root / block / qcow2-refcount.c @ 09508d13
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/*
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* Block driver for the QCOW version 2 format
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*
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* Copyright (c) 2004-2006 Fabrice Bellard
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu-common.h" |
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#include "block_int.h" |
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#include "block/qcow2.h" |
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|
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static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size);
|
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static int update_refcount(BlockDriverState *bs, |
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int64_t offset, int64_t length, |
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int addend);
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|
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static int cache_refcount_updates = 0; |
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static int write_refcount_block(BDRVQcowState *s) |
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{ |
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size_t size = s->cluster_size; |
40 |
|
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if (s->refcount_block_cache_offset == 0) { |
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return 0; |
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} |
44 |
|
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if (bdrv_pwrite(s->hd, s->refcount_block_cache_offset,
|
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s->refcount_block_cache, size) != size) |
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{ |
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return -EIO;
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} |
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return 0; |
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} |
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|
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/*********************************************************/
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/* refcount handling */
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|
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int qcow2_refcount_init(BlockDriverState *bs)
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{ |
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BDRVQcowState *s = bs->opaque; |
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int ret, refcount_table_size2, i;
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|
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s->refcount_block_cache = qemu_malloc(s->cluster_size); |
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refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t);
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s->refcount_table = qemu_malloc(refcount_table_size2); |
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if (s->refcount_table_size > 0) { |
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ret = bdrv_pread(s->hd, s->refcount_table_offset, |
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s->refcount_table, refcount_table_size2); |
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if (ret != refcount_table_size2)
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goto fail;
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for(i = 0; i < s->refcount_table_size; i++) |
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be64_to_cpus(&s->refcount_table[i]); |
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} |
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return 0; |
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fail:
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return -ENOMEM;
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} |
77 |
|
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void qcow2_refcount_close(BlockDriverState *bs)
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{ |
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BDRVQcowState *s = bs->opaque; |
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qemu_free(s->refcount_block_cache); |
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qemu_free(s->refcount_table); |
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} |
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|
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|
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static int load_refcount_block(BlockDriverState *bs, |
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int64_t refcount_block_offset) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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int ret;
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|
