block-migration.c - third_party/qemu - Git at Google

 /*
  * 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 "qemu-queue.h"
 #include "monitor.h"
 #include "block-migration.h"
 #include <assert.h>

 #define BLOCK_SIZE (BDRV_SECTORS_PER_DIRTY_CHUNK << 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 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 BlkMigDevState {
     BlockDriverState *bs;
     int bulk_completed;
     int shared_base;
     int64_t cur_sector;
     int64_t completed_sectors;
     int64_t total_sectors;
     int64_t dirty;
     QSIMPLEQ_ENTRY(BlkMigDevState) entry;
 } BlkMigDevState;

 typedef struct BlkMigBlock {
     uint8_t *buf;
     BlkMigDevState *bmds;
     int64_t sector;
     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;
 } 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 void blk_mig_read_cb(void *opaque, int ret)
 {
     BlkMigBlock *blk = opaque;

     blk->ret = ret;

     QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);

     block_mig_state.submitted--;
     block_mig_state.read_done++;
     assert(block_mig_state.submitted >= 0);
 }

 static int mig_save_device_bulk(Monitor *mon, QEMUFile *f,
                                 BlkMigDevState *bmds, int is_async)
 {
     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 = qemu_malloc(sizeof(BlkMigBlock));
     blk->buf = qemu_malloc(BLOCK_SIZE);
     blk->bmds = bmds;
     blk->sector = cur_sector;

     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);

         blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
                                     nr_sectors, blk_mig_read_cb, blk);
         if (!blk->aiocb) {
             goto error;
         }
         block_mig_state.submitted++;
     } else {
         if (bdrv_read(bs, cur_sector, blk->buf, nr_sectors) < 0) {
             goto error;
         }
         blk_send(f, blk);

         qemu_free(blk->buf);
         qemu_free(blk);
     }

     bdrv_reset_dirty(bs, cur_sector, nr_sectors);
     bmds->cur_sector = cur_sector + nr_sectors;

     return (bmds->cur_sector >= total_sectors);

 error:
     monitor_printf(mon, "Error reading sector %" PRId64 "\n", cur_sector);
     qemu_file_set_error(f);
     qemu_free(blk->buf);
     qemu_free(blk);
     return 0;
 }

 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);
     }
 }

 static void init_blk_migration(Monitor *mon, QEMUFile *f)
 {
     BlkMigDevState *bmds;
     BlockDriverState *bs;
     int64_t sectors;

     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;

     for (bs = bdrv_first; bs != NULL; bs = bs->next) {
         if (bs->type == BDRV_TYPE_HD) {
             sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
             if (sectors == 0) {
                 continue;
             }

             bmds = qemu_mallocz(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;

             block_mig_state.total_sector_sum += sectors;

             if (bmds->shared_base) {
                 monitor_printf(mon, "Start migration for %s with shared base "
                                     "image\n",
                                bs->device_name);
             } else {
                 monitor_printf(mon, "Start full migration for %s\n",
                                bs->device_name);
             }

             QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
         }
     }
 }

 static int blk_mig_save_bulked_block(Monitor *mon, QEMUFile *f, int is_async)
 {
     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(mon, f, bmds, is_async) == 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;
         }
     }

     progress = completed_sector_sum * 100 / block_mig_state.total_sector_sum;
     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);
         monitor_printf(mon, "Completed %d %%\r", progress);
         monitor_flush(mon);
     }

     return ret;
 }

 #define MAX_NUM_BLOCKS 4

 static void blk_mig_save_dirty_blocks(Monitor *mon, QEMUFile *f)
 {
     BlkMigDevState *bmds;
     BlkMigBlock blk;
     int64_t sector;

     blk.buf = qemu_malloc(BLOCK_SIZE);

