/* * 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_int.h" #include "module.h" #include #include "aes.h" #include "block/qcow2.h" #include "qemu-error.h" #include "qerror.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 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) >= QCOW_VERSION) 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) { QCowExtension ext; uint64_t offset; #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("attemting 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 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 offset = ((offset + ext.len + 7) & ~7); break; default: /* unknown magic -- just skip it */ offset = ((offset + ext.len + 7) & ~7); break; } } return 0; } static int qcow2_open(BlockDriverState *bs, int flags) { BDRVQcowState *s = bs->opaque; int len, i, ret = 0; QCowHeader header; uint64_t ext_end; bool writethrough; 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 != QCOW_VERSION) { char version[64]; snprintf(version, sizeof(version), "QCOW version %d", header.version); qerror_report(QERR_UNKNOWN_BLOCK_FORMAT_FEATURE, bs->device_name, "qcow2", version); 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 = qemu_mallocz( 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 */ writethrough = ((flags & BDRV_O_CACHE_WB) == 0); s->l2_table_cache = qcow2_cache_create(bs, L2_CACHE_SIZE, writethrough); s->refcount_block_cache = qcow2_cache_create(bs, REFCOUNT_CACHE_SIZE, writethrough); s->cluster_cache = qemu_malloc(s->cluster_size); /* one more sector for decompressed data alignment */ s->cluster_data = qemu_malloc(QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size + 512); s->cluster_cache_offset = -1; ret = qcow2_refcount_init(bs); if (ret != 0) { goto fail; } QLIST_INIT(&s->cluster_allocs); /* read qcow2 extensions */ if (header.backing_file_offset) { ext_end = header.backing_file_offset; } else { ext_end = s->cluster_size; } if (qcow2_read_extensions(bs, sizeof(header), ext_end)) { 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'; } if (qcow2_read_snapshots(bs) < 0) { ret = -EINVAL; goto fail; } #ifdef DEBUG_ALLOC qcow2_check_refcounts(bs); #endif return ret; fail: qcow2_free_snapshots(bs); qcow2_refcount_close(bs); qemu_free(s->l1_table); if (s->l2_table_cache) { qcow2_cache_destroy(bs, s->l2_table_cache); } qemu_free(s->cluster_cache); qemu_free(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; } static int qcow2_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum) { uint64_t cluster_offset; int ret; *pnum = nb_sectors; /* FIXME We can get errors here, but the bdrv_is_allocated interface can't * pass them on today */ ret = qcow2_get_cluster_offset(bs, sector_num << 9, pnum, &cluster_offset); 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_skip(qiov, 0, 512 * (nb_sectors - n1), 512 * n1); return n1; } typedef struct QCowAIOCB { BlockDriverAIOCB common; int64_t sector_num; QEMUIOVector *qiov; int remaining_sectors; int cur_nr_sectors; /* number of sectors in current iteration */ uint64_t bytes_done; uint64_t cluster_offset; uint8_t *cluster_data; BlockDriverAIOCB *hd_aiocb; QEMUIOVector hd_qiov; QEMUBH *bh; QCowL2Meta l2meta; QLIST_ENTRY(QCowAIOCB) next_depend; } QCowAIOCB; static void qcow2_aio_cancel(BlockDriverAIOCB *blockacb) { QCowAIOCB *acb = container_of(blockacb, QCowAIOCB, common); if (acb->hd_aiocb) bdrv_aio_cancel(acb->hd_aiocb); qemu_aio_release(acb); } static AIOPool qcow2_aio_pool = { .aiocb_size = sizeof(QCowAIOCB), .cancel = qcow2_aio_cancel, }; static void qcow2_aio_read_cb(void *opaque, int ret); static void qcow2_aio_read_bh(void *opaque) { QCowAIOCB *acb = opaque; qemu_bh_delete(acb->bh); acb->bh = NULL; qcow2_aio_read_cb(opaque, 0); } static int qcow2_schedule_bh(QEMUBHFunc *cb, QCowAIOCB *acb) { if (acb->bh) return -EIO; acb->bh = qemu_bh_new(cb, acb); if (!acb->bh) return -EIO; qemu_bh_schedule(acb->bh); return 0; } static void qcow2_aio_read_cb(void *opaque, int ret) { QCowAIOCB *acb = opaque; BlockDriverState *bs = acb->common.bs; BDRVQcowState *s = bs->opaque; int index_in_cluster, n1; acb->hd_aiocb = NULL; if (ret < 0) goto done; /* post process the read buffer */ if (!acb->cluster_offset) { /* nothing to do */ } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) { /* nothing to do */ } else { if (s->crypt_method) { qcow2_encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->cluster_data, acb->cur_nr_sectors, 0, &s->aes_decrypt_key); qemu_iovec_reset(&acb->hd_qiov); qemu_iovec_copy(&acb->hd_qiov, acb->qiov, acb->bytes_done, acb->cur_nr_sectors * 512); qemu_iovec_from_buffer(&acb->hd_qiov, acb->cluster_data, 512 * acb->cur_nr_sectors); } } acb->remaining_sectors -= acb->cur_nr_sectors; acb->sector_num += acb->cur_nr_sectors; acb->bytes_done += acb->cur_nr_sectors * 512; if (acb->remaining_sectors == 0) { /* request completed */ ret = 0; goto done; } /* prepare next AIO request */ acb->cur_nr_sectors = acb->remaining_sectors; if (s->crypt_method) { acb->cur_nr_sectors = MIN(acb->cur_nr_sectors, QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors); } ret = qcow2_get_cluster_offset(bs, acb->sector_num << 9, &acb->cur_nr_sectors, &acb->cluster_offset); if (ret < 0) { goto done; } index_in_cluster = acb->sector_num & (s->cluster_sectors - 1); qemu_iovec_reset(&acb->hd_qiov); qemu_iovec_copy(&acb->hd_qiov, acb->qiov, acb->bytes_done, acb->cur_nr_sectors * 512); if (!acb->cluster_offset) { if (bs->backing_hd) { /* read from the base image */ n1 = qcow2_backing_read1(bs->backing_hd, &acb->hd_qiov, acb->sector_num, acb->cur_nr_sectors); if (n1 > 0) { BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING_AIO); acb->hd_aiocb = bdrv_aio_readv(bs->backing_hd, acb->sector_num, &acb->hd_qiov, n1, qcow2_aio_read_cb, acb); if (acb->hd_aiocb == NULL) { ret = -EIO; goto done; } } else { ret = qcow2_schedule_bh(qcow2_aio_read_bh, acb); if (ret < 0) goto done; } } else { /* Note: in this case, no need to wait */ qemu_iovec_memset(&acb->hd_qiov, 0, 512 * acb->cur_nr_sectors); ret = qcow2_schedule_bh(qcow2_aio_read_bh, acb); if (ret < 0) goto done; } } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) { /* add AIO support for compressed blocks ? */ ret = qcow2_decompress_cluster(bs, acb->cluster_offset); if (ret < 0) { goto done; } qemu_iovec_from_buffer(&acb->hd_qiov, s->cluster_cache + index_in_cluster * 512, 512 * acb->cur_nr_sectors); ret = qcow2_schedule_bh(qcow2_aio_read_bh, acb); if (ret < 0) goto done; } else { if ((acb->cluster_offset & 511) != 0) { ret = -EIO; goto done; } if (s->crypt_method) { /* * For encrypted images, read everything into a temporary * contiguous buffer on which the AES functions can work. */ if (!acb->cluster_data) { acb->cluster_data = qemu_mallocz(QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size); } assert(acb->cur_nr_sectors <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors); qemu_iovec_reset(&acb->hd_qiov); qemu_iovec_add(&acb->hd_qiov, acb->cluster_data, 512 * acb->cur_nr_sectors); } BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO); acb->hd_aiocb = bdrv_aio_readv(bs->file, (acb->cluster_offset >> 9) + index_in_cluster, &acb->hd_qiov, acb->cur_nr_sectors, qcow2_aio_read_cb, acb); if (acb->hd_aiocb == NULL) { ret = -EIO; goto done; } } return; done: acb->common.cb(acb->common.opaque, ret); qemu_iovec_destroy(&acb->hd_qiov); qemu_aio_release(acb); } static QCowAIOCB *qcow2_aio_setup(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov, int nb_sectors, BlockDriverCompletionFunc *cb, void *opaque, int