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if (cache_refcount_updates) {
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write_refcount_block(s); |
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} |
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ret = bdrv_pread(s->hd, refcount_block_offset, s->refcount_block_cache, |
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s->cluster_size); |
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if (ret != s->cluster_size)
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return -EIO;
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s->refcount_block_cache_offset = refcount_block_offset; |
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return 0; |
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} |
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|
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static int get_refcount(BlockDriverState *bs, int64_t cluster_index) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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int refcount_table_index, block_index;
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int64_t refcount_block_offset; |
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|
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refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); |
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if (refcount_table_index >= s->refcount_table_size)
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return 0; |
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refcount_block_offset = s->refcount_table[refcount_table_index]; |
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if (!refcount_block_offset)
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return 0; |
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if (refcount_block_offset != s->refcount_block_cache_offset) {
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/* better than nothing: return allocated if read error */
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if (load_refcount_block(bs, refcount_block_offset) < 0) |
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return 1; |
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} |
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block_index = cluster_index & |
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((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); |
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return be16_to_cpu(s->refcount_block_cache[block_index]);
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} |
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|
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static int grow_refcount_table(BlockDriverState *bs, int min_size) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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int new_table_size, new_table_size2, refcount_table_clusters, i, ret;
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uint64_t *new_table; |
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int64_t table_offset; |
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uint8_t data[12];
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int old_table_size;
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int64_t old_table_offset; |
135 |
|
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if (min_size <= s->refcount_table_size)
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return 0; |
138 |
/* compute new table size */
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refcount_table_clusters = s->refcount_table_size >> (s->cluster_bits - 3);
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for(;;) {
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if (refcount_table_clusters == 0) { |
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refcount_table_clusters = 1;
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} else {
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refcount_table_clusters = (refcount_table_clusters * 3 + 1) / 2; |
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} |
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new_table_size = refcount_table_clusters << (s->cluster_bits - 3);
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if (min_size <= new_table_size)
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break;
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} |
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#ifdef DEBUG_ALLOC2
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printf("grow_refcount_table from %d to %d\n",
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s->refcount_table_size, |
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new_table_size); |
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#endif
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new_table_size2 = new_table_size * sizeof(uint64_t);
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new_table = qemu_mallocz(new_table_size2); |
