X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=block-migration.c;h=0936c7d5ea347de19d37afe4ae7d9956381bc6d7;hb=3acccfc67d3aa4611142e2171337c7c494b52efb;hp=f6fac73961571d74e2db267a87601488ce0947a3;hpb=d11ecd3dd54fec1eaf132300701b219723256c49;p=qemu.git

diff --git a/block-migration.c b/block-migration.c
index f6fac7396..0936c7d5e 100644
--- a/block-migration.c
+++ b/block-migration.c
@@ -14,26 +14,29 @@
 #include "qemu-common.h"
 #include "block_int.h"
 #include "hw/hw.h"
+#include "qemu-queue.h"
+#include "qemu-timer.h"
+#include "monitor.h"
 #include "block-migration.h"
+#include "migration.h"
+#include "blockdev.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, ...) \
+#define DPRINTF(fmt, ...) \
     do { printf("blk_migration: " fmt, ## __VA_ARGS__); } while (0)
 #else
-#define dprintf(fmt, ...) \
+#define DPRINTF(fmt, ...) \
     do { } while (0)
 #endif
 
@@ -41,160 +44,187 @@ typedef struct BlkMigDevState {
     BlockDriverState *bs;
     int bulk_completed;
     int shared_base;
-    struct BlkMigDevState *next;
     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;
-    struct BlkMigBlock *next;
+    QSIMPLEQ_ENTRY(BlkMigBlock) entry;
 } BlkMigBlock;
 
 typedef struct BlkMigState {
-    int bulk_completed;
     int blk_enable;
     int shared_base;
-    int no_dirty;
-    QEMUFile *load_file;
-    BlkMigDevState *bmds_first;
-    BlkMigBlock *first_blk;
-    BlkMigBlock *last_blk;
+    QSIMPLEQ_HEAD(bmds_list, BlkMigDevState) bmds_list;
+    QSIMPLEQ_HEAD(blk_list, BlkMigBlock) blk_list;
     int submitted;
     int read_done;
     int transferred;
-    int64_t print_completion;
+    int64_t total_sector_sum;
+    int prev_progress;
+    int bulk_completed;
+    long double total_time;
+    long double prev_time_offset;
+    int reads;
 } BlkMigState;
 
 static BlkMigState block_mig_state;
 
-static void blk_mig_read_cb(void *opaque, int ret)
+static void blk_send(QEMUFile *f, BlkMigBlock * blk)
 {
-    BlkMigBlock *blk = opaque;
+    int len;
 
-    blk->ret = ret;
+    /* sector number and flags */
+    qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
+                     | BLK_MIG_FLAG_DEVICE_BLOCK);
 
-    /* insert at the end */
-    if (block_mig_state.last_blk == NULL) {
-        block_mig_state.first_blk = blk;
-        block_mig_state.last_blk = blk;
-    } else {
-        block_mig_state.last_blk->next = blk;
-        block_mig_state.last_blk = blk;
-    }
+    /* 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);
 
-    block_mig_state.submitted--;
-    block_mig_state.read_done++;
-    assert(block_mig_state.submitted >= 0);
+    qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
 }
 
-static int mig_read_device_bulk(QEMUFile *f, BlkMigDevState *bms)
+int blk_mig_active(void)
 {
-    int nr_sectors;
-    int64_t total_sectors, cur_sector = 0;
-    BlockDriverState *bs = bms->bs;
-    BlkMigBlock *blk;
-
-    blk = qemu_malloc(sizeof(BlkMigBlock));
-    blk->buf = qemu_malloc(BLOCK_SIZE);
+    return !QSIMPLEQ_EMPTY(&block_mig_state.bmds_list);
+}
 
-    cur_sector = bms->cur_sector;
-    total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
+uint64_t blk_mig_bytes_transferred(void)
+{
+    BlkMigDevState *bmds;
+    uint64_t sum = 0;
 
-    if (bms->shared_base) {
-        while (cur_sector < bms->total_sectors &&
-               !bdrv_is_allocated(bms->bs, cur_sector,
-                                  MAX_IS_ALLOCATED_SEARCH, &nr_sectors)) {
-            cur_sector += nr_sectors;
-        }
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        sum += bmds->completed_sectors;
     }
+    return sum << BDRV_SECTOR_BITS;
+}
 
