Am 24.06.2013 um 17:13 hat Stefan Hajnoczi geschrieben: > Note: These patches apply to kevin/block. You can also grab the code from git > here: > git://github.com/stefanha/qemu.git block-backup-core > > This series adds a new QMP command, drive-backup, which takes a point-in-time > snapshot of a block device. The snapshot is copied out to a target block > device. A simple example is: > > drive-backup device=virtio0 format=qcow2 target=backup-20130401.qcow2 > > The original drive-backup blockjob was written by Dietmar Maurer > <diet...@proxmox.com>. He is currently busy but I feel the feature is worth > pushing into QEMU since there has been interest. This is my version of his > patch, plus the QMP command and qemu-iotests test case. > > QMP 'transaction' support is included since v3. It adds support for atomic > snapshots of multiple block devices. I also added an 'abort' transaction to > allow testing of the .abort()/.cleanup() code path. Thanks to Wenchao for > making qmp_transaction() extensible. > > How is this different from block-stream and drive-mirror? > --------------------------------------------------------- > Both block-stream and drive-mirror do not provide immediate point-in-time > snapshots. Instead they copy data into a new file and then switch to it. In > other words, the point at which the "snapshot" is taken cannot be controlled > directly. > > drive-backup intercepts guest writes and saves data into the target block > device before it is overwritten. The target block device can be a raw image > file, backing files are not used to implement this feature. > > How can drive-backup be used? > ----------------------------- > The simplest use-case is to copy a point-in-time snapshot to a local file. > > More advanced users may wish to make the target an NBD URL. The NBD server > listening on the other side can process the backup writes any way it wishes. > I > previously posted an RFC series with a backup server that streamed Dietmar's > VMA backup archive format. > > What's next for drive-backup? > ----------------------------- > 1. Sync modes like drive-mirror (top, full, none). This makes it possible to > preserve the backing file chain. > > v6: > * Note: I will send HMP support as a follow-up patch > * Note: The 'Abort' action's name is unchanged > * Extract wait_until_completed() into iotests.py > * Populate image with non-zero data and resume job in 055 test_pause() > [kwolf] > * Document NotifierWithReturn return value semantics [eblake] > * Convert DPRINTF() to trace events [pbonzini] > * Avoid calling bdrv_getlength() inside the loop [kwolf] > * Comment that BlockJob->offset is an opaque progress value [kwolf] > * Align '=' to same column [kwolf] > * Use bdrv_set_enable_write_cache(target, true) [kwolf] > * Use BACKUP_SECTORS_PER_CLUSTERS instead of 1 sector for clarity [kwolf] > * Check cancel_and_wait() 'data/type' is 'backup' in 055 [kwolf] > > v5: > * Use bdrv_co_write_zeroes(job->target) [kwolf] > > This change means that we write zeroes over NBD again. The optimization > can > be reintroduced by skipping zeroes when bdrv_has_zero_init() is true and > the > sectors are allocated. Leave that for a future series, if we decide to do > this optimization again because it may require extra block driver > configuration to indicate that an image has zero init. > > * iostatus error handling [kwolf/pbonzini] > > Add configurable on-source-error and on-target-error actions just like > drive-mirror. These are used when the block job coroutine hits an error. > If we are in guest write request context, return the errno and let the > usual > guest error handling take over. > > * Allow BdrvActionOps->commit() to be NULL [eblake] > * Use bdrv_getlength() in qmp_drive_mirror() [kwolf] > * Drop redundant proto_drv check [kwolf] > * Fix outdated DPRINTF() function names > * Drop comment about non-existent bitmap coroutine race [kwolf] > * Rename BACKUP_SECTORS_PER_CLUSTER [kwolf] > * Fix completion when image is not multiple of backup cluster size [fam] > > v4: > * Use notifier lists and BdrvTrackedRequest instead of custom callbacks > [bonzini] > * Add drive-backup QMP example JSON [eblake] > * Add "Since: 1.6" to QMP schema changes [eblake] > > v3: > * Rename to drive-backup for consistency with drive-mirror [kwolf] > * Add QMP transaction support [kwolf] > * Introduce bdrv_add_before_write_cb() to hook writes > * Mention 'query-block-jobs' lists job of type 'backup' [eblake] > * Rename rwlock to flush_rwlock [kwolf] > * Fix space in block/backup.c comment [kwolf] > > v2: > * s/block_backup/block-backup/ in commit message [eblake] > * Avoid funny spacing in QMP docs [eblake] > * Document query-block-jobs and block-job-cancel usage [eblake] > > Dietmar Maurer (1): > block: add basic backup support to block driver > > Stefan Hajnoczi (11): > notify: add NotiferWithReturn so notifier list can abort > block: add bdrv_add_before_write_notifier() > blockdev: drop redundant proto_drv check > blockdev: use bdrv_getlength() in qmp_drive_mirror() > block: add drive-backup QMP command > blockdev: rename BlkTransactionStates to singular > blockdev: allow BdrvActionOps->commit() to be NULL > blockdev: add DriveBackup transaction > blockdev: add Abort transaction > qemu-iotests: extract wait_until_completed() into iotests.py > qemu-iotests: add 055 drive-backup test case > > block.c | 23 +-- > block/Makefile.objs | 1 + > block/backup.c | 341 > ++++++++++++++++++++++++++++++++++++++++++ > blockdev.c | 288 ++++++++++++++++++++++++++--------- > include/block/block_int.h | 42 +++++- > include/qemu/notify.h | 29 ++++ > qapi-schema.json | 97 +++++++++++- > qmp-commands.hx | 46 ++++++ > tests/qemu-iotests/041 | 14 +- > tests/qemu-iotests/055 | 282 ++++++++++++++++++++++++++++++++++ > tests/qemu-iotests/055.out | 5 + > tests/qemu-iotests/group | 1 + > tests/qemu-iotests/iotests.py | 15 ++ > trace-events | 8 + > util/notify.c | 30 ++++ > 15 files changed, 1129 insertions(+), 93 deletions(-) > create mode 100644 block/backup.c > create mode 100755 tests/qemu-iotests/055 > create mode 100644 tests/qemu-iotests/055.out
Thanks, applied all to the block branch. The only comment I had is the missing 'const' in patch 3, which I added myself while applying the patch. I also sent a patch to make the same change in the existing block jobs. Kevin