     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
         for (sector = 0; sector < bmds->cur_sector;) {
             if (bdrv_get_dirty(bmds->bs, sector)) {
                 if (bdrv_read(bmds->bs, sector, blk.buf,
                               BDRV_SECTORS_PER_DIRTY_CHUNK) < 0) {
                     monitor_printf(mon, "Error reading sector %" PRId64 "\n",
                                    sector);
                     qemu_file_set_error(f);
                     qemu_free(blk.buf);
                     return;
                 }
                 blk.bmds = bmds;
                 blk.sector = sector;
                 blk_send(f, &blk);

                 bdrv_reset_dirty(bmds->bs, sector,
                                  BDRV_SECTORS_PER_DIRTY_CHUNK);
             }
             sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
         }
     }

     qemu_free(blk.buf);
 }

 static void flush_blks(QEMUFile* f)
 {
     BlkMigBlock *blk;

     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) {
             qemu_file_set_error(f);
             break;
         }
         blk_send(f, blk);

         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
         qemu_free(blk->buf);
         qemu_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);
 }

 static int is_stage2_completed(void)
 {
     BlkMigDevState *bmds;

     if (block_mig_state.submitted > 0) {
         return 0;
     }

     QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
         if (bmds->bulk_completed == 0) {
             return 0;
         }
     }

     return 1;
 }

 static void blk_mig_cleanup(Monitor *mon)
 {
     BlkMigDevState *bmds;
     BlkMigBlock *blk;

     while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
         qemu_free(bmds);
     }

     while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
         QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
         qemu_free(blk->buf);
         qemu_free(blk);
     }

     set_dirty_tracking(0);

     monitor_printf(mon, "\n");
 }

 static int block_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
 {
     dprintf("Enter save live stage %d submitted %d transferred %d\n",
             stage, block_mig_state.submitted, block_mig_state.transferred);

     if (stage < 0) {
         blk_mig_cleanup(mon);
         return 0;
     }

     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(mon, f);

         /* start track dirty blocks */
         set_dirty_tracking(1);
     }

     flush_blks(f);

     if (qemu_file_has_error(f)) {
         blk_mig_cleanup(mon);
         return 0;
     }

     /* control the rate of transfer */
     while ((block_mig_state.submitted +
             block_mig_state.read_done) * BLOCK_SIZE <
            qemu_file_get_rate_limit(f)) {
         if (blk_mig_save_bulked_block(mon, f, 1) == 0) {
             /* no more bulk blocks for now */
             break;
         }
     }

     flush_blks(f);

     if (qemu_file_has_error(f)) {
         blk_mig_cleanup(mon);
         return 0;
     }

     if (stage == 3) {
         while (blk_mig_save_bulked_block(mon, f, 0) != 0) {
             /* empty */
         }

         blk_mig_save_dirty_blocks(mon, f);
         blk_mig_cleanup(mon);

         /* report completion */
         qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);

         if (qemu_file_has_error(f)) {
             return 0;
         }

         monitor_printf(mon, "Block 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)
 {
     static int banner_printed;
     int len, flags;
     char device_name[256];
     int64_t addr;
     BlockDriverState *bs;
     uint8_t *buf;

     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;
             }

             buf = qemu_malloc(BLOCK_SIZE);

             qemu_get_buffer(f, buf, BLOCK_SIZE);
             bdrv_write(bs, addr, buf, BDRV_SECTORS_PER_DIRTY_CHUNK);

             qemu_free(buf);
         } 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 flags\n");
             return -EINVAL;
         }
         if (qemu_file_has_error(f)) {
             return -EIO;
         }
     } while (!(flags & BLK_MIG_FLAG_EOS));

     return 0;
 }

 static void block_set_params(int blk_enable, int shared_base, void *opaque)
 {
     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;
 }

 void blk_mig_init(void)
 {
     QSIMPLEQ_INIT(&block_mig_state.bmds_list);
     QSIMPLEQ_INIT(&block_mig_state.blk_list);

     register_savevm_live("block", 0, 1, block_set_params, block_save_live,
                          NULL, block_load, &block_mig_state);
 }
	/*
	* 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 "qemu-queue.h"
	#include "monitor.h"
	#include "block-migration.h"
	#include <assert.h>

