1500 lines
45 KiB
C
1500 lines
45 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 <zlib.h>
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#include "qemu-common.h"
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#include "block/block_int.h"
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#include "block/qcow2.h"
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#include "trace.h"
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int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
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bool exact_size)
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{
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BDRVQcowState *s = bs->opaque;
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int new_l1_size2, ret, i;
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uint64_t *new_l1_table;
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int64_t new_l1_table_offset, new_l1_size;
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uint8_t data[12];
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if (min_size <= s->l1_size)
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return 0;
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if (exact_size) {
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new_l1_size = min_size;
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} else {
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/* Bump size up to reduce the number of times we have to grow */
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new_l1_size = s->l1_size;
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if (new_l1_size == 0) {
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new_l1_size = 1;
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}
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while (min_size > new_l1_size) {
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new_l1_size = (new_l1_size * 3 + 1) / 2;
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}
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}
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if (new_l1_size > INT_MAX) {
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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 = sizeof(uint64_t) * new_l1_size;
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new_l1_table = g_malloc0(align_offset(new_l1_size2, 512));
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memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t));
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/* write new table (align to cluster) */
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BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ALLOC_TABLE);
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new_l1_table_offset = qcow2_alloc_clusters(bs, new_l1_size2);
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if (new_l1_table_offset < 0) {
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g_free(new_l1_table);
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return new_l1_table_offset;
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}
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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, QCOW2_OL_DEFAULT,
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new_l1_table_offset, new_l1_size2);
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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_table, new_l1_size2);
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if (ret < 0)
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goto fail;
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for(i = 0; i < s->l1_size; i++)
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new_l1_table[i] = be64_to_cpu(new_l1_table[i]);
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/* set new table */
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BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ACTIVATE_TABLE);
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cpu_to_be32w((uint32_t*)data, new_l1_size);
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cpu_to_be64wu((uint64_t*)(data + 4), new_l1_table_offset);
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ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, l1_size), data,sizeof(data));
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if (ret < 0) {
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goto fail;
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}
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g_free(s->l1_table);
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qcow2_free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t),
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QCOW2_DISCARD_OTHER);
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s->l1_table_offset = new_l1_table_offset;
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s->l1_table = new_l1_table;
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s->l1_size = new_l1_size;
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return 0;
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fail:
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g_free(new_l1_table);
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qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2,
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QCOW2_DISCARD_OTHER);
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return ret;
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}
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/*
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* l2_load
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*
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* Loads a L2 table into memory. If the table is in the cache, the cache
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* is used; otherwise the L2 table is loaded from the image file.
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*
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* Returns a pointer to the L2 table on success, or NULL if the read from
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* the image file failed.
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*/
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static int l2_load(BlockDriverState *bs, uint64_t l2_offset,
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uint64_t **l2_table)
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{
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BDRVQcowState *s = bs->opaque;
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int ret;
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ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, (void**) l2_table);
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return ret;
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}
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/*
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* Writes one sector of the L1 table to the disk (can't update single entries
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* and we really don't want bdrv_pread to perform a read-modify-write)
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*/
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#define L1_ENTRIES_PER_SECTOR (512 / 8)
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static int write_l1_entry(BlockDriverState *bs, int l1_index)
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{
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BDRVQcowState *s = bs->opaque;
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uint64_t buf[L1_ENTRIES_PER_SECTOR];
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int l1_start_index;
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int i, ret;
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l1_start_index = l1_index & ~(L1_ENTRIES_PER_SECTOR - 1);
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for (i = 0; i < L1_ENTRIES_PER_SECTOR; i++) {
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buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]);
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}
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ret = qcow2_pre_write_overlap_check(bs,
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QCOW2_OL_DEFAULT & ~QCOW2_OL_ACTIVE_L1,
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s->l1_table_offset + 8 * l1_start_index, sizeof(buf));
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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, s->l1_table_offset + 8 * l1_start_index,
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buf, sizeof(buf));
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if (ret < 0) {
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return ret;
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}
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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, uint64_t **table)
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{
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BDRVQcowState *s = bs->opaque;
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uint64_t old_l2_offset;
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uint64_t *l2_table;
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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 * sizeof(uint64_t));
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if (l2_offset < 0) {
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return l2_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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/* allocate a new entry in the l2 cache */
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trace_qcow2_l2_allocate_get_empty(bs, l1_index);
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ret = qcow2_cache_get_empty(bs, s->l2_table_cache, l2_offset, (void**) table);
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if (ret < 0) {
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return ret;
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}
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l2_table = *table;
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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 table */
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memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
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} else {
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uint64_t* old_table;
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/* if there was an old l2 table, read it from the disk */
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BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ);
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ret = qcow2_cache_get(bs, s->l2_table_cache,
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old_l2_offset & L1E_OFFSET_MASK,
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(void**) &old_table);
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if (ret < 0) {
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goto fail;
