2516 lines
86 KiB
C
2516 lines
86 KiB
C
/*
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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/osdep.h"
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#include <zlib.h>
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#include "qapi/error.h"
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#include "qcow2.h"
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#include "qemu/bswap.h"
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#include "qemu/memalign.h"
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#include "trace.h"
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int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t exact_size)
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{
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BDRVQcow2State *s = bs->opaque;
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int new_l1_size, i, ret;
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if (exact_size >= s->l1_size) {
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return 0;
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}
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new_l1_size = exact_size;
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#ifdef DEBUG_ALLOC2
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fprintf(stderr, "shrink l1_table from %d to %d\n", s->l1_size, new_l1_size);
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#endif
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BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_WRITE_TABLE);
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ret = bdrv_pwrite_zeroes(bs->file, s->l1_table_offset +
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new_l1_size * L1E_SIZE,
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(s->l1_size - new_l1_size) * L1E_SIZE, 0);
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if (ret < 0) {
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goto fail;
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}
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ret = bdrv_flush(bs->file->bs);
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if (ret < 0) {
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goto fail;
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}
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BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_FREE_L2_CLUSTERS);
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for (i = s->l1_size - 1; i > new_l1_size - 1; i--) {
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if ((s->l1_table[i] & L1E_OFFSET_MASK) == 0) {
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continue;
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}
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qcow2_free_clusters(bs, s->l1_table[i] & L1E_OFFSET_MASK,
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s->cluster_size, QCOW2_DISCARD_ALWAYS);
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s->l1_table[i] = 0;
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}
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return 0;
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fail:
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/*
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* If the write in the l1_table failed the image may contain a partially
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* overwritten l1_table. In this case it would be better to clear the
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* l1_table in memory to avoid possible image corruption.
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*/
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memset(s->l1_table + new_l1_size, 0,
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(s->l1_size - new_l1_size) * L1E_SIZE);
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return ret;
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}
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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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BDRVQcow2State *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 old_l1_table_offset, old_l1_size;
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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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if (min_size <= s->l1_size)
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return 0;
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/* Do a sanity check on min_size before trying to calculate new_l1_size
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* (this prevents overflows during the while loop for the calculation of
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* new_l1_size) */
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if (min_size > INT_MAX / L1E_SIZE) {
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return -EFBIG;
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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 = DIV_ROUND_UP(new_l1_size * 3, 2);
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}
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}
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QEMU_BUILD_BUG_ON(QCOW_MAX_L1_SIZE > INT_MAX);
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if (new_l1_size > QCOW_MAX_L1_SIZE / L1E_SIZE) {
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return -EFBIG;
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}
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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 = L1E_SIZE * new_l1_size;
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new_l1_table = qemu_try_blockalign(bs->file->bs, new_l1_size2);
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if (new_l1_table == NULL) {
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return -ENOMEM;
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}
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memset(new_l1_table, 0, new_l1_size2);
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if (s->l1_size) {
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memcpy(new_l1_table, s->l1_table, s->l1_size * L1E_SIZE);
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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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qemu_vfree(new_l1_table);
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return new_l1_table_offset;
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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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/* 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, 0, new_l1_table_offset,
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new_l1_size2, false);
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if (ret < 0) {
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goto fail;
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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_size2,
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new_l1_table, 0);
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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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/* set new table */
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BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ACTIVATE_TABLE);
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stl_be_p(data, new_l1_size);
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stq_be_p(data + 4, new_l1_table_offset);
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ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_size),
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sizeof(data), data, 0);
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if (ret < 0) {
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goto fail;
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}
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qemu_vfree(s->l1_table);
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old_l1_table_offset = s->l1_table_offset;
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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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old_l1_size = s->l1_size;
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s->l1_size = new_l1_size;
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qcow2_free_clusters(bs, old_l1_table_offset, old_l1_size * L1E_SIZE,
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QCOW2_DISCARD_OTHER);
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return 0;
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fail:
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qemu_vfree(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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* l2_load
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*
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* @bs: The BlockDriverState
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* @offset: A guest offset, used to calculate what slice of the L2
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* table to load.
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* @l2_offset: Offset to the L2 table in the image file.
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* @l2_slice: Location to store the pointer to the L2 slice.
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*
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* Loads a L2 slice into memory (L2 slices are the parts of L2 tables
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* that are loaded by the qcow2 cache). If the slice is in the cache,
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* the cache is used; otherwise the L2 slice is loaded from the image
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* file.
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*/
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static int l2_load(BlockDriverState *bs, uint64_t offset,
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uint64_t l2_offset, uint64_t **l2_slice)
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{
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BDRVQcow2State *s = bs->opaque;
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int start_of_slice = l2_entry_size(s) *
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(offset_to_l2_index(s, offset) - offset_to_l2_slice_index(s, offset));
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return qcow2_cache_get(bs, s->l2_table_cache, l2_offset + start_of_slice,
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(void **)l2_slice);
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}
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/*
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* Writes an L1 entry to disk (note that depending on the alignment
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* requirements this function may write more that just one entry in
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* order to prevent bdrv_pwrite from performing a read-modify-write)
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*/
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int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index)
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{
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BDRVQcow2State *s = bs->opaque;
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int l1_start_index;
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int i, ret;
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int bufsize = MAX(L1E_SIZE,
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MIN(bs->file->bs->bl.request_alignment, s->cluster_size));
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int nentries = bufsize / L1E_SIZE;
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g_autofree uint64_t *buf = g_try_new0(uint64_t, nentries);
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if (buf == NULL) {
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return -ENOMEM;
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}
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l1_start_index = QEMU_ALIGN_DOWN(l1_index, nentries);
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for (i = 0; i < MIN(nentries, s->l1_size - l1_start_index); i++) {
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buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]);
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}
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ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1,
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s->l1_table_offset + L1E_SIZE * l1_start_index, bufsize, false);
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if (ret < 0) {
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return ret;
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}
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BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
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ret = bdrv_pwrite_sync(bs->file,
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s->l1_table_offset + L1E_SIZE * l1_start_index,
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bufsize, buf, 0);
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if (ret < 0) {
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return ret;
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}
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return 0;
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}
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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)
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{
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BDRVQcow2State *s = bs->opaque;
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uint64_t old_l2_offset;
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uint64_t *l2_slice = NULL;
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unsigned slice, slice_size2, n_slices;
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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];
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trace_qcow2_l2_allocate(bs, l1_index);
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/* allocate a new l2 entry */
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l2_offset = qcow2_alloc_clusters(bs, s->l2_size * l2_entry_size(s));
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if (l2_offset < 0) {
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ret = l2_offset;
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goto fail;
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}
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/* The offset must fit in the offset field of the L1 table entry */
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assert((l2_offset & L1E_OFFSET_MASK) == l2_offset);
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/* If we're allocating the table at offset 0 then something is wrong */
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if (l2_offset == 0) {
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qcow2_signal_corruption(bs, true, -1, -1, "Preventing invalid "
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"allocation of L2 table at offset 0");
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ret = -EIO;
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goto fail;
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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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/* allocate a new entry in the l2 cache */
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slice_size2 = s->l2_slice_size * l2_entry_size(s);
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n_slices = s->cluster_size / slice_size2;
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trace_qcow2_l2_allocate_get_empty(bs, l1_index);
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for (slice = 0; slice < n_slices; slice++) {
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ret = qcow2_cache_get_empty(bs, s->l2_table_cache,
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l2_offset + slice * slice_size2,
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(void **) &l2_slice);
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if (ret < 0) {
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goto fail;
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}
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if ((old_l2_offset & L1E_OFFSET_MASK) == 0) {
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/* if there was no old l2 table, clear the new slice */
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memset(l2_slice, 0, slice_size2);
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} else {
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uint64_t *old_slice;
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uint64_t old_l2_slice_offset =
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(old_l2_offset & L1E_OFFSET_MASK) + slice * slice_size2;
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/* if there was an old l2 table, read a slice from the disk */
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BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ);
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ret = qcow2_cache_get(bs, s->l2_table_cache, old_l2_slice_offset,
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(void **) &old_slice);
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if (ret < 0) {
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goto fail;
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}
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memcpy(l2_slice, old_slice, slice_size2);
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qcow2_cache_put(s->l2_table_cache, (void **) &old_slice);
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}
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/* write the l2 slice to the file */
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BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE);
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trace_qcow2_l2_allocate_write_l2(bs, l1_index);
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qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
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qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
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}
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ret = qcow2_cache_flush(bs, s->l2_table_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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/* update the L1 entry */
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trace_qcow2_l2_allocate_write_l1(bs, l1_index);
|
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s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED;
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ret = qcow2_write_l1_entry(bs, l1_index);
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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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trace_qcow2_l2_allocate_done(bs, l1_index, 0);
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return 0;
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fail:
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|
trace_qcow2_l2_allocate_done(bs, l1_index, ret);
|
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if (l2_slice != NULL) {
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
}
|
|
s->l1_table[l1_index] = old_l2_offset;
|
|
if (l2_offset > 0) {
|
|
qcow2_free_clusters(bs, l2_offset, s->l2_size * l2_entry_size(s),
|
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QCOW2_DISCARD_ALWAYS);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* For a given L2 entry, count the number of contiguous subclusters of
|
|
* the same type starting from @sc_from. Compressed clusters are
|
|
* treated as if they were divided into subclusters of size
|
|
* s->subcluster_size.
|
|
*
|
|
* Return the number of contiguous subclusters and set @type to the
|
|
* subcluster type.
|
|
*
|
|
* If the L2 entry is invalid return -errno and set @type to
|
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* QCOW2_SUBCLUSTER_INVALID.
|
|
*/
|
|
static int qcow2_get_subcluster_range_type(BlockDriverState *bs,
|
|
uint64_t l2_entry,
|
|
uint64_t l2_bitmap,
|
|
unsigned sc_from,
|
|
QCow2SubclusterType *type)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
uint32_t val;
|
|
|
|
*type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_from);
|
|
|
|
if (*type == QCOW2_SUBCLUSTER_INVALID) {
|
|
return -EINVAL;
|
|
} else if (!has_subclusters(s) || *type == QCOW2_SUBCLUSTER_COMPRESSED) {
|
|
return s->subclusters_per_cluster - sc_from;
|
|
}
|
|
|
|
switch (*type) {
|
|
case QCOW2_SUBCLUSTER_NORMAL:
|
|
val = l2_bitmap | QCOW_OFLAG_SUB_ALLOC_RANGE(0, sc_from);
|
|
return cto32(val) - sc_from;
|
|
|
|
case QCOW2_SUBCLUSTER_ZERO_PLAIN:
|
|
case QCOW2_SUBCLUSTER_ZERO_ALLOC:
|
|
val = (l2_bitmap | QCOW_OFLAG_SUB_ZERO_RANGE(0, sc_from)) >> 32;
|
|
return cto32(val) - sc_from;
|
|
|
|
case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
|
|
case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
|
|
val = ((l2_bitmap >> 32) | l2_bitmap)
|
|
& ~QCOW_OFLAG_SUB_ALLOC_RANGE(0, sc_from);
|
|
return ctz32(val) - sc_from;
|
|
|
|
default:
|
|
g_assert_not_reached();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Return the number of contiguous subclusters of the exact same type
|
|
* in a given L2 slice, starting from cluster @l2_index, subcluster
|
|
* @sc_index. Allocated subclusters are required to be contiguous in
|
|
* the image file.
