From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37589) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b3evx-0002SZ-1v for qemu-devel@nongnu.org; Fri, 20 May 2016 03:33:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b3evu-0000rT-P3 for qemu-devel@nongnu.org; Fri, 20 May 2016 03:33:19 -0400 From: Changlong Xie Date: Fri, 20 May 2016 15:36:13 +0800 Message-ID: <1463729780-31982-4-git-send-email-xiecl.fnst@cn.fujitsu.com> In-Reply-To: <1463729780-31982-1-git-send-email-xiecl.fnst@cn.fujitsu.com> References: <1463729780-31982-1-git-send-email-xiecl.fnst@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain Subject: [Qemu-devel] [PATCH v19 03/10] Backup: export interfaces for extra serialization List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu devel , Stefan Hajnoczi , Fam Zheng , Max Reitz , Kevin Wolf , Jeff Cody Cc: qemu block , Paolo Bonzini , John Snow , Eric Blake , Markus Armbruster , "Dr. David Alan Gilbert" , Dong Eddie , Jiang Yunhong , zhanghailiang , Gonglei , Wen Congyang , Changlong 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 Signed-off-by: Wen Congyang --- block/backup.c | 41 ++++++++++++++++++++++++++++++++++------- include/block/block_backup.h | 14 ++++++++++++++ 2 files changed, 48 insertions(+), 7 deletions(-) diff --git a/block/backup.c b/block/backup.c index 93bfd4c..57bcfa3 100644 --- a/block/backup.c +++ b/block/backup.c @@ -28,13 +28,6 @@ #define BACKUP_CLUSTER_SIZE_DEFAULT (1 << 16) #define SLICE_TIME 100000000ULL /* ns */ -typedef struct CowRequest { - int64_t start; - int64_t end; - QLIST_ENTRY(CowRequest) list; - CoQueue wait_queue; /* coroutines blocked on this request */ -} CowRequest; - typedef struct BackupBlockJob { BlockJob common; BlockDriverState *target; @@ -268,6 +261,40 @@ void backup_do_checkpoint(BlockJob *job, Error **errp) bitmap_zero(backup_job->done_bitmap, len); } +void backup_wait_for_overlapping_requests(BlockJob *job, int64_t sector_num, + int nb_sectors) +{ + BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common); + int64_t sectors_per_cluster = cluster_size_sectors(backup_job); + int64_t start, end; + + assert(job->driver->job_type == BLOCK_JOB_TYPE_BACKUP); + + start = sector_num / sectors_per_cluster; + end = DIV_ROUND_UP(sector_num + nb_sectors, sectors_per_cluster); + wait_for_overlapping_requests(backup_job, start, end); +} + +void backup_cow_request_begin(CowRequest *req, BlockJob *job, + int64_t sector_num, + int nb_sectors) +{ + BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common); + int64_t sectors_per_cluster = cluster_size_sectors(backup_job); + int64_t start, end; + + assert(job->driver->job_type == BLOCK_JOB_TYPE_BACKUP); + + start = sector_num / sectors_per_cluster; + end = DIV_ROUND_UP(sector_num + nb_sectors, sectors_per_cluster); + cow_request_begin(req, backup_job, start, end); +} + +void backup_cow_request_end(CowRequest *req) +{ + cow_request_end(req); +} + static const BlockJobDriver backup_job_driver = { .instance_size = sizeof(BackupBlockJob), .job_type = BLOCK_JOB_TYPE_BACKUP, diff --git a/include/block/block_backup.h b/include/block/block_backup.h index 3753bcb..e0e7ce6 100644 --- a/include/block/block_backup.h +++ b/include/block/block_backup.h @@ -1,3 +1,17 @@ #include "block/block_int.h" +typedef struct CowRequest { + int64_t start; + int64_t end; + QLIST_ENTRY(CowRequest) list; + CoQueue wait_queue; /* coroutines blocked on this request */ +} CowRequest; + +void backup_wait_for_overlapping_requests(BlockJob *job, int64_t sector_num, + int nb_sectors); +void backup_cow_request_begin(CowRequest *req, BlockJob *job, + int64_t sector_num, + int nb_sectors); +void backup_cow_request_end(CowRequest *req); + void backup_do_checkpoint(BlockJob *job, Error **errp); -- 1.9.3