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qemu/block-migration.c

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/*
* QEMU live block migration
*
* Copyright IBM, Corp. 2009
*
* Authors:
* Liran Schour <lirans@il.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include "qemu-common.h"
#include "block_int.h"
#include "hw/hw.h"
#include "block-migration.h"
#include <assert.h>
#define SECTOR_BITS 9
#define SECTOR_SIZE (1 << SECTOR_BITS)
#define SECTOR_MASK ~(SECTOR_SIZE - 1);
#define BLOCK_SIZE (block_mig_state->sectors_per_block << SECTOR_BITS)
#define BLK_MIG_FLAG_DEVICE_BLOCK 0x01
#define BLK_MIG_FLAG_EOS 0x02
#define MAX_IS_ALLOCATED_SEARCH 65536
#define MAX_BLOCKS_READ 10000
#define BLOCKS_READ_CHANGE 100
#define INITIAL_BLOCKS_READ 100
//#define DEBUG_BLK_MIGRATION
#ifdef DEBUG_BLK_MIGRATION
#define dprintf(fmt, ...) \
do { printf("blk_migration: " fmt, ## __VA_ARGS__); } while (0)
#else
#define dprintf(fmt, ...) \
do { } while (0)
#endif
typedef struct BlkMigBlock {
uint8_t *buf;
BlkMigDevState *bmds;
int64_t sector;
struct iovec iov;
QEMUIOVector qiov;
BlockDriverAIOCB *aiocb;
int ret;
struct BlkMigBlock *next;
} BlkMigBlock;
typedef struct BlkMigState {
int bulk_completed;
int blk_enable;
int shared_base;
int no_dirty;
QEMUFile *load_file;
BlkMigDevState *bmds_first;
int sectors_per_block;
BlkMigBlock *first_blk;
BlkMigBlock *last_blk;
int submitted;
int read_done;
int transferred;
int64_t print_completion;
} BlkMigState;
static BlkMigState *block_mig_state = NULL;
static void blk_mig_read_cb(void *opaque, int ret)
{
BlkMigBlock *blk = opaque;
blk->ret = ret;
/* insert at the end */
if(block_mig_state->last_blk == NULL) {
block_mig_state->first_blk = blk;
block_mig_state->last_blk = blk;
} else {
block_mig_state->last_blk->next = blk;
block_mig_state->last_blk = blk;
}
block_mig_state->submitted--;
block_mig_state->read_done++;
assert(block_mig_state->submitted >= 0);
return;
}
static int mig_read_device_bulk(QEMUFile *f, BlkMigDevState *bms)
{
int nr_sectors;
int64_t total_sectors, cur_sector = 0;
BlockDriverState *bs = bms->bs;
BlkMigBlock *blk;
blk = qemu_malloc(sizeof(BlkMigBlock));
blk->buf = qemu_malloc(BLOCK_SIZE);
cur_sector = bms->cur_sector;
total_sectors = bdrv_getlength(bs) >> SECTOR_BITS;
if(bms->shared_base) {
while(cur_sector < bms->total_sectors &&
!bdrv_is_allocated(bms->bs, cur_sector,
MAX_IS_ALLOCATED_SEARCH, &nr_sectors)) {
cur_sector += nr_sectors;
}
}
if(cur_sector >= total_sectors) {
bms->cur_sector = total_sectors;
qemu_free(blk->buf);
qemu_free(blk);
return 1;
}
if(cur_sector >= block_mig_state->print_completion) {
printf("Completed %" PRId64 " %%\r", cur_sector * 100 / total_sectors);
fflush(stdout);
block_mig_state->print_completion +=
(block_mig_state->sectors_per_block * 10000);
}
/* we going to transfder BLOCK_SIZE any way even if it is not allocated */
nr_sectors = block_mig_state->sectors_per_block;
cur_sector &= ~((int64_t)block_mig_state->sectors_per_block -1);
if(total_sectors - cur_sector < block_mig_state->sectors_per_block) {
nr_sectors = (total_sectors - cur_sector);
}
bms->cur_sector = cur_sector + nr_sectors;
blk->sector = cur_sector;
blk->bmds = bms;
blk->next = NULL;
blk->iov.iov_base = blk->buf;
blk->iov.iov_len = nr_sectors * SECTOR_SIZE;
qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
nr_sectors, blk_mig_read_cb, blk);
if(!blk->aiocb) {
printf("Error reading sector %" PRId64 "\n", cur_sector);
qemu_free(blk->buf);
qemu_free(blk);
return 0;
}
bdrv_reset_dirty(bms->bs, cur_sector, nr_sectors);
block_mig_state->submitted++;
return (bms->cur_sector >= total_sectors);
}
static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
{
int len, nr_sectors;
int64_t total_sectors = bmds->total_sectors, cur_sector = 0;
uint8_t *tmp_buf = NULL;
BlockDriverState *bs = bmds->bs;
tmp_buf = qemu_malloc(BLOCK_SIZE);
cur_sector = bmds->cur_sector;
