backup_start() creates a block job that copies a point-in-time snapshot
of a block device to a target block device.
We call backup_do_cow() for each write during backup. That function
reads the original data from the block device before it gets
overwritten. The data is then written to the target device.
Currently backup cluster size is hardcoded to 65536 bytes.
[I made a number of changes to Dietmar's original patch and folded them
in to make code review easy. Here is the full list:
* Drop BackupDumpFunc interface in favor of a target block device
* Detect zero clusters with buffer_is_zero() and use bdrv_co_write_zeroes()
* Use 0 delay instead of 1us, like other block jobs
* Unify creation/start functions into backup_start()
* Simplify cleanup, free bitmap in backup_run() instead of cb
* function
* Use HBitmap to avoid duplicating bitmap code
* Use bdrv_getlength() instead of accessing ->total_sectors
* directly
* Delete the backup.h header file, it is no longer necessary
* Move ./backup.c to block/backup.c
* Remove #ifdefed out code
* Coding style and whitespace cleanups
* Use bdrv_add_before_write_notifier() instead of blockjob-specific hooks
* Keep our own in-flight CowRequest list instead of using block.c
tracked requests. This means a little code duplication but is much
simpler than trying to share the tracked requests list and use the
backup block size.
* Add on_source_error and on_target_error error handling.
* Use trace events instead of DPRINTF()
-- stefanha]
Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch is a pure code move patch, except following modification:
1 get_human_readable_size() is changed to static function.
2 dump_human_image_info() is renamed to bdrv_image_info_dump().
3 in qmp_query_block() and qmp_query_blockstats, use bdrv_next(bs)
instead of direct traverse of global array 'bdrv_states'.
4 collect_snapshots() and collect_image_info() are renamed, unused parameter
*fmt in collect_image_info() is removed.
5 code style fix.
To avoid conflict and tip better, macro in header file is BLOCK_QAPI_H
instead of QAPI_H. Now block.h and snapshot.h are at the same level in
include path, block_int.h and qapi.h will both include them.
Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
All snapshot related code, except bdrv_snapshot_dump() and
bdrv_is_snapshot(), is moved to block/snapshot.c. bdrv_snapshot_dump()
will be moved to another file later. bdrv_is_snapshot() is not related
with internal snapshot. It also fixes small code style errors reported
by check script.
Signed-off-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This is the initial block driver framework for VHDX image support
(i.e. Hyper-V image file formats), that supports opening VHDX files, and
parsing the headers.
This commit does not yet enable:
- reading
- writing
- updating the header
- differencing files (images with parents)
- log replay / dirty logs (only clean images)
This is based on Microsoft's VHDX specification:
"VHDX Format Specification v0.95", published 4/12/2012
https://www.microsoft.com/en-us/download/details.aspx?id=29681
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
qemu-system-x86_64 -drive file=ssh://hostname/some/image
QEMU will ssh into 'hostname' and open '/some/image' which is made
available as a standard block device.
You can specify a username (ssh://user@host/...) and/or a port number
(ssh://host:port/...). You can also use an alternate syntax using
properties (file.user, file.host, file.port, file.path).
Current limitations:
- Authentication must be done without passwords or passphrases, using
ssh-agent. Other authentication methods are not supported.
- Uses a single connection, instead of concurrent AIO with multiple
SSH connections.
This is implemented using libssh2 on the client side. The server just
requires a regular ssh daemon with sftp-server support. Most ssh
daemons on Unix/Linux systems will work out of the box.
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Cc: Stefan Hajnoczi <stefanha@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
With the new support for EventNotifiers in the AIO event loop, we
can hook a completion port to every opened file and use asynchronous
I/O on them.
