair image if dirty */ if (!(flags & BDRV_O_CHECK) && !bs->read_only && (s->incompatible_features & QCOW2_INCOMPAT_DIRTY)) { BdrvCheckResult result = {0}; ret = qcow2_check(bs, &result, BDRV_FIX_ERRORS); if (ret < 0) { goto fail; } } #ifdef DEBUG_ALLOC { BdrvCheckResult result = {0}; qcow2_check_refcounts(bs, &result, 0); } #endif return ret; fail: g_free(s->unknown_header_fields); cleanup_unknown_header_ext(bs); qcow2_free_snapshots(bs); qcow2_refcount_close(bs); g_free(s->l1_table); if (s->l2_table_cache) { qcow2_cache_destroy(bs, s->l2_table_cache); } g_free(s->cluster_cache); qemu_vfree(s->cluster_data); return ret; } static int qcow2_set_key(BlockDriverState *bs, const char *key) { BDRVQcowState *s = bs->opaque; uint8_t keybuf[16]; int len, i; memset(keybuf, 0, 16); len = strlen(key); if (len > 16) len = 16; /* XXX: we could compress the chars to 7 bits to increase entropy */ for(i = 0;i < len;i++) { keybuf[i] = key[i]; } s->crypt_method = s->crypt_method_header; if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0) return -1; if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0) return -1; #if 0 /* test */ { uint8_t in[16]; uint8_t out[16]; uint8_t tmp[16]; for(i=0;i<16;i++) in[i] = i; AES_encrypt(in, tmp, &s->aes_encrypt_key); AES_decrypt(tmp, out, &s->aes_decrypt_key); for(i = 0; i < 16; i++) printf(" %02x", tmp[i]); printf("\n"); for(i = 0; i < 16; i++) printf(" %02x", out[i]); printf("\n"); } #endif return 0; } /* We have nothing to do for QCOW2 reopen, stubs just return * success */ static int qcow2_reopen_prepare(BDRVReopenState *state, BlockReopenQueue *queue, Error **errp) { return 0; } static int coroutine_fn qcow2_co_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum) { BDRVQcowState *s = bs->opaque; uint64_t cluster_offset; int ret; *pnum = nb_sectors; /* FIXME We can get errors here, but the bdrv_co_is_allocated interface * can't pass them on today */ qemu_co_mutex_lock(&s->lock); ret = qcow2_get_cluster_offset(bs, sector_num << 9, pnum, &cluster_offset); qemu_co_mutex_unlock(&s->lock); if (ret < 0) { *pnum = 0; } return (cluster_offset != 0); } /* handle reading after the end of the backing file */ int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov, int64_t sector_num, int nb_sectors) { int n1; if ((sector_num + nb_sectors) <= bs->total_sectors) return nb_sectors; if (sector_num >= bs->total_sectors) n1 = 0; else n1 = bs->total_sectors - sector_num; qemu_iovec_memset(qiov, 512 * n1, 0, 512 * (nb_sectors - n1)); return n1; } static coroutine_fn int qcow2_co_readv(BlockDriverState *bs, int64_t sector_num, int remaining_sectors, QEMUIOVector *qiov) { BDRVQcowState *s = bs->opaque; int index_in_cluster, n1; int ret; int cur_nr_sectors; /* number of sectors in current iteration */ uint64_t cluster_offset = 0; uint64_t bytes_done = 0; QEMUIOVector hd_qiov; uint8_t *cluster_data = NULL; qemu_iovec_init(&hd_qiov, qiov->niov); qemu_co_mutex_lock(&s->lock); while (remaining_sectors != 0) { /* prepare next request */ cur_nr_sectors = remaining_sectors; if (s->crypt_method) { cur_nr_sectors = MIN(cur_nr_sectors, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors); } ret = qcow2_get_cluster_offset(bs, sector_num << 9, &cur_nr_sectors, &cluster_offset); if (ret < 0) { goto fail; } index_in_cluster = sector_num & (s->cluster_sectors - 1); qemu_iovec_reset(&hd_qiov); qemu_iovec_concat(&hd_qiov, qiov, bytes_done, cur_nr_sectors * 512); switch (ret) { case QCOW2_CLUSTER_UNALLOCATED: if (bs->backing_hd) { /* read from the base image */ n1 = qcow2_backing_read1(bs->backing_hd, &hd_qiov, sector_num, cur_nr_sectors); if (n1 > 0) { BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO); qemu_co_mutex_unlock(&s->lock); ret = bdrv_co_readv(bs->backing_hd, sector_num, n1, &hd_qiov); qemu_co_mutex_lock(&s->lock); if (ret < 0) { goto fail; } } } else { /* Note: in this case, no need to wait */ qemu_iovec_memset(&hd_qiov, 0, 0, 512 * cur_nr_sectors); } break; case QCOW2_CLUSTER_ZERO: if (s->qcow_version < 3) { ret = -EIO; goto fail; } qemu_iovec_memset(&hd_qiov, 0, 0, 512 * cur_nr_sectors); break; case QCOW2_CLUSTER_COMPRESSED: /* add AIO support for compressed blocks ? */ ret = qcow2_decompress_cluster(bs, cluster_offset); if (ret < 0) { goto fail; } qemu_iovec_from_buf(&hd_qiov, 0, s->cluster_cache + index_in_cluster * 512, 512 * cur_nr_sectors); break; case QCOW2_CLUSTER_NORMAL: if ((cluster_offset & 511) != 0) { ret = -EIO; goto fail; } if (s->crypt_method) { /* * For encrypted images, read everything into a temporary * contiguous buffer on which the AES functions can work. */ if (!cluster_data) { cluster_data = qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size); } assert(cur_nr_sectors <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors); qemu_iovec_reset(&hd_qiov); qemu_iovec_add(&hd_qiov, cluster_data, 512 * cur_nr_sectors); } BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO); qemu_co_mutex_unlock(&s->lock); ret = bdrv_co_readv(bs->file, (cluster_offset >> 9) + index_in_cluster, cur_nr_sectors, &hd_qiov); qemu_co_mutex_lock(&s->lock); if (ret < 0) { goto fail; } if (s->crypt_method) { qcow2_encrypt_sectors(s, sector_num, cluster_data, cluster_data, cur_nr_sectors, 0, &s->aes_decrypt_key); qemu_iovec_from_buf(qiov, bytes_done, cluster_data, 512 * cur_nr_sectors); } break; default: g_assert_not_reached(); ret = -EIO; goto fail; } remaining_sectors -= cur_nr_sectors; sector_num += cur_nr_sectors; bytes_done += cur_nr_sectors * 512; } ret = 0; fail: qemu_co_mutex_unlock(&s->lock); qemu_iovec_destroy(&hd_qiov); qemu_vfree(cluster_data); return ret; } static coroutine_fn int qcow2_co_writev(BlockDriverState *bs, int64_t sector_num, int remaining_sectors, QEMUIOVector *qiov) { BDRVQcowState *s = bs->opaque; int index_in_cluster; int n_end; int ret; int cur_nr_sectors; /* number of sectors in current iteration */ uint64_t cluster_offset; QEMUIOVector hd_qiov; uint64_t bytes_done = 0; uint8_t *cluster_data = NULL; QCowL2Meta *l2meta; trace_qcow2_writev_start_req(qemu_coroutine_self(), sector_num, remaining_sectors); qemu_iovec_init(&hd_qiov, qiov->niov); s->cluster_cache_offset = -1; /* disable compressed cache */ qemu_co_mutex_lock(&s->lock); while (remaining_sectors != 0) { l2meta = NULL; trace_qcow2_writev_start_part(qemu_coroutine_self()); index_in_cluster = sector_num & (s->cluster_sectors - 1); n_end = index_in_cluster + remaining_sectors; if (s->crypt_method && n_end > QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors) { n_end = QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors; } ret = qcow2_alloc_cluster_offset(bs, sector_num << 9, index_in_cluster, n_end, &cur_nr_sectors, &cluster_offset, &l2meta); if (ret < 0) { goto fail; } assert((cluster_offset & 511) == 0); qemu_iovec_reset(&hd_qiov); qemu_iovec_concat(&hd_qiov, qiov, bytes_done, cur_nr_sectors * 512); if (s->crypt_method) { if (!cluster_data) { cluster_data = qemu_blockalign(bs, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size); } assert(hd_qiov.size <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size); qemu_iovec_to_buf(&hd_qiov, 0, cluster_data, hd_qiov.size); qcow2_encrypt_sectors(s, sector_num, cluster_data, cluster_data, cur_nr_sectors, 