/* * 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 #include "aes.h" #include /* 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. */ //#define DEBUG_ALLOC //#define DEBUG_ALLOC2 #define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb) #define QCOW_VERSION 2 #define QCOW_CRYPT_NONE 0 #define QCOW_CRYPT_AES 1 /* indicate that the refcount of the referenced cluster is exactly one. */ #define QCOW_OFLAG_COPIED (1LL << 63) /* indicate that the cluster is compressed (they never have the copied flag) */ #define QCOW_OFLAG_COMPRESSED (1LL << 62) #define REFCOUNT_SHIFT 1 /* refcount size is 2 bytes */ #ifndef offsetof #define offsetof(type, field) ((size_t) &((type *)0)->field) #endif typedef struct QCowHeader { uint32_t magic; uint32_t version; uint64_t backing_file_offset; uint32_t backing_file_size; uint32_t cluster_bits; uint64_t size; /* in bytes */ uint32_t crypt_method; uint32_t l1_size; /* XXX: save number of clusters instead ? */ uint64_t l1_table_offset; uint64_t refcount_table_offset; uint32_t refcount_table_clusters; uint32_t nb_snapshots; uint64_t snapshots_offset; } QCowHeader; typedef struct __attribute__((packed)) QCowSnapshotHeader { /* header is 8 byte aligned */ uint64_t l1_table_offset; uint32_t l1_size; uint16_t id_str_size; uint16_t name_size; uint32_t date_sec; uint32_t date_nsec; uint64_t vm_clock_nsec; uint32_t vm_state_size; uint32_t extra_data_size; /* for extension */ /* extra data follows */ /* id_str follows */ /* name follows */ } QCowSnapshotHeader; #define L2_CACHE_SIZE 16 typedef struct QCowSnapshot { uint64_t l1_table_offset; uint32_t l1_size; char *id_str; char *name; uint32_t vm_state_size; uint32_t date_sec; uint32_t date_nsec; uint64_t vm_clock_nsec; } QCowSnapshot; typedef struct BDRVQcowState { BlockDriverState *hd; int cluster_bits; int cluster_size; int cluster_sectors; int l2_bits; int l2_size; int l1_size; int l1_vm_state_index; int csize_shift; int csize_mask; uint64_t cluster_offset_mask; uint64_t l1_table_offset; uint64_t *l1_table; uint64_t *l2_cache; uint64_t l2_cache_offsets[L2_CACHE_SIZE]; uint32_t l2_cache_counts[L2_CACHE_SIZE]; uint8_t *cluster_cache; uint8_t *cluster_data; uint64_t cluster_cache_offset; uint64_t *refcount_table; uint64_t refcount_table_offset; uint32_t refcount_table_size; uint64_t refcount_block_cache_offset; uint16_t *refcount_block_cache; int64_t free_cluster_index; int64_t free_byte_offset; uint32_t crypt_method; /* current crypt method, 0 if no key yet */ uint32_t crypt_method_header; AES_KEY aes_encrypt_key; AES_KEY aes_decrypt_key; uint64_t snapshots_offset; int snapshots_size; int nb_snapshots; QCowSnapshot *snapshots; } BDRVQcowState; static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset); static int qcow_read(BlockDriverState *bs, int64_t sector_num, uint8_t *buf, int nb_sectors); static int qcow_read_snapshots(BlockDriverState *bs); static void qcow_free_snapshots(BlockDriverState *bs); static int refcount_init(BlockDriverState *bs); static void refcount_close(BlockDriverState *bs); static int get_refcount(BlockDriverState *bs, int64_t cluster_index); static int update_cluster_refcount(BlockDriverState *bs, int64_t cluster_index, int addend); static void update_refcount(BlockDriverState *bs, int64_t offset, int64_t length, int addend); static int64_t alloc_clusters(BlockDriverState *bs, int64_t size); static int64_t alloc_bytes(BlockDriverState *bs, int size); static void free_clusters(BlockDriverState *bs, int64_t offset, int64_t size); #ifdef DEBUG_ALLOC static void check_refcounts(BlockDriverState *bs); #endif static int qcow_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; } static int qcow_open(BlockDriverState *bs, const char *filename, int flags) { BDRVQcowState *s = bs->opaque; int len, i, shift, ret; QCowHeader header; ret = bdrv_file_open(&s->hd, filename, flags); if (ret < 0) return ret; if (bdrv_pread(s->hd, 0, &header, sizeof(header)) != sizeof(header)) 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 || header.version != QCOW_VERSION) goto fail; if (header.size <= 1 || header.cluster_bits < 9 || header.cluster_bits > 16) goto fail; if (header.crypt_method > QCOW_CRYPT_AES) 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; shift = s->cluster_bits + s->l2_bits; s->l1_vm_state_index = (header.size + (1LL << shift) - 1) >> shift; /* the L1 table must contain at least enough entries to put header.size bytes */ if (s->l1_size < s->l1_vm_state_index) goto fail; s->l1_table_offset = header.l1_table_offset; s->l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t)); if (!s->l1_table) goto fail; if (bdrv_pread(s->hd, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)) != s->l1_size * sizeof(uint64_t)) goto fail; for(i = 0;i < s->l1_size; i++) { be64_to_cpus(&s->l1_table[i]); } /* alloc L2 cache */ s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t)); if (!s->l2_cache) goto fail; s->cluster_cache = qemu_malloc(s->cluster_size); if (!s->cluster_cache) goto fail; /* one more sector for decompressed data alignment */ s->cluster_data = qemu_malloc(s->cluster_size + 512); if (!s->cluster_data) goto fail; s->cluster_cache_offset = -1; if (refcount_init(bs) < 0) goto fail; /* read the backing file name */ if (header.backing_file_offset != 0) { len = header.backing_file_size; if (len > 1023) len = 1023; if (bdrv_pread(s->hd, header.backing_file_offset, bs->backing_file, len) != len) goto fail; bs->backing_file[len] = '\0'; } if (qcow_read_snapshots(bs) < 0) goto fail; #ifdef DEBUG_ALLOC check_refcounts(bs); #endif return 0; fail: qcow_free_snapshots(bs); refcount_close(bs); qemu_free(s->l1_table); qemu_free(s->l2_cache); qemu_free(s->cluster_cache); qemu_free(s->cluster_data); bdrv_delete(s->hd); return -1; } static int qcow_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; } /* The crypt function is compatible with the linux cryptoloop algorithm for < 4 GB images. NOTE: out_buf == in_buf is supported */ static void encrypt_sectors(BDRVQcowState *s, int64_t sector_num, uint8_t *out_buf, const uint8_t *in_buf, int nb_sectors, int enc, const AES_KEY *key) { union { uint64_t ll[2]; uint8_t b[16]; } ivec; int i; for(i = 0; i < nb_sectors; i++) { ivec.ll[0] = cpu_to_le64(sector_num); ivec.ll[1] = 0; AES_cbc_encrypt(in_buf, out_buf, 512, key, ivec.b, enc); sector_num++; in_buf += 512; out_buf += 512; } } static int copy_sectors(BlockDriverState *bs, uint64_t start_sect, uint64_t cluster_offset, int n_start, int n_end) { BDRVQcowState *s = bs->opaque; int n, ret; n = n_end - n_start; if (n <= 0) return 0; ret = qcow_read(bs, start_sect + n_start, s->cluster_data, n); if (ret < 0) return ret; if (s->crypt_method) { encrypt_sectors(s, start_sect + n_start, s->cluster_data, s->cluster_data, n, 1, &s->aes_encrypt_key); } ret = bdrv_write(s->hd, (cluster_offset >> 9) + n_start, s->cluster_data, n); if (ret < 0) return ret; return 0; } static void