diff options
Diffstat (limited to 'qemu/block/qcow2-cluster.c')
| -rw-r--r-- | qemu/block/qcow2-cluster.c | 1879 |
1 files changed, 1879 insertions, 0 deletions
diff --git a/qemu/block/qcow2-cluster.c b/qemu/block/qcow2-cluster.c new file mode 100644 index 000000000..b43f186eb --- /dev/null +++ b/qemu/block/qcow2-cluster.c @@ -0,0 +1,1879 @@ +/* + * 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/block_int.h" +#include "block/qcow2.h" +#include "trace.h" + +int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size, + bool exact_size) +{ + BDRVQcowState *s = bs->opaque; + int new_l1_size2, ret, i; + uint64_t *new_l1_table; + int64_t old_l1_table_offset, old_l1_size; + int64_t new_l1_table_offset, new_l1_size; + uint8_t data[12]; + + if (min_size <= s->l1_size) + return 0; + + /* Do a sanity check on min_size before trying to calculate new_l1_size + * (this prevents overflows during the while loop for the calculation of + * new_l1_size) */ + if (min_size > INT_MAX / sizeof(uint64_t)) { + return -EFBIG; + } + + if (exact_size) { + new_l1_size = min_size; + } else { + /* Bump size up to reduce the number of times we have to grow */ + new_l1_size = s->l1_size; + if (new_l1_size == 0) { + new_l1_size = 1; + } + while (min_size > new_l1_size) { + new_l1_size = (new_l1_size * 3 + 1) / 2; + } + } + + if (new_l1_size > INT_MAX / sizeof(uint64_t)) { + return -EFBIG; + } + +#ifdef DEBUG_ALLOC2 + fprintf(stderr, "grow l1_table from %d to %" PRId64 "\n", + s->l1_size, new_l1_size); +#endif + + new_l1_size2 = sizeof(uint64_t) * new_l1_size; + new_l1_table = qemu_try_blockalign(bs->file, + align_offset(new_l1_size2, 512)); + if (new_l1_table == NULL) { + return -ENOMEM; + } + memset(new_l1_table, 0, 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_vfree(new_l1_table); + return new_l1_table_offset; + } + + ret = qcow2_cache_flush(bs, s->refcount_block_cache); + if (ret < 0) { + goto fail; + } + + /* the L1 position has not yet been updated, so these clusters must + * indeed be completely free */ + ret = qcow2_pre_write_overlap_check(bs, 0, new_l1_table_offset, + new_l1_size2); + if (ret < 0) { + goto fail; + } + + 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); + stq_be_p(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_vfree(s->l1_table); + old_l1_table_offset = s->l1_table_offset; + s->l1_table_offset = new_l1_table_offset; + s->l1_table = new_l1_table; + old_l1_size = s->l1_size; + s->l1_size = new_l1_size; + qcow2_free_clusters(bs, old_l1_table_offset, old_l1_size * sizeof(uint64_t), + QCOW2_DISCARD_OTHER); + return 0; + fail: + qemu_vfree(new_l1_table); + qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2, + QCOW2_DISCARD_OTHER); + return ret; +} + +/* + * 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 ret; + + ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, (void**) l2_table); + + return ret; +} + +/* + * 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) +int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index) +{ + BDRVQcowState *s = bs->opaque; + uint64_t buf[L1_ENTRIES_PER_SECTOR] = { 0 }; + 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 && l1_start_index + i < s->l1_size; + i++) + { + buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]); + } + + ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1, + s->l1_table_offset + 8 * l1_start_index, sizeof(buf)); + if (ret < 0) { + return ret; + } + + 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; + uint64_t old_l2_offset; + uint64_t *l2_table = NULL; + int64_t l2_offset; + int ret; + + old_l2_offset = s->l1_table[l1_index]; + + trace_qcow2_l2_allocate(bs, l1_index); + + /* allocate a new l2 entry */ + + l2_offset = qcow2_alloc_clusters(bs, s->l2_size * sizeof(uint64_t)); + if (l2_offset < 0) { + ret = l2_offset; + goto fail; + } + + ret = qcow2_cache_flush(bs, s->refcount_block_cache); + if (ret < 0) { + goto fail; + } + + /* allocate a new entry in the l2 cache */ + + trace_qcow2_l2_allocate_get_empty(bs, l1_index); + ret = qcow2_cache_get_empty(bs, s->l2_table_cache, l2_offset, (void**) table); + if (ret < 0) { + goto fail; + } + + l2_table = *table; + + if ((old_l2_offset & L1E_OFFSET_MASK) == 0) { + /* if there was no old l2 table, clear the new table */ + memset(l2_table, 0, s->l2_size * sizeof(uint64_t)); + } else { + uint64_t* old_table; + + /* if there was an old l2 table, read it from the disk */ + BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ); + ret = qcow2_cache_get(bs, s->l2_table_cache, + old_l2_offset & L1E_OFFSET_MASK, + (void**) &old_table); + if (ret < 0) { + goto fail; + } + + memcpy(l2_table, old_table, s->cluster_size); + + qcow2_cache_put(bs, s->l2_table_cache, (void **) &old_table); + } + + /* write the l2 table to the file */ + BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE); + + trace_qcow2_l2_allocate_write_l2(bs, l1_index); + qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table); + ret = qcow2_cache_flush(bs, s->l2_table_cache); + if (ret < 0) { + goto fail; + } + + /* update the L1 entry */ + trace_qcow2_l2_allocate_write_l1(bs, l1_index); + s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED; + ret = qcow2_write_l1_entry(bs, l1_index); + if (ret < 0) { + goto fail; + } + + *table = l2_table; + trace_qcow2_l2_allocate_done(bs, l1_index, 0); + return 0; + +fail: + trace_qcow2_l2_allocate_done(bs, l1_index, ret); + if (l2_table != NULL) { + qcow2_cache_put(bs, s->l2_table_cache, (void**) table); + } + s->l1_table[l1_index] = old_l2_offset; + if (l2_offset > 0) { + qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t), + QCOW2_DISCARD_ALWAYS); + } + return ret; +} + +/* + * Checks how many clusters in a given L2 table are contiguous in the image + * file. As soon as one of the flags in the bitmask stop_flags changes compared + * to the first cluster, the search is stopped and the cluster is not counted + * as contiguous. (This allows it, for example, to stop at the first compressed + * cluster which may require a different handling) + */ +static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size, + uint64_t *l2_table, uint64_t stop_flags) +{ + int i; + uint64_t mask = stop_flags | L2E_OFFSET_MASK | QCOW_OFLAG_COMPRESSED; + uint64_t first_entry = be64_to_cpu(l2_table[0]); + uint64_t offset = first_entry & mask; + + if (!offset) + return 0; + + assert(qcow2_get_cluster_type(first_entry) != QCOW2_CLUSTER_COMPRESSED); + + for (i = 0; i < nb_clusters; i++) { + uint64_t l2_entry = be64_to_cpu(l2_table[i]) & mask; + if (offset + (uint64_t) i * cluster_size != l2_entry) { + break; + } + } + + return i; +} + +static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t *l2_table) +{ + int i; + + for (i = 0; i < nb_clusters; i++) { + int type = qcow2_get_cluster_type(be64_to_cpu(l2_table[i])); + + if (type != QCOW2_CLUSTER_UNALLOCATED) { + break; + } + } + + return i; +} + +/* The crypt function is compatible with the linux cryptoloop + algorithm for < 4 GB images. NOTE: out_buf == in_buf is + supported */ +int qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num, + uint8_t *out_buf, const uint8_t *in_buf, + int nb_sectors, bool enc, + Error **errp) +{ + union { + uint64_t ll[2]; + uint8_t b[16]; + } ivec; + int i; + int ret; + + for(i = 0; i < nb_sectors; i++) { + ivec.ll[0] = cpu_to_le64(sector_num); + ivec.ll[1] = 0; + if (qcrypto_cipher_setiv(s->cipher, + ivec.b, G_N_ELEMENTS(ivec.b), + errp) < 0) { + return -1; + } + if (enc) { + ret = qcrypto_cipher_encrypt(s->cipher, + in_buf, + out_buf, + 512, + errp); + } else { + ret = qcrypto_cipher_decrypt(s->cipher, + in_buf, + out_buf, + 512, + errp); + } + if (ret < 0) { + return -1; + } + sector_num++; + in_buf += 512; + out_buf += 512; + } + return 0; +} + +static int coroutine_fn copy_sectors(BlockDriverState *bs, + uint64_t start_sect, + uint64_t cluster_offset, + int n_start, int n_end) +{ + BDRVQcowState *s = bs->opaque; + QEMUIOVector qiov; + struct iovec iov; + int n, ret; + + n = n_end - n_start; + if (n <= 0) { + return 0; + } + + iov.iov_len = n * BDRV_SECTOR_SIZE; + iov.iov_base = qemu_try_blockalign(bs, iov.iov_len); + if (iov.iov_base == NULL) { + return -ENOMEM; + } + + qemu_iovec_init_external(&qiov, &iov, 1); + + BLKDBG_EVENT(bs->file, BLKDBG_COW_READ); + + if (!bs->drv) { + ret = -ENOMEDIUM; + goto out; + } + + /* Call .bdrv_co_readv() directly instead of using the public block-layer + * interface. This avoids double I/O throttling and request tracking, + * which can lead to deadlock when block layer copy-on-read is enabled. + */ + ret = bs->drv->bdrv_co_readv(bs, start_sect + n_start, n, &qiov); + if (ret < 0) { + goto out; + } + + if (bs->encrypted) { + Error *err = NULL; + assert(s->cipher); + if (qcow2_encrypt_sectors(s, start_sect + n_start, + iov.iov_base, iov.iov_base, n, + true, &err) < 0) { + ret = -EIO; + error_free(err); + goto out; + } + } + + ret = qcow2_pre_write_overlap_check(bs, 0, + cluster_offset + n_start * BDRV_SECTOR_SIZE, n * BDRV_SECTOR_SIZE); + if (ret < 0) { + goto out; + } + + BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE); + ret = bdrv_co_writev(bs->file, (cluster_offset >> 9) + n_start, n, &qiov); + if (ret < 0) { + goto out; + } + + ret = 0; +out: + qemu_vfree(iov.iov_base); + return ret; +} + + +/* + * 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 sectors we'd like to + * access following offset. + * + * on exit, *num is the number of contiguous sectors we can read. + * + * Returns the cluster type (QCOW2_CLUSTER_*) on success, -errno in error + * cases. + */ +int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, + int *num, uint64_t *cluster_offset) +{ + BDRVQcowState *s = bs->opaque; + unsigned int l2_index; + uint64_t l1_index, 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) { + ret = QCOW2_CLUSTER_UNALLOCATED; + goto out; + } + + l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; + if (!l2_offset) { + ret = QCOW2_CLUSTER_UNALLOCATED; + goto out; + } + + if (offset_into_cluster(s, l2_offset)) { + qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64 + " unaligned (L1 index: %#" PRIx64 ")", + l2_offset, l1_index); + return -EIO; + } + + /* load the l2 table in memory */ + + 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); + + ret = qcow2_get_cluster_type(*cluster_offset); + switch (ret) { + case QCOW2_CLUSTER_COMPRESSED: + /* Compressed clusters can only be processed one by one */ + c = 1; + *cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK; + break; + case QCOW2_CLUSTER_ZERO: + if (s->qcow_version < 3) { + qcow2_signal_corruption(bs, true, -1, -1, "Zero cluster entry found" + " in pre-v3 image (L2 offset: %#" PRIx64 + ", L2 index: %#x)", l2_offset, l2_index); + ret = -EIO; + goto fail; + } + c = count_contiguous_clusters(nb_clusters, s->cluster_size, + &l2_table[l2_index], QCOW_OFLAG_ZERO); + *cluster_offset = 0; + break; + case QCOW2_CLUSTER_UNALLOCATED: + /* how many empty clusters ? */ + c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]); + *cluster_offset = 0; + break; + case QCOW2_CLUSTER_NORMAL: + /* how many allocated clusters ? */ + c = count_contiguous_clusters(nb_clusters, s->cluster_size, + &l2_table[l2_index], QCOW_OFLAG_ZERO); + *cluster_offset &= L2E_OFFSET_MASK; + if (offset_into_cluster(s, *cluster_offset)) { + qcow2_signal_corruption(bs, true, -1, -1, "Data cluster offset %#" + PRIx64 " unaligned (L2 offset: %#" PRIx64 + ", L2 index: %#x)", *cluster_offset, + l2_offset, l2_index); + ret = -EIO; + goto fail; + } + break; + default: + abort(); + } + + qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); + + nb_available = (c * s->cluster_sectors); + +out: + if (nb_available > nb_needed) + nb_available = nb_needed; + + *num = nb_available - index_in_cluster; + + return ret; + +fail: + qcow2_cache_put(bs, s->l2_table_cache, (void **)&l2_table); + return ret; +} + +/* + * 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, + int *new_l2_index) +{ + BDRVQcowState *s = bs->opaque; + unsigned int l2_index; + uint64_t l1_index, 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, false); + if (ret < 0) { + return ret; + } + } + + assert(l1_index < s->l1_size); + l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; + if (offset_into_cluster(s, l2_offset)) { + qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64 + " unaligned (L1 index: %#" PRIx64 ")", + l2_offset, l1_index); + return -EIO; + } + + /* seek the l2 table of the given l2 offset */ + + if (s->l1_table[l1_index] & QCOW_OFLAG_COPIED) { + /* load the l2 table in memory */ + ret = l2_load(bs, l2_offset, &l2_table); + if (ret < 0) { + return ret; + } + } else { + /* First allocate a new L2 table (and do COW if needed) */ + ret = l2_allocate(bs, l1_index, &l2_table); + if (ret < 0) { + return ret; + } + + /* Then decrease the refcount of the old table */ + if (l2_offset) { + qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t), + QCOW2_DISCARD_OTHER); + } + } + + /* 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_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_table; + int64_t cluster_offset; + int nb_csectors; + + ret = get_cluster_table(bs, offset, &l2_table, &l2_index); + if (ret < 0) { + return 0; + } + + /* Compression can't overwrite anything. Fail if the cluster was already + * allocated. */ + cluster_offset = be64_to_cpu(l2_table[l2_index]); + if (cluster_offset & L2E_OFFSET_MASK) { + qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); + return 0; + } + + cluster_offset = qcow2_alloc_bytes(bs, compressed_size); + if (cluster_offset < 0) { + qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); + 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); + qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table); + l2_table[l2_index] = cpu_to_be64(cluster_offset); + qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table); + + return cluster_offset; +} + +static int perform_cow(BlockDriverState *bs, QCowL2Meta *m, Qcow2COWRegion *r) +{ + BDRVQcowState *s = bs->opaque; + int ret; + + if (r->nb_sectors == 0) { + return 0; + } + + qemu_co_mutex_unlock(&s->lock); + ret = copy_sectors(bs, m->offset / BDRV_SECTOR_SIZE, m->alloc_offset, + r->offset / BDRV_SECTOR_SIZE, + r->offset / BDRV_SECTOR_SIZE + r->nb_sectors); + qemu_co_mutex_lock(&s->lock); + + if (ret < 0) { + return ret; + } + + /* + * Before we update the L2 table to actually point to the new cluster, we + * need to be sure that the refcounts have been increased and COW was + * handled. + */ + qcow2_cache_depends_on_flush(s->l2_table_cache); + + 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, *l2_table; + uint64_t cluster_offset = m->alloc_offset; + + trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters); + assert(m->nb_clusters > 0); + + old_cluster = g_try_new(uint64_t, m->nb_clusters); + if (old_cluster == NULL) { + ret = -ENOMEM; + goto err; + } + + /* copy content of unmodified sectors */ + ret = perform_cow(bs, m, &m->cow_start); + if (ret < 0) { + goto err; + } + + ret = perform_cow(bs, m, &m->cow_end); + if (ret < 0) { + goto err; + } + + /* Update L2 table. */ + if (s->use_lazy_refcounts) { + qcow2_mark_dirty(bs); + } + if (qcow2_need_accurate_refcounts(s)) { + qcow2_cache_set_dependency(bs, s->l2_table_cache, + s->refcount_block_cache); + } + + ret = get_cluster_table(bs, m->offset, &l2_table, &l2_index); + if (ret < 0) { + goto err; + } + qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table); + + assert(l2_index + m->nb_clusters <= s->l2_size); + 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); + } + + + qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table); + + /* + * If this was a COW, we need to decrease the refcount of the old cluster. + * Also flush bs->file to get the right order for L2 and refcount update. + * + * Don't discard clusters that reach a refcount of 0 (e.g. compressed + * clusters), the next write will reuse them anyway. + */ + if (j != 0) { + for (i = 0; i < j; i++) { + qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1, + QCOW2_DISCARD_NEVER); + } + } + + ret = 0; +err: + g_free(old_cluster); + return ret; + } + +/* + * Returns the number of contiguous clusters that can be used for an allocating + * write, but require COW to be performed (this includes yet unallocated space, + * which