-    if (cur_sector >= total_sectors) {
-        bms->cur_sector = total_sectors;
-        qemu_free(blk->buf);
-        qemu_free(blk);
-        return 1;
-    }
+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;
 
-    if (cur_sector >= block_mig_state.print_completion) {
-        printf("Completed %" PRId64 " %%\r", cur_sector * 100 / total_sectors);
-        fflush(stdout);
-        block_mig_state.print_completion +=
-            (BDRV_SECTORS_PER_DIRTY_CHUNK * 10000);
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        sum += bmds->total_sectors;
     }
+    return sum << BDRV_SECTOR_BITS;
+}
 
-    /* we are going to transfer a full block even if it is not allocated */
-    nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
+static inline long double compute_read_bwidth(void)
+{
+    assert(block_mig_state.total_time != 0);
+    return (block_mig_state.reads / block_mig_state.total_time) * BLOCK_SIZE;
+}
 
-    cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
+static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector)
+{
+    int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
 
-    if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
-        nr_sectors = (total_sectors - cur_sector);
+    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;
     }
+}
 
-    bms->cur_sector = cur_sector + nr_sectors;
-    blk->sector = cur_sector;
-    blk->bmds = bms;
-    blk->next = NULL;
+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;
+    }
+}
 
-    blk->iov.iov_base = blk->buf;
-    blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;
-    qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);
+static void alloc_aio_bitmap(BlkMigDevState *bmds)
+{
+    BlockDriverState *bs = bmds->bs;
+    int64_t bitmap_size;
 
-    blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,
-                                nr_sectors, blk_mig_read_cb, blk);
+    bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS) +
+            BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;
+    bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
 
-    if (!blk->aiocb) {
-        printf("Error reading sector %" PRId64 "\n", cur_sector);
-        qemu_free(blk->buf);
-        qemu_free(blk);
-        return 0;
-    }
+    bmds->aio_bitmap = qemu_mallocz(bitmap_size);
+}
 
-    bdrv_reset_dirty(bms->bs, cur_sector, nr_sectors);
-    block_mig_state.submitted++;
+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.reads++;
+    block_mig_state.total_time += (curr_time - block_mig_state.prev_time_offset);
+    block_mig_state.prev_time_offset = curr_time;
 
-    return (bms->cur_sector >= total_sectors);
+    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)
+static int mig_save_device_bulk(Monitor *mon, QEMUFile *f,
+                                BlkMigDevState *bmds)
 {
-    int len, nr_sectors;
-    int64_t total_sectors = bmds->total_sectors, cur_sector = 0;
-    uint8_t *tmp_buf = NULL;
+    int64_t total_sectors = bmds->total_sectors;
+    int64_t cur_sector = bmds->cur_sector;
     BlockDriverState *bs = bmds->bs;
-
-    tmp_buf = qemu_malloc(BLOCK_SIZE);
-
-    cur_sector = bmds->cur_sector;
+    BlkMigBlock *blk;
+    int nr_sectors;
 
     if (bmds->shared_base) {
-        while (cur_sector < bmds->total_sectors &&
-               !bdrv_is_allocated(bmds->bs, cur_sector,
-                                  MAX_IS_ALLOCATED_SEARCH, &nr_sectors)) {
+        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 = total_sectors;
-        qemu_free(tmp_buf);
+        bmds->cur_sector = bmds->completed_sectors = total_sectors;
         return 1;
     }
 
-    if (cur_sector >= block_mig_state.print_completion) {
-        printf("Completed %" PRId64 " %%\r", cur_sector * 100 / total_sectors);
-        fflush(stdout);
-        block_mig_state.print_completion +=
-            (BDRV_SECTORS_PER_DIRTY_CHUNK * 10000);
-    }
+    bmds->completed_sectors = cur_sector;
 
     cur_sector &= ~((int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK - 1);
 
@@ -202,174 +232,253 @@ static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds)
     nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
 
     if (total_sectors - cur_sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {
-        nr_sectors = (total_sectors - cur_sector);
+        nr_sectors = total_sectors - cur_sector;
     }
 
