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2014-02-28qmp: Make Quorum error events more palatable.Benoît Canet
Insert quorum QMP events documentation alphabetically. Also change the "ret" errno value by an optional "error" being an strerror(-ret) in the QUORUM_REPORT_BAD qmp event. Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-02-21quorum: Simplify quorum_open()Max Reitz
Although it may not look like it, this patch simplifies quorum_open(). qdict_array_split() is now able to return QLists with different objects than only QDicts, therefore it will now do all the work and quorum_open() does not have to handle reference strings by itself. This allows mixing full option dicts and reference strings for specifying the child block devices of quorum; furthermore, it improves handling of malformed specifications. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21quorum: Add quorum_open() and quorum_close().Benoît Canet
Example of command line: -drive if=virtio,driver=quorum,\ children.0.file.filename=1.raw,\ children.0.node-name=1.raw,\ children.0.driver=raw,\ children.1.file.filename=2.raw,\ children.1.node-name=2.raw,\ children.1.driver=raw,\ children.2.file.filename=3.raw,\ children.2.node-name=3.raw,\ children.2.driver=raw,\ vote-threshold=2 blkverify=on with vote-threshold=2 and two files can be passed to emulate blkverify. Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21quorum: Implement recursive .bdrv_recurse_is_first_non_filter in quorum.Benoît Canet
This is used to activate quorum snapshot. Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21quorum: Add quorum_co_flush().Benoît Canet
Makes a vote to select error if any. Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21quorum: Add quorum_invalidate_cache().Benoît Canet
We really want that live migration works with quorum so implement quorum_invalidate_cache(). Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21quorum: Add quorum_getlength().Benoît Canet
Check that every bs file returns the same length. Otherwise, return -EIO to disable the quorum and avoid length discrepancy. Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21quorum: Add quorum mechanism.Benoît Canet
This patchset enables the core of the quorum mechanism. The num_children reads are compared to get the majority version and if this version exists more than threshold times the guest won't see the error at all. If a block is corrupted or if an error occurs during an IO or if the quorum cannot be established QMP events are used to report to the management. Use gnutls's SHA-256 to compare versions. --enable-quorum must be used to enable the feature. Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21quorum: Add quorum_aio_readv.Benoît Canet
Add code to do num_children reads in parallel and cleanup the structures afterwards. Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21quorum: Add quorum_aio_writev and its dependencies.Benoît Canet
Writes are mirrored num_children times on num_children devices. Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21quorum: Create BDRVQuorumState and BlkDriver and do init.Benoît Canet
Create the structure holding the quorum settings and write the minimal block driver instanciation boilerplate. Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-21quorum: Create quorum.c, add QuorumChildRequest and QuorumAIOCB.Benoît Canet
Quorum is a block filter mirroring writes to num_children children. For reads quorum reads each children and does a vote. If more than vote_threshold versions are identical the quorum is reached and this winning version is returned to the guest. So quorum prevents bit corruption. For high availability purpose minority errors are reported via QMP but the guest does not see them. This patch creates the driver C source file and introduces the structures that will be used in asynchronous reads and writes. Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>