must copy from the backing file) + */ +static int count_cow_clusters(BDRVQcowState *s, int nb_clusters, + uint64_t *l2_table, int l2_index) +{ + int i; + + for (i = 0; i < nb_clusters; i++) { + uint64_t l2_entry = be64_to_cpu(l2_table[l2_index + i]); + int cluster_type = qcow2_get_cluster_type(l2_entry); + + switch(cluster_type) { + case QCOW2_CLUSTER_NORMAL: + if (l2_entry & QCOW_OFLAG_COPIED) { + goto out; + } + break; + case QCOW2_CLUSTER_UNALLOCATED: + case QCOW2_CLUSTER_COMPRESSED: + case QCOW2_CLUSTER_ZERO: + break; + default: + abort(); + } + } + +out: + assert(i <= nb_clusters); + return 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. + * + * Returns: + * 0 if there was no dependency. *cur_bytes indicates the number of + * bytes from guest_offset that can be read before the next + * dependency must be processed (or the request is complete) + * + * -EAGAIN if we had to wait for another request, previously gathered + * information on cluster allocation may be invalid now. The caller + * must start over anyway, so consider *cur_bytes undefined. + */ +static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset, + uint64_t *cur_bytes, QCowL2Meta **m) +{ + BDRVQcowState *s = bs->opaque; + QCowL2Meta *old_alloc; + uint64_t bytes = *cur_bytes; + + QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) { + + uint64_t start = guest_offset; + uint64_t end = start + bytes; + uint64_t old_start = l2meta_cow_start(old_alloc); + uint64_t old_end = l2meta_cow_end(old_alloc); + + if (end <= old_start || start >= old_end) { + /* No intersection */ + } else { + if (start < old_start) { + /* Stop at the start of a running allocation */ + bytes = old_start - start; + } else { + bytes = 0; + } + + /* Stop if already an l2meta exists. After yielding, it wouldn't + * be valid any more, so we'd have to clean up the old L2Metas + * and deal with requests depending on them before starting to + * gather new ones. Not worth the trouble. */ + if (bytes == 0 && *m) { + *cur_bytes = 0; + return 0; + } + + if (bytes == 0) { + /* Wait for the dependency to complete. We need to recheck + * the free/allocated clusters when we continue. */ + qemu_co_mutex_unlock(&s->lock); + qemu_co_queue_wait(&old_alloc->dependent_requests); + qemu_co_mutex_lock(&s->lock); + return -EAGAIN; + } + } + } + + /* Make sure that existing clusters and new allocations are only used up to + * the next dependency if we shortened the request above */ + *cur_bytes = bytes; + + return 0; +} + +/* + * Checks how many already allocated clusters that don't require a copy on + * write there are at the given guest_offset (up to *bytes). If + * *host_offset is not zero, only physically contiguous clusters beginning at + * this host offset are counted. + * + * Note that guest_offset may not be cluster aligned. In this case, the + * returned *host_offset points to exact byte referenced by guest_offset and + * therefore isn't cluster aligned as well. + * + * Returns: + * 0: if no allocated clusters are available at the given offset. + * *bytes is normally unchanged. It is set to 0 if the cluster + * is allocated and doesn't need COW, but doesn't have the right + * physical offset. + * + * 1: if allocated clusters that don't require a COW are available at + * the requested offset. *bytes may have decreased and describes + * the length of the area that can be written to. + * + * -errno: in error cases + */ +static int handle_copied(BlockDriverState *bs, uint64_t guest_offset, + uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m) +{ + BDRVQcowState *s = bs->opaque; + int l2_index; + uint64_t cluster_offset; + uint64_t *l2_table; + unsigned int nb_clusters; + unsigned int keep_clusters; + int ret; + + trace_qcow2_handle_copied(qemu_coroutine_self(), guest_offset, *host_offset, + *bytes); + + assert(*host_offset == 0 || offset_into_cluster(s, guest_offset) + == offset_into_cluster(s, *host_offset)); + + /* + * Calculate the number of clusters to look for. We stop at L2 table + * boundaries to keep things simple. + */ + nb_clusters = + size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes); + + l2_index = offset_to_l2_index(s, guest_offset); + nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); + + /* Find L2 entry for the first involved cluster */ + ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index); + if (ret < 0) { + return ret; + } + + cluster_offset = be64_to_cpu(l2_table[l2_index]); + + /* Check how many clusters are already allocated and don't need COW */ + if (qcow2_get_cluster_type(cluster_offset) == QCOW2_CLUSTER_NORMAL + && (cluster_offset & QCOW_OFLAG_COPIED)) + { + /* If a specific host_offset is required, check it */ + bool offset_matches = + (cluster_offset & L2E_OFFSET_MASK) == *host_offset; + + if (offset_into_cluster(s, cluster_offset & L2E_OFFSET_MASK)) { + qcow2_signal_corruption(bs, true, -1, -1, "Data cluster offset " + "%#llx unaligned (guest offset: %#" PRIx64 + ")", cluster_offset & L2E_OFFSET_MASK, + guest_offset); + ret = -EIO; + goto out; + } + + if (*host_offset != 0 && !offset_matches) { + *bytes = 0; + ret = 0; + goto out; + } + + /* We keep all QCOW_OFLAG_COPIED clusters */ + keep_clusters = + count_contiguous_clusters(nb_clusters, s->cluster_size, + &l2_table[l2_index], + QCOW_OFLAG_COPIED | QCOW_OFLAG_ZERO); + assert(keep_clusters <= nb_clusters); + + *bytes = MIN(*bytes, + keep_clusters * s->cluster_size + - offset_into_cluster(s, guest_offset)); + + ret = 1; + } else { + ret = 0; + } + + /* Cleanup */ +out: + qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table); + + /* Only return a host offset if we actually made progress. Otherwise we + * would make requirements for handle_alloc() that it can't fulfill */ + if (ret > 0) { + *host_offset = (cluster_offset & L2E_OFFSET_MASK) + + offset_into_cluster(s, guest_offset); + } + + return ret; +} + +/* + * Allocates new clusters for the given guest_offset. + * + * At most *nb_clusters are allocated, and on return *nb_clusters is updated to + * contain the number of clusters that have been allocated and are contiguous + * in the image file. + * + * If *host_offset is non-zero, it specifies the offset in the image file at + * which the new clusters must start. *nb_clusters can be 0 on return in this + * case if the cluster at host_offset is already in use. If *host_offset is + * zero, the clusters can be allocated anywhere in the image file. + * + * *host_offset is updated to contain the offset into the image file at which + * the first allocated cluster starts. + * + * Return 0 on success and -errno in error cases. -EAGAIN means that the + * function has been waiting for another request and the allocation must be + * restarted, but the whole request should not be failed. + */ +static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset, + uint64_t *host_offset, unsigned int *nb_clusters) +{ + BDRVQcowState *s = bs->opaque; + + trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset, + *host_offset, *nb_clusters); + + /* Allocate new clusters */ + trace_qcow2_cluster_alloc_phys(qemu_coroutine_self()); + if (*host_offset == 0) { + int64_t cluster_offset = + qcow2_alloc_clusters(bs, *nb_clusters * s->cluster_size); + if (cluster_offset < 0) { + return cluster_offset; + } + *host_offset = cluster_offset; + return 0; + } else { + int ret = qcow2_alloc_clusters_at(bs, *host_offset, *nb_clusters); + if (ret < 0) { + return ret; + } + *nb_clusters = ret; + return 0; + } +} + +/* + * Allocates new clusters for an area that either is yet unallocated or needs a + * copy on write. If *host_offset is non-zero, clusters are only allocated if + * the new allocation can match the specified host offset. + * + * Note that guest_offset may not be cluster aligned. In this case, the + * returned *host_offset points to exact byte referenced by guest_offset and + * therefore isn't cluster aligned as well. + * + * Returns: + * 0: if no clusters could be allocated. *bytes is set to 0, + * *host_offset is left unchanged. + * + * 1: if new clusters were allocated. *bytes may be decreased if the + * new allocation doesn't cover all of the requested area. + * *host_offset is updated to contain the host offset of the first + * newly allocated cluster. + * + * -errno: in error cases + */ +static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset, + uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m) +{ + BDRVQcowState *s = bs->opaque; + int l2_index; + uint64_t *l2_table; + uint64_t entry; + unsigned int nb_clusters; + int ret; + + uint64_t alloc_cluster_offset; + + trace_qcow2_handle_alloc(qemu_coroutine_self(), guest_offset, *host_offset, + *bytes); + assert(*bytes > 0); + + /* + * Calculate the number of clusters to look for. We stop at L2 table + * boundaries to keep things simple. + */ + nb_clusters = + size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes); + + l2_index = offset_to_l2_index(s, guest_offset); + nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); + + /* Find L2 entry for the first involved cluster */ + ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index); + if (ret < 0) { + return ret; + } + + entry = be64_to_cpu(l2_table[l2_index]); + + /* For the moment, overwrite compressed clusters one by one */ + if (entry & QCOW_OFLAG_COMPRESSED) { + nb_clusters = 1; + } else { + nb_clusters = count_cow_clusters(s, nb_clusters, l2_table, l2_index); + } + + /* This function is only called when there were no non-COW clusters, so if + * we can't find any unallocated or COW clusters either, something is + * wrong with our code. */ + assert(nb_clusters > 0); + + qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table); + + /* Allocate, if necessary at a given offset in the image file */ + alloc_cluster_offset = start_of_cluster(s, *host_offset); + ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset, + &nb_clusters); + if (ret < 0) { + goto fail; + } + + /* Can't extend contiguous allocation */ + if (nb_clusters == 0) { + *bytes = 0; + return 0; + } + + /* !*host_offset would overwrite the image header and is reserved for "no + * host offset preferred". If 0 was a valid host offset, it'd trigger the + * following overlap check; do that now to avoid having an invalid value in + * *host_offset. */ + if (!alloc_cluster_offset) { + ret = qcow2_pre_write_overlap_check(bs, 0, alloc_cluster_offset, + nb_clusters * s->cluster_size); + assert(ret < 0); + goto fail; + } + + /* + * Save info needed for meta data update. + * + * requested_sectors: Number of sectors from the start of the first + * newly allocated cluster to the end of the (possibly shortened + * before) write request. + * + * avail_sectors: Number of sectors from the start of the first + * newly allocated to the end of the last newly allocated cluster. + * + * nb_sectors: The number of sectors from the