1, &s->aes_encrypt_key); qemu_iovec_reset(&hd_qiov); qemu_iovec_add(&hd_qiov, cluster_data, cur_nr_sectors * 512); } qemu_co_mutex_unlock(&s->lock); BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO); trace_qcow2_writev_data(qemu_coroutine_self(), (cluster_offset >> 9) + index_in_cluster); ret = bdrv_co_writev(bs->file, (cluster_offset >> 9) + index_in_cluster, cur_nr_sectors, &hd_qiov); qemu_co_mutex_lock(&s->lock); if (ret < 0) { goto fail; } if (l2meta != NULL) { ret = qcow2_alloc_cluster_link_l2(bs, l2meta); if (ret < 0) { goto fail; } /* Take the request off the list of running requests */ if (l2meta->nb_clusters != 0) { QLIST_REMOVE(l2meta, next_in_flight); } qemu_co_mutex_unlock(&s->lock); qemu_co_queue_restart_all(&l2meta->dependent_requests); qemu_co_mutex_lock(&s->lock); g_free(l2meta); l2meta = NULL; } remaining_sectors -= cur_nr_sectors; sector_num += cur_nr_sectors; bytes_done += cur_nr_sectors * 512; trace_qcow2_writev_done_part(qemu_coroutine_self(), cur_nr_sectors); } ret = 0; fail: qemu_co_mutex_unlock(&s->lock); if (l2meta != NULL) { if (l2meta->nb_clusters != 0) { QLIST_REMOVE(l2meta, next_in_flight); } qemu_co_queue_restart_all(&l2meta->dependent_requests); g_free(l2meta); } qemu_iovec_destroy(&hd_qiov); qemu_vfree(cluster_data); trace_qcow2_writev_done_req(qemu_coroutine_self(), ret); return ret; } static void qcow2_close(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; g_free(s->l1_table); qcow2_cache_flush(bs, s->l2_table_cache); qcow2_cache_flush(bs, s->refcount_block_cache); qcow2_mark_clean(bs); qcow2_cache_destroy(bs, s->l2_table_cache); qcow2_cache_destroy(bs, s->refcount_block_cache); g_free(s->unknown_header_fields); cleanup_unknown_header_ext(bs); g_free(s->cluster_cache); qemu_vfree(s->cluster_data); qcow2_refcount_close(bs); qcow2_free_snapshots(bs); } static void qcow2_invalidate_cache(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; int flags = s->flags; AES_KEY aes_encrypt_key; AES_KEY aes_decrypt_key; uint32_t crypt_method = 0; /* * Backing files are read-only which makes all of their metadata immutable, * that means we don't have to worry about reopening them here. */ if (s->crypt_method) { crypt_method = s->crypt_method; memcpy(&aes_encrypt_key, &s->aes_encrypt_key, sizeof(aes_encrypt_key)); memcpy(&aes_decrypt_key, &s->aes_decrypt_key, sizeof(aes_decrypt_key)); } qcow2_close(bs); memset(s, 0, sizeof(BDRVQcowState)); qcow2_open(bs, flags); if (crypt_method) { s->crypt_method = crypt_method; memcpy(&s->aes_encrypt_key, &aes_encrypt_key, sizeof(aes_encrypt_key)); memcpy(&s->aes_decrypt_key, &aes_decrypt_key, sizeof(aes_decrypt_key)); } } static size_t header_ext_add(char *buf, uint32_t magic, const void *s, size_t len, size_t buflen) { QCowExtension *ext_backing_fmt = (QCowExtension*) buf; size_t ext_len = sizeof(QCowExtension) + ((len + 7) & ~7); if (buflen < ext_len) { return -ENOSPC; } *ext_backing_fmt = (QCowExtension) { .magic = cpu_to_be32(magic), .len = cpu_to_be32(len), }; memcpy(buf + sizeof(QCowExtension), s, len); return ext_len; } /* * Updates the qcow2 header, including the variable length parts of it, i.e. * the backing file name and all extensions. qcow2 was not designed to allow * such changes, so if we run out of space (we can only use the first cluster) * this function may fail. * * Returns 0 on success, -errno in error cases. */ int qcow2_update_header(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; QCowHeader *header; char *buf; size_t buflen = s->cluster_size; int ret; uint64_t total_size; uint32_t refcount_table_clusters; size_t header_length; Qcow2UnknownHeaderExtension *uext; buf = qemu_blockalign(bs, buflen); /* Header structure */ header = (QCowHeader*) buf; if (buflen < sizeof(*header)) { ret = -ENOSPC; goto fail; } header_length = sizeof(*header) + s->unknown_header_fields_size; total_size = bs->total_sectors * BDRV_SECTOR_SIZE; refcount_table_clusters = s->refcount_table_size >> (s->cluster_bits - 3); *header = (QCowHeader) { /* Version 2 fields */ .magic = cpu_to_be32(QCOW_MAGIC), .version = cpu_to_be32(s->qcow_version), .backing_file_offset = 0, .backing_file_size = 0, .cluster_bits = cpu_to_be32(s->cluster_bits), .size = cpu_to_be64(total_size), .crypt_method = cpu_to_be32(s->crypt_method_header), .l1_size = cpu_to_be32(s->l1_size), .l1_table_offset = cpu_to_be64(s->l1_table_offset), .refcount_table_offset = cpu_to_be64(s->refcount_table_offset), .refcount_table_clusters = cpu_to_be32(refcount_table_clusters), .nb_snapshots = cpu_to_be32(s->nb_snapshots), .snapshots_offset = cpu_to_be64(s->snapshots_offset), /* Version 3 fields */ .incompatible_features = cpu_to_be64(s->incompatible_features), .compatible_features = cpu_to_be64(s->compatible_features), .autoclear_features = cpu_to_be64(s->autoclear_features), .refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT), .header_length = cpu_to_be32(header_length), }; /* For older versions, write a shorter header */ switch (s->qcow_version) { case 2: ret = offsetof(QCowHeader, incompatible_features); break; case 3: ret = sizeof(*header); break; default: ret = -EINVAL; goto fail; } buf += ret; buflen -= ret; memset(buf, 0, buflen); /* Preserve any unknown field in the header */ if (s->unknown_header_fields_size) { if (buflen < s->unknown_header_fields_size) { ret = -ENOSPC; goto fail; } memcpy(buf, s->unknown_header_fields, s->unknown_header_fields_size); buf += s->unknown_header_fields_size; buflen -= s->unknown_header_fields_size; } /* Backing file format header extension */ if (*bs->backing_format) { ret = header_ext_add(buf, QCOW2_EXT_MAGIC_BACKING_FORMAT, bs->backing_format, strlen(bs->backing_format), buflen); if (ret < 0) { goto fail; } buf += ret; buflen -= ret; } /* Feature table */ Qcow2Feature features[] = { { .type = QCOW2_FEAT_TYPE_INCOMPATIBLE, .bit = QCOW2_INCOMPAT_DIRTY_BITNR, .name = "dirty bit", }, { .type = QCOW2_FEAT_TYPE_COMPATIBLE, .bit = QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR, .name = "lazy refcounts", }, }; ret = header_ext_add(buf, QCOW2_EXT_MAGIC_FEATURE_TABLE, features, sizeof(features), buflen); if (ret < 0) { goto fail; } buf += ret; buflen -= ret; /* Keep unknown header extensions */ QLIST_FOREACH(uext, &s->unknown_header_ext, next) { ret = header_ext_add(buf, uext->magic, uext->data, uext->len, buflen); if (ret < 0) { goto fail; } buf += ret; buflen -= ret; } /* End of header extensions */ ret = header_ext_add(buf, QCOW2_EXT_MAGIC_END, NULL, 0, buflen); if (ret < 0) { goto fail; } buf += ret; buflen -= ret; /* Backing file name */ if (*bs->backing_file) { size_t backing_file_len = strlen(bs->backing_file); if (buflen < backing_file_len) { ret = -ENOSPC; goto fail; } /* Using strncpy is ok here, since buf is not NUL-terminated. */ strncpy(buf, bs->backing_file, buflen); header->backing_file_offset = cpu_to_be64(buf - ((char*) header)); header->backing_file_size = cpu_to_be32(backing_file_len); } /* Write the new header */ ret = bdrv_pwrite(bs->file, 0, header, s->cluster_size); if (ret < 0) { goto fail; } ret = 0; fail: qemu_vfree(header); return ret; } static int qcow2_change_backing_file(BlockDriverState *bs, const char *backing_file, const char *backing_fmt) { pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: ""); pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: ""); return qcow2_update_header(bs); } static int preallocate(BlockDriverState *bs) { uint64_t nb_sectors; uint64_t offset; uint64_t host_offset = 0; int num; int ret; QCowL2Meta *meta; nb_sectors = bdrv_getlength(bs) >> 9; offset = 0; while (nb_sectors) { num = MIN(nb_sectors, INT_MAX >> 9); ret = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num, &host_offset, &meta); if (ret < 0) { return ret; } ret = qcow2_alloc_cluster_link_l2(bs, meta); if (ret < 0) { qcow2_free_any_clusters(bs, meta->alloc_offset, meta->nb_clusters); return ret; } /* There are no dependent requests, but we need to remove our request * from the list of in-flight requests */ if (meta != NULL) { QLIST_REMOVE(meta, next_in_flight); } /* TODO Preallocate data if requested */ nb_sectors -= num; offset += num << 9; } /* * It is expected that the image file is large enough to actually contain * all of the allocated clusters (otherwise we get failing reads after * EOF). Extend the image to the last allocated sector. */ if (host_offset != 0) { uint8_t buf[512]; memset(buf, 0, 512); ret = bdrv_write(bs->file, (host_offset >> 9) + num - 1, buf, 1); if (ret < 0) { return ret; } } return 0; } static int qcow2_create2(const char *filename, int64_t total_size, const char *backing_file, const char *backing_format, int flags, size_t cluster_size, int prealloc, QEMUOptionParameter *options, int version) { /* Calculate cluster_bits */ int cluster_bits; cluster_bits = ffs(cluster_size) - 1; if (cluster_bits < MIN_CLUSTER_BITS || cluster_bits > MAX_CLUSTER_BITS || (1 << cluster_bits) != cluster_size) { error_report( "Cluster size must be a power of two between %d and %dk", 1 << MIN_CLUSTER_BITS, 1 << (MAX_CLUSTER_BITS - 10)); return -EINVAL; } /* * Open the image file and write a minimal qcow2 header. * * We keep things simple and start with a zero-sized image. We also * do without refcount blocks or a L1 table for now. We'll fix the * inconsistency later. * * We do need a refcount table because growing the refcount table means * allocating two new refcount blocks - the seconds of which would be at * 2 GB for 64k clusters, and we don't want to have a 2 GB initial file * size for any qcow2 image. */ BlockDriverState* bs; QCowHeader header; uint8_t* refcount_table; int ret; ret = bdrv_create_file(filename, options); if (ret < 0) { return ret; } ret = bdrv_file_open(&bs, filename, BDRV_O_RDWR); if (ret < 0) { return ret; } /* Write the header */ memset(&header, 0, sizeof(header)); header.magic = cpu_to_be32(QCOW_MAGIC); header.version = cpu_to_be32(version); header.cluster_bits = cpu_to_be32(cluster_bits); header.size = cpu_to_be64(0); header.l1_table_offset = cpu_to_be64(0); header.l1_size = cpu_to_be32(0); header.refcount_table_offset = cpu_to_be64(cluster_size); header.refcount_table_clusters = cpu_to_be32(1); header.refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT); header.header_length = cpu_to_be32(sizeof(header)); if (flags & BLOCK_FLAG_ENCRYPT) { header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES); } else { header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE); } if (flags & BLOCK_FLAG_LAZY_REFCOUNTS) { header.compatible_features |= cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS); } ret = bdrv_pwrite(bs, 0, &header, sizeof(header)); if (ret < 0) { goto out; } /* Write an empty refcount table */ refcount_table = g_malloc0(cluster_size); ret = bdrv_pwrite(bs, cluster_size, refcount_table, cluster_size); g_free(refcount_table); if (ret < 0) { goto out; } bdrv_close(bs); /* * And now