-    if (bdrv_read(bs, cur_sector, tmp_buf, nr_sectors) < 0) {
-        printf("Error reading sector %" PRId64 "\n", cur_sector);
-    }
+    blk = qemu_malloc(sizeof(BlkMigBlock));
+    blk->buf = qemu_malloc(BLOCK_SIZE);
+    blk->bmds = bmds;
+    blk->sector = cur_sector;
+    blk->nr_sectors = nr_sectors;
 
-    bdrv_reset_dirty(bs, cur_sector, 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);
 
-    /* sector number and flags */
-    qemu_put_be64(f, (cur_sector << BDRV_SECTOR_BITS)
-                     | BLK_MIG_FLAG_DEVICE_BLOCK);
+    if (block_mig_state.submitted == 0) {
+        block_mig_state.prev_time_offset = qemu_get_clock_ns(rt_clock);
+    }
 
-    /* device name */
-    len = strlen(bs->device_name);
-    qemu_put_byte(f, len);
-    qemu_put_buffer(f, (uint8_t *)bs->device_name, len);
+    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++;
+
+    bdrv_reset_dirty(bs, cur_sector, nr_sectors);
+    bmds->cur_sector = cur_sector + nr_sectors;
 
-    qemu_put_buffer(f, tmp_buf, BLOCK_SIZE);
+    return (bmds->cur_sector >= total_sectors);
 
-    bmds->cur_sector = cur_sector + BDRV_SECTORS_PER_DIRTY_CHUNK;
+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;
+}
 
-    qemu_free(tmp_buf);
+static void set_dirty_tracking(int enable)
+{
+    BlkMigDevState *bmds;
 
-    return (bmds->cur_sector >= total_sectors);
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        bdrv_set_dirty_tracking(bmds->bs, enable);
+    }
 }
 
-static void send_blk(QEMUFile *f, BlkMigBlock * blk)
+static void init_blk_migration_it(void *opaque, BlockDriverState *bs)
 {
-    int len;
+    Monitor *mon = opaque;
+    BlkMigDevState *bmds;
+    int64_t sectors;
 
-    /* sector number and flags */
-    qemu_put_be64(f, (blk->sector << BDRV_SECTOR_BITS)
-                     | BLK_MIG_FLAG_DEVICE_BLOCK);
+    if (!bdrv_is_read_only(bs)) {
+        sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
+        if (sectors <= 0) {
+            return;
+        }
 
-    /* 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);
+        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;
+        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) {
+            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);
+        }
 
-    qemu_put_buffer(f, blk->buf, BLOCK_SIZE);
+        QSIMPLEQ_INSERT_TAIL(&block_mig_state.bmds_list, bmds, entry);
+    }
 }
 
-static void blk_mig_save_dev_info(QEMUFile *f, BlkMigDevState *bmds)
+static void init_blk_migration(Monitor *mon, 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;
+    block_mig_state.total_time = 0;
+    block_mig_state.reads = 0;
+
+    bdrv_iterate(init_blk_migration_it, mon);
 }
 
-static void set_dirty_tracking(int enable)
+static int blk_mig_save_bulked_block(Monitor *mon, QEMUFile *f)
 {
+    int64_t completed_sector_sum = 0;
     BlkMigDevState *bmds;
-    for (bmds = block_mig_state.bmds_first; bmds != NULL; bmds = bmds->next) {
-        bdrv_set_dirty_tracking(bmds->bs, enable);
+    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) == 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;
+        }
     }
-}
 
-static void init_blk_migration(QEMUFile *f)
-{
-    BlkMigDevState **pbmds, *bmds;
-    BlockDriverState *bs;
+    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);
+        monitor_printf(mon, "Completed %d %%\r", progress);
+        monitor_flush(mon);
+    }
 
-    for (bs = bdrv_first; bs != NULL; bs = bs->next) {
-        if (bs->type == BDRV_TYPE_HD) {
-            bmds = qemu_mallocz(sizeof(BlkMigDevState));
-            bmds->bs = bs;
-            bmds->bulk_completed = 0;
-            bmds->total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS;
-            bmds->shared_base = block_mig_state.shared_base;
-
-            if (bmds->shared_base) {
-                printf("Start migration for %s with shared base image\n",
-                       bs->device_name);
-            } else {
-                printf("Start full migration for %s\n", bs->device_name);
-            }
+    return ret;
+}
 
