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2017-07-10backup: Switch block_backup.h to byte-basedEric Blake
We are gradually converting to byte-based interfaces, as they are easier to reason about than sector-based. Continue by converting the public interface to backup jobs (no semantic change), including a change to CowRequest to track by bytes instead of cluster indices. Note that this does not change the difference between the public interface (starting point, and size of the subsequent range) and the internal interface (starting and end points). Signed-off-by: Eric Blake <eblake@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com> Reviewed-by: Xie Changlong <xiechanglong@cmss.chinamobile.com> Reviewed-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-09-13Backup: export interfaces for extra serializationChanglong Xie
Normal backup(sync='none') workflow: step 1. NBD peformance I/O write from client to server qcow2_co_writev bdrv_co_writev ... bdrv_aligned_pwritev notifier_with_return_list_notify -> backup_do_cow bdrv_driver_pwritev // write new contents step 2. drive-backup sync=none backup_do_cow { wait_for_overlapping_requests cow_request_begin for(; start < end; start++) { bdrv_co_readv_no_serialising //read old contents from Secondary disk bdrv_co_writev // write old contents to hidden-disk } cow_request_end } step 3. Then roll back to "step 1" to write new contents to Secondary disk. And for replication, we must make sure that we only read the old contents from Secondary disk in order to keep contents consistent. 1) Replication workflow of Secondary virtio-blk ^ -------> 1 NBD | || server 3 replication || ^ ^ || | backing backing | || Secondary disk 6<-------- hidden-disk 5 <-------- active-disk 4 || | ^ || '-------------------------' || drive-backup sync=none 2 Hence, we need these interfaces to implement coarse-grained serialization between COW of Secondary disk and the read operation of replication. Example codes about how to use them: *#include "block/block_backup.h" static coroutine_fn int xxx_co_readv() { CowRequest req; BlockJob *job = secondary_disk->bs->job; if (job) { backup_wait_for_overlapping_requests(job, start, end); backup_cow_request_begin(&req, job, start, end); ret = bdrv_co_readv(); backup_cow_request_end(&req); goto out; } ret = bdrv_co_readv(); out: return ret; } Signed-off-by: Changlong Xie <xiecl.fnst@cn.fujitsu.com> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Signed-off-by: Wang WeiWei <wangww.fnst@cn.fujitsu.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 1469602913-20979-4-git-send-email-xiecl.fnst@cn.fujitsu.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-09-13Backup: clear all bitmap when doing block checkpointWen Congyang
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Signed-off-by: Changlong Xie <xiecl.fnst@cn.fujitsu.com> Signed-off-by: Wang WeiWei <wangww.fnst@cn.fujitsu.com> Signed-off-by: zhanghailiang <zhang.zhanghailiang@huawei.com> Signed-off-by: Gonglei <arei.gonglei@huawei.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 1469602913-20979-3-git-send-email-xiecl.fnst@cn.fujitsu.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>