root / block / qcow2-cluster.c @ 22f0dd29
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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 <zlib.h> |
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#include "qemu-common.h" |
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#include "block/block_int.h" |
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#include "block/qcow2.h" |
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#include "trace.h" |
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int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
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bool exact_size)
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{ |
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BDRVQcowState *s = bs->opaque; |
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int new_l1_size2, ret, i;
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uint64_t *new_l1_table; |
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int64_t new_l1_table_offset, new_l1_size; |
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uint8_t data[12];
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|
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if (min_size <= s->l1_size)
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return 0; |
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|
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if (exact_size) {
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new_l1_size = min_size; |
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} else {
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/* Bump size up to reduce the number of times we have to grow */
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new_l1_size = s->l1_size; |
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if (new_l1_size == 0) { |
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new_l1_size = 1;
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} |
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while (min_size > new_l1_size) {
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new_l1_size = (new_l1_size * 3 + 1) / 2; |
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} |
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} |
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|
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if (new_l1_size > INT_MAX) {
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return -EFBIG;
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} |
60 |
|
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#ifdef DEBUG_ALLOC2
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fprintf(stderr, "grow l1_table from %d to %" PRId64 "\n", |
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s->l1_size, new_l1_size); |
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#endif
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new_l1_size2 = sizeof(uint64_t) * new_l1_size;
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new_l1_table = g_malloc0(align_offset(new_l1_size2, 512));
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memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t));
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|
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/* write new table (align to cluster) */
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BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ALLOC_TABLE); |
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new_l1_table_offset = qcow2_alloc_clusters(bs, new_l1_size2); |
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if (new_l1_table_offset < 0) { |
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g_free(new_l1_table); |
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return new_l1_table_offset;
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} |
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|
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ret = qcow2_cache_flush(bs, s->refcount_block_cache); |
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if (ret < 0) { |
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goto fail;
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} |
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|
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/* the L1 position has not yet been updated, so these clusters must
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* indeed be completely free */
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ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT, |
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new_l1_table_offset, new_l1_size2); |
87 |
if (ret < 0) { |
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goto fail;
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} |
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|
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BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_WRITE_TABLE); |
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for(i = 0; i < s->l1_size; i++) |
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new_l1_table[i] = cpu_to_be64(new_l1_table[i]); |
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ret = bdrv_pwrite_sync(bs->file, new_l1_table_offset, new_l1_table, new_l1_size2); |
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if (ret < 0) |
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goto fail;
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for(i = 0; i < s->l1_size; i++) |
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new_l1_table[i] = be64_to_cpu(new_l1_table[i]); |
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|
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/* set new table */
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BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ACTIVATE_TABLE); |
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cpu_to_be32w((uint32_t*)data, new_l1_size); |
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cpu_to_be64wu((uint64_t*)(data + 4), new_l1_table_offset);
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ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_size), data,sizeof(data));
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if (ret < 0) { |
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goto fail;
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} |
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g_free(s->l1_table); |
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qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t),
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QCOW2_DISCARD_OTHER); |
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s->l1_table_offset = new_l1_table_offset; |
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s->l1_table = new_l1_table; |
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s->l1_size = new_l1_size; |
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return 0; |
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fail:
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g_free(new_l1_table); |
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qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2, |
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QCOW2_DISCARD_OTHER); |
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return ret;
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} |
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|
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/*
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* l2_load
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*
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* Loads a L2 table into memory. If the table is in the cache, the cache
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* is used; otherwise the L2 table is loaded from the image file.
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*
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* Returns a pointer to the L2 table on success, or NULL if the read from
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* the image file failed.
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*/
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|
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static int l2_load(BlockDriverState *bs, uint64_t l2_offset, |
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uint64_t **l2_table) |
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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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ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, (void**) l2_table);
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return ret;
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} |
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/*
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* Writes one sector of the L1 table to the disk (can't update single entries
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* and we really don't want bdrv_pread to perform a read-modify-write)
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*/
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#define L1_ENTRIES_PER_SECTOR (512 / 8) |
148 |
int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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uint64_t buf[L1_ENTRIES_PER_SECTOR]; |
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int l1_start_index;
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int i, ret;
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|
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l1_start_index = l1_index & ~(L1_ENTRIES_PER_SECTOR - 1);
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for (i = 0; i < L1_ENTRIES_PER_SECTOR; i++) { |
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buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]); |
158 |
} |
159 |
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ret = qcow2_pre_write_overlap_check(bs, |
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QCOW2_OL_DEFAULT & ~QCOW2_OL_ACTIVE_L1, |
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s->l1_table_offset + 8 * l1_start_index, sizeof(buf)); |
163 |
if (ret < 0) { |
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return ret;
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} |
166 |
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BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE); |
168 |
ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset + 8 * l1_start_index,
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buf, sizeof(buf));
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if (ret < 0) { |
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return ret;
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} |
173 |
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return 0; |
175 |
} |
176 |
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/*
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* l2_allocate
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*
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* Allocate a new l2 entry in the file. If l1_index points to an already
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* used entry in the L2 table (i.e. we are doing a copy on write for the L2
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* table) copy the contents of the old L2 table into the newly allocated one.
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* Otherwise the new table is initialized with zeros.
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*
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*/
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static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table) |
188 |
{ |
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BDRVQcowState *s = bs->opaque; |
190 |
uint64_t old_l2_offset; |
191 |
uint64_t *l2_table = NULL;
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int64_t l2_offset; |
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int ret;
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old_l2_offset = s->l1_table[l1_index]; |
