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qemu/migration/block.c
Kevin Wolf d861ab3acf block: Add BlockBackend.ctx 
This adds a new parameter to blk_new() which requires its callers to
declare from which AioContext this BlockBackend is going to be used (or
the locks of which AioContext need to be taken anyway).

The given context is only stored and kept up to date when changing
AioContexts. Actually applying the stored AioContext to the root node
is saved for another commit.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-06-04 15:22:22 +02:00

1036 lines
29 KiB
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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/osdep.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "qemu/cutils.h"
#include "qemu/queue.h"
#include "block.h"
#include "migration/misc.h"
#include "migration.h"
#include "migration/register.h"
#include "qemu-file.h"
#include "migration/vmstate.h"
#include "sysemu/block-backend.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 BLK_MIG_FLAG_ZERO_BLOCK 0x08
#define MAX_IS_ALLOCATED_SEARCH (65536 * BDRV_SECTOR_SIZE)
#define MAX_IO_BUFFERS 512
#define MAX_PARALLEL_IO 16
//#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 {
/* Written during setup phase. Can be read without a lock. */
BlockBackend *blk;
char *blk_name;
int shared_base;
int64_t total_sectors;
QSIMPLEQ_ENTRY(BlkMigDevState) entry;
Error *blocker;
/* Only used by migration thread. Does not need a lock. */
int bulk_completed;
int64_t cur_sector;
int64_t cur_dirty;
/* Data in the aio_bitmap is protected by block migration lock.
* Allocation and free happen during setup and cleanup respectively.
*/
unsigned long *aio_bitmap;
/* Protected by block migration lock. */
int64_t completed_sectors;
/* During migration this is protected by iothread lock / AioContext.
* Allocation and free happen during setup and cleanup respectively.
*/
BdrvDirtyBitmap *dirty_bitmap;
} BlkMigDevState;
typedef struct BlkMigBlock {
/* Only used by migration thread. */
uint8_t *buf;
BlkMigDevState *bmds;
int64_t sector;
int nr_sectors;
QEMUIOVector qiov;
BlockAIOCB *aiocb;
/* Protected by block migration lock. */
int ret;
QSIMPLEQ_ENTRY(BlkMigBlock) entry;
} BlkMigBlock;
typedef struct BlkMigState {
QSIMPLEQ_HEAD(, BlkMigDevState) bmds_list;
int64_t total_sector_sum;
bool zero_blocks;
/* Protected by lock. */
QSIMPLEQ_HEAD(, BlkMigBlock) blk_list;
int submitted;
int read_done;
/* Only used by migration thread. Does not need a lock. */
int transferred;
int prev_progress;
int bulk_completed;
/* Lock must be taken _inside_ the iothread lock and any AioContexts. */
QemuMutex lock;
} BlkMigState;
static BlkMigState block_mig_state;
static void blk_mig_lock(void)
{
qemu_mutex_lock(&block_mig_state.lock);
}
static void blk_mig_unlock(void)
{
qemu_mutex_unlock(&block_mig_state.lock);
}
/* Must run outside of the iothread lock during the bulk phase,
* or the VM will stall.
*/
static void blk_send(QEMUFile *f, BlkMigBlock * blk)
{
int len;
uint64_t flags = BLK_MIG_FLAG_DEVICE_BLOCK;
if (block_mig_state.zero_blocks &&
buffer_is_zero(blk->buf, BLOCK_SIZE)) {
flags |= BLK_MIG_FLAG_ZERO_BLOCK;
}
/* sector number and flags */
qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
| flags);
/* device name */
len = strlen(blk->bmds->blk_name);
qemu_put_byte(f, len);
qemu_put_buffer(f, (uint8_t *) blk->bmds->blk_name, len);
/* if a block is zero we need to flush here since the network
* bandwidth is now a lot higher than the storage device bandwidth.
* thus if we queue zero blocks we slow down the migration */
if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
qemu_fflush(f);
return;
}
qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
}
int blk_mig_active(void)
{
return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
}
int blk_mig_bulk_active(void)
{
return blk_mig_active() && !block_mig_state.bulk_completed;
}
uint64_t blk_mig_bytes_transferred(void)
{
BlkMigDevState *bmds;
uint64_t sum = 0;
blk_mig_lock();
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
sum += bmds->completed_sectors;
}
blk_mig_unlock();
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;
}
/* Called with migration lock held. */
static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
{
int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
if (sector < blk_nb_sectors(bmds->blk)) {
return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &
(1UL << (chunk % (sizeof(unsigned long) * 8))));
} else {
return 0;
}
}
/* Called with migration lock held. */
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)
{
BlockBackend *bb = bmds->blk;
int64_t bitmap_size;
bitmap_size = blk_nb_sectors(bb) + BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
bmds->aio_bitmap = g_malloc0(bitmap_size);
}
/* Never hold migration lock when yielding to the main loop! */
static void blk_mig_read_cb(void *opaque, int ret)
{
BlkMigBlock *blk = opaque;
blk_mig_lock();
blk->ret = ret;
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);
blk_mig_unlock();
}
/* Called with no lock taken. */
static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
{
int64_t total_sectors = bmds->total_sectors;
int64_t cur_sector = bmds->cur_sector;
BlockBackend *bb = bmds->blk;
BlkMigBlock *blk;
int nr_sectors;
int64_t count;
if (bmds->shared_base) {
qemu_mutex_lock_iothread();
aio_context_acquire(blk_get_aio_context(bb));
/* Skip unallocated sectors; intentionally treats failure or
* partial sector as an allocated sector */
while (cur_sector < total_sectors &&
!bdrv_is_allocated(blk_bs(bb), cur_sector * BDRV_SECTOR_SIZE,
MAX_IS_ALLOCATED_SEARCH, &count)) {
if (count < BDRV_SECTOR_SIZE) {
break;
}
cur_sector += count >> BDRV_SECTOR_BITS;
}
aio_context_release(blk_get_aio_context(bb));
qemu_mutex_unlock_iothread();
}
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_new(BlkMigBlock, 1);
blk->buf = g_malloc(BLOCK_SIZE);
blk->bmds = bmds;
blk->sector = cur_sector;
blk->nr_sectors = nr_sectors;
qemu_iovec_init_buf(&blk->qiov, blk->buf, nr_sectors * BDRV_SECTOR_SIZE);
blk_mig_lock();
block_mig_state.submitted++;
blk_mig_unlock();
/* We do not know if bs is under the main thread (and thus does
* not acquire the AioContext when doing AIO) or rather under
* dataplane. Thus acquire both the iothread mutex and the
* AioContext.
*
* This is ugly and will disappear when we make bdrv_* thread-safe,
* without the need to acquire the AioContext.
*/
qemu_mutex_lock_iothread();
aio_context_acquire(blk_get_aio_context(bmds->blk));
bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, cur_sector * BDRV_SECTOR_SIZE,
nr_sectors * BDRV_SECTOR_SIZE);
blk->aiocb = blk_aio_preadv(bb, cur_sector * BDRV_SECTOR_SIZE, &blk->qiov,
0, blk_mig_read_cb, blk);
aio_context_release(blk_get_aio_context(bmds->blk));
qemu_mutex_unlock_iothread();
bmds->cur_sector = cur_sector + nr_sectors;
return (bmds->cur_sector >= total_sectors);
}
/* Called with iothread lock taken. */
static int set_dirty_tracking(void)
{
BlkMigDevState *bmds;
int ret;
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
bmds->dirty_bitmap = bdrv_create_dirty_bitmap(blk_bs(bmds->blk),
BLOCK_SIZE, NULL, NULL);
if (!bmds->dirty_bitmap) {
ret = -errno;
goto fail;
}
}
return 0;
fail:
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
if (bmds->dirty_bitmap) {
bdrv_release_dirty_bitmap(blk_bs(bmds->blk), bmds->dirty_bitmap);
}
}
return ret;
}
/* Called with iothread lock taken. */
static void unset_dirty_tracking(void)
{
BlkMigDevState *bmds;
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
bdrv_release_dirty_bitmap(blk_bs(bmds->blk), bmds->dirty_bitmap);
}
}
static int init_blk_migration(QEMUFile *f)
{
BlockDriverState *bs;
BlkMigDevState *bmds;
int64_t sectors;
BdrvNextIterator it;
int i, num_bs = 0;
struct {
BlkMigDevState *bmds;
BlockDriverState *bs;
} *bmds_bs;
Error *local_err = NULL;
int ret;
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;
block_mig_state.zero_blocks = migrate_zero_blocks();
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
num_bs++;
}
bmds_bs = g_malloc0(num_bs * sizeof(*bmds_bs));
for (i = 0, bs = bdrv_first(&it); bs; bs = bdrv_next(&it), i++) {
if (bdrv_is_read_only(bs)) {
continue;
}
sectors = bdrv_nb_sectors(bs);
if (sectors <= 0) {
ret = sectors;
bdrv_next_cleanup(&it);
goto out;
}
bmds = g_new0(BlkMigDevState, 1);
bmds->blk = blk_new(qemu_get_aio_context(),
BLK_PERM_CONSISTENT_READ, BLK_PERM_ALL);
bmds->blk_name = g_strdup(bdrv_get_device_name(bs));
bmds->bulk_completed = 0;
bmds->total_sectors = sectors;
bmds->completed_sectors = 0;
bmds->shared_base = migrate_use_block_incremental();
assert(i < num_bs);
bmds_bs[i].bmds = bmds;
bmds_bs[i].bs = bs;
block_mig_state.total_sector_sum += sectors;
if (bmds->shared_base) {
DPRINTF("Start migration for %s with shared base image\n",
bdrv_get_device_name(bs));
} else {
DPRINTF("Start full migration for %s\n", bdrv_get_device_name(bs));
}
QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
}
/* Can only insert new BDSes now because doing so while iterating block
* devices may end up in a deadlock (iterating the new BDSes, too). */
for (i = 0; i < num_bs; i++) {
BlkMigDevState *bmds = bmds_bs[i].bmds;
BlockDriverState *bs = bmds_bs[i].bs;
if (bmds) {
ret = blk_insert_bs(bmds->blk, bs, &local_err);
if (ret < 0) {
error_report_err(local_err);
goto out;
}
alloc_aio_bitmap(bmds);
error_setg(&bmds->blocker, "block device is in use by migration");
bdrv_op_block_all(bs, bmds->blocker);
}
}
ret = 0;
out:
g_free(bmds_bs);
return ret;
}
/* Called with no lock taken. */
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;
}
}
/* Called with iothread lock and AioContext taken. */
static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds,
int is_async)
{
BlkMigBlock *blk;
BlockDriverState *bs = blk_bs(bmds->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;) {
blk_mig_lock();
if (bmds_aio_inflight(bmds, sector)) {
blk_mig_unlock();
blk_drain(bmds->blk);
} else {
blk_mig_unlock();
}
bdrv_dirty_bitmap_lock(bmds->dirty_bitmap);
if (bdrv_get_dirty_locked(bs, bmds->dirty_bitmap,
sector * BDRV_SECTOR_SIZE)) {
if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
nr_sectors = total_sectors - sector;
} else {
nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
}
bdrv_reset_dirty_bitmap_locked(bmds->dirty_bitmap,
sector * BDRV_SECTOR_SIZE,
nr_sectors * BDRV_SECTOR_SIZE);
bdrv_dirty_bitmap_unlock(bmds->dirty_bitmap);
blk = g_new(BlkMigBlock, 1);
blk->buf = g_malloc(BLOCK_SIZE);
blk->bmds = bmds;
blk->sector = sector;
blk->nr_sectors = nr_sectors;
if (is_async) {
qemu_iovec_init_buf(&blk->qiov, blk->buf,
nr_sectors * BDRV_SECTOR_SIZE);
blk->aiocb = blk_aio_preadv(bmds->blk,
sector * BDRV_SECTOR_SIZE,
&blk->qiov, 0, blk_mig_read_cb,
blk);
blk_mig_lock();
block_mig_state.submitted++;
bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
blk_mig_unlock();
} else {
ret = blk_pread(bmds->blk, sector * BDRV_SECTOR_SIZE, blk->buf,
nr_sectors * BDRV_SECTOR_SIZE);
if (ret < 0) {
goto error;
}
blk_send(f, blk);
g_free(blk->buf);
g_free(blk);
}
sector += nr_sectors;
bmds->cur_dirty = sector;
break;
}
bdrv_dirty_bitmap_unlock(bmds->dirty_bitmap);
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;
}
/* Called with iothread lock taken.
*
* 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) {
aio_context_acquire(blk_get_aio_context(bmds->blk));
ret = mig_save_device_dirty(f, bmds, is_async);
aio_context_release(blk_get_aio_context(bmds->blk));
if (ret <= 0) {
break;
}
}
return ret;
}
/* Called with no locks taken. */
static int flush_blks(QEMUFile *f)
{
BlkMigBlock *blk;
int ret = 0;
DPRINTF("%s Enter submitted %d read_done %d transferred %d\n",
__func__, block_mig_state.submitted, block_mig_state.read_done,
block_mig_state.transferred);
blk_mig_lock();
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;
}
QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
blk_mig_unlock();
blk_send(f, blk);
blk_mig_lock();
g_free(blk->buf);
g_free(blk);
block_mig_state.read_done--;
block_mig_state.transferred++;
assert(block_mig_state.read_done >= 0);
}
blk_mig_unlock();
DPRINTF("%s Exit submitted %d read_done %d transferred %d\n", __func__,
block_mig_state.submitted, block_mig_state.read_done,
block_mig_state.transferred);
return ret;
}
/* Called with iothread lock taken. */
static int64_t get_remaining_dirty(void)
{
BlkMigDevState *bmds;
int64_t dirty = 0;
QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
aio_context_acquire(blk_get_aio_context(bmds->blk));
dirty += bdrv_get_dirty_count(bmds->dirty_bitmap);
aio_context_release(blk_get_aio_context(bmds->blk));
}
return dirty;
}
/* Called with iothread lock taken. */
static void block_migration_cleanup_bmds(void)
{
BlkMigDevState *bmds;
AioContext *ctx;
unset_dirty_tracking();
while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
bdrv_op_unblock_all(blk_bs(bmds->blk), bmds->blocker);
error_free(bmds->blocker);
/* Save ctx, because bmds->blk can disappear during blk_unref. */
ctx = blk_get_aio_context(bmds->blk);
aio_context_acquire(ctx);
blk_unref(bmds->blk);
aio_context_release(ctx);
g_free(bmds->blk_name);
g_free(bmds->aio_bitmap);
g_free(bmds);
}
}
/* Called with iothread lock taken. */
static void block_migration_cleanup(void *opaque)
{
BlkMigBlock *blk;
bdrv_drain_all();
block_migration_cleanup_bmds();
blk_mig_lock();
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);
}
blk_mig_unlock();
}
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);
qemu_mutex_lock_iothread();
ret = init_blk_migration(f);
if (ret < 0) {
qemu_mutex_unlock_iothread();
return ret;
}
/* start track dirty blocks */
ret = set_dirty_tracking();
qemu_mutex_unlock_iothread();
if (ret) {
return ret;
}
ret = flush_blks(f);
blk_mig_reset_dirty_cursor();
qemu_put_be64(f, BLK_MIG_FLAG_EOS);
return ret;
}
static int block_save_iterate(QEMUFile *f, void *opaque)
{
int ret;
int64_t last_ftell = qemu_ftell(f);
int64_t delta_ftell;
DPRINTF("Enter save live iterate submitted %d transferred %d\n",
block_mig_state.submitted, block_mig_state.transferred);
ret = flush_blks(f);
if (ret) {
return ret;
}
blk_mig_reset_dirty_cursor();
/* control the rate of transfer */
blk_mig_lock();
while (block_mig_state.read_done * BLOCK_SIZE <
qemu_file_get_rate_limit(f) &&
block_mig_state.submitted < MAX_PARALLEL_IO &&
(block_mig_state.submitted + block_mig_state.read_done) <
MAX_IO_BUFFERS) {
blk_mig_unlock();
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;
}
ret = 0;
} else {
/* Always called with iothread lock taken for
* simplicity, block_save_complete also calls it.
*/
qemu_mutex_lock_iothread();
ret = blk_mig_save_dirty_block(f, 1);
qemu_mutex_unlock_iothread();
}
if (ret < 0) {
return ret;
}
blk_mig_lock();
if (ret != 0) {
/* no more dirty blocks */
break;
}
}
blk_mig_unlock();
ret = flush_blks(f);
if (ret) {
return ret;
}
qemu_put_be64(f, BLK_MIG_FLAG_EOS);
delta_ftell = qemu_ftell(f) - last_ftell;
if (delta_ftell > 0) {
return 1;
} else if (delta_ftell < 0) {
return -1;
} else {
return 0;
}
}
/* Called with iothread lock taken. */
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) {
return ret;
}
blk_mig_reset_dirty_cursor();
/* we know for sure that save bulk is completed and
all async read completed */
blk_mig_lock();
assert(block_mig_state.submitted == 0);
blk_mig_unlock();
do {
ret = blk_mig_save_dirty_block(f, 0);
if (ret < 0) {
return ret;
}
} while (ret == 0);
/* 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);
/* Make sure that our BlockBackends are gone, so that the block driver
* nodes can be inactivated. */
block_migration_cleanup_bmds();
return 0;
}
static void block_save_pending(QEMUFile *f, void *opaque, uint64_t max_size,
uint64_t *res_precopy_only,
uint64_t *res_compatible,
uint64_t *res_postcopy_only)
{
/* Estimate pending number of bytes to send */
uint64_t pending;
qemu_mutex_lock_iothread();
pending = get_remaining_dirty();
qemu_mutex_unlock_iothread();
blk_mig_lock();
pending += block_mig_state.submitted * BLOCK_SIZE +
block_mig_state.read_done * BLOCK_SIZE;
blk_mig_unlock();
/* Report at least one block pending during bulk phase */
if (pending <= max_size && !block_mig_state.bulk_completed) {
pending = max_size + BLOCK_SIZE;
}
DPRINTF("Enter save live pending %" PRIu64 "\n", pending);
/* We don't do postcopy */
*res_precopy_only += 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;
BlockBackend *blk, *blk_prev = NULL;
Error *local_err = NULL;
uint8_t *buf;
int64_t total_sectors = 0;
int nr_sectors;
int ret;
BlockDriverInfo bdi;
int cluster_size = BLOCK_SIZE;
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';
blk = blk_by_name(device_name);
if (!blk) {
fprintf(stderr, "Error unknown block device %s\n",
device_name);
return -EINVAL;
}
if (blk != blk_prev) {
blk_prev = blk;
total_sectors = blk_nb_sectors(blk);
if (total_sectors <= 0) {
error_report("Error getting length of block device %s",
device_name);
return -EINVAL;
}
blk_invalidate_cache(blk, &local_err);
if (local_err) {
error_report_err(local_err);
return -EINVAL;
}
ret = bdrv_get_info(blk_bs(blk), &bdi);
if (ret == 0 && bdi.cluster_size > 0 &&
bdi.cluster_size <= BLOCK_SIZE &&
BLOCK_SIZE % bdi.cluster_size == 0) {
cluster_size = bdi.cluster_size;
} else {
cluster_size = BLOCK_SIZE;
}
}
if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
nr_sectors = total_sectors - addr;
} else {
nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
}
if (flags & BLK_MIG_FLAG_ZERO_BLOCK) {
ret = blk_pwrite_zeroes(blk, addr * BDRV_SECTOR_SIZE,
nr_sectors * BDRV_SECTOR_SIZE,
BDRV_REQ_MAY_UNMAP);
} else {
int i;
int64_t cur_addr;
uint8_t *cur_buf;
buf = g_malloc(BLOCK_SIZE);
qemu_get_buffer(f, buf, BLOCK_SIZE);
for (i = 0; i < BLOCK_SIZE / cluster_size; i++) {
cur_addr = addr * BDRV_SECTOR_SIZE + i * cluster_size;
cur_buf = buf + i * cluster_size;
if ((!block_mig_state.zero_blocks ||
cluster_size < BLOCK_SIZE) &&
buffer_is_zero(cur_buf, cluster_size)) {
ret = blk_pwrite_zeroes(blk, cur_addr,
cluster_size,
BDRV_REQ_MAY_UNMAP);
} else {
ret = blk_pwrite(blk, cur_addr, cur_buf,
cluster_size, 0);
}
if (ret < 0) {
break;
}
}
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 bool block_is_active(void *opaque)
{
return migrate_use_block();
}
static SaveVMHandlers savevm_block_handlers = {
.save_setup = block_save_setup,
.save_live_iterate = block_save_iterate,
.save_live_complete_precopy = block_save_complete,
.save_live_pending = block_save_pending,
.load_state = block_load,
.save_cleanup = block_migration_cleanup,
.is_active = block_is_active,
};
void blk_mig_init(void)
{
QSIMPLEQ_INIT(&block_mig_state.bmds_list);
QSIMPLEQ_INIT(&block_mig_state.blk_list);
qemu_mutex_init(&block_mig_state.lock);
register_savevm_live(NULL, "block", 0, 1, &savevm_block_handlers,
&block_mig_state);
}
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