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memcpy(new_table, s->refcount_table, |
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s->refcount_table_size * sizeof(uint64_t));
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for(i = 0; i < s->refcount_table_size; i++) |
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cpu_to_be64s(&new_table[i]); |
161 |
/* Note: we cannot update the refcount now to avoid recursion */
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table_offset = alloc_clusters_noref(bs, new_table_size2); |
163 |
ret = bdrv_pwrite(s->hd, table_offset, new_table, new_table_size2); |
164 |
if (ret != new_table_size2)
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goto fail;
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for(i = 0; i < s->refcount_table_size; i++) |
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be64_to_cpus(&new_table[i]); |
168 |
|
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cpu_to_be64w((uint64_t*)data, table_offset); |
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cpu_to_be32w((uint32_t*)(data + 8), refcount_table_clusters);
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ret = bdrv_pwrite(s->hd, offsetof(QCowHeader, refcount_table_offset), |
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data, sizeof(data));
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if (ret != sizeof(data)) { |
174 |
goto fail;
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} |
176 |
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qemu_free(s->refcount_table); |
178 |
old_table_offset = s->refcount_table_offset; |
179 |
old_table_size = s->refcount_table_size; |
180 |
s->refcount_table = new_table; |
181 |
s->refcount_table_size = new_table_size; |
182 |
s->refcount_table_offset = table_offset; |
183 |
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update_refcount(bs, table_offset, new_table_size2, 1);
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qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t));
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return 0; |
187 |
fail:
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qemu_free(new_table); |
189 |
return ret < 0 ? ret : -EIO; |
190 |
} |
191 |
|
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static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index)
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{ |
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BDRVQcowState *s = bs->opaque; |
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int64_t offset, refcount_block_offset; |
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unsigned int refcount_table_index; |
198 |
int ret;
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uint64_t data64; |
200 |
int cache = cache_refcount_updates;
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|
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/* Find L1 index and grow refcount table if needed */
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refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); |
204 |
if (refcount_table_index >= s->refcount_table_size) {
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ret = grow_refcount_table(bs, refcount_table_index + 1);
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if (ret < 0) |
207 |
return ret;
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} |
209 |
|
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/* Load or allocate the refcount block */
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refcount_block_offset = s->refcount_table[refcount_table_index]; |
212 |
if (!refcount_block_offset) {
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if (cache_refcount_updates) {
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write_refcount_block(s); |
215 |
cache_refcount_updates = 0;
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} |
217 |
/* create a new refcount block */
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/* Note: we cannot update the refcount now to avoid recursion */
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offset = alloc_clusters_noref(bs, s->cluster_size); |
220 |
memset(s->refcount_block_cache, 0, s->cluster_size);
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ret = bdrv_pwrite(s->hd, offset, s->refcount_block_cache, s->cluster_size); |
222 |
if (ret != s->cluster_size)
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return -EINVAL;
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s->refcount_table[refcount_table_index] = offset; |
225 |
data64 = cpu_to_be64(offset); |
226 |
ret = bdrv_pwrite(s->hd, s->refcount_table_offset + |
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refcount_table_index * sizeof(uint64_t),
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&data64, sizeof(data64));
|
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if (ret != sizeof(data64)) |
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return -EINVAL;
|
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|
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refcount_block_offset = offset; |