l2_cache_reset(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t)); memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t)); memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t)); } static inline int l2_cache_new_entry(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; uint32_t min_count; int min_index, i; /* find a new entry in the least used one */ min_index = 0; min_count = 0xffffffff; for(i = 0; i < L2_CACHE_SIZE; i++) { if (s->l2_cache_counts[i] < min_count) { min_count = s->l2_cache_counts[i]; min_index = i; } } return min_index; } static int64_t align_offset(int64_t offset, int n) { offset = (offset + n - 1) & ~(n - 1); return offset; } static int grow_l1_table(BlockDriverState *bs, int min_size) { BDRVQcowState *s = bs->opaque; int new_l1_size, new_l1_size2, ret, i; uint64_t *new_l1_table; uint64_t new_l1_table_offset; uint64_t data64; uint32_t data32; new_l1_size = s->l1_size; if (min_size <= new_l1_size) return 0; while (min_size > new_l1_size) { new_l1_size = (new_l1_size * 3 + 1) / 2; } #ifdef DEBUG_ALLOC2 printf("grow l1_table from %d to %d\n", s->l1_size, new_l1_size); #endif new_l1_size2 = sizeof(uint64_t) * new_l1_size; new_l1_table = qemu_mallocz(new_l1_size2); if (!new_l1_table) return -ENOMEM; memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t)); /* write new table (align to cluster) */ new_l1_table_offset = alloc_clusters(bs, new_l1_size2); for(i = 0; i < s->l1_size; i++) new_l1_table[i] = cpu_to_be64(new_l1_table[i]); ret = bdrv_pwrite(s->hd, new_l1_table_offset, new_l1_table, new_l1_size2); if (ret != new_l1_size2) goto fail; for(i = 0; i < s->l1_size; i++) new_l1_table[i] = be64_to_cpu(new_l1_table[i]); /* set new table */ data64 = cpu_to_be64(new_l1_table_offset); if (bdrv_pwrite(s->hd, offsetof(QCowHeader, l1_table_offset), &data64, sizeof(data64)) != sizeof(data64)) goto fail; data32 = cpu_to_be32(new_l1_size); if (bdrv_pwrite(s->hd, offsetof(QCowHeader, l1_size), &data32, sizeof(data32)) != sizeof(data32)) goto fail; qemu_free(s->l1_table); free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t)); s->l1_table_offset = new_l1_table_offset; s->l1_table = new_l1_table; s->l1_size = new_l1_size; return 0; fail: qemu_free(s->l1_table); return -EIO; } /* * seek_l2_table * * seek l2_offset in the l2_cache table * if not found, return NULL, * if found, * increments the l2 cache hit count of the entry, * if counter overflow, divide by two all counters * return the pointer to the l2 cache entry * */ static uint64_t *seek_l2_table(BDRVQcowState *s, uint64_t l2_offset) { int i, j; for(i = 0; i < L2_CACHE_SIZE; i++) { if (l2_offset == s->l2_cache_offsets[i]) { /* increment the hit count */ if (++s->l2_cache_counts[i] == 0xffffffff) { for(j = 0; j < L2_CACHE_SIZE; j++) { s->l2_cache_counts[j] >>= 1; } } return s->l2_cache + (i << s->l2_bits); } } return NULL; } /* * l2_load * * Loads a L2 table into memory. If the table is in the cache, the cache * is used; otherwise the L2 table is loaded from the image file. * * Returns a pointer to the L2 table on success, or NULL if the read from * the image file failed. */ static uint64_t *l2_load(BlockDriverState *bs, uint64_t l2_offset) { BDRVQcowState *s = bs->opaque; int min_index; uint64_t *l2_table; /* seek if the table for the given offset is in the cache */ l2_table = seek_l2_table(s, l2_offset); if (l2_table != NULL) return l2_table; /* not found: load a new entry in the least used one */ min_index = l2_cache_new_entry(bs); l2_table = s->l2_cache + (min_index << s->l2_bits); if (bdrv_pread(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) != s->l2_size * sizeof(uint64_t)) return NULL; s->l2_cache_offsets[min_index] = l2_offset; s->l2_cache_counts[min_index] = 1; return l2_table; } /* * l2_allocate * * Allocate a new l2 entry in the file. If l1_index points to an already * used entry in the L2 table (i.e. we are doing a copy on write for the L2 * table) copy the contents of the old L2 table into the newly allocated one. * Otherwise the new table is initialized with zeros. * */ static uint64_t *l2_allocate(BlockDriverState *bs, int l1_index) { BDRVQcowState *s = bs->opaque; int min_index; uint64_t old_l2_offset, tmp; uint64_t *l2_table, l2_offset; old_l2_offset = s->l1_table[l1_index]; /* allocate a new l2 entry */ l2_offset = alloc_clusters(bs, s->l2_size * sizeof(uint64_t)); /* update the L1 entry */ s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED; tmp = cpu_to_be64(l2_offset | QCOW_OFLAG_COPIED); if (bdrv_pwrite(s->hd, s->l1_table_offset + l1_index * sizeof(tmp), &tmp, sizeof(tmp)) != sizeof(tmp)) return NULL; /* allocate a new entry in the l2 cache */ min_index = l2_cache_new_entry(bs); l2_table = s->l2_cache + (min_index << s->l2_bits); if (old_l2_offset == 0) { /* if there was no old l2 table, clear the new table */ memset(l2_table, 0, s->l2_size * sizeof(uint64_t)); } else { /* if there was an old l2 table, read it from the disk */ if (bdrv_pread(s->hd, old_l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) != s->l2_size * sizeof(uint64_t)) return NULL; } /* write the l2 table to the file */ if (bdrv_pwrite(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) != s->l2_size * sizeof(uint64_t)) return NULL; /* update the l2 cache entry */ s->l2_cache_offsets[min_index] = l2_offset; s->l2_cache_counts[min_index] = 1; return l2_table; } /* * get_cluster_offset * * For a given offset of the disk image, return cluster offset in * qcow2 file. * * Return 1, if the offset is found * Return 0, otherwise. * */ static uint64_t get_cluster_offset(BlockDriverState *bs, uint64_t offset) { BDRVQcowState *s = bs->opaque; int l1_index, l2_index; uint64_t l2_offset, *l2_table, cluster_offset; /* seek the the l2 offset in the l1 table */ l1_index = offset >> (s->l2_bits + s->cluster_bits); if (l1_index >= s->l1_size) return 0; l2_offset = s->l1_table[l1_index]; /* seek the l2 table of the given l2 offset */ if (!l2_offset) return 0; /* load the l2 table in memory */ l2_offset &= ~QCOW_OFLAG_COPIED; l2_table = l2_load(bs, l2_offset); if (l2_table == NULL) return 0; /* find the cluster offset for the given disk offset */ l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1); cluster_offset = be64_to_cpu(l2_table[l2_index]); return cluster_offset & ~QCOW_OFLAG_COPIED; } /* * alloc_cluster_offset * * For a given offset of the disk image, return cluster offset in * qcow2 file. * * If the offset is not found, allocate a new cluster. * * Return the cluster offset if successful, * Return 0, otherwise. * */ static uint64_t alloc_cluster_offset(BlockDriverState *bs, uint64_t offset, int compressed_size, int n_start, int n_end) { BDRVQcowState *s = bs->opaque; int l1_index, l2_index, ret; uint64_t l2_offset, *l2_table, cluster_offset; /* seek the the l2 offset in the l1 table */ l1_index = offset >> (s->l2_bits + s->cluster_bits); if (l1_index >= s->l1_size) { ret = grow_l1_table(bs, l1_index + 1); if (ret < 0) return 0; } l2_offset = s->l1_table[l1_index]; /* seek the l2 table of the given l2 offset */ if (l2_offset & QCOW_OFLAG_COPIED) { /* load the l2 table in memory */ l2_offset &= ~QCOW_OFLAG_COPIED; l2_table = l2_load(bs, l2_offset); if (l2_table == NULL) return 0; } else { if (l2_offset) free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t)); l2_table = l2_allocate(bs, l1_index); if (l2_table == NULL) return 0; l2_offset = s->l1_table[l1_index] & ~QCOW_OFLAG_COPIED; } /* find the cluster offset for the given disk offset */ l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1); cluster_offset = be64_to_cpu(l2_table[l2_index]); if (cluster_offset & QCOW_OFLAG_COPIED) return cluster_offset & ~QCOW_OFLAG_COPIED; if (cluster_offset) { /* free the cluster */ if (cluster_offset & QCOW_OFLAG_COMPRESSED) { int nb_csectors; nb_csectors = ((cluster_offset >> s->csize_shift) & s->csize_mask) + 1; free_clusters(bs, (cluster_offset & s->cluster_offset_mask) & ~511, nb_csectors * 512); } else { free_clusters(bs, cluster_offset, s->cluster_size); } } if (compressed_size) { int nb_csectors; cluster_offset = alloc_bytes(bs, compressed_size); nb_csectors = ((cluster_offset + compressed_size - 1) >> 9) - (cluster_offset >> 9); cluster_offset |= QCOW_OFLAG_COMPRESSED | ((uint64_t)nb_csectors << s->csize_shift); /* update L2 table */ /* compressed clusters never have the copied flag */ l2_table[l2_index] = cpu_to_be64(cluster_offset); if (bdrv_pwrite(s->hd, l2_offset + l2_index * sizeof(uint64_t), l2_table + l2_index, sizeof(uint64_t)) != sizeof(uint64_t)) return 0; return cluster_offset; } /* allocate a new cluster */ cluster_offset = alloc_clusters(bs, s->cluster_size); /* we must initialize the cluster content which won't be written */ if ((n_end - n_start) < s->cluster_sectors) { uint64_t start_sect; start_sect = (offset & ~(s->cluster_size - 1)) >> 9; ret = copy_sectors(bs, start_sect, cluster_offset, 0, n_start); if (ret < 0) return 0; ret = copy_sectors(bs, start_sect, cluster_offset, n_end, s->cluster_sectors); if (ret < 0) return 0; } /* update L2 table */ l2_table[l2_index] = cpu_to_be64(cluster_offset | QCOW_OFLAG_COPIED); if (bdrv_pwrite(s->hd, l2_offset + l2_index * sizeof(uint64_t), l2_table + l2_index, sizeof(uint64_t)) != sizeof(uint64_t)) return 0; return cluster_offset; } static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors, int *pnum) { BDRVQcowState *s = bs->opaque; int index_in_cluster, n; uint64_t cluster_offset; cluster_offset = get_cluster_offset(bs, sector_num << 9); index_in_cluster = sector_num & (s->cluster_sectors - 1); n = s->cluster_sectors - index_in_cluster; if (n > nb_sectors) n = nb_sectors; *pnum = n; return (cluster_offset != 0); } static int decompress_buffer(uint8_t *out_buf, int out_buf_size, const uint8_t *buf, int buf_size) { z_stream strm1, *strm = &strm1; int ret, out_len; memset(strm, 0, sizeof(*strm)); strm->next_in = (uint8_t *)buf; strm->avail_in = buf_size; strm->next_out = out_buf; strm->avail_out = out_buf_size; ret = inflateInit2(strm, -12); if (ret != Z_OK) return -1; ret = inflate(strm, Z_FINISH); out_len = strm->next_out - out_buf; if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) || out_len != out_buf_size) { inflateEnd(strm); return -1; } inflateEnd(strm); return 0; } static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset) { int ret, csize, nb_csectors, sector_offset; uint64_t coffset; coffset = cluster_offset & s->cluster_offset_mask; if (s->cluster_cache_offset != coffset) { nb_csectors = ((cluster_offset >> s->csize_shift) & s->csize_mask) + 1; sector_offset = coffset & 511; csize = nb_csectors * 512 - sector_offset; ret = bdrv_read(s->hd, coffset >> 9, s->cluster_data, nb_csectors); if (ret < 0) { return -1; } if (decompress_buffer(s->cluster_cache, s->cluster_size, s->cluster_data + sector_offset, csize) < 0) { return -1; } s->cluster_cache_offset = coffset; } return 0; } /* handle reading after the end of the backing file */ static int backing_read1(BlockDriverState *bs, int64_t sector_num, uint8_t *buf, 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; memset(buf + n1 * 512, 0, 512 * (nb_sectors - n1)); return n1; } static int qcow_read(BlockDriverState *bs, int64_t sector_num, uint8_t *buf, int nb_sectors) { BDRVQcowState *s = bs->opaque; int ret, index_in_cluster, n, n1; uint64_t cluster_offset; while (nb_sectors > 0) { cluster_offset = get_cluster_offset(bs, sector_num << 9); index_in_cluster = sector_num & (s->cluster_sectors - 1); n = s->cluster_sectors - index_in_cluster; if (n > nb_sectors) n = nb_sectors; if (!cluster_offset) { if (bs->backing_hd) { /* read from the base image */ n1 = backing_read1(bs->backing_hd, sector_num, buf, n); if (n1 > 0) { ret = bdrv_read(bs->backing_hd, sector_num, buf, n1); if (ret < 0) return -1; } } else { memset(buf, 0, 512 * n); } } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) { if (decompress_cluster(s, cluster_offset) < 0) return -1; memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n); } else { ret = bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512); if (ret != n * 512) return -1; if (s->crypt_method) { encrypt_sectors(s, sector_num, buf, buf, n, 0, &s->aes_decrypt_key); } } nb_sectors -= n; sector_num += n; buf += n * 512; } return 0; } static int qcow_write(BlockDriverState *bs, int64_t sector_num, const uint8_t *buf, int nb_sectors) { BDRVQcowState *s = bs->opaque; int ret, index_in_cluster, n; uint64_t cluster_offset; while (nb_sectors > 0) { index_in_cluster = sector_num & (s->cluster_sectors - 1); n = s->cluster_sectors - index_in_cluster; if (n > nb_sectors) n = nb_sectors; cluster_offset = alloc_cluster_offset(bs, sector_num << 9, 0, index_in_cluster, index_in_cluster + n); if (!cluster_offset) return -1; if (s->crypt_method) { encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1, &s->aes_encrypt_key); ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, s->cluster_data, n * 512); } else { ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512); } if (ret != n * 512) return -1; nb_sectors -= n; sector_num += n; buf += n * 512; } s->cluster_cache_offset = -1; /* disable compressed cache */ return 0; } typedef struct QCowAIOCB { BlockDriverAIOCB common; int64_t sector_num; uint8_t *buf; int nb_sectors; int n; uint64_t cluster_offset; uint8_t *cluster_data; BlockDriverAIOCB *hd_aiocb; } QCowAIOCB; static void qcow_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) { fail: acb->common.cb(acb->common.opaque, ret); qemu_aio_release(acb); return; } redo: /* 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) { encrypt_sectors(s, acb->sector_num, acb->buf, acb->buf, acb->n, 0, &s->aes_decrypt_key); } } acb->nb_sectors -= acb->n; acb->sector_num += acb->n; acb->buf += acb->n * 512; if (acb->nb_sectors == 0) { /* request completed */ acb->common.cb(acb->common.opaque, 