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migration/block: Convert saving to BlockBackend

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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: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Kevin Wolf 2016-05-27 19:50:37 +02:00
parent ad2964b4ff
commit ebd2f9e7db
1 changed files with 79 additions and 45 deletions
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124
migration/block.c
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@ -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);
}