	#define BLOCK_SIZE (BDRV_SECTORS_PER_DIRTY_CHUNK << 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 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 BlkMigDevState {
	BlockDriverState *bs;
	int bulk_completed;
	int shared_base;
	int64_t cur_sector;
	int64_t completed_sectors;
	int64_t total_sectors;
	int64_t dirty;
	QSIMPLEQ_ENTRY(BlkMigDevState) entry;
	} BlkMigDevState;

	typedef struct BlkMigBlock {
	uint8_t *buf;
	BlkMigDevState *bmds;
	int64_t sector;
	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;
	} 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 void blk_mig_read_cb(void *opaque, int ret)
	{
	BlkMigBlock *blk = opaque;

	blk->ret = ret;

	QSIMPLEQ_INSERT_TAIL(&block_mig_state.blk_list, blk, entry);

	block_mig_state.submitted--;
	block_mig_state.read_done++;
	assert(block_mig_state.submitted >= 0);
	}

	static int mig_save_device_bulk(Monitor mon, QEMUFile f,
	BlkMigDevState *bmds, int is_async)
	{
	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 = qemu_malloc(sizeof(BlkMigBlock));
	blk->buf = qemu_malloc(BLOCK_SIZE);
	blk->bmds = bmds;
	blk->sector = cur_sector;

	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);

	blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
	nr_sectors, blk_mig_read_cb, blk);
	if (!blk->aiocb) {
	goto error;
	}
	block_mig_state.submitted++;
	} else {
	if (bdrv_read(bs, cur_sector, blk->buf, nr_sectors) < 0) {
	goto error;
	}
	blk_send(f, blk);

	qemu_free(blk->buf);
	qemu_free(blk);
	}

	bdrv_reset_dirty(bs, cur_sector, nr_sectors);
	bmds->cur_sector = cur_sector + nr_sectors;

	return (bmds->cur_sector >= total_sectors);

	error:
	monitor_printf(mon, "Error reading sector %" PRId64 "\n", cur_sector);
	qemu_file_set_error(f);
	qemu_free(blk->buf);
	qemu_free(blk);
	return 0;
	}

	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);
	}
	}

	static void init_blk_migration(Monitor mon, QEMUFile f)
	{
	BlkMigDevState *bmds;
	BlockDriverState *bs;
	int64_t sectors;

	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;

	for (bs = bdrv_first; bs != NULL; bs = bs->next) {
	if (bs->type == BDRV_TYPE_HD) {
	sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
	if (sectors == 0) {
	continue;
	}

	bmds = qemu_mallocz(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;

	block_mig_state.total_sector_sum += sectors;

	if (bmds->shared_base) {
	monitor_printf(mon, "Start migration for %s with shared base "
	"image\n",
	bs->device_name);
	} else {
	monitor_printf(mon, "Start full migration for %s\n",
	bs->device_name);
	}

	QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
	}
	}
	}

	static int blk_mig_save_bulked_block(Monitor mon, QEMUFile f, int is_async)
	{
	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(mon, f, bmds, is_async) == 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;
	}
	}

	progress = completed_sector_sum * 100 / block_mig_state.total_sector_sum;
	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);
	monitor_printf(mon, "Completed %d %%\r", progress);
	monitor_flush(mon);
	}

	return ret;
	}

	#define MAX_NUM_BLOCKS 4

	static void blk_mig_save_dirty_blocks(Monitor mon, QEMUFile f)
	{
	BlkMigDevState *bmds;
	BlkMigBlock blk;
	int64_t sector;

	blk.buf = qemu_malloc(BLOCK_SIZE);

	QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
	for (sector = 0; sector < bmds->cur_sector;) {
	if (bdrv_get_dirty(bmds->bs, sector)) {
	if (bdrv_read(bmds->bs, sector, blk.buf,
	BDRV_SECTORS_PER_DIRTY_CHUNK) < 0) {
	monitor_printf(mon, "Error reading sector %" PRId64 "\n",
	sector);
	qemu_file_set_error(f);
	qemu_free(blk.buf);
	return;
	}
	blk.bmds = bmds;
	blk.sector = sector;
	blk_send(f, &blk);

	bdrv_reset_dirty(bmds->bs, sector,
	BDRV_SECTORS_PER_DIRTY_CHUNK);
	}
	sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
	}
	}

	qemu_free(blk.buf);
	}

	static void flush_blks(QEMUFile* f)
	{
	BlkMigBlock *blk;

	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) {
	qemu_file_set_error(f);
	break;
	}
	blk_send(f, blk);

	QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
	qemu_free(blk->buf);
	qemu_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);
	}

	static int is_stage2_completed(void)
	{
	BlkMigDevState *bmds;

	if (block_mig_state.submitted > 0) {
	return 0;
	}

	QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
	if (bmds->bulk_completed == 0) {
	return 0;
	}
	}

	return 1;
	}

	static void blk_mig_cleanup(Monitor *mon)
	{
	BlkMigDevState *bmds;
	BlkMigBlock *blk;

	while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {
	QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);
	qemu_free(bmds);
	}

	while ((blk = QSIMPLEQ_FIRST(&block_mig_state.blk_list)) != NULL) {
	QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
	qemu_free(blk->buf);
	qemu_free(blk);
	}

	set_dirty_tracking(0);

	monitor_printf(mon, "\n");
	}

	static int block_save_live(Monitor mon, QEMUFile f, int stage, void *opaque)
	{
	dprintf("Enter save live stage %d submitted %d transferred %d\n",
	stage, block_mig_state.submitted, block_mig_state.transferred);

	if (stage < 0) {
	blk_mig_cleanup(mon);
	return 0;
	}

	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(mon, f);

	/* start track dirty blocks */
	set_dirty_tracking(1);
	}

	flush_blks(f);

	if (qemu_file_has_error(f)) {
	blk_mig_cleanup(mon);
	return 0;
	}

	/* control the rate of transfer */
	while ((block_mig_state.submitted +
	block_mig_state.read_done) * BLOCK_SIZE <
	qemu_file_get_rate_limit(f)) {
	if (blk_mig_save_bulked_block(mon, f, 1) == 0) {
	/* no more bulk blocks for now */
	break;
	}
	}

	flush_blks(f);

	if (qemu_file_has_error(f)) {
	blk_mig_cleanup(mon);
	return 0;
	}

	if (stage == 3) {
	while (blk_mig_save_bulked_block(mon, f, 0) != 0) {
	/* empty */
	}

	blk_mig_save_dirty_blocks(mon, f);
	blk_mig_cleanup(mon);

	/* report completion */
	qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) \| BLK_MIG_FLAG_PROGRESS);

	if (qemu_file_has_error(f)) {
	return 0;
	}

	monitor_printf(mon, "Block 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)
	{
	static int banner_printed;
	int len, flags;
	char device_name[256];
	int64_t addr;
	BlockDriverState *bs;
	uint8_t *buf;

	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;
	}

	buf = qemu_malloc(BLOCK_SIZE);

	qemu_get_buffer(f, buf, BLOCK_SIZE);
	bdrv_write(bs, addr, buf, BDRV_SECTORS_PER_DIRTY_CHUNK);

	qemu_free(buf);
	} 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 flags\n");
	return -EINVAL;
	}
	if (qemu_file_has_error(f)) {
	return -EIO;
	}
	} while (!(flags & BLK_MIG_FLAG_EOS));

	return 0;
	}

	static void block_set_params(int blk_enable, int shared_base, void *opaque)
	{
	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;
	}

	void blk_mig_init(void)
	{
	QSIMPLEQ_INIT(&block_mig_state.bmds_list);
	QSIMPLEQ_INIT(&block_mig_state.blk_list);

	register_savevm_live("block", 0, 1, block_set_params, block_save_live,
	NULL, block_load, &block_mig_state);
	}