196 |
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trace_qcow2_l2_allocate(bs, l1_index); |
198 |
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/* allocate a new l2 entry */
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l2_offset = qcow2_alloc_clusters(bs, s->l2_size * sizeof(uint64_t));
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if (l2_offset < 0) { |
203 |
ret = l2_offset; |
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goto fail;
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} |
206 |
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ret = qcow2_cache_flush(bs, s->refcount_block_cache); |
208 |
if (ret < 0) { |
209 |
goto fail;
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} |
211 |
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/* allocate a new entry in the l2 cache */
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trace_qcow2_l2_allocate_get_empty(bs, l1_index); |
215 |
ret = qcow2_cache_get_empty(bs, s->l2_table_cache, l2_offset, (void**) table);
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if (ret < 0) { |
217 |
goto fail;
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} |
219 |
|
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l2_table = *table; |
221 |
|
222 |
if ((old_l2_offset & L1E_OFFSET_MASK) == 0) { |
223 |
/* if there was no old l2 table, clear the new table */
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memset(l2_table, 0, s->l2_size * sizeof(uint64_t)); |
225 |
} else {
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uint64_t* old_table; |
227 |
|
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/* if there was an old l2 table, read it from the disk */
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BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ); |
230 |
ret = qcow2_cache_get(bs, s->l2_table_cache, |
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old_l2_offset & L1E_OFFSET_MASK, |
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(void**) &old_table);
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if (ret < 0) { |
234 |
goto fail;
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} |
236 |
|
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memcpy(l2_table, old_table, s->cluster_size); |
238 |
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ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &old_table);
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240 |
if (ret < 0) { |
241 |
goto fail;
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} |
243 |
} |
244 |
|
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/* write the l2 table to the file */
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BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE); |
247 |
|
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trace_qcow2_l2_allocate_write_l2(bs, l1_index); |
249 |
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); |
250 |
ret = qcow2_cache_flush(bs, s->l2_table_cache); |
251 |
if (ret < 0) { |
252 |
goto fail;
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253 |
} |
254 |
|
255 |
/* update the L1 entry */
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trace_qcow2_l2_allocate_write_l1(bs, l1_index); |
257 |
s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED; |
258 |
ret = qcow2_write_l1_entry(bs, l1_index); |
259 |
if (ret < 0) { |
260 |
goto fail;
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261 |
} |
262 |
|
263 |
*table = l2_table; |
264 |
trace_qcow2_l2_allocate_done(bs, l1_index, 0);
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265 |
return 0; |
266 |
|
267 |
fail:
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268 |
trace_qcow2_l2_allocate_done(bs, l1_index, ret); |
269 |
if (l2_table != NULL) { |
270 |
qcow2_cache_put(bs, s->l2_table_cache, (void**) table);
|
271 |
} |
272 |
s->l1_table[l1_index] = old_l2_offset; |
273 |
return ret;
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274 |
} |
275 |
|
276 |
/*
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277 |
* Checks how many clusters in a given L2 table are contiguous in the image
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278 |
* file. As soon as one of the flags in the bitmask stop_flags changes compared
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279 |
* to the first cluster, the search is stopped and the cluster is not counted
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280 |
* as contiguous. (This allows it, for example, to stop at the first compressed
|
281 |
* cluster which may require a different handling)
|
282 |
*/
|
283 |
static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size, |
284 |
uint64_t *l2_table, uint64_t start, uint64_t stop_flags) |
285 |
{ |
286 |
int i;
|
287 |
uint64_t mask = stop_flags | L2E_OFFSET_MASK | QCOW2_CLUSTER_COMPRESSED; |
288 |
uint64_t first_entry = be64_to_cpu(l2_table[0]);
|
289 |
uint64_t offset = first_entry & mask; |
290 |
|
291 |
if (!offset)
|
292 |
return 0; |
293 |
|
294 |
assert(qcow2_get_cluster_type(first_entry) != QCOW2_CLUSTER_COMPRESSED); |
295 |
|
296 |
for (i = start; i < start + nb_clusters; i++) {
|
297 |
uint64_t l2_entry = be64_to_cpu(l2_table[i]) & mask; |
298 |
if (offset + (uint64_t) i * cluster_size != l2_entry) {
|
299 |
break;
|
300 |
} |
301 |
} |
302 |
|
303 |
return (i - start);
|
304 |
} |
305 |
|
306 |
static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t *l2_table) |
307 |
{ |
308 |
int i;
|
309 |
|
310 |
for (i = 0; i < nb_clusters; i++) { |
311 |
int type = qcow2_get_cluster_type(be64_to_cpu(l2_table[i]));
|
312 |
|
313 |
if (type != QCOW2_CLUSTER_UNALLOCATED) {
|
314 |
break;
|
315 |
} |
316 |
} |
317 |
|
318 |
return i;
|
319 |
} |
320 |
|
321 |
/* The crypt function is compatible with the linux cryptoloop
|
322 |
algorithm for < 4 GB images. NOTE: out_buf == in_buf is
|
323 |
supported */
|
324 |
void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
|
325 |
uint8_t *out_buf, const uint8_t *in_buf,
|
326 |
int nb_sectors, int enc, |
327 |
const AES_KEY *key)
|
328 |
{ |
329 |
union {
|
330 |
uint64_t ll[2];
|
331 |
uint8_t b[16];
|
332 |
} ivec; |
333 |
int i;
|
334 |
|
335 |
for(i = 0; i < nb_sectors; i++) { |
336 |
ivec.ll[0] = cpu_to_le64(sector_num);
|
337 |
ivec.ll[1] = 0; |
338 |
AES_cbc_encrypt(in_buf, out_buf, 512, key,
|
339 |
ivec.b, enc); |
340 |
sector_num++; |
341 |
in_buf += 512;
|
342 |
out_buf += 512;
|
343 |
} |
344 |
} |
345 |
|
346 |
static int coroutine_fn copy_sectors(BlockDriverState *bs, |
347 |
uint64_t start_sect, |
348 |
uint64_t cluster_offset, |
349 |
int n_start, int n_end) |
350 |
{ |
351 |
BDRVQcowState *s = bs->opaque; |
352 |
QEMUIOVector qiov; |
353 |
struct iovec iov;
|
354 |
int n, ret;
|
355 |
|
356 |
/*
|
357 |
* If this is the last cluster and it is only partially used, we must only
|
358 |
* copy until the end of the image, or bdrv_check_request will fail for the
|
359 |
* bdrv_read/write calls below.
|
360 |
*/
|
361 |
if (start_sect + n_end > bs->total_sectors) {
|
362 |
n_end = bs->total_sectors - start_sect; |
363 |
} |
364 |
|
365 |
n = n_end - n_start; |
366 |
if (n <= 0) { |
367 |
return 0; |
368 |
} |
369 |
|
370 |
iov.iov_len = n * BDRV_SECTOR_SIZE; |
371 |
iov.iov_base = qemu_blockalign(bs, iov.iov_len); |
372 |
|
373 |
qemu_iovec_init_external(&qiov, &iov, 1);
|
374 |
|
375 |
BLKDBG_EVENT(bs->file, BLKDBG_COW_READ); |
376 |
|
377 |
/* Call .bdrv_co_readv() directly instead of using the public block-layer
|
378 |
* interface. This avoids double I/O throttling and request tracking,
|
379 |
* which can lead to deadlock when block layer copy-on-read is enabled.
|
380 |
*/
|
381 |
ret = bs->drv->bdrv_co_readv(bs, start_sect + n_start, n, &qiov); |
382 |
if (ret < 0) { |
383 |
goto out;
|
384 |
} |
385 |
|
386 |
if (s->crypt_method) {
|
387 |
qcow2_encrypt_sectors(s, start_sect + n_start, |
388 |
iov.iov_base, iov.iov_base, n, 1,
|
389 |
&s->aes_encrypt_key); |
390 |
} |
391 |
|
392 |
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT, |
393 |
cluster_offset + n_start * BDRV_SECTOR_SIZE, n * BDRV_SECTOR_SIZE); |
394 |
if (ret < 0) { |
395 |
goto out;
|
396 |
} |
397 |
|
398 |
BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE); |
399 |
ret = bdrv_co_writev(bs->file, (cluster_offset >> 9) + n_start, n, &qiov);
|
400 |
if (ret < 0) { |
401 |
goto out;
|
402 |
} |
403 |
|
404 |
ret = 0;
|
405 |
out:
|
406 |
qemu_vfree(iov.iov_base); |
407 |
return ret;
|
408 |
} |
409 |
|
410 |
|
411 |
/*
|
412 |
* get_cluster_offset
|
413 |
*
|
414 |
* For a given offset of the disk image, find the cluster offset in
|
415 |
* qcow2 file. The offset is stored in *cluster_offset.
|
416 |
*
|
417 |
* on entry, *num is the number of contiguous sectors we'd like to
|
418 |
* access following offset.
|
419 |
*
|
420 |
* on exit, *num is the number of contiguous sectors we can read.
|
421 |
*
|
422 |
* Returns the cluster type (QCOW2_CLUSTER_*) on success, -errno in error
|
423 |
* cases.
|
424 |
*/
|
425 |
int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
|
426 |
int *num, uint64_t *cluster_offset)
|
427 |
{ |
428 |
BDRVQcowState *s = bs->opaque; |
429 |
unsigned int l2_index; |
430 |
uint64_t l1_index, l2_offset, *l2_table; |
431 |
int l1_bits, c;
|
432 |
unsigned int index_in_cluster, nb_clusters; |
433 |
uint64_t nb_available, nb_needed; |
434 |
int ret;
|
435 |
|
436 |
index_in_cluster = (offset >> 9) & (s->cluster_sectors - 1); |
437 |
nb_needed = *num + index_in_cluster; |
438 |
|
439 |
l1_bits = s->l2_bits + s->cluster_bits; |
440 |
|
441 |
/* compute how many bytes there are between the offset and
|
442 |
* the end of the l1 entry
|
443 |
*/
|
444 |
|
445 |
nb_available = (1ULL << l1_bits) - (offset & ((1ULL << l1_bits) - 1)); |
446 |
|
447 |
/* compute the number of available sectors */
|
448 |
|
449 |
nb_available = (nb_available >> 9) + index_in_cluster;
|
450 |
|
451 |
if (nb_needed > nb_available) {
|
452 |
nb_needed = nb_available; |
453 |
} |
454 |
|
455 |
*cluster_offset = 0;
|
456 |
|
457 |
/* seek the the l2 offset in the l1 table */
|
458 |
|
459 |
l1_index = offset >> l1_bits; |
460 |
if (l1_index >= s->l1_size) {
|
461 |
ret = QCOW2_CLUSTER_UNALLOCATED; |
462 |
goto out;
|
463 |
} |
464 |
|
465 |
l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; |
466 |
if (!l2_offset) {
|
467 |
ret = QCOW2_CLUSTER_UNALLOCATED; |
468 |
goto out;
|
469 |
} |
470 |
|
471 |
/* load the l2 table in memory */
|
472 |
|
473 |
ret = l2_load(bs, l2_offset, &l2_table); |
474 |
if (ret < 0) { |
475 |
return ret;
|
476 |
} |
477 |
|
478 |
/* find the cluster offset for the given disk offset */
|
479 |
|
480 |
l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
|
481 |
*cluster_offset = be64_to_cpu(l2_table[l2_index]); |
482 |
nb_clusters = size_to_clusters(s, nb_needed << 9);
|
483 |
|
484 |
ret = qcow2_get_cluster_type(*cluster_offset); |
485 |
switch (ret) {
|
486 |
case QCOW2_CLUSTER_COMPRESSED:
|
487 |
/* Compressed clusters can only be processed one by one */
|
488 |
c = 1;
|
489 |
*cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK; |
490 |
break;
|
491 |
case QCOW2_CLUSTER_ZERO:
|
492 |
if (s->qcow_version < 3) { |
493 |
return -EIO;
|
494 |
} |
495 |
c = count_contiguous_clusters(nb_clusters, s->cluster_size, |
496 |
&l2_table[l2_index], 0, QCOW_OFLAG_ZERO);
|
497 |
*cluster_offset = 0;
|
498 |
break;
|
499 |
case QCOW2_CLUSTER_UNALLOCATED:
|
500 |
/* how many empty clusters ? */
|
501 |
c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]); |
502 |
*cluster_offset = 0;
|
503 |
break;
|
504 |
case QCOW2_CLUSTER_NORMAL:
|
505 |
/* how many allocated clusters ? */
|
506 |
c = count_contiguous_clusters(nb_clusters, s->cluster_size, |
507 |
&l2_table[l2_index], 0, QCOW_OFLAG_ZERO);
|
508 |
*cluster_offset &= L2E_OFFSET_MASK; |
509 |
break;
|
510 |
default:
|
511 |
abort(); |
512 |
} |
513 |
|
514 |
qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
515 |
|
516 |
nb_available = (c * s->cluster_sectors); |
517 |
|
518 |
out:
|
519 |
if (nb_available > nb_needed)
|
520 |
nb_available = nb_needed; |
521 |
|
522 |
*num = nb_available - index_in_cluster; |
523 |
|
524 |
return ret;
|
525 |
} |
526 |
|
527 |
/*
|
528 |
* get_cluster_table
|
529 |
*
|
530 |
* for a given disk offset, load (and allocate if needed)
|
531 |
* the l2 table.