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s->refcount_block_cache_offset = offset; |
234 |
update_refcount(bs, offset, s->cluster_size, 1);
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cache_refcount_updates = cache; |
236 |
} else {
|
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if (refcount_block_offset != s->refcount_block_cache_offset) {
|
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if (load_refcount_block(bs, refcount_block_offset) < 0) |
239 |
return -EIO;
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} |
241 |
} |
242 |
|
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return refcount_block_offset;
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} |
245 |
|
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#define REFCOUNTS_PER_SECTOR (512 >> REFCOUNT_SHIFT) |
247 |
static int write_refcount_block_entries(BDRVQcowState *s, |
248 |
int64_t refcount_block_offset, int first_index, int last_index) |
249 |
{ |
250 |
size_t size; |
251 |
|
252 |
if (cache_refcount_updates) {
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return 0; |
254 |
} |
255 |
|
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first_index &= ~(REFCOUNTS_PER_SECTOR - 1);
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last_index = (last_index + REFCOUNTS_PER_SECTOR) |
258 |
& ~(REFCOUNTS_PER_SECTOR - 1);
|
259 |
|
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size = (last_index - first_index) << REFCOUNT_SHIFT; |
261 |
if (bdrv_pwrite(s->hd,
|
262 |
refcount_block_offset + (first_index << REFCOUNT_SHIFT), |
263 |
&s->refcount_block_cache[first_index], size) != size) |
264 |
{ |
265 |
return -EIO;
|
266 |
} |
267 |
|
268 |
return 0; |
269 |
} |
270 |
|
271 |
/* XXX: cache several refcount block clusters ? */
|
272 |
static int update_refcount(BlockDriverState *bs, |
273 |
int64_t offset, int64_t length, |
274 |
int addend)
|
275 |
{ |
276 |
BDRVQcowState *s = bs->opaque; |
277 |
int64_t start, last, cluster_offset; |
278 |
int64_t refcount_block_offset = 0;
|
279 |
int64_t table_index = -1, old_table_index;
|
280 |
int first_index = -1, last_index = -1; |
281 |
int ret;
|
282 |
|
283 |
#ifdef DEBUG_ALLOC2
|
284 |
printf("update_refcount: offset=%" PRId64 " size=%" PRId64 " addend=%d\n", |
285 |
offset, length, addend); |
286 |
#endif
|
287 |
if (length <= 0) |
288 |
return -EINVAL;
|
289 |
start = offset & ~(s->cluster_size - 1);
|
290 |
last = (offset + length - 1) & ~(s->cluster_size - 1); |
291 |
for(cluster_offset = start; cluster_offset <= last;
|
292 |
cluster_offset += s->cluster_size) |
293 |
{ |
294 |
int block_index, refcount;
|
295 |
int64_t cluster_index = cluster_offset >> s->cluster_bits; |
296 |
int64_t new_block; |
297 |
|
298 |
/* Only write refcount block to disk when we are done with it */
|
299 |
old_table_index = table_index; |
300 |
table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); |
301 |
if ((old_table_index >= 0) && (table_index != old_table_index)) { |
302 |
|
303 |
if (write_refcount_block_entries(s, refcount_block_offset,
|
304 |
first_index, last_index) < 0)
|
305 |
{ |
306 |
return -EIO;
|
307 |
} |
308 |
|
309 |
first_index = -1;
|
310 |
last_index = -1;
|
311 |
} |
312 |
|
313 |
/* Load the refcount block and allocate it if needed */
|
314 |
new_block = alloc_refcount_block(bs, cluster_index); |
315 |
if (new_block < 0) { |
316 |
ret = new_block; |
317 |
goto fail;
|
318 |
} |
319 |
refcount_block_offset = new_block; |
320 |
|
321 |
/* we can update the count and save it */
|
322 |
block_index = cluster_index & |
323 |
((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); |
324 |
if (first_index == -1 || block_index < first_index) { |
325 |
first_index = block_index; |
326 |
} |
327 |
if (block_index > last_index) {
|
328 |
last_index = block_index; |
329 |
} |
330 |
|
331 |
refcount = be16_to_cpu(s->refcount_block_cache[block_index]); |
332 |
refcount += addend; |
333 |
if (refcount < 0 || refcount > 0xffff) { |
334 |
ret = -EINVAL; |
335 |
goto fail;
|
336 |
} |
337 |
if (refcount == 0 && cluster_index < s->free_cluster_index) { |
338 |
s->free_cluster_index = cluster_index; |
339 |
} |
340 |
s->refcount_block_cache[block_index] = cpu_to_be16(refcount); |
341 |
} |
342 |
|
343 |
ret = 0;
|
344 |
fail:
|
345 |
|
346 |
/* Write last changed block to disk */
|
347 |
if (refcount_block_offset != 0) { |
348 |
if (write_refcount_block_entries(s, refcount_block_offset,
|
349 |
first_index, last_index) < 0)
|
350 |
{ |
351 |
return ret < 0 ? ret : -EIO; |
352 |
} |
353 |
} |
354 |
|
355 |
/*
|
356 |
* Try do undo any updates if an error is returned (This may succeed in
|
357 |
* some cases like ENOSPC for allocating a new refcount block)
|
358 |
*/
|
359 |
if (ret < 0) { |
360 |
int dummy;
|
361 |
dummy = update_refcount(bs, offset, cluster_offset - offset, -addend); |
362 |
} |
363 |
|
364 |
return ret;
|
365 |
} |
366 |
|
367 |
/* addend must be 1 or -1 */
|
368 |
static int update_cluster_refcount(BlockDriverState *bs, |
369 |
int64_t cluster_index, |
370 |
int addend)