|
|
* At most @nb_clusters are checked (note that this means clusters,
|
|
* not subclusters).
|
|
* Compressed clusters are always processed one by one but for the
|
|
* purpose of this count they are treated as if they were divided into
|
|
* subclusters of size s->subcluster_size.
|
|
* On failure return -errno and update @l2_index to point to the
|
|
* invalid entry.
|
|
*/
|
|
static int count_contiguous_subclusters(BlockDriverState *bs, int nb_clusters,
|
|
unsigned sc_index, uint64_t *l2_slice,
|
|
unsigned *l2_index)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
int i, count = 0;
|
|
bool check_offset = false;
|
|
uint64_t expected_offset = 0;
|
|
QCow2SubclusterType expected_type = QCOW2_SUBCLUSTER_NORMAL, type;
|
|
|
|
assert(*l2_index + nb_clusters <= s->l2_slice_size);
|
|
|
|
for (i = 0; i < nb_clusters; i++) {
|
|
unsigned first_sc = (i == 0) ? sc_index : 0;
|
|
uint64_t l2_entry = get_l2_entry(s, l2_slice, *l2_index + i);
|
|
uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, *l2_index + i);
|
|
int ret = qcow2_get_subcluster_range_type(bs, l2_entry, l2_bitmap,
|
|
first_sc, &type);
|
|
if (ret < 0) {
|
|
*l2_index += i; /* Point to the invalid entry */
|
|
return -EIO;
|
|
}
|
|
if (i == 0) {
|
|
if (type == QCOW2_SUBCLUSTER_COMPRESSED) {
|
|
/* Compressed clusters are always processed one by one */
|
|
return ret;
|
|
}
|
|
expected_type = type;
|
|
expected_offset = l2_entry & L2E_OFFSET_MASK;
|
|
check_offset = (type == QCOW2_SUBCLUSTER_NORMAL ||
|
|
type == QCOW2_SUBCLUSTER_ZERO_ALLOC ||
|
|
type == QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC);
|
|
} else if (type != expected_type) {
|
|
break;
|
|
} else if (check_offset) {
|
|
expected_offset += s->cluster_size;
|
|
if (expected_offset != (l2_entry & L2E_OFFSET_MASK)) {
|
|
break;
|
|
}
|
|
}
|
|
count += ret;
|
|
/* Stop if there are type changes before the end of the cluster */
|
|
if (first_sc + ret < s->subclusters_per_cluster) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
return count;
|
|
}
|
|
|
|
static int coroutine_fn do_perform_cow_read(BlockDriverState *bs,
|
|
uint64_t src_cluster_offset,
|
|
unsigned offset_in_cluster,
|
|
QEMUIOVector *qiov)
|
|
{
|
|
int ret;
|
|
|
|
if (qiov->size == 0) {
|
|
return 0;
|
|
}
|
|
|
|
BLKDBG_EVENT(bs->file, BLKDBG_COW_READ);
|
|
|
|
if (!bs->drv) {
|
|
return -ENOMEDIUM;
|
|
}
|
|
|
|
/*
|
|
* We never deal with requests that don't satisfy
|
|
* bdrv_check_qiov_request(), and aligning requests to clusters never
|
|
* breaks this condition. So, do some assertions before calling
|
|
* bs->drv->bdrv_co_preadv_part() which has int64_t arguments.
|
|
*/
|
|
assert(src_cluster_offset <= INT64_MAX);
|
|
assert(src_cluster_offset + offset_in_cluster <= INT64_MAX);
|
|
/* Cast qiov->size to uint64_t to silence a compiler warning on -m32 */
|
|
assert((uint64_t)qiov->size <= INT64_MAX);
|
|
bdrv_check_qiov_request(src_cluster_offset + offset_in_cluster, qiov->size,
|
|
qiov, 0, &error_abort);
|
|
/*
|
|
* Call .bdrv_co_readv() directly instead of using the public block-layer
|
|
* interface. This avoids double I/O throttling and request tracking,
|
|
* which can lead to deadlock when block layer copy-on-read is enabled.
|
|
*/
|
|
ret = bs->drv->bdrv_co_preadv_part(bs,
|
|
src_cluster_offset + offset_in_cluster,
|
|
qiov->size, qiov, 0, 0);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int coroutine_fn do_perform_cow_write(BlockDriverState *bs,
|
|
uint64_t cluster_offset,
|
|
unsigned offset_in_cluster,
|
|
QEMUIOVector *qiov)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
int ret;
|
|
|
|
if (qiov->size == 0) {
|
|
return 0;
|
|
}
|
|
|
|
ret = qcow2_pre_write_overlap_check(bs, 0,
|
|
cluster_offset + offset_in_cluster, qiov->size, true);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE);
|
|
ret = bdrv_co_pwritev(s->data_file, cluster_offset + offset_in_cluster,
|
|
qiov->size, qiov, 0);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
/*
|
|
* get_host_offset
|
|
*
|
|
* For a given offset of the virtual disk find the equivalent host
|
|
* offset in the qcow2 file and store it in *host_offset. Neither
|
|
* offset needs to be aligned to a cluster boundary.
|
|
*
|
|
* If the cluster is unallocated then *host_offset will be 0.
|
|
* If the cluster is compressed then *host_offset will contain the l2 entry.
|
|
*
|
|
* On entry, *bytes is the maximum number of contiguous bytes starting at
|
|
* offset that we are interested in.
|
|
*
|
|
* On exit, *bytes is the number of bytes starting at offset that have the same
|
|
* subcluster type and (if applicable) are stored contiguously in the image
|
|
* file. The subcluster type is stored in *subcluster_type.
|
|
* Compressed clusters are always processed one by one.
|
|
*
|
|
* Returns 0 on success, -errno in error cases.
|
|
*/
|
|
int qcow2_get_host_offset(BlockDriverState *bs, uint64_t offset,
|
|
unsigned int *bytes, uint64_t *host_offset,
|
|
QCow2SubclusterType *subcluster_type)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
unsigned int l2_index, sc_index;
|
|
uint64_t l1_index, l2_offset, *l2_slice, l2_entry, l2_bitmap;
|
|
int sc;
|
|
unsigned int offset_in_cluster;
|
|
uint64_t bytes_available, bytes_needed, nb_clusters;
|
|
QCow2SubclusterType type;
|
|
int ret;
|
|
|
|
offset_in_cluster = offset_into_cluster(s, offset);
|
|
bytes_needed = (uint64_t) *bytes + offset_in_cluster;
|
|
|
|
/* compute how many bytes there are between the start of the cluster
|
|
* containing offset and the end of the l2 slice that contains
|
|
* the entry pointing to it */
|
|
bytes_available =
|
|
((uint64_t) (s->l2_slice_size - offset_to_l2_slice_index(s, offset)))
|
|
<< s->cluster_bits;
|
|
|
|
if (bytes_needed > bytes_available) {
|
|
bytes_needed = bytes_available;
|
|
}
|
|
|
|
*host_offset = 0;
|
|
|
|
/* seek to the l2 offset in the l1 table */
|
|
|
|
l1_index = offset_to_l1_index(s, offset);
|
|
if (l1_index >= s->l1_size) {
|
|
type = QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN;
|
|
goto out;
|
|
}
|
|
|
|
l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
|
|
if (!l2_offset) {
|
|
type = QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN;
|
|
goto out;
|
|
}
|
|
|
|
if (offset_into_cluster(s, l2_offset)) {
|
|
qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64
|
|
" unaligned (L1 index: %#" PRIx64 ")",
|
|
l2_offset, l1_index);
|
|
return -EIO;
|
|
}
|
|
|
|
/* load the l2 slice in memory */
|
|
|
|
ret = l2_load(bs, offset, l2_offset, &l2_slice);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
/* find the cluster offset for the given disk offset */
|
|
|
|
l2_index = offset_to_l2_slice_index(s, offset);
|
|
sc_index = offset_to_sc_index(s, offset);
|
|
l2_entry = get_l2_entry(s, l2_slice, l2_index);
|
|
l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index);
|
|
|
|
nb_clusters = size_to_clusters(s, bytes_needed);
|
|
/* bytes_needed <= *bytes + offset_in_cluster, both of which are unsigned
|
|
* integers; the minimum cluster size is 512, so this assertion is always
|
|
* true */
|
|
assert(nb_clusters <= INT_MAX);
|
|
|
|
type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index);
|
|
if (s->qcow_version < 3 && (type == QCOW2_SUBCLUSTER_ZERO_PLAIN ||
|
|
type == QCOW2_SUBCLUSTER_ZERO_ALLOC)) {
|
|
qcow2_signal_corruption(bs, true, -1, -1, "Zero cluster entry found"
|
|
" in pre-v3 image (L2 offset: %#" PRIx64
|
|
", L2 index: %#x)", l2_offset, l2_index);
|
|
ret = -EIO;
|
|
goto fail;
|
|
}
|
|
switch (type) {
|
|
case QCOW2_SUBCLUSTER_INVALID:
|
|
break; /* This is handled by count_contiguous_subclusters() below */
|
|
case QCOW2_SUBCLUSTER_COMPRESSED:
|
|
if (has_data_file(bs)) {
|
|
qcow2_signal_corruption(bs, true, -1, -1, "Compressed cluster "
|
|
"entry found in image with external data "
|
|
"file (L2 offset: %#" PRIx64 ", L2 index: "
|
|
"%#x)", l2_offset, l2_index);
|
|
ret = -EIO;
|
|
goto fail;
|
|
}
|
|
*host_offset = l2_entry;
|
|
break;
|
|
case QCOW2_SUBCLUSTER_ZERO_PLAIN:
|
|
case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
|
|
break;
|
|
case QCOW2_SUBCLUSTER_ZERO_ALLOC:
|
|
case QCOW2_SUBCLUSTER_NORMAL:
|
|
case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC: {
|
|
uint64_t host_cluster_offset = l2_entry & L2E_OFFSET_MASK;
|
|
*host_offset = host_cluster_offset + offset_in_cluster;
|
|
if (offset_into_cluster(s, host_cluster_offset)) {
|
|
qcow2_signal_corruption(bs, true, -1, -1,
|
|
"Cluster allocation offset %#"
|
|
PRIx64 " unaligned (L2 offset: %#" PRIx64
|
|
", L2 index: %#x)", host_cluster_offset,
|
|
l2_offset, l2_index);
|
|
ret = -EIO;
|
|
goto fail;
|
|
}
|
|
if (has_data_file(bs) && *host_offset != offset) {
|
|
qcow2_signal_corruption(bs, true, -1, -1,
|
|
"External data file host cluster offset %#"
|
|
PRIx64 " does not match guest cluster "
|
|
"offset: %#" PRIx64
|
|
", L2 index: %#x)", host_cluster_offset,
|
|
offset - offset_in_cluster, l2_index);
|
|
ret = -EIO;
|
|
goto fail;
|
|
}
|
|
break;
|
|
}
|
|
default:
|
|
abort();
|
|
}
|
|
|
|
sc = count_contiguous_subclusters(bs, nb_clusters, sc_index,
|
|
l2_slice, &l2_index);
|
|
if (sc < 0) {
|
|
qcow2_signal_corruption(bs, true, -1, -1, "Invalid cluster entry found "
|
|
" (L2 offset: %#" PRIx64 ", L2 index: %#x)",
|
|
l2_offset, l2_index);
|
|
ret = -EIO;
|
|
goto fail;
|
|
}
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
|
|
bytes_available = ((int64_t)sc + sc_index) << s->subcluster_bits;
|
|
|
|
out:
|
|
if (bytes_available > bytes_needed) {
|
|
bytes_available = bytes_needed;
|
|
}
|
|
|
|
/* bytes_available <= bytes_needed <= *bytes + offset_in_cluster;
|
|
* subtracting offset_in_cluster will therefore definitely yield something
|
|
* not exceeding UINT_MAX */
|
|
assert(bytes_available - offset_in_cluster <= UINT_MAX);
|
|
*bytes = bytes_available - offset_in_cluster;
|
|
|
|
*subcluster_type = type;
|
|
|
|
return 0;
|
|
|
|
fail:
|
|
qcow2_cache_put(s->l2_table_cache, (void **)&l2_slice);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* get_cluster_table
|
|
*
|
|
* for a given disk offset, load (and allocate if needed)
|
|
* the appropriate slice of its l2 table.