start of the first + * newly allocated cluster to the end of the area that the write + * request actually writes to (excluding COW at the end) + */ + int requested_sectors = + (*bytes + offset_into_cluster(s, guest_offset)) + >> BDRV_SECTOR_BITS; + int avail_sectors = nb_clusters + << (s->cluster_bits - BDRV_SECTOR_BITS); + int alloc_n_start = offset_into_cluster(s, guest_offset) + >> BDRV_SECTOR_BITS; + int nb_sectors = MIN(requested_sectors, avail_sectors); + QCowL2Meta *old_m = *m; + + *m = g_malloc0(sizeof(**m)); + + **m = (QCowL2Meta) { + .next = old_m, + + .alloc_offset = alloc_cluster_offset, + .offset = start_of_cluster(s, guest_offset), + .nb_clusters = nb_clusters, + .nb_available = nb_sectors, + + .cow_start = { + .offset = 0, + .nb_sectors = alloc_n_start, + }, + .cow_end = { + .offset = nb_sectors * BDRV_SECTOR_SIZE, + .nb_sectors = avail_sectors - nb_sectors, + }, + }; + qemu_co_queue_init(&(*m)->dependent_requests); + QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight); + + *host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset); + *bytes = MIN(*bytes, (nb_sectors * BDRV_SECTOR_SIZE) + - offset_into_cluster(s, guest_offset)); + assert(*bytes != 0); + + return 1; + +fail: + if (*m && (*m)->nb_clusters > 0) { + QLIST_REMOVE(*m, next_in_flight); + } + return ret; +} + +/* + * alloc_cluster_offset + * + * For a given offset on the virtual disk, find the 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 and + * 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. In this case, the other + * fields of m are valid and contain information about the first allocated + * cluster. + * + * If the request conflicts with another write request in flight, the coroutine + * is queued and will be reentered when the dependency has completed. + * + * Return 0 on success and -errno in error cases + */ +int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset, + int *num, uint64_t *host_offset, QCowL2Meta **m) +{ + BDRVQcowState *s = bs->opaque; + uint64_t start, remaining; + uint64_t cluster_offset; + uint64_t cur_bytes; + int ret; + + trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset, *num); + + assert((offset & ~BDRV_SECTOR_MASK) == 0); + +again: + start = offset; + remaining = (uint64_t)*num << BDRV_SECTOR_BITS; + cluster_offset = 0; + *host_offset = 0; + cur_bytes = 0; + *m = NULL; + + while (true) { + + if (!*host_offset) { + *host_offset = start_of_cluster(s, cluster_offset); + } + + assert(remaining >= cur_bytes); + + start += cur_bytes; + remaining -= cur_bytes; + cluster_offset += cur_bytes; + + if (remaining == 0) { + break; + } + + cur_bytes = remaining; + + /* + * Now start gathering as many contiguous clusters as possible: + * + * 1. Check for overlaps with in-flight allocations + * + * a) Overlap not in the first cluster -> shorten this request and + * let the caller handle the rest in its next loop iteration. + * + * b) Real overlaps of two requests. Yield and restart the search + * for contiguous clusters (the situation could have changed + * while we were sleeping) + * + * c) TODO: Request starts in the same cluster as the in-flight + * allocation ends. Shorten the COW of the in-fight allocation, + * set cluster_offset to write to the same cluster and set up + * the right synchronisation between the in-flight request and + * the new one. + */ + ret = handle_dependencies(bs, start, &cur_bytes, m); + if (ret == -EAGAIN) { + /* Currently handle_dependencies() doesn't yield if we already had + * an allocation. If it did, we would have to clean up the L2Meta + * structs before starting over. */ + assert(*m == NULL); + goto again; + } else if (ret < 0) { + return ret; + } else if (cur_bytes == 0) { + break; + } else { + /* handle_dependencies() may have decreased cur_bytes (shortened + * the allocations below) so that the next dependency is processed + * correctly during the next loop iteration. */ + } + + /* + * 2. Count contiguous COPIED clusters. + */ + ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m); + if (ret < 0) { + return ret; + } else if (ret) { + continue; + } else if (cur_bytes == 0) { + break; + } + + /* + * 3. If the request still hasn't completed, allocate new clusters, + * considering any cluster_offset of steps 1c or 2. + */ + ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m); + if (ret < 0) { + return ret; + } else if (ret) { + continue; + } else { + assert(cur_bytes == 0); + break; + } + } + + *num -= remaining >> BDRV_SECTOR_BITS; + assert(*num > 0); + assert(*host_offset != 0); + + 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 ret; + } + if (decompress_buffer(s->cluster_cache, s->cluster_size, + s->cluster_data + sector_offset, csize) < 0) { + return -EIO; + } + s->cluster_cache_offset = coffset; + } + return 0; +} + +/* + * This discards as many clusters of nb_clusters as possible at once (i.e. + * all clusters in the same L2 table) and returns the number of discarded + * clusters. + */ +static int discard_single_l2(BlockDriverState *bs, uint64_t offset, + unsigned int nb_clusters, enum qcow2_discard_type type, bool full_discard) +{ + BDRVQcowState *s = bs->opaque; + uint64_t *l2_table; + int l2_index; + int ret; + int i; + + ret = get_cluster_table(bs, offset, &l2_table, &l2_index); + if (ret < 0) { + return ret; + } + + /* Limit nb_clusters to one L2 table */ + nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); + + for (i = 0; i < nb_clusters; i++) { + uint64_t old_l2_entry; + + old_l2_entry = be64_to_cpu(l2_table[l2_index + i]); + + /* + * If full_discard is false, make sure that a discarded area reads back + * as zeroes for v3 images (we cannot do it for v2 without actually + * writing a zero-filled buffer). We can skip the operation if the + * cluster is already marked as zero, or if it's unallocated and we + * don't have a backing file. + * + * TODO We might want to use bdrv_get_block_status(bs) here, but we're + * holding s->lock, so that doesn't work today. + * + * If full_discard is true, the sector should not read back as zeroes, + * but rather fall through to the backing file. + */ + switch (qcow2_get_cluster_type(old_l2_entry)) { + case QCOW2_CLUSTER_UNALLOCATED: + if (full_discard || !bs->backing_hd) { + continue; + } + break; + + case QCOW2_CLUSTER_ZERO: + if (!full_discard) { + continue; + } + break; + + case QCOW2_CLUSTER_NORMAL: + case QCOW2_CLUSTER_COMPRESSED: + break; + + default: + abort(); + } + + /* First remove L2 entries */ + qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table); + if (!full_discard && s->qcow_version >= 3) { + l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO); + } else { + l2_table[l2_index + i] = cpu_to_be64(0); + } + + /* Then decrease the refcount */ + qcow2_free_any_clusters(bs, old_l2_entry, 1, type); + } + + qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table); + + return nb_clusters; +} + +int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset, + int nb_sectors, enum qcow2_discard_type type, bool full_discard) +{ + BDRVQcowState *s = bs->opaque; + uint64_t end_offset; + unsigned int nb_clusters; + int ret; + + end_offset = offset + (nb_sectors << BDRV_SECTOR_BITS); + + /* Round start up and end down */ + offset = align_offset(offset, s->cluster_size); + end_offset = start_of_cluster(s, end_offset); + + if (offset > end_offset) { + return 0; + } + + nb_clusters = size_to_clusters(s, end_offset - offset); + + s->cache_discards = true; + + /* Each L2 table is handled by its own loop iteration */ + while (nb_clusters > 0) { + ret = discard_single_l2(bs, offset, nb_clusters, type, full_discard); + if (ret < 0) { + goto fail; + } + + nb_clusters -= ret; + offset += (ret * s->cluster_size); + } + + ret = 0; +fail: + s->cache_discards = false; + qcow2_process_discards(bs, ret); + + return ret; +} + +/* + * This zeroes as many clusters of nb_clusters as possible at once (i.e. + * all clusters in the same L2 table) and returns the number of zeroed + * clusters. + */ +static int zero_single_l2(BlockDriverState *bs, uint64_t offset, + unsigned int nb_clusters) +{ + BDRVQcowState *s = bs->opaque; + uint64_t *l2_table; + int l2_index; + int ret; + int i; + + ret = get_cluster_table(bs, offset, &l2_table, &l2_index); + if (ret < 0) { + return ret; + } + + /* Limit nb_clusters to one L2 table */ + nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); + + for (i = 0; i < nb_clusters; i++) { + uint64_t old_offset; + + old_offset = be64_to_cpu(l2_table[l2_index + i]); + + /* Update L2 entries */ + qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table); + if (old_offset & QCOW_OFLAG_COMPRESSED) { + l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO); + qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST); + } else { + l2_table[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO); + } + } + + qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table); + + return nb_clusters; +} + +int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors) +{ + BDRVQcowState *s = bs->opaque; + unsigned int nb_clusters; + int ret; + + /* The zero flag is only supported by version 3 and newer */ + if (s->qcow_version < 3) { + return -ENOTSUP; + } + + /* Each L2 table is handled by its own loop iteration */ + nb_clusters = size_to_clusters(s, nb_sectors << BDRV_SECTOR_BITS); + + s->cache_discards = true; + + while (nb_clusters > 0) { + ret = zero_single_l2(bs, offset, nb_clusters); + if (ret < 0) { + goto fail; + } + + nb_clusters -= ret; + offset += (ret * s->cluster_size); + } + + ret = 0; +fail: + s->cache_discards = false; + qcow2_process_discards(bs, ret); + + return ret; +} + +/* + * Expands all zero clusters in a specific L1 table (or deallocates them, for + * non-backed non-pre-allocated zero clusters). + * + * l1_entries and *visited_l1_entries are used to keep track of progress for + * status_cb(). l1_entries contains the total number of L1 entries and + * *visited_l1_entries counts all visited L1 entries. + */ +static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table, + int l1_size, int64_t *visited_l1_entries, + int64_t l1_entries, + BlockDriverAmendStatusCB *status_cb) +{ + BDRVQcowState *s = bs->opaque; + bool is_active_l1 = (l1_table == s->l1_table); + uint64_t *l2_table = NULL; + int ret; + int i, j; + + if (!is_active_l1) { + /* inactive L2 tables require a buffer to be stored in when loading + * them from disk */ + l2_table = qemu_try_blockalign(bs->file, s->cluster_size); + if (l2_table == NULL) { + return -ENOMEM; + } + } + + for (i = 0; i < l1_size; i++) { + uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK; + bool l2_dirty = false; + uint64_t l2_refcount; + + if (!l2_offset) { + /* unallocated */ + (*visited_l1_entries)++; + if (status_cb) { + status_cb(bs, *visited_l1_entries, l1_entries); + } + continue; + } + + if (offset_into_cluster(s, l2_offset)) { + qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" + PRIx64 " unaligned (L1 index: %#x)", + l2_offset, i); + ret = -EIO; + goto fail; + } + + if (is_active_l1) { + /* get active L2 tables from cache */ + ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, + (void **)&l2_table); + } else { + /* load inactive L2 tables from disk */ + ret = bdrv_read(bs->file, l2_offset / BDRV_SECTOR_SIZE, + (void *)l2_table, s->cluster_sectors); + } + if (ret < 0) { + goto fail; + } + + ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits, + &l2_refcount); + if (ret < 0) { + goto fail; + } + + for (j = 0; j < s->l2_size; j++) { + uint64_t l2_entry = be64_to_cpu(l2_table[j]); + int64_t offset = l2_entry & L2E_OFFSET_MASK; + int cluster_type = qcow2_get_cluster_type(l2_entry); + bool preallocated = offset != 0; + + if (cluster_type != QCOW2_CLUSTER_ZERO) { + continue; + } + + if (!preallocated) { + if (!bs->backing_hd) { + /* not backed; therefore we can simply deallocate the + * cluster */ + l2_table[j] = 0; + l2_dirty = true; + continue; + } + + offset = qcow2_alloc_clusters(bs, s->cluster_size); + if (offset < 0) { + ret = offset; + goto fail; + } + + if (l2_refcount > 1) { + /* For shared L2 tables, set the refcount accordingly (it is + * already 1 and needs to be l2_refcount) */ + ret = qcow2_update_cluster_refcount(bs, + offset >> s->cluster_bits, + refcount_diff(1, l2_refcount), false, + QCOW2_DISCARD_OTHER); + if (ret < 0) { + qcow2_free_clusters(bs, offset, s->cluster_size, + QCOW2_DISCARD_OTHER); + goto fail; + } + } + } + + if (offset_into_cluster(s, offset)) { + qcow2_signal_corruption(bs, true, -1, -1, "Data cluster offset " + "%#" PRIx64 " unaligned (L2 offset: %#" + PRIx64 ", L2 index: %#x)", offset, + l2_offset, j); + if (!preallocated) { + qcow2_free_clusters(bs, offset, s->cluster_size, + QCOW2_DISCARD_ALWAYS); + } + ret = -EIO; + goto fail; + } + + ret = qcow2_pre_write_overlap_check(bs, 0, offset, s->cluster_size); + if (ret < 0) { + if (!preallocated) { + qcow2_free_clusters(bs, offset, s->cluster_size, + QCOW2_DISCARD_ALWAYS); + } + goto fail; + } + + ret = bdrv_write_zeroes(bs->file, offset / BDRV_SECTOR_SIZE, + s->cluster_sectors, 0); + if (ret < 0) { + if (!preallocated) { + qcow2_free_clusters(bs, offset, s->cluster_size, + QCOW2_DISCARD_ALWAYS); + } + goto fail; + } + + if (l2_refcount == 1) { + l2_table[j] = cpu_to_be64(offset | QCOW_OFLAG_COPIED); + } else { + l2_table[j] = cpu_to_be64(offset); + } + l2_dirty = true; + } + + if (is_active_l1) { + if (l2_dirty) { + qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table); + qcow2_cache_depends_on_flush(s->l2_table_cache); + } + qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table); + } else { + if (l2_dirty) { + ret = qcow2_pre_write_overlap_check(bs, + QCOW2_OL_INACTIVE_L2 | QCOW2_OL_ACTIVE_L2, l2_offset, + s->cluster_size); + if (ret < 0) { + goto fail; + } + + ret = bdrv_write(bs->file, l2_offset / BDRV_SECTOR_SIZE, + (void *)l2_table, s->cluster_sectors); + if (ret < 0) { + goto fail; + } + } + } + + (*visited_l1_entries)++; + if (status_cb) { + status_cb(bs, *visited_l1_entries, l1_entries); + } + } + + ret = 0; + +fail: + if (l2_table) { + if (!is_active_l1) { + qemu_vfree(l2_table); + } else { + qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table); + } + } + return ret; +} + +/* + * For backed images, expands all zero clusters on the image. For non-backed + * images, deallocates all non-pre-allocated zero clusters (and claims the + * allocation for pre-allocated ones). This is important for downgrading to a + * qcow2 version which doesn't yet support metadata zero clusters. + */ +int qcow2_expand_zero_clusters(BlockDriverState *bs, + BlockDriverAmendStatusCB *status_cb) +{ + BDRVQcowState *s = bs->opaque; + uint64_t *l1_table = NULL; + int64_t l1_entries = 0, visited_l1_entries = 0; + int ret; + int i, j; + + if (status_cb) { + l1_entries = s->l1_size; + for (i = 0; i < s->nb_snapshots; i++) { + l1_entries += s->snapshots[i].l1_size; + } + } + + ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size, + &visited_l1_entries, l1_entries, + status_cb); + if (ret < 0) { + goto fail; + } + + /* Inactive L1 tables may point to active L2 tables - therefore it is + * necessary to flush the L2 table cache before trying to access the L2 + * tables pointed to by inactive L1 entries (else we might try to expand + * zero clusters that have already been expanded); furthermore, it is also + * necessary to empty the L2 table cache, since it may contain tables which + * are now going to be modified directly on disk, bypassing the cache. + * qcow2_cache_empty() does both for us. */ + ret = qcow2_cache_empty(bs, s->l2_table_cache); + if (ret < 0) { + goto fail; + } + + for (i = 0; i < s->nb_snapshots; i++) { + int l1_sectors = (s->snapshots[i].l1_size * sizeof(uint64_t) + + BDRV_SECTOR_SIZE - 1) / BDRV_SECTOR_SIZE; + + l1_table = g_realloc(l1_table, l1_sectors * BDRV_SECTOR_SIZE); + + ret = bdrv_read(bs->file, s->snapshots[i].l1_table_offset / + BDRV_SECTOR_SIZE, (void *)l1_table, l1_sectors); + if (ret < 0) { + goto fail; + } + + for (j = 0; j < s->snapshots[i].l1_size; j++) { + be64_to_cpus(&l1_table[j]); + } + + ret = expand_zero_clusters_in_l1(bs, l1_table, s->snapshots[i].l1_size, + &visited_l1_entries, l1_entries, + status_cb); + if (ret < 0) { + goto fail; + } + } + + ret = 0; + +fail: + g_free(l1_table); + return ret; +} |