|
371 |
{ |
372 |
BDRVQcowState *s = bs->opaque; |
373 |
int ret;
|
374 |
|
375 |
ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend);
|
376 |
if (ret < 0) { |
377 |
return ret;
|
378 |
} |
379 |
|
380 |
return get_refcount(bs, cluster_index);
|
381 |
} |
382 |
|
383 |
|
384 |
|
385 |
/*********************************************************/
|
386 |
/* cluster allocation functions */
|
387 |
|
388 |
|
389 |
|
390 |
/* return < 0 if error */
|
391 |
static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size)
|
392 |
{ |
393 |
BDRVQcowState *s = bs->opaque; |
394 |
int i, nb_clusters;
|
395 |
|
396 |
nb_clusters = size_to_clusters(s, size); |
397 |
retry:
|
398 |
for(i = 0; i < nb_clusters; i++) { |
399 |
int64_t i = s->free_cluster_index++; |
400 |
if (get_refcount(bs, i) != 0) |
401 |
goto retry;
|
402 |
} |
403 |
#ifdef DEBUG_ALLOC2
|
404 |
printf("alloc_clusters: size=%" PRId64 " -> %" PRId64 "\n", |
405 |
size, |
406 |
(s->free_cluster_index - nb_clusters) << s->cluster_bits); |
407 |
#endif
|
408 |
return (s->free_cluster_index - nb_clusters) << s->cluster_bits;
|
409 |
} |
410 |
|
411 |
int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size) |
412 |
{ |
413 |
int64_t offset; |
414 |
|
415 |
offset = alloc_clusters_noref(bs, size); |
416 |
update_refcount(bs, offset, size, 1);
|
417 |
return offset;
|
418 |
} |
419 |
|
420 |
/* only used to allocate compressed sectors. We try to allocate
|
421 |
contiguous sectors. size must be <= cluster_size */
|
422 |
int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
|
423 |
{ |
424 |
BDRVQcowState *s = bs->opaque; |
425 |
int64_t offset, cluster_offset; |
426 |
int free_in_cluster;
|
427 |
|
428 |
assert(size > 0 && size <= s->cluster_size);
|
429 |
if (s->free_byte_offset == 0) { |
430 |
s->free_byte_offset = qcow2_alloc_clusters(bs, s->cluster_size); |
431 |
} |
432 |
redo:
|
433 |
free_in_cluster = s->cluster_size - |
434 |
(s->free_byte_offset & (s->cluster_size - 1));
|
435 |
if (size <= free_in_cluster) {
|
436 |
/* enough space in current cluster */
|
437 |
offset = s->free_byte_offset; |
438 |
s->free_byte_offset += size; |
439 |
free_in_cluster -= size; |
440 |
if (free_in_cluster == 0) |
441 |
s->free_byte_offset = 0;
|
442 |
if ((offset & (s->cluster_size - 1)) != 0) |
443 |
update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
|
444 |
} else {
|
445 |
offset = qcow2_alloc_clusters(bs, s->cluster_size); |
446 |
cluster_offset = s->free_byte_offset & ~(s->cluster_size - 1);
|
447 |
if ((cluster_offset + s->cluster_size) == offset) {
|
448 |
/* we are lucky: contiguous data */
|
449 |
offset = s->free_byte_offset; |
450 |
update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
|
451 |
s->free_byte_offset += size; |
452 |
} else {
|
453 |
s->free_byte_offset = offset; |
454 |
goto redo;
|
455 |
} |
456 |
} |
457 |
return offset;
|
458 |
} |
459 |
|
460 |
void qcow2_free_clusters(BlockDriverState *bs,
|
461 |
int64_t offset, int64_t size) |
462 |
{ |
463 |
update_refcount(bs, offset, size, -1);
|
464 |
} |
465 |
|
466 |
/*
|
467 |
* free_any_clusters
|
468 |
*
|
469 |
* free clusters according to its type: compressed or not
|
470 |
*
|
471 |
*/
|
472 |
|
473 |
void qcow2_free_any_clusters(BlockDriverState *bs,
|
474 |
uint64_t cluster_offset, int nb_clusters)
|
475 |
{ |
476 |
BDRVQcowState *s = bs->opaque; |
477 |
|
478 |
/* free the cluster */
|
479 |
|
480 |
if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
|
481 |
int nb_csectors;
|
482 |
nb_csectors = ((cluster_offset >> s->csize_shift) & |
483 |
s->csize_mask) + 1;
|
484 |
qcow2_free_clusters(bs, |
485 |
(cluster_offset & s->cluster_offset_mask) & ~511,
|
486 |
nb_csectors * 512);
|
487 |
return;
|
488 |
} |
489 |
|
490 |
qcow2_free_clusters(bs, cluster_offset, nb_clusters << s->cluster_bits); |
491 |
|
492 |
return;
|
493 |
} |
494 |
|
495 |
|
496 |
|
497 |
/*********************************************************/
|
498 |
/* snapshots and image creation */
|
499 |
|
500 |
|
501 |
|
502 |
void qcow2_create_refcount_update(QCowCreateState *s, int64_t offset,
|
503 |
int64_t size) |
504 |
{ |
505 |
int refcount;
|
506 |
int64_t start, last, cluster_offset; |
507 |
uint16_t *p; |
508 |
|
509 |
start = offset & ~(s->cluster_size - 1);
|
510 |
last = (offset + size - 1) & ~(s->cluster_size - 1); |
511 |
for(cluster_offset = start; cluster_offset <= last;
|
512 |
cluster_offset += s->cluster_size) { |
513 |
p = &s->refcount_block[cluster_offset >> s->cluster_bits]; |
514 |
refcount = be16_to_cpu(*p); |
515 |
refcount++; |
516 |
*p = cpu_to_be16(refcount); |
517 |
} |
518 |
} |
519 |
|
520 |
/* update the refcounts of snapshots and the copied flag */
|
521 |
int qcow2_update_snapshot_refcount(BlockDriverState *bs,
|
522 |
int64_t l1_table_offset, int l1_size, int addend) |
523 |
{ |
524 |
BDRVQcowState *s = bs->opaque; |
525 |
uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated; |
526 |
int64_t old_offset, old_l2_offset; |
527 |
int l2_size, i, j, l1_modified, l2_modified, nb_csectors, refcount;
|
528 |
|
529 |
qcow2_l2_cache_reset(bs); |
