/* * 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 <zlib.h> #include "qemu-common.h" #include "block_int.h" #include "block/qcow2.h" int qcow2_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; int64_t new_l1_table_offset; uint8_t data[12]; new_l1_size = s->l1_size; if (min_size <= new_l1_size) return 0; if (new_l1_size == 0) { new_l1_size = 1; } 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(align_offset(new_l1_size2, 512)); memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t)); /* write new table (align to cluster) */ BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ALLOC_TABLE); new_l1_table_offset = qcow2_alloc_clusters(bs, new_l1_size2); if (new_l1_table_offset < 0) { qemu_free(new_l1_table); return new_l1_table_offset; } BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_WRITE_TABLE); for(i = 0; i < s->l1_size; i++) new_l1_table[i] = cpu_to_be64(new_l1_table[i]); ret = bdrv_pwrite_sync(bs->file, new_l1_table_offset, new_l1_table, new_l1_size2); if (ret < 0) goto fail; for(i = 0; i < s->l1_size; i++) new_l1_table[i] = be64_to_cpu(new_l1_table[i]); /* set new table */ BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ACTIVATE_TABLE); cpu_to_be32w((uint32_t*)data, new_l1_size); cpu_to_be64w((uint64_t*)(data + 4), new_l1_table_offset); ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_size), data,sizeof(data)); if (ret < 0) { goto fail; } qemu_free(s->l1_table); qcow2_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(new_l1_table); qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2); return ret; } void qcow2_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; } /* * 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 int l2_load(BlockDriverState *bs, uint64_t l2_offset, uint64_t **l2_table) { BDRVQcowState *s = bs->opaque; int min_index; int ret; /* 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 0; } /* 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); BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD); ret = bdrv_pread(bs->file, l2_offset, *l2_table, s->l2_size * sizeof(uint64_t)); if (ret < 0) { return ret; } s->l2_cache_offsets[min_index] = l2_offset; s->l2_cache_counts[min_index] = 1; return 0; } /* * Writes one sector of the L1 table to the disk (can't update single entries * and we really don't want bdrv_pread to perform a read-modify-write) */ #define L1_ENTRIES_PER_SECTOR (512 / 8) static int write_l1_entry(BlockDriverState *bs, int l1_index) { BDRVQcowState *s = bs->opaque; uint64_t buf[L1_ENTRIES_PER_SECTOR]; int l1_start_index; int i, ret; l1_start_index = l1_index & ~(L1_ENTRIES_PER_SECTOR - 1); for (i = 0; i < L1_ENTRIES_PER_SECTOR; i++) { buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]); } BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE); ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset + 8 * l1_start_index, buf, sizeof(buf)); if (ret < 0) { return ret; } return 0; } /* * 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 int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table) { BDRVQcowState *s = bs->opaque; int min_index; uint64_t old_l2_offset; uint64_t *l2_table; int64_t l2_offset; int ret; old_l2_offset = s->l1_table[l1_index]; /* allocate a new l2 entry */ l2_offset = qcow2_alloc_clusters(bs, s->l2_size * sizeof(uint64_t)); if (l2_offset < 0) { return l2_offset; } /* 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 */ BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ); ret = bdrv_pread(bs->file, old_l2_offset, l2_table, s->l2_size * sizeof(uint64_t)); if (ret < 0) { goto fail; } } /* write the l2 table to the file */ BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE); ret = bdrv_pwrite_sync(bs->file, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)); if (ret < 0) { goto fail; } /* update the L1 entry */ s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED; ret = write_l1_entry(bs, l1_index); if (ret < 0) { goto fail; } /* update the l2 cache entry */ s->l2_cache_offsets[min_index] = l2_offset; s->l2_cache_counts[min_index] = 1; *table = l2_table; return 0; fail: s->l1_table[l1_index] = old_l2_offset; qcow2_l2_cache_reset(bs); return