|
532 |
*
|
533 |
* the l2 table offset in the qcow2 file and the cluster index
|
534 |
* in the l2 table are given to the caller.
|
535 |
*
|
536 |
* Returns 0 on success, -errno in failure case
|
537 |
*/
|
538 |
static int get_cluster_table(BlockDriverState *bs, uint64_t offset, |
539 |
uint64_t **new_l2_table, |
540 |
int *new_l2_index)
|
541 |
{ |
542 |
BDRVQcowState *s = bs->opaque; |
543 |
unsigned int l2_index; |
544 |
uint64_t l1_index, l2_offset; |
545 |
uint64_t *l2_table = NULL;
|
546 |
int ret;
|
547 |
|
548 |
/* seek the the l2 offset in the l1 table */
|
549 |
|
550 |
l1_index = offset >> (s->l2_bits + s->cluster_bits); |
551 |
if (l1_index >= s->l1_size) {
|
552 |
ret = qcow2_grow_l1_table(bs, l1_index + 1, false); |
553 |
if (ret < 0) { |
554 |
return ret;
|
555 |
} |
556 |
} |
557 |
|
558 |
assert(l1_index < s->l1_size); |
559 |
l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK; |
560 |
|
561 |
/* seek the l2 table of the given l2 offset */
|
562 |
|
563 |
if (s->l1_table[l1_index] & QCOW_OFLAG_COPIED) {
|
564 |
/* load the l2 table in memory */
|
565 |
ret = l2_load(bs, l2_offset, &l2_table); |
566 |
if (ret < 0) { |
567 |
return ret;
|
568 |
} |
569 |
} else {
|
570 |
/* First allocate a new L2 table (and do COW if needed) */
|
571 |
ret = l2_allocate(bs, l1_index, &l2_table); |
572 |
if (ret < 0) { |
573 |
return ret;
|
574 |
} |
575 |
|
576 |
/* Then decrease the refcount of the old table */
|
577 |
if (l2_offset) {
|
578 |
qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
|
579 |
QCOW2_DISCARD_OTHER); |
580 |
} |
581 |
} |
582 |
|
583 |
/* find the cluster offset for the given disk offset */
|
584 |
|
585 |
l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
|
586 |
|
587 |
*new_l2_table = l2_table; |
588 |
*new_l2_index = l2_index; |
589 |
|
590 |
return 0; |
591 |
} |
592 |
|
593 |
/*
|
594 |
* alloc_compressed_cluster_offset
|
595 |
*
|
596 |
* For a given offset of the disk image, return cluster offset in
|
597 |
* qcow2 file.
|
598 |
*
|
599 |
* If the offset is not found, allocate a new compressed cluster.
|
600 |
*
|
601 |
* Return the cluster offset if successful,
|
602 |
* Return 0, otherwise.
|
603 |
*
|
604 |
*/
|
605 |
|
606 |
uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs, |
607 |
uint64_t offset, |
608 |
int compressed_size)
|
609 |
{ |
610 |
BDRVQcowState *s = bs->opaque; |
611 |
int l2_index, ret;
|
612 |
uint64_t *l2_table; |
613 |
int64_t cluster_offset; |
614 |
int nb_csectors;
|
615 |
|
616 |
ret = get_cluster_table(bs, offset, &l2_table, &l2_index); |
617 |
if (ret < 0) { |
618 |
return 0; |
619 |
} |
620 |
|
621 |
/* Compression can't overwrite anything. Fail if the cluster was already
|
622 |
* allocated. */
|
623 |
cluster_offset = be64_to_cpu(l2_table[l2_index]); |
624 |
if (cluster_offset & L2E_OFFSET_MASK) {
|
625 |
qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
626 |
return 0; |
627 |
} |
628 |
|
629 |
cluster_offset = qcow2_alloc_bytes(bs, compressed_size); |
630 |
if (cluster_offset < 0) { |
631 |
qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
632 |
return 0; |
633 |
} |
634 |
|
635 |
nb_csectors = ((cluster_offset + compressed_size - 1) >> 9) - |
636 |
(cluster_offset >> 9);
|
637 |
|
638 |
cluster_offset |= QCOW_OFLAG_COMPRESSED | |
639 |
((uint64_t)nb_csectors << s->csize_shift); |
640 |
|
641 |
/* update L2 table */
|
642 |
|
643 |
/* compressed clusters never have the copied flag */
|
644 |
|
645 |
BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED); |
646 |
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); |
647 |
l2_table[l2_index] = cpu_to_be64(cluster_offset); |
648 |
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
649 |
if (ret < 0) { |
650 |
return 0; |
651 |
} |
652 |
|
653 |
return cluster_offset;
|
654 |
} |
655 |
|
656 |
static int perform_cow(BlockDriverState *bs, QCowL2Meta *m, Qcow2COWRegion *r) |
657 |
{ |
658 |
BDRVQcowState *s = bs->opaque; |
659 |
int ret;
|
660 |
|
661 |
if (r->nb_sectors == 0) { |
662 |
return 0; |
663 |
} |
664 |
|
665 |
qemu_co_mutex_unlock(&s->lock); |
666 |
ret = copy_sectors(bs, m->offset / BDRV_SECTOR_SIZE, m->alloc_offset, |
667 |
r->offset / BDRV_SECTOR_SIZE, |
668 |
r->offset / BDRV_SECTOR_SIZE + r->nb_sectors); |
669 |
qemu_co_mutex_lock(&s->lock); |
670 |
|
671 |
if (ret < 0) { |
672 |
return ret;
|
673 |
} |
674 |
|
675 |
/*
|
676 |
* Before we update the L2 table to actually point to the new cluster, we
|
677 |
* need to be sure that the refcounts have been increased and COW was
|
678 |
* handled.
|
679 |
*/
|
680 |
qcow2_cache_depends_on_flush(s->l2_table_cache); |
681 |
|
682 |
return 0; |
683 |
} |
684 |
|
685 |
int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
|
686 |
{ |
687 |
BDRVQcowState *s = bs->opaque; |
688 |
int i, j = 0, l2_index, ret; |
689 |
uint64_t *old_cluster, *l2_table; |
690 |
uint64_t cluster_offset = m->alloc_offset; |
691 |
|
692 |
trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters); |
693 |
assert(m->nb_clusters > 0);
|
694 |
|
695 |
old_cluster = g_malloc(m->nb_clusters * sizeof(uint64_t));
|
696 |
|
697 |
/* copy content of unmodified sectors */
|
698 |
ret = perform_cow(bs, m, &m->cow_start); |
699 |
if (ret < 0) { |
700 |
goto err;
|
701 |
} |
702 |
|
703 |
ret = perform_cow(bs, m, &m->cow_end); |
704 |
if (ret < 0) { |
705 |
goto err;
|
706 |
} |
707 |
|
708 |
/* Update L2 table. */
|
709 |
if (s->use_lazy_refcounts) {
|
710 |
qcow2_mark_dirty(bs); |
711 |
} |
712 |
if (qcow2_need_accurate_refcounts(s)) {
|
713 |
qcow2_cache_set_dependency(bs, s->l2_table_cache, |
714 |
s->refcount_block_cache); |
715 |
} |
716 |
|
717 |
ret = get_cluster_table(bs, m->offset, &l2_table, &l2_index); |
718 |
if (ret < 0) { |
719 |
goto err;
|
720 |
} |
721 |
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); |
722 |
|
723 |
assert(l2_index + m->nb_clusters <= s->l2_size); |
724 |
for (i = 0; i < m->nb_clusters; i++) { |
725 |
/* if two concurrent writes happen to the same unallocated cluster
|
726 |
* each write allocates separate cluster and writes data concurrently.