530 |
cache_refcount_updates = 1;
|
531 |
|
532 |
l2_table = NULL;
|
533 |
l1_table = NULL;
|
534 |
l1_size2 = l1_size * sizeof(uint64_t);
|
535 |
if (l1_table_offset != s->l1_table_offset) {
|
536 |
if (l1_size2 != 0) { |
537 |
l1_table = qemu_mallocz(align_offset(l1_size2, 512));
|
538 |
} else {
|
539 |
l1_table = NULL;
|
540 |
} |
541 |
l1_allocated = 1;
|
542 |
if (bdrv_pread(s->hd, l1_table_offset,
|
543 |
l1_table, l1_size2) != l1_size2) |
544 |
goto fail;
|
545 |
for(i = 0;i < l1_size; i++) |
546 |
be64_to_cpus(&l1_table[i]); |
547 |
} else {
|
548 |
assert(l1_size == s->l1_size); |
549 |
l1_table = s->l1_table; |
550 |
l1_allocated = 0;
|
551 |
} |
552 |
|
553 |
l2_size = s->l2_size * sizeof(uint64_t);
|
554 |
l2_table = qemu_malloc(l2_size); |
555 |
l1_modified = 0;
|
556 |
for(i = 0; i < l1_size; i++) { |
557 |
l2_offset = l1_table[i]; |
558 |
if (l2_offset) {
|
559 |
old_l2_offset = l2_offset; |
560 |
l2_offset &= ~QCOW_OFLAG_COPIED; |
561 |
l2_modified = 0;
|
562 |
if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size)
|
563 |
goto fail;
|
564 |
for(j = 0; j < s->l2_size; j++) { |
565 |
offset = be64_to_cpu(l2_table[j]); |
566 |
if (offset != 0) { |
567 |
old_offset = offset; |
568 |
offset &= ~QCOW_OFLAG_COPIED; |
569 |
if (offset & QCOW_OFLAG_COMPRESSED) {
|
570 |
nb_csectors = ((offset >> s->csize_shift) & |
571 |
s->csize_mask) + 1;
|
572 |
if (addend != 0) |
573 |
update_refcount(bs, (offset & s->cluster_offset_mask) & ~511,
|
574 |
nb_csectors * 512, addend);
|
575 |
/* compressed clusters are never modified */
|
576 |
refcount = 2;
|
577 |
} else {
|
578 |
if (addend != 0) { |
579 |
refcount = update_cluster_refcount(bs, offset >> s->cluster_bits, addend); |
580 |
} else {
|
581 |
refcount = get_refcount(bs, offset >> s->cluster_bits); |
582 |
} |
583 |
} |
584 |
|
585 |
if (refcount == 1) { |
586 |
offset |= QCOW_OFLAG_COPIED; |
587 |
} |
588 |
if (offset != old_offset) {
|
589 |
l2_table[j] = cpu_to_be64(offset); |
590 |
l2_modified = 1;
|
591 |
} |
592 |
} |
593 |
} |
594 |
if (l2_modified) {
|
595 |
if (bdrv_pwrite(s->hd,
|
596 |
l2_offset, l2_table, l2_size) != l2_size) |
597 |
goto fail;
|
598 |
} |
599 |
|
600 |
if (addend != 0) { |
601 |
refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend); |
602 |
} else {
|
603 |
refcount = get_refcount(bs, l2_offset >> s->cluster_bits); |
604 |
} |
605 |
if (refcount == 1) { |
606 |
l2_offset |= QCOW_OFLAG_COPIED; |
607 |
} |
608 |
if (l2_offset != old_l2_offset) {
|
609 |
l1_table[i] = l2_offset; |
610 |
l1_modified = 1;
|
611 |
} |
612 |
} |
613 |
} |
614 |
if (l1_modified) {
|
615 |
for(i = 0; i < l1_size; i++) |
616 |
cpu_to_be64s(&l1_table[i]); |
617 |
if (bdrv_pwrite(s->hd, l1_table_offset, l1_table,
|
618 |
l1_size2) != l1_size2) |
619 |
goto fail;
|
620 |
for(i = 0; i < l1_size; i++) |
621 |
be64_to_cpus(&l1_table[i]); |
622 |
} |
623 |
if (l1_allocated)
|
624 |
qemu_free(l1_table); |
625 |
qemu_free(l2_table); |
626 |
cache_refcount_updates = 0;
|
627 |
write_refcount_block(s); |
628 |
return 0; |
629 |
fail:
|
630 |
if (l1_allocated)
|
631 |
qemu_free(l1_table); |
632 |
qemu_free(l2_table); |
633 |
cache_refcount_updates = 0;
|
634 |
write_refcount_block(s); |
635 |
return -EIO;
|
636 |
} |
637 |
|
638 |
|
639 |
|
640 |
|
641 |
/*********************************************************/
|
642 |
/* refcount checking functions */
|
643 |
|
644 |
|
645 |
|
646 |
/*
|
647 |
* Increases the refcount for a range of clusters in a given refcount table.
|
648 |
* This is used to construct a temporary refcount table out of L1 and L2 tables
|
649 |
* which can be compared the the refcount table saved in the image.
|
650 |
*
|
651 |
* Returns the number of errors in the image that were found
|
652 |
*/
|
653 |
static int inc_refcounts(BlockDriverState *bs, |
654 |
uint16_t *refcount_table, |
655 |
int refcount_table_size,
|
656 |
int64_t offset, int64_t size) |
657 |
{ |
658 |
BDRVQcowState *s = bs->opaque; |
659 |
int64_t start, last, cluster_offset; |
660 |
int k;
|
661 |
int errors = 0; |
662 |
|
663 |
if (size <= 0) |
664 |
return 0; |
665 |
|
666 |
start = offset & ~(s->cluster_size - 1);
|
667 |
last = (offset + size - 1) & ~(s->cluster_size - 1); |
668 |
for(cluster_offset = start; cluster_offset <= last;
|
669 |
cluster_offset += s->cluster_size) { |
670 |
k = cluster_offset >> s->cluster_bits; |
671 |
if (k < 0 || k >= refcount_table_size) { |
672 |
fprintf(stderr, "ERROR: invalid cluster offset=0x%" PRIx64 "\n", |
673 |
cluster_offset); |
674 |
errors++; |
675 |
} else {
|
676 |
if (++refcount_table[k] == 0) { |
677 |
fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64
|
678 |
"\n", cluster_offset);
|
679 |
errors++; |
680 |
} |
681 |
} |
682 |
} |
683 |
|
684 |
return errors;
|
685 |
} |
686 |
|
687 |
/*
|
688 |
* Increases the refcount in the given refcount table for the all clusters
|
689 |
* referenced in the L2 table. While doing so, performs some checks on L2
|
690 |
* entries.
|
691 |
*
|
692 |
* Returns the number of errors found by the checks or -errno if an internal
|
693 |
* error occurred.