open the image and make it consistent first (i.e. increase the * refcount of the cluster that is occupied by the header and the refcount * table) */ BlockDriver* drv = bdrv_find_format("qcow2"); assert(drv != NULL); ret = bdrv_open(bs, filename, BDRV_O_RDWR | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH, drv); if (ret < 0) { goto out; } ret = qcow2_alloc_clusters(bs, 2 * cluster_size); if (ret < 0) { goto out; } else if (ret != 0) { error_report("Huh, first cluster in empty image is already in use?"); abort(); } /* Okay, now that we have a valid image, let's give it the right size */ ret = bdrv_truncate(bs, total_size * BDRV_SECTOR_SIZE); if (ret < 0) { goto out; } /* Want a backing file? There you go.*/ if (backing_file) { ret = bdrv_change_backing_file(bs, backing_file, backing_format); if (ret < 0) { goto out; } } /* And if we're supposed to preallocate metadata, do that now */ if (prealloc) { BDRVQcowState *s = bs->opaque; qemu_co_mutex_lock(&s->lock); ret = preallocate(bs); qemu_co_mutex_unlock(&s->lock); if (ret < 0) { goto out; } } ret = 0; out: bdrv_delete(bs); return ret; } static int qcow2_create(const char *filename, QEMUOptionParameter *options) { const char *backing_file = NULL; const char *backing_fmt = NULL; uint64_t sectors = 0; int flags = 0; size_t cluster_size = DEFAULT_CLUSTER_SIZE; int prealloc = 0; int version = 2; /* Read out options */ while (options && options->name) { if (!strcmp(options->name, BLOCK_OPT_SIZE)) { sectors = options->value.n / 512; } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FILE)) { backing_file = options->value.s; } else if (!strcmp(options->name, BLOCK_OPT_BACKING_FMT)) { backing_fmt = options->value.s; } else if (!strcmp(options->name, BLOCK_OPT_ENCRYPT)) { flags |= options->value.n ? BLOCK_FLAG_ENCRYPT : 0; } else if (!strcmp(options->name, BLOCK_OPT_CLUSTER_SIZE)) { if (options->value.n) { cluster_size = options->value.n; } } else if (!strcmp(options->name, BLOCK_OPT_PREALLOC)) { if (!options->value.s || !strcmp(options->value.s, "off")) { prealloc = 0; } else if (!strcmp(options->value.s, "metadata")) { prealloc = 1; } else { fprintf(stderr, "Invalid preallocation mode: '%s'\n", options->value.s); return -EINVAL; } } else if (!strcmp(options->name, BLOCK_OPT_COMPAT_LEVEL)) { if (!options->value.s || !strcmp(options->value.s, "0.10")) { version = 2; } else if (!strcmp(options->value.s, "1.1")) { version = 3; } else { fprintf(stderr, "Invalid compatibility level: '%s'\n", options->value.s); return -EINVAL; } } else if (!strcmp(options->name, BLOCK_OPT_LAZY_REFCOUNTS)) { flags |= options->value.n ? BLOCK_FLAG_LAZY_REFCOUNTS : 0; } options++; } if (backing_file && prealloc) { fprintf(stderr, "Backing file and preallocation cannot be used at " "the same time\n"); return -EINVAL; } if (version < 3 && (flags & BLOCK_FLAG_LAZY_REFCOUNTS)) { fprintf(stderr, "Lazy refcounts only supported with compatibility " "level 1.1 and above (use compat=1.1 or greater)\n"); return -EINVAL; } return qcow2_create2(filename, sectors, backing_file, backing_fmt, flags, cluster_size, prealloc, options, version); } static int qcow2_make_empty(BlockDriverState *bs) { #if 0 /* XXX: not correct */ BDRVQcowState *s = bs->opaque; uint32_t l1_length = s->l1_size * sizeof(uint64_t); int ret; memset(s->l1_table, 0, l1_length); if (bdrv_pwrite(bs->file, s->l1_table_offset, s->l1_table, l1_length) < 0) return -1; ret = bdrv_truncate(bs->file, s->l1_table_offset + l1_length); if (ret < 0) return ret; l2_cache_reset(bs); #endif return 0; } static coroutine_fn int qcow2_co_write_zeroes(BlockDriverState *bs, int64_t