|
727 |
* The first one to complete updates l2 table with pointer to its
|
728 |
* cluster the second one has to do RMW (which is done above by
|
729 |
* copy_sectors()), update l2 table with its cluster pointer and free
|
730 |
* old cluster. This is what this loop does */
|
731 |
if(l2_table[l2_index + i] != 0) |
732 |
old_cluster[j++] = l2_table[l2_index + i]; |
733 |
|
734 |
l2_table[l2_index + i] = cpu_to_be64((cluster_offset + |
735 |
(i << s->cluster_bits)) | QCOW_OFLAG_COPIED); |
736 |
} |
737 |
|
738 |
|
739 |
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
740 |
if (ret < 0) { |
741 |
goto err;
|
742 |
} |
743 |
|
744 |
/*
|
745 |
* If this was a COW, we need to decrease the refcount of the old cluster.
|
746 |
* Also flush bs->file to get the right order for L2 and refcount update.
|
747 |
*
|
748 |
* Don't discard clusters that reach a refcount of 0 (e.g. compressed
|
749 |
* clusters), the next write will reuse them anyway.
|
750 |
*/
|
751 |
if (j != 0) { |
752 |
for (i = 0; i < j; i++) { |
753 |
qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1,
|
754 |
QCOW2_DISCARD_NEVER); |
755 |
} |
756 |
} |
757 |
|
758 |
ret = 0;
|
759 |
err:
|
760 |
g_free(old_cluster); |
761 |
return ret;
|
762 |
} |
763 |
|
764 |
/*
|
765 |
* Returns the number of contiguous clusters that can be used for an allocating
|
766 |
* write, but require COW to be performed (this includes yet unallocated space,
|
767 |
* which must copy from the backing file)
|
768 |
*/
|
769 |
static int count_cow_clusters(BDRVQcowState *s, int nb_clusters, |
770 |
uint64_t *l2_table, int l2_index)
|
771 |
{ |
772 |
int i;
|
773 |
|
774 |
for (i = 0; i < nb_clusters; i++) { |
775 |
uint64_t l2_entry = be64_to_cpu(l2_table[l2_index + i]); |
776 |
int cluster_type = qcow2_get_cluster_type(l2_entry);
|
777 |
|
778 |
switch(cluster_type) {
|
779 |
case QCOW2_CLUSTER_NORMAL:
|
780 |
if (l2_entry & QCOW_OFLAG_COPIED) {
|
781 |
goto out;
|
782 |
} |
783 |
break;
|
784 |
case QCOW2_CLUSTER_UNALLOCATED:
|
785 |
case QCOW2_CLUSTER_COMPRESSED:
|
786 |
case QCOW2_CLUSTER_ZERO:
|
787 |
break;
|
788 |
default:
|
789 |
abort(); |
790 |
} |
791 |
} |
792 |
|
793 |
out:
|
794 |
assert(i <= nb_clusters); |
795 |
return i;
|
796 |
} |
797 |
|
798 |
/*
|
799 |
* Check if there already is an AIO write request in flight which allocates
|
800 |
* the same cluster. In this case we need to wait until the previous
|
801 |
* request has completed and updated the L2 table accordingly.
|
802 |
*
|
803 |
* Returns:
|
804 |
* 0 if there was no dependency. *cur_bytes indicates the number of
|
805 |
* bytes from guest_offset that can be read before the next
|
806 |
* dependency must be processed (or the request is complete)
|
807 |
*
|
808 |
* -EAGAIN if we had to wait for another request, previously gathered
|
809 |
* information on cluster allocation may be invalid now. The caller
|
810 |
* must start over anyway, so consider *cur_bytes undefined.
|
811 |
*/
|
812 |
static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset, |
813 |
uint64_t *cur_bytes, QCowL2Meta **m) |
814 |
{ |
815 |
BDRVQcowState *s = bs->opaque; |
816 |
QCowL2Meta *old_alloc; |
817 |
uint64_t bytes = *cur_bytes; |
818 |
|
819 |
QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) { |
820 |
|
821 |
uint64_t start = guest_offset; |
822 |
uint64_t end = start + bytes; |
823 |
uint64_t old_start = l2meta_cow_start(old_alloc); |
824 |
uint64_t old_end = l2meta_cow_end(old_alloc); |
825 |
|
826 |
if (end <= old_start || start >= old_end) {
|
827 |
/* No intersection */
|
828 |
} else {
|
829 |
if (start < old_start) {
|
830 |
/* Stop at the start of a running allocation */
|
831 |
bytes = old_start - start; |
832 |
} else {
|
833 |
bytes = 0;
|
834 |
} |
835 |
|
836 |
/* Stop if already an l2meta exists. After yielding, it wouldn't
|
837 |
* be valid any more, so we'd have to clean up the old L2Metas
|
838 |
* and deal with requests depending on them before starting to
|
839 |
* gather new ones. Not worth the trouble. */
|
840 |
if (bytes == 0 && *m) { |
841 |
*cur_bytes = 0;
|
842 |
return 0; |
843 |
} |
844 |
|
845 |
if (bytes == 0) { |
846 |
/* Wait for the dependency to complete. We need to recheck
|
847 |
* the free/allocated clusters when we continue. */
|
848 |
qemu_co_mutex_unlock(&s->lock); |
849 |
qemu_co_queue_wait(&old_alloc->dependent_requests); |
850 |
qemu_co_mutex_lock(&s->lock); |
851 |
return -EAGAIN;
|
852 |
} |
853 |
} |
854 |
} |
855 |
|
856 |
/* Make sure that existing clusters and new allocations are only used up to
|
857 |
* the next dependency if we shortened the request above */
|
858 |
*cur_bytes = bytes; |
859 |
|
860 |
return 0; |
861 |
} |
862 |
|
863 |
/*
|
864 |
* Checks how many already allocated clusters that don't require a copy on
|
865 |
* write there are at the given guest_offset (up to *bytes). If
|
866 |
* *host_offset is not zero, only physically contiguous clusters beginning at
|
867 |
* this host offset are counted.
|
868 |
*
|
869 |
* Note that guest_offset may not be cluster aligned. In this case, the
|
870 |
* returned *host_offset points to exact byte referenced by guest_offset and
|
871 |
* therefore isn't cluster aligned as well.
|
872 |
*
|
873 |
* Returns:
|
874 |
* 0: if no allocated clusters are available at the given offset.
|
875 |
* *bytes is normally unchanged. It is set to 0 if the cluster
|
876 |
* is allocated and doesn't need COW, but doesn't have the right
|
877 |
* physical offset.
|
878 |
*
|
879 |
* 1: if allocated clusters that don't require a COW are available at
|
880 |
* the requested offset. *bytes may have decreased and describes
|
881 |
* the length of the area that can be written to.
|
882 |
*
|
883 |
* -errno: in error cases
|
884 |
*/
|
885 |
static int handle_copied(BlockDriverState *bs, uint64_t guest_offset, |
886 |
uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m) |
887 |
{ |
888 |
BDRVQcowState *s = bs->opaque; |
889 |
int l2_index;
|
890 |
uint64_t cluster_offset; |
891 |
uint64_t *l2_table; |
892 |
unsigned int nb_clusters; |
893 |
unsigned int keep_clusters; |
894 |
int ret, pret;
|
895 |
|
896 |
trace_qcow2_handle_copied(qemu_coroutine_self(), guest_offset, *host_offset, |
897 |
*bytes); |
898 |
|
899 |
assert(*host_offset == 0 || offset_into_cluster(s, guest_offset)
|
900 |
== offset_into_cluster(s, *host_offset)); |
901 |
|
902 |
/*
|
903 |
* Calculate the number of clusters to look for. We stop at L2 table
|
904 |
* boundaries to keep things simple.
|
905 |
*/
|
906 |
nb_clusters = |
907 |
size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes); |
908 |
|
909 |
l2_index = offset_to_l2_index(s, guest_offset); |
910 |
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); |
911 |
|
912 |
/* Find L2 entry for the first involved cluster */
|
913 |
ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index); |
914 |
if (ret < 0) { |
915 |
return ret;
|
916 |
} |
917 |
|
918 |
cluster_offset = be64_to_cpu(l2_table[l2_index]); |
919 |
|
920 |
/* Check how many clusters are already allocated and don't need COW */
|
921 |
if (qcow2_get_cluster_type(cluster_offset) == QCOW2_CLUSTER_NORMAL
|
922 |
&& (cluster_offset & QCOW_OFLAG_COPIED)) |
923 |
{ |
924 |
/* If a specific host_offset is required, check it */
|
925 |
bool offset_matches =
|
926 |
(cluster_offset & L2E_OFFSET_MASK) == *host_offset; |
927 |
|
928 |
if (*host_offset != 0 && !offset_matches) { |
929 |
*bytes = 0;
|
930 |
ret = 0;
|
931 |
goto out;
|
932 |
} |
933 |
|
934 |
/* We keep all QCOW_OFLAG_COPIED clusters */
|
935 |
keep_clusters = |
936 |
count_contiguous_clusters(nb_clusters, s->cluster_size, |
937 |
&l2_table[l2_index], 0,
|
938 |
QCOW_OFLAG_COPIED | QCOW_OFLAG_ZERO); |
939 |
assert(keep_clusters <= nb_clusters); |
940 |
|
941 |
*bytes = MIN(*bytes, |
942 |
keep_clusters * s->cluster_size |
943 |
- offset_into_cluster(s, guest_offset)); |
944 |
|
945 |
ret = 1;
|
946 |
} else {
|
947 |
ret = 0;
|
948 |
} |
949 |
|
950 |
/* Cleanup */
|
951 |
out:
|
952 |
pret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
953 |
if (pret < 0) { |
954 |
return pret;
|
955 |
} |
956 |
|
957 |
/* Only return a host offset if we actually made progress. Otherwise we
|
958 |
* would make requirements for handle_alloc() that it can't fulfill */
|
959 |
if (ret) {
|
960 |
*host_offset = (cluster_offset & L2E_OFFSET_MASK) |
961 |
+ offset_into_cluster(s, guest_offset); |
962 |
} |
963 |
|
964 |
return ret;
|
965 |
} |
966 |
|
967 |
/*
|
968 |
* Allocates new clusters for the given guest_offset.