is_write) { QCowAIOCB *acb; acb = qemu_aio_get(&qcow2_aio_pool, bs, cb, opaque); if (!acb) return NULL; acb->hd_aiocb = NULL; acb->sector_num = sector_num; acb->qiov = qiov; qemu_iovec_init(&acb->hd_qiov, qiov->niov); acb->bytes_done = 0; acb->remaining_sectors = nb_sectors; acb->cur_nr_sectors = 0; acb->cluster_offset = 0; acb->l2meta.nb_clusters = 0; QLIST_INIT(&acb->l2meta.dependent_requests); return acb; } static BlockDriverAIOCB *qcow2_aio_readv(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov, int nb_sectors, BlockDriverCompletionFunc *cb, void *opaque) { QCowAIOCB *acb; acb = qcow2_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 0); if (!acb) return NULL; qcow2_aio_read_cb(acb, 0); return &acb->common; } static void qcow2_aio_write_cb(void *opaque, int ret); static void run_dependent_requests(QCowL2Meta *m) { QCowAIOCB *req; QCowAIOCB *next; /* Take the request off the list of running requests */ if (m->nb_clusters != 0) { QLIST_REMOVE(m, next_in_flight); } /* Restart all dependent requests */ QLIST_FOREACH_SAFE(req, &m->dependent_requests, next_depend, next) { qcow2_aio_write_cb(req, 0); } /* Empty the list for the next part of the request */ QLIST_INIT(&m->dependent_requests); } static void qcow2_aio_write_cb(void *opaque, int ret) { QCowAIOCB *acb = opaque; BlockDriverState *bs = acb->common.bs; BDRVQcowState *s = bs->opaque; int index_in_cluster; int n_end; acb->hd_aiocb = NULL; if (ret >= 0) { ret = qcow2_alloc_cluster_link_l2(bs, &acb->l2meta); } run_dependent_requests(&acb->l2meta); if (ret < 0) goto done; acb->remaining_sectors -= acb->cur_nr_sectors; acb->sector_num += acb->cur_nr_sectors; acb->bytes_done += acb->cur_nr_sectors * 512; if (acb->remaining_sectors == 0) { /* request completed */ ret = 0; goto done; } index_in_cluster = acb->sector_num & (s->cluster_sectors - 1); n_end = index_in_cluster + acb->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, acb->sector_num << 9, index_in_cluster, n_end, &acb->cur_nr_sectors, &acb->l2meta); if (ret < 0) { goto done; } acb->cluster_offset = acb->l2meta.cluster_offset; /* Need to wait for another request? If so, we are done for now. */ if (acb->l2meta.nb_clusters == 0 && acb->l2meta.depends_on != NULL) { QLIST_INSERT_HEAD(&acb->l2meta.depends_on->dependent_requests, acb, next_depend); return; } assert((acb->cluster_offset & 511) == 0); qemu_iovec_reset(&acb->hd_qiov); qemu_iovec_copy(&acb->hd_qiov, acb->qiov, acb->bytes_done, acb->cur_nr_sectors * 512); if (s->crypt_method) { if (!acb->cluster_data) { acb->cluster_data = qemu_mallocz(QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size); } assert(acb->hd_qiov.size <= QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size); qemu_iovec_to_buffer(&acb->hd_qiov, acb->cluster_data); qcow2_encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->cluster_data, acb->cur_nr_sectors, 1, &s->aes_encrypt_key); qemu_iovec_reset(&acb->hd_qiov); qemu_iovec_add(&acb->hd_qiov, acb->cluster_data, acb->cur_nr_sectors * 512); } BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO); acb->hd_aiocb = bdrv_aio_writev(bs->file, (acb->cluster_offset >> 9) + index_in_cluster, &acb->hd_qiov, acb->cur_nr_sectors, qcow2_aio_write_cb, acb); if (acb->hd_aiocb == NULL) { ret = -EIO; goto fail; } return; fail: if (acb->l2meta.nb_clusters != 0) { QLIST_REMOVE(&acb->l2meta, next_in_flight); } done: acb->common.cb(acb->common.opaque, ret); qemu_iovec_destroy(&acb->hd_qiov); qemu_aio_release(acb); } static BlockDriverAIOCB *qcow2_aio_writev(BlockDriverState *bs, int64_t sector_num, QEMUIOVector *qiov, int nb_sectors, BlockDriverCompletionFunc *cb, void *opaque) { BDRVQcowState *s = bs->opaque; QCowAIOCB *acb; s->cluster_cache_offset = -1; /* disable compressed cache */ acb = qcow2_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 1); if (!acb) return NULL; qcow2_aio_write_cb(acb, 0); return &acb->common; } static void qcow2_close(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; qemu_free(s->l1_table); qcow2_cache_flush(bs, s->l2_table_cache); qcow2_cache_flush(bs, s->refcount_block_cache); qcow2_cache_destroy(bs, s->l2_table_cache); qcow2_cache_destroy(bs, s->refcount_block_cache); qemu_free(s->cluster_cache); qemu_free(s->cluster_data); qcow2_refcount_close(bs); } /* * Updates the variable length parts of the qcow2 header, 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. */ static int qcow2_update_ext_header(BlockDriverState *bs, const char *backing_file, const char *backing_fmt) { size_t backing_file_len = 0; size_t backing_fmt_len = 0; BDRVQcowState *s = bs->opaque; QCowExtension ext_backing_fmt = {0, 0}; int ret; /* Backing file format doesn't make sense without a backing file */ if (backing_fmt && !backing_file) { return -EINVAL; } /* Prepare the backing file format extension if needed */ if (backing_fmt) { ext_backing_fmt.len = cpu_to_be32(strlen(backing_fmt)); ext_backing_fmt.magic = cpu_to_be32(QCOW2_EXT_MAGIC_BACKING_FORMAT); backing_fmt_len = ((sizeof(ext_backing_fmt) + strlen(backing_fmt) + 7) & ~7); } /* Check if we can fit the new header into the first cluster */ if (backing_file) { backing_file_len = strlen(backing_file); } size_t header_size = sizeof(QCowHeader) + backing_file_len + backing_fmt_len; if (header_size > s->cluster_size) { return -ENOSPC; } /* Rewrite backing file name and qcow2 extensions */ size_t ext_size = header_size - sizeof(QCowHeader); uint8_t buf[ext_size]; size_t offset = 0; size_t backing_file_offset = 0; if (backing_file) { if (backing_fmt) { int padding = backing_fmt_len - (sizeof(ext_backing_fmt) + strlen(backing_fmt)); memcpy(buf + offset, &ext_backing_fmt, sizeof(ext_backing_fmt)); offset += sizeof(ext_backing_fmt); memcpy(buf + offset, backing_fmt, strlen(backing_fmt)); offset += strlen(backing_fmt); memset(buf + offset, 0, padding); offset += padding; } memcpy(buf + offset, backing_file, backing_file_len); backing_file_offset = sizeof(QCowHeader) + offset; } ret = bdrv_pwrite_sync(bs->file, sizeof(QCowHeader), buf, ext_size); if (ret < 0) { goto fail; } /* Update header fields */ uint64_t be_backing_file_offset = cpu_to_be64(backing_file_offset); uint32_t be_backing_file_size = cpu_to_be32(backing_file_len); ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, backing_file_offset), &be_backing_file_offset, sizeof(uint64_t)); if (ret < 0) { goto fail; } ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, backing_file_size), &be_backing_file_size, sizeof(uint32_t)); if (ret < 0) { goto fail; } ret = 0; fail: return ret; } static int qcow2_change_backing_file(BlockDriverState *bs, const char *backing_file, const char *backing_fmt) { return qcow2_update_ext_header(bs, backing_file, backing_fmt); } static int preallocate(BlockDriverState *bs) { uint64_t nb_sectors; uint64_t offset; int num; int ret; QCowL2Meta meta; nb_sectors = bdrv_getlength(bs) >> 9; offset = 0; QLIST_INIT(&meta.dependent_requests); meta.cluster_offset = 0; while (nb_sectors) { num = MIN(nb_sectors, INT_MAX >> 9); ret = qcow2_alloc_cluster_offset(bs, offset, 0, num, &num, &meta); if (ret < 0) { return ret; } ret = qcow2_alloc_cluster_link_l2(bs, &meta); if (ret < 0) { qcow2_free_any_clusters(bs, meta.cluster_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 */ run_dependent_requests(&meta); /* 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 (meta.cluster_offset != 0) { uint8_t buf[512]; memset(buf, 0, 512); ret = bdrv_write(bs->file, (meta.cluster_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) { /* Calulate 