sector_num, int nb_sectors) { int ret; BDRVQcowState *s = bs->opaque; /* Emulate misaligned zero writes */ if (sector_num % s->cluster_sectors || nb_sectors % s->cluster_sectors) { return -ENOTSUP; } /* 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); qemu_co_mutex_unlock(&s->lock); return ret; } static coroutine_fn int qcow2_co_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors) { int ret; BDRVQcowState *s = bs->opaque; qemu_co_mutex_lock(&s->lock); ret = qcow2_discard_clusters(bs, sector_num << BDRV_SECTOR_BITS, nb_sectors); qemu_co_mutex_unlock(&s->lock); return ret; } static int qcow2_truncate(BlockDriverState *bs, int64_t offset) { BDRVQcowState *s = bs->opaque; int ret, new_l1_size; if (offset & 511) { error_report("The new size must be a multiple of 512"); return -EINVAL; } /* cannot proceed if image has snapshots */ if (s->nb_snapshots) { error_report("Can't resize an image which has snapshots"); return -ENOTSUP; } /* shrinking is currently not supported */ if (offset < bs->total_sectors * 512) { error_report("qcow2 doesn't support shrinking images yet"); return -ENOTSUP; } new_l1_size = size_to_l1(s, offset); ret = qcow2_grow_l1_table(bs, new_l1_size, true); if (ret < 0) { return ret; } /* write updated header.size */ offset = cpu_to_be64(offset); ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, size), &offset, sizeof(uint64_t)); if (ret < 0) { return ret; } s->l1_vm_state_index = new_l1_size; return 0; } /* XXX: put compressed sectors first, then all the cluster aligned tables to avoid losing bytes in alignment */ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num, const uint8_t *buf, int nb_sectors) { BDRVQcowState *s = bs->opaque; z_stream strm; int ret, out_len; uint8_t *out_buf; uint64_t cluster_offset; if (nb_sectors == 0) { /* align end of file to a sector boundary to ease reading with sector based I/Os */ cluster_offset = bdrv_getlength(bs->file); cluster_offset = (cluster_offset + 511) & ~511; bdrv_truncate(bs->file, cluster_offset); return 0; } if (nb_sectors != s->cluster_sectors) return -EINVAL; out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128); /* best compression, small window, no zlib header */ memset(&strm, 0, sizeof(strm)); ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED, -12, 9, Z_DEFAULT_STRATEGY); if (ret != 0) { ret = -EINVAL; goto fail; } strm.avail_in = s->cluster_size; strm.next_in = (uint8_t *)buf; strm.avail_out = s->cluster_size; strm.next_out = out_buf; ret = deflate(&strm, Z_FINISH); if (ret != Z_STREAM_END && ret != Z_OK) { deflateEnd(&strm); ret = -EINVAL; goto fail; } out_len = strm.next_out - out_buf; deflateEnd(&strm); if (ret != Z_STREAM_END || out_len >= s->cluster_size) { /* could not compress: write normal cluster */ ret = bdrv_write(bs, sector_num, buf, s->cluster_sectors); if (ret < 0) { goto fail; } } else { cluster_offset = qcow2_alloc_compressed_cluster_offset(bs, sector_num << 9, out_len); if (!cluster_offset) { ret = -EIO; goto fail; } cluster_offset &= s->cluster_offset_mask; BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED); ret = bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len); if (ret < 0) { goto fail; } } ret = 0; fail: g_free(out_buf); return ret; } static coroutine_fn int qcow2_co_flush_to_os(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; int ret; qemu_co_mutex_lock(&s->lock); ret = qcow2_cache_flush(bs, s->l2_table_cache); if (ret < 0) { qemu_co_mutex_unlock(&s->lock); return ret; } if (qcow2_need_accurate_refcounts(s)) { ret = qcow2_cache_flush(bs, s->refcount_block_cache); if (ret < 0) { qemu_co_mutex_unlock(&s->lock); return