|
969 |
*
|
970 |
* At most *nb_clusters are allocated, and on return *nb_clusters is updated to
|
971 |
* contain the number of clusters that have been allocated and are contiguous
|
972 |
* in the image file.
|
973 |
*
|
974 |
* If *host_offset is non-zero, it specifies the offset in the image file at
|
975 |
* which the new clusters must start. *nb_clusters can be 0 on return in this
|
976 |
* case if the cluster at host_offset is already in use. If *host_offset is
|
977 |
* zero, the clusters can be allocated anywhere in the image file.
|
978 |
*
|
979 |
* *host_offset is updated to contain the offset into the image file at which
|
980 |
* the first allocated cluster starts.
|
981 |
*
|
982 |
* Return 0 on success and -errno in error cases. -EAGAIN means that the
|
983 |
* function has been waiting for another request and the allocation must be
|
984 |
* restarted, but the whole request should not be failed.
|
985 |
*/
|
986 |
static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset, |
987 |
uint64_t *host_offset, unsigned int *nb_clusters) |
988 |
{ |
989 |
BDRVQcowState *s = bs->opaque; |
990 |
|
991 |
trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset, |
992 |
*host_offset, *nb_clusters); |
993 |
|
994 |
/* Allocate new clusters */
|
995 |
trace_qcow2_cluster_alloc_phys(qemu_coroutine_self()); |
996 |
if (*host_offset == 0) { |
997 |
int64_t cluster_offset = |
998 |
qcow2_alloc_clusters(bs, *nb_clusters * s->cluster_size); |
999 |
if (cluster_offset < 0) { |
1000 |
return cluster_offset;
|
1001 |
} |
1002 |
*host_offset = cluster_offset; |
1003 |
return 0; |
1004 |
} else {
|
1005 |
int ret = qcow2_alloc_clusters_at(bs, *host_offset, *nb_clusters);
|
1006 |
if (ret < 0) { |
1007 |
return ret;
|
1008 |
} |
1009 |
*nb_clusters = ret; |
1010 |
return 0; |
1011 |
} |
1012 |
} |
1013 |
|
1014 |
/*
|
1015 |
* Allocates new clusters for an area that either is yet unallocated or needs a
|
1016 |
* copy on write. If *host_offset is non-zero, clusters are only allocated if
|
1017 |
* the new allocation can match the specified host offset.
|
1018 |
*
|
1019 |
* Note that guest_offset may not be cluster aligned. In this case, the
|
1020 |
* returned *host_offset points to exact byte referenced by guest_offset and
|
1021 |
* therefore isn't cluster aligned as well.
|
1022 |
*
|
1023 |
* Returns:
|
1024 |
* 0: if no clusters could be allocated. *bytes is set to 0,
|
1025 |
* *host_offset is left unchanged.
|
1026 |
*
|
1027 |
* 1: if new clusters were allocated. *bytes may be decreased if the
|
1028 |
* new allocation doesn't cover all of the requested area.
|
1029 |
* *host_offset is updated to contain the host offset of the first
|
1030 |
* newly allocated cluster.
|
1031 |
*
|
1032 |
* -errno: in error cases
|
1033 |
*/
|
1034 |
static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset, |
1035 |
uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m) |
1036 |
{ |
1037 |
BDRVQcowState *s = bs->opaque; |
1038 |
int l2_index;
|
1039 |
uint64_t *l2_table; |
1040 |
uint64_t entry; |
1041 |
unsigned int nb_clusters; |
1042 |
int ret;
|
1043 |
|
1044 |
uint64_t alloc_cluster_offset; |
1045 |
|
1046 |
trace_qcow2_handle_alloc(qemu_coroutine_self(), guest_offset, *host_offset, |
1047 |
*bytes); |
1048 |
assert(*bytes > 0);
|
1049 |
|
1050 |
/*
|
1051 |
* Calculate the number of clusters to look for. We stop at L2 table
|
1052 |
* boundaries to keep things simple.
|
1053 |
*/
|
1054 |
nb_clusters = |
1055 |
size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes); |
1056 |
|
1057 |
l2_index = offset_to_l2_index(s, guest_offset); |
1058 |
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); |
1059 |
|
1060 |
/* Find L2 entry for the first involved cluster */
|
1061 |
ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index); |
1062 |
if (ret < 0) { |
1063 |
return ret;
|
1064 |
} |
1065 |
|
1066 |
entry = be64_to_cpu(l2_table[l2_index]); |
1067 |
|
1068 |
/* For the moment, overwrite compressed clusters one by one */
|
1069 |
if (entry & QCOW_OFLAG_COMPRESSED) {
|
1070 |
nb_clusters = 1;
|
1071 |
} else {
|
1072 |
nb_clusters = count_cow_clusters(s, nb_clusters, l2_table, l2_index); |
1073 |
} |
1074 |
|
1075 |
/* This function is only called when there were no non-COW clusters, so if
|
1076 |
* we can't find any unallocated or COW clusters either, something is
|
1077 |
* wrong with our code. */
|
1078 |
assert(nb_clusters > 0);
|
1079 |
|
1080 |
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
1081 |
if (ret < 0) { |
1082 |
return ret;
|
1083 |
} |
1084 |
|
1085 |
/* Allocate, if necessary at a given offset in the image file */
|
1086 |
alloc_cluster_offset = start_of_cluster(s, *host_offset); |
1087 |
ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset, |
1088 |
&nb_clusters); |
1089 |
if (ret < 0) { |
1090 |
goto fail;
|
1091 |
} |
1092 |
|
1093 |
/* Can't extend contiguous allocation */
|
1094 |
if (nb_clusters == 0) { |
1095 |
*bytes = 0;
|
1096 |
return 0; |
1097 |
} |
1098 |
|
1099 |
/*
|
1100 |
* Save info needed for meta data update.
|
1101 |
*
|
1102 |
* requested_sectors: Number of sectors from the start of the first
|
1103 |
* newly allocated cluster to the end of the (possibly shortened
|
1104 |
* before) write request.
|
1105 |
*
|
1106 |
* avail_sectors: Number of sectors from the start of the first
|
1107 |
* newly allocated to the end of the last newly allocated cluster.
|
1108 |
*
|
1109 |
* nb_sectors: The number of sectors from the start of the first
|
1110 |
* newly allocated cluster to the end of the area that the write
|
1111 |
* request actually writes to (excluding COW at the end)
|
1112 |
*/
|
1113 |
int requested_sectors =
|
1114 |
(*bytes + offset_into_cluster(s, guest_offset)) |
1115 |
>> BDRV_SECTOR_BITS; |
1116 |
int avail_sectors = nb_clusters
|
1117 |
<< (s->cluster_bits - BDRV_SECTOR_BITS); |
1118 |
int alloc_n_start = offset_into_cluster(s, guest_offset)
|
1119 |
>> BDRV_SECTOR_BITS; |
1120 |
int nb_sectors = MIN(requested_sectors, avail_sectors);
|
1121 |
QCowL2Meta *old_m = *m; |
1122 |
|
1123 |
*m = g_malloc0(sizeof(**m));
|
1124 |
|
1125 |
**m = (QCowL2Meta) { |
1126 |
.next = old_m, |
1127 |
|
1128 |
.alloc_offset = alloc_cluster_offset, |
1129 |
.offset = start_of_cluster(s, guest_offset), |
1130 |
.nb_clusters = nb_clusters, |
1131 |
.nb_available = nb_sectors, |
1132 |
|
1133 |
.cow_start = { |
1134 |
.offset = 0,
|
1135 |
.nb_sectors = alloc_n_start, |
1136 |
}, |
1137 |
.cow_end = { |
1138 |
.offset = nb_sectors * BDRV_SECTOR_SIZE, |
1139 |
.nb_sectors = avail_sectors - nb_sectors, |
1140 |
}, |
1141 |
}; |
1142 |
qemu_co_queue_init(&(*m)->dependent_requests); |
1143 |
QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight); |
1144 |
|
1145 |
*host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset); |
1146 |
*bytes = MIN(*bytes, (nb_sectors * BDRV_SECTOR_SIZE) |
1147 |
- offset_into_cluster(s, guest_offset)); |
1148 |
assert(*bytes != 0);
|
1149 |
|
1150 |
return 1; |
1151 |
|
1152 |
fail:
|
1153 |
if (*m && (*m)->nb_clusters > 0) { |
1154 |
QLIST_REMOVE(*m, next_in_flight); |
1155 |
} |
1156 |
return ret;
|
1157 |
} |
1158 |
|
1159 |
/*
|
1160 |
* alloc_cluster_offset
|
1161 |
*
|
1162 |
* For a given offset on the virtual disk, find the cluster offset in qcow2
|
1163 |
* file. If the offset is not found, allocate a new cluster.
