/* * Block driver for the QCOW version 2 format * * Copyright (c) 2004-2006 Fabrice Bellard * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include "qemu/osdep.h" #include #include "qapi/error.h" #include "qcow2.h" #include "qemu/bswap.h" #include "trace.h" int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t exact_size) { BDRVQcow2State *s = bs->opaque; int new_l1_size, i, ret; if (exact_size >= s->l1_size) { return 0; } new_l1_size = exact_size; #ifdef DEBUG_ALLOC2 fprintf(stderr, "shrink l1_table from %d to %d\n", s->l1_size, new_l1_size); #endif BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_WRITE_TABLE); ret = bdrv_pwrite_zeroes(bs->file, s->l1_table_offset + new_l1_size * L1E_SIZE, (s->l1_size - new_l1_size) * L1E_SIZE, 0); if (ret < 0) { goto fail; } ret = bdrv_flush(bs->file->bs); if (ret < 0) { goto fail; } BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_FREE_L2_CLUSTERS); for (i = s->l1_size - 1; i > new_l1_size - 1; i--) { if ((s->l1_table[i] & L1E_OFFSET_MASK) == 0) { continue; } qcow2_free_clusters(bs, s->l1_table[i] & L1E_OFFSET_MASK, s->cluster_size, QCOW2_DISCARD_ALWAYS); s->l1_table[i] = 0; } return 0; fail: /* * If the write in the l1_table failed the image may contain a partially * overwritten l1_table. In this case it would be better to clear the * l1_table in memory to avoid possible image corruption. */ memset(s->l1_table + new_l1_size, 0, (s->l1_size - new_l1_size) * L1E_SIZE); return ret; } int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size, bool exact_size) { BDRVQcow2State *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 / L1E_SIZE) { 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 = DIV_ROUND_UP(new_l1_size * 3, 2); } } QEMU_BUILD_BUG_ON(QCOW_MAX_L1_SIZE > INT_MAX); if (new_l1_size > QCOW_MAX_L1_SIZE / L1E_SIZE) { 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 = L1E_SIZE * new_l1_size; new_l1_table = qemu_try_blockalign(bs->file->bs, new_l1_size2); if (new_l1_table == NULL) { return -ENOMEM; } memset(new_l1_table, 0, new_l1_size2); if (s->l1_size) { memcpy(new_l1_table, s->l1_table, s->l1_size * L1E_SIZE); } /* 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, false); 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); stl_be_p(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 * L1E_SIZE, 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 * * @bs: The BlockDriverState * @offset: A guest offset, used to calculate what slice of the L2 * table to load. * @l2_offset: Offset to the L2 table in the image file. * @l2_slice: Location to store the pointer to the L2 slice. * * Loads a L2 slice into memory (L2 slices are the parts of L2 tables * that are loaded by the qcow2 cache). If the slice is in the cache, * the cache is used; otherwise the L2 slice is loaded from the image * file. */ static int l2_load(BlockDriverState *bs, uint64_t offset, uint64_t l2_offset, uint64_t **l2_slice) { BDRVQcow2State *s = bs->opaque; int start_of_slice = l2_entry_size(s) * (offset_to_l2_index(s, offset) - offset_to_l2_slice_index(s, offset)); return qcow2_cache_get(bs, s->l2_table_cache, l2_offset + start_of_slice, (void **)l2_slice); } /* * Writes an L1 entry to disk (note that depending on the alignment * requirements this function may write more that just one entry in * order to prevent bdrv_pwrite from performing a read-modify-write) */ int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index) { BDRVQcow2State *s = bs->opaque; int l1_start_index; int i, ret; int bufsize = MAX(L1E_SIZE, MIN(bs->file->bs->bl.request_alignment, s->cluster_size)); int nentries = bufsize / L1E_SIZE; g_autofree uint64_t *buf = g_try_new0(uint64_t, nentries); if (buf == NULL) { return -ENOMEM; } l1_start_index = QEMU_ALIGN_DOWN(l1_index, nentries); for (i = 0; i < MIN(nentries, s->l1_size - l1_start_index); 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 + L1E_SIZE * l1_start_index, bufsize, false); if (ret < 0) { return ret; } BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE); ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset + L1E_SIZE * l1_start_index, buf, bufsize); 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) { BDRVQcow2State *s = bs->opaque; uint64_t old_l2_offset; uint64_t *l2_slice = NULL; unsigned slice, slice_size2, n_slices; 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 * l2_entry_size(s)); if (l2_offset < 0) { ret = l2_offset; goto fail; } /* The offset must fit in the offset field of the L1 table entry */ assert((l2_offset & L1E_OFFSET_MASK) == l2_offset); /* If we're allocating the table at offset 0 then something is wrong */ if (l2_offset == 0) { qcow2_signal_corruption(bs, true, -1, -1, "Preventing invalid " "allocation of L2 table at offset 0"); ret = -EIO; goto fail; } ret = qcow2_cache_flush(bs, s->refcount_block_cache); if (ret < 0) { goto fail; } /* allocate a new entry in the l2 cache */ slice_size2 = s->l2_slice_size * l2_entry_size(s); n_slices = s->cluster_size / slice_size2; trace_qcow2_l2_allocate_get_empty(bs, l1_index); for (slice = 0; slice < n_slices; slice++) { ret = qcow2_cache_get_empty(bs, s->l2_table_cache, l2_offset + slice * slice_size2, (void **) &l2_slice); if (ret < 0) { goto fail; } if ((old_l2_offset & L1E_OFFSET_MASK) == 0) { /* if there was no old l2 table, clear the new slice */ memset(l2_slice, 0, slice_size2); } else { uint64_t *old_slice; uint64_t old_l2_slice_offset = (old_l2_offset & L1E_OFFSET_MASK) + slice * slice_size2; /* if there was an old l2 table, read a slice from the disk */ BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ); ret = qcow2_cache_get(bs, s->l2_table_cache, old_l2_slice_offset, (void **) &old_slice); if (ret < 0) { goto fail; } memcpy(l2_slice, old_slice, slice_size2); qcow2_cache_put(s->l2_table_cache, (void **) &old_slice); } /* write the l2 slice 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(s->l2_table_cache, l2_slice); qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); } 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; } trace_qcow2_l2_allocate_done(bs, l1_index, 0); return 0; fail: trace_qcow2_l2_allocate_done(bs, l1_index, ret); if (l2_slice != NULL) { qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); } s->l1_table[l1_index] = old_l2_offset; if (l2_offset > 0) { qcow2_free_clusters(bs, l2_offset, s->l2_size * l2_entry_size(s), QCOW2_DISCARD_ALWAYS); } return ret; } /* * For a given L2 entry, count the number of contiguous subclusters of * the same type starting from @sc_from. Compressed clusters are * treated as if they were divided into subclusters of size * s->subcluster_size. * * Return the number of contiguous subclusters and set @type to the * subcluster type. * * If the L2 entry is invalid return -errno and set @type to * QCOW2_SUBCLUSTER_INVALID. */ static int qcow2_get_subcluster_range_type(BlockDriverState *bs, uint64_t l2_entry, uint64_t l2_bitmap, unsigned sc_from, QCow2SubclusterType *type) { BDRVQcow2State *s = bs->opaque; uint32_t val; *type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_from); if (*type == QCOW2_SUBCLUSTER_INVALID) { return -EINVAL; } else if (!has_subclusters(s) || *type == QCOW2_SUBCLUSTER_COMPRESSED) { return s->subclusters_per_cluster - sc_from; } switch (*type) { case QCOW2_SUBCLUSTER_NORMAL: val = l2_bitmap | QCOW_OFLAG_SUB_ALLOC_RANGE(0, sc_from); return cto32(val) - sc_from; case QCOW2_SUBCLUSTER_ZERO_PLAIN: case QCOW2_SUBCLUSTER_ZERO_ALLOC: val = (l2_bitmap | QCOW_OFLAG_SUB_ZERO_RANGE(0, sc_from)) >> 32; return cto32(val) - sc_from; case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN: case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: val = ((l2_bitmap >> 32) | l2_bitmap) & ~QCOW_OFLAG_SUB_ALLOC_RANGE(0, sc_from); return ctz32(val) - sc_from; default: g_assert_not_reached(); } } /* * Return the number of contiguous subclusters of the exact same type * in a given L2 slice, starting from cluster @l2_index, subcluster * @sc_index. Allocated subclusters are required to be contiguous in * the image file. * At most @nb_clusters are checked (note that this means clusters, * not subclusters). * Compressed clusters are always processed one by one but for the * purpose of this count they are treated as if they were divided into * subclusters of size s->subcluster_size. * On failure return -errno and update @l2_index to point to the * invalid entry. */ static int count_contiguous_subclusters(BlockDriverState *bs, int nb_clusters, unsigned sc_index, uint64_t *l2_slice, unsigned *l2_index) { BDRVQcow2State *s = bs->opaque; int i, count = 0; bool check_offset = false; uint64_t expected_offset = 0; QCow2SubclusterType expected_type = QCOW2_SUBCLUSTER_NORMAL, type; assert(*l2_index + nb_clusters <= s->l2_slice_size); for (i = 0; i < nb_clusters; i++) { unsigned first_sc = (i == 0) ? sc_index : 0; uint64_t l2_entry = get_l2_entry(s, l2_slice, *l2_index + i); uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, *l2_index + i); int ret = qcow2_get_subcluster_range_type(bs, l2_entry, l2_bitmap, first_sc, &type); if (ret < 0) { *l2_index += i; /* Point to the invalid entry */ return -EIO; } if (i == 0) { if (type == QCOW2_SUBCLUSTER_COMPRESSED) { /* Compressed clusters are always processed one by one */ return ret; } expected_type = type; expected_offset = l2_entry & L2E_OFFSET_MASK; check_offset = (type == QCOW2_SUBCLUSTER_NORMAL || type == QCOW2_SUBCLUSTER_ZERO_ALLOC || type == QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC); } else if (type != expected_type) { break; } else if (check_offset) { expected_offset += s->cluster_size; if (expected_offset != (l2_entry & L2E_OFFSET_MASK)) { break; } } count += ret; /* Stop if there are type changes before the end of the cluster */ if (first_sc + ret < s->subclusters_per_cluster) { break; } } return count; } static int coroutine_fn do_perform_cow_read(BlockDriverState *bs, uint64_t src_cluster_offset, unsigned offset_in_cluster, QEMUIOVector *qiov) { int ret; if (qiov->size == 0) { return 0; } BLKDBG_EVENT(bs->file, BLKDBG_COW_READ); if (!bs->drv) { return -ENOMEDIUM; } /* 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_preadv_part(bs, src_cluster_offset + offset_in_cluster, qiov->size, qiov, 0, 0); if (ret < 0) { return ret; } return 0; } static int coroutine_fn do_perform_cow_write(BlockDriverState *bs, uint64_t cluster_offset, unsigned offset_in_cluster, QEMUIOVector *qiov) { BDRVQcow2State *s = bs->opaque; int ret; if (qiov->size == 0) { return 0; } ret = qcow2_pre_write_overlap_check(bs, 0, cluster_offset + offset_in_cluster, qiov->size, true); if (ret < 0) { return ret; } BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE); ret = bdrv_co_pwritev(s->data_file, cluster_offset + offset_in_cluster, qiov->size, qiov, 0); if (ret < 0) { return ret; } return 0; } /* * get_host_offset * * For a given offset of the virtual disk find the equivalent host * offset in the qcow2 file and store it in *host_offset. Neither * offset needs to be aligned to a cluster boundary. * * If the cluster is unallocated then *host_offset will be 0. * If the cluster is compressed then *host_offset will contain the * complete compressed cluster descriptor. * * On entry, *bytes is the maximum number of contiguous bytes starting at * offset that we are interested in. * * On exit, *bytes is the number of bytes starting at offset that have the same * subcluster type and (if applicable) are stored contiguously in the image * file. The subcluster type is stored in *subcluster_type. * Compressed clusters are always processed one by one. * * Returns 0 on success, -errno in error cases. */ int qcow2_get_host_offset(BlockDriverState *bs, uint64_t offset, unsigned int *bytes, uint64_t *host_offset, QCow2SubclusterType *subcluster_type) { BDRVQcow2State *s = bs->opaque; unsigned int l2_index, sc_index; uint64_t l1_index, l2_offset, *l2_slice, l2_entry, l2_bitmap; int sc; unsigned int offset_in_cluster; uint64_t bytes_available, bytes_needed, nb_clusters; QCow2SubclusterType type; int ret; offset_in_cluster = offset_into_cluster(s, offset); bytes_needed = (uint64_t) *bytes + offset_in_cluster; /* compute how many bytes there are between the start of the cluster * containing offset and the end of the l2 slice that contains * the entry pointing to it */ bytes_available = ((uint64_t) (s->l2_slice_size - offset_to_l2_slice_index(s, offset))) << s->cluster_bits; if (bytes_needed > bytes_available) { bytes_needed = bytes_available; } *host_offset = 0; /* seek to the l2 offset in the l1 table */ l1_index = offset_to_l1_index(s, offset); if (l1_index >= s->l1_size) { type = QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN; goto out; } l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; if (!l2_offset) { type = QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN; 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 slice in memory */ ret = l2_load(bs, offset, l2_offset, &l2_slice); if (ret < 0) { return ret; } /* find the cluster offset for the given disk offset */ l2_index = offset_to_l2_slice_index(s, offset); sc_index = offset_to_sc_index(s, offset); l2_entry = get_l2_entry(s, l2_slice, l2_index); l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index); nb_clusters = size_to_clusters(s, bytes_needed); /* bytes_needed <= *bytes + offset_in_cluster, both of which are unsigned * integers; the minimum cluster size is 512, so this assertion is always * true */ assert(nb_clusters <= INT_MAX); type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index); if (s->qcow_version < 3 && (type == QCOW2_SUBCLUSTER_ZERO_PLAIN || type == QCOW2_SUBCLUSTER_ZERO_ALLOC)) { 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; } switch (type) { case QCOW2_SUBCLUSTER_INVALID: break; /* This is handled by count_contiguous_subclusters() below */ case QCOW2_SUBCLUSTER_COMPRESSED: if (has_data_file(bs)) { qcow2_signal_corruption(bs, true, -1, -1, "Compressed cluster " "entry found in image with external data " "file (L2 offset: %#" PRIx64 ", L2 index: " "%#x)", l2_offset, l2_index); ret = -EIO; goto fail; } *host_offset = l2_entry & L2E_COMPRESSED_OFFSET_SIZE_MASK; break; case QCOW2_SUBCLUSTER_ZERO_PLAIN: case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN: break; case QCOW2_SUBCLUSTER_ZERO_ALLOC: case QCOW2_SUBCLUSTER_NORMAL: case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: { uint64_t host_cluster_offset = l2_entry & L2E_OFFSET_MASK; *host_offset = host_cluster_offset + offset_in_cluster; if (offset_into_cluster(s, host_cluster_offset)) { qcow2_signal_corruption(bs, true, -1, -1, "Cluster allocation offset %#" PRIx64 " unaligned (L2 offset: %#" PRIx64 ", L2 index: %#x)", host_cluster_offset, l2_offset, l2_index); ret = -EIO; goto fail; } if (has_data_file(bs) && *host_offset != offset) { qcow2_signal_corruption(bs, true, -1, -1, "External data file host cluster offset %#" PRIx64 " does not match guest cluster " "offset: %#" PRIx64 ", L2 index: %#x)", host_cluster_offset, offset - offset_in_cluster, l2_index); ret = -EIO; goto fail; } break; } default: abort(); } sc = count_contiguous_subclusters(bs, nb_clusters, sc_index, l2_slice, &l2_index); if (sc < 0) { qcow2_signal_corruption(bs, true, -1, -1, "Invalid cluster entry found " " (L2 offset: %#" PRIx64 ", L2 index: %#x)", l2_offset, l2_index); ret = -EIO; goto fail; } qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); bytes_available = ((int64_t)sc + sc_index) << s->subcluster_bits; out: if (bytes_available > bytes_needed) { bytes_available = bytes_needed; } /* bytes_available <= bytes_needed <= *bytes + offset_in_cluster; * subtracting offset_in_cluster will therefore definitely yield something * not exceeding UINT_MAX */ assert(bytes_available - offset_in_cluster <= UINT_MAX); *bytes = bytes_available - offset_in_cluster; *subcluster_type = type; return 0; fail: qcow2_cache_put(s->l2_table_cache, (void **)&l2_slice); return ret; } /* * get_cluster_table * * for a given disk offset, load (and allocate if needed) * the appropriate slice of its l2 table. * * the cluster index in the l2 slice is 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_slice, int *new_l2_index) { BDRVQcow2State *s = bs->opaque; unsigned int l2_index; uint64_t l1_index, l2_offset; uint64_t *l2_slice = NULL; int ret; /* seek to the l2 offset in the l1 table */ l1_index = offset_to_l1_index(s, offset); 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; } if (!(s->l1_table[l1_index] & QCOW_OFLAG_COPIED)) { /* First allocate a new L2 table (and do COW if needed) */ ret = l2_allocate(bs, l1_index); 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 * l2_entry_size(s), QCOW2_DISCARD_OTHER); } /* Get the offset of the newly-allocated l2 table */ l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; assert(offset_into_cluster(s, l2_offset) == 0); } /* load the l2 slice in memory */ ret = l2_load(bs, offset, l2_offset, &l2_slice); if (ret < 0) { return ret; } /* find the cluster offset for the given disk offset */ l2_index = offset_to_l2_slice_index(s, offset); *new_l2_slice = l2_slice; *new_l2_index = l2_index; return 0; } /* * alloc_compressed_cluster_offset * * For a given offset on the virtual disk, allocate a new compressed cluster * and put the host offset of the cluster into *host_offset. If a cluster is * already allocated at the offset, return an error. * * Return 0 on success and -errno in error cases */ int qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs, uint64_t offset, int compressed_size, uint64_t *host_offset) { BDRVQcow2State *s = bs->opaque; int l2_index, ret; uint64_t *l2_slice; int64_t cluster_offset; int nb_csectors; if (has_data_file(bs)) { return 0; } ret = get_cluster_table(bs, offset, &l2_slice, &l2_index); if (ret < 0) { return ret; } /* Compression can't overwrite anything. Fail if the cluster was already * allocated. */ cluster_offset = get_l2_entry(s, l2_slice, l2_index); if (cluster_offset & L2E_OFFSET_MASK) { qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); return -EIO; } cluster_offset = qcow2_alloc_bytes(bs, compressed_size); if (cluster_offset < 0) { qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); return cluster_offset; } nb_csectors = (cluster_offset + compressed_size - 1) / QCOW2_COMPRESSED_SECTOR_SIZE - (cluster_offset / QCOW2_COMPRESSED_SECTOR_SIZE); /* The offset and size must fit in their fields of the L2 table entry */ assert((cluster_offset & s->cluster_offset_mask) == cluster_offset); assert((nb_csectors & s->csize_mask) == nb_csectors); 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(s->l2_table_cache, l2_slice); set_l2_entry(s, l2_slice, l2_index, cluster_offset); if (has_subclusters(s)) { set_l2_bitmap(s, l2_slice, l2_index, 0); } qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); *host_offset = cluster_offset & s->cluster_offset_mask; return 0; } static int perform_cow(BlockDriverState *bs, QCowL2Meta *m) { BDRVQcow2State *s = bs->opaque; Qcow2COWRegion *start = &m->cow_start; Qcow2COWRegion *end = &m->cow_end; unsigned buffer_size; unsigned data_bytes = end->offset - (start->offset + start->nb_bytes); bool merge_reads; uint8_t *start_buffer, *end_buffer; QEMUIOVector qiov; int ret; assert(start->nb_bytes <= UINT_MAX - end->nb_bytes); assert(start->nb_bytes + end->nb_bytes <= UINT_MAX - data_bytes); assert(start->offset + start->nb_bytes <= end->offset); if ((start->nb_bytes == 0 && end->nb_bytes == 0) || m->skip_cow) { return 0; } /* If we have to read both the start and end COW regions and the * middle region is not too large then perform just one read * operation */ merge_reads = start->nb_bytes && end->nb_bytes && data_bytes <= 16384; if (merge_reads) { buffer_size = start->nb_bytes + data_bytes + end->nb_bytes; } else { /* If we have to do two reads, add some padding in the middle * if necessary to make sure that the