-            /* insert at the end */
-            pbmds = &block_mig_state.bmds_first;
-            while (*pbmds != NULL) {
-                pbmds = &(*pbmds)->next;
-            }
-            *pbmds = bmds;
+static void blk_mig_reset_dirty_cursor(void)
+{
+    BlkMigDevState *bmds;
 
-            blk_mig_save_dev_info(f, bmds);
-        }
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        bmds->cur_dirty = 0;
     }
 }
 
-static int blk_mig_save_bulked_block(QEMUFile *f, int is_async)
+static int mig_save_device_dirty(Monitor *mon, QEMUFile *f,
+                                 BlkMigDevState *bmds, int is_async)
 {
-    BlkMigDevState *bmds;
+    BlkMigBlock *blk;
+    int64_t total_sectors = bmds->total_sectors;
+    int64_t sector;
+    int nr_sectors;
+
+    for (sector = bmds->cur_dirty; sector < bmds->total_sectors;) {
+        if (bmds_aio_inflight(bmds, sector)) {
+            qemu_aio_flush();
+        }
+        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 = qemu_malloc(sizeof(BlkMigBlock));
+            blk->buf = qemu_malloc(BLOCK_SIZE);
+            blk->bmds = bmds;
+            blk->sector = sector;
+            blk->nr_sectors = nr_sectors;
 
-    for (bmds = block_mig_state.bmds_first; bmds != NULL; bmds = bmds->next) {
-        if (bmds->bulk_completed == 0) {
             if (is_async) {
-                if (mig_read_device_bulk(f, bmds) == 1) {
-                    /* completed bulk section for this device */
-                    bmds->bulk_completed = 1;
+                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);
+                if (!blk->aiocb) {
+                    goto error;
                 }
+                block_mig_state.submitted++;
+                bmds_set_aio_inflight(bmds, sector, nr_sectors, 1);
             } else {
-                if (mig_save_device_bulk(f, bmds) == 1) {
-                    /* completed bulk section for this device */
-                    bmds->bulk_completed = 1;
+                if (bdrv_read(bmds->bs, sector, blk->buf,
+                              nr_sectors) < 0) {
+                    goto error;
                 }
+                blk_send(f, blk);
+
+                qemu_free(blk->buf);
+                qemu_free(blk);
             }
-            return 1;
+
+            bdrv_reset_dirty(bmds->bs, sector, nr_sectors);
+            break;
         }
+        sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
+        bmds->cur_dirty = sector;
     }
 
-    /* we reached here means bulk is completed */
-    block_mig_state.bulk_completed = 1;
+    return (bmds->cur_dirty >= bmds->total_sectors);
 
+error:
+    monitor_printf(mon, "Error reading sector %" PRId64 "\n", sector);
+    qemu_file_set_error(f);
+    qemu_free(blk->buf);
+    qemu_free(blk);
     return 0;
 }
 
-#define MAX_NUM_BLOCKS 4
-
-static void blk_mig_save_dirty_blocks(QEMUFile *f)
+static int blk_mig_save_dirty_block(Monitor *mon, QEMUFile *f, int is_async)
 {
     BlkMigDevState *bmds;
-    uint8_t *buf;
-    int64_t sector;
-    int len;
-
-    buf = qemu_malloc(BLOCK_SIZE);
+    int ret = 0;
 
-    for (bmds = block_mig_state.bmds_first; bmds != NULL; bmds = bmds->next) {
-        for (sector = 0; sector < bmds->cur_sector;) {
-            if (bdrv_get_dirty(bmds->bs, sector)) {
-                if (bdrv_read(bmds->bs, sector, buf,
-                              BDRV_SECTORS_PER_DIRTY_CHUNK) < 0) {
-                    /* FIXME: add error handling */
-                }
-
-                /* sector number and flags */
-                qemu_put_be64(f, (sector << BDRV_SECTOR_BITS)
-                                 | BLK_MIG_FLAG_DEVICE_BLOCK);
-
-                /* device name */
-                len = strlen(bmds->bs->device_name);
-                qemu_put_byte(f, len);
-                qemu_put_buffer(f, (uint8_t *)bmds->bs->device_name, len);
-
-                qemu_put_buffer(f, buf, BLOCK_SIZE);
-
-                bdrv_reset_dirty(bmds->bs, sector,
-                                 BDRV_SECTORS_PER_DIRTY_CHUNK);
-            }
-            sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        if (mig_save_device_dirty(mon, f, bmds, is_async) == 0) {
+            ret = 1;
+            break;
         }
     }
 
