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Re: [Qemu-devel] [PATCH v6 00/12] block: drive-backup live backup comman
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH v6 00/12] block: drive-backup live backup command |
Date: |
Tue, 25 Jun 2013 15:16:28 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
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
> <address@hidden>. 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
- [Qemu-devel] [PATCH v6 03/12] block: add basic backup support to block driver, (continued)
- [Qemu-devel] [PATCH v6 03/12] block: add basic backup support to block driver, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 10/12] blockdev: add Abort transaction, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 11/12] qemu-iotests: extract wait_until_completed() into iotests.py, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 05/12] blockdev: use bdrv_getlength() in qmp_drive_mirror(), Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 02/12] block: add bdrv_add_before_write_notifier(), Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 04/12] blockdev: drop redundant proto_drv check, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 06/12] block: add drive-backup QMP command, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 07/12] blockdev: rename BlkTransactionStates to singular, Stefan Hajnoczi, 2013/06/24
- [Qemu-devel] [PATCH v6 12/12] qemu-iotests: add 055 drive-backup test case, Stefan Hajnoczi, 2013/06/24
- Re: [Qemu-devel] [PATCH v6 00/12] block: drive-backup live backup command,
Kevin Wolf <=