|
1164 |
*
|
1165 |
* If the cluster was already allocated, m->nb_clusters is set to 0 and
|
1166 |
* other fields in m are meaningless.
|
1167 |
*
|
1168 |
* If the cluster is newly allocated, m->nb_clusters is set to the number of
|
1169 |
* contiguous clusters that have been allocated. In this case, the other
|
1170 |
* fields of m are valid and contain information about the first allocated
|
1171 |
* cluster.
|
1172 |
*
|
1173 |
* If the request conflicts with another write request in flight, the coroutine
|
1174 |
* is queued and will be reentered when the dependency has completed.
|
1175 |
*
|
1176 |
* Return 0 on success and -errno in error cases
|
1177 |
*/
|
1178 |
int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
|
1179 |
int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m) |
1180 |
{ |
1181 |
BDRVQcowState *s = bs->opaque; |
1182 |
uint64_t start, remaining; |
1183 |
uint64_t cluster_offset; |
1184 |
uint64_t cur_bytes; |
1185 |
int ret;
|
1186 |
|
1187 |
trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset, |
1188 |
n_start, n_end); |
1189 |
|
1190 |
assert(n_start * BDRV_SECTOR_SIZE == offset_into_cluster(s, offset)); |
1191 |
offset = start_of_cluster(s, offset); |
1192 |
|
1193 |
again:
|
1194 |
start = offset + (n_start << BDRV_SECTOR_BITS); |
1195 |
remaining = (n_end - n_start) << BDRV_SECTOR_BITS; |
1196 |
cluster_offset = 0;
|
1197 |
*host_offset = 0;
|
1198 |
cur_bytes = 0;
|
1199 |
*m = NULL;
|
1200 |
|
1201 |
while (true) { |
1202 |
|
1203 |
if (!*host_offset) {
|
1204 |
*host_offset = start_of_cluster(s, cluster_offset); |
1205 |
} |
1206 |
|
1207 |
assert(remaining >= cur_bytes); |
1208 |
|
1209 |
start += cur_bytes; |
1210 |
remaining -= cur_bytes; |
1211 |
cluster_offset += cur_bytes; |
1212 |
|
1213 |
if (remaining == 0) { |
1214 |
break;
|
1215 |
} |
1216 |
|
1217 |
cur_bytes = remaining; |
1218 |
|
1219 |
/*
|
1220 |
* Now start gathering as many contiguous clusters as possible:
|
1221 |
*
|
1222 |
* 1. Check for overlaps with in-flight allocations
|
1223 |
*
|
1224 |
* a) Overlap not in the first cluster -> shorten this request and
|
1225 |
* let the caller handle the rest in its next loop iteration.
|
1226 |
*
|
1227 |
* b) Real overlaps of two requests. Yield and restart the search
|
1228 |
* for contiguous clusters (the situation could have changed
|
1229 |
* while we were sleeping)
|
1230 |
*
|
1231 |
* c) TODO: Request starts in the same cluster as the in-flight
|
1232 |
* allocation ends. Shorten the COW of the in-fight allocation,
|
1233 |
* set cluster_offset to write to the same cluster and set up
|
1234 |
* the right synchronisation between the in-flight request and
|
1235 |
* the new one.
|
1236 |
*/
|
1237 |
ret = handle_dependencies(bs, start, &cur_bytes, m); |
1238 |
if (ret == -EAGAIN) {
|
1239 |
/* Currently handle_dependencies() doesn't yield if we already had
|
1240 |
* an allocation. If it did, we would have to clean up the L2Meta
|
1241 |
* structs before starting over. */
|
1242 |
assert(*m == NULL);
|
1243 |
goto again;
|
1244 |
} else if (ret < 0) { |
1245 |
return ret;
|
1246 |
} else if (cur_bytes == 0) { |
1247 |
break;
|
1248 |
} else {
|
1249 |
/* handle_dependencies() may have decreased cur_bytes (shortened
|
1250 |
* the allocations below) so that the next dependency is processed
|
1251 |
* correctly during the next loop iteration. */
|
1252 |
} |
1253 |
|
1254 |
/*
|
1255 |
* 2. Count contiguous COPIED clusters.
|
1256 |
*/
|
1257 |
ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m); |
1258 |
if (ret < 0) { |
1259 |
return ret;
|
1260 |
} else if (ret) { |
1261 |
continue;
|
1262 |
} else if (cur_bytes == 0) { |
1263 |
break;
|
1264 |
} |
1265 |
|
1266 |
/*
|
1267 |
* 3. If the request still hasn't completed, allocate new clusters,
|
1268 |
* considering any cluster_offset of steps 1c or 2.
|
1269 |
*/
|
1270 |
ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m); |
1271 |
if (ret < 0) { |
1272 |
return ret;
|
1273 |
} else if (ret) { |
1274 |
continue;
|
1275 |
} else {
|
1276 |
assert(cur_bytes == 0);
|
1277 |
break;
|
1278 |
} |
1279 |
} |
1280 |
|
1281 |
*num = (n_end - n_start) - (remaining >> BDRV_SECTOR_BITS); |
1282 |
assert(*num > 0);
|
1283 |
assert(*host_offset != 0);
|
1284 |
|
1285 |
return 0; |
1286 |
} |
1287 |
|
1288 |
static int decompress_buffer(uint8_t *out_buf, int out_buf_size, |
1289 |
const uint8_t *buf, int buf_size) |
1290 |
{ |
1291 |
z_stream strm1, *strm = &strm1; |
1292 |
int ret, out_len;
|
1293 |
|
1294 |
memset(strm, 0, sizeof(*strm)); |
1295 |
|
1296 |
strm->next_in = (uint8_t *)buf; |
1297 |
strm->avail_in = buf_size; |
1298 |
strm->next_out = out_buf; |
1299 |
strm->avail_out = out_buf_size; |
1300 |
|
1301 |
ret = inflateInit2(strm, -12);
|
1302 |
if (ret != Z_OK)
|
1303 |
return -1; |
1304 |
ret = inflate(strm, Z_FINISH); |
1305 |
out_len = strm->next_out - out_buf; |
1306 |
if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
|
1307 |
out_len != out_buf_size) { |
1308 |
inflateEnd(strm); |
1309 |
return -1; |
1310 |
} |
1311 |
inflateEnd(strm); |
1312 |
return 0; |
1313 |
} |
1314 |
|
1315 |
int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
|
1316 |
{ |
1317 |
BDRVQcowState *s = bs->opaque; |
1318 |
int ret, csize, nb_csectors, sector_offset;
|
1319 |
uint64_t coffset; |
1320 |
|
1321 |
coffset = cluster_offset & s->cluster_offset_mask; |
1322 |
if (s->cluster_cache_offset != coffset) {
|
1323 |
nb_csectors = ((cluster_offset >> s->csize_shift) & s->csize_mask) + 1;
|
1324 |
sector_offset = coffset & 511;
|
1325 |
csize = nb_csectors * 512 - sector_offset;
|
1326 |
BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED); |
1327 |
ret = bdrv_read(bs->file, coffset >> 9, s->cluster_data, nb_csectors);
|
1328 |
if (ret < 0) { |
1329 |
return ret;
|
1330 |
} |
1331 |
if (decompress_buffer(s->cluster_cache, s->cluster_size,
|
1332 |
s->cluster_data + sector_offset, csize) < 0) {
|
1333 |
return -EIO;
|
1334 |
} |
1335 |
s->cluster_cache_offset = coffset; |
1336 |
} |
1337 |
return 0; |
1338 |
} |
1339 |
|
1340 |
/*
|
1341 |
* This discards as many clusters of nb_clusters as possible at once (i.e.
|
1342 |
* all clusters in the same L2 table) and returns the number of discarded
|
1343 |
* clusters.