ret; } } qemu_co_mutex_unlock(&s->lock); return 0; } static int64_t qcow2_vm_state_offset(BDRVQcowState *s) { return (int64_t)s->l1_vm_state_index << (s->cluster_bits + s->l2_bits); } static int qcow2_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) { BDRVQcowState *s = bs->opaque; bdi->cluster_size = s->cluster_size; bdi->vm_state_offset = qcow2_vm_state_offset(s); return 0; } #if 0 static void dump_refcounts(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; int64_t nb_clusters, k, k1, size; int refcount; size = bdrv_getlength(bs->file); nb_clusters = size_to_clusters(s, size); for(k = 0; k < nb_clusters;) { k1 = k; refcount = get_refcount(bs, k); k++; while (k < nb_clusters && get_refcount(bs, k) == refcount) k++; printf("%" PRId64 ": refcount=%d nb=%" PRId64 "\n", k, refcount, k - k1); } } #endif static int qcow2_save_vmstate(BlockDriverState *bs, const uint8_t *buf, int64_t pos, int size) { BDRVQcowState *s = bs->opaque; int growable = bs->growable; int ret; BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_SAVE); bs->growable = 1; ret = bdrv_pwrite(bs, qcow2_vm_state_offset(s) + pos, buf, size); bs->growable = growable; return ret; } static int qcow2_load_vmstate(BlockDriverState *bs, uint8_t *buf, int64_t pos, int size) { BDRVQcowState *s = bs->opaque; int growable = bs->growable; int ret; BLKDBG_EVENT(bs->file, BLKDBG_VMSTATE_LOAD); bs->growable = 1; ret = bdrv_pread(bs, qcow2_vm_state_offset(s) + pos, buf, size); bs->growable = growable; return ret; } static QEMUOptionParameter qcow2_create_options[] = { { .name = BLOCK_OPT_SIZE, .type = OPT_SIZE, .help = "Virtual disk size" }, { .name = BLOCK_OPT_COMPAT_LEVEL, .type = OPT_STRING, .help = "Compatibility level (0.10 or 1.1)" }, { .name = BLOCK_OPT_BACKING_FILE, .type = OPT_STRING, .help = "File name of a base image" }, { .name = BLOCK_OPT_BACKING_FMT, .type = OPT_STRING, .help = "Image format of the base image" }, { .name = BLOCK_OPT_ENCRYPT, .type = OPT_FLAG, .help = "Encrypt the image" }, { .name = BLOCK_OPT_CLUSTER_SIZE, .type = OPT_SIZE, .help = "qcow2 cluster size", .value = { .n = DEFAULT_CLUSTER_SIZE }, }, { .name = BLOCK_OPT_PREALLOC, .type = OPT_STRING, .help = "Preallocation mode (allowed values: off, metadata)" }, { .name = BLOCK_OPT_LAZY_REFCOUNTS, .type = OPT_FLAG, .help = "Postpone refcount updates", }, { NULL } }; static BlockDriver bdrv_qcow2 = { .format_name = "qcow2", .instance_size = sizeof(BDRVQcowState), .bdrv_probe = qcow2_probe, .bdrv_open = qcow2_open, .bdrv_close = qcow2_close, .bdrv_reopen_prepare = qcow2_reopen_prepare, .bdrv_create = qcow2_create, .bdrv_co_is_allocated = qcow2_co_is_allocated, .bdrv_set_key = qcow2_set_key, .bdrv_make_empty = qcow2_make_empty, .bdrv_co_readv = qcow2_co_readv, .bdrv_co_writev = qcow2_co_writev, .bdrv_co_flush_to_os = qcow2_co_flush_to_os, .bdrv_co_write_zeroes = qcow2_co_write_zeroes, .bdrv_co_discard = qcow2_co_discard, .bdrv_truncate = qcow2_truncate, .bdrv_write_compressed = qcow2_write_compressed, .bdrv_snapshot_create = qcow2_snapshot_create, .bdrv_snapshot_goto = qcow2_snapshot_goto, .bdrv_snapshot_delete = qcow2_snapshot_delete, .bdrv_snapshot_list = qcow2_snapshot_list, .bdrv_snapshot_load_tmp = qcow2_snapshot_load_tmp, .bdrv_get_info = qcow2_get_info, .bdrv_save_vmstate = qcow2_save_vmstate, .bdrv_load_vmstate = qcow2_load_vmstate, .bdrv_change_backing_file = qcow2_change_backing_file, .bdrv_invalidate_cache = qcow2_invalidate_cache, .create_options = qcow2_create_options, .bdrv_check = qcow2_check, }; static void bdrv_qcow2_init(void) { bdrv_register(&bdrv_qcow2); } block_init(bdrv_qcow2_init);