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}
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memcpy(l2_table, old_table, s->cluster_size);
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ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &old_table);
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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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/* write the l2 table 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_table);
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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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/* 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 = 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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*table = l2_table;
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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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qcow2_cache_put(bs, s->l2_table_cache, (void**) table);
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s->l1_table[l1_index] = old_l2_offset;
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return ret;
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}
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/*
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* Checks how many clusters in a given L2 table are contiguous in the image
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* file. As soon as one of the flags in the bitmask stop_flags changes compared
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* to the first cluster, the search is stopped and the cluster is not counted
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* as contiguous. (This allows it, for example, to stop at the first compressed
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* cluster which may require a different handling)
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*/
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static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size,
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uint64_t *l2_table, uint64_t start, uint64_t stop_flags)
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{
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int i;
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uint64_t mask = stop_flags | L2E_OFFSET_MASK;
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uint64_t offset = be64_to_cpu(l2_table[0]) & mask;
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if (!offset)
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return 0;
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for (i = start; i < start + nb_clusters; i++) {
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uint64_t l2_entry = be64_to_cpu(l2_table[i]) & mask;
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if (offset + (uint64_t) i * cluster_size != l2_entry) {
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break;
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}
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}
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return (i - start);
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}
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static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t *l2_table)
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{
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int i;
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for (i = 0; i < nb_clusters; i++) {
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int type = qcow2_get_cluster_type(be64_to_cpu(l2_table[i]));
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if (type != QCOW2_CLUSTER_UNALLOCATED) {
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break;
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}
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}
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return i;
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}
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/* The crypt function is compatible with the linux cryptoloop
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algorithm for < 4 GB images. NOTE: out_buf == in_buf is
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supported */
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void qcow2_encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
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uint8_t *out_buf, const uint8_t *in_buf,
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int nb_sectors, int enc,
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const AES_KEY *key)
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{
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union {
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uint64_t ll[2];
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uint8_t b[16];
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} ivec;
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int i;
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for(i = 0; i < nb_sectors; i++) {
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ivec.ll[0] = cpu_to_le64(sector_num);
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ivec.ll[1] = 0;
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AES_cbc_encrypt(in_buf, out_buf, 512, key,
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ivec.b, enc);
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sector_num++;
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in_buf += 512;
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out_buf += 512;
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}
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}
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static int coroutine_fn copy_sectors(BlockDriverState *bs,
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uint64_t start_sect,
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uint64_t cluster_offset,
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int n_start, int n_end)
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{
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BDRVQcowState *s = bs->opaque;
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QEMUIOVector qiov;
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struct iovec iov;
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int n, ret;
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/*
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* If this is the last cluster and it is only partially used, we must only
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* copy until the end of the image, or bdrv_check_request will fail for the
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* bdrv_read/write calls below.
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*/
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if (start_sect + n_end > bs->total_sectors) {
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n_end = bs->total_sectors - start_sect;
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}
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n = n_end - n_start;
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if (n <= 0) {
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return 0;
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}
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iov.iov_len = n * BDRV_SECTOR_SIZE;
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iov.iov_base = qemu_blockalign(bs, iov.iov_len);
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qemu_iovec_init_external(&qiov, &iov, 1);
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BLKDBG_EVENT(bs->file, BLKDBG_COW_READ);
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/* Call .bdrv_co_readv() directly instead of using the public block-layer
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* interface. This avoids double I/O throttling and request tracking,
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* which can lead to deadlock when block layer copy-on-read is enabled.
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*/
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ret = bs->drv->bdrv_co_readv(bs, start_sect + n_start, n, &qiov);
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if (ret < 0) {
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goto out;
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}
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if (s->crypt_method) {
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qcow2_encrypt_sectors(s, start_sect + n_start,
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iov.iov_base, iov.iov_base, n, 1,
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&s->aes_encrypt_key);
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}
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ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
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cluster_offset + n_start * BDRV_SECTOR_SIZE, n * BDRV_SECTOR_SIZE);
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if (ret < 0) {
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goto out;
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}
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BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE);
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ret = bdrv_co_writev(bs->file, (cluster_offset >> 9) + n_start, n, &qiov);
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if (ret < 0) {
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goto out;
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}
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ret = 0;
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out:
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qemu_vfree(iov.iov_base);
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return ret;
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}
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/*
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* get_cluster_offset
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*
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* For a given offset of the disk image, find the cluster offset in
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* qcow2 file. The offset is stored in *cluster_offset.
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*
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* on entry, *num is the number of contiguous sectors we'd like to
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* access following offset.
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*
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* on exit, *num is the number of contiguous sectors we can read.
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*
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* Returns the cluster type (QCOW2_CLUSTER_*) on success, -errno in error
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* cases.