end region is optimally * aligned. */ size_t align = bdrv_opt_mem_align(bs); assert(align > 0 && align <= UINT_MAX); assert(QEMU_ALIGN_UP(start->nb_bytes, align) <= UINT_MAX - end->nb_bytes); buffer_size = QEMU_ALIGN_UP(start->nb_bytes, align) + end->nb_bytes; } /* Reserve a buffer large enough to store all the data that we're * going to read */ start_buffer = qemu_try_blockalign(bs, buffer_size); if (start_buffer == NULL) { return -ENOMEM; } /* The part of the buffer where the end region is located */ end_buffer = start_buffer + buffer_size - end->nb_bytes; qemu_iovec_init(&qiov, 2 + (m->data_qiov ? qemu_iovec_subvec_niov(m->data_qiov, m->data_qiov_offset, data_bytes) : 0)); qemu_co_mutex_unlock(&s->lock); /* First we read the existing data from both COW regions. We * either read the whole region in one go, or the start and end * regions separately. */ if (merge_reads) { qemu_iovec_add(&qiov, start_buffer, buffer_size); ret = do_perform_cow_read(bs, m->offset, start->offset, &qiov); } else { qemu_iovec_add(&qiov, start_buffer, start->nb_bytes); ret = do_perform_cow_read(bs, m->offset, start->offset, &qiov); if (ret < 0) { goto fail; } qemu_iovec_reset(&qiov); qemu_iovec_add(&qiov, end_buffer, end->nb_bytes); ret = do_perform_cow_read(bs, m->offset, end->offset, &qiov); } if (ret < 0) { goto fail; } /* Encrypt the data if necessary before writing it */ if (bs->encrypted) { ret = qcow2_co_encrypt(bs, m->alloc_offset + start->offset, m->offset + start->offset, start_buffer, start->nb_bytes); if (ret < 0) { goto fail; } ret = qcow2_co_encrypt(bs, m->alloc_offset + end->offset, m->offset + end->offset, end_buffer, end->nb_bytes); if (ret < 0) { goto fail; } } /* And now we can write everything. If we have the guest data we * can write everything in one single operation */ if (m->data_qiov) { qemu_iovec_reset(&qiov); if (start->nb_bytes) { qemu_iovec_add(&qiov, start_buffer, start->nb_bytes); } qemu_iovec_concat(&qiov, m->data_qiov, m->data_qiov_offset, data_bytes); if (end->nb_bytes) { qemu_iovec_add(&qiov, end_buffer, end->nb_bytes); } /* NOTE: we have a write_aio blkdebug event here followed by * a cow_write one in do_perform_cow_write(), but there's only * one single I/O operation */ BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO); ret = do_perform_cow_write(bs, m->alloc_offset, start->offset, &qiov); } else { /* If there's no guest data then write both COW regions separately */ qemu_iovec_reset(&qiov); qemu_iovec_add(&qiov, start_buffer, start->nb_bytes); ret = do_perform_cow_write(bs, m->alloc_offset, start->offset, &qiov); if (ret < 0) { goto fail; } qemu_iovec_reset(&qiov); qemu_iovec_add(&qiov, end_buffer, end->nb_bytes); ret = do_perform_cow_write(bs, m->alloc_offset, end->offset, &qiov); } fail: qemu_co_mutex_lock(&s->lock); /* * 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. */ if (ret == 0) { qcow2_cache_depends_on_flush(s->l2_table_cache); } qemu_vfree(start_buffer); qemu_iovec_destroy(&qiov); return ret; } int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) { BDRVQcow2State *s = bs->opaque; int i, j = 0, l2_index, ret; uint64_t *old_cluster, *l2_slice; 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); 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_slice, &l2_index); if (ret < 0) { goto err; } qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); assert(l2_index + m->nb_clusters <= s->l2_slice_size); assert(m->cow_end.offset + m->cow_end.nb_bytes <= m->nb_clusters << s->cluster_bits); for (i = 0; i < m->nb_clusters; i++) { uint64_t offset = cluster_offset + ((uint64_t)i << s->cluster_bits); /* 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 * perform_cow()), update l2 table with its cluster pointer and free * old cluster. This is what this loop does */ if (get_l2_entry(s, l2_slice, l2_index + i) != 0) { old_cluster[j++] = get_l2_entry(s, l2_slice, l2_index + i); } /* The offset must fit in the offset field of the L2 table entry */ assert((offset & L2E_OFFSET_MASK) == offset); set_l2_entry(s, l2_slice, l2_index + i, offset | QCOW_OFLAG_COPIED); /* Update bitmap with the subclusters that were just written */ if (has_subclusters(s) && !m->prealloc) { uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i); unsigned written_from = m->cow_start.offset; unsigned written_to = m->cow_end.offset + m->cow_end.nb_bytes; int first_sc, last_sc; /* Narrow written_from and written_to down to the current cluster */ written_from = MAX(written_from, i << s->cluster_bits); written_to = MIN(written_to, (i + 1) << s->cluster_bits); assert(written_from < written_to); first_sc = offset_to_sc_index(s, written_from); last_sc = offset_to_sc_index(s, written_to - 1); l2_bitmap |= QCOW_OFLAG_SUB_ALLOC_RANGE(first_sc, last_sc + 1); l2_bitmap &= ~QCOW_OFLAG_SUB_ZERO_RANGE(first_sc, last_sc + 1); set_l2_bitmap(s, l2_slice, l2_index + i, l2_bitmap); } } qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); /* * If this was a COW, we need to decrease the refcount of the old cluster. * * Don't discard clusters that reach a refcount of 0 (e.g. compressed * clusters), the next write will reuse them anyway. */ if (!m->keep_old_clusters && j != 0) { for (i = 0; i < j; i++) { qcow2_free_any_cluster(bs, old_cluster[i], QCOW2_DISCARD_NEVER); } } ret = 0; err: g_free(old_cluster); return ret; } /** * Frees the allocated clusters because the request failed and they won't * actually be linked. */ void qcow2_alloc_cluster_abort(BlockDriverState *bs, QCowL2Meta *m) { BDRVQcow2State *s = bs->opaque; if (!has_data_file(bs) && !m->keep_old_clusters) { qcow2_free_clusters(bs, m->alloc_offset, m->nb_clusters << s->cluster_bits, QCOW2_DISCARD_NEVER); } } /* * For a given write request, create a new QCowL2Meta structure, add * it to @m and the BDRVQcow2State.cluster_allocs list. If the write * request does not need copy-on-write or changes to the L2 metadata * then this function does nothing. * * @host_cluster_offset points to the beginning of the first cluster. * * @guest_offset and @bytes indicate the offset and length of the * request. * * @l2_slice contains the L2 entries of all clusters involved in this * write request. * * If @keep_old is true it means that the clusters were already * allocated and will be overwritten. If false then the clusters are * new and we have to decrease the reference count of the old ones. * * Returns 0 on success, -errno on failure. */ static int calculate_l2_meta(BlockDriverState *bs, uint64_t host_cluster_offset, uint64_t guest_offset, unsigned bytes, uint64_t *l2_slice, QCowL2Meta **m, bool keep_old) { BDRVQcow2State *s = bs->opaque; int