|
694 |
*/
|
695 |
static int check_refcounts_l2(BlockDriverState *bs, |
696 |
uint16_t *refcount_table, int refcount_table_size, int64_t l2_offset,
|
697 |
int check_copied)
|
698 |
{ |
699 |
BDRVQcowState *s = bs->opaque; |
700 |
uint64_t *l2_table, offset; |
701 |
int i, l2_size, nb_csectors, refcount;
|
702 |
int errors = 0; |
703 |
|
704 |
/* Read L2 table from disk */
|
705 |
l2_size = s->l2_size * sizeof(uint64_t);
|
706 |
l2_table = qemu_malloc(l2_size); |
707 |
|
708 |
if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size)
|
709 |
goto fail;
|
710 |
|
711 |
/* Do the actual checks */
|
712 |
for(i = 0; i < s->l2_size; i++) { |
713 |
offset = be64_to_cpu(l2_table[i]); |
714 |
if (offset != 0) { |
715 |
if (offset & QCOW_OFLAG_COMPRESSED) {
|
716 |
/* Compressed clusters don't have QCOW_OFLAG_COPIED */
|
717 |
if (offset & QCOW_OFLAG_COPIED) {
|
718 |
fprintf(stderr, "ERROR: cluster %" PRId64 ": " |
719 |
"copied flag must never be set for compressed "
|
720 |
"clusters\n", offset >> s->cluster_bits);
|
721 |
offset &= ~QCOW_OFLAG_COPIED; |
722 |
errors++; |
723 |
} |
724 |
|
725 |
/* Mark cluster as used */
|
726 |
nb_csectors = ((offset >> s->csize_shift) & |
727 |
s->csize_mask) + 1;
|
728 |
offset &= s->cluster_offset_mask; |
729 |
errors += inc_refcounts(bs, refcount_table, |
730 |
refcount_table_size, |
731 |
offset & ~511, nb_csectors * 512); |
732 |
} else {
|
733 |
/* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
|
734 |
if (check_copied) {
|
735 |
uint64_t entry = offset; |
736 |
offset &= ~QCOW_OFLAG_COPIED; |
737 |
refcount = get_refcount(bs, offset >> s->cluster_bits); |
738 |
if ((refcount == 1) != ((entry & QCOW_OFLAG_COPIED) != 0)) { |
739 |
fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"
|
740 |
PRIx64 " refcount=%d\n", entry, refcount);
|
741 |
errors++; |
742 |
} |
743 |
} |
744 |
|
745 |
/* Mark cluster as used */
|
746 |
offset &= ~QCOW_OFLAG_COPIED; |
747 |
errors += inc_refcounts(bs, refcount_table, |
748 |
refcount_table_size, |
749 |
offset, s->cluster_size); |
750 |
|
751 |
/* Correct offsets are cluster aligned */
|
752 |
if (offset & (s->cluster_size - 1)) { |
753 |
fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not " |
754 |
"properly aligned; L2 entry corrupted.\n", offset);
|
755 |
errors++; |
756 |
} |
757 |
} |
758 |
} |
759 |
} |
760 |
|
761 |
qemu_free(l2_table); |
762 |
return errors;
|
763 |
|
764 |
fail:
|
765 |
fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
|
766 |
qemu_free(l2_table); |
767 |
return -EIO;
|
768 |
} |
769 |
|
770 |
/*
|
771 |
* Increases the refcount for the L1 table, its L2 tables and all referenced
|
772 |
* clusters in the given refcount table. While doing so, performs some checks
|
773 |
* on L1 and L2 entries.
|
774 |
*
|
775 |
* Returns the number of errors found by the checks or -errno if an internal
|
776 |
* error occurred.
|
777 |
*/
|
778 |
static int check_refcounts_l1(BlockDriverState *bs, |
779 |
uint16_t *refcount_table, |
780 |
int refcount_table_size,
|
781 |
int64_t l1_table_offset, int l1_size,
|
782 |
int check_copied)
|
783 |
{ |
784 |
BDRVQcowState *s = bs->opaque; |
785 |
uint64_t *l1_table, l2_offset, l1_size2; |
786 |
int i, refcount, ret;
|
787 |
int errors = 0; |
788 |
|
789 |
l1_size2 = l1_size * sizeof(uint64_t);
|
790 |
|
791 |
/* Mark L1 table as used */
|
792 |
errors += inc_refcounts(bs, refcount_table, refcount_table_size, |
793 |
l1_table_offset, l1_size2); |
794 |
|
795 |
/* Read L1 table entries from disk */
|
796 |
if (l1_size2 == 0) { |
797 |
l1_table = NULL;
|
798 |
} else {
|
799 |
l1_table = qemu_malloc(l1_size2); |
800 |
if (bdrv_pread(s->hd, l1_table_offset,
|
801 |
l1_table, l1_size2) != l1_size2) |
802 |
goto fail;
|
803 |
for(i = 0;i < l1_size; i++) |
804 |
