mirror of https://gitee.com/openkylin/qemu.git
324 lines
7.8 KiB
C
324 lines
7.8 KiB
C
/*
|
|
* L2/refcount table cache for the QCOW2 format
|
|
*
|
|
* Copyright (c) 2010 Kevin Wolf <kwolf@redhat.com>
|
|
*
|
|
* Permission is hereby granted, free of charge, to any person obtaining a copy
|
|
* of this software and associated documentation files (the "Software"), to deal
|
|
* in the Software without restriction, including without limitation the rights
|
|
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
|
|
* copies of the Software, and to permit persons to whom the Software is
|
|
* furnished to do so, subject to the following conditions:
|
|
*
|
|
* The above copyright notice and this permission notice shall be included in
|
|
* all copies or substantial portions of the Software.
|
|
*
|
|
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
|
|
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
|
|
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
|
|
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
|
|
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
|
|
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
|
|
* THE SOFTWARE.
|
|
*/
|
|
|
|
#include "block/block_int.h"
|
|
#include "qemu-common.h"
|
|
#include "qcow2.h"
|
|
#include "trace.h"
|
|
|
|
typedef struct Qcow2CachedTable {
|
|
void* table;
|
|
int64_t offset;
|
|
bool dirty;
|
|
int cache_hits;
|
|
int ref;
|
|
} Qcow2CachedTable;
|
|
|
|
struct Qcow2Cache {
|
|
Qcow2CachedTable* entries;
|
|
struct Qcow2Cache* depends;
|
|
int size;
|
|
bool depends_on_flush;
|
|
};
|
|
|
|
Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
Qcow2Cache *c;
|
|
int i;
|
|
|
|
c = g_malloc0(sizeof(*c));
|
|
c->size = num_tables;
|
|
c->entries = g_malloc0(sizeof(*c->entries) * num_tables);
|
|
|
|
for (i = 0; i < c->size; i++) {
|
|
c->entries[i].table = qemu_blockalign(bs, s->cluster_size);
|
|
}
|
|
|
|
return c;
|
|
}
|
|
|
|
int qcow2_cache_destroy(BlockDriverState* bs, Qcow2Cache *c)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < c->size; i++) {
|
|
assert(c->entries[i].ref == 0);
|
|
qemu_vfree(c->entries[i].table);
|
|
}
|
|
|
|
g_free(c->entries);
|
|
g_free(c);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int qcow2_cache_flush_dependency(BlockDriverState *bs, Qcow2Cache *c)
|
|
{
|
|
int ret;
|
|
|
|
ret = qcow2_cache_flush(bs, c->depends);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
c->depends = NULL;
|
|
c->depends_on_flush = false;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int qcow2_cache_entry_flush(BlockDriverState *bs, Qcow2Cache *c, int i)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
int ret = 0;
|
|
|
|
if (!c->entries[i].dirty || !c->entries[i].offset) {
|
|
return 0;
|
|
}
|
|
|
|
trace_qcow2_cache_entry_flush(qemu_coroutine_self(),
|
|
c == s->l2_table_cache, i);
|
|
|
|
if (c->depends) {
|
|
ret = qcow2_cache_flush_dependency(bs, c);
|
|
} else if (c->depends_on_flush) {
|
|
ret = bdrv_flush(bs->file);
|
|
if (ret >= 0) {
|
|
c->depends_on_flush = false;
|
|
}
|
|
}
|
|
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
if (c == s->refcount_block_cache) {
|
|
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_UPDATE_PART);
|
|
} else if (c == s->l2_table_cache) {
|
|
BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE);
|
|
}
|
|
|
|
ret = bdrv_pwrite(bs->file, c->entries[i].offset, c->entries[i].table,
|
|
s->cluster_size);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
c->entries[i].dirty = false;
|
|
|
|
return 0;
|
|
}
|
|
|
|
int qcow2_cache_flush(BlockDriverState *bs, Qcow2Cache *c)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
int result = 0;
|
|
int ret;
|
|
int i;
|
|
|
|
trace_qcow2_cache_flush(qemu_coroutine_self(), c == s->l2_table_cache);
|
|
|
|
for (i = 0; i < c->size; i++) {
|
|
ret = qcow2_cache_entry_flush(bs, c, i);
|
|
if (ret < 0 && result != -ENOSPC) {
|
|
result = ret;
|
|
}
|
|
}
|
|
|
|
if (result == 0) {
|
|
ret = bdrv_flush(bs->file);