|
|
*
|
|
* the cluster index in the l2 slice is given to the caller.
|
|
*
|
|
* Returns 0 on success, -errno in failure case
|
|
*/
|
|
static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
|
|
uint64_t **new_l2_slice,
|
|
int *new_l2_index)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
unsigned int l2_index;
|
|
uint64_t l1_index, l2_offset;
|
|
uint64_t *l2_slice = NULL;
|
|
int ret;
|
|
|
|
/* seek to the l2 offset in the l1 table */
|
|
|
|
l1_index = offset_to_l1_index(s, offset);
|
|
if (l1_index >= s->l1_size) {
|
|
ret = qcow2_grow_l1_table(bs, l1_index + 1, false);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
assert(l1_index < s->l1_size);
|
|
l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
|
|
if (offset_into_cluster(s, l2_offset)) {
|
|
qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64
|
|
" unaligned (L1 index: %#" PRIx64 ")",
|
|
l2_offset, l1_index);
|
|
return -EIO;
|
|
}
|
|
|
|
if (!(s->l1_table[l1_index] & QCOW_OFLAG_COPIED)) {
|
|
/* First allocate a new L2 table (and do COW if needed) */
|
|
ret = l2_allocate(bs, l1_index);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
/* Then decrease the refcount of the old table */
|
|
if (l2_offset) {
|
|
qcow2_free_clusters(bs, l2_offset, s->l2_size * l2_entry_size(s),
|
|
QCOW2_DISCARD_OTHER);
|
|
}
|
|
|
|
/* Get the offset of the newly-allocated l2 table */
|
|
l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
|
|
assert(offset_into_cluster(s, l2_offset) == 0);
|
|
}
|
|
|
|
/* load the l2 slice in memory */
|
|
ret = l2_load(bs, offset, l2_offset, &l2_slice);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
/* find the cluster offset for the given disk offset */
|
|
|
|
l2_index = offset_to_l2_slice_index(s, offset);
|
|
|
|
*new_l2_slice = l2_slice;
|
|
*new_l2_index = l2_index;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* alloc_compressed_cluster_offset
|
|
*
|
|
* For a given offset on the virtual disk, allocate a new compressed cluster
|
|
* and put the host offset of the cluster into *host_offset. If a cluster is
|
|
* already allocated at the offset, return an error.
|
|
*
|
|
* Return 0 on success and -errno in error cases
|
|
*/
|
|
int qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
|
|
uint64_t offset,
|
|
int compressed_size,
|
|
uint64_t *host_offset)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
int l2_index, ret;
|
|
uint64_t *l2_slice;
|
|
int64_t cluster_offset;
|
|
int nb_csectors;
|
|
|
|
if (has_data_file(bs)) {
|
|
return 0;
|
|
}
|
|
|
|
ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
/* Compression can't overwrite anything. Fail if the cluster was already
|
|
* allocated. */
|
|
cluster_offset = get_l2_entry(s, l2_slice, l2_index);
|
|
if (cluster_offset & L2E_OFFSET_MASK) {
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
return -EIO;
|
|
}
|
|
|
|
cluster_offset = qcow2_alloc_bytes(bs, compressed_size);
|
|
if (cluster_offset < 0) {
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
return cluster_offset;
|
|
}
|
|
|
|
nb_csectors =
|
|
(cluster_offset + compressed_size - 1) / QCOW2_COMPRESSED_SECTOR_SIZE -
|
|
(cluster_offset / QCOW2_COMPRESSED_SECTOR_SIZE);
|
|
|
|
/* The offset and size must fit in their fields of the L2 table entry */
|
|
assert((cluster_offset & s->cluster_offset_mask) == cluster_offset);
|
|
assert((nb_csectors & s->csize_mask) == nb_csectors);
|
|
|
|
cluster_offset |= QCOW_OFLAG_COMPRESSED |
|
|
((uint64_t)nb_csectors << s->csize_shift);
|
|
|
|
/* update L2 table */
|
|
|
|
/* compressed clusters never have the copied flag */
|
|
|
|
BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED);
|
|
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
|
|
set_l2_entry(s, l2_slice, l2_index, cluster_offset);
|
|
if (has_subclusters(s)) {
|
|
set_l2_bitmap(s, l2_slice, l2_index, 0);
|
|
}
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
|
|
*host_offset = cluster_offset & s->cluster_offset_mask;
|
|
return 0;
|
|
}
|
|
|
|
static int coroutine_fn perform_cow(BlockDriverState *bs, QCowL2Meta *m)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
Qcow2COWRegion *start = &m->cow_start;
|
|
Qcow2COWRegion *end = &m->cow_end;
|
|
unsigned buffer_size;
|
|
unsigned data_bytes = end->offset - (start->offset + start->nb_bytes);
|
|
bool merge_reads;
|
|
uint8_t *start_buffer, *end_buffer;
|
|
QEMUIOVector qiov;
|
|
int ret;
|
|
|
|
assert(start->nb_bytes <= UINT_MAX - end->nb_bytes);
|
|
assert(start->nb_bytes + end->nb_bytes <= UINT_MAX - data_bytes);
|
|
assert(start->offset + start->nb_bytes <= end->offset);
|
|
|
|
if ((start->nb_bytes == 0 && end->nb_bytes == 0) || m->skip_cow) {
|
|
return 0;
|
|
}
|
|
|
|
/* If we have to read both the start and end COW regions and the
|
|
* middle region is not too large then perform just one read
|
|
* operation */
|
|
merge_reads = start->nb_bytes && end->nb_bytes && data_bytes <= 16384;
|
|
if (merge_reads) {
|
|
buffer_size = start->nb_bytes + data_bytes + end->nb_bytes;
|
|
} else {
|
|
/* If we have to do two reads, add some padding in the middle
|
|
* if necessary to make sure that the end region is optimally
|
|
* aligned. */
|
|
size_t align = bdrv_opt_mem_align(bs);
|
|
assert(align > 0 && align <= UINT_MAX);
|
|
assert(QEMU_ALIGN_UP(start->nb_bytes, align) <=
|
|
UINT_MAX - end->nb_bytes);
|
|
buffer_size = QEMU_ALIGN_UP(start->nb_bytes, align) + end->nb_bytes;
|
|
}
|
|
|
|
/* Reserve a buffer large enough to store all the data that we're
|
|
* going to read */
|
|
start_buffer = qemu_try_blockalign(bs, buffer_size);
|
|
if (start_buffer == NULL) {
|
|
return -ENOMEM;
|
|
}
|
|
/* The part of the buffer where the end region is located */
|
|
end_buffer = start_buffer + buffer_size - end->nb_bytes;
|
|
|
|
qemu_iovec_init(&qiov, 2 + (m->data_qiov ?
|
|
qemu_iovec_subvec_niov(m->data_qiov,
|
|
m->data_qiov_offset,
|
|
data_bytes)
|
|
: 0));
|
|
|
|
qemu_co_mutex_unlock(&s->lock);
|
|
/* First we read the existing data from both COW regions. We
|
|
* either read the whole region in one go, or the start and end
|
|
* regions separately. */
|
|
if (merge_reads) {
|
|
qemu_iovec_add(&qiov, start_buffer, buffer_size);
|
|
ret = do_perform_cow_read(bs, m->offset, start->offset, &qiov);
|
|
} else {
|
|
qemu_iovec_add(&qiov, start_buffer, start->nb_bytes);
|
|
ret = do_perform_cow_read(bs, m->offset, start->offset, &qiov);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
qemu_iovec_reset(&qiov);
|
|
qemu_iovec_add(&qiov, end_buffer, end->nb_bytes);
|
|
ret = do_perform_cow_read(bs, m->offset, end->offset, &qiov);
|
|
}
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
/* Encrypt the data if necessary before writing it */
|
|
if (bs->encrypted) {
|
|
ret = qcow2_co_encrypt(bs,
|
|
m->alloc_offset + start->offset,
|
|
m->offset + start->offset,
|
|
start_buffer, start->nb_bytes);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
ret = qcow2_co_encrypt(bs,
|
|
m->alloc_offset + end->offset,
|
|
m->offset + end->offset,
|
|
end_buffer, end->nb_bytes);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
}
|
|
|
|
/* And now we can write everything. If we have the guest data we
|
|
* can write everything in one single operation */
|
|
if (m->data_qiov) {
|
|
qemu_iovec_reset(&qiov);
|
|
if (start->nb_bytes) {
|
|
qemu_iovec_add(&qiov, start_buffer, start->nb_bytes);
|
|
}
|
|
qemu_iovec_concat(&qiov, m->data_qiov, m->data_qiov_offset, data_bytes);
|
|
if (end->nb_bytes) {
|
|
qemu_iovec_add(&qiov, end_buffer, end->nb_bytes);
|
|
}
|
|
/* NOTE: we have a write_aio blkdebug event here followed by
|
|
* a cow_write one in do_perform_cow_write(), but there's only
|
|
* one single I/O operation */
|
|
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
|
|
ret = do_perform_cow_write(bs, m->alloc_offset, start->offset, &qiov);
|
|
} else {
|
|
/* If there's no guest data then write both COW regions separately */
|
|
qemu_iovec_reset(&qiov);
|
|
qemu_iovec_add(&qiov, start_buffer, start->nb_bytes);
|
|
ret = do_perform_cow_write(bs, m->alloc_offset, start->offset, &qiov);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
qemu_iovec_reset(&qiov);
|
|
qemu_iovec_add(&qiov, end_buffer, end->nb_bytes);
|
|
ret = do_perform_cow_write(bs, m->alloc_offset, end->offset, &qiov);
|
|
}
|
|
|
|
fail:
|
|
qemu_co_mutex_lock(&s->lock);
|
|
|
|
/*
|
|
* Before we update the L2 table to actually point to the new cluster, we
|
|
* need to be sure that the refcounts have been increased and COW was
|
|
* handled.