be64_to_cpus(&l1_table[i]); |
805 |
} |
806 |
|
807 |
/* Do the actual checks */
|
808 |
for(i = 0; i < l1_size; i++) { |
809 |
l2_offset = l1_table[i]; |
810 |
if (l2_offset) {
|
811 |
/* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
|
812 |
if (check_copied) {
|
813 |
refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED) |
814 |
>> s->cluster_bits); |
815 |
if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) { |
816 |
fprintf(stderr, "ERROR OFLAG_COPIED: l2_offset=%" PRIx64
|
817 |
" refcount=%d\n", l2_offset, refcount);
|
818 |
errors++; |
819 |
} |
820 |
} |
821 |
|
822 |
/* Mark L2 table as used */
|
823 |
l2_offset &= ~QCOW_OFLAG_COPIED; |
824 |
errors += inc_refcounts(bs, refcount_table, |
825 |
refcount_table_size, |
826 |
l2_offset, |
827 |
s->cluster_size); |
828 |
|
829 |
/* L2 tables are cluster aligned */
|
830 |
if (l2_offset & (s->cluster_size - 1)) { |
831 |
fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not " |
832 |
"cluster aligned; L1 entry corrupted\n", l2_offset);
|
833 |
errors++; |
834 |
} |
835 |
|
836 |
/* Process and check L2 entries */
|
837 |
ret = check_refcounts_l2(bs, refcount_table, refcount_table_size, |
838 |
l2_offset, check_copied); |
839 |
if (ret < 0) { |
840 |
goto fail;
|
841 |
} |
842 |
errors += ret; |
843 |
} |
844 |
} |
845 |
qemu_free(l1_table); |
846 |
return errors;
|
847 |
|
848 |
fail:
|
849 |
fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
|
850 |
qemu_free(l1_table); |
851 |
return -EIO;
|
852 |
} |
853 |
|
854 |
/*
|
855 |
* Checks an image for refcount consistency.
|
856 |
*
|
857 |
* Returns 0 if no errors are found, the number of errors in case the image is
|
858 |
* detected as corrupted, and -errno when an internal error occured.
|
859 |
*/
|
860 |
int qcow2_check_refcounts(BlockDriverState *bs)
|
861 |
{ |
862 |
BDRVQcowState *s = bs->opaque; |
863 |
int64_t size; |
864 |
int nb_clusters, refcount1, refcount2, i;
|
865 |
QCowSnapshot *sn; |
866 |
uint16_t *refcount_table; |
867 |
int ret, errors = 0; |
868 |
|
869 |
size = bdrv_getlength(s->hd); |
870 |
nb_clusters = size_to_clusters(s, size); |
871 |
refcount_table = qemu_mallocz(nb_clusters * sizeof(uint16_t));
|
872 |
|
873 |
/* header */
|
874 |
errors += inc_refcounts(bs, refcount_table, nb_clusters, |
875 |
0, s->cluster_size);
|
876 |
|
877 |
/* current L1 table */
|
878 |
ret = check_refcounts_l1(bs, refcount_table, nb_clusters, |
879 |
s->l1_table_offset, s->l1_size, 1);
|
880 |
if (ret < 0) { |
881 |
return ret;
|
882 |
} |
883 |
errors += ret; |
884 |
|
885 |
/* snapshots */
|
886 |
for(i = 0; i < s->nb_snapshots; i++) { |
887 |
sn = s->snapshots + i; |
888 |
check_refcounts_l1(bs, refcount_table, nb_clusters, |
889 |
sn->l1_table_offset, sn->l1_size, 0);
|
890 |
} |
891 |
errors += inc_refcounts(bs, refcount_table, nb_clusters, |
892 |
s->snapshots_offset, s->snapshots_size); |
893 |
|
894 |
/* refcount data */
|
895 |
errors += inc_refcounts(bs, refcount_table, nb_clusters, |
896 |
s->refcount_table_offset, |
897 |
s->refcount_table_size * sizeof(uint64_t));
|
898 |
for(i = 0; i < s->refcount_table_size; i++) { |
899 |
int64_t offset; |
900 |
offset = s->refcount_table[i]; |
901 |
if (offset != 0) { |
902 |
errors += inc_refcounts(bs, refcount_table, nb_clusters, |
903 |
offset, s->cluster_size); |
904 |
} |
905 |
} |
906 |
|
907 |
/* compare ref counts */
|
908 |
for(i = 0; i < nb_clusters; i++) { |
909 |
refcount1 = get_refcount(bs, i); |
910 |
refcount2 = refcount_table[i]; |
911 |
if (refcount1 != refcount2) {
|
912 |
fprintf(stderr, "ERROR cluster %d refcount=%d reference=%d\n",
|
913 |
i, refcount1, refcount2); |
914 |
errors++; |
915 |
} |
916 |
} |
917 |
|
918 |
qemu_free(refcount_table); |
919 |
|
920 |
return errors;
|
921 |
} |
922 |
|