diff options
Diffstat (limited to 'block/qcow2-cluster.c')
| -rw-r--r-- | block/qcow2-cluster.c | 754 |
1 files changed, 754 insertions, 0 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c new file mode 100644 index 0000000000..494cc91220 --- /dev/null +++ b/block/qcow2-cluster.c @@ -0,0 +1,754 @@ +/* + * 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 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; + uint8_t data[12]; + + 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); + 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 */ + cpu_to_be32w((uint32_t*)data, new_l1_size); + cpu_to_be64w((uint64_t*)(data + 4), new_l1_table_offset); + if (bdrv_pwrite(s->hd, offsetof(QCowHeader, l1_size), data, + sizeof(data)) != sizeof(data)) + 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; +} + +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; +} + +/* + * 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; +} + +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 + 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 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; + cluster_offset = get_cluster_offset(bs, sector_num << 9, &n); + index_in_cluster = sector_num & (s->cluster_sectors - 1); + 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 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; +} + + +/* + * get_cluster_offset + * + * For a given offset of the disk image, return cluster offset in + * qcow2 file. + * + * 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 1, if the offset is found + * Return 0, otherwise. + * + */ + +uint64_t get_cluster_offset(BlockDriverState *bs, uint64_t offset, int *num) +{ + BDRVQcowState *s = bs->opaque; + int l1_index, l2_index; + uint64_t l2_offset, *l2_table, cluster_offset; + int l1_bits, c; + int index_in_cluster, nb_available, nb_needed, nb_clusters; + + 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 = (1 << l1_bits) - (offset & ((1 << 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; + 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]); + 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; + + return cluster_offset & ~QCOW_OFLAG_COPIED; +} + +/* + * 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. + * + */ + +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; + int l1_index, l2_index, ret; + uint64_t l2_offset, *l2_table; + + /* 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); + + *new_l2_table = l2_table; + *new_l2_offset = l2_offset; + *new_l2_index = l2_index; + + return 1; +} + +/* + * 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 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, 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) + free_any_clusters(bs, cluster_offset, 1); + + 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; +} + +int alloc_cluster_link_l2(BlockDriverState *bs, uint64_t cluster_offset, + QCowL2Meta *m) +{ + BDRVQcowState *s = bs->opaque; + int i, j = 0, l2_index, ret; + uint64_t *old_cluster, start_sect, l2_offset, *l2_table; + + 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; + } + + ret = -EIO; + /* update L2 table */ + if (!get_cluster_table(bs, m->offset, &l2_table, &l2_offset, &l2_index)) + 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); + } + + if (bdrv_pwrite(s->hd, l2_offset + l2_index * sizeof(uint64_t), + l2_table + l2_index, m->nb_clusters * sizeof(uint64_t)) != + m->nb_clusters * sizeof(uint64_t)) + goto err; + + for (i = 0; i < j; i++) + 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. + * + * Return the cluster offset if successful, + * Return 0, otherwise. + * + */ + +uint64_t 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, cluster_offset; + int nb_clusters, i = 0; + + ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index); + if (ret == 0) + return 0; + + 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; + + 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(be64_to_cpu(l2_table[l2_index + i])) + break; + + i += count_contiguous_free_clusters(nb_clusters - i, + &l2_table[l2_index + i]); + + cluster_offset = be64_to_cpu(l2_table[l2_index + i]); + + if ((cluster_offset & QCOW_OFLAG_COPIED) || + (cluster_offset & QCOW_OFLAG_COMPRESSED)) + break; + } + nb_clusters = i; + + /* allocate a new cluster */ + + cluster_offset = alloc_clusters(bs, nb_clusters * s->cluster_size); + + /* 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); + + *num = m->nb_available - n_start; + + return cluster_offset; +} + +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 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; +} |