-    qemu_free(buf);
+    return ret;
 }
 
 static void flush_blks(QEMUFile* f)
 {
-    BlkMigBlock *blk, *next;
+    BlkMigBlock *blk;
 
-    dprintf("%s Enter submitted %d read_done %d transferred %d\n",
+    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);
 
-    for (blk = block_mig_state.first_blk;
-         blk != NULL && !qemu_file_rate_limit(f);
-         blk = next) {
-        send_blk(f, blk);
+    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);
 
-        next = blk->next;
+        QSIMPLEQ_REMOVE_HEAD(&block_mig_state.blk_list, entry);
         qemu_free(blk->buf);
         qemu_free(blk);
 
@@ -377,39 +486,84 @@ static void flush_blks(QEMUFile* f)
         block_mig_state.transferred++;
         assert(block_mig_state.read_done >= 0);
     }
-    block_mig_state.first_blk = blk;
 
-    if (block_mig_state.first_blk == NULL) {
-        block_mig_state.last_blk = NULL;
-    }
-
-    dprintf("%s Exit submitted %d read_done %d transferred %d\n", __FUNCTION__,
+    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)
+static int64_t get_remaining_dirty(void)
 {
     BlkMigDevState *bmds;
+    int64_t dirty = 0;
 
-    if (block_mig_state.submitted > 0) {
-        return 0;
+    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
+        dirty += bdrv_get_dirty_count(bmds->bs);
     }
 
-    for (bmds = block_mig_state.bmds_first; bmds != NULL; bmds = bmds->next) {
-        if (bmds->bulk_completed == 0) {
-            return 0;
+    return dirty * BLOCK_SIZE;
+}
+
+static int is_stage2_completed(void)
+{
+    int64_t remaining_dirty;
+    long double bwidth;
+
+    if (block_mig_state.bulk_completed == 1) {
+
+        remaining_dirty = get_remaining_dirty();
+        if (remaining_dirty == 0) {
+            return 1;
+        }
+
+        bwidth = compute_read_bwidth();
+
+        if ((remaining_dirty / bwidth) <=
+            migrate_max_downtime()) {
+            /* finish stage2 because we think that we can finish remaing work
+               below max_downtime */
+
+            return 1;
         }
     }
 
-    return 1;
+    return 0;
+}
+
+static void blk_mig_cleanup(Monitor *mon)
+{
+    BlkMigDevState *bmds;
+    BlkMigBlock *blk;
+
+    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));
+        qemu_free(bmds->aio_bitmap);
+        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);
+    }
+
+    monitor_printf(mon, "\n");
 }
 
-static int block_save_live(QEMUFile *f, int stage, void *opaque)
+static int block_save_live(Monitor *mon, QEMUFile *f, int stage, void *opaque)
 {
-    dprintf("Enter save live stage %d submitted %d transferred %d\n",
+    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);
@@ -417,7 +571,7 @@ static int block_save_live(QEMUFile *f, int stage, void *opaque)
     }
 
     if (stage == 1) {
-        init_blk_migration(f);
+        init_blk_migration(mon, f);
 
         /* start track dirty blocks */
         set_dirty_tracking(1);
@@ -425,29 +579,56 @@ static int block_save_live(QEMUFile *f, int stage, void *opaque)
 
     flush_blks(f);
 
-    /* control the rate of transfer */
-    while ((block_mig_state.submitted +
-            block_mig_state.read_done) * BLOCK_SIZE <
-           qemu_file_get_rate_limit(f)) {
-        if (blk_mig_save_bulked_block(f, 1) == 0) {
-            /* no more bulk blocks for now */
-            break;
-        }
+    if (qemu_file_has_error(f)) {
+        blk_mig_cleanup(mon);
+        return 0;
     }
 