|
|
*/
|
|
if (ret == 0) {
|
|
qcow2_cache_depends_on_flush(s->l2_table_cache);
|
|
}
|
|
|
|
qemu_vfree(start_buffer);
|
|
qemu_iovec_destroy(&qiov);
|
|
return ret;
|
|
}
|
|
|
|
int coroutine_fn qcow2_alloc_cluster_link_l2(BlockDriverState *bs,
|
|
QCowL2Meta *m)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
int i, j = 0, l2_index, ret;
|
|
uint64_t *old_cluster, *l2_slice;
|
|
uint64_t cluster_offset = m->alloc_offset;
|
|
|
|
trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters);
|
|
assert(m->nb_clusters > 0);
|
|
|
|
old_cluster = g_try_new(uint64_t, m->nb_clusters);
|
|
if (old_cluster == NULL) {
|
|
ret = -ENOMEM;
|
|
goto err;
|
|
}
|
|
|
|
/* copy content of unmodified sectors */
|
|
ret = perform_cow(bs, m);
|
|
if (ret < 0) {
|
|
goto err;
|
|
}
|
|
|
|
/* Update L2 table. */
|
|
if (s->use_lazy_refcounts) {
|
|
qcow2_mark_dirty(bs);
|
|
}
|
|
if (qcow2_need_accurate_refcounts(s)) {
|
|
qcow2_cache_set_dependency(bs, s->l2_table_cache,
|
|
s->refcount_block_cache);
|
|
}
|
|
|
|
ret = get_cluster_table(bs, m->offset, &l2_slice, &l2_index);
|
|
if (ret < 0) {
|
|
goto err;
|
|
}
|
|
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
|
|
|
|
assert(l2_index + m->nb_clusters <= s->l2_slice_size);
|
|
assert(m->cow_end.offset + m->cow_end.nb_bytes <=
|
|
m->nb_clusters << s->cluster_bits);
|
|
for (i = 0; i < m->nb_clusters; i++) {
|
|
uint64_t offset = cluster_offset + ((uint64_t)i << s->cluster_bits);
|
|
/* if two concurrent writes happen to the same unallocated cluster
|
|
* each write allocates separate cluster and writes data concurrently.
|
|
* The first one to complete updates l2 table with pointer to its
|
|
* cluster the second one has to do RMW (which is done above by
|
|
* perform_cow()), update l2 table with its cluster pointer and free
|
|
* old cluster. This is what this loop does */
|
|
if (get_l2_entry(s, l2_slice, l2_index + i) != 0) {
|
|
old_cluster[j++] = get_l2_entry(s, l2_slice, l2_index + i);
|
|
}
|
|
|
|
/* The offset must fit in the offset field of the L2 table entry */
|
|
assert((offset & L2E_OFFSET_MASK) == offset);
|
|
|
|
set_l2_entry(s, l2_slice, l2_index + i, offset | QCOW_OFLAG_COPIED);
|
|
|
|
/* Update bitmap with the subclusters that were just written */
|
|
if (has_subclusters(s) && !m->prealloc) {
|
|
uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
|
|
unsigned written_from = m->cow_start.offset;
|
|
unsigned written_to = m->cow_end.offset + m->cow_end.nb_bytes;
|
|
int first_sc, last_sc;
|
|
/* Narrow written_from and written_to down to the current cluster */
|
|
written_from = MAX(written_from, i << s->cluster_bits);
|
|
written_to = MIN(written_to, (i + 1) << s->cluster_bits);
|
|
assert(written_from < written_to);
|
|
first_sc = offset_to_sc_index(s, written_from);
|
|
last_sc = offset_to_sc_index(s, written_to - 1);
|
|
l2_bitmap |= QCOW_OFLAG_SUB_ALLOC_RANGE(first_sc, last_sc + 1);
|
|
l2_bitmap &= ~QCOW_OFLAG_SUB_ZERO_RANGE(first_sc, last_sc + 1);
|
|
set_l2_bitmap(s, l2_slice, l2_index + i, l2_bitmap);
|
|
}
|
|
}
|
|
|
|
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
|
|
/*
|
|
* If this was a COW, we need to decrease the refcount of the old cluster.
|
|
*
|
|
* Don't discard clusters that reach a refcount of 0 (e.g. compressed
|
|
* clusters), the next write will reuse them anyway.
|
|
*/
|
|
if (!m->keep_old_clusters && j != 0) {
|
|
for (i = 0; i < j; i++) {
|
|
qcow2_free_any_cluster(bs, old_cluster[i], QCOW2_DISCARD_NEVER);
|
|
}
|
|
}
|
|
|
|
ret = 0;
|
|
err:
|
|
g_free(old_cluster);
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* Frees the allocated clusters because the request failed and they won't
|
|
* actually be linked.
|
|
*/
|
|
void qcow2_alloc_cluster_abort(BlockDriverState *bs, QCowL2Meta *m)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
if (!has_data_file(bs) && !m->keep_old_clusters) {
|
|
qcow2_free_clusters(bs, m->alloc_offset,
|
|
m->nb_clusters << s->cluster_bits,
|
|
QCOW2_DISCARD_NEVER);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* For a given write request, create a new QCowL2Meta structure, add
|
|
* it to @m and the BDRVQcow2State.cluster_allocs list. If the write
|
|
* request does not need copy-on-write or changes to the L2 metadata
|
|
* then this function does nothing.
|
|
*
|
|
* @host_cluster_offset points to the beginning of the first cluster.
|
|
*
|
|
* @guest_offset and @bytes indicate the offset and length of the
|
|
* request.
|
|
*
|
|
* @l2_slice contains the L2 entries of all clusters involved in this
|
|
* write request.
|
|
*
|
|
* If @keep_old is true it means that the clusters were already
|
|
* allocated and will be overwritten. If false then the clusters are
|
|
* new and we have to decrease the reference count of the old ones.
|
|
*
|
|
* Returns 0 on success, -errno on failure.
|
|
*/
|
|
static int calculate_l2_meta(BlockDriverState *bs, uint64_t host_cluster_offset,
|
|
uint64_t guest_offset, unsigned bytes,
|
|
uint64_t *l2_slice, QCowL2Meta **m, bool keep_old)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
int sc_index, l2_index = offset_to_l2_slice_index(s, guest_offset);
|
|
uint64_t l2_entry, l2_bitmap;
|
|
unsigned cow_start_from, cow_end_to;
|
|
unsigned cow_start_to = offset_into_cluster(s, guest_offset);
|
|
unsigned cow_end_from = cow_start_to + bytes;
|
|
unsigned nb_clusters = size_to_clusters(s, cow_end_from);
|
|
QCowL2Meta *old_m = *m;
|
|
QCow2SubclusterType type;
|
|
int i;
|
|
bool skip_cow = keep_old;
|
|
|
|
assert(nb_clusters <= s->l2_slice_size - l2_index);
|
|
|
|
/* Check the type of all affected subclusters */
|
|
for (i = 0; i < nb_clusters; i++) {
|
|
l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
|
|
l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
|
|
if (skip_cow) {
|
|
unsigned write_from = MAX(cow_start_to, i << s->cluster_bits);
|
|
unsigned write_to = MIN(cow_end_from, (i + 1) << s->cluster_bits);
|
|
int first_sc = offset_to_sc_index(s, write_from);
|
|
int last_sc = offset_to_sc_index(s, write_to - 1);
|
|
int cnt = qcow2_get_subcluster_range_type(bs, l2_entry, l2_bitmap,
|
|
first_sc, &type);
|
|
/* Is any of the subclusters of type != QCOW2_SUBCLUSTER_NORMAL ? */
|
|
if (type != QCOW2_SUBCLUSTER_NORMAL || first_sc + cnt <= last_sc) {
|
|
skip_cow = false;
|
|
}
|
|
} else {
|
|
/* If we can't skip the cow we can still look for invalid entries */
|
|
type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, 0);
|
|
}
|
|
if (type == QCOW2_SUBCLUSTER_INVALID) {
|
|
int l1_index = offset_to_l1_index(s, guest_offset);
|
|
uint64_t l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
|
|
qcow2_signal_corruption(bs, true, -1, -1, "Invalid cluster "
|
|
"entry found (L2 offset: %#" PRIx64
|
|
", L2 index: %#x)",
|
|
l2_offset, l2_index + i);
|
|
return -EIO;
|
|
}
|
|
}
|
|
|
|
if (skip_cow) {
|
|
return 0;
|
|
}
|
|
|
|
/* Get the L2 entry of the first cluster */
|
|
l2_entry = get_l2_entry(s, l2_slice, l2_index);
|
|
l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index);
|
|
sc_index = offset_to_sc_index(s, guest_offset);
|
|
type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index);
|
|
|
|
if (!keep_old) {
|
|
switch (type) {
|
|
case QCOW2_SUBCLUSTER_COMPRESSED:
|
|
cow_start_from = 0;
|
|
break;
|
|
case QCOW2_SUBCLUSTER_NORMAL:
|
|
case QCOW2_SUBCLUSTER_ZERO_ALLOC:
|
|
case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
|
|
if (has_subclusters(s)) {
|
|
/* Skip all leading zero and unallocated subclusters */
|
|
uint32_t alloc_bitmap = l2_bitmap & QCOW_L2_BITMAP_ALL_ALLOC;
|
|
cow_start_from =
|
|
MIN(sc_index, ctz32(alloc_bitmap)) << s->subcluster_bits;
|
|
} else {
|
|
cow_start_from = 0;
|
|
}
|
|
break;
|
|
case QCOW2_SUBCLUSTER_ZERO_PLAIN:
|
|
case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
|
|
cow_start_from = sc_index << s->subcluster_bits;
|
|
break;
|
|
default:
|
|
g_assert_not_reached();
|
|
}
|
|
} else {
|
|
switch (type) {
|
|
case QCOW2_SUBCLUSTER_NORMAL:
|
|
cow_start_from = cow_start_to;
|
|
break;
|
|
case QCOW2_SUBCLUSTER_ZERO_ALLOC:
|
|
case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
|
|
cow_start_from = sc_index << s->subcluster_bits;
|
|
break;
|
|
default:
|
|
g_assert_not_reached();
|
|
}
|
|
}
|
|
|
|
/* Get the L2 entry of the last cluster */
|
|
l2_index += nb_clusters - 1;
|
|
l2_entry = get_l2_entry(s, l2_slice, l2_index);
|
|
l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index);
|
|
sc_index = offset_to_sc_index(s, guest_offset + bytes - 1);
|
|
type = qcow2_get_subcluster_type(bs, l2_entry, l2_bitmap, sc_index);
|
|
|
|
if (!keep_old) {
|
|
switch (type) {
|
|
case QCOW2_SUBCLUSTER_COMPRESSED:
|
|
cow_end_to = ROUND_UP(cow_end_from, s->cluster_size);
|
|
break;
|
|
case QCOW2_SUBCLUSTER_NORMAL:
|
|
case QCOW2_SUBCLUSTER_ZERO_ALLOC:
|
|
case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
|
|
cow_end_to = ROUND_UP(cow_end_from, s->cluster_size);
|
|
if (has_subclusters(s)) {
|
|
/* Skip all trailing zero and unallocated subclusters */
|
|
uint32_t alloc_bitmap = l2_bitmap & QCOW_L2_BITMAP_ALL_ALLOC;
|
|
cow_end_to -=
|
|
MIN(s->subclusters_per_cluster - sc_index - 1,
|
|
clz32(alloc_bitmap)) << s->subcluster_bits;
|
|
}
|
|
break;
|
|
case QCOW2_SUBCLUSTER_ZERO_PLAIN:
|
|
case QCOW2_SUBCLUSTER_UNALLOCATED_PLAIN:
|
|
cow_end_to = ROUND_UP(cow_end_from, s->subcluster_size);
|
|
break;
|
|
default:
|
|
g_assert_not_reached();
|
|
}
|
|
} else {
|
|
switch (type) {
|
|
case QCOW2_SUBCLUSTER_NORMAL:
|
|
cow_end_to = cow_end_from;
|
|
break;
|
|
case QCOW2_SUBCLUSTER_ZERO_ALLOC:
|
|
case QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC:
|
|
cow_end_to = ROUND_UP(cow_end_from, s->subcluster_size);
|
|
break;
|
|
default:
|
|
g_assert_not_reached();
|
|
}
|
|
}
|
|
|
|
*m = g_malloc0(sizeof(**m));
|
|
**m = (QCowL2Meta) {
|
|
.next = old_m,
|
|
|
|
.alloc_offset = host_cluster_offset,
|
|
.offset = start_of_cluster(s, guest_offset),
|
|
.nb_clusters = nb_clusters,
|
|
|
|
.keep_old_clusters = keep_old,
|
|
|
|
.cow_start = {
|
|
.offset = cow_start_from,
|
|
.nb_bytes = cow_start_to - cow_start_from,
|
|
},
|
|
.cow_end = {
|
|
.offset = cow_end_from,
|
|
.nb_bytes = cow_end_to - cow_end_from,
|
|
},
|
|
};
|
|
|
|
qemu_co_queue_init(&(*m)->dependent_requests);
|
|
QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Returns true if writing to the cluster pointed to by @l2_entry
|
|
* requires a new allocation (that is, if the cluster is unallocated
|
|
* or has refcount > 1 and therefore cannot be written in-place).