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*/
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int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
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int *num, uint64_t *cluster_offset)
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{
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BDRVQcowState *s = bs->opaque;
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unsigned int l2_index;
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uint64_t l1_index, l2_offset, *l2_table;
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int l1_bits, c;
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unsigned int index_in_cluster, nb_clusters;
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uint64_t nb_available, nb_needed;
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int ret;
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index_in_cluster = (offset >> 9) & (s->cluster_sectors - 1);
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nb_needed = *num + index_in_cluster;
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l1_bits = s->l2_bits + s->cluster_bits;
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/* compute how many bytes there are between the offset and
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* the end of the l1 entry
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*/
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nb_available = (1ULL << l1_bits) - (offset & ((1ULL << l1_bits) - 1));
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/* compute the number of available sectors */
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nb_available = (nb_available >> 9) + index_in_cluster;
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if (nb_needed > nb_available) {
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nb_needed = nb_available;
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}
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*cluster_offset = 0;
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/* seek the the l2 offset in the l1 table */
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l1_index = offset >> l1_bits;
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if (l1_index >= s->l1_size) {
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ret = QCOW2_CLUSTER_UNALLOCATED;
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goto out;
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}
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l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
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if (!l2_offset) {
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ret = QCOW2_CLUSTER_UNALLOCATED;
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goto out;
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}
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/* load the l2 table in memory */
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ret = l2_load(bs, l2_offset, &l2_table);
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if (ret < 0) {
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return ret;
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}
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/* find the cluster offset for the given disk offset */
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l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
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*cluster_offset = be64_to_cpu(l2_table[l2_index]);
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nb_clusters = size_to_clusters(s, nb_needed << 9);
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ret = qcow2_get_cluster_type(*cluster_offset);
|
|
switch (ret) {
|
|
case QCOW2_CLUSTER_COMPRESSED:
|
|
/* Compressed clusters can only be processed one by one */
|
|
c = 1;
|
|
*cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK;
|
|
break;
|
|
case QCOW2_CLUSTER_ZERO:
|
|
if (s->qcow_version < 3) {
|
|
return -EIO;
|
|
}
|
|
c = count_contiguous_clusters(nb_clusters, s->cluster_size,
|
|
&l2_table[l2_index], 0,
|
|
QCOW_OFLAG_COMPRESSED | QCOW_OFLAG_ZERO);
|
|
*cluster_offset = 0;
|
|
break;
|
|
case QCOW2_CLUSTER_UNALLOCATED:
|
|
/* how many empty clusters ? */
|
|
c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]);
|
|
*cluster_offset = 0;
|
|
break;
|
|
case QCOW2_CLUSTER_NORMAL:
|
|
/* how many allocated clusters ? */
|
|
c = count_contiguous_clusters(nb_clusters, s->cluster_size,
|
|
&l2_table[l2_index], 0,
|
|
QCOW_OFLAG_COMPRESSED | QCOW_OFLAG_ZERO);
|
|
*cluster_offset &= L2E_OFFSET_MASK;
|
|
break;
|
|
default:
|
|
abort();
|
|
}
|
|
|
|
qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
|
|
|
nb_available = (c * s->cluster_sectors);
|
|
|
|
out:
|
|
if (nb_available > nb_needed)
|
|
nb_available = nb_needed;
|
|
|
|
*num = nb_available - index_in_cluster;
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* get_cluster_table
|
|
*
|
|
* for a given disk offset, load (and allocate if needed)
|
|
* the l2 table.
|
|
*
|
|
* the l2 table offset in the qcow2 file and the cluster index
|
|
* in the l2 table are given to the caller.
|
|
*
|
|
* Returns 0 on success, -errno in failure case
|
|
*/
|
|
static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
|
|
uint64_t **new_l2_table,
|
|
int *new_l2_index)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
unsigned int l2_index;
|
|
uint64_t l1_index, l2_offset;
|
|
uint64_t *l2_table = NULL;
|
|
int ret;
|
|
|
|
/* seek the the l2 offset in the l1 table */
|
|
|
|
l1_index = offset >> (s->l2_bits + s->cluster_bits);
|
|
if (l1_index >= s->l1_size) {
|
|
ret = qcow2_grow_l1_table(bs, l1_index + 1, false);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
assert(l1_index < s->l1_size);
|
|
l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
|
|
|
|
/* seek the l2 table of the given l2 offset */
|
|
|
|
if (s->l1_table[l1_index] & QCOW_OFLAG_COPIED) {
|
|
/* load the l2 table in memory */
|
|
ret = l2_load(bs, l2_offset, &l2_table);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
} else {
|
|
/* First allocate a new L2 table (and do COW if needed) */
|
|
ret = l2_allocate(bs, l1_index, &l2_table);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
/* Then decrease the refcount of the old table */
|
|
if (l2_offset) {
|
|
qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
|
|
QCOW2_DISCARD_OTHER);
|
|
}
|
|
}
|
|
|
|
/* find the cluster offset for the given disk offset */
|
|
|
|
l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
|
|
|
|
*new_l2_table = l2_table;
|
|
*new_l2_index = l2_index;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* alloc_compressed_cluster_offset
|
|
*
|
|
* For a given offset of the disk image, return cluster offset in
|
|
* qcow2 file.
|
|
*
|
|
* If the offset is not found, allocate a new compressed cluster.
|
|
*
|
|
* Return the cluster offset if successful,
|
|
* Return 0, otherwise.
|
|
*
|
|
*/
|
|
|
|
uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
|
|
uint64_t offset,
|
|
int compressed_size)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
int l2_index, ret;
|
|
uint64_t *l2_table;
|
|
int64_t cluster_offset;
|
|
int nb_csectors;
|
|
|
|
ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
|
|
if (ret < 0) {
|
|
return 0;
|
|
}
|
|
|
|
/* Compression can't overwrite anything. Fail if the cluster was already
|
|
* allocated. */
|
|
cluster_offset = be64_to_cpu(l2_table[l2_index]);
|
|
if (cluster_offset & L2E_OFFSET_MASK) {
|
|
qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
|
return 0;
|
|
}
|
|
|
|
cluster_offset = qcow2_alloc_bytes(bs, compressed_size);
|
|
if (cluster_offset < 0) {
|
|
qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
|
return 0;
|
|
}
|
|
|
|
nb_csectors = ((cluster_offset + compressed_size - 1) >> 9) -
|
|
(cluster_offset >> 9);
|
|
|
|
cluster_offset |= QCOW_OFLAG_COMPRESSED |
|
|
((uint64_t)nb_csectors << s->csize_shift);
|
|
|
|
/* update L2 table */
|
|
|
|
/* compressed clusters never have the copied flag */
|
|
|
|
BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED);
|
|
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
|
|
l2_table[l2_index] = cpu_to_be64(cluster_offset);
|
|
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
|
if (ret < 0) {
|
|
return 0;
|
|
}
|
|
|
|
return cluster_offset;
|
|
}
|
|
|
|
static int perform_cow(BlockDriverState *bs, QCowL2Meta *m, Qcow2COWRegion *r)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
int ret;
|
|
|
|
if (r->nb_sectors == 0) {
|
|
return 0;
|
|
}
|
|
|
|
qemu_co_mutex_unlock(&s->lock);
|
|
ret = copy_sectors(bs, m->offset / BDRV_SECTOR_SIZE, m->alloc_offset,
|
|
r->offset / BDRV_SECTOR_SIZE,
|
|
r->offset / BDRV_SECTOR_SIZE + r->nb_sectors);
|
|
qemu_co_mutex_lock(&s->lock);
|
|
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Before we update the L2 table to actually point to the new cluster, we
|
|
* need to be sure that the refcounts have been increased and COW was
|
|
* handled.