if(bmds->shared_base) {
while(cur_sector < bmds->total_sectors &&
!bdrv_is_allocated(bmds->bs, cur_sector,
MAX_IS_ALLOCATED_SEARCH, &nr_sectors)) {
cur_sector += nr_sectors;
}
}
if(cur_sector >= total_sectors) {
bmds->cur_sector = total_sectors;
qemu_free(tmp_buf);
return 1;
}
if(cur_sector >= block_mig_state->print_completion) {
printf("Completed %" PRId64 " %%\r", cur_sector * 100 / total_sectors);
fflush(stdout);
block_mig_state->print_completion +=
(block_mig_state->sectors_per_block * 10000);
}
cur_sector &= ~((int64_t)block_mig_state->sectors_per_block -1);
/* we going to transfer
BLOCK_SIZE
any way even if it is not allocated */
nr_sectors = block_mig_state->sectors_per_block;
if(total_sectors - cur_sector < block_mig_state->sectors_per_block) {
nr_sectors = (total_sectors - cur_sector);
}
if(bdrv_read(bs, cur_sector, tmp_buf, nr_sectors) < 0) {
printf("Error reading sector %" PRId64 "\n", cur_sector);
}
bdrv_reset_dirty(bs, cur_sector, nr_sectors);
/* Device name */
qemu_put_be64(f,(cur_sector << SECTOR_BITS) | BLK_MIG_FLAG_DEVICE_BLOCK);
len = strlen(bs->device_name);
qemu_put_byte(f, len);
qemu_put_buffer(f, (uint8_t *)bs->device_name, len);
qemu_put_buffer(f, tmp_buf,
BLOCK_SIZE);
bmds->cur_sector = cur_sector + block_mig_state->sectors_per_block;
qemu_free(tmp_buf);
return (bmds->cur_sector >= total_sectors);
}
static void send_blk(QEMUFile *f, BlkMigBlock * blk)
{
int len;
/* Device name */
qemu_put_be64(f,(blk->sector << SECTOR_BITS) | BLK_MIG_FLAG_DEVICE_BLOCK);
len = strlen(blk->bmds->bs->device_name);
qemu_put_byte(f, len);
qemu_put_buffer(f, (uint8_t *)blk->bmds->bs->device_name, len);
qemu_put_buffer(f, blk->buf,
BLOCK_SIZE);
return;
}
static void blk_mig_save_dev_info(QEMUFile *f, BlkMigDevState *bmds)
{
}
static void set_dirty_tracking(int enable)
{
BlkMigDevState *bmds;
for(bmds = block_mig_state->bmds_first; bmds != NULL; bmds = bmds->next) {
bdrv_set_dirty_tracking(bmds->bs,enable);
}
return;
}
static void init_blk_migration(QEMUFile *f)
{
BlkMigDevState **pbmds, *bmds;
BlockDriverState *bs;
for (bs = bdrv_first; bs != NULL; bs = bs->next) {
if(bs->type == BDRV_TYPE_HD) {
bmds = qemu_mallocz(sizeof(BlkMigDevState));
bmds->bs = bs;
bmds->bulk_completed = 0;
bmds->total_sectors = bdrv_getlength(bs) >> SECTOR_BITS;
bmds->shared_base = block_mig_state->shared_base;
if(bmds->shared_base) {
printf("Start migration for %s with shared base image\n",
bs->device_name);
} else {
printf("Start full migration for %s\n", bs->device_name);
}
/* insert at the end */
pbmds = &block_mig_state->bmds_first;
while (*pbmds != NULL)
pbmds = &(*pbmds)->next;
*pbmds = bmds;
blk_mig_save_dev_info(f, bmds);
}
}
block_mig_state->sectors_per_block = bdrv_get_sectors_per_chunk();
return;
}
static int blk_mig_save_bulked_block(QEMUFile *f, int is_async)
{
BlkMigDevState *bmds;
for (bmds = block_mig_state->bmds_first; bmds != NULL; bmds = bmds->next) {
if(bmds->bulk_completed == 0) {
if(is_async) {
if(mig_read_device_bulk(f, bmds) == 1) {
/* completed bulk section for this device */
bmds->bulk_completed = 1;
}
} else {
if(mig_save_device_bulk(f,bmds) == 1) {
/* completed bulk section for this device */
bmds->bulk_completed = 1;
}
}
return 1;
}
}
/* we reached here means bulk is completed */
block_mig_state->bulk_completed = 1;
return 0;
}
#define MAX_NUM_BLOCKS 4
static void blk_mig_save_dirty_blocks(QEMUFile *f)
{
BlkMigDevState *bmds;
uint8_t buf[BLOCK_SIZE];
int64_t sector;
int len;
for(bmds = block_mig_state->bmds_first; bmds != NULL; bmds = bmds->next) {
for(sector = 0; sector < bmds->cur_sector;) {
if(bdrv_get_dirty(bmds->bs,sector)) {
if(bdrv_read(bmds->bs, sector, buf,
block_mig_state->sectors_per_block) < 0) {
}
/* device name */
qemu_put_be64(f,(sector << SECTOR_BITS)
| BLK_MIG_FLAG_DEVICE_BLOCK);
len = strlen(bmds->bs->device_name);
qemu_put_byte(f, len);
qemu_put_buffer(f, (uint8_t *)bmds->bs->device_name, len);