|
|
if (ret < 0) {
|
|
result = ret;
|
|
}
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
int qcow2_cache_set_dependency(BlockDriverState *bs, Qcow2Cache *c,
|
|
Qcow2Cache *dependency)
|
|
{
|
|
int ret;
|
|
|
|
if (dependency->depends) {
|
|
ret = qcow2_cache_flush_dependency(bs, dependency);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
if (c->depends && (c->depends != dependency)) {
|
|
ret = qcow2_cache_flush_dependency(bs, c);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
c->depends = dependency;
|
|
return 0;
|
|
}
|
|
|
|
void qcow2_cache_depends_on_flush(Qcow2Cache *c)
|
|
{
|
|
c->depends_on_flush = true;
|
|
}
|
|
|
|
static int qcow2_cache_find_entry_to_replace(Qcow2Cache *c)
|
|
{
|
|
int i;
|
|
int min_count = INT_MAX;
|
|
int min_index = -1;
|
|
|
|
|
|
for (i = 0; i < c->size; i++) {
|
|
if (c->entries[i].ref) {
|
|
continue;
|
|
}
|
|
|
|
if (c->entries[i].cache_hits < min_count) {
|
|
min_index = i;
|
|
min_count = c->entries[i].cache_hits;
|
|
}
|
|
|
|
/* Give newer hits priority */
|
|
/* TODO Check how to optimize the replacement strategy */
|
|
c->entries[i].cache_hits /= 2;
|
|
}
|
|
|
|
if (min_index == -1) {
|
|
/* This can't happen in current synchronous code, but leave the check
|
|
* here as a reminder for whoever starts using AIO with the cache */
|
|
abort();
|
|
}
|
|
return min_index;
|
|
}
|
|
|
|
static int qcow2_cache_do_get(BlockDriverState *bs, Qcow2Cache *c,
|
|
uint64_t offset, void **table, bool read_from_disk)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
int i;
|
|
int ret;
|
|
|
|
trace_qcow2_cache_get(qemu_coroutine_self(), c == s->l2_table_cache,
|
|
offset, read_from_disk);
|
|
|
|
/* Check if the table is already cached */
|
|
for (i = 0; i < c->size; i++) {
|
|
if (c->entries[i].offset == offset) {
|
|
goto found;
|
|
}
|
|
}
|
|
|
|
/* If not, write a table back and replace it */
|
|
i = qcow2_cache_find_entry_to_replace(c);
|
|
trace_qcow2_cache_get_replace_entry(qemu_coroutine_self(),
|
|
c == s->l2_table_cache, i);
|
|
if (i < 0) {
|
|
return i;
|
|
}
|
|
|
|
ret = qcow2_cache_entry_flush(bs, c, i);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
|
|
trace_qcow2_cache_get_read(qemu_coroutine_self(),
|
|
c == s->l2_table_cache, i);
|
|
c->entries[i].offset = 0;
|
|
if (read_from_disk) {
|
|
if (c == s->l2_table_cache) {
|
|
BLKDBG_EVENT(bs->file, BLKDBG_L2_LOAD);
|
|
}
|
|
|
|
ret = bdrv_pread(bs->file, offset, c->entries[i].table, s->cluster_size);
|
|
if (ret < 0) {
|
|
return ret;
|
|
}
|
|
}
|
|
|
|
/* Give the table some hits for the start so that it won't be replaced
|
|
* immediately. The number 32 is completely arbitrary. */
|
|
c->entries[i].cache_hits = 32;
|
|
c->entries[i].offset = offset;
|
|
|
|
/* And return the right table */
|
|
found:
|
|
c->entries[i].cache_hits++;
|
|
c->entries[i].ref++;
|
|
*table = c->entries[i].table;
|
|
|
|
trace_qcow2_cache_get_done(qemu_coroutine_self(),
|
|
c == s->l2_table_cache, i);
|
|
|
|
return 0;
|
|
}
|
|
|
|
int qcow2_cache_get(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
|
|
void **table)
|
|
{
|
|
return qcow2_cache_do_get(bs, c, offset, table, true);
|
|
}
|
|
|
|
int qcow2_cache_get_empty(BlockDriverState *bs, Qcow2Cache *c, uint64_t offset,
|
|
void **table)
|
|
{
|
|
return qcow2_cache_do_get(bs, c, offset, table, false);
|
|
}
|
|
|
|
int qcow2_cache_put(BlockDriverState *bs, Qcow2Cache *c, void **table)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < c->size; i++) {
|
|
if (c->entries[i].table == *table) {
|
|
goto found;
|
|
}
|
|
}
|
|
return -ENOENT;
|
|
|
|
found:
|
|
c->entries[i].ref--;
|
|
*table = NULL;
|
|
|
|
assert(c->entries[i].ref >= 0);
|
|
return 0;
|
|
}
|
|
|
|
void qcow2_cache_entry_mark_dirty(Qcow2Cache *c, void *table)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < c->size; i++) {
|
|
if (c->entries[i].table == table) {
|
|
goto found;
|
|
}
|
|
}
|
|
abort();
|
|
|
|
found:
|
|
c->entries[i].dirty = true;
|
|
}
|