ret; } static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size, uint64_t *l2_table, uint64_t start, uint64_t mask) { int i; uint64_t offset = be64_to_cpu(l2_table[0]) & ~mask; if (!offset) return 0; for (i = start; i < start + nb_clusters; i++) if (offset + (uint64_t) i * cluster_size != (be64_to_cpu(l2_table[i]) & ~mask)) break; return (i - start); } static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t *l2_table) { int i = 0; while(nb_clusters-- && l2_table[i] == 0) i++; return i; } /* The crypt function is compatible with the linux cryptoloop algorithm for < 4 GB images. NOTE: out_buf == in_buf is supported */ void qcow2_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 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) { n = nb_sectors; ret = qcow2_get_cluster_offset(bs, sector_num << 9, &n, &cluster_offset); if (ret < 0) { return ret; } index_in_cluster = sector_num & (s->cluster_sectors - 1); if (!cluster_offset) { if (bs->backing_hd) { /* read from the base image */ n1 = qcow2_backing_read1(bs->backing_hd, sector_num, buf, n); if (n1 > 0) { BLKDBG_EVENT(bs->file, BLKDBG_READ_BACKING); 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 (qcow2_decompress_cluster(bs, cluster_offset) < 0) return -1; memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n); } else { BLKDBG_EVENT(bs->file, BLKDBG_READ); ret = bdrv_pread(bs->file, cluster_offset + index_in_cluster * 512, buf, n * 512); if (ret != n * 512) return -1; if (s->crypt_method) { qcow2_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 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; BLKDBG_EVENT(bs->file, BLKDBG_COW_READ); ret = qcow_read(bs, start_sect + n_start, s->cluster_data, n); if (ret < 0) return ret; if (s->crypt_method) { qcow2_encrypt_sectors(s, start_sect + n_start, s->cluster_data, s->cluster_data, n, 1, &s->aes_encrypt_key); } BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE); ret = bdrv_write_sync(bs->file, (cluster_offset >> 9) + n_start, s->cluster_data, n); if (ret < 0) return ret; return 0; } /* * get_cluster_offset * * For a given offset of the disk image, find the cluster offset in * qcow2 file. The offset is stored in *cluster_offset. * * on entry, *num is the number of contiguous clusters we'd like to * access following offset. * * on exit, *num is the number of contiguous clusters we can read. * * Return 0, if the offset is found * Return -errno, otherwise. * */ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, int *num, uint64_t *cluster_offset) { BDRVQcowState *s = bs->opaque; unsigned int l1_index, l2_index; uint64_t l2_offset, *l2_table; int l1_bits, c; unsigned int index_in_cluster, nb_clusters; uint64_t nb_available, nb_needed; int ret; index_in_cluster = (offset >> 9) & (s->cluster_sectors - 1); nb_needed = *num + index_in_cluster; l1_bits = s->l2_bits + s->cluster_bits; /* compute how many bytes there are between the offset and * the end of the l1 entry */ nb_available = (1ULL << l1_bits) - (offset & ((1ULL << l1_bits) - 1)); /* compute the number of available sectors */ nb_available = (nb_available >> 9) + index_in_cluster; if (nb_needed > nb_available) { nb_needed = nb_available; } *cluster_offset = 0; /* seek the the l2 offset in the l1 table */ l1_index = offset >> l1_bits; if (l1_index >= s->l1_size) goto out; l2_offset = s->l1_table[l1_index]; /* seek the l2 table of the given l2 offset */ if (!l2_offset) goto out; /* load the l2 table in memory */ l2_offset &= ~QCOW_OFLAG_COPIED; ret = l2_load(bs, l2_offset, &l2_table); if (ret < 0) { return ret; } /* 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]); nb_clusters = size_to_clusters(s, nb_needed << 9); if (!