| /* |
| * 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]; |
| int l1_start_index; |
| int i, ret; |
| |
| l1_start_index = l1_index & ~(L1_ENTRIES_PER_SECTOR - 1); |
| for (i = 0; i < L1_ENTRIES_PER_SECTOR; i++) { |
| buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]); |
| } |
| |
| 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); |
| |
| ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &old_table); |
| if (ret < 0) { |
| goto fail; |
| } |
| } |
| |
| /* 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(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 */ |
| void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num, |
| uint8_t *out_buf, const uint8_t *in_buf, |
| int nb_sectors, int enc, |
| const AES_KEY *key) |
| { |
| union { |
| uint64_t ll[2]; |
| uint8_t b[16]; |
| } ivec; |
| int i; |
| |
| for(i = 0; i < nb_sectors; i++) { |
| ivec.ll[0] = cpu_to_le64(sector_num); |
| ivec.ll[1] = 0; |
| AES_cbc_encrypt(in_buf, out_buf, 512, key, |
| ivec.b, enc); |
| sector_num++; |
| in_buf += 512; |
| out_buf += 512; |
| } |
| } |
| |
| static int 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 (s->crypt_method) { |
| qcow2_encrypt_sectors(s, start_sect + n_start, |
| iov.iov_base, iov.iov_base, n, 1, |
| &s->aes_encrypt_key); |
| } |
| |
| 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; |
| } |
| |
| /* 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_cache_put(bs, s->l2_table_cache, (void**) &l2_table); |
| return -EIO; |
| } |
| 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; |
| 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; |
| } |
| |
| /* |
| * 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; |
| |
| /* 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(s->l2_table_cache, l2_table); |
| l2_table[l2_index] = cpu_to_be64(cluster_offset); |
| ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); |
| if (ret < 0) { |
| return 0; |
| } |
| |
| 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(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); |
| } |
| |
| |
| ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); |
| if (ret < 0) { |
| goto err; |
| } |
| |
| /* |
| * 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, pret; |
| |
| 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 (*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: |
| pret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); |
| if (pret < 0) { |
| return pret; |
| } |
| |
| /* 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) { |
| *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); |
| |
| ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| /* 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 = *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) |
| { |
| 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]); |
| |
| /* |
| * 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. |
| */ |
| switch (qcow2_get_cluster_type(old_l2_entry)) { |
| case QCOW2_CLUSTER_UNALLOCATED: |
| if (!bs->backing_hd) { |
| continue; |
| } |
| break; |
| |
| case QCOW2_CLUSTER_ZERO: |
| continue; |
| |
| case QCOW2_CLUSTER_NORMAL: |
| case QCOW2_CLUSTER_COMPRESSED: |
| break; |
| |
| default: |
| abort(); |
| } |
| |
| /* First remove L2 entries */ |
| qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); |
| if (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); |
| } |
| |
| ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| return nb_clusters; |
| } |
| |
| int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset, |
| int nb_sectors, enum qcow2_discard_type type) |
| { |
| 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); |
| 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(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); |
| } |
| } |
| |
| ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); |
| if (ret < 0) { |
| return ret; |
| } |
| |
| 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). |
| * |
| * expanded_clusters is a bitmap where every bit corresponds to one cluster in |
