Sister command to migrate-recover in QMP.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-22-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
The first allow-oob=true command. It's used on destination side when
the postcopy migration is paused and ready for a recovery. After
execution, a new migration channel will be established for postcopy to
continue.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-21-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
s/2.12/2.13/
Though we may not need it, now we init both the src/dst migration
objects in migration_object_init() so that even incoming migration
object would be thread safe (it was not).
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-20-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Finish the last step to do the final handshake for the recovery.
First source sends one MIG_CMD_RESUME to dst, telling that source is
ready to resume.
Then, dest replies with MIG_RP_MSG_RESUME_ACK to source, telling that
dest is ready to resume (after switch to postcopy-active state).
When source received the RESUME_ACK, it switches its state to
postcopy-active, and finally the recovery is completed.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-19-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
After we updated the dirty bitmaps of ramblocks, we also need to update
the critical fields in RAMState to make sure it is ready for a resume.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-18-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This patch implements the first part of core RAM resume logic for
postcopy. ram_resume_prepare() is provided for the work.
When the migration is interrupted by network failure, the dirty bitmap
on the source side will be meaningless, because even the dirty bit is
cleared, it is still possible that the sent page was lost along the way
to destination. Here instead of continue the migration with the old
dirty bitmap on source, we ask the destination side to send back its
received bitmap, then invert it to be our initial dirty bitmap.
The source side send thread will issue the MIG_CMD_RECV_BITMAP requests,
once per ramblock, to ask for the received bitmap. On destination side,
MIG_RP_MSG_RECV_BITMAP will be issued, along with the requested bitmap.
Data will be received on the return-path thread of source, and the main
migration thread will be notified when all the ramblock bitmaps are
synchronized.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-17-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This is hook function to be called when a postcopy migration wants to
resume from a failure. For each module, it should provide its own
recovery logic before we switch to the postcopy-active state.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-16-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Creating new message to reply for MIG_CMD_POSTCOPY_RESUME. One uint32_t
is used as payload to let the source know whether destination is ready
to continue the migration.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-15-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Introducing this new command to be sent when the source VM is ready to
resume the paused migration. What the destination does here is
basically release the fault thread to continue service page faults.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-14-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Introducing new return path message MIG_RP_MSG_RECV_BITMAP to send
received bitmap of ramblock back to source.
This is the reply message of MIG_CMD_RECV_BITMAP, it contains not only
the header (including the ramblock name), and it was appended with the
whole ramblock received bitmap on the destination side.
When the source receives such a reply message (MIG_RP_MSG_RECV_BITMAP),
it parses it, convert it to the dirty bitmap by inverting the bits.
One thing to mention is that, when we send the recv bitmap, we are doing
these things in extra:
- converting the bitmap to little endian, to support when hosts are
using different endianess on src/dst.
- do proper alignment for 8 bytes, to support when hosts are using
different word size (32/64 bits) on src/dst.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-13-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Add a new vm command MIG_CMD_RECV_BITMAP to request received bitmap for
one ramblock.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-12-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
On the destination side, we cannot wake up all the threads when we got
reconnected. The first thing to do is to wake up the main load thread,
so that we can continue to receive valid messages from source again and
reply when needed.
At this point, we switch the destination VM state from postcopy-paused
back to postcopy-recover.
Now we are finally ready to do the resume logic.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-11-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Introducing new migration state "postcopy-recover". If a migration
procedure is paused and the connection is rebuilt afterward
successfully, we'll switch the source VM state from "postcopy-paused" to
the new state "postcopy-recover", then we'll do the resume logic in the
migration thread (along with the return path thread).
This patch only do the state switch on source side. Another following up
patch will handle the state switching on destination side using the same
status bit.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-10-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
s/2.11/2.13/
This patch detects the "resume" flag of migration command, rebuild the
channels only if the flag is set.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-9-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
It will be used when we want to resume one paused migration.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-8-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
s/2.12/2.13/
Allows the fault thread to stop handling page faults temporarily. When
network failure happened (and if we expect a recovery afterwards), we
should not allow the fault thread to continue sending things to source,
instead, it should halt for a while until the connection is rebuilt.
When the dest main thread noticed the failure, it kicks the fault thread
to switch to pause state.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-7-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Let the thread pause for network issues.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-6-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
When there is IO error on the incoming channel (e.g., network down),
instead of bailing out immediately, we allow the dst vm to switch to the
new POSTCOPY_PAUSE state. Currently it is still simple - it waits the
new semaphore, until someone poke it for another attempt.
One note is that here on ram loading thread we cannot detect the
POSTCOPY_ACTIVE state, but we need to detect the more specific
POSTCOPY_INCOMING_RUNNING state, to make sure we have already loaded all
the device states.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-5-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Now when network down for postcopy, the source side will not fail the
migration. Instead we convert the status into this new paused state, and
we will try to wait for a rescue in the future.
If a recovery is detected, migration_thread() will reset its local
variables to prepare for that.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-4-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Introducing a new state "postcopy-paused", which can be used when the
postcopy migration is paused. It is targeted for postcopy network
failure recovery.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-3-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
The old incoming migration is running in main thread and default
gcontext. With the new qio_channel_add_watch_full() we can now let it
run in the thread's own gcontext (if there is one).