|
|
*/
|
|
static bool cluster_needs_new_alloc(BlockDriverState *bs, uint64_t l2_entry)
|
|
{
|
|
switch (qcow2_get_cluster_type(bs, l2_entry)) {
|
|
case QCOW2_CLUSTER_NORMAL:
|
|
case QCOW2_CLUSTER_ZERO_ALLOC:
|
|
if (l2_entry & QCOW_OFLAG_COPIED) {
|
|
return false;
|
|
}
|
|
/* fallthrough */
|
|
case QCOW2_CLUSTER_UNALLOCATED:
|
|
case QCOW2_CLUSTER_COMPRESSED:
|
|
case QCOW2_CLUSTER_ZERO_PLAIN:
|
|
return true;
|
|
default:
|
|
abort();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Returns the number of contiguous clusters that can be written to
|
|
* using one single write request, starting from @l2_index.
|
|
* At most @nb_clusters are checked.
|
|
*
|
|
* If @new_alloc is true this counts clusters that are either
|
|
* unallocated, or allocated but with refcount > 1 (so they need to be
|
|
* newly allocated and COWed).
|
|
*
|
|
* If @new_alloc is false this counts clusters that are already
|
|
* allocated and can be overwritten in-place (this includes clusters
|
|
* of type QCOW2_CLUSTER_ZERO_ALLOC).
|
|
*/
|
|
static int count_single_write_clusters(BlockDriverState *bs, int nb_clusters,
|
|
uint64_t *l2_slice, int l2_index,
|
|
bool new_alloc)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
uint64_t l2_entry = get_l2_entry(s, l2_slice, l2_index);
|
|
uint64_t expected_offset = l2_entry & L2E_OFFSET_MASK;
|
|
int i;
|
|
|
|
for (i = 0; i < nb_clusters; i++) {
|
|
l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
|
|
if (cluster_needs_new_alloc(bs, l2_entry) != new_alloc) {
|
|
break;
|
|
}
|
|
if (!new_alloc) {
|
|
if (expected_offset != (l2_entry & L2E_OFFSET_MASK)) {
|
|
break;
|
|
}
|
|
expected_offset += s->cluster_size;
|
|
}
|
|
}
|
|
|
|
assert(i <= nb_clusters);
|
|
return i;
|
|
}
|
|
|
|
/*
|
|
* Check if there already is an AIO write request in flight which allocates
|
|
* the same cluster. In this case we need to wait until the previous
|
|
* request has completed and updated the L2 table accordingly.
|
|
*
|
|
* Returns:
|
|
* 0 if there was no dependency. *cur_bytes indicates the number of
|
|
* bytes from guest_offset that can be read before the next
|
|
* dependency must be processed (or the request is complete)
|
|
*
|
|
* -EAGAIN if we had to wait for another request, previously gathered
|
|
* information on cluster allocation may be invalid now. The caller
|
|
* must start over anyway, so consider *cur_bytes undefined.
|
|
*/
|
|
static int coroutine_fn handle_dependencies(BlockDriverState *bs,
|
|
uint64_t guest_offset,
|
|
uint64_t *cur_bytes, QCowL2Meta **m)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
QCowL2Meta *old_alloc;
|
|
uint64_t bytes = *cur_bytes;
|
|
|
|
QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) {
|
|
|
|
uint64_t start = guest_offset;
|
|
uint64_t end = start + bytes;
|
|
uint64_t old_start = start_of_cluster(s, l2meta_cow_start(old_alloc));
|
|
uint64_t old_end = ROUND_UP(l2meta_cow_end(old_alloc), s->cluster_size);
|
|
|
|
if (end <= old_start || start >= old_end) {
|
|
/* No intersection */
|
|
continue;
|
|
}
|
|
|
|
if (old_alloc->keep_old_clusters &&
|
|
(end <= l2meta_cow_start(old_alloc) ||
|
|
start >= l2meta_cow_end(old_alloc)))
|
|
{
|
|
/*
|
|
* Clusters intersect but COW areas don't. And cluster itself is
|
|
* already allocated. So, there is no actual conflict.
|
|
*/
|
|
continue;
|
|
}
|
|
|
|
/* Conflict */
|
|
|
|
if (start < old_start) {
|
|
/* Stop at the start of a running allocation */
|
|
bytes = old_start - start;
|
|
} else {
|
|
bytes = 0;
|
|
}
|
|
|
|
/*
|
|
* Stop if an l2meta already exists. After yielding, it wouldn't
|
|
* be valid any more, so we'd have to clean up the old L2Metas
|
|
* and deal with requests depending on them before starting to
|
|
* gather new ones. Not worth the trouble.
|
|
*/
|
|
if (bytes == 0 && *m) {
|
|
*cur_bytes = 0;
|
|
return 0;
|
|
}
|
|
|
|
if (bytes == 0) {
|
|
/*
|
|
* Wait for the dependency to complete. We need to recheck
|
|
* the free/allocated clusters when we continue.
|
|
*/
|
|
qemu_co_queue_wait(&old_alloc->dependent_requests, &s->lock);
|
|
return -EAGAIN;
|
|
}
|
|
}
|
|
|
|
/* Make sure that existing clusters and new allocations are only used up to
|
|
* the next dependency if we shortened the request above */
|
|
*cur_bytes = bytes;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Checks how many already allocated clusters that don't require a new
|
|
* allocation there are at the given guest_offset (up to *bytes).
|
|
* If *host_offset is not INV_OFFSET, only physically contiguous clusters
|
|
* beginning at this host offset are counted.
|
|
*
|
|
* Note that guest_offset may not be cluster aligned. In this case, the
|
|
* returned *host_offset points to exact byte referenced by guest_offset and
|
|
* therefore isn't cluster aligned as well.
|
|
*
|
|
* Returns:
|
|
* 0: if no allocated clusters are available at the given offset.
|
|
* *bytes is normally unchanged. It is set to 0 if the cluster
|
|
* is allocated and can be overwritten in-place but doesn't have
|
|
* the right physical offset.
|
|
*
|
|
* 1: if allocated clusters that can be overwritten in place are
|
|
* available at the requested offset. *bytes may have decreased
|
|
* and describes the length of the area that can be written to.
|
|
*
|
|
* -errno: in error cases
|
|
*/
|
|
static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
|
|
uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
int l2_index;
|
|
uint64_t l2_entry, cluster_offset;
|
|
uint64_t *l2_slice;
|
|
uint64_t nb_clusters;
|
|
unsigned int keep_clusters;
|
|
int ret;
|
|
|
|
trace_qcow2_handle_copied(qemu_coroutine_self(), guest_offset, *host_offset,
|
|
*bytes);
|
|
|
|
assert(*host_offset == INV_OFFSET || offset_into_cluster(s, guest_offset)
|
|
== offset_into_cluster(s, *host_offset));
|
|
|
|
/*
|
|
* Calculate the number of clusters to look for. We stop at L2 slice
|
|
* boundaries to keep things simple.
|
|
*/
|
|
nb_clusters =
|
|
size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
|
|
|
|
l2_index = offset_to_l2_slice_index(s, guest_offset);
|
|
nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
|
|
/* Limit total byte count to BDRV_REQUEST_MAX_BYTES */
|
|
nb_clusters = MIN(nb_clusters, BDRV_REQUEST_MAX_BYTES >> s->cluster_bits);
|
|
|
|
/* Find L2 entry for the first involved cluster */
|
|
ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
l2_entry = get_l2_entry(s, l2_slice, l2_index);
|
|
cluster_offset = l2_entry & L2E_OFFSET_MASK;
|
|
|
|
if (!cluster_needs_new_alloc(bs, l2_entry)) {
|
|
if (offset_into_cluster(s, cluster_offset)) {
|
|
qcow2_signal_corruption(bs, true, -1, -1, "%s cluster offset "
|
|
"%#" PRIx64 " unaligned (guest offset: %#"
|
|
PRIx64 ")", l2_entry & QCOW_OFLAG_ZERO ?
|
|
"Preallocated zero" : "Data",
|
|
cluster_offset, guest_offset);
|
|
ret = -EIO;
|
|
goto out;
|
|
}
|
|
|
|
/* If a specific host_offset is required, check it */
|
|
if (*host_offset != INV_OFFSET && cluster_offset != *host_offset) {
|
|
*bytes = 0;
|
|
ret = 0;
|
|
goto out;
|
|
}
|
|
|
|
/* We keep all QCOW_OFLAG_COPIED clusters */
|
|
keep_clusters = count_single_write_clusters(bs, nb_clusters, l2_slice,
|
|
l2_index, false);
|
|
assert(keep_clusters <= nb_clusters);
|
|
|
|
*bytes = MIN(*bytes,
|
|
keep_clusters * s->cluster_size
|
|
- offset_into_cluster(s, guest_offset));
|
|
assert(*bytes != 0);
|
|
|
|
ret = calculate_l2_meta(bs, cluster_offset, guest_offset,
|
|
*bytes, l2_slice, m, true);
|
|
if (ret < 0) {
|
|
goto out;
|
|
}
|
|
|
|
ret = 1;
|
|
} else {
|
|
ret = 0;
|
|
}
|
|
|
|
/* Cleanup */
|
|
out:
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
|
|
/* Only return a host offset if we actually made progress. Otherwise we
|
|
* would make requirements for handle_alloc() that it can't fulfill */
|
|
if (ret > 0) {
|
|
*host_offset = cluster_offset + offset_into_cluster(s, guest_offset);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Allocates new clusters for the given guest_offset.