qemu_put_buffer(f, buf,
(block_mig_state->sectors_per_block *
SECTOR_SIZE));
bdrv_reset_dirty(bmds->bs, sector,
block_mig_state->sectors_per_block);
sector += block_mig_state->sectors_per_block;
} else {
/* sector is clean */
sector += block_mig_state->sectors_per_block;
}
}
}
return;
}
static void flush_blks(QEMUFile* f)
{
BlkMigBlock *blk, *tmp;
dprintf("%s Enter submitted %d read_done %d transfered\n", __FUNCTION__,
submitted, read_done, transfered);
for(blk = block_mig_state->first_blk;
blk != NULL && !qemu_file_rate_limit(f); blk = tmp) {
send_blk(f, blk);
tmp = blk->next;
qemu_free(blk->buf);
qemu_free(blk);
block_mig_state->read_done--;
block_mig_state->transferred++;
assert(block_mig_state->read_done >= 0);
}
block_mig_state->first_blk = blk;
if(block_mig_state->first_blk == NULL) {
block_mig_state->last_blk = NULL;
}
dprintf("%s Exit submitted %d read_done %d transferred%d\n", __FUNCTION__,
block_mig_state->submitted, block_mig_state->read_done,
block_mig_state->transferred);
return;
}
static int is_stage2_completed(void)
{
BlkMigDevState *bmds;
if(block_mig_state->submitted > 0) {
return 0;
}
for (bmds = block_mig_state->bmds_first; bmds != NULL; bmds = bmds->next) {
if(bmds->bulk_completed == 0) {
return 0;
}
}
return 1;
}
static int block_save_live(QEMUFile *f, int stage, void *opaque)
{
int ret = 1;
dprintf("Enter save live stage %d submitted %d transferred %d\n", stage,
submitted, transferred);
if(block_mig_state->blk_enable != 1) {
/* no need to migrate storage */
qemu_put_be64(f,BLK_MIG_FLAG_EOS);
return 1;
}
if(stage == 1) {
init_blk_migration(f);
/* start track dirty blocks */
set_dirty_tracking(1);
}
flush_blks(f);
/* control the rate of transfer */
while ((block_mig_state->submitted + block_mig_state->read_done) *
(BLOCK_SIZE) <
(qemu_file_get_rate_limit(f))) {
ret = blk_mig_save_bulked_block(f, 1);
if (ret == 0) /* no more bulk blocks for now*/
break;
}
flush_blks(f);
if(stage == 3) {
while(blk_mig_save_bulked_block(f, 0) != 0);
blk_mig_save_dirty_blocks(f);
/* stop track dirty blocks */
set_dirty_tracking(0);;
printf("\nBlock migration completed\n");
}
qemu_put_be64(f,BLK_MIG_FLAG_EOS);
return ((stage == 2) && is_stage2_completed());
}
static int block_load(QEMUFile *f, void *opaque, int version_id)
{
int len, flags;
char device_name[256];
int64_t addr;
BlockDriverState *bs;
uint8_t *buf;
block_mig_state->sectors_per_block = bdrv_get_sectors_per_chunk();
buf = qemu_malloc(BLOCK_SIZE);
do {
addr = qemu_get_be64(f);
flags = addr & ~SECTOR_MASK;
addr &= SECTOR_MASK;
if(flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
/* get device name */
len = qemu_get_byte(f);
qemu_get_buffer(f, (uint8_t *)device_name, len);
device_name[len] = '\0';
bs = bdrv_find(device_name);
qemu_get_buffer(f, buf,
BLOCK_SIZE);
if(bs != NULL) {
bdrv_write(bs, (addr >> SECTOR_BITS),
buf, block_mig_state->sectors_per_block);
} else {
printf("Error unknown block device %s\n", device_name);
}
} else if(flags & BLK_MIG_FLAG_EOS) {
} else {
printf("Unknown flags\n");
}
} while(!(flags & BLK_MIG_FLAG_EOS));
qemu_free(buf);
return 0;
}
static void block_set_params(int blk_enable, int shared_base, void *opaque)
{
assert(opaque == block_mig_state);
block_mig_state->blk_enable = blk_enable;
block_mig_state->shared_base = shared_base;
/* shared base means that blk_enable = 1 */
block_mig_state->blk_enable |= shared_base;
return;
}
void blk_mig_info(void)
{
BlockDriverState *bs;
for (bs = bdrv_first; bs != NULL; bs = bs->next) {
printf("Device %s\n", bs->device_name);
if(bs->type == BDRV_TYPE_HD) {
printf("device %s format %s\n",
bs->device_name, bs->drv->format_name);
}
}
}
void blk_mig_init(void)
{
block_mig_state = qemu_mallocz(sizeof(BlkMigState));
register_savevm_live("block", 0, 1, block_set_params, block_save_live,
NULL, block_load, block_mig_state);
}
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