|
|
*/
|
|
qcow2_cache_depends_on_flush(s->l2_table_cache);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
int i, j = 0, l2_index, ret;
|
|
uint64_t *old_cluster, *l2_table;
|
|
uint64_t cluster_offset = m->alloc_offset;
|
|
|
|
trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters);
|
|
assert(m->nb_clusters > 0);
|
|
|
|
old_cluster = g_malloc(m->nb_clusters * sizeof(uint64_t));
|
|
|
|
/* copy content of unmodified sectors */
|
|
ret = perform_cow(bs, m, &m->cow_start);
|
|
if (ret < 0) {
|
|
goto err;
|
|
}
|
|
|
|
ret = perform_cow(bs, m, &m->cow_end);
|
|
if (ret < 0) {
|
|
goto err;
|
|
}
|
|
|
|
/* Update L2 table. */
|
|
if (s->use_lazy_refcounts) {
|
|
qcow2_mark_dirty(bs);
|
|
}
|
|
if (qcow2_need_accurate_refcounts(s)) {
|
|
qcow2_cache_set_dependency(bs, s->l2_table_cache,
|
|
s->refcount_block_cache);
|
|
}
|
|
|
|
ret = get_cluster_table(bs, m->offset, &l2_table, &l2_index);
|
|
if (ret < 0) {
|
|
goto err;
|
|
}
|
|
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
|
|
|
|
for (i = 0; i < m->nb_clusters; i++) {
|
|
/* if two concurrent writes happen to the same unallocated cluster
|
|
* each write allocates separate cluster and writes data concurrently.
|
|
* The first one to complete updates l2 table with pointer to its
|
|
* cluster the second one has to do RMW (which is done above by
|
|
* copy_sectors()), update l2 table with its cluster pointer and free
|
|
* old cluster. This is what this loop does */
|
|
if(l2_table[l2_index + i] != 0)
|
|
old_cluster[j++] = l2_table[l2_index + i];
|
|
|
|
l2_table[l2_index + i] = cpu_to_be64((cluster_offset +
|
|
(i << s->cluster_bits)) | QCOW_OFLAG_COPIED);
|
|
}
|
|
|
|
|
|
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
|
if (ret < 0) {
|
|
goto err;
|
|
}
|
|
|
|
/*
|
|
* If this was a COW, we need to decrease the refcount of the old cluster.
|
|
* Also flush bs->file to get the right order for L2 and refcount update.
|
|
*
|
|
* Don't discard clusters that reach a refcount of 0 (e.g. compressed
|
|
* clusters), the next write will reuse them anyway.
|
|
*/
|
|
if (j != 0) {
|
|
for (i = 0; i < j; i++) {
|
|
qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1,
|
|
QCOW2_DISCARD_NEVER);
|
|
}
|
|
}
|
|
|
|
ret = 0;
|
|
err:
|
|
g_free(old_cluster);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Returns the number of contiguous clusters that can be used for an allocating
|
|
* write, but require COW to be performed (this includes yet unallocated space,
|
|
* which must copy from the backing file)
|
|
*/
|
|
static int count_cow_clusters(BDRVQcowState *s, int nb_clusters,
|
|
uint64_t *l2_table, int l2_index)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < nb_clusters; i++) {
|
|
uint64_t l2_entry = be64_to_cpu(l2_table[l2_index + i]);
|
|
int cluster_type = qcow2_get_cluster_type(l2_entry);
|
|
|
|
switch(cluster_type) {
|
|
case QCOW2_CLUSTER_NORMAL:
|
|
if (l2_entry & QCOW_OFLAG_COPIED) {
|
|
goto out;
|
|
}
|
|
break;
|
|
case QCOW2_CLUSTER_UNALLOCATED:
|
|
case QCOW2_CLUSTER_COMPRESSED:
|
|
case QCOW2_CLUSTER_ZERO:
|
|
break;
|
|
default:
|
|
abort();
|
|
}
|
|
}
|
|
|
|
out:
|
|
assert(i <= nb_clusters);
|
|
return i;
|
|
}
|
|
|
|
/*
|
|
* Check if there already is an AIO write request in flight which allocates
|
|
* the same cluster. In this case we need to wait until the previous
|
|
* request has completed and updated the L2 table accordingly.
|
|
*
|
|
* Returns:
|
|
* 0 if there was no dependency. *cur_bytes indicates the number of
|
|
* bytes from guest_offset that can be read before the next
|
|
* dependency must be processed (or the request is complete)
|
|
*
|
|
* -EAGAIN if we had to wait for another request, previously gathered
|
|
* information on cluster allocation may be invalid now. The caller
|
|
* must start over anyway, so consider *cur_bytes undefined.