|
|
*
|
|
* At most *nb_clusters are allocated, and on return *nb_clusters is updated to
|
|
* contain the number of clusters that have been allocated and are contiguous
|
|
* in the image file.
|
|
*
|
|
* If *host_offset is not INV_OFFSET, it specifies the offset in the image file
|
|
* at which the new clusters must start. *nb_clusters can be 0 on return in
|
|
* this case if the cluster at host_offset is already in use. If *host_offset
|
|
* is INV_OFFSET, the clusters can be allocated anywhere in the image file.
|
|
*
|
|
* *host_offset is updated to contain the offset into the image file at which
|
|
* the first allocated cluster starts.
|
|
*
|
|
* Return 0 on success and -errno in error cases. -EAGAIN means that the
|
|
* function has been waiting for another request and the allocation must be
|
|
* restarted, but the whole request should not be failed.
|
|
*/
|
|
static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
|
|
uint64_t *host_offset, uint64_t *nb_clusters)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
|
|
trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset,
|
|
*host_offset, *nb_clusters);
|
|
|
|
if (has_data_file(bs)) {
|
|
assert(*host_offset == INV_OFFSET ||
|
|
*host_offset == start_of_cluster(s, guest_offset));
|
|
*host_offset = start_of_cluster(s, guest_offset);
|
|
return 0;
|
|
}
|
|
|
|
/* Allocate new clusters */
|
|
trace_qcow2_cluster_alloc_phys(qemu_coroutine_self());
|
|
if (*host_offset == INV_OFFSET) {
|
|
int64_t cluster_offset =
|
|
qcow2_alloc_clusters(bs, *nb_clusters * s->cluster_size);
|
|
if (cluster_offset < 0) {
|
|
return cluster_offset;
|
|
}
|
|
*host_offset = cluster_offset;
|
|
return 0;
|
|
} else {
|
|
int64_t ret = qcow2_alloc_clusters_at(bs, *host_offset, *nb_clusters);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
*nb_clusters = ret;
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocates new clusters for an area that is either still unallocated or
|
|
* cannot be overwritten in-place. If *host_offset is not INV_OFFSET,
|
|
* clusters are only allocated if the new allocation can match the specified
|
|
* host offset.
|
|
*
|
|
* Note that guest_offset may not be cluster aligned. In this case, the
|
|
* returned *host_offset points to exact byte referenced by guest_offset and
|
|
* therefore isn't cluster aligned as well.
|
|
*
|
|
* Returns:
|
|
* 0: if no clusters could be allocated. *bytes is set to 0,
|
|
* *host_offset is left unchanged.
|
|
*
|
|
* 1: if new clusters were allocated. *bytes may be decreased if the
|
|
* new allocation doesn't cover all of the requested area.
|
|
* *host_offset is updated to contain the host offset of the first
|
|
* newly allocated cluster.
|
|
*
|
|
* -errno: in error cases
|
|
*/
|
|
static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
|
|
uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
int l2_index;
|
|
uint64_t *l2_slice;
|
|
uint64_t nb_clusters;
|
|
int ret;
|
|
|
|
uint64_t alloc_cluster_offset;
|
|
|
|
trace_qcow2_handle_alloc(qemu_coroutine_self(), guest_offset, *host_offset,
|
|
*bytes);
|
|
assert(*bytes > 0);
|
|
|
|
/*
|
|
* Calculate the number of clusters to look for. We stop at L2 slice
|
|
* boundaries to keep things simple.
|
|
*/
|
|
nb_clusters =
|
|
size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
|
|
|
|
l2_index = offset_to_l2_slice_index(s, guest_offset);
|
|
nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
|
|
/* Limit total allocation byte count to BDRV_REQUEST_MAX_BYTES */
|
|
nb_clusters = MIN(nb_clusters, BDRV_REQUEST_MAX_BYTES >> s->cluster_bits);
|
|
|
|
/* Find L2 entry for the first involved cluster */
|
|
ret = get_cluster_table(bs, guest_offset, &l2_slice, &l2_index);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
nb_clusters = count_single_write_clusters(bs, nb_clusters,
|
|
l2_slice, l2_index, true);
|
|
|
|
/* This function is only called when there were no non-COW clusters, so if
|
|
* we can't find any unallocated or COW clusters either, something is
|
|
* wrong with our code. */
|
|
assert(nb_clusters > 0);
|
|
|
|
/* Allocate at a given offset in the image file */
|
|
alloc_cluster_offset = *host_offset == INV_OFFSET ? INV_OFFSET :
|
|
start_of_cluster(s, *host_offset);
|
|
ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset,
|
|
&nb_clusters);
|
|
if (ret < 0) {
|
|
goto out;
|
|
}
|
|
|
|
/* Can't extend contiguous allocation */
|
|
if (nb_clusters == 0) {
|
|
*bytes = 0;
|
|
ret = 0;
|
|
goto out;
|
|
}
|
|
|
|
assert(alloc_cluster_offset != INV_OFFSET);
|
|
|
|
/*
|
|
* Save info needed for meta data update.
|
|
*
|
|
* requested_bytes: Number of bytes from the start of the first
|
|
* newly allocated cluster to the end of the (possibly shortened
|
|
* before) write request.
|
|
*
|
|
* avail_bytes: Number of bytes from the start of the first
|
|
* newly allocated to the end of the last newly allocated cluster.
|
|
*
|
|
* nb_bytes: The number of bytes from the start of the first
|
|
* newly allocated cluster to the end of the area that the write
|
|
* request actually writes to (excluding COW at the end)
|
|
*/
|
|
uint64_t requested_bytes = *bytes + offset_into_cluster(s, guest_offset);
|
|
int avail_bytes = nb_clusters << s->cluster_bits;
|
|
int nb_bytes = MIN(requested_bytes, avail_bytes);
|
|
|
|
*host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset);
|
|
*bytes = MIN(*bytes, nb_bytes - offset_into_cluster(s, guest_offset));
|
|
assert(*bytes != 0);
|
|
|
|
ret = calculate_l2_meta(bs, alloc_cluster_offset, guest_offset, *bytes,
|
|
l2_slice, m, false);
|
|
if (ret < 0) {
|
|
goto out;
|
|
}
|
|
|
|
ret = 1;
|
|
|
|
out:
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* For a given area on the virtual disk defined by @offset and @bytes,
|
|
* find the corresponding area on the qcow2 image, allocating new
|
|
* clusters (or subclusters) if necessary. The result can span a
|
|
* combination of allocated and previously unallocated clusters.
|
|
*
|
|
* Note that offset may not be cluster aligned. In this case, the returned
|
|
* *host_offset points to exact byte referenced by offset and therefore
|
|
* isn't cluster aligned as well.
|
|
*
|
|
* On return, @host_offset is set to the beginning of the requested
|
|
* area. This area is guaranteed to be contiguous on the qcow2 file
|
|
* but it can be smaller than initially requested. In this case @bytes
|
|
* is updated with the actual size.
|
|
*
|
|
* If any clusters or subclusters were allocated then @m contains a
|
|
* list with the information of all the affected regions. Note that
|
|
* this can happen regardless of whether this function succeeds or
|
|
* not. The caller is responsible for updating the L2 metadata of the
|
|
* allocated clusters (on success) or freeing them (on failure), and
|
|
* for clearing the contents of @m afterwards in both cases.
|
|
*
|
|
* If the request conflicts with another write request in flight, the coroutine
|
|
* is queued and will be reentered when the dependency has completed.
|
|
*
|
|
* Return 0 on success and -errno in error cases
|
|
*/
|
|
int coroutine_fn qcow2_alloc_host_offset(BlockDriverState *bs, uint64_t offset,
|
|
unsigned int *bytes,
|
|
uint64_t *host_offset,
|
|
QCowL2Meta **m)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
uint64_t start, remaining;
|
|
uint64_t cluster_offset;
|
|
uint64_t cur_bytes;
|
|
int ret;
|
|
|
|
trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset, *bytes);
|
|
|
|
again:
|
|
start = offset;
|
|
remaining = *bytes;
|
|
cluster_offset = INV_OFFSET;
|
|
*host_offset = INV_OFFSET;
|
|
cur_bytes = 0;
|
|
*m = NULL;
|
|
|
|
while (true) {
|
|
|
|
if (*host_offset == INV_OFFSET && cluster_offset != INV_OFFSET) {
|
|
*host_offset = cluster_offset;
|
|
}
|
|
|
|
assert(remaining >= cur_bytes);
|
|
|
|
start += cur_bytes;
|
|
remaining -= cur_bytes;
|
|
|
|
if (cluster_offset != INV_OFFSET) {
|
|
cluster_offset += cur_bytes;
|
|
}
|
|
|
|
if (remaining == 0) {
|
|
break;
|
|
}
|
|
|
|
cur_bytes = remaining;
|
|
|
|
/*
|
|
* Now start gathering as many contiguous clusters as possible:
|
|
*
|
|
* 1. Check for overlaps with in-flight allocations
|
|
*
|
|
* a) Overlap not in the first cluster -> shorten this request and
|
|
* let the caller handle the rest in its next loop iteration.
|
|
*
|
|
* b) Real overlaps of two requests. Yield and restart the search
|
|
* for contiguous clusters (the situation could have changed
|
|
* while we were sleeping)
|
|
*
|
|
* c) TODO: Request starts in the same cluster as the in-flight
|
|
* allocation ends. Shorten the COW of the in-fight allocation,
|
|
* set cluster_offset to write to the same cluster and set up
|
|
* the right synchronisation between the in-flight request and
|
|
* the new one.
|
|
*/
|
|
ret = handle_dependencies(bs, start, &cur_bytes, m);
|
|
if (ret == -EAGAIN) {
|
|
/* Currently handle_dependencies() doesn't yield if we already had
|
|
* an allocation. If it did, we would have to clean up the L2Meta
|
|
* structs before starting over. */
|
|
assert(*m == NULL);
|
|
goto again;
|
|
} else if (ret < 0) {
|
|
return ret;
|
|
} else if (cur_bytes == 0) {
|
|
break;
|
|
} else {
|
|
/* handle_dependencies() may have decreased cur_bytes (shortened
|
|
* the allocations below) so that the next dependency is processed
|
|
* correctly during the next loop iteration. */
|
|
}
|
|
|
|
/*
|
|
* 2. Count contiguous COPIED clusters.
|
|
*/
|
|
ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m);
|
|
if (ret < 0) {
|
|
return ret;
|
|
} else if (ret) {
|
|
continue;
|
|
} else if (cur_bytes == 0) {
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* 3. If the request still hasn't completed, allocate new clusters,
|
|
* considering any cluster_offset of steps 1c or 2.
|
|
*/
|
|
ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m);
|
|
if (ret < 0) {
|
|
return ret;
|
|
} else if (ret) {
|
|
continue;
|
|
} else {
|
|
assert(cur_bytes == 0);
|
|
break;
|
|
}
|
|
}
|
|
|
|
*bytes -= remaining;
|
|
assert(*bytes > 0);
|
|
assert(*host_offset != INV_OFFSET);
|
|
assert(offset_into_cluster(s, *host_offset) ==
|
|
offset_into_cluster(s, offset));
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* This discards as many clusters of nb_clusters as possible at once (i.e.
