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xemu/block-migration.c
Stefan Hajnoczi 6aaa9dae80 block-migration: fix pending() and iterate() return values 
The return value of .save_live_pending() is the number of bytes
remaining.  This is just an estimate because we do not know how many
blocks will be dirtied by the running guest.

Currently our return value for .save_live_pending() is wrong because it
includes dirty blocks but not in-flight bdrv_aio_readv() requests or
unsent blocks.  Crucially, it also doesn't include the bulk phase where
the entire device is transferred - therefore we risk completing block
migration before all blocks have been transferred!

The return value of .save_live_iterate() is the number of bytes
transferred this iteration.  Currently we return whether there are bytes
remaining, which is incorrect.

Move the bytes remaining calculation into .save_live_pending() and
really return the number of bytes transferred this iteration in
.save_live_iterate().

Also fix the %ld format specifier which was used for a uint64_t
argument.  PRIu64 must be use to avoid warnings on 32-bit hosts.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Message-id: 1360661835-28663-3-git-send-email-stefanha@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2013-02-12 16:26:44 -06:00

752 lines
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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.
*
* Contributions after 2012-01-13 are licensed under the terms of the
* GNU GPL, version 2 or (at your option) any later version.
*/
#include "qemu-common.h"
#include "block/block_int.h"
#include "hw/hw.h"
#include "qemu/queue.h"
#include "qemu/timer.h"
#include "migration/block.h"
#include "migration/migration.h"
#include "sysemu/blockdev.h"
#include <assert.h>
#define BLOCK_SIZE (1 << 20)
#define BDRV_SECTORS_PER_DIRTY_CHUNK (BLOCK_SIZE >> BDRV_SECTOR_BITS)
#define BLK_MIG_FLAG_DEVICE_BLOCK 0x01
#define BLK_MIG_FLAG_EOS 0x02
#define BLK_MIG_FLAG_PROGRESS 0x04
#define MAX_IS_ALLOCATED_SEARCH 65536
//#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 BlkMigDevState {
BlockDriverState *bs;
int bulk_completed;
int shared_base;
int64_t cur_sector;
int64_t cur_dirty;
int64_t completed_sectors;
int64_t total_sectors;
int64_t dirty;
QSIMPLEQ_ENTRY(BlkMigDevState) entry;
unsigned long *aio_bitmap;
} BlkMigDevState;
typedef struct BlkMigBlock {
uint8_t *buf;
BlkMigDevState *bmds;
int64_t sector;
int nr_sectors;
struct iovec iov;
QEMUIOVector qiov;
BlockDriverAIOCB *aiocb;
int ret;
QSIMPLEQ_ENTRY(BlkMigBlock) entry;
} BlkMigBlock;
typedef struct BlkMigState {
int blk_enable;
int shared_base;
QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
int submitted;
int read_done;
int transferred;
int64_t total_sector_sum;
int prev_progress;
int bulk_completed;
long double prev_time_offset;
} BlkMigState;
static BlkMigState block_mig_state;
static void blk_send(QEMUFile *f, BlkMigBlock * blk)
{
int len;
/* sector number and flags */
qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
| BLK_MIG_FLAG_DEVICE_BLOCK);
/* device name */
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);
}
int blk_mig_active(void)
{
return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
}
uint64_t blk_mig_bytes_transferred(void)
{
BlkMigDevState *bmds;
uint64_t sum = 0;
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
sum += bmds->completed_sectors;
}
return sum << BDRV_SECTOR_BITS;
}
uint64_t blk_mig_bytes_remaining(void)
{
return blk_mig_bytes_total() - blk_mig_bytes_transferred();
}
uint64_t blk_mig_bytes_total(void)
{
BlkMigDevState *bmds;
uint64_t sum = 0;
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
sum += bmds->total_sectors;
}
return sum << BDRV_SECTOR_BITS;
}
static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
{
int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
if ((sector << BDRV_SECTOR_BITS) < bdrv_getlength(bmds->bs)) {
return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &
(1UL << (chunk % (sizeof(unsigned long) * 8))));
} else {
return 0;
}
}
static void bmds_set_aio_inflight(BlkMigDevState *bmds, int64_t sector_num,
int nb_sectors, int set)
{
int64_t start, end;
unsigned long val, idx, bit;