0); qemu_aio_release(acb); return; } /* prepare next AIO request */ acb->cluster_offset = get_cluster_offset(bs, acb->sector_num << 9); index_in_cluster = acb->sector_num & (s->cluster_sectors - 1); acb->n = s->cluster_sectors - index_in_cluster; if (acb->n > acb->nb_sectors) acb->n = acb->nb_sectors; if (!acb->cluster_offset) { if (bs->backing_hd) { /* read from the base image */ n1 = backing_read1(bs->backing_hd, acb->sector_num, acb->buf, acb->n); if (n1 > 0) { acb->hd_aiocb = bdrv_aio_read(bs->backing_hd, acb->sector_num, acb->buf, acb->n, qcow_aio_read_cb, acb); if (acb->hd_aiocb == NULL) goto fail; } else { goto redo; } } else { /* Note: in this case, no need to wait */ memset(acb->buf, 0, 512 * acb->n); goto redo; } } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) { /* add AIO support for compressed blocks ? */ if (decompress_cluster(s, acb->cluster_offset) < 0) goto fail; memcpy(acb->buf, s->cluster_cache + index_in_cluster * 512, 512 * acb->n); goto redo; } else { if ((acb->cluster_offset & 511) != 0) { ret = -EIO; goto fail; } acb->hd_aiocb = bdrv_aio_read(s->hd, (acb->cluster_offset >> 9) + index_in_cluster, acb->buf, acb->n, qcow_aio_read_cb, acb); if (acb->hd_aiocb == NULL) goto fail; } } static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs, int64_t sector_num, uint8_t *buf, int nb_sectors, BlockDriverCompletionFunc *cb, void *opaque) { QCowAIOCB *acb; acb = qemu_aio_get(bs, cb, opaque); if (!acb) return NULL; acb->hd_aiocb = NULL; acb->sector_num = sector_num; acb->buf = buf; acb->nb_sectors = nb_sectors; acb->n = 0; acb->cluster_offset = 0; return acb; } static BlockDriverAIOCB *qcow_aio_read(BlockDriverState *bs, int64_t sector_num, uint8_t *buf, int nb_sectors, BlockDriverCompletionFunc *cb, void *opaque) { QCowAIOCB *acb; acb = qcow_aio_setup(bs, sector_num, buf, nb_sectors, cb, opaque); if (!acb) return NULL; qcow_aio_read_cb(acb, 0); return &acb->common; } static void qcow_aio_write_cb(void *opaque, int ret) { QCowAIOCB *acb = opaque; BlockDriverState *bs = acb->common.bs; BDRVQcowState *s = bs->opaque; int index_in_cluster; uint64_t cluster_offset; const uint8_t *src_buf; acb->hd_aiocb = NULL; if (ret < 0) { fail: acb->common.cb(acb->common.opaque, ret); qemu_aio_release(acb); return; } acb->nb_sectors -= acb->n; acb->sector_num += acb->n; acb->buf += acb->n * 512; if (acb->nb_sectors == 0) { /* request completed */ acb->common.cb(acb->common.opaque, 0); qemu_aio_release(acb); return; } index_in_cluster = acb->sector_num & (s->cluster_sectors - 1); acb->n = s->cluster_sectors - index_in_cluster; if (acb->n > acb->nb_sectors) acb->n = acb->nb_sectors; cluster_offset = alloc_cluster_offset(bs, acb->sector_num << 9, 0, index_in_cluster, index_in_cluster + acb->n); if (!cluster_offset || (cluster_offset & 511) != 0) { ret = -EIO; goto fail; } if (s->crypt_method) { if (!acb->cluster_data) { acb->cluster_data = qemu_mallocz(s->cluster_size); if (!acb->cluster_data) { ret = -ENOMEM; goto fail; } } encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->buf, acb->n, 1, &s->aes_encrypt_key); src_buf = acb->cluster_data; } else { src_buf = acb->buf; } acb->hd_aiocb = bdrv_aio_write(s->hd, (cluster_offset >> 9) + index_in_cluster, src_buf, acb->n, qcow_aio_write_cb, acb); if (acb->hd_aiocb == NULL) goto fail; } static BlockDriverAIOCB *qcow_aio_write(BlockDriverState *bs, int64_t sector_num, const uint8_t *buf, int nb_sectors, BlockDriverCompletionFunc *cb, void *opaque) { BDRVQcowState *s = bs->opaque; QCowAIOCB *acb; s->cluster_cache_offset = -1; /* disable compressed cache */ acb = qcow_aio_setup(bs, sector_num, (uint8_t*)buf, nb_sectors, cb, opaque); if (!acb) return NULL; qcow_aio_write_cb(acb, 0); return &acb->common; } static void qcow_aio_cancel(BlockDriverAIOCB *blockacb) { QCowAIOCB *acb = (QCowAIOCB *)blockacb; if (acb->hd_aiocb) bdrv_aio_cancel(acb->hd_aiocb); qemu_aio_release(acb); } static void qcow_close(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; qemu_free(s->l1_table); qemu_free(s->l2_cache); qemu_free(s->cluster_cache); qemu_free(s->cluster_data); refcount_close(bs); bdrv_delete(s->hd); } /* XXX: use std qcow open function ? */ typedef struct QCowCreateState { int cluster_size; int cluster_bits; uint16_t *refcount_block; uint64_t *refcount_table; int64_t l1_table_offset; int64_t refcount_table_offset; int64_t refcount_block_offset; } QCowCreateState; static void create_refcount_update(QCowCreateState *s, int64_t offset, int64_t size) { int refcount; int64_t start, last, cluster_offset; uint16_t *p; start = offset & ~(s->cluster_size - 1); last = (offset + size - 1) & ~(s->cluster_size - 1); for(cluster_offset = start; cluster_offset <= last; cluster_offset += s->cluster_size) { p = &s->refcount_block[cluster_offset >> s->cluster_bits]; refcount = be16_to_cpu(*p); refcount++; *p = cpu_to_be16(refcount); } } static int qcow_create(const char *filename, int64_t total_size, const char *backing_file, int flags) { int fd, header_size, backing_filename_len, l1_size, i, shift, l2_bits; QCowHeader header; uint64_t tmp, offset; QCowCreateState s1, *s = &s1; memset(s, 0, sizeof(*s)); fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644); if (fd < 0) return -1; memset(&header, 0, sizeof(header)); header.magic = cpu_to_be32(QCOW_MAGIC); header.version = cpu_to_be32(QCOW_VERSION); header.size = cpu_to_be64(total_size * 512); header_size = sizeof(header); backing_filename_len = 0; if (backing_file) { header.backing_file_offset = cpu_to_be64(header_size); backing_filename_len = strlen(backing_file); header.backing_file_size = cpu_to_be32(backing_filename_len); header_size += backing_filename_len; } s->cluster_bits = 12; /* 4 KB clusters */ s->cluster_size = 1 << s->cluster_bits; header.cluster_bits = cpu_to_be32(s->cluster_bits); header_size = (header_size + 7) & ~7; if (flags & BLOCK_FLAG_ENCRYPT) { header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES); } else { header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE); } l2_bits = s->cluster_bits - 3; shift = s->cluster_bits + l2_bits; l1_size = (((total_size * 512) + (1LL << shift) - 1) >> shift); offset = align_offset(header_size, s->cluster_size); s->l1_table_offset = offset; header.l1_table_offset = cpu_to_be64(s->l1_table_offset); header.l1_size = cpu_to_be32(l1_size); offset += align_offset(l1_size * sizeof(uint64_t), s->cluster_size); s->refcount_table = qemu_mallocz(s->cluster_size); if (!s->refcount_table) goto fail; s->refcount_block = qemu_mallocz(s->cluster_size); if (!s->refcount_block) goto fail; s->refcount_table_offset = offset; header.refcount_table_offset = cpu_to_be64(offset); header.refcount_table_clusters = cpu_to_be32(1); offset += s->cluster_size; s->refcount_table[0] = cpu_to_be64(offset); s->refcount_block_offset = offset; offset += s->cluster_size; /* update refcounts */ create_refcount_update(s, 