Currently this patch does nothing alone. But when any of the incoming
migration is run in another iothread (e.g., the upcoming migrate-recover
command), this patch will bind the incoming logic to the iothread
instead of the main thread (which may already get page faulted and
hanged).
RDMA is not considered for now since it's not even using the QIO watch
framework at all.
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-2-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Once there, we don't need the struct names anywhere, just the
typedefs. And now also document all fields.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
--
Be network agnostic.
Add error checking for all values.
We need to make sure that we have started all the multifd threads.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
In both sides. We still don't transmit anything through them.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Once there, make count field to always be accessed with atomic
operations. To make blocking operations, we need to know that the
thread is running, so create a bool to indicate that.
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
--
Once here, s/terminate_multifd_*-threads/multifd_*_terminate_threads/
This is consistente with every other function
No need to write it to a file. Just need a proper firmware O:-)
Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Fix the bug introduced by da3f56cb2e (migration: remove
ram_save_compressed_page()), It should be 'return' rather than
'res'
Sorry for this stupid mistake :(
Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
Message-Id: <20180428081045.8878-1-xiaoguangrong@tencent.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
- Switch AIO/callback based block drivers to a byte-based interface
- Block jobs: Expose error string via query-block-jobs
- Block job cleanups and fixes
- hmp: Allow using a qdev id in block_set_io_throttle
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Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging
Block layer patches:
- Switch AIO/callback based block drivers to a byte-based interface
- Block jobs: Expose error string via query-block-jobs
- Block job cleanups and fixes
- hmp: Allow using a qdev id in block_set_io_throttle
# gpg: Signature made Tue 15 May 2018 16:33:10 BST
# gpg: using RSA key 7F09B272C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"
# Primary key fingerprint: DC3D EB15 9A9A F95D 3D74 56FE 7F09 B272 C88F 2FD6
* remotes/kevin/tags/for-upstream: (37 commits)
iotests: Add test for -U/force-share conflicts
qemu-img: Use only string options in img_open_opts
qemu-io: Use purely string blockdev options
block: Document BDRV_REQ_WRITE_UNCHANGED support
qemu-img: Check post-truncation size
iotests: Add test for COR across nodes
iotests: Copy 197 for COR filter driver
iotests: Clean up wrap image in 197
block: Support BDRV_REQ_WRITE_UNCHANGED in filters
block/quorum: Support BDRV_REQ_WRITE_UNCHANGED
block: Set BDRV_REQ_WRITE_UNCHANGED for COR writes
block: Add BDRV_REQ_WRITE_UNCHANGED flag
block: BLK_PERM_WRITE includes ..._UNCHANGED
block: Add COR filter driver
iotests: Skip 181 and 201 without userfaultfd
iotests: Add failure matching to common.qemu
docs: Document the new default sizes of the qcow2 caches
qcow2: Give the refcount cache the minimum possible size by default
specs/qcow2: Clarify that compressed clusters have the COPIED bit reset
Fix error message about compressed clusters with OFLAG_COPIED
...
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
- The qcow2 default refcount cache size has been decreased
- Various bug fixes
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Merge remote-tracking branch 'mreitz/tags/pull-block-2018-05-15' into queue-block
- Copy-on-read block driver
- The qcow2 default refcount cache size has been decreased
- Various bug fixes
# gpg: Signature made Tue May 15 16:18:25 2018 CEST
# gpg: using RSA key F407DB0061D5CF40
# gpg: Good signature from "Max Reitz <mreitz@redhat.com>"
# Primary key fingerprint: 91BE B60A 30DB 3E88 57D1 1829 F407 DB00 61D5 CF40
* mreitz/tags/pull-block-2018-05-15: (21 commits)
iotests: Add test for -U/force-share conflicts
qemu-img: Use only string options in img_open_opts
qemu-io: Use purely string blockdev options
block: Document BDRV_REQ_WRITE_UNCHANGED support
qemu-img: Check post-truncation size
iotests: Add test for COR across nodes
iotests: Copy 197 for COR filter driver
iotests: Clean up wrap image in 197
block: Support BDRV_REQ_WRITE_UNCHANGED in filters
block/quorum: Support BDRV_REQ_WRITE_UNCHANGED
block: Set BDRV_REQ_WRITE_UNCHANGED for COR writes
block: Add BDRV_REQ_WRITE_UNCHANGED flag
block: BLK_PERM_WRITE includes ..._UNCHANGED
block: Add COR filter driver
iotests: Skip 181 and 201 without userfaultfd
iotests: Add failure matching to common.qemu
docs: Document the new default sizes of the qcow2 caches
qcow2: Give the refcount cache the minimum possible size by default
specs/qcow2: Clarify that compressed clusters have the COPIED bit reset
Fix error message about compressed clusters with OFLAG_COPIED
...