start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
for (; start <= end; start++) {
idx = start / (sizeof(unsigned long) * 8);
bit = start % (sizeof(unsigned long) * 8);
val = bmds->aio_bitmap[idx];
if (set) {
val |= 1UL << bit;
} else {
val &= ~(1UL << bit);
}
bmds->aio_bitmap[idx] = val;
}
}
static void alloc_aio_bitmap(BlkMigDevState *bmds)
{
BlockDriverState *bs = bmds->bs;
int64_t bitmap_size;
bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS) +
BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
bmds->aio_bitmap = g_malloc0(bitmap_size);
}
static void blk_mig_read_cb(void *opaque, int ret)
{
long double curr_time = qemu_get_clock_ns(rt_clock);
BlkMigBlock *blk = opaque;
blk->ret = ret;
block_mig_state.prev_time_offset = curr_time;
QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);
bmds_set_aio_inflight(blk->bmds, blk->sector, blk->nr_sectors, 0);
block_mig_state.submitted--;
block_mig_state.read_done++;
assert(block_mig_state.submitted >= 0);
}
static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
{
int64_t total_sectors = bmds->total_sectors;
int64_t cur_sector = bmds->cur_sector;
BlockDriverState *bs = bmds->bs;
BlkMigBlock *blk;
int nr_sectors;
if (bmds->shared_base) {
while (cur_sector < total_sectors &&
!bdrv_is_allocated(bs, cur_sector, MAX_IS_ALLOCATED_SEARCH,
&nr_sectors)) {
cur_sector += nr_sectors;
}
}
if (cur_sector >= total_sectors) {
bmds->cur_sector = bmds->completed_sectors = total_sectors;
return 1;
}
bmds->completed_sectors = cur_sector;
cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
/* we are going to transfer a full block even if it is not allocated */
nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
nr_sectors = total_sectors - cur_sector;
}
blk = g_malloc(sizeof(BlkMigBlock));
blk->buf = g_malloc(BLOCK_SIZE);
blk->bmds = bmds;
blk->sector = cur_sector;
blk->nr_sectors = nr_sectors;
blk->iov.iov_base = blk->buf;
blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
if (block_mig_state.submitted == 0) {
block_mig_state.prev_time_offset = qemu_get_clock_ns(rt_clock);
}
blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
nr_sectors, blk_mig_read_cb, blk);
block_mig_state.submitted++;
bdrv_reset_dirty(bs, cur_sector, nr_sectors);
bmds->cur_sector = cur_sector + nr_sectors;
return (bmds->cur_sector >= total_sectors);
}
static void set_dirty_tracking(int enable)
{
BlkMigDevState *bmds;
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
bdrv_set_dirty_tracking(bmds->bs, enable ? BLOCK_SIZE : 0);
}
}
static void init_blk_migration_it(void *opaque, BlockDriverState *bs)
{
BlkMigDevState *bmds;
int64_t sectors;
if (!bdrv_is_read_only(bs)) {
sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
if (sectors <= 0) {
return;
}
bmds = g_malloc0(sizeof(BlkMigDevState));
bmds->bs = bs;
bmds->bulk_completed = 0;
bmds->total_sectors = sectors;
bmds->completed_sectors = 0;
bmds->shared_base = block_mig_state.shared_base;
alloc_aio_bitmap(bmds);
drive_get_ref(drive_get_by_blockdev(bs));
bdrv_set_in_use(bs, 1);
block_mig_state.total_sector_sum += sectors;
if (bmds->shared_base) {
DPRINTF("Start migration for %s with shared base image\n",
bs->device_name);
} else {
DPRINTF("Start full migration for %s\n", bs->device_name);
}
QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
}
}
static void init_blk_migration(QEMUFile *f)
{
block_mig_state.submitted = 0;
block_mig_state.read_done = 0;
block_mig_state.transferred = 0;
block_mig_state.total_sector_sum = 0;
block_mig_state.prev_progress = -1;
block_mig_state.bulk_completed = 0;
bdrv_iterate(init_blk_migration_it, NULL);
}
static int blk_mig_save_bulked_block(QEMUFile *f)
{
int64_t completed_sector_sum = 0;
BlkMigDevState *bmds;
int progress;
int ret = 0;
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
if (bmds->bulk_completed == 0) {
if (mig_save_device_bulk(f, bmds) == 1) {
/* completed bulk section for this device */
bmds->bulk_completed = 1;
}
completed_sector_sum += bmds->completed_sectors;
ret = 1;
break;
} else {
completed_sector_sum += bmds->completed_sectors;
}
}
if (block_mig_state.total_sector_sum != 0) {
progress = completed_sector_sum * 100 /
block_mig_state.total_sector_sum;
} else {