0, header_size); create_refcount_update(s, s->l1_table_offset, l1_size * sizeof(uint64_t)); create_refcount_update(s, s->refcount_table_offset, s->cluster_size); create_refcount_update(s, s->refcount_block_offset, s->cluster_size); /* write all the data */ write(fd, &header, sizeof(header)); if (backing_file) { write(fd, backing_file, backing_filename_len); } lseek(fd, s->l1_table_offset, SEEK_SET); tmp = 0; for(i = 0;i < l1_size; i++) { write(fd, &tmp, sizeof(tmp)); } lseek(fd, s->refcount_table_offset, SEEK_SET); write(fd, s->refcount_table, s->cluster_size); lseek(fd, s->refcount_block_offset, SEEK_SET); write(fd, s->refcount_block, s->cluster_size); qemu_free(s->refcount_table); qemu_free(s->refcount_block); close(fd); return 0; fail: qemu_free(s->refcount_table); qemu_free(s->refcount_block); close(fd); return -ENOMEM; } static int qcow_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(s->hd, s->l1_table_offset, s->l1_table, l1_length) < 0) return -1; ret = bdrv_truncate(s->hd, s->l1_table_offset + l1_length); if (ret < 0) return ret; l2_cache_reset(bs); #endif return 0; } /* XXX: put compressed sectors first, then all the cluster aligned tables to avoid losing bytes in alignment */ static int qcow_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(s->hd); cluster_offset = (cluster_offset + 511) & ~511; bdrv_truncate(s->hd, cluster_offset); return 0; } if (nb_sectors != s->cluster_sectors) return -EINVAL; out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128); if (!out_buf) return -ENOMEM; /* 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 */ qcow_write(bs, sector_num, buf, s->cluster_sectors); } else { cluster_offset = alloc_cluster_offset(bs, sector_num << 9, out_len, 0, 0); cluster_offset &= s->cluster_offset_mask; if (bdrv_pwrite(s->hd, cluster_offset, out_buf, out_len) != out_len) { qemu_free(out_buf); return -1; } } qemu_free(out_buf); return 0; } static void qcow_flush(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; bdrv_flush(s->hd); } static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) { BDRVQcowState *s = bs->opaque; bdi->cluster_size = s->cluster_size; bdi->vm_state_offset = (int64_t)s->l1_vm_state_index << (s->cluster_bits + s->l2_bits); return 0; } /*********************************************************/ /* snapshot support */ /* update the refcounts of snapshots and the copied flag */ static int update_snapshot_refcount(BlockDriverState *bs, int64_t l1_table_offset, int l1_size, int addend) { BDRVQcowState *s = bs->opaque; uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated; int64_t old_offset, old_l2_offset; int l2_size, i, j, l1_modified, l2_modified, nb_csectors, refcount; l2_cache_reset(bs); l2_table = NULL; l1_table = NULL; l1_size2 = l1_size * sizeof(uint64_t); l1_allocated = 0; if (l1_table_offset != s->l1_table_offset) { l1_table = qemu_malloc(l1_size2); if (!l1_table) goto fail; l1_allocated = 1; if (bdrv_pread(s->hd, l1_table_offset, l1_table, l1_size2) != l1_size2) goto fail; for(i = 0;i < l1_size; i++) be64_to_cpus(&l1_table[i]); } else { assert(l1_size == s->l1_size); l1_table = s->l1_table; l1_allocated = 0; } l2_size = s->l2_size * sizeof(uint64_t); l2_table = qemu_malloc(l2_size); if (!l2_table) goto fail; l1_modified = 0; for(i = 0; i < l1_size; i++) { l2_offset = l1_table[i]; if (l2_offset) { old_l2_offset = l2_offset; l2_offset &= ~QCOW_OFLAG_COPIED; l2_modified = 0; if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size) goto fail; for(j = 0; j < s->l2_size; j++) { offset = be64_to_cpu(l2_table[j]); if (offset != 0) { old_offset = offset; offset &= ~QCOW_OFLAG_COPIED; if (offset & QCOW_OFLAG_COMPRESSED) { nb_csectors = ((offset >> s->csize_shift) & s->csize_mask) + 1; if (addend != 0) update_refcount(bs, (offset & s->cluster_offset_mask) & ~511, nb_csectors * 512, addend); /* compressed clusters are never modified */ refcount = 2; } else { if (addend != 0) { refcount = update_cluster_refcount(bs, offset >> s->cluster_bits, addend); } else { refcount = get_refcount(bs, offset >> s->cluster_bits); } } if (refcount == 1) { offset |= QCOW_OFLAG_COPIED; } if (offset != old_offset) { l2_table[j] = cpu_to_be64(offset); l2_modified = 1; } } } if (l2_modified) { if (bdrv_pwrite(s->hd, l2_offset, l2_table, l2_size) != l2_size) goto fail; } if (addend != 0) { refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend); } else { refcount = get_refcount(bs, l2_offset >> s->cluster_bits); } if (refcount == 1) { l2_offset |= QCOW_OFLAG_COPIED; } if (l2_offset != old_l2_offset) { l1_table[i] = l2_offset; l1_modified = 1; } } } if (l1_modified) { for(i = 0; i < l1_size; i++) cpu_to_be64s(&l1_table[i]); if (bdrv_pwrite(s->hd, l1_table_offset, l1_table, l1_size2) != l1_size2) goto fail; for(i = 0; i < l1_size; i++) be64_to_cpus(&l1_table[i]); } if (l1_allocated) qemu_free(l1_table); qemu_free(l2_table); return 0; fail: if (l1_allocated) qemu_free(l1_table); qemu_free(l2_table); return -EIO; } static void qcow_free_snapshots(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; int i; for(i = 0; i < s->nb_snapshots; i++) { qemu_free(s->snapshots[i].name); qemu_free(s->snapshots[i].id_str); } qemu_free(s->snapshots); s->snapshots = NULL; s->nb_snapshots = 0; } static int qcow_read_snapshots(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; QCowSnapshotHeader h; QCowSnapshot *sn; int i, id_str_size, name_size; int64_t offset; uint32_t extra_data_size; offset = s->snapshots_offset; s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot)); if (!s->snapshots) goto fail; for(i = 0; i < s->nb_snapshots; i++) { offset = align_offset(offset, 8); if (bdrv_pread(s->hd, offset, &h, sizeof(h)) != sizeof(h)) goto fail; offset += sizeof(h); sn = s->snapshots + i; sn->l1_table_offset = be64_to_cpu(h.l1_table_offset); sn->l1_size = be32_to_cpu(h.l1_size); sn->vm_state_size = be32_to_cpu(h.vm_state_size); sn->date_sec = be32_to_cpu(h.date_sec); sn->date_nsec = be32_to_cpu(h.date_nsec); sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec); extra_data_size = be32_to_cpu(h.extra_data_size); id_str_size = be16_to_cpu(h.id_str_size); name_size = be16_to_cpu(h.name_size); offset += extra_data_size; sn->id_str = qemu_malloc(id_str_size + 1); if (!sn->id_str) goto fail; if (bdrv_pread(s->hd, offset, sn->id_str, id_str_size) != id_str_size) goto fail; offset += id_str_size; sn->id_str[id_str_size] = '\0'; sn->name = qemu_malloc(name_size + 1); if (!sn->name) goto fail; if (bdrv_pread(s->hd, offset, sn->name, name_size) != name_size) goto fail; offset += name_size; sn->name[name_size] = '\0'; } s->snapshots_size = offset - s->snapshots_offset; return 0; fail: qcow_free_snapshots(bs); return -1; } /* add at the end of the file a new list of snapshots */ static int qcow_write_snapshots(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; QCowSnapshot *sn; QCowSnapshotHeader h; int i, name_size, id_str_size, snapshots_size; uint64_t