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\n", 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(QCOW_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); if (flags & BLOCK_FLAG_ENCRYPT) { header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES); } else { header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE); } ret = bdrv_pwrite(bs, 0, &header, sizeof(header)); if (ret < 0) { goto out; } /* Write an empty refcount table */ refcount_table = qemu_mallocz(cluster_size); ret = bdrv_pwrite(bs, cluster_size, refcount_table, cluster_size); qemu_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) { ret = preallocate(bs); 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; /* 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; } } options++; } if (backing_file && prealloc) { fprintf(stderr, "Backing file and preallocation cannot be used at " "the same time\n"); return -EINVAL; } return qcow2_create2(filename, sectors, backing_file, backing_fmt, flags, cluster_size, prealloc, options); } 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 int qcow2_discard(BlockDriverState *bs, int64_t sector_num, int nb_sectors) { return qcow2_discard_clusters(bs, sector_num << BDRV_SECTOR_BITS, nb_sectors); } static int qcow2_truncate(BlockDriverState *bs, int64_t offset) { BDRVQcowState *s = bs->opaque; int ret, new_l1_size; if (offset & 511) { return -EINVAL; } /* cannot proceed if image has snapshots */ if (s->nb_snapshots) { return -ENOTSUP; } /* shrinking is currently not supported */ if (offset < bs->total_sectors * 512) { 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 = qemu_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) { qemu_free(out_buf); return -1; } 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) { qemu_free(out_buf); deflateEnd(&strm); return -1; } 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 */ bdrv_write(bs, sector_num, buf, s->cluster_sectors); } else { cluster_offset = qcow2_alloc_compressed_cluster_offset(bs, sector_num << 9, out_len); if (!cluster_offset) return -1; cluster_offset &= s->cluster_offset_mask; BLKDBG_EVENT(bs->file, BLKDBG_WRITE_COMPRESSED); if (bdrv_pwrite(bs->file, cluster_offset, out_buf, out_len) != out_len) { qemu_free(out_buf); return -1; } } qemu_free(out_buf); return 0; } static int qcow2_flush(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; int ret; ret = qcow2_cache_flush(bs, s->l2_table_cache); if (ret < 0) { return ret; } ret = qcow2_cache_flush(bs, s->refcount_block_cache); if (ret < 0) { return ret; } return bdrv_flush(bs->file); } static BlockDriverAIOCB *qcow2_aio_flush(BlockDriverState *bs, BlockDriverCompletionFunc *cb, void *opaque) { BDRVQcowState *s = bs->opaque; int ret; ret = qcow2_cache_flush(bs, s->l2_table_cache); if (ret < 0) { return NULL; } ret = qcow2_cache_flush(bs, s->refcount_block_cache); if (ret < 0) { return NULL; } return bdrv_aio_flush(bs->file, cb, opaque); } 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; } static int qcow2_check(BlockDriverState *bs, BdrvCheckResult *result) { return qcow2_check_refcounts(bs, result); } #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_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)" }, { 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_create = qcow2_create, .bdrv_flush = qcow2_flush, .bdrv_is_allocated = qcow2_is_allocated, .bdrv_set_key = qcow2_set_key, .bdrv_make_empty = qcow2_make_empty, .bdrv_aio_readv = qcow2_aio_readv, .bdrv_aio_writev = qcow2_aio_writev, .bdrv_aio_flush = qcow2_aio_flush, .bdrv_discard = qcow2_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, .create_options = qcow2_create_options, .bdrv_check = qcow2_check, }; static void bdrv_qcow2_init(void) { bdrv_register(&bdrv_qcow2); } block_init(bdrv_qcow2_init);