progress = 100;
}
if (progress != block_mig_state.prev_progress) {
block_mig_state.prev_progress = progress;
qemu_put_be64(f, (progress << BDRV_SECTOR_BITS)
| BLK_MIG_FLAG_PROGRESS);
DPRINTF("Completed %d %%\r", progress);
}
return ret;
}
static void blk_mig_reset_dirty_cursor(void)
{
BlkMigDevState *bmds;
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
bmds->cur_dirty = 0;
}
}
static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
int is_async)
{
BlkMigBlock *blk;
int64_t total_sectors = bmds->total_sectors;
int64_t sector;
int nr_sectors;
int ret = -EIO;
for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
if (bmds_aio_inflight(bmds, sector)) {
bdrv_drain_all();
}
if (bdrv_get_dirty(bmds->bs, sector)) {
if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
nr_sectors = total_sectors - sector;
} else {
nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
}
blk = g_malloc(sizeof(BlkMigBlock));
blk->buf = g_malloc(BLOCK_SIZE);
blk->bmds = bmds;
blk->sector = sector;
blk->nr_sectors = nr_sectors;
if (is_async) {
blk->iov.iov_base = blk->buf;
blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
if (block_mig_state.submitted == 0) {
block_mig_state.prev_time_offset = qemu_get_clock_ns(rt_clock);
}
blk->aiocb = bdrv_aio_readv(bmds->bs, sector, &blk->qiov,
nr_sectors, blk_mig_read_cb, blk);
block_mig_state.submitted++;
bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
} else {
ret = bdrv_read(bmds->bs, sector, blk->buf, nr_sectors);
if (ret < 0) {
goto error;
}
blk_send(f, blk);
g_free(blk->buf);
g_free(blk);
}
bdrv_reset_dirty(bmds->bs, sector, nr_sectors);
break;
}
sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
bmds->cur_dirty = sector;
}
return (bmds->cur_dirty >= bmds->total_sectors);
error:
DPRINTF("Error reading sector %" PRId64 "\n", sector);
g_free(blk->buf);
g_free(blk);
return ret;
}
/* return value:
* 0: too much data for max_downtime
* 1: few enough data for max_downtime
*/
static int blk_mig_save_dirty_block(QEMUFile *f, int is_async)
{
BlkMigDevState *bmds;
int ret = 1;
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
ret = mig_save_device_dirty(f, bmds, is_async);
if (ret <= 0) {
break;
}
}
return ret;
}
static int flush_blks(QEMUFile *f)
{
BlkMigBlock *blk;
int ret = 0;
DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
__FUNCTION__, block_mig_state.submitted, block_mig_state.read_done,
block_mig_state.transferred);
while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
if (qemu_file_rate_limit(f)) {
break;
}
if (blk->ret < 0) {
ret = blk->ret;
break;
}
blk_send(f, blk);
QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
g_free(blk->buf);
g_free(blk);
block_mig_state.read_done--;
block_mig_state.transferred++;
assert(block_mig_state.read_done >= 0);
}
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 ret;
}
static int64_t get_remaining_dirty(void)
{
BlkMigDevState *bmds;
int64_t dirty = 0;
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
dirty += bdrv_get_dirty_count(bmds->bs);
}
return dirty << BDRV_SECTOR_BITS;
}
static void blk_mig_cleanup(void)
{
BlkMigDevState *bmds;
BlkMigBlock *blk;
bdrv_drain_all();
set_dirty_tracking(0);
while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
bdrv_set_in_use(bmds->bs, 0);
drive_put_ref(drive_get_by_blockdev(bmds->bs));
g_free(bmds->aio_bitmap);
g_free(bmds);
}
while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
g_free(blk->buf);
g_free(blk);
}
}
static void block_migration_cancel(void *opaque)
{
blk_mig_cleanup();
}
static int block_save_setup(QEMUFile *f, void *opaque)
{
int ret;
DPRINTF("Enter save live setup submitted %d transferred %d\n",
block_mig_state.submitted, block_mig_state.transferred);
init_blk_migration(f);
/* start track dirty blocks */
set_dirty_tracking(1);
ret = flush_blks(f);
if (ret) {
blk_mig_cleanup();
return ret;
}
blk_mig_reset_dirty_cursor();
qemu_put_be64(f, BLK_MIG_FLAG_EOS);
return 0;
}
static int block_save_iterate(QEMUFile *f, void *opaque)
{
int ret;
int64_t last_ftell = qemu_ftell(f);
DPRINTF("Enter save live iterate submitted %d transferred %d\n",
block_mig_state.submitted, block_mig_state.transferred);
ret = flush_blks(f);
if (ret) {
blk_mig_cleanup();
return ret;
}
blk_mig_reset_dirty_cursor();
/* control the rate of transfer */
while ((block_mig_state.submitted +
block_mig_state.read_done) * BLOCK_SIZE <
qemu_file_get_rate_limit(f)) {
if (block_mig_state.bulk_completed == 0) {
/* first finish the bulk phase */
if (blk_mig_save_bulked_block(f) == 0) {
/* finished saving bulk on all devices */
block_mig_state.bulk_completed = 1;
}
} else {
ret = blk_mig_save_dirty_block(f, 1);
if (ret != 0) {
/* no more dirty blocks */
break;
}
}
}
if (ret < 0) {
blk_mig_cleanup();
return ret;
}
ret = flush_blks(f);
if (ret) {
blk_mig_cleanup();
return ret;
}
qemu_put_be64(f, BLK_MIG_FLAG_EOS);
return qemu_ftell(f) - last_ftell;
}
static int block_save_complete(QEMUFile *f, void *opaque)
{
int ret;
DPRINTF("Enter save live complete submitted %d transferred %d\n",
block_mig_state.submitted, block_mig_state.transferred);
ret = flush_blks(f);
if (ret) {
blk_mig_cleanup();
return ret;
}
blk_mig_reset_dirty_cursor();
/* we know for sure that save bulk is completed and
all async read completed */
assert(block_mig_state.submitted == 0);
do {
ret = blk_mig_save_dirty_block(f, 0);
} while (ret == 0);
blk_mig_cleanup();
if (ret < 0) {
return ret;
}
/* report completion */
qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
DPRINTF("Block migration completed\n");
qemu_put_be64(f, BLK_MIG_FLAG_EOS);
return 0;
}
static uint64_t block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size)
{
/* Estimate pending number of bytes to send */
uint64_t pending = get_remaining_dirty() +
block_mig_state.submitted * BLOCK_SIZE +
block_mig_state.read_done * BLOCK_SIZE;
/* Report at least one block pending during bulk phase */
if (pending == 0 && !block_mig_state.bulk_completed) {
pending = BLOCK_SIZE;
}
DPRINTF("Enter save live pending %" PRIu64 "\n", pending);
return pending;
}
static int block_load(QEMUFile *f, void *opaque, int version_id)
{
static int banner_printed;
int len, flags;
char device_name[256];
int64_t addr;
BlockDriverState *bs, *bs_prev = NULL;
uint8_t *buf;
int64_t total_sectors = 0;
int nr_sectors;
int ret;
do {
addr = qemu_get_be64(f);
flags = addr & ~BDRV_SECTOR_MASK;
addr >>= BDRV_SECTOR_BITS;
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);
if (!bs) {
fprintf(stderr, "Error unknown block device %s\n",
device_name);
return -EINVAL;
}
if (bs != bs_prev) {
bs_prev = bs;
total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
if (total_sectors <= 0) {
error_report("Error getting length of block device %s",
device_name);
return -EINVAL;
}
}
if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
nr_sectors = total_sectors - addr;
} else {
nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
}
buf = g_malloc(BLOCK_SIZE);
qemu_get_buffer(f, buf, BLOCK_SIZE);
ret = bdrv_write(bs, addr, buf, nr_sectors);
g_free(buf);
if (ret < 0) {
return ret;
}
} else if (flags & BLK_MIG_FLAG_PROGRESS) {
if (!banner_printed) {
printf("Receiving block device images\n");
banner_printed = 1;
}
printf("Completed %d %%%c", (int)addr,
(addr == 100) ? '\n' : '\r');
fflush(stdout);
} else if (!(flags & BLK_MIG_FLAG_EOS)) {
fprintf(stderr, "Unknown block migration flags: %#x\n", flags);
return -EINVAL;
}
ret = qemu_file_get_error(f);
if (ret != 0) {
return ret;
}
} while (!(flags & BLK_MIG_FLAG_EOS));
return 0;
}
static void block_set_params(const MigrationParams *params, void *opaque)
{
block_mig_state.blk_enable = params->blk;
block_mig_state.shared_base = params->shared;
/* shared base means that blk_enable = 1 */
block_mig_state.blk_enable |= params->shared;
}
static bool block_is_active(void *opaque)
{
return block_mig_state.blk_enable == 1;
}
SaveVMHandlers savevm_block_handlers = {
.set_params = block_set_params,
.save_live_setup = block_save_setup,
.save_live_iterate = block_save_iterate,
.save_live_complete = block_save_complete,
.save_live_pending = block_save_pending,
.load_state = block_load,
.cancel = block_migration_cancel,
.is_active = block_is_active,
};
void blk_mig_init(void)
{
QSIMPLEQ_INIT(&block_mig_state.bmds_list);
QSIMPLEQ_INIT(&block_mig_state.blk_list);
register_savevm_live(NULL, "block", 0, 1, &savevm_block_handlers,
&block_mig_state);
}
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