|
1344 |
*/
|
1345 |
static int discard_single_l2(BlockDriverState *bs, uint64_t offset, |
1346 |
unsigned int nb_clusters, enum qcow2_discard_type type) |
1347 |
{ |
1348 |
BDRVQcowState *s = bs->opaque; |
1349 |
uint64_t *l2_table; |
1350 |
int l2_index;
|
1351 |
int ret;
|
1352 |
int i;
|
1353 |
|
1354 |
ret = get_cluster_table(bs, offset, &l2_table, &l2_index); |
1355 |
if (ret < 0) { |
1356 |
return ret;
|
1357 |
} |
1358 |
|
1359 |
/* Limit nb_clusters to one L2 table */
|
1360 |
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); |
1361 |
|
1362 |
for (i = 0; i < nb_clusters; i++) { |
1363 |
uint64_t old_offset; |
1364 |
|
1365 |
old_offset = be64_to_cpu(l2_table[l2_index + i]); |
1366 |
if ((old_offset & L2E_OFFSET_MASK) == 0) { |
1367 |
continue;
|
1368 |
} |
1369 |
|
1370 |
/* First remove L2 entries */
|
1371 |
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); |
1372 |
l2_table[l2_index + i] = cpu_to_be64(0);
|
1373 |
|
1374 |
/* Then decrease the refcount */
|
1375 |
qcow2_free_any_clusters(bs, old_offset, 1, type);
|
1376 |
} |
1377 |
|
1378 |
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
1379 |
if (ret < 0) { |
1380 |
return ret;
|
1381 |
} |
1382 |
|
1383 |
return nb_clusters;
|
1384 |
} |
1385 |
|
1386 |
int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
|
1387 |
int nb_sectors, enum qcow2_discard_type type) |
1388 |
{ |
1389 |
BDRVQcowState *s = bs->opaque; |
1390 |
uint64_t end_offset; |
1391 |
unsigned int nb_clusters; |
1392 |
int ret;
|
1393 |
|
1394 |
end_offset = offset + (nb_sectors << BDRV_SECTOR_BITS); |
1395 |
|
1396 |
/* Round start up and end down */
|
1397 |
offset = align_offset(offset, s->cluster_size); |
1398 |
end_offset &= ~(s->cluster_size - 1);
|
1399 |
|
1400 |
if (offset > end_offset) {
|
1401 |
return 0; |
1402 |
} |
1403 |
|
1404 |
nb_clusters = size_to_clusters(s, end_offset - offset); |
1405 |
|
1406 |
s->cache_discards = true;
|
1407 |
|
1408 |
/* Each L2 table is handled by its own loop iteration */
|
1409 |
while (nb_clusters > 0) { |
1410 |
ret = discard_single_l2(bs, offset, nb_clusters, type); |
1411 |
if (ret < 0) { |
1412 |
goto fail;
|
1413 |
} |
1414 |
|
1415 |
nb_clusters -= ret; |
1416 |
offset += (ret * s->cluster_size); |
1417 |
} |
1418 |
|
1419 |
ret = 0;
|
1420 |
fail:
|
1421 |
s->cache_discards = false;
|
1422 |
qcow2_process_discards(bs, ret); |
1423 |
|
1424 |
return ret;
|
1425 |
} |
1426 |
|
1427 |
/*
|
1428 |
* This zeroes as many clusters of nb_clusters as possible at once (i.e.
|
1429 |
* all clusters in the same L2 table) and returns the number of zeroed
|
1430 |
* clusters.
|
1431 |
*/
|
1432 |
static int zero_single_l2(BlockDriverState *bs, uint64_t offset, |
1433 |
unsigned int nb_clusters) |
1434 |
{ |
1435 |
BDRVQcowState *s = bs->opaque; |
1436 |
uint64_t *l2_table; |
1437 |
int l2_index;
|
1438 |
int ret;
|
1439 |
int i;
|
1440 |
|
1441 |
ret = get_cluster_table(bs, offset, &l2_table, &l2_index); |
1442 |
if (ret < 0) { |
1443 |
return ret;
|
1444 |
} |
1445 |
|
1446 |
/* Limit nb_clusters to one L2 table */
|
1447 |
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index); |
1448 |
|
1449 |
for (i = 0; i < nb_clusters; i++) { |
1450 |
uint64_t old_offset; |
1451 |
|
1452 |
old_offset = be64_to_cpu(l2_table[l2_index + i]); |
1453 |
|
1454 |
/* Update L2 entries */
|
1455 |
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); |
1456 |
if (old_offset & QCOW_OFLAG_COMPRESSED) {
|
1457 |
l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO); |
1458 |
qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
|
1459 |
} else {
|
1460 |
l2_table[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO); |
1461 |
} |
1462 |
} |
1463 |
|
1464 |
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
1465 |
if (ret < 0) { |
1466 |
return ret;
|
1467 |
} |
1468 |
|
1469 |
return nb_clusters;
|
1470 |
} |
1471 |
|
1472 |
int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors) |
1473 |
{ |
1474 |
BDRVQcowState *s = bs->opaque; |
1475 |
unsigned int nb_clusters; |
1476 |
int ret;
|
1477 |
|
1478 |
/* The zero flag is only supported by version 3 and newer */
|
1479 |
if (s->qcow_version < 3) { |
1480 |
return -ENOTSUP;
|
1481 |
} |
1482 |
|
1483 |
/* Each L2 table is handled by its own loop iteration */
|
1484 |
nb_clusters = size_to_clusters(s, nb_sectors << BDRV_SECTOR_BITS); |
1485 |
|
1486 |
s->cache_discards = true;
|
1487 |
|
1488 |
while (nb_clusters > 0) { |
1489 |
ret = zero_single_l2(bs, offset, nb_clusters); |
1490 |
if (ret < 0) { |
1491 |
goto fail;
|
1492 |
} |
1493 |
|
1494 |
nb_clusters -= ret; |
1495 |
offset += (ret * s->cluster_size); |
1496 |
} |
1497 |
|
1498 |
ret = 0;
|
1499 |
fail:
|
1500 |
s->cache_discards = false;
|
1501 |
qcow2_process_discards(bs, ret); |
1502 |
|
1503 |
return ret;
|
1504 |
} |
1505 |
|
1506 |
/*
|
1507 |
* Expands all zero clusters in a specific L1 table (or deallocates them, for
|
1508 |
* non-backed non-pre-allocated zero clusters).
|
1509 |
*
|
1510 |
* expanded_clusters is a bitmap where every bit corresponds to one cluster in
|
1511 |
* the image file; a bit gets set if the corresponding cluster has been used for
|
1512 |
* zero expansion (i.e., has been filled with zeroes and is referenced from an
|
1513 |
* L2 table). nb_clusters contains the total cluster count of the image file,
|
1514 |
* i.e., the number of bits in expanded_clusters.