|
|
* all clusters in the same L2 slice) and returns the number of discarded
|
|
* clusters.
|
|
*/
|
|
static int discard_in_l2_slice(BlockDriverState *bs, uint64_t offset,
|
|
uint64_t nb_clusters,
|
|
enum qcow2_discard_type type, bool full_discard)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
uint64_t *l2_slice;
|
|
int l2_index;
|
|
int ret;
|
|
int i;
|
|
|
|
ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
/* Limit nb_clusters to one L2 slice */
|
|
nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
|
|
assert(nb_clusters <= INT_MAX);
|
|
|
|
for (i = 0; i < nb_clusters; i++) {
|
|
uint64_t old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
|
|
uint64_t old_l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
|
|
uint64_t new_l2_entry = old_l2_entry;
|
|
uint64_t new_l2_bitmap = old_l2_bitmap;
|
|
QCow2ClusterType cluster_type =
|
|
qcow2_get_cluster_type(bs, old_l2_entry);
|
|
|
|
/*
|
|
* If full_discard is true, the cluster should not read back as zeroes,
|
|
* but rather fall through to the backing file.
|
|
*
|
|
* If full_discard is false, make sure that a discarded area reads back
|
|
* as zeroes for v3 images (we cannot do it for v2 without actually
|
|
* writing a zero-filled buffer). We can skip the operation if the
|
|
* cluster is already marked as zero, or if it's unallocated and we
|
|
* don't have a backing file.
|
|
*
|
|
* TODO We might want to use bdrv_block_status(bs) here, but we're
|
|
* holding s->lock, so that doesn't work today.
|
|
*/
|
|
if (full_discard) {
|
|
new_l2_entry = new_l2_bitmap = 0;
|
|
} else if (bs->backing || qcow2_cluster_is_allocated(cluster_type)) {
|
|
if (has_subclusters(s)) {
|
|
new_l2_entry = 0;
|
|
new_l2_bitmap = QCOW_L2_BITMAP_ALL_ZEROES;
|
|
} else {
|
|
new_l2_entry = s->qcow_version >= 3 ? QCOW_OFLAG_ZERO : 0;
|
|
}
|
|
}
|
|
|
|
if (old_l2_entry == new_l2_entry && old_l2_bitmap == new_l2_bitmap) {
|
|
continue;
|
|
}
|
|
|
|
/* First remove L2 entries */
|
|
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
|
|
set_l2_entry(s, l2_slice, l2_index + i, new_l2_entry);
|
|
if (has_subclusters(s)) {
|
|
set_l2_bitmap(s, l2_slice, l2_index + i, new_l2_bitmap);
|
|
}
|
|
/* Then decrease the refcount */
|
|
qcow2_free_any_cluster(bs, old_l2_entry, type);
|
|
}
|
|
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
|
|
return nb_clusters;
|
|
}
|
|
|
|
int qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset,
|
|
uint64_t bytes, enum qcow2_discard_type type,
|
|
bool full_discard)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
uint64_t end_offset = offset + bytes;
|
|
uint64_t nb_clusters;
|
|
int64_t cleared;
|
|
int ret;
|
|
|
|
/* Caller must pass aligned values, except at image end */
|
|
assert(QEMU_IS_ALIGNED(offset, s->cluster_size));
|
|
assert(QEMU_IS_ALIGNED(end_offset, s->cluster_size) ||
|
|
end_offset == bs->total_sectors << BDRV_SECTOR_BITS);
|
|
|
|
nb_clusters = size_to_clusters(s, bytes);
|
|
|
|
s->cache_discards = true;
|
|
|
|
/* Each L2 slice is handled by its own loop iteration */
|
|
while (nb_clusters > 0) {
|
|
cleared = discard_in_l2_slice(bs, offset, nb_clusters, type,
|
|
full_discard);
|
|
if (cleared < 0) {
|
|
ret = cleared;
|
|
goto fail;
|
|
}
|
|
|
|
nb_clusters -= cleared;
|
|
offset += (cleared * s->cluster_size);
|
|
}
|
|
|
|
ret = 0;
|
|
fail:
|
|
s->cache_discards = false;
|
|
qcow2_process_discards(bs, ret);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This zeroes as many clusters of nb_clusters as possible at once (i.e.
|
|
* all clusters in the same L2 slice) and returns the number of zeroed
|
|
* clusters.
|
|
*/
|
|
static int zero_in_l2_slice(BlockDriverState *bs, uint64_t offset,
|
|
uint64_t nb_clusters, int flags)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
uint64_t *l2_slice;
|
|
int l2_index;
|
|
int ret;
|
|
int i;
|
|
|
|
ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
/* Limit nb_clusters to one L2 slice */
|
|
nb_clusters = MIN(nb_clusters, s->l2_slice_size - l2_index);
|
|
assert(nb_clusters <= INT_MAX);
|
|
|
|
for (i = 0; i < nb_clusters; i++) {
|
|
uint64_t old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
|
|
uint64_t old_l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
|
|
QCow2ClusterType type = qcow2_get_cluster_type(bs, old_l2_entry);
|
|
bool unmap = (type == QCOW2_CLUSTER_COMPRESSED) ||
|
|
((flags & BDRV_REQ_MAY_UNMAP) && qcow2_cluster_is_allocated(type));
|
|
uint64_t new_l2_entry = unmap ? 0 : old_l2_entry;
|
|
uint64_t new_l2_bitmap = old_l2_bitmap;
|
|
|
|
if (has_subclusters(s)) {
|
|
new_l2_bitmap = QCOW_L2_BITMAP_ALL_ZEROES;
|
|
} else {
|
|
new_l2_entry |= QCOW_OFLAG_ZERO;
|
|
}
|
|
|
|
if (old_l2_entry == new_l2_entry && old_l2_bitmap == new_l2_bitmap) {
|
|
continue;
|
|
}
|
|
|
|
/* First update L2 entries */
|
|
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
|
|
set_l2_entry(s, l2_slice, l2_index + i, new_l2_entry);
|
|
if (has_subclusters(s)) {
|
|
set_l2_bitmap(s, l2_slice, l2_index + i, new_l2_bitmap);
|
|
}
|
|
|
|
/* Then decrease the refcount */
|
|
if (unmap) {
|
|
qcow2_free_any_cluster(bs, old_l2_entry, QCOW2_DISCARD_REQUEST);
|
|
}
|
|
}
|
|
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
|
|
return nb_clusters;
|
|
}
|
|
|
|
static int zero_l2_subclusters(BlockDriverState *bs, uint64_t offset,
|
|
unsigned nb_subclusters)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
uint64_t *l2_slice;
|
|
uint64_t old_l2_bitmap, l2_bitmap;
|
|
int l2_index, ret, sc = offset_to_sc_index(s, offset);
|
|
|
|
/* For full clusters use zero_in_l2_slice() instead */
|
|
assert(nb_subclusters > 0 && nb_subclusters < s->subclusters_per_cluster);
|
|
assert(sc + nb_subclusters <= s->subclusters_per_cluster);
|
|
assert(offset_into_subcluster(s, offset) == 0);
|
|
|
|
ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
switch (qcow2_get_cluster_type(bs, get_l2_entry(s, l2_slice, l2_index))) {
|
|
case QCOW2_CLUSTER_COMPRESSED:
|
|
ret = -ENOTSUP; /* We cannot partially zeroize compressed clusters */
|
|
goto out;
|
|
case QCOW2_CLUSTER_NORMAL:
|
|
case QCOW2_CLUSTER_UNALLOCATED:
|
|
break;
|
|
default:
|
|
g_assert_not_reached();
|
|
}
|
|
|
|
old_l2_bitmap = l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index);
|
|
|
|
l2_bitmap |= QCOW_OFLAG_SUB_ZERO_RANGE(sc, sc + nb_subclusters);
|
|
l2_bitmap &= ~QCOW_OFLAG_SUB_ALLOC_RANGE(sc, sc + nb_subclusters);
|
|
|
|
if (old_l2_bitmap != l2_bitmap) {
|
|
set_l2_bitmap(s, l2_slice, l2_index, l2_bitmap);
|
|
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
|
|
}
|
|
|
|
ret = 0;
|
|
out:
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int coroutine_fn qcow2_subcluster_zeroize(BlockDriverState *bs, uint64_t offset,
|
|
uint64_t bytes, int flags)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
uint64_t end_offset = offset + bytes;
|
|
uint64_t nb_clusters;
|
|
unsigned head, tail;
|
|
int64_t cleared;
|
|
int ret;
|
|
|
|
/* If we have to stay in sync with an external data file, zero out
|
|
* s->data_file first. */
|
|
if (data_file_is_raw(bs)) {
|
|
assert(has_data_file(bs));
|
|
ret = bdrv_co_pwrite_zeroes(s->data_file, offset, bytes, flags);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
/* Caller must pass aligned values, except at image end */
|
|
assert(offset_into_subcluster(s, offset) == 0);
|
|
assert(offset_into_subcluster(s, end_offset) == 0 ||
|
|
end_offset >= bs->total_sectors << BDRV_SECTOR_BITS);
|
|
|
|
/*
|
|
* The zero flag is only supported by version 3 and newer. However, if we
|
|
* have no backing file, we can resort to discard in version 2.
|
|
*/
|
|
if (s->qcow_version < 3) {
|
|
if (!bs->backing) {
|
|
return qcow2_cluster_discard(bs, offset, bytes,
|
|
QCOW2_DISCARD_REQUEST, false);
|
|
}
|
|
return -ENOTSUP;
|
|
}
|
|
|
|
head = MIN(end_offset, ROUND_UP(offset, s->cluster_size)) - offset;
|
|
offset += head;
|
|
|
|
tail = (end_offset >= bs->total_sectors << BDRV_SECTOR_BITS) ? 0 :
|
|
end_offset - MAX(offset, start_of_cluster(s, end_offset));
|
|
end_offset -= tail;
|
|
|
|
s->cache_discards = true;
|
|
|
|
if (head) {
|
|
ret = zero_l2_subclusters(bs, offset - head,
|
|
size_to_subclusters(s, head));
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
}
|
|
|
|
/* Each L2 slice is handled by its own loop iteration */
|
|
nb_clusters = size_to_clusters(s, end_offset - offset);
|
|
|
|
while (nb_clusters > 0) {
|
|
cleared = zero_in_l2_slice(bs, offset, nb_clusters, flags);
|
|
if (cleared < 0) {
|
|
ret = cleared;
|
|
goto fail;
|
|
}
|
|
|
|
nb_clusters -= cleared;
|
|
offset += (cleared * s->cluster_size);
|
|
}
|
|
|
|
if (tail) {
|
|
ret = zero_l2_subclusters(bs, end_offset, size_to_subclusters(s, tail));
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
}
|
|
|
|
ret = 0;
|
|
fail:
|
|
s->cache_discards = false;
|
|
qcow2_process_discards(bs, ret);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Expands all zero clusters in a specific L1 table (or deallocates them, for
|
|
* non-backed non-pre-allocated zero clusters).
|
|
*
|
|
* l1_entries and *visited_l1_entries are used to keep track of progress for
|
|
* status_cb(). l1_entries contains the total number of L1 entries and
|
|
* *visited_l1_entries counts all visited L1 entries.
|
|
*/
|
|
static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
|
|
int l1_size, int64_t *visited_l1_entries,
|
|
int64_t l1_entries,
|
|
BlockDriverAmendStatusCB *status_cb,
|
|
void *cb_opaque)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
bool is_active_l1 = (l1_table == s->l1_table);
|
|
uint64_t *l2_slice = NULL;
|
|
unsigned slice, slice_size2, n_slices;
|
|
int ret;
|
|
int i, j;
|
|
|
|
/* qcow2_downgrade() is not allowed in images with subclusters */
|
|
assert(!has_subclusters(s));
|
|
|
|
slice_size2 = s->l2_slice_size * l2_entry_size(s);
|
|
n_slices = s->cluster_size / slice_size2;
|
|
|
|
if (!is_active_l1) {
|
|
/* inactive L2 tables require a buffer to be stored in when loading
|
|
* them from disk */
|
|
l2_slice = qemu_try_blockalign(bs->file->bs, slice_size2);
|
|
if (l2_slice == NULL) {
|
|
return -ENOMEM;
|
|
}
|
|
}
|
|
|
|
for (i = 0; i < l1_size; i++) {
|
|
uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK;
|
|
uint64_t l2_refcount;
|
|
|
|
if (!l2_offset) {
|
|
/* unallocated */
|
|
(*visited_l1_entries)++;
|
|
if (status_cb) {
|
|
status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque);
|
|
}
|
|
continue;
|
|
}
|
|
|
|
if (offset_into_cluster(s, l2_offset)) {
|
|
qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#"
|
|
PRIx64 " unaligned (L1 index: %#x)",
|
|
l2_offset, i);
|
|
ret = -EIO;
|
|
goto fail;
|
|
}
|
|
|
|
ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits,
|
|
&l2_refcount);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
for (slice = 0; slice < n_slices; slice++) {
|
|
uint64_t slice_offset = l2_offset + slice * slice_size2;
|
|
bool l2_dirty = false;
|
|
if (is_active_l1) {
|
|
/* get active L2 tables from cache */
|
|
ret = qcow2_cache_get(bs, s->l2_table_cache, slice_offset,
|
|
(void **)&l2_slice);
|
|
} else {
|
|
/* load inactive L2 tables from disk */
|
|
ret = bdrv_pread(bs->file, slice_offset, slice_size2,
|
|
l2_slice, 0);
|
|
}
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
for (j = 0; j < s->l2_slice_size; j++) {
|
|
uint64_t l2_entry = get_l2_entry(s, l2_slice, j);
|
|
int64_t offset = l2_entry & L2E_OFFSET_MASK;
|
|
QCow2ClusterType cluster_type =
|
|
qcow2_get_cluster_type(bs, l2_entry);
|
|
|
|
if (cluster_type != QCOW2_CLUSTER_ZERO_PLAIN &&
|
|
cluster_type != QCOW2_CLUSTER_ZERO_ALLOC) {
|
|
continue;
|
|
}
|
|
|
|
if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
|
|
if (!bs->backing) {
|
|
/*
|
|
* not backed; therefore we can simply deallocate the
|
|
* cluster. No need to call set_l2_bitmap(), this
|
|
* function doesn't support images with subclusters.
|
|
*/
|
|
set_l2_entry(s, l2_slice, j, 0);
|
|
l2_dirty = true;
|
|
continue;
|
|
}
|
|
|
|
offset = qcow2_alloc_clusters(bs, s->cluster_size);
|
|
if (offset < 0) {
|
|
ret = offset;
|
|
goto fail;
|
|
}
|
|
|
|
/* The offset must fit in the offset field */
|
|
assert((offset & L2E_OFFSET_MASK) == offset);
|
|
|
|
if (l2_refcount > 1) {
|
|
/* For shared L2 tables, set the refcount accordingly
|
|
* (it is already 1 and needs to be l2_refcount) */
|
|
ret = qcow2_update_cluster_refcount(
|
|
bs, offset >> s->cluster_bits,
|
|
refcount_diff(1, l2_refcount), false,
|
|
QCOW2_DISCARD_OTHER);
|
|
if (ret < 0) {
|
|
qcow2_free_clusters(bs, offset, s->cluster_size,
|
|
QCOW2_DISCARD_OTHER);
|
|
goto fail;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (offset_into_cluster(s, offset)) {
|
|
int l2_index = slice * s->l2_slice_size + j;
|
|
qcow2_signal_corruption(
|
|
bs, true, -1, -1,
|
|
"Cluster allocation offset "
|
|
"%#" PRIx64 " unaligned (L2 offset: %#"
|
|
PRIx64 ", L2 index: %#x)", offset,
|
|
l2_offset, l2_index);
|
|
if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
|
|
qcow2_free_clusters(bs, offset, s->cluster_size,
|
|
QCOW2_DISCARD_ALWAYS);
|
|
}
|
|
ret = -EIO;
|
|
goto fail;
|
|
}
|
|
|
|
ret = qcow2_pre_write_overlap_check(bs, 0, offset,
|
|
s->cluster_size, true);
|
|
if (ret < 0) {
|
|
if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
|
|
qcow2_free_clusters(bs, offset, s->cluster_size,
|
|
QCOW2_DISCARD_ALWAYS);
|
|
}
|
|
goto fail;
|
|
}
|
|
|
|
ret = bdrv_pwrite_zeroes(s->data_file, offset,
|
|
s->cluster_size, 0);
|
|
if (ret < 0) {
|
|
if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN) {
|
|
qcow2_free_clusters(bs, offset, s->cluster_size,
|
|
QCOW2_DISCARD_ALWAYS);
|
|
}
|
|
goto fail;
|
|
}
|
|
|
|
if (l2_refcount == 1) {
|
|
set_l2_entry(s, l2_slice, j, offset | QCOW_OFLAG_COPIED);
|
|
} else {
|
|
set_l2_entry(s, l2_slice, j, offset);
|
|
}
|
|
/*
|
|
* No need to call set_l2_bitmap() after set_l2_entry() because
|
|
* this function doesn't support images with subclusters.
|
|
*/
|
|
l2_dirty = true;
|
|
}
|
|
|
|
if (is_active_l1) {
|
|
if (l2_dirty) {
|
|
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
|
|
qcow2_cache_depends_on_flush(s->l2_table_cache);
|
|
}
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
} else {
|
|
if (l2_dirty) {
|
|
ret = qcow2_pre_write_overlap_check(
|
|
bs, QCOW2_OL_INACTIVE_L2 | QCOW2_OL_ACTIVE_L2,
|
|
slice_offset, slice_size2, false);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
ret = bdrv_pwrite(bs->file, slice_offset, slice_size2,
|
|
l2_slice, 0);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
(*visited_l1_entries)++;
|
|
if (status_cb) {
|
|
status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque);
|
|
}
|
|
}
|
|
|
|
ret = 0;
|
|
|
|
fail:
|
|
if (l2_slice) {
|
|
if (!is_active_l1) {
|
|
qemu_vfree(l2_slice);
|
|
} else {
|
|
qcow2_cache_put(s->l2_table_cache, (void **) &l2_slice);
|
|
}
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* For backed images, expands all zero clusters on the image. For non-backed
|
|
* images, deallocates all non-pre-allocated zero clusters (and claims the
|
|
* allocation for pre-allocated ones). This is important for downgrading to a
|
|
* qcow2 version which doesn't yet support metadata zero clusters.
|
|
*/
|
|
int qcow2_expand_zero_clusters(BlockDriverState *bs,
|
|
BlockDriverAmendStatusCB *status_cb,
|
|
void *cb_opaque)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
uint64_t *l1_table = NULL;
|
|
int64_t l1_entries = 0, visited_l1_entries = 0;
|
|
int ret;
|
|
int i, j;
|
|
|
|
if (status_cb) {
|
|
l1_entries = s->l1_size;
|
|
for (i = 0; i < s->nb_snapshots; i++) {
|
|
l1_entries += s->snapshots[i].l1_size;
|
|
}
|
|
}
|
|
|
|
ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size,
|
|
&visited_l1_entries, l1_entries,
|
|
status_cb, cb_opaque);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
/* Inactive L1 tables may point to active L2 tables - therefore it is
|
|
* necessary to flush the L2 table cache before trying to access the L2
|
|
* tables pointed to by inactive L1 entries (else we might try to expand
|
|
* zero clusters that have already been expanded); furthermore, it is also
|
|
* necessary to empty the L2 table cache, since it may contain tables which
|
|
* are now going to be modified directly on disk, bypassing the cache.
|
|
* qcow2_cache_empty() does both for us. */
|
|
ret = qcow2_cache_empty(bs, s->l2_table_cache);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
for (i = 0; i < s->nb_snapshots; i++) {
|
|
int l1_size2;
|
|
uint64_t *new_l1_table;
|
|
Error *local_err = NULL;
|
|
|
|
ret = qcow2_validate_table(bs, s->snapshots[i].l1_table_offset,
|
|
s->snapshots[i].l1_size, L1E_SIZE,
|
|
QCOW_MAX_L1_SIZE, "Snapshot L1 table",
|
|
&local_err);
|
|
if (ret < 0) {
|
|
error_report_err(local_err);
|
|
goto fail;
|
|
}
|
|
|
|
l1_size2 = s->snapshots[i].l1_size * L1E_SIZE;
|
|
new_l1_table = g_try_realloc(l1_table, l1_size2);
|
|
|
|
if (!new_l1_table) {
|
|
ret = -ENOMEM;
|
|
goto fail;
|
|
}
|
|
|
|
l1_table = new_l1_table;
|
|
|
|
ret = bdrv_pread(bs->file, s->snapshots[i].l1_table_offset, l1_size2,
|
|
l1_table, 0);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
for (j = 0; j < s->snapshots[i].l1_size; j++) {
|
|
be64_to_cpus(&l1_table[j]);
|
|
}
|
|
|
|
ret = expand_zero_clusters_in_l1(bs, l1_table, s->snapshots[i].l1_size,
|
|
&visited_l1_entries, l1_entries,
|
|
status_cb, cb_opaque);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
}
|
|
|
|
ret = 0;
|
|
|
|
fail:
|
|
g_free(l1_table);
|
|
return ret;
|
|
}
|
|
|
|
void qcow2_parse_compressed_l2_entry(BlockDriverState *bs, uint64_t l2_entry,
|
|
uint64_t *coffset, int *csize)
|
|
{
|
|
BDRVQcow2State *s = bs->opaque;
|
|
int nb_csectors;
|
|
|
|
assert(qcow2_get_cluster_type(bs, l2_entry) == QCOW2_CLUSTER_COMPRESSED);
|
|
|
|
*coffset = l2_entry & s->cluster_offset_mask;
|
|
|
|
nb_csectors = ((l2_entry >> s->csize_shift) & s->csize_mask) + 1;
|
|
*csize = nb_csectors * QCOW2_COMPRESSED_SECTOR_SIZE -
|
|
(*coffset & (QCOW2_COMPRESSED_SECTOR_SIZE - 1));
|
|
}
|