sc_index, l2_index = offset_to_l2_slice_index(s, guest_offset); uint64_t l2_entry, l2_bitmap; unsigned cow_start_from, cow_end_to; unsigned cow_start_to = offset_into_cluster(s, guest_offset); unsigned cow_end_from = cow_start_to + bytes; unsigned nb_clusters = size_to_clusters(s, cow_end_from); QCowL2Meta *old_m = *m; QCow2SubclusterType type; int i; bool skip_cow = keep_old; assert(nb_clusters <= s->l2_slice_size - l2_index); /* Check the type of all affected subclusters */ for (i = 0; i < nb_clusters; i++) { l2_entry = get_l2_entry(s, l2_slice, l2_index + i); l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i); if (skip_cow) { unsigned write_from = MAX(cow_start_to, i << s->cluster_bits); unsigned write_to = MIN(cow_end_from, (i + 1) << s->cluster_bits); int first_sc = offset_to_sc_index(s, write_from); int last_sc = offset_to_sc_index(s, write_to - 1); int cnt = qcow2_get_subcluster_range_type(bs, l2_entry, l2_bitmap, first_sc, &type); /* Is any of the subclusters of type != QCOW2_SUBCLUSTER_NORMAL ? */ if (type != QCOW2_SUBCLUSTER_NORMAL || first_sc + cnt <= last_sc) { skip_cow = false; } } else { /* If we can't skip the cow we can still look for invalid entries */ type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, 0); } if (type == QCOW2_SUBCLUSTER_INVALID) { int l1_index = offset_to_l1_index(s, guest_offset); uint64_t l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; qcow2_signal_corruption(bs, true, -1, -1, "Invalid cluster " "entry found (L2 offset: %#" PRIx64 ", L2 index: %#x)", l2_offset, l2_index + i); return -EIO; } } if (skip_cow) { return 0; } /* Get the L2 entry of the first cluster */ l2_entry = get_l2_entry(s, l2_slice, l2_index); l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index); sc_index = offset_to_sc_index(s, guest_offset); type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index); if (!keep_old) { switch (type) { case QCOW2_SUBCLUSTER_COMPRESSED: cow_start_from = 0; break; case QCOW2_SUBCLUSTER_NORMAL: case QCOW2_SUBCLUSTER_ZERO_ALLOC: case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: if (has_subclusters(s)) { /* Skip all leading zero and unallocated subclusters */ uint32_t alloc_bitmap = l2_bitmap & QCOW_L2_BITMAP_ALL_ALLOC; cow_start_from = MIN(sc_index, ctz32(alloc_bitmap)) << s->subcluster_bits; } else { cow_start_from = 0; } break; case QCOW2_SUBCLUSTER_ZERO_PLAIN: case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN: cow_start_from = sc_index << s->subcluster_bits; break; default: g_assert_not_reached(); } } else { switch (type) { case QCOW2_SUBCLUSTER_NORMAL: cow_start_from = cow_start_to; break; case QCOW2_SUBCLUSTER_ZERO_ALLOC: case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: cow_start_from = sc_index << s->subcluster_bits; break; default: g_assert_not_reached(); } } /* Get the L2 entry of the last cluster */ l2_index += nb_clusters - 1; l2_entry = get_l2_entry(s, l2_slice, l2_index); l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index); sc_index = offset_to_sc_index(s, guest_offset + bytes - 1); type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index); if (!keep_old) { switch (type) { case QCOW2_SUBCLUSTER_COMPRESSED: cow_end_to = ROUND_UP(cow_end_from, s->cluster_size); break; case QCOW2_SUBCLUSTER_NORMAL: case QCOW2_SUBCLUSTER_ZERO_ALLOC: case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: cow_end_to = ROUND_UP(cow_end_from, s->cluster_size); if (has_subclusters(s)) { /* Skip all trailing zero and unallocated subclusters */ uint32_t alloc_bitmap = l2_bitmap & QCOW_L2_BITMAP_ALL_ALLOC; cow_end_to -= MIN(s->subclusters_per_cluster - sc_index - 1, clz32(alloc_bitmap)) << s->subcluster_bits; } break; case QCOW2_SUBCLUSTER_ZERO_PLAIN: case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN: cow_end_to = ROUND_UP(cow_end_from, s->subcluster_size); break; default: g_assert_not_reached(); } } else { switch (type) { case QCOW2_SUBCLUSTER_NORMAL: cow_end_to = cow_end_from; break; case QCOW2_SUBCLUSTER_ZERO_ALLOC: case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: cow_end_to = ROUND_UP(cow_end_from, s->subcluster_size); break; default: g_assert_not_reached(); } } *m = g_malloc0(sizeof(**m)); **m = (QCowL2Meta) { .next = old_m, .alloc_offset = host_cluster_offset, .offset = start_of_cluster(s, guest_offset), .nb_clusters = nb_clusters, .keep_old_clusters = keep_old, .cow_start = { .offset = cow_start_from, .nb_bytes = cow_start_to - cow_start_from, }, .cow_end = { .offset = cow_end_from, .nb_bytes = cow_end_to - cow_end_from, }, }; qemu_co_queue_init(&(*m)->dependent_requests); QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight); return 0; } /* * Returns true if writing to the cluster pointed to by @l2_entry * requires a new allocation (that is, if the cluster is unallocated * or has refcount > 1 and therefore cannot be written in-place). */ static bool cluster_needs_new_alloc(BlockDriverState *bs, uint64_t l2_entry) { switch (qcow2_get_cluster_type(bs, l2_entry)) { case QCOW2_CLUSTER_NORMAL: case QCOW2_CLUSTER_ZERO_ALLOC: if (l2_entry & QCOW_OFLAG_COPIED) { return false; } /* fallthrough */ case QCOW2_CLUSTER_UNALLOCATED: case QCOW2_CLUSTER_COMPRESSED: case QCOW2_CLUSTER_ZERO_PLAIN: return true; default: abort(); } } /* * Returns the number of contiguous clusters that can be written to * using one single write request, starting from @l2_index. * At most @nb_clusters are checked. * * If @new_alloc is true this counts clusters that are either * unallocated, or allocated but with refcount > 1 (so they need to be * newly allocated and COWed). * * If @new_alloc is false this counts clusters that are already * allocated and can be overwritten in-place (this includes clusters * of type QCOW2_CLUSTER_ZERO_ALLOC). */ static int count_single_write_clusters(BlockDriverState *bs, int nb_clusters, uint64_t *l2_slice, int l2_index, bool new_alloc) { BDRVQcow2State *s = bs->opaque; uint64_t l2_entry = get_l2_entry(s, l2_slice, l2_index); uint64_t expected_offset = l2_entry & L2E_OFFSET_MASK; int i; for (i = 0; i < nb_clusters; i++) { l2_entry = get_l2_entry(s, l2_slice, l2_index + i); if (cluster_needs_new_alloc(bs, l2_entry) != new_alloc) { break; } if (!new_alloc) { if (expected_offset != (l2_entry & L2E_OFFSET_MASK)) { break; } expected_offset += s->cluster_size; } } 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) { BDRVQcow2State *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 = start_of_cluster(s, l2meta_cow_start(old_alloc)); uint64_t old_end = ROUND_UP(l2meta_cow_end(old_alloc), s->cluster_size); 