data64; uint32_t data32; int64_t offset, snapshots_offset; /* 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 += strlen(sn->id_str); offset += strlen(sn->name); } snapshots_size = offset; snapshots_offset = alloc_clusters(bs, snapshots_size); offset = snapshots_offset; 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); 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); 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); if (bdrv_pwrite(s->hd, offset, &h, sizeof(h)) != sizeof(h)) goto fail; offset += sizeof(h); if (bdrv_pwrite(s->hd, offset, sn->id_str, id_str_size) != id_str_size) goto fail; offset += id_str_size; if (bdrv_pwrite(s->hd, offset, sn->name, name_size) != name_size) goto fail; offset += name_size; } /* update the various header fields */ data64 = cpu_to_be64(snapshots_offset); if (bdrv_pwrite(s->hd, offsetof(QCowHeader, snapshots_offset), &data64, sizeof(data64)) != sizeof(data64)) goto fail; data32 = cpu_to_be32(s->nb_snapshots); if (bdrv_pwrite(s->hd, offsetof(QCowHeader, nb_snapshots), &data32, sizeof(data32)) != sizeof(data32)) goto fail; /* free the old snapshot table */ free_clusters(bs, s->snapshots_offset, s->snapshots_size); s->snapshots_offset = snapshots_offset; s->snapshots_size = snapshots_size; return 0; fail: return -1; } static void find_new_snapshot_id(BlockDriverState *bs, char *id_str, int id_str_size) { BDRVQcowState *s = bs->opaque; QCowSnapshot *sn; int i, id, id_max = 0; for(i = 0; i < s->nb_snapshots; i++) { sn = s->snapshots + i; id = strtoul(sn->id_str, NULL, 10); if (id > id_max) id_max = id; } snprintf(id_str, id_str_size, "%d", id_max + 1); } static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str) { BDRVQcowState *s = bs->opaque; int i; for(i = 0; i < s->nb_snapshots; i++) { if (!strcmp(s->snapshots[i].id_str, id_str)) return i; } return -1; } static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name) { BDRVQcowState *s = bs->opaque; int i, ret; ret = find_snapshot_by_id(bs, name); if (ret >= 0) return ret; for(i = 0; i < s->nb_snapshots; i++) { if (!strcmp(s->snapshots[i].name, name)) return i; } return -1; } /* if no id is provided, a new one is constructed */ static int qcow_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info) { BDRVQcowState *s = bs->opaque; QCowSnapshot *snapshots1, sn1, *sn = &sn1; int i, ret; uint64_t *l1_table = NULL; memset(sn, 0, sizeof(*sn)); if (sn_info->id_str[0] == '\0') { /* compute a new id */ find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str)); } /* check that the ID is unique */ if (find_snapshot_by_id(bs, sn_info->id_str) >= 0) return -ENOENT; sn->id_str = qemu_strdup(sn_info->id_str); if (!sn->id_str) goto fail; sn->name = qemu_strdup(sn_info->name); if (!sn->name) goto fail; sn->vm_state_size = sn_info->vm_state_size; sn->date_sec = sn_info->date_sec; sn->date_nsec = sn_info->date_nsec; sn->vm_clock_nsec = sn_info->vm_clock_nsec; ret = update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1); if (ret < 0) goto fail; /* create the L1 table of the snapshot */ sn->l1_table_offset = alloc_clusters(bs, s->l1_size * sizeof(uint64_t)); sn->l1_size = s->l1_size; l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t)); if (!l1_table) goto fail; for(i = 0; i < s->l1_size; i++) { l1_table[i] = cpu_to_be64(s->l1_table[i]); } if (bdrv_pwrite(s->hd, sn->l1_table_offset, l1_table, s->l1_size * sizeof(uint64_t)) != (s->l1_size * sizeof(uint64_t))) goto fail; qemu_free(l1_table); l1_table = NULL; snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot)); if (!snapshots1) goto fail; memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot)); s->snapshots = snapshots1; s->snapshots[s->nb_snapshots++] = *sn; if (qcow_write_snapshots(bs) < 0) goto fail; #ifdef DEBUG_ALLOC check_refcounts(bs); #endif return 0; fail: qemu_free(sn->name); qemu_free(l1_table); return -1; } /* copy the snapshot 'snapshot_name' into the current disk image */ static int qcow_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) { BDRVQcowState *s = bs->opaque; QCowSnapshot *sn; int i, snapshot_index, l1_size2; snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); if (snapshot_index < 0) return -ENOENT; sn = &s->snapshots[snapshot_index]; if (update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0) goto fail; if (grow_l1_table(bs, sn->l1_size) < 0) goto fail; s->l1_size = sn->l1_size; l1_size2 = s->l1_size * sizeof(uint64_t); /* copy the snapshot l1 table to the current l1 table */ if (bdrv_pread(s->hd, sn->l1_table_offset, s->l1_table, l1_size2) != l1_size2) goto fail; if (bdrv_pwrite(s->hd, s->l1_table_offset, s->l1_table, l1_size2) != l1_size2) goto fail; for(i = 0;i < s->l1_size; i++) { be64_to_cpus(&s->l1_table[i]); } if (update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0) goto fail; #ifdef DEBUG_ALLOC check_refcounts(bs); #endif return 0; fail: return -EIO; } static int qcow_snapshot_delete(BlockDriverState *bs, const char *snapshot_id) { BDRVQcowState *s = bs->opaque; QCowSnapshot *sn; int snapshot_index, ret; snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); if (snapshot_index < 0) return -ENOENT; sn = &s->snapshots[snapshot_index]; ret = update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1); if (ret < 0) return ret; /* must update the copied flag on the current cluster offsets */ ret = update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0); if (ret < 0) return ret; free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t)); qemu_free(sn->id_str); qemu_free(sn->name); memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn)); s->nb_snapshots--; ret = qcow_write_snapshots(bs); if (ret < 0) { /* XXX: restore snapshot if error ? */ return ret; } #ifdef DEBUG_ALLOC check_refcounts(bs); #endif return 0; } static int qcow_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab) { BDRVQcowState *s = bs->opaque; QEMUSnapshotInfo *sn_tab, *sn_info; QCowSnapshot *sn; int i; sn_tab = qemu_mallocz(s->nb_snapshots * sizeof(QEMUSnapshotInfo)); if (!sn_tab) goto fail; for(i = 0; i < s->nb_snapshots; i++) { sn_info = sn_tab + i; sn = s->snapshots + i; pstrcpy(sn_info->id_str, sizeof(sn_info->id_str), sn->id_str); pstrcpy(sn_info->name, sizeof(sn_info->name), sn->name); sn_info->vm_state_size = sn->vm_state_size; sn_info->date_sec = sn->date_sec; sn_info->date_nsec = sn->date_nsec; sn_info->vm_clock_nsec = sn->vm_clock_nsec; } *psn_tab = sn_tab; return s->nb_snapshots; fail: qemu_free(sn_tab); *psn_tab = NULL; return -ENOMEM; } /*********************************************************/ /* refcount handling */ static int refcount_init(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; int ret, refcount_table_size2, i; s->refcount_block_cache = qemu_malloc(s->cluster_size); if (!s->refcount_block_cache) goto fail; refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t); s->refcount_table = qemu_malloc(refcount_table_size2); if (!s->refcount_table) goto fail; if (s->refcount_table_size > 0) { ret = bdrv_pread(s->hd, s->refcount_table_offset, s->refcount_table, refcount_table_size2); if (ret != refcount_table_size2) goto fail; for(i = 0; i < s->refcount_table_size; i++) be64_to_cpus(&s->refcount_table[i]); } return 0; fail: return -ENOMEM; } static void refcount_close(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; qemu_free(s->refcount_block_cache); qemu_free(s->refcount_table); } static int load_refcount_block(BlockDriverState *bs, int64_t refcount_block_offset) { BDRVQcowState *s = bs->opaque; int ret; ret = bdrv_pread(s->hd, refcount_block_offset, s->refcount_block_cache, s->cluster_size); if (ret != s->cluster_size) return -EIO; s->refcount_block_cache_offset = refcount_block_offset; return 0; } static int get_refcount(BlockDriverState *bs, int64_t cluster_index) { BDRVQcowState *s = bs->opaque; int refcount_table_index, block_index; int64_t refcount_block_offset; refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); if (refcount_table_index >= s->refcount_table_size) return 0; refcount_block_offset = s->refcount_table[refcount_table_index]; if (!refcount_block_offset) return 0; if (refcount_block_offset != s->refcount_block_cache_offset) { /* better than nothing: return allocated if read error */ if (load_refcount_block(bs, refcount_block_offset) < 0) return 1; } block_index = cluster_index & ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); return be16_to_cpu(s->refcount_block_cache[block_index]); } /* return < 0 if error */ static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size) { BDRVQcowState *s = bs->opaque; int i, nb_clusters; nb_clusters = (size + s->cluster_size - 1) >> s->cluster_bits; for(;;) { if (get_refcount(bs, s->free_cluster_index) == 0) { s->free_cluster_index++; for(i = 1; i < nb_clusters; i++) { if (get_refcount(bs, s->free_cluster_index) != 0) goto not_found; s->free_cluster_index++; } #ifdef DEBUG_ALLOC2 printf("alloc_clusters: size=%lld -> %lld\n", size, (s->free_cluster_index - nb_clusters) << s->cluster_bits); #endif return (s->free_cluster_index - nb_clusters) << s->cluster_bits; } else { not_found: s->free_cluster_index++; } } } static int64_t alloc_clusters(BlockDriverState *bs, int64_t size) { int64_t offset; offset = alloc_clusters_noref(bs, size); update_refcount(bs, offset, size, 1); return offset; } /* only used to allocate compressed sectors. We try to allocate contiguous sectors. size must be <= cluster_size */ static int64_t alloc_bytes(BlockDriverState *bs, int size) { BDRVQcowState *s = bs->opaque; int64_t offset, cluster_offset; int free_in_cluster; assert(size > 0 && size <= s->cluster_size); if (s->free_byte_offset == 0) { s->free_byte_offset = alloc_clusters(bs, s->cluster_size); } redo: free_in_cluster = s->cluster_size - (s->free_byte_offset & (s->cluster_size - 1)); if (size <= free_in_cluster) { /* enough space in current cluster */ offset = s->free_byte_offset; s->free_byte_offset += size; free_in_cluster -= size; if (free_in_cluster == 0) s->free_byte_offset = 0; if ((offset & (s->cluster_size - 1)) != 0) update_cluster_refcount(bs, offset >> s->cluster_bits, 1); } else { offset = alloc_clusters(bs, s->cluster_size); cluster_offset = s->free_byte_offset & ~(s->cluster_size - 1); if ((cluster_offset + s->cluster_size) == offset) { /* we are lucky: contiguous data */ offset = s->free_byte_offset; update_cluster_refcount(bs, offset >> s->cluster_bits, 1); s->free_byte_offset += size; } else { s->free_byte_offset = offset; goto redo; } } return offset; } static void free_clusters(BlockDriverState *bs, int64_t offset, int64_t size) { update_refcount(bs, offset, size, -1); } static int grow_refcount_table(BlockDriverState *bs, int min_size) { BDRVQcowState *s = bs->opaque; int new_table_size, new_table_size2, refcount_table_clusters, i, ret; uint64_t *new_table; int64_t table_offset; uint64_t data64; uint32_t data32; int old_table_size; int64_t old_table_offset; if (min_size <= s->refcount_table_size) return 0; /* compute new table size */ refcount_table_clusters = s->refcount_table_size >> (s->cluster_bits - 3); for(;;) { if (refcount_table_clusters == 0) { refcount_table_clusters = 1; } else { refcount_table_clusters = (refcount_table_clusters * 3 + 1) / 2; } new_table_size = refcount_table_clusters << (s->cluster_bits - 3); if (min_size <= new_table_size) break; } #ifdef DEBUG_ALLOC2 printf("grow_refcount_table from %d to %d\n", s->refcount_table_size, new_table_size); #endif new_table_size2 = new_table_size * sizeof(uint64_t); new_table = qemu_mallocz(new_table_size2); if (!new_table) return -ENOMEM; memcpy(new_table, s->refcount_table, s->refcount_table_size * sizeof(uint64_t)); for(i = 0; i < s->refcount_table_size; i++) cpu_to_be64s(&new_table[i]); /* Note: we cannot update the refcount now to avoid recursion */ table_offset = alloc_clusters_noref(bs, new_table_size2); ret = bdrv_pwrite(s->hd, table_offset, new_table, new_table_size2); if (ret != new_table_size2) goto fail; for(i = 0; i < s->refcount_table_size; i++) be64_to_cpus(&new_table[i]); data64 = cpu_to_be64(table_offset); if (bdrv_pwrite(s->hd, offsetof(QCowHeader, refcount_table_offset), &data64, sizeof(data64)) != sizeof(data64)) goto fail; data32 = cpu_to_be32(refcount_table_clusters); if (bdrv_pwrite(s->hd, offsetof(QCowHeader, refcount_table_clusters), &data32, sizeof(data32)) != sizeof(data32)) goto fail; qemu_free(s->refcount_table); old_table_offset = s->refcount_table_offset; old_table_size = s->refcount_table_size; s->refcount_table = new_table; s->refcount_table_size = new_table_size; s->refcount_table_offset = table_offset; update_refcount(bs, table_offset, new_table_size2, 1); free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t)); return 0; fail: free_clusters(bs, table_offset, new_table_size2); qemu_free(new_table); return -EIO; } /* addend must be 1 or -1 */ /* XXX: cache several refcount block clusters ? */ static int update_cluster_refcount(BlockDriverState *bs, int64_t cluster_index, int addend) { BDRVQcowState *s = bs->opaque; int64_t offset, refcount_block_offset; int ret, refcount_table_index, block_index, refcount; uint64_t data64; refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); if (refcount_table_index >= s->refcount_table_size) { if (addend < 0) return -EINVAL; ret = grow_refcount_table(bs, refcount_table_index + 1); if (ret < 0) return ret; } refcount_block_offset = s->refcount_table[refcount_table_index]; if (!refcount_block_offset) { if (addend < 0) return -EINVAL; /* create a new refcount block */ /* Note: we cannot update the refcount now to avoid recursion */ offset = alloc_clusters_noref(bs, s->cluster_size); memset(s->refcount_block_cache, 0, s->cluster_size); ret = bdrv_pwrite(s->hd, offset, s->refcount_block_cache, s->cluster_size); if (ret != s->cluster_size) return -EINVAL; s->refcount_table[refcount_table_index] = offset; data64 = cpu_to_be64(offset); ret = bdrv_pwrite(s->hd, s->refcount_table_offset + refcount_table_index * sizeof(uint64_t), &data64, sizeof(data64)); if (ret != sizeof(data64)) return -EINVAL; refcount_block_offset = offset; s->refcount_block_cache_offset = offset; update_refcount(bs, offset, s->cluster_size, 1); } else { if (refcount_block_offset != s->refcount_block_cache_offset) { if (load_refcount_block(bs, refcount_block_offset) < 0) return -EIO; } } /* we can update the count and save it */ block_index = cluster_index & ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); refcount = be16_to_cpu(s->refcount_block_cache[block_index]); refcount += addend; if (refcount < 0 || refcount > 0xffff) return -EINVAL; if (refcount == 0 && cluster_index < s->free_cluster_index) { s->free_cluster_index = cluster_index; } s->refcount_block_cache[block_index] = cpu_to_be16(refcount); if (bdrv_pwrite(s->hd, refcount_block_offset + (block_index << REFCOUNT_SHIFT), &s->refcount_block_cache[block_index], 2) != 2) return -EIO; return refcount; } static void update_refcount(BlockDriverState *bs, int64_t offset, int64_t length, int addend) { BDRVQcowState *s = bs->opaque; int64_t start, last, cluster_offset; #ifdef DEBUG_ALLOC2 printf("update_refcount: offset=%lld size=%lld addend=%d\n", offset, length, addend); #endif if (length <= 0) return; start = offset & ~(s->cluster_size - 1); last = (offset + length - 1) & ~(s->cluster_size - 1); for(cluster_offset = start; cluster_offset <= last; cluster_offset += s->cluster_size) { update_cluster_refcount(bs, cluster_offset >> s->cluster_bits, addend); } } #ifdef DEBUG_ALLOC static void inc_refcounts(BlockDriverState *bs, uint16_t *refcount_table, int refcount_table_size, int64_t offset, int64_t size) { BDRVQcowState *s = bs->opaque; int64_t start, last, cluster_offset; int k; if (size <= 0) return; start = offset & ~(s->cluster_size - 1); last = (offset + size - 1) & ~(s->cluster_size - 1); for(cluster_offset = start; cluster_offset <= last; cluster_offset += s->cluster_size) { k = cluster_offset >> s->cluster_bits; if (k < 0 || k >= refcount_table_size) { printf("ERROR: invalid cluster offset=0x%llx\n", cluster_offset); } else { if (++refcount_table[k] == 0) { printf("ERROR: overflow cluster offset=0x%llx\n", cluster_offset); } } } } static int check_refcounts_l1(BlockDriverState *bs, uint16_t *refcount_table, int refcount_table_size, int64_t l1_table_offset, int l1_size, int check_copied) { BDRVQcowState *s = bs->opaque; uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2; int l2_size, i, j, nb_csectors, refcount; l2_table = NULL; l1_size2 = l1_size * sizeof(uint64_t); inc_refcounts(bs, refcount_table, refcount_table_size, l1_table_offset, l1_size2); l1_table = qemu_malloc(l1_size2); if (!l1_table) goto fail; if (bdrv_pread(s->hd, l1_table_offset, l1_table, l1_size2) != l1_size2) goto fail; for(i = 0;i < l1_size; i++) be64_to_cpus(&l1_table[i]); l2_size = s->l2_size * sizeof(uint64_t); l2_table = qemu_malloc(l2_size); if (!l2_table) goto fail; for(i = 0; i < l1_size; i++) { l2_offset = l1_table[i]; if (l2_offset) { if (check_copied) { refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED) >> s->cluster_bits); if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) { printf("ERROR OFLAG_COPIED: l2_offset=%llx refcount=%d\n", l2_offset, refcount); } } l2_offset &= ~QCOW_OFLAG_COPIED; if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size) goto fail; for(j = 0; j < s->l2_size; j++) { offset = be64_to_cpu(l2_table[j]); if (offset != 0) { if (offset & QCOW_OFLAG_COMPRESSED) { if (offset & QCOW_OFLAG_COPIED) { printf("ERROR: cluster %lld: copied flag must never be set for compressed clusters\n", offset >> s->cluster_bits); offset &= ~QCOW_OFLAG_COPIED; } nb_csectors = ((offset >> s->csize_shift) & s->csize_mask) + 1; offset &= s->cluster_offset_mask; inc_refcounts(bs, refcount_table, refcount_table_size, offset & ~511, nb_csectors * 512); } else { if (check_copied) { refcount = get_refcount(bs, (offset & ~QCOW_OFLAG_COPIED) >> s->cluster_bits); if ((refcount == 1) != ((offset & QCOW_OFLAG_COPIED) != 0)) { printf("ERROR OFLAG_COPIED: offset=%llx refcount=%d\n", offset, refcount); } } offset &= ~QCOW_OFLAG_COPIED; inc_refcounts(bs, refcount_table, refcount_table_size, offset, s->cluster_size); } } } inc_refcounts(bs, refcount_table, refcount_table_size, l2_offset, s->cluster_size); } } qemu_free(l1_table); qemu_free(l2_table); return 0; fail: printf("ERROR: I/O error in check_refcounts_l1\n"); qemu_free(l1_table); qemu_free(l2_table); return -EIO; } static void check_refcounts(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; int64_t size; int nb_clusters, refcount1, refcount2, i; QCowSnapshot *sn; uint16_t *refcount_table; size = bdrv_getlength(s->hd); nb_clusters = (size + s->cluster_size - 1) >> s->cluster_bits; refcount_table = qemu_mallocz(nb_clusters * sizeof(uint16_t)); /* header */ inc_refcounts(bs, refcount_table, nb_clusters, 0, s->cluster_size); check_refcounts_l1(bs, refcount_table, nb_clusters, s->l1_table_offset, s->l1_size, 1); /* snapshots */ for(i = 0; i < s->nb_snapshots; i++) { sn = s->snapshots + i; check_refcounts_l1(bs, refcount_table, nb_clusters, sn->l1_table_offset, sn->l1_size, 0); } inc_refcounts(bs, refcount_table, nb_clusters, s->snapshots_offset, s->snapshots_size); /* refcount data */ inc_refcounts(bs, refcount_table, nb_clusters, s->refcount_table_offset, s->refcount_table_size * sizeof(uint64_t)); for(i = 0; i < s->refcount_table_size; i++) { int64_t offset; offset = s->refcount_table[i]; if (offset != 0) { inc_refcounts(bs, refcount_table, nb_clusters, offset, s->cluster_size); } } /* compare ref counts */ for(i = 0; i < nb_clusters; i++) { refcount1 = get_refcount(bs, i); refcount2 = refcount_table[i]; if (refcount1 != refcount2) printf("ERROR cluster %d refcount=%d reference=%d\n", i, refcount1, refcount2); } qemu_free(refcount_table); } #if 0 static void dump_refcounts(BlockDriverState *bs) { BDRVQcowState *s = bs->opaque; int64_t nb_clusters, k, k1, size; int refcount; size = bdrv_getlength(s->hd); nb_clusters = (size + s->cluster_size - 1) >> s->cluster_bits; 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("%lld: refcount=%d nb=%lld\n", k, refcount, k - k1); } } #endif #endif BlockDriver bdrv_qcow2 = { "qcow2", sizeof(BDRVQcowState), qcow_probe, qcow_open, NULL, NULL, qcow_close, qcow_create, qcow_flush, qcow_is_allocated, qcow_set_key, qcow_make_empty, .bdrv_aio_read = qcow_aio_read, .bdrv_aio_write = qcow_aio_write, .bdrv_aio_cancel = qcow_aio_cancel, .aiocb_size = sizeof(QCowAIOCB), .bdrv_write_compressed = qcow_write_compressed, .bdrv_snapshot_create = qcow_snapshot_create, .bdrv_snapshot_goto = qcow_snapshot_goto, .bdrv_snapshot_delete = qcow_snapshot_delete, .bdrv_snapshot_list = qcow_snapshot_list, .bdrv_get_info = qcow_get_info, };