| * the image file; a bit gets set if the corresponding cluster has been used for |
| * zero expansion (i.e., has been filled with zeroes and is referenced from an |
| * L2 table). nb_clusters contains the total cluster count of the image file, |
| * i.e., the number of bits in expanded_clusters. |
| */ |
| static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table, |
| int l1_size, uint8_t **expanded_clusters, |
| uint64_t *nb_clusters) |
| { |
| 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; |
| |
| if (!l2_offset) { |
| /* unallocated */ |
| continue; |
| } |
| |
| 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; |
| } |
| |
| 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, cluster_index; |
| int cluster_type = qcow2_get_cluster_type(l2_entry); |
| bool preallocated = offset != 0; |
| |
| if (cluster_type == QCOW2_CLUSTER_NORMAL) { |
| cluster_index = offset >> s->cluster_bits; |
| assert((cluster_index >= 0) && (cluster_index < *nb_clusters)); |
| if ((*expanded_clusters)[cluster_index / 8] & |
| (1 << (cluster_index % 8))) { |
| /* Probably a shared L2 table; this cluster was a zero |
| * cluster which has been expanded, its refcount |
| * therefore most likely requires an update. */ |
| ret = qcow2_update_cluster_refcount(bs, cluster_index, 1, |
| QCOW2_DISCARD_NEVER); |
| if (ret < 0) { |
| goto fail; |
| } |
| /* Since we just increased the refcount, the COPIED flag may |
| * no longer be set. */ |
| l2_table[j] = cpu_to_be64(l2_entry & ~QCOW_OFLAG_COPIED); |
| l2_dirty = true; |
| } |
| continue; |
| } |
| else if (qcow2_get_cluster_type(l2_entry) != 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; |
| } |
| } |
| |
| 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; |
| } |
| |
| l2_table[j] = cpu_to_be64(offset | QCOW_OFLAG_COPIED); |
| l2_dirty = true; |
| |
| cluster_index = offset >> s->cluster_bits; |
| |
| if (cluster_index >= *nb_clusters) { |
| uint64_t old_bitmap_size = (*nb_clusters + 7) / 8; |
| uint64_t new_bitmap_size; |
| /* The offset may lie beyond the old end of the underlying image |
| * file for growable files only */ |
| assert(bs->file->growable); |
| *nb_clusters = size_to_clusters(s, bs->file->total_sectors * |
| BDRV_SECTOR_SIZE); |
| new_bitmap_size = (*nb_clusters + 7) / 8; |
| *expanded_clusters = g_realloc(*expanded_clusters, |
| new_bitmap_size); |
| /* clear the newly allocated space */ |
| memset(&(*expanded_clusters)[old_bitmap_size], 0, |
| new_bitmap_size - old_bitmap_size); |
| } |
| |
| assert((cluster_index >= 0) && (cluster_index < *nb_clusters)); |
| (*expanded_clusters)[cluster_index / 8] |= 1 << (cluster_index % 8); |
| } |
| |
| if (is_active_l1) { |
| if (l2_dirty) { |
| qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); |
| qcow2_cache_depends_on_flush(s->l2_table_cache); |
| } |
| ret = qcow2_cache_put(bs, s->l2_table_cache, (void **)&l2_table); |
| if (ret < 0) { |
| l2_table = NULL; |
| goto fail; |
| } |
| } 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; |
| } |
| } |
| } |
| } |
| |
| ret = 0; |
| |
| fail: |
| if (l2_table) { |
| if (!is_active_l1) { |
| qemu_vfree(l2_table); |
| } else { |
| if (ret < 0) { |
| qcow2_cache_put(bs, s->l2_table_cache, (void **)&l2_table); |
| } else { |
| ret = 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) |
| { |
| BDRVQcowState *s = bs->opaque; |
| uint64_t *l1_table = NULL; |
| uint64_t nb_clusters; |
| uint8_t *expanded_clusters; |
| int ret; |
| int i, j; |
| |
| nb_clusters = size_to_clusters(s, bs->file->total_sectors * |
| BDRV_SECTOR_SIZE); |
| expanded_clusters = g_try_malloc0((nb_clusters + 7) / 8); |
| if (expanded_clusters == NULL) { |
| ret = -ENOMEM; |
| goto fail; |
| } |
| |
| ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size, |
| &expanded_clusters, &nb_clusters); |
| 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, |
| &expanded_clusters, &nb_clusters); |
| if (ret < 0) { |
| goto fail; |
| } |
| } |
| |
| ret = 0; |
| |
| fail: |
| g_free(expanded_clusters); |
| g_free(l1_table); |
| return ret; |
| } |