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180502202051.15493-4-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
img_open_opts() takes a QemuOpts and converts them to a QDict, so all
values therein are strings. Then it may try to call qdict_get_bool(),
however, which will fail with a segmentation fault every time:
$ ./qemu-img info -U --image-opts \
driver=file,filename=/dev/null,force-share=off
[1] 27869 segmentation fault (core dumped) ./qemu-img info -U
--image-opts driver=file,filename=/dev/null,force-share=off
Fix this by using qdict_get_str() and comparing the value as a string.
Also, when adding a force-share value to the QDict, add it as a string
so it fits the rest of the dict.
Cc: qemu-stable@nongnu.org
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180502202051.15493-3-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Currently, qemu-io only uses string-valued blockdev options (as all are
converted directly from QemuOpts) -- with one exception: -U adds the
force-share option as a boolean. This in itself is already a bit
questionable, but a real issue is that it also assumes the value already
existing in the options QDict would be a boolean, which is wrong.
That has the following effect:
$ ./qemu-io -r -U --image-opts \
driver=file,filename=/dev/null,force-share=off
[1] 15200 segmentation fault (core dumped) ./qemu-io -r -U
--image-opts driver=file,filename=/dev/null,force-share=off
Since @opts is converted from QemuOpts, the value must be a string, and
we have to compare it as such. Consequently, it makes sense to also set
it as a string instead of a boolean.
Cc: qemu-stable@nongnu.org
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180502202051.15493-2-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Add BDRV_REQ_WRITE_UNCHANGED to the list of flags honored during pwrite
and pwrite_zeroes, and also add a note on when you absolutely need to
support it.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180502140359.18222-1-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Some block drivers (iscsi and file-posix when dealing with device files)
do not actually support truncation, even though they provide a
.bdrv_truncate() method and will happily return success when providing a
new size that does not exceed the current size. This is because these
drivers expect the user to resize the image outside of qemu and then
provide qemu with that information through the block_resize command
(compare cb1b83e740).
Of course, anyone using qemu-img resize will find that behavior useless.
So we should check the actual size of the image after the supposedly
successful truncation took place, emit an error if nothing changed and
emit a warning if the target size was not met.
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1523065
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180421163957.29872-1-mreitz@redhat.com
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
COR across nodes (that is, you have some filter node between the
actually COR target and the node that performs the COR) cannot reliably
work together with the permission system when there is no explicit COR
node that can request the WRITE_UNCHANGED permission for its child.
This is because COR (currently) sneaks its requests by the usual
permission checks, so it can work without a WRITE* permission; but if
there is a filter node in between, that will re-issue the request, which
then passes through the usual check -- and if nobody has requested a
WRITE_UNCHANGED permission, that check will fail.
There is no real direct fix apart from hoping that there is someone who
has requested that permission; in case of just the qemu-io HMP command
(and no guest device), however, that is not the case. The real real fix
is to implement the copy-on-read flag through an implicitly added COR
node. Such a node can request the necessary permissions as shown in
this test.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180421132929.21610-10-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
iotest 197 tests copy-on-read using the (now old) copy-on-read flag.
Copy it to 215 and modify it to use the COR filter driver instead.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180421132929.21610-9-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20180421132929.21610-8-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Update the rest of the filter drivers to support
BDRV_REQ_WRITE_UNCHANGED. They already forward write request flags to
their children, so we just have to announce support for it.
This patch does not cover the replication driver because that currently
does not support flags at all, and because it just grabs the WRITE
permission for its children when it can, so we should be fine just
submitting the incoming WRITE_UNCHANGED requests as normal writes.
It also does not cover format drivers for similar reasons. They all use
bdrv_format_default_perms() as their .bdrv_child_perm() implementation
so they just always grab the WRITE permission for their file children
whenever possible. In addition, it often would be difficult to
ascertain whether incoming unchanging writes end up as unchanging writes
in their files. So we just leave them as normal potentially changing
writes.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20180421132929.21610-7-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
We just need to forward it to quorum's children (except in case of a
rewrite because of corruption), but for that we first have to support
flags in child requests at all.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20180421132929.21610-6-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20180421132929.21610-5-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This flag signifies that a write request will not change the visible
disk content. With this flag set, it is sufficient to have the
BLK_PERM_WRITE_UNCHANGED permission instead of BLK_PERM_WRITE.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20180421132929.21610-4-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Currently we never actually check whether the WRITE_UNCHANGED
permission has been taken for unchanging writes. But the one check that
is commented out checks both WRITE and WRITE_UNCHANGED; and considering
that WRITE_UNCHANGED is already documented as being weaker than WRITE,
we should probably explicitly document WRITE to include WRITE_UNCHANGED.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20180421132929.21610-3-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This adds a simple copy-on-read filter driver. It relies on the already
existing COR functionality in the central block layer code, which may be
moved here once we no longer need it there.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180421132929.21610-2-mreitz@redhat.com
Reviewed-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
userfaultfd support depends on the host kernel, so it may not be
available. If so, 181 and 201 should be skipped.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180406151731.4285-3-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Peter Xu
Juan Quintela
Xiao Guangrong
Peter Maydell
Kevin Wolf
Max Reitz