From ebd2f9e7db4b6cbc2f144b9cef397503b3e956b5 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Fri, 27 May 2016 19:50:37 +0200 Subject: [PATCH] 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: Kevin Wolf Reviewed-by: Stefan Hajnoczi --- migration/block.c | 124 +++++++++++++++++++++++++++++----------------- 1 file changed, 79 insertions(+), 45 deletions(-) diff --git a/migration/block.c b/migration/block.c index 30af182f24..ebc10e628d 100644 --- a/migration/block.c +++ b/migration/block.c @@ -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); }