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_queue_wait(&old_alloc->dependent_requests, &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 new * allocation there are at the given guest_offset (up to *bytes). * If *host_offset is not INV_OFFSET, 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 can be overwritten in-place but doesn't have * the right physical offset. * * 1: if allocated clusters that can be overwritten in place 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) { BDRVQcow2State *s = bs->opaque; int l2_index; uint64_t l2_entry, cluster_offset; uint64_t *l2_slice; uint64_t nb_clusters; unsigned int keep_clusters; int ret; trace_qcow2_handle_copied(qemu_coroutine_self(), guest_offset, *host_offset, *bytes); assert(*host_offset == INV_OFFSET || offset_into_cluster(s, guest_offset) == offset_into_cluster(s, *host_offset)); /* * Calculate the number of clusters to look for. We stop at L2 slice * boundaries to keep things simple. */ nb_clusters = size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes); l2_index = offset_to_l2_slice_index(s, guest_offset); nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index); /* Limit total byte count to BDRV_REQUEST_MAX_BYTES */ nb_clusters = MIN(nb_clusters, BDRV_REQUEST_MAX_BYTES >> s->cluster_bits); /* Find L2 entry for the first involved cluster */ ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index); if (ret < 0) { return ret; } l2_entry = get_l2_entry(s, l2_slice, l2_index); cluster_offset = l2_entry & L2E_OFFSET_MASK; if (!cluster_needs_new_alloc(bs, l2_entry)) { if (offset_into_cluster(s, cluster_offset)) { qcow2_signal_corruption(bs, true, -1, -1, "%s cluster offset " "%#" PRIx64 " unaligned (guest offset: %#" PRIx64 ")", l2_entry & QCOW_OFLAG_ZERO ? "Preallocated zero" : "Data", cluster_offset, guest_offset); ret = -EIO; goto out; } /* If a specific host_offset is required, check it */ if (*host_offset != INV_OFFSET && cluster_offset != *host_offset) { *bytes = 0; ret = 0; goto out; } /* We keep all QCOW_OFLAG_COPIED clusters */ keep_clusters = count_single_write_clusters(bs, nb_clusters, l2_slice, l2_index, false); assert(keep_clusters <= nb_clusters); *bytes = MIN(*bytes, keep_clusters * s->cluster_size - offset_into_cluster(s, guest_offset)); assert(*bytes != 0); ret = calculate_l2_meta(bs, cluster_offset, guest_offset, *bytes, l2_slice, m, true); if (ret < 0) { goto out; } ret = 1; } else { ret = 0; } /* Cleanup */ out: qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); /* 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 + 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 not INV_OFFSET, 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 INV_OFFSET, 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, uint64_t *nb_clusters) { BDRVQcow2State *s = bs->opaque; trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset, *host_offset, *nb_clusters); if (has_data_file(bs)) { assert(*host_offset == INV_OFFSET || *host_offset == start_of_cluster(s, guest_offset)); *host_offset = start_of_cluster(s, guest_offset); return 0; } /* Allocate new clusters */ trace_qcow2_cluster_alloc_phys(qemu_coroutine_self()); if (*host_offset == INV_OFFSET) { 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 { int64_t 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 is either still unallocated or * cannot be overwritten in-place. If *host_offset is not INV_OFFSET, * 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) { BDRVQcow2State *s = bs->opaque; int l2_index; uint64_t *l2_slice; uint64_t 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 slice * boundaries to keep things simple. */ nb_clusters = size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes); l2_index = offset_to_l2_slice_index(s, guest_offset); nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index); /* Limit total allocation byte count to BDRV_REQUEST_MAX_BYTES */ nb_clusters = MIN(nb_clusters, BDRV_REQUEST_MAX_BYTES >> s->cluster_bits); /* Find L2 entry for the first involved cluster */ ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index); if (ret < 0) { return ret; } nb_clusters = count_single_write_clusters(bs, nb_clusters, l2_slice, l2_index, true); /* 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); /* Allocate at a given offset in the image file */ alloc_cluster_offset = *host_offset == INV_OFFSET ? INV_OFFSET : start_of_cluster(s, *host_offset); ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset, &nb_clusters); if (ret < 0) { goto out; } /* Can't extend contiguous allocation */ if (nb_clusters == 0) { *bytes = 0; ret = 0; goto out; } assert(alloc_cluster_offset != INV_OFFSET); /* * Save info needed for meta data update. * * requested_bytes: Number of bytes from the start of the first * newly allocated cluster to the end of the (possibly shortened * before) write request. * * avail_bytes: Number of bytes from the start of the first * newly allocated to the end of the last newly allocated cluster. * * nb_bytes: The number of bytes 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) */ uint64_t requested_bytes = *bytes + offset_into_cluster(s, guest_offset); int avail_bytes = nb_clusters << s->cluster_bits; int nb_bytes = MIN(requested_bytes, avail_bytes); *host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset); *bytes = MIN(*bytes, nb_bytes - offset_into_cluster(s, guest_offset)); assert(*bytes != 0); ret = calculate_l2_meta(bs, alloc_cluster_offset, guest_offset, *bytes, l2_slice, m, false); if (ret < 0) { goto out; } ret = 1; out: qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); return ret; } /* * For a given area on the virtual disk defined by @offset and @bytes, * find the corresponding area on the qcow2 image, allocating new * clusters (or subclusters) if necessary. The result can span a * combination of allocated and previously unallocated clusters. * * Note that offset may not be cluster aligned. In this case, the returned * *host_offset points to exact byte referenced by offset and therefore * isn't cluster aligned as well. * * On return, @host_offset is set to the beginning of the requested * area. This area is guaranteed to be contiguous on the qcow2 file * but it can be smaller than initially requested. In this case @bytes * is updated with the actual size. * * If any clusters or subclusters were allocated then @m contains a * list with the information of all the affected regions. Note that * this can happen regardless of whether this function succeeds or * not. The caller is responsible for updating the L2 metadata of the * allocated clusters (on success) or freeing them (on failure), and * for