|
|
*/
|
|
static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset,
|
|
uint64_t *cur_bytes, QCowL2Meta **m)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
QCowL2Meta *old_alloc;
|
|
uint64_t bytes = *cur_bytes;
|
|
|
|
QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) {
|
|
|
|
uint64_t start = guest_offset;
|
|
uint64_t end = start + bytes;
|
|
uint64_t old_start = l2meta_cow_start(old_alloc);
|
|
uint64_t old_end = l2meta_cow_end(old_alloc);
|
|
|
|
if (end <= old_start || start >= old_end) {
|
|
/* No intersection */
|
|
} else {
|
|
if (start < old_start) {
|
|
/* Stop at the start of a running allocation */
|
|
bytes = old_start - start;
|
|
} else {
|
|
bytes = 0;
|
|
}
|
|
|
|
/* Stop if already an l2meta exists. After yielding, it wouldn't
|
|
* be valid any more, so we'd have to clean up the old L2Metas
|
|
* and deal with requests depending on them before starting to
|
|
* gather new ones. Not worth the trouble. */
|
|
if (bytes == 0 && *m) {
|
|
*cur_bytes = 0;
|
|
return 0;
|
|
}
|
|
|
|
if (bytes == 0) {
|
|
/* Wait for the dependency to complete. We need to recheck
|
|
* the free/allocated clusters when we continue. */
|
|
qemu_co_mutex_unlock(&s->lock);
|
|
qemu_co_queue_wait(&old_alloc->dependent_requests);
|
|
qemu_co_mutex_lock(&s->lock);
|
|
return -EAGAIN;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Make sure that existing clusters and new allocations are only used up to
|
|
* the next dependency if we shortened the request above */
|
|
*cur_bytes = bytes;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Checks how many already allocated clusters that don't require a copy on
|
|
* write there are at the given guest_offset (up to *bytes). If
|
|
* *host_offset is not zero, only physically contiguous clusters beginning at
|
|
* this host offset are counted.
|
|
*
|
|
* Note that guest_offset may not be cluster aligned. In this case, the
|
|
* returned *host_offset points to exact byte referenced by guest_offset and
|
|
* therefore isn't cluster aligned as well.
|
|
*
|
|
* Returns:
|
|
* 0: if no allocated clusters are available at the given offset.
|
|
* *bytes is normally unchanged. It is set to 0 if the cluster
|
|
* is allocated and doesn't need COW, but doesn't have the right
|
|
* physical offset.
|
|
*
|
|
* 1: if allocated clusters that don't require a COW are available at
|
|
* the requested offset. *bytes may have decreased and describes
|
|
* the length of the area that can be written to.
|
|
*
|
|
* -errno: in error cases
|
|
*/
|
|
static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
|
|
uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
int l2_index;
|
|
uint64_t cluster_offset;
|
|
uint64_t *l2_table;
|
|
unsigned int nb_clusters;
|
|
unsigned int keep_clusters;
|
|
int ret, pret;
|
|
|
|
trace_qcow2_handle_copied(qemu_coroutine_self(), guest_offset, *host_offset,
|
|
*bytes);
|
|
|
|
assert(*host_offset == 0 || offset_into_cluster(s, guest_offset)
|
|
== offset_into_cluster(s, *host_offset));
|
|
|
|
/*
|
|
* Calculate the number of clusters to look for. We stop at L2 table
|
|
* boundaries to keep things simple.
|
|
*/
|
|
nb_clusters =
|
|
size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
|
|
|
|
l2_index = offset_to_l2_index(s, guest_offset);
|
|
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
|
|
|
|
/* Find L2 entry for the first involved cluster */
|
|
ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
cluster_offset = be64_to_cpu(l2_table[l2_index]);
|
|
|
|
/* Check how many clusters are already allocated and don't need COW */
|
|
if (qcow2_get_cluster_type(cluster_offset) == QCOW2_CLUSTER_NORMAL
|
|
&& (cluster_offset & QCOW_OFLAG_COPIED))
|
|
{
|
|
/* If a specific host_offset is required, check it */
|
|
bool offset_matches =
|
|
(cluster_offset & L2E_OFFSET_MASK) == *host_offset;
|
|
|
|
if (*host_offset != 0 && !offset_matches) {
|
|
*bytes = 0;
|
|
ret = 0;
|
|
goto out;
|
|
}
|
|
|
|
/* We keep all QCOW_OFLAG_COPIED clusters */
|
|
keep_clusters =
|
|
count_contiguous_clusters(nb_clusters, s->cluster_size,
|
|
&l2_table[l2_index], 0,
|
|
QCOW_OFLAG_COPIED | QCOW_OFLAG_ZERO);
|
|
assert(keep_clusters <= nb_clusters);
|
|
|
|
*bytes = MIN(*bytes,
|
|
keep_clusters * s->cluster_size
|
|
- offset_into_cluster(s, guest_offset));
|
|
|
|
ret = 1;
|
|
} else {
|
|
ret = 0;
|
|
}
|
|
|
|
/* Cleanup */
|
|
out:
|
|
pret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
|
if (pret < 0) {
|
|
return pret;
|
|
}
|
|
|
|
/* Only return a host offset if we actually made progress. Otherwise we
|
|
* would make requirements for handle_alloc() that it can't fulfill */
|
|
if (ret) {
|
|
*host_offset = (cluster_offset & L2E_OFFSET_MASK)
|
|
+ offset_into_cluster(s, guest_offset);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Allocates new clusters for the given guest_offset.
|
|
*
|
|
* At most *nb_clusters are allocated, and on return *nb_clusters is updated to
|
|
* contain the number of clusters that have been allocated and are contiguous
|
|
* in the image file.
