Commit ebd2f9e7 authored by Kevin Wolf's avatar Kevin Wolf
Browse files

migration/block: Convert saving to BlockBackend 



This creates a new BlockBackend for copying data from an images to the
migration stream on the source host. All I/O for block migration goes
through BlockBackend now.

Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent ad2964b4

migration/block.c

+79 −45
Original line number Diff line number Diff line
@@ -52,7 +52,8 @@ 


typedef struct BlkMigDevState {

    /* Written during setup phase.  Can be read without a lock.  */

    BlockDriverState *bs;

    BlockBackend *blk;

    char *blk_name;

    int shared_base;

    int64_t total_sectors;

    QSIMPLEQ_ENTRY(BlkMigDevState) entry;
@@ -145,9 +146,9 @@ static void blk_send(QEMUFile *f, BlkMigBlock * blk) 
                     | flags);



    /* device name */

    len = strlen(bdrv_get_device_name(blk->bmds->bs));

    len = strlen(blk->bmds->blk_name);

    qemu_put_byte(f, len);

    qemu_put_buffer(f, (uint8_t *)bdrv_get_device_name(blk->bmds->bs), 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.
@@ -201,7 +202,7 @@ static int bmds_aio_inflight(BlkMigDevState *bmds, int64_t sector) 
{

    int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;



    if (sector < bdrv_nb_sectors(bmds->bs)) {

    if (sector < blk_nb_sectors(bmds->blk)) {

        return !!(bmds->aio_bitmap[chunk / (sizeof(unsigned long) * 8)] &

            (1UL << (chunk % (sizeof(unsigned long) * 8))));

    } else {
@@ -235,10 +236,10 @@ static void bmds_set_aio_inflight(BlkMigDevState *bmds, int64_t sector_num, 


static void alloc_aio_bitmap(BlkMigDevState *bmds)

{

    BlockDriverState *bs = bmds->bs;

    BlockBackend *bb = bmds->blk;

    int64_t bitmap_size;



    bitmap_size = bdrv_nb_sectors(bs) + BDRV_SECTORS_PER_DIRTY_CHUNK * 8 - 1;

    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);
@@ -268,19 +269,19 @@ static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds) 
{

    int64_t total_sectors = bmds->total_sectors;

    int64_t cur_sector = bmds->cur_sector;

    BlockDriverState *bs = bmds->bs;

    BlockBackend *bb = bmds->blk;

    BlkMigBlock *blk;

    int nr_sectors;



    if (bmds->shared_base) {

        qemu_mutex_lock_iothread();

        aio_context_acquire(bdrv_get_aio_context(bs));

        aio_context_acquire(blk_get_aio_context(bb));

        while (cur_sector < total_sectors &&

               !bdrv_is_allocated(bs, cur_sector, MAX_IS_ALLOCATED_SEARCH,

                                  &nr_sectors)) {

               !bdrv_is_allocated(blk_bs(bb), cur_sector,

                                  MAX_IS_ALLOCATED_SEARCH, &nr_sectors)) {

            cur_sector += nr_sectors;

        }

        aio_context_release(bdrv_get_aio_context(bs));

        aio_context_release(blk_get_aio_context(bb));

        qemu_mutex_unlock_iothread();

    }
@@ -323,12 +324,12 @@ static int mig_save_device_bulk(QEMUFile *f, BlkMigDevState *bmds) 
     * without the need to acquire the AioContext.

     */

    qemu_mutex_lock_iothread();

    aio_context_acquire(bdrv_get_aio_context(bmds->bs));

    blk->aiocb = bdrv_aio_readv(bs, cur_sector, &blk->qiov,

                                nr_sectors, blk_mig_read_cb, blk);

    aio_context_acquire(blk_get_aio_context(bmds->blk));

    blk->aiocb = blk_aio_preadv(bb, cur_sector * BDRV_SECTOR_SIZE, &blk->qiov,

                                0, blk_mig_read_cb, blk);



    bdrv_reset_dirty_bitmap(bmds->dirty_bitmap, cur_sector, nr_sectors);

    aio_context_release(bdrv_get_aio_context(bmds->bs));

    aio_context_release(blk_get_aio_context(bmds->blk));

    qemu_mutex_unlock_iothread();



    bmds->cur_sector = cur_sector + nr_sectors;
@@ -343,10 +344,10 @@ static int set_dirty_tracking(void) 
    int ret;



    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {

        aio_context_acquire(bdrv_get_aio_context(bmds->bs));

        bmds->dirty_bitmap = bdrv_create_dirty_bitmap(bmds->bs, BLOCK_SIZE,

                                                      NULL, NULL);

        aio_context_release(bdrv_get_aio_context(bmds->bs));

        aio_context_acquire(blk_get_aio_context(bmds->blk));

        bmds->dirty_bitmap = bdrv_create_dirty_bitmap(blk_bs(bmds->blk),

                                                      BLOCK_SIZE, NULL, NULL);

        aio_context_release(blk_get_aio_context(bmds->blk));

        if (!bmds->dirty_bitmap) {

            ret = -errno;

            goto fail;
@@ -357,9 +358,9 @@ static int set_dirty_tracking(void) 
fail:

    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {

        if (bmds->dirty_bitmap) {

            aio_context_acquire(bdrv_get_aio_context(bmds->bs));

            bdrv_release_dirty_bitmap(bmds->bs, bmds->dirty_bitmap);

            aio_context_release(bdrv_get_aio_context(bmds->bs));

            aio_context_acquire(blk_get_aio_context(bmds->blk));

            bdrv_release_dirty_bitmap(blk_bs(bmds->blk), bmds->dirty_bitmap);

            aio_context_release(blk_get_aio_context(bmds->blk));