clearing the contents of @m afterwards in both cases. * * 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_host_offset(BlockDriverState *bs, uint64_t offset, unsigned int *bytes, uint64_t *host_offset, QCowL2Meta **m) { BDRVQcow2State *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, *bytes); again: start = offset; remaining = *bytes; cluster_offset = INV_OFFSET; *host_offset = INV_OFFSET; cur_bytes = 0; *m = NULL; while (true) { if (*host_offset == INV_OFFSET && cluster_offset != INV_OFFSET) { *host_offset = cluster_offset; } assert(remaining >= cur_bytes); start += cur_bytes; remaining -= cur_bytes; if (cluster_offset != INV_OFFSET) { 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; } } *bytes -= remaining; assert(*bytes > 0); assert(*host_offset != INV_OFFSET); assert(offset_into_cluster(s, *host_offset) == offset_into_cluster(s, offset)); return 0; } /* * This discards as many clusters of nb_clusters as possible at once (i.e. * all clusters in the same L2 slice) and returns the number of discarded * clusters. */ static int discard_in_l2_slice(BlockDriverState *bs, uint64_t offset, uint64_t nb_clusters, enum qcow2_discard_type type, bool full_discard) { BDRVQcow2State *s = bs->opaque; uint64_t *l2_slice; int l2_index; int ret; int i; ret = get_cluster_table(bs, offset, &l2_slice, &l2_index); if (ret < 0) { return ret; } /* Limit nb_clusters to one L2 slice */ nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index); assert(nb_clusters <= INT_MAX); for (i = 0; i < nb_clusters; i++) { uint64_t old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i); uint64_t old_l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i); uint64_t new_l2_entry = old_l2_entry; uint64_t new_l2_bitmap = old_l2_bitmap; QCow2ClusterType cluster_type = qcow2_get_cluster_type(bs, old_l2_entry); /* * If full_discard is true, the cluster should not read back as zeroes, * but rather fall through to the backing file. * * 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_block_status(bs) here, but we're * holding s->lock, so that doesn't work today. */ if (full_discard) { new_l2_entry = new_l2_bitmap = 0; } else if (bs->backing || qcow2_cluster_is_allocated(cluster_type)) { if (has_subclusters(s)) { new_l2_entry = 0; new_l2_bitmap = QCOW_L2_BITMAP_ALL_ZEROES; } else { new_l2_entry = s->qcow_version >= 3 ? QCOW_OFLAG_ZERO : 0; } } if (old_l2_entry == new_l2_entry && old_l2_bitmap == new_l2_bitmap) { continue; } /* First remove L2 entries */ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); set_l2_entry(s, l2_slice, l2_index + i, new_l2_entry); if (has_subclusters(s)) { set_l2_bitmap(s, l2_slice, l2_index + i, new_l2_bitmap); } /* Then decrease the refcount */ qcow2_free_any_cluster(bs, old_l2_entry, type); } qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); return nb_clusters; } int qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset, uint64_t bytes, enum qcow2_discard_type type, bool full_discard) { BDRVQcow2State *s = bs->opaque; uint64_t end_offset = offset + bytes; uint64_t nb_clusters; int64_t cleared; int ret; /* Caller must pass aligned values, except at image end */ assert(QEMU_IS_ALIGNED(offset, s->cluster_size)); assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size) || end_offset == bs->total_sectors << BDRV_SECTOR_BITS); nb_clusters = size_to_clusters(s, bytes); s->cache_discards = true; /* Each L2 slice is handled by its own loop iteration */ while (nb_clusters > 0) { cleared = discard_in_l2_slice(bs, offset, nb_clusters, type, full_discard); if (cleared < 0) { ret = cleared; goto fail; } nb_clusters -= cleared; offset += (cleared * 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 slice) and returns the number of zeroed * clusters. */ static int zero_in_l2_slice(BlockDriverState *bs, uint64_t offset, uint64_t nb_clusters, int flags) { BDRVQcow2State *s = bs->opaque; uint64_t *l2_slice; int l2_index; int ret; int i; ret = get_cluster_table(bs, offset, &l2_slice, &l2_index); if (ret < 0) { return ret; } /* Limit nb_clusters to one L2 slice */ nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index); assert(nb_clusters <= INT_MAX); for (i = 0; i < nb_clusters; i++) { uint64_t old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i); uint64_t old_l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i); QCow2ClusterType type = qcow2_get_cluster_type(bs, old_l2_entry); bool unmap = (type == QCOW2_CLUSTER_COMPRESSED) || ((flags & BDRV_REQ_MAY_UNMAP) && qcow2_cluster_is_allocated(type)); uint64_t new_l2_entry = unmap ? 0 : old_l2_entry; uint64_t new_l2_bitmap = old_l2_bitmap; if (has_subclusters(s)) { new_l2_bitmap = QCOW_L2_BITMAP_ALL_ZEROES; } else { new_l2_entry |= QCOW_OFLAG_ZERO; } if (old_l2_entry == new_l2_entry && old_l2_bitmap == new_l2_bitmap) { continue; } /* First update L2 entries */ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); set_l2_entry(s, l2_slice, l2_index + i, new_l2_entry); if (has_subclusters(s)) { set_l2_bitmap(s, l2_slice, l2_index + i, new_l2_bitmap); } /* Then decrease the refcount */ if (unmap) { qcow2_free_any_cluster(bs, old_l2_entry, QCOW2_DISCARD_REQUEST); } } qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); return nb_clusters; } static int zero_l2_subclusters(BlockDriverState *bs, uint64_t offset, unsigned nb_subclusters) { BDRVQcow2State *s = bs->opaque; uint64_t *l2_slice; uint64_t old_l2_bitmap, l2_bitmap; int l2_index, ret, sc = offset_to_sc_index(s, offset); /* For full clusters use zero_in_l2_slice() instead */ assert(nb_subclusters > 0 && nb_subclusters < s->subclusters_per_cluster); assert(sc + nb_subclusters <= s->subclusters_per_cluster); assert(offset_into_subcluster(s, offset) == 0); ret = get_cluster_table(bs, offset, &l2_slice, &l2_index); if (ret < 0) { return ret; } switch (qcow2_get_cluster_type(bs, get_l2_entry(s, l2_slice, l2_index))) { case QCOW2_CLUSTER_COMPRESSED: ret = -ENOTSUP; /* We cannot partially zeroize compressed clusters */ goto out; case QCOW2_CLUSTER_NORMAL: case QCOW2_CLUSTER_UNALLOCATED: break; default: g_assert_not_reached(); } old_l2_bitmap = l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index); l2_bitmap |= QCOW_OFLAG_SUB_ZERO_RANGE(sc, sc + nb_subclusters); l2_bitmap &= ~QCOW_OFLAG_SUB_ALLOC_RANGE(sc, sc + nb_subclusters); if (old_l2_bitmap != l2_bitmap) { set_l2_bitmap(s, l2_slice, l2_index, l2_bitmap); qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); } ret = 0; out: qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); return ret; } int qcow2_subcluster_zeroize(BlockDriverState *bs, uint64_t offset, uint64_t bytes, int