|
|
*
|
|
* If *host_offset is non-zero, it specifies the offset in the image file at
|
|
* which the new clusters must start. *nb_clusters can be 0 on return in this
|
|
* case if the cluster at host_offset is already in use. If *host_offset is
|
|
* zero, the clusters can be allocated anywhere in the image file.
|
|
*
|
|
* *host_offset is updated to contain the offset into the image file at which
|
|
* the first allocated cluster starts.
|
|
*
|
|
* Return 0 on success and -errno in error cases. -EAGAIN means that the
|
|
* function has been waiting for another request and the allocation must be
|
|
* restarted, but the whole request should not be failed.
|
|
*/
|
|
static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
|
|
uint64_t *host_offset, unsigned int *nb_clusters)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
|
|
trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset,
|
|
*host_offset, *nb_clusters);
|
|
|
|
/* Allocate new clusters */
|
|
trace_qcow2_cluster_alloc_phys(qemu_coroutine_self());
|
|
if (*host_offset == 0) {
|
|
int64_t cluster_offset =
|
|
qcow2_alloc_clusters(bs, *nb_clusters * s->cluster_size);
|
|
if (cluster_offset < 0) {
|
|
return cluster_offset;
|
|
}
|
|
*host_offset = cluster_offset;
|
|
return 0;
|
|
} else {
|
|
int ret = qcow2_alloc_clusters_at(bs, *host_offset, *nb_clusters);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
*nb_clusters = ret;
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Allocates new clusters for an area that either is yet unallocated or needs a
|
|
* copy on write. If *host_offset is non-zero, clusters are only allocated if
|
|
* the new allocation can match the specified host offset.
|
|
*
|
|
* Note that guest_offset may not be cluster aligned. In this case, the
|
|
* returned *host_offset points to exact byte referenced by guest_offset and
|
|
* therefore isn't cluster aligned as well.
|
|
*
|
|
* Returns:
|
|
* 0: if no clusters could be allocated. *bytes is set to 0,
|
|
* *host_offset is left unchanged.
|
|
*
|
|
* 1: if new clusters were allocated. *bytes may be decreased if the
|
|
* new allocation doesn't cover all of the requested area.
|
|
* *host_offset is updated to contain the host offset of the first
|
|
* newly allocated cluster.
|
|
*
|
|
* -errno: in error cases
|
|
*/
|
|
static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
|
|
uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
int l2_index;
|
|
uint64_t *l2_table;
|
|
uint64_t entry;
|
|
unsigned int nb_clusters;
|
|
int ret;
|
|
|
|
uint64_t alloc_cluster_offset;
|
|
|
|
trace_qcow2_handle_alloc(qemu_coroutine_self(), guest_offset, *host_offset,
|
|
*bytes);
|
|
assert(*bytes > 0);
|
|
|
|
/*
|
|
* Calculate the number of clusters to look for. We stop at L2 table
|
|
* boundaries to keep things simple.
|
|
*/
|
|
nb_clusters =
|
|
size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
|
|
|
|
l2_index = offset_to_l2_index(s, guest_offset);
|
|
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
|
|
|
|
/* Find L2 entry for the first involved cluster */
|
|
ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
entry = be64_to_cpu(l2_table[l2_index]);
|
|
|
|
/* For the moment, overwrite compressed clusters one by one */
|
|
if (entry & QCOW_OFLAG_COMPRESSED) {
|
|
nb_clusters = 1;
|
|
} else {
|
|
nb_clusters = count_cow_clusters(s, nb_clusters, l2_table, l2_index);
|
|
}
|
|
|
|
/* This function is only called when there were no non-COW clusters, so if
|
|
* we can't find any unallocated or COW clusters either, something is
|
|
* wrong with our code. */
|
|
assert(nb_clusters > 0);
|
|
|
|
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
/* Allocate, if necessary at a given offset in the image file */
|
|
alloc_cluster_offset = start_of_cluster(s, *host_offset);
|
|
ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset,
|
|
&nb_clusters);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
/* Can't extend contiguous allocation */
|
|
if (nb_clusters == 0) {
|
|
*bytes = 0;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Save info needed for meta data update.
|
|
*
|
|
* requested_sectors: Number of sectors from the start of the first
|
|
* newly allocated cluster to the end of the (possibly shortened
|
|
* before) write request.
|
|
*
|
|
* avail_sectors: Number of sectors from the start of the first
|
|
* newly allocated to the end of the last newly allocated cluster.
|
|
*
|
|
* nb_sectors: The number of sectors from the start of the first
|
|
* newly allocated cluster to the end of the area that the write
|
|
* request actually writes to (excluding COW at the end)
|
|
*/
|
|
int requested_sectors =
|
|
(*bytes + offset_into_cluster(s, guest_offset))
|
|
>> BDRV_SECTOR_BITS;
|
|
int avail_sectors = nb_clusters
|
|
<< (s->cluster_bits - BDRV_SECTOR_BITS);
|
|
int alloc_n_start = offset_into_cluster(s, guest_offset)
|
|
>> BDRV_SECTOR_BITS;
|
|
int nb_sectors = MIN(requested_sectors, avail_sectors);
|
|
QCowL2Meta *old_m = *m;
|
|
|
|
*m = g_malloc0(sizeof(**m));
|
|
|
|
**m = (QCowL2Meta) {
|
|
.next = old_m,
|
|
|
|
.alloc_offset = alloc_cluster_offset,
|
|
.offset = start_of_cluster(s, guest_offset),
|
|
.nb_clusters = nb_clusters,
|
|
.nb_available = nb_sectors,
|
|
|
|
.cow_start = {
|
|
.offset = 0,
|
|
.nb_sectors = alloc_n_start,
|
|
},
|
|
.cow_end = {
|
|
.offset = nb_sectors * BDRV_SECTOR_SIZE,
|
|
.nb_sectors = avail_sectors - nb_sectors,
|
|
},
|
|
};
|
|
qemu_co_queue_init(&(*m)->dependent_requests);
|
|
QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
|
|
|
|
*host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset);
|
|
*bytes = MIN(*bytes, (nb_sectors * BDRV_SECTOR_SIZE)
|
|
- offset_into_cluster(s, guest_offset));
|
|
assert(*bytes != 0);
|
|
|
|
return 1;
|
|
|
|
fail:
|
|
if (*m && (*m)->nb_clusters > 0) {
|
|
QLIST_REMOVE(*m, next_in_flight);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* alloc_cluster_offset
|
|
*
|
|
* For a given offset on the virtual disk, find the cluster offset in qcow2
|
|
* file. If the offset is not found, allocate a new cluster.