Wine's support is extremely inefficient, also because it really does
the I/O synchronously on regular files. (!) But it works, and it is
good to keep the Win32 and POSIX ports as similar as possible.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The Win32 implementation will only accept EventNotifiers, thus a few
drivers are disabled under Windows. EventNotifiers are a good match
for the GSource implementation, too, because the Win32 port of glib
allows to place their HANDLEs in a GPollFD.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This patch adds the implementation of a new job that mirrors a disk to
a new image while letting the guest continue using the old image.
The target is treated as a "black box" and data is copied from the
source to the target in the background. This can be used for several
purposes, including storage migration, continuous replication, and
observation of the guest I/O in an external program. It is also a
first step in replacing the inefficient block migration code that is
part of QEMU.
The job is possibly never-ending, but it is logically structured into
two phases: 1) copy all data as fast as possible until the target
first gets in sync with the source; 2) keep target in sync and
ensure that reopening to the target gets a correct (full) copy
of the source data.
The second phase is indicated by the progress in "info block-jobs"
reporting the current offset to be equal to the length of the file.
When the job is cancelled in the second phase, QEMU will run the
job until the source is clean and quiescent, then it will report
successful completion of the job.
In other words, the BLOCK_JOB_CANCELLED event means that the target
may _not_ be consistent with a past state of the source; the
BLOCK_JOB_COMPLETED event means that the target is consistent with
a past state of the source. (Note that it could already happen
that management lost the race against QEMU and got a completion
event instead of cancellation).
It is not yet possible to complete the job and switch over to the target
disk. The next patches will fix this and add many refinements to the
basic idea introduced here. These include improved error management,
some tunable knobs and performance optimizations.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This adds the live commit coroutine. This iteration focuses on the
commit only below the active layer, and not the active layer itself.
The behaviour is similar to block streaming; the sectors are walked
through, and anything that exists above 'base' is committed back down
into base. At the end, intermediate images are deleted, and the
chain stitched together. Images are restored to their original open
flags upon completion.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch adds gluster as the new block backend in QEMU. This gives
QEMU the ability to boot VM images from gluster volumes. Its already
possible to boot from VM images on gluster volumes using FUSE mount, but
this patchset provides the ability to boot VM images from gluster volumes
by by-passing the FUSE layer in gluster. This is made possible by
using libgfapi routines to perform IO on gluster volumes directly.
VM Image on gluster volume is specified like this:
file=gluster[+transport]://[server[:port]]/volname/image[?socket=...]
'gluster' is the protocol.
'transport' specifies the transport type used to connect to gluster
management daemon (glusterd). Valid transport types are
tcp, unix and rdma. If a transport type isn't specified, then tcp
type is assumed.
'server' specifies the server where the volume file specification for
the given volume resides. This can be either hostname, ipv4 address
or ipv6 address. ipv6 address needs to be within square brackets [ ].
If transport type is 'unix', then 'server' field should not be specifed.
The 'socket' field needs to be populated with the path to unix domain
socket.
'port' is the port number on which glusterd is listening. This is optional
and if not specified, QEMU will send 0 which will make gluster to use the
default port. If the transport type is unix, then 'port' should not be
specified.
'volname' is the name of the gluster volume which contains the VM image.
'image' is the path to the actual VM image that resides on gluster volume.
Examples:
file=gluster://1.2.3.4/testvol/a.img
file=gluster+tcp://1.2.3.4/testvol/a.img
file=gluster+tcp://1.2.3.4:24007/testvol/dir/a.img
file=gluster+tcp://[1:2:3:4:5:6:7:8]/testvol/dir/a.img
file=gluster+tcp://[1:2:3:4:5:6:7:8]:24007/testvol/dir/a.img
file=gluster+tcp://server.domain.com:24007/testvol/dir/a.img
file=gluster+unix:///testvol/dir/a.img?socket=/tmp/glusterd.socket
file=gluster+rdma://1.2.3.4:24007/testvol/a.img
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Dietmar Maurer
Wenchao Xia
Jeff Cody
Richard W.M. Jones
Paolo Bonzini
Bharata B Rao