flags) { BDRVQcow2State *s = bs->opaque; uint64_t end_offset = offset + bytes; uint64_t nb_clusters; unsigned head, tail; int64_t cleared; int ret; /* If we have to stay in sync with an external data file, zero out * s->data_file first. */ if (data_file_is_raw(bs)) { assert(has_data_file(bs)); ret = bdrv_co_pwrite_zeroes(s->data_file, offset, bytes, flags); if (ret < 0) { return ret; } } /* Caller must pass aligned values, except at image end */ assert(offset_into_subcluster(s, offset) == 0); assert(offset_into_subcluster(s, end_offset) == 0 || end_offset >= bs->total_sectors << BDRV_SECTOR_BITS); /* * The zero flag is only supported by version 3 and newer. However, if we * have no backing file, we can resort to discard in version 2. */ if (s->qcow_version < 3) { if (!bs->backing) { return qcow2_cluster_discard(bs, offset, bytes, QCOW2_DISCARD_REQUEST, false); } return -ENOTSUP; } head = MIN(end_offset, ROUND_UP(offset, s->cluster_size)) - offset; offset += head; tail = (end_offset >= bs->total_sectors << BDRV_SECTOR_BITS) ? 0 : end_offset - MAX(offset, start_of_cluster(s, end_offset)); end_offset -= tail; s->cache_discards = true; if (head) { ret = zero_l2_subclusters(bs, offset - head, size_to_subclusters(s, head)); if (ret < 0) { goto fail; } } /* Each L2 slice is handled by its own loop iteration */ nb_clusters = size_to_clusters(s, end_offset - offset); while (nb_clusters > 0) { cleared = zero_in_l2_slice(bs, offset, nb_clusters, flags); if (cleared < 0) { ret = cleared; goto fail; } nb_clusters -= cleared; offset += (cleared * s->cluster_size); } if (tail) { ret = zero_l2_subclusters(bs, end_offset, size_to_subclusters(s, tail)); if (ret < 0) { goto fail; } } 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, void *cb_opaque) { BDRVQcow2State *s = bs->opaque; bool is_active_l1 = (l1_table == s->l1_table); uint64_t *l2_slice = NULL; unsigned slice, slice_size2, n_slices; int ret; int i, j; /* qcow2_downgrade() is not allowed in images with subclusters */ assert(!has_subclusters(s)); slice_size2 = s->l2_slice_size * l2_entry_size(s); n_slices = s->cluster_size / slice_size2; if (!is_active_l1) { /* inactive L2 tables require a buffer to be stored in when loading * them from disk */ l2_slice = qemu_try_blockalign(bs->file->bs, slice_size2); if (l2_slice == NULL) { return -ENOMEM; } } for (i = 0; i < l1_size; i++) { uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK; uint64_t l2_refcount; if (!l2_offset) { /* unallocated */ (*visited_l1_entries)++; if (status_cb) { status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque); } 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; } ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits, &l2_refcount); if (ret < 0) { goto fail; } for (slice = 0; slice < n_slices; slice++) { uint64_t slice_offset = l2_offset + slice * slice_size2; bool l2_dirty = false; if (is_active_l1) { /* get active L2 tables from cache */ ret = qcow2_cache_get(bs, s->l2_table_cache, slice_offset, (void **)&l2_slice); } else { /* load inactive L2 tables from disk */ ret = bdrv_pread(bs->file, slice_offset, l2_slice, slice_size2); } if (ret < 0) { goto fail; } for (j = 0; j < s->l2_slice_size; j++) { uint64_t l2_entry = get_l2_entry(s, l2_slice, j); int64_t offset = l2_entry & L2E_OFFSET_MASK; QCow2ClusterType cluster_type = qcow2_get_cluster_type(bs, l2_entry); if (cluster_type != QCOW2_CLUSTER_ZERO_PLAIN && cluster_type != QCOW2_CLUSTER_ZERO_ALLOC) { continue; } if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) { if (!bs->backing) { /* * not backed; therefore we can simply deallocate the * cluster. No need to call set_l2_bitmap(), this * function doesn't support images with subclusters. */ set_l2_entry(s, l2_slice, j, 0); l2_dirty = true; continue; } offset = qcow2_alloc_clusters(bs, s->cluster_size); if (offset < 0) { ret = offset; goto fail; } /* The offset must fit in the offset field */ assert((offset & L2E_OFFSET_MASK) == offset); 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)) { int l2_index = slice * s->l2_slice_size + j; qcow2_signal_corruption( bs, true, -1, -1, "Cluster allocation offset " "%#" PRIx64 " unaligned (L2 offset: %#" PRIx64 ", L2 index: %#x)", offset, l2_offset, l2_index); if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) { 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, true); if (ret < 0) { if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) { qcow2_free_clusters(bs, offset, s->cluster_size, QCOW2_DISCARD_ALWAYS); } goto fail; } ret = bdrv_pwrite_zeroes(s->data_file, offset, s->cluster_size, 0); if (ret < 0) { if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) { qcow2_free_clusters(bs, offset, s->cluster_size, QCOW2_DISCARD_ALWAYS); } goto fail; } if (l2_refcount == 1) { set_l2_entry(s, l2_slice, j, offset | QCOW_OFLAG_COPIED); } else { set_l2_entry(s, l2_slice, j, offset); } /* * No need to call set_l2_bitmap() after set_l2_entry() because * this function doesn't support images with subclusters. */ l2_dirty = true; } if (is_active_l1) { if (l2_dirty) { qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); qcow2_cache_depends_on_flush(s->l2_table_cache); } qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); } else { if (l2_dirty) { ret = qcow2_pre_write_overlap_check( bs, QCOW2_OL_INACTIVE_L2 | QCOW2_OL_ACTIVE_L2, slice_offset, slice_size2, false); if (ret < 0) { goto fail; } ret = bdrv_pwrite(bs->file, slice_offset, l2_slice, slice_size2); if (ret < 0) { goto fail; } } } } (*visited_l1_entries)++; if (status_cb) { status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque); } } ret = 0; fail: if (l2_slice) { if (!is_active_l1) { qemu_vfree(l2_slice); } else { qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice); } } 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, void *cb_opaque) { BDRVQcow2State *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, cb_opaque); 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_size2; uint64_t *new_l1_table; Error *local_err = NULL; ret = qcow2_validate_table(bs, s->snapshots[i].l1_table_offset, s->snapshots[i].l1_size, L1E_SIZE, QCOW_MAX_L1_SIZE, "Snapshot L1 table", &local_err); if (ret < 0) { error_report_err(local_err); goto fail; } l1_size2 = s->snapshots[i].l1_size * L1E_SIZE; new_l1_table = g_try_realloc(l1_table, l1_size2); if (!new_l1_table) { ret = -ENOMEM; goto fail; } l1_table = new_l1_table; ret = bdrv_pread(bs->file, s->snapshots[i].l1_table_offset, l1_table, l1_size2); 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, cb_opaque); if (ret < 0) { goto fail; } } ret = 0; fail: g_free(l1_table); return ret; }