In many cases, the required permissions of one node on its children
depend on what its parents require from it. For example, the raw format
or most filter drivers only need to request consistent reads if that's
something that one of their parents wants.
In order to achieve this, this patch introduces two new BlockDriver
callbacks. The first one lets drivers first check (recursively) whether
the requested permissions can be set; the second one actually sets the
new permission bitmask.
Also add helper functions that drivers can use in their implementation
of the callbacks to update their permissions on a specific child.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
When attaching a node as a child to a new parent, the required and
shared permissions for this parent are checked against all other parents
of the node now, and an error is returned if there is a conflict.
This allows error returns to a function that previously always
succeeded, and the same is true for quite a few callers and their
callers. Converting all of them within the same patch would be too much,
so for now everyone tells that they don't need any permissions and allow
everyone else to do anything. This way we can use &error_abort initially
and convert caller by caller to pass actual permission requirements and
implement error handling.
All these places are marked with FIXME comments and it will be the job
of the next patches to clean them up again.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
It will have to return an error soon, so prepare the callers for it.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
This patch defines the permission categories that will be used by the
new op blocker system.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
This function allows to create more or less normal BlockDriverStates
even for BlockDrivers that aren't globally registered (e.g. helper
filters for block jobs).
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-19-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This patch prepares for the removal of unnecessary lockcnt inc/dec pairs.
Extract the dispatching loop for file descriptor handlers into a new
function aio_dispatch_handlers, and then inline aio_dispatch into
aio_poll.
aio_dispatch can now become void.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-17-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
aio_co_wake provides the infrastructure to start a coroutine on a "home"
AioContext. It will be used by CoMutex and CoQueue, so that coroutines
don't jump from one context to another when they go to sleep on a
mutex or waitqueue. However, it can also be used as a more efficient
alternative to one-shot bottom halves, and saves the effort of tracking
which AioContext a coroutine is running on.
aio_co_schedule is the part of aio_co_wake that starts a coroutine
on a remove AioContext, but it is also useful to implement e.g.
bdrv_set_aio_context callbacks.
The implementation of aio_co_schedule is based on a lock-free
multiple-producer, single-consumer queue. The multiple producers use
cmpxchg to add to a LIFO stack. The consumer (a per-AioContext bottom
half) grabs all items added so far, inverts the list to make it FIFO,
and goes through it one item at a time until it's empty. The data
structure was inspired by OSv, which uses it in the very code we'll
"port" to QEMU for the thread-safe CoMutex.
Most of the new code is really tests.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20170213135235.12274-3-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Commit 6f6071745b ("raw-posix: Fetch max sectors for host block device")
introduced a routine to call the kernel BLKSECTGET ioctl, which stores the
result back to user space. However, the size of the data returned depends
on the routine handling the ioctl. The (compat_)blkdev_ioctl returns a
short, while sg_ioctl returns an int. Thus, on big-endian systems, we can
find ourselves accidentally shifting the result to a much larger value.
(On s390x, a short is 16 bits while an int is 32 bits.)
Also, the two ioctl handlers return values in different scales (block
returns sectors, while sg returns bytes), so some tweaking of the outputs
is required such that hdev_get_max_transfer_length returns a value in a
consistent set of units.
Signed-off-by: Eric Farman <farman@linux.vnet.ibm.com>
Message-Id: <20170120162527.66075-3-farman@linux.vnet.ibm.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This will make it possible to walk the list of bottom halves without
holding the AioContext lock---and in turn to call bottom half
handlers without holding the lock.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20170112180800.21085-4-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This will be used for AioHandlers too. There is going to be little
or no contention, so it is better to reuse the same lock.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20170112180800.21085-2-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
bdrv_io_plug and bdrv_io_unplug are only called (via their
BlockBackend equivalents) after starting asynchronous I/O.
bdrv_drain is not going to be called while they are running,
because---even if a coroutine runs for some reason---it will
only drain in the next iteration of the event loop through
bdrv_co_yield_to_drain.
So this mechanism is unnecessary, get rid of it.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161129113334.605-1-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
These files deal with the file protocol, not the raw format (the
file protocol is often used with other formats, and the raw
format is not forced to use the file protocol). Rename things
to make it a bit easier to follow.
Suggested-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch is based on the algorithm for the kvm.ko halt_poll_ns
parameter in Linux. The initial polling time is zero.
If the event loop is woken up within the maximum polling time it means
polling could be effective, so grow polling time.
If the event loop is woken up beyond the maximum polling time it means
polling is not effective, so shrink polling time.
If the event loop makes progress within the current polling time then
the sweet spot has been reached.
This algorithm adjusts the polling time so it can adapt to variations in
workloