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qemu-e2k/migration/block.c
Paolo Bonzini 2c5451ca52 migration/block: replace uses of blk_nb_sectors that do not check result 
Uses of blk_nb_sectors must check whether the result is negative.
Otherwise, underflow can happen.  Fortunately, alloc_aio_bitmap()
and bmds_aio_inflight() both have an alternative way to retrieve the
number of sectors in the file.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20230407153303.391121-6-pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-04-11 16:40:53 +02:00

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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/main-loop.h"
#include "qemu/cutils.h"
#include "qemu/queue.h"
#include "block.h"
#include "block/dirty-bitmap.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"
#include "trace.h"
#define BLK_MIG_BLOCK_SIZE (1ULL << 20)
#define BDRV_SECTORS_PER_DIRTY_CHUNK (BLK_MIG_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
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, BLK_MIG_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, BLK_MIG_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 < bmds->total_sectors) {
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)
{
int64_t bitmap_size;
bitmap_size = bmds->total_sectors + 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(BLK_MIG_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),
BLK_MIG_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(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(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) {
trace_migration_block_init_shared(bdrv_get_device_name(bs));
} else {
trace_migration_block_init_full(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);
trace_migration_block_progression(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;
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_dirty_bitmap_get_locked(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(BLK_MIG_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,
nr_sectors * BDRV_SECTOR_SIZE, blk->buf, 0);
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:
trace_migration_block_save_device_dirty(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;
trace_migration_block_flush_blks("Enter", 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();
trace_migration_block_flush_blks("Exit", 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;
trace_migration_block_save("setup", 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_bytes = qemu_file_total_transferred(f);
int64_t delta_bytes;
trace_migration_block_save("iterate", 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 * BLK_MIG_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_bytes = qemu_file_total_transferred(f) - last_bytes;
if (delta_bytes > 0) {
return 1;
} else if (delta_bytes < 0) {
return -1;
} else {
return 0;
}
}
/* Called with iothread lock taken. */
static int block_save_complete(QEMUFile *f, void *opaque)
{
int ret;
trace_migration_block_save("complete", 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);
trace_migration_block_save_complete();
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_state_pending(void *opaque, uint64_t *must_precopy,
uint64_t *can_postcopy)
{
/* 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 * BLK_MIG_BLOCK_SIZE +
block_mig_state.read_done * BLK_MIG_BLOCK_SIZE;
blk_mig_unlock();
/* Report at least one block pending during bulk phase */
if (!pending && !block_mig_state.bulk_completed) {
pending = BLK_MIG_BLOCK_SIZE;
}
trace_migration_block_state_pending(pending);
/* We don't do postcopy */
*must_precopy += 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 = BLK_MIG_BLOCK_SIZE;
do {
addr = qemu_get_be64(f);
flags = addr & (BDRV_SECTOR_SIZE - 1);
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_activate(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 <= BLK_MIG_BLOCK_SIZE &&
BLK_MIG_BLOCK_SIZE % bdi.cluster_size == 0) {
cluster_size = bdi.cluster_size;
} else {
cluster_size = BLK_MIG_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(BLK_MIG_BLOCK_SIZE);
qemu_get_buffer(f, buf, BLK_MIG_BLOCK_SIZE);
for (i = 0; i < BLK_MIG_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 < BLK_MIG_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, cluster_size, cur_buf,
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: 0x%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,
.state_pending_exact = block_state_pending,
.state_pending_estimate = block_state_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("block", 0, 1, &savevm_block_handlers,
&block_mig_state);
}
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