-    flush_blks(f);
+    blk_mig_reset_dirty_cursor();
+
+    if (stage == 2) {
+        /* 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(mon, f) == 0) {
+                    /* finished saving bulk on all devices */
+                    block_mig_state.bulk_completed = 1;
+                }
+            } else {
+                if (blk_mig_save_dirty_block(mon, f, 1) == 0) {
+                    /* no more dirty blocks */
+                    break;
+                }
+            }
+        }
 
-    if (stage == 3) {
-        while (blk_mig_save_bulked_block(f, 0) != 0) {
-            /* empty */
+        flush_blks(f);
+
+        if (qemu_file_has_error(f)) {
+            blk_mig_cleanup(mon);
+            return 0;
         }
+    }
 
-        blk_mig_save_dirty_blocks(f);
+    if (stage == 3) {
+        /* we know for sure that save bulk is completed and
+           all async read completed */
+        assert(block_mig_state.submitted == 0);
+
+        while (blk_mig_save_dirty_block(mon, f, 0) != 0);
+        blk_mig_cleanup(mon);
 
-        /* stop track dirty blocks */
-        set_dirty_tracking(0);
+        /* report completion */
+        qemu_put_be64(f, (100 << BDRV_SECTOR_BITS) | BLK_MIG_FLAG_PROGRESS);
+
+        if (qemu_file_has_error(f)) {
+            return 0;
+        }
 
-        printf("\nBlock migration completed\n");
+        monitor_printf(mon, "Block migration completed\n");
     }
 
     qemu_put_be64(f, BLK_MIG_FLAG_EOS);
@@ -457,11 +638,14 @@ static int block_save_live(QEMUFile *f, int stage, void *opaque)
 
 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;
+    BlockDriverState *bs, *bs_prev = NULL;
     uint8_t *buf;
+    int64_t total_sectors = 0;
+    int nr_sectors;
 
     do {
         addr = qemu_get_be64(f);
@@ -470,28 +654,58 @@ static int block_load(QEMUFile *f, void *opaque, int version_id)
         addr >>= BDRV_SECTOR_BITS;
 
         if (flags & BLK_MIG_FLAG_DEVICE_BLOCK) {
+            int ret;
             /* 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);
+            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;
+                }
+            }
 
-            qemu_get_buffer(f, buf, BLOCK_SIZE);
-            if (bs != NULL) {
-                bdrv_write(bs, addr, buf, BDRV_SECTORS_PER_DIRTY_CHUNK);
+            if (total_sectors - addr < BDRV_SECTORS_PER_DIRTY_CHUNK) {
+                nr_sectors = total_sectors - addr;
             } else {
-                printf("Error unknown block device %s\n", device_name);
-                /* FIXME: add error handling */
+                nr_sectors = BDRV_SECTORS_PER_DIRTY_CHUNK;
             }
 
+            buf = qemu_malloc(BLOCK_SIZE);
+
+            qemu_get_buffer(f, buf, BLOCK_SIZE);
+            ret = bdrv_write(bs, addr, buf, nr_sectors);
+
             qemu_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)) {
-            printf("Unknown flags\n");
-            /* FIXME: add error handling */
+            fprintf(stderr, "Unknown flags\n");
+            return -EINVAL;
+        }
+        if (qemu_file_has_error(f)) {
+            return -EIO;
         }
     } while (!(flags & BLK_MIG_FLAG_EOS));
 
@@ -507,21 +721,11 @@ static void block_set_params(int blk_enable, int shared_base, void *opaque)
     block_mig_state.blk_enable |= shared_base;
 }
 
-void blk_mig_info(void)
-{
-    BlockDriverState *bs;
-
-    for (bs = bdrv_first; bs != NULL; bs = bs->next) {
-        printf("Device %s\n", bs->device_name);
-        if (bs->type == BDRV_TYPE_HD) {
-            printf("device %s format %s\n",
-                   bs->device_name, bs->drv->format_name);
-        }
-    }
-}
-
 void blk_mig_init(void)
 {
-    register_savevm_live("block", 0, 1, block_set_params, block_save_live,
-                         NULL, block_load, &block_mig_state);
+    QSIMPLEQ_INIT(&block_mig_state.bmds_list);
+    QSIMPLEQ_INIT(&block_mig_state.blk_list);
+
+    register_savevm_live(NULL, "block", 0, 1, block_set_params,
+                         block_save_live, NULL, block_load, &block_mig_state);
 }