*cluster_offset) { /* how many empty clusters ? */ c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]); } else { /* how many allocated clusters ? */ c = count_contiguous_clusters(nb_clusters, s->cluster_size, &l2_table[l2_index], 0, QCOW_OFLAG_COPIED); } nb_available = (c * s->cluster_sectors); out: if (nb_available > nb_needed) nb_available = nb_needed; *num = nb_available - index_in_cluster; *cluster_offset &=~QCOW_OFLAG_COPIED; return 0; } /* * get_cluster_table * * for a given disk offset, load (and allocate if needed) * the l2 table. * * the l2 table offset in the qcow2 file and the cluster index * in the l2 table are given to the caller. * * Returns 0 on success, -errno in failure case */ static int get_cluster_table(BlockDriverState *bs, uint64_t offset, uint64_t **new_l2_table, uint64_t *new_l2_offset, int *new_l2_index) { BDRVQcowState *s = bs->opaque; unsigned int l1_index, l2_index; uint64_t l2_offset; uint64_t *l2_table = NULL; int ret; /* 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 = qcow2_grow_l1_table(bs, l1_index + 1); if (ret < 0) { return ret; } } 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; ret = l2_load(bs, l2_offset, &l2_table); if (ret < 0) { return ret; } } else { if (l2_offset) qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t)); ret = l2_allocate(bs, l1_index, &l2_table); if (ret < 0) { return ret; } 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); *new_l2_table = l2_table; *new_l2_offset = l2_offset; *new_l2_index = l2_index; return 0; } /* * alloc_compressed_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 compressed cluster. * * Return the cluster offset if successful, * Return 0, otherwise. * */ uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs, uint64_t offset, int compressed_size) { BDRVQcowState *s = bs->opaque; int l2_index, ret; uint64_t l2_offset, *l2_table; int64_t cluster_offset; int nb_csectors; ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index); if (ret < 0) { return 0; } cluster_offset = be64_to_cpu(l2_table[l2_index]); if (cluster_offset & QCOW_OFLAG_COPIED) return cluster_offset & ~QCOW_OFLAG_COPIED; if (cluster_offset) qcow2_free_any_clusters(bs, cluster_offset, 1); cluster_offset = qcow2_alloc_bytes(bs, compressed_size); if (cluster_offset < 0) { return 0; } 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 */ BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED); l2_table[l2_index] = cpu_to_be64(cluster_offset); if (bdrv_pwrite_sync(bs->file, l2_offset + l2_index * sizeof(uint64_t), l2_table + l2_index, sizeof(uint64_t)) < 0) return 0; return cluster_offset; } /* * Write L2 table updates to disk, writing whole sectors to avoid a * read-modify-write in bdrv_pwrite */ #define L2_ENTRIES_PER_SECTOR (512 / 8) static int write_l2_entries(BlockDriverState *bs, uint64_t *l2_table, uint64_t l2_offset, int l2_index, int num) { int l2_start_index = l2_index & ~(L1_ENTRIES_PER_SECTOR - 1); int start_offset = (8 * l2_index) & ~511; int end_offset = (8 * (l2_index + num) + 511) & ~511; size_t len = end_offset - start_offset; int ret; BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE); ret = bdrv_pwrite_sync(bs->file, l2_offset + start_offset, &l2_table[l2_start_index], len); if (ret < 0) { return ret; } return 0; } int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) { BDRVQcowState *s = bs->opaque; int i, j = 0, l2_index, ret; uint64_t *old_cluster, start_sect, l2_offset, *l2_table; uint64_t cluster_offset = m->cluster_offset; if (m->nb_clusters == 0) return 0; old_cluster = qemu_malloc(m->nb_clusters * sizeof(uint64_t)); /* copy content of unmodified sectors */ start_sect = (m->offset & ~(s->cluster_size - 1)) >> 9; if (m->n_start) { ret = copy_sectors(bs, start_sect, cluster_offset, 0, m->n_start); if (ret < 0) goto err; } if (m->nb_available & (s->cluster_sectors - 1)) { uint64_t end = m->nb_available & ~(uint64_t)(s->cluster_sectors - 1); ret = copy_sectors(bs, start_sect + end, cluster_offset + (end << 9), m->nb_available - end, s->cluster_sectors); if (ret < 0) goto err; } /* update L2 table */ ret = get_cluster_table(bs, m->offset, &l2_table, &l2_offset, &l2_index); if (ret < 0) { goto err; } for (i = 0; i < m->nb_clusters; i++) { /* if two concurrent writes happen to the same unallocated cluster * each write allocates separate cluster and writes data concurrently. * The first one to complete updates l2 table with pointer to its * cluster the second one has to do RMW (which is done above by * copy_sectors()), update l2 table with its cluster pointer and free * old cluster. This is what this loop does */ if(l2_table[l2_index + i] != 0) old_cluster[j++] = l2_table[l2_index + i]; l2_table[l2_index + i] = cpu_to_be64((cluster_offset + (i << s->cluster_bits)) | QCOW_OFLAG_COPIED); } ret = write_l2_entries(bs, l2_table, l2_offset, l2_index, m->nb_clusters); if (ret < 0) { qcow2_l2_cache_reset(bs); goto err; } for (i = 0; i < j; i++) qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]) & ~QCOW_OFLAG_COPIED, 1); ret = 0; err: qemu_free(old_cluster); return ret; } /* * 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. * * If the cluster was already allocated, m->nb_clusters is set to 0, * m->depends_on is set to NULL and the other fields in m are meaningless. * * If the cluster is newly allocated, m->nb_clusters is set to the number of * contiguous clusters that have been allocated. This may be 0 if the request * conflict with another write request in flight; in this case, m->depends_on * is set and the remaining fields of m are meaningless. * * If m->nb_clusters is non-zero, the other fields of m are valid and contain * information about the first allocated cluster. * * Return 0 on success and -errno in error cases */ int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset, int n_start, int n_end, int *num, QCowL2Meta *m) { BDRVQcowState *s = bs->opaque; int l2_index, ret; uint64_t l2_offset, *l2_table; int64_t cluster_offset; unsigned int nb_clusters, i = 0; QCowL2Meta *old_alloc; ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index); if (ret < 0) { return ret; } nb_clusters = size_to_clusters(s, n_end << 9); nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); cluster_offset = be64_to_cpu(l2_table[l2_index]); /* We keep all QCOW_OFLAG_COPIED clusters */ if (cluster_offset & QCOW_OFLAG_COPIED) { nb_clusters = count_contiguous_clusters(nb_clusters, s->cluster_size, &l2_table[l2_index], 0, 0); cluster_offset &= ~QCOW_OFLAG_COPIED; m->nb_clusters = 0; m->depends_on = NULL; goto out; } /* for the moment, multiple compressed clusters are not managed */ if (cluster_offset & QCOW_OFLAG_COMPRESSED) nb_clusters = 1; /* how many available clusters ? */ while (i < nb_clusters) { i += count_contiguous_clusters(nb_clusters - i, s->cluster_size, &l2_table[l2_index], i, 0); if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) { break; } i += count_contiguous_free_clusters(nb_clusters - i, &l2_table[l2_index + i]); if (i >= nb_clusters) { break; } cluster_offset = be64_to_cpu(l2_table[l2_index + i]); if ((cluster_offset & QCOW_OFLAG_COPIED) || (cluster_offset & QCOW_OFLAG_COMPRESSED)) break; } assert(i <= nb_clusters); nb_clusters = i; /* * Check if there already is an AIO write request in flight which allocates * the same cluster. In this case we need to wait until the previous * request has completed and updated the L2 table accordingly. */ QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) { uint64_t end_offset = offset + nb_clusters * s->cluster_size; uint64_t old_offset = old_alloc->offset; uint64_t old_end_offset = old_alloc->offset + old_alloc->nb_clusters * s->cluster_size; if (end_offset < old_offset || offset > old_end_offset) { /* No intersection */ } else { if (offset < old_offset) { /* Stop at the start of a running allocation */ nb_clusters = (old_offset - offset) >> s->cluster_bits; } else { nb_clusters = 0; } if (nb_clusters == 0) { /* Set dependency and wait for a callback */ m->depends_on = old_alloc; m->nb_clusters = 0; *num = 0; return 0; } } } if (!nb_clusters) { abort(); } QLIST_INSERT_HEAD(&s->cluster_allocs, m, next_in_flight); /* allocate a new cluster */ cluster_offset = qcow2_alloc_clusters(bs, nb_clusters * s->cluster_size); if (cluster_offset < 0) { QLIST_REMOVE(m, next_in_flight); return cluster_offset; } /* save info needed for meta data update */ m->offset = offset; m->n_start = n_start; m->nb_clusters = nb_clusters; out: m->nb_available = MIN(nb_clusters << (s->cluster_bits - 9), n_end); m->cluster_offset = cluster_offset; *num = m->nb_available - n_start; return 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; } int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset) { BDRVQcowState *s = bs->opaque; 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; BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED); ret = bdrv_read(bs->file, 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; }