        }

    }

    return ret;
@@ -372,9 +373,9 @@ static void unset_dirty_tracking(void) 
    BlkMigDevState *bmds;



    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {

        aio_context_acquire(bdrv_get_aio_context(bmds->bs));

        bdrv_release_dirty_bitmap(bmds->bs, bmds->dirty_bitmap);

        aio_context_release(bdrv_get_aio_context(bmds->bs));

        aio_context_acquire(blk_get_aio_context(bmds->blk));

        bdrv_release_dirty_bitmap(blk_bs(bmds->blk), bmds->dirty_bitmap);

        aio_context_release(blk_get_aio_context(bmds->blk));

    }

}
@@ -384,6 +385,11 @@ static void init_blk_migration(QEMUFile *f) 
    BlkMigDevState *bmds;

    int64_t sectors;

    BdrvNextIterator it;

    int i, num_bs = 0;

    struct {

        BlkMigDevState *bmds;

        BlockDriverState *bs;

    } *bmds_bs;



    block_mig_state.submitted = 0;

    block_mig_state.read_done = 0;
@@ -393,27 +399,32 @@ static void init_blk_migration(QEMUFile *f) 
    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) {

            return;

            goto out;

        }



        bmds = g_new0(BlkMigDevState, 1);

        bmds->bs = bs;

        bmds->blk = blk_new();

        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 = block_mig_state.shared_base;

        alloc_aio_bitmap(bmds);

        error_setg(&bmds->blocker, "block device is in use by migration");

        bdrv_op_block_all(bs, bmds->blocker);

        bdrv_ref(bs);



        assert(i < num_bs);

        bmds_bs[i].bmds = bmds;

        bmds_bs[i].bs = bs;



        block_mig_state.total_sector_sum += sectors;
@@ -426,6 +437,24 @@ static void init_blk_migration(QEMUFile *f) 


        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) {

            blk_insert_bs(bmds->blk, bs);



            alloc_aio_bitmap(bmds);

            error_setg(&bmds->blocker, "block device is in use by migration");

            bdrv_op_block_all(bs, bmds->blocker);

        }

    }



out:

    g_free(bmds_bs);

}



/* Called with no lock taken.  */
@@ -482,6 +511,7 @@ 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;
@@ -491,11 +521,11 @@ static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds, 
        blk_mig_lock();

        if (bmds_aio_inflight(bmds, sector)) {

            blk_mig_unlock();

            bdrv_drain(bmds->bs);

            blk_drain(bmds->blk);

        } else {

            blk_mig_unlock();

        }

        if (bdrv_get_dirty(bmds->bs, bmds->dirty_bitmap, sector)) {

        if (bdrv_get_dirty(bs, bmds->dirty_bitmap, sector)) {



            if (total_sectors - sector < BDRV_SECTORS_PER_DIRTY_CHUNK) {

                nr_sectors = total_sectors - sector;
@@ -513,15 +543,18 @@ static int mig_save_device_dirty(QEMUFile *f, BlkMigDevState *bmds, 
                blk->iov.iov_len = nr_sectors * BDRV_SECTOR_SIZE;

                qemu_iovec_init_external(&blk->qiov, &blk->iov, 1);



                blk->aiocb = bdrv_aio_readv(bmds->bs, sector, &blk->qiov,

                                            nr_sectors, blk_mig_read_cb, blk);

                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 = bdrv_read(bmds->bs, sector, blk->buf, nr_sectors);

                ret = blk_pread(bmds->blk, sector * BDRV_SECTOR_SIZE, blk->buf,

                                nr_sectors * BDRV_SECTOR_SIZE);

                if (ret < 0) {

                    goto error;

                }
@@ -559,9 +592,9 @@ static int blk_mig_save_dirty_block(QEMUFile *f, int is_async) 
    int ret = 1;



    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {

        aio_context_acquire(bdrv_get_aio_context(bmds->bs));

        aio_context_acquire(blk_get_aio_context(bmds->blk));

        ret = mig_save_device_dirty(f, bmds, is_async);

        aio_context_release(bdrv_get_aio_context(bmds->bs));

        aio_context_release(blk_get_aio_context(bmds->blk));

        if (ret <= 0) {

            break;

        }
@@ -619,9 +652,9 @@ static int64_t get_remaining_dirty(void) 
    int64_t dirty = 0;



    QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {

        aio_context_acquire(bdrv_get_aio_context(bmds->bs));

        aio_context_acquire(blk_get_aio_context(bmds->blk));

        dirty += bdrv_get_dirty_count(bmds->dirty_bitmap);

        aio_context_release(bdrv_get_aio_context(bmds->bs));

        aio_context_release(blk_get_aio_context(bmds->blk));

    }



    return dirty << BDRV_SECTOR_BITS;
@@ -641,15 +674,16 @@ static void block_migration_cleanup(void *opaque) 


    while ((bmds = QSIMPLEQ_FIRST(&block_mig_state.bmds_list)) != NULL) {

        QSIMPLEQ_REMOVE_HEAD(&block_mig_state.bmds_list, entry);

        bdrv_op_unblock_all(bmds->bs, bmds->blocker);

        bdrv_op_unblock_all(blk_bs(bmds->blk), bmds->blocker);

        error_free(bmds->blocker);



        /* Save ctx, because bmds->bs can disappear during bdrv_unref.  */

        ctx = bdrv_get_aio_context(bmds->bs);

        /* Save ctx, because bmds->blk can disappear during blk_unref.  */

        ctx = blk_get_aio_context(bmds->blk);

        aio_context_acquire(ctx);

        bdrv_unref(bmds->bs);

        blk_unref(bmds->blk);

        aio_context_release(ctx);



        g_free(bmds->blk_name);

        g_free(bmds->aio_bitmap);

        g_free(bmds);

    }