|
1515 |
*/
|
1516 |
static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table, |
1517 |
int l1_size, uint8_t **expanded_clusters,
|
1518 |
uint64_t *nb_clusters) |
1519 |
{ |
1520 |
BDRVQcowState *s = bs->opaque; |
1521 |
bool is_active_l1 = (l1_table == s->l1_table);
|
1522 |
uint64_t *l2_table = NULL;
|
1523 |
int ret;
|
1524 |
int i, j;
|
1525 |
|
1526 |
if (!is_active_l1) {
|
1527 |
/* inactive L2 tables require a buffer to be stored in when loading
|
1528 |
* them from disk */
|
1529 |
l2_table = qemu_blockalign(bs, s->cluster_size); |
1530 |
} |
1531 |
|
1532 |
for (i = 0; i < l1_size; i++) { |
1533 |
uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK; |
1534 |
bool l2_dirty = false; |
1535 |
|
1536 |
if (!l2_offset) {
|
1537 |
/* unallocated */
|
1538 |
continue;
|
1539 |
} |
1540 |
|
1541 |
if (is_active_l1) {
|
1542 |
/* get active L2 tables from cache */
|
1543 |
ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, |
1544 |
(void **)&l2_table);
|
1545 |
} else {
|
1546 |
/* load inactive L2 tables from disk */
|
1547 |
ret = bdrv_read(bs->file, l2_offset / BDRV_SECTOR_SIZE, |
1548 |
(void *)l2_table, s->cluster_sectors);
|
1549 |
} |
1550 |
if (ret < 0) { |
1551 |
goto fail;
|
1552 |
} |
1553 |
|
1554 |
for (j = 0; j < s->l2_size; j++) { |
1555 |
uint64_t l2_entry = be64_to_cpu(l2_table[j]); |
1556 |
int64_t offset = l2_entry & L2E_OFFSET_MASK, cluster_index; |
1557 |
int cluster_type = qcow2_get_cluster_type(l2_entry);
|
1558 |
bool preallocated = offset != 0; |
1559 |
|
1560 |
if (cluster_type == QCOW2_CLUSTER_NORMAL) {
|
1561 |
cluster_index = offset >> s->cluster_bits; |
1562 |
assert((cluster_index >= 0) && (cluster_index < *nb_clusters));
|
1563 |
if ((*expanded_clusters)[cluster_index / 8] & |
1564 |
(1 << (cluster_index % 8))) { |
1565 |
/* Probably a shared L2 table; this cluster was a zero
|
1566 |
* cluster which has been expanded, its refcount
|
1567 |
* therefore most likely requires an update. */
|
1568 |
ret = qcow2_update_cluster_refcount(bs, cluster_index, 1,
|
1569 |
QCOW2_DISCARD_NEVER); |
1570 |
if (ret < 0) { |
1571 |
goto fail;
|
1572 |
} |
1573 |
/* Since we just increased the refcount, the COPIED flag may
|
1574 |
* no longer be set. */
|
1575 |
l2_table[j] = cpu_to_be64(l2_entry & ~QCOW_OFLAG_COPIED); |
1576 |
l2_dirty = true;
|
1577 |
} |
1578 |
continue;
|
1579 |
} |
1580 |
else if (qcow2_get_cluster_type(l2_entry) != QCOW2_CLUSTER_ZERO) { |
1581 |
continue;
|
1582 |
} |
1583 |
|
1584 |
if (!preallocated) {
|
1585 |
if (!bs->backing_hd) {
|
1586 |
/* not backed; therefore we can simply deallocate the
|
1587 |
* cluster */
|
1588 |
l2_table[j] = 0;
|
1589 |
l2_dirty = true;
|
1590 |
continue;
|
1591 |
} |
1592 |
|
1593 |
offset = qcow2_alloc_clusters(bs, s->cluster_size); |
1594 |
if (offset < 0) { |
1595 |
ret = offset; |
1596 |
goto fail;
|
1597 |
} |
1598 |
} |
1599 |
|
1600 |
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT, |
1601 |
offset, s->cluster_size); |
1602 |
if (ret < 0) { |
1603 |
if (!preallocated) {
|
1604 |
qcow2_free_clusters(bs, offset, s->cluster_size, |
1605 |
QCOW2_DISCARD_ALWAYS); |
1606 |
} |
1607 |
goto fail;
|
1608 |
} |
1609 |
|
1610 |
ret = bdrv_write_zeroes(bs->file, offset / BDRV_SECTOR_SIZE, |
1611 |
s->cluster_sectors); |
1612 |
if (ret < 0) { |
1613 |
if (!preallocated) {
|
1614 |
qcow2_free_clusters(bs, offset, s->cluster_size, |
1615 |
QCOW2_DISCARD_ALWAYS); |
1616 |
} |
1617 |
goto fail;
|
1618 |
} |
1619 |
|
1620 |
l2_table[j] = cpu_to_be64(offset | QCOW_OFLAG_COPIED); |
1621 |
l2_dirty = true;
|
1622 |
|
1623 |
cluster_index = offset >> s->cluster_bits; |
1624 |
|
1625 |
if (cluster_index >= *nb_clusters) {
|
1626 |
uint64_t old_bitmap_size = (*nb_clusters + 7) / 8; |
1627 |
uint64_t new_bitmap_size; |
1628 |
/* The offset may lie beyond the old end of the underlying image
|
1629 |
* file for growable files only */
|
1630 |
assert(bs->file->growable); |
1631 |
*nb_clusters = size_to_clusters(s, bs->file->total_sectors * |
1632 |
BDRV_SECTOR_SIZE); |
1633 |
new_bitmap_size = (*nb_clusters + 7) / 8; |
1634 |
*expanded_clusters = g_realloc(*expanded_clusters, |
1635 |
new_bitmap_size); |
1636 |
/* clear the newly allocated space */
|
1637 |
memset(&(*expanded_clusters)[old_bitmap_size], 0,
|
1638 |
new_bitmap_size - old_bitmap_size); |
1639 |
} |
1640 |
|
1641 |
assert((cluster_index >= 0) && (cluster_index < *nb_clusters));
|
1642 |
(*expanded_clusters)[cluster_index / 8] |= 1 << (cluster_index % 8); |
1643 |
} |
1644 |
|
1645 |
if (is_active_l1) {
|
1646 |
if (l2_dirty) {
|
1647 |
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table); |
1648 |
qcow2_cache_depends_on_flush(s->l2_table_cache); |
1649 |
} |
1650 |
ret = qcow2_cache_put(bs, s->l2_table_cache, (void **)&l2_table);
|
1651 |
if (ret < 0) { |
1652 |
l2_table = NULL;
|
1653 |
goto fail;
|
1654 |
} |
1655 |
} else {
|
1656 |
if (l2_dirty) {
|
1657 |
ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT & |
1658 |
~(QCOW2_OL_INACTIVE_L2 | QCOW2_OL_ACTIVE_L2), l2_offset, |
1659 |
s->cluster_size); |
1660 |
if (ret < 0) { |
1661 |
goto fail;
|
1662 |
} |
1663 |
|
1664 |
ret = bdrv_write(bs->file, l2_offset / BDRV_SECTOR_SIZE, |
1665 |
(void *)l2_table, s->cluster_sectors);
|
1666 |
if (ret < 0) { |
1667 |
goto fail;
|
1668 |
} |
1669 |
} |
1670 |
} |
1671 |
} |
1672 |
|
1673 |
ret = 0;
|
1674 |
|
1675 |
fail:
|
1676 |
if (l2_table) {
|
1677 |
if (!is_active_l1) {
|
1678 |
qemu_vfree(l2_table); |
1679 |
} else {
|
1680 |
if (ret < 0) { |
1681 |
qcow2_cache_put(bs, s->l2_table_cache, (void **)&l2_table);
|
1682 |
} else {
|
1683 |
ret = qcow2_cache_put(bs, s->l2_table_cache, |
1684 |
(void **)&l2_table);
|
1685 |
} |
1686 |
} |
1687 |
} |
1688 |
return ret;
|
1689 |
} |
1690 |
|
1691 |
/*
|
1692 |
* For backed images, expands all zero clusters on the image. For non-backed
|
1693 |
* images, deallocates all non-pre-allocated zero clusters (and claims the
|
1694 |
* allocation for pre-allocated ones). This is important for downgrading to a
|
1695 |
* qcow2 version which doesn't yet support metadata zero clusters.
|
1696 |
*/
|
1697 |
int qcow2_expand_zero_clusters(BlockDriverState *bs)
|
1698 |
{ |
1699 |
BDRVQcowState *s = bs->opaque; |
1700 |
uint64_t *l1_table = NULL;
|
1701 |
uint64_t nb_clusters; |
1702 |
uint8_t *expanded_clusters; |
1703 |
int ret;
|
1704 |
int i, j;
|
1705 |
|
1706 |
nb_clusters = size_to_clusters(s, bs->file->total_sectors * |
1707 |
BDRV_SECTOR_SIZE); |
1708 |
expanded_clusters = g_malloc0((nb_clusters + 7) / 8); |
1709 |
|
1710 |
ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size, |
1711 |
&expanded_clusters, &nb_clusters); |
1712 |
if (ret < 0) { |
1713 |
goto fail;
|
1714 |
} |
1715 |
|
1716 |
/* Inactive L1 tables may point to active L2 tables - therefore it is
|
1717 |
* necessary to flush the L2 table cache before trying to access the L2
|
1718 |
* tables pointed to by inactive L1 entries (else we might try to expand
|
1719 |
* zero clusters that have already been expanded); furthermore, it is also
|
1720 |
* necessary to empty the L2 table cache, since it may contain tables which
|
1721 |
* are now going to be modified directly on disk, bypassing the cache.
|
1722 |
* qcow2_cache_empty() does both for us. */
|
1723 |
ret = qcow2_cache_empty(bs, s->l2_table_cache); |
1724 |
if (ret < 0) { |
1725 |
goto fail;
|
1726 |
} |
1727 |
|
1728 |
for (i = 0; i < s->nb_snapshots; i++) { |
1729 |
int l1_sectors = (s->snapshots[i].l1_size * sizeof(uint64_t) + |
1730 |
BDRV_SECTOR_SIZE - 1) / BDRV_SECTOR_SIZE;
|
1731 |
|
1732 |
l1_table = g_realloc(l1_table, l1_sectors * BDRV_SECTOR_SIZE); |
1733 |
|
1734 |
ret = bdrv_read(bs->file, s->snapshots[i].l1_table_offset / |
1735 |
BDRV_SECTOR_SIZE, (void *)l1_table, l1_sectors);
|
1736 |
if (ret < 0) { |
1737 |
goto fail;
|
1738 |
} |
1739 |
|
1740 |
for (j = 0; j < s->snapshots[i].l1_size; j++) { |
1741 |
be64_to_cpus(&l1_table[j]); |
1742 |
} |
1743 |
|
1744 |
ret = expand_zero_clusters_in_l1(bs, l1_table, s->snapshots[i].l1_size, |
1745 |
&expanded_clusters, &nb_clusters); |
1746 |
if (ret < 0) { |
1747 |
goto fail;
|
1748 |
} |
1749 |
} |
1750 |
|
1751 |
ret = 0;
|
1752 |
|
1753 |
fail:
|
1754 |
g_free(expanded_clusters); |
1755 |
g_free(l1_table); |
1756 |
return ret;
|
1757 |
} |