|
|
*
|
|
* If the cluster was already allocated, m->nb_clusters is set to 0 and
|
|
* other fields in m are meaningless.
|
|
*
|
|
* If the cluster is newly allocated, m->nb_clusters is set to the number of
|
|
* contiguous clusters that have been allocated. In this case, the other
|
|
* fields of m are valid and contain information about the first allocated
|
|
* cluster.
|
|
*
|
|
* If the request conflicts with another write request in flight, the coroutine
|
|
* is queued and will be reentered when the dependency has completed.
|
|
*
|
|
* Return 0 on success and -errno in error cases
|
|
*/
|
|
int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
|
|
int n_start, int n_end, int *num, uint64_t *host_offset, QCowL2Meta **m)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
uint64_t start, remaining;
|
|
uint64_t cluster_offset;
|
|
uint64_t cur_bytes;
|
|
int ret;
|
|
|
|
trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset,
|
|
n_start, n_end);
|
|
|
|
assert(n_start * BDRV_SECTOR_SIZE == offset_into_cluster(s, offset));
|
|
offset = start_of_cluster(s, offset);
|
|
|
|
again:
|
|
start = offset + (n_start << BDRV_SECTOR_BITS);
|
|
remaining = (n_end - n_start) << BDRV_SECTOR_BITS;
|
|
cluster_offset = 0;
|
|
*host_offset = 0;
|
|
cur_bytes = 0;
|
|
*m = NULL;
|
|
|
|
while (true) {
|
|
|
|
if (!*host_offset) {
|
|
*host_offset = start_of_cluster(s, cluster_offset);
|
|
}
|
|
|
|
assert(remaining >= cur_bytes);
|
|
|
|
start += cur_bytes;
|
|
remaining -= cur_bytes;
|
|
cluster_offset += cur_bytes;
|
|
|
|
if (remaining == 0) {
|
|
break;
|
|
}
|
|
|
|
cur_bytes = remaining;
|
|
|
|
/*
|
|
* Now start gathering as many contiguous clusters as possible:
|
|
*
|
|
* 1. Check for overlaps with in-flight allocations
|
|
*
|
|
* a) Overlap not in the first cluster -> shorten this request and
|
|
* let the caller handle the rest in its next loop iteration.
|
|
*
|
|
* b) Real overlaps of two requests. Yield and restart the search
|
|
* for contiguous clusters (the situation could have changed
|
|
* while we were sleeping)
|
|
*
|
|
* c) TODO: Request starts in the same cluster as the in-flight
|
|
* allocation ends. Shorten the COW of the in-fight allocation,
|
|
* set cluster_offset to write to the same cluster and set up
|
|
* the right synchronisation between the in-flight request and
|
|
* the new one.
|
|
*/
|
|
ret = handle_dependencies(bs, start, &cur_bytes, m);
|
|
if (ret == -EAGAIN) {
|
|
/* Currently handle_dependencies() doesn't yield if we already had
|
|
* an allocation. If it did, we would have to clean up the L2Meta
|
|
* structs before starting over. */
|
|
assert(*m == NULL);
|
|
goto again;
|
|
} else if (ret < 0) {
|
|
return ret;
|
|
} else if (cur_bytes == 0) {
|
|
break;
|
|
} else {
|
|
/* handle_dependencies() may have decreased cur_bytes (shortened
|
|
* the allocations below) so that the next dependency is processed
|
|
* correctly during the next loop iteration. */
|
|
}
|
|
|
|
/*
|
|
* 2. Count contiguous COPIED clusters.
|
|
*/
|
|
ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m);
|
|
if (ret < 0) {
|
|
return ret;
|
|
} else if (ret) {
|
|
continue;
|
|
} else if (cur_bytes == 0) {
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* 3. If the request still hasn't completed, allocate new clusters,
|
|
* considering any cluster_offset of steps 1c or 2.
|
|
*/
|
|
ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m);
|
|
if (ret < 0) {
|
|
return ret;
|
|
} else if (ret) {
|
|
continue;
|
|
} else {
|
|
assert(cur_bytes == 0);
|
|
break;
|
|
}
|
|
}
|
|
|
|
*num = (n_end - n_start) - (remaining >> BDRV_SECTOR_BITS);
|
|
assert(*num > 0);
|
|
assert(*host_offset != 0);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
|
|
const uint8_t *buf, int buf_size)
|
|
{
|
|
z_stream strm1, *strm = &strm1;
|
|
int ret, out_len;
|
|
|
|
memset(strm, 0, sizeof(*strm));
|
|
|
|
strm->next_in = (uint8_t *)buf;
|
|
strm->avail_in = buf_size;
|
|
strm->next_out = out_buf;
|
|
strm->avail_out = out_buf_size;
|
|
|
|
ret = inflateInit2(strm, -12);
|
|
if (ret != Z_OK)
|
|
return -1;
|
|
ret = inflate(strm, Z_FINISH);
|
|
out_len = strm->next_out - out_buf;
|
|
if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
|
|
out_len != out_buf_size) {
|
|
inflateEnd(strm);
|
|
return -1;
|
|
}
|
|
inflateEnd(strm);
|
|
return 0;
|
|
}
|
|
|
|
int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
int ret, csize, nb_csectors, sector_offset;
|
|
uint64_t coffset;
|
|
|
|
coffset = cluster_offset & s->cluster_offset_mask;
|
|
if (s->cluster_cache_offset != coffset) {
|
|
nb_csectors = ((cluster_offset >> s->csize_shift) & s->csize_mask) + 1;
|
|
sector_offset = coffset & 511;
|
|
csize = nb_csectors * 512 - sector_offset;
|
|
BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
|
|
ret = bdrv_read(bs->file, coffset >> 9, s->cluster_data, nb_csectors);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
if (decompress_buffer(s->cluster_cache, s->cluster_size,
|
|
s->cluster_data + sector_offset, csize) < 0) {
|
|
return -EIO;
|
|
}
|
|
s->cluster_cache_offset = coffset;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* This discards as many clusters of nb_clusters as possible at once (i.e.
|
|
* all clusters in the same L2 table) and returns the number of discarded
|
|
* clusters.
|
|
*/
|
|
static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
|
|
unsigned int nb_clusters)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
uint64_t *l2_table;
|
|
int l2_index;
|
|
int ret;
|
|
int i;
|
|
|
|
ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
/* Limit nb_clusters to one L2 table */
|
|
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
|
|
|
|
for (i = 0; i < nb_clusters; i++) {
|
|
uint64_t old_offset;
|
|
|
|
old_offset = be64_to_cpu(l2_table[l2_index + i]);
|
|
if ((old_offset & L2E_OFFSET_MASK) == 0) {
|
|
continue;
|
|
}
|
|
|
|
/* First remove L2 entries */
|
|
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
|
|
l2_table[l2_index + i] = cpu_to_be64(0);
|
|
|
|
/* Then decrease the refcount */
|
|
qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
|
|
}
|
|
|
|
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
return nb_clusters;
|
|
}
|
|
|
|
int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
|
|
int nb_sectors)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
uint64_t end_offset;
|
|
unsigned int nb_clusters;
|
|
int ret;
|
|
|
|
end_offset = offset + (nb_sectors << BDRV_SECTOR_BITS);
|
|
|
|
/* Round start up and end down */
|
|
offset = align_offset(offset, s->cluster_size);
|
|
end_offset &= ~(s->cluster_size - 1);
|
|
|
|
if (offset > end_offset) {
|
|
return 0;
|
|
}
|
|
|
|
nb_clusters = size_to_clusters(s, end_offset - offset);
|
|
|
|
s->cache_discards = true;
|
|
|
|
/* Each L2 table is handled by its own loop iteration */
|
|
while (nb_clusters > 0) {
|
|
ret = discard_single_l2(bs, offset, nb_clusters);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
nb_clusters -= ret;
|
|
offset += (ret * s->cluster_size);
|
|
}
|
|
|
|
ret = 0;
|
|
fail:
|
|
s->cache_discards = false;
|
|
qcow2_process_discards(bs, ret);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This zeroes as many clusters of nb_clusters as possible at once (i.e.
|
|
* all clusters in the same L2 table) and returns the number of zeroed
|
|
* clusters.
|
|
*/
|
|
static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
|
|
unsigned int nb_clusters)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
uint64_t *l2_table;
|
|
int l2_index;
|
|
int ret;
|
|
int i;
|
|
|
|
ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
/* Limit nb_clusters to one L2 table */
|
|
nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
|
|
|
|
for (i = 0; i < nb_clusters; i++) {
|
|
uint64_t old_offset;
|
|
|
|
old_offset = be64_to_cpu(l2_table[l2_index + i]);
|
|
|
|
/* Update L2 entries */
|
|
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
|
|
if (old_offset & QCOW_OFLAG_COMPRESSED) {
|
|
l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
|
|
qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
|
|
} else {
|
|
l2_table[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO);
|
|
}
|
|
}
|
|
|
|
ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
return nb_clusters;
|
|
}
|
|
|
|
int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
unsigned int nb_clusters;
|
|
int ret;
|
|
|
|
/* The zero flag is only supported by version 3 and newer */
|
|
if (s->qcow_version < 3) {
|
|
return -ENOTSUP;
|
|
}
|
|
|
|
/* Each L2 table is handled by its own loop iteration */
|
|
nb_clusters = size_to_clusters(s, nb_sectors << BDRV_SECTOR_BITS);
|
|
|
|
s->cache_discards = true;
|
|
|
|
while (nb_clusters > 0) {
|
|
ret = zero_single_l2(bs, offset, nb_clusters);
|
|
if (ret < 0) {
|
|
goto fail;
|
|
}
|
|
|
|
nb_clusters -= ret;
|
|
offset += (ret * s->cluster_size);
|
|
}
|
|
|
|
ret = 0;
|
|
fail:
|
|
s->cache_discards = false;
|
|
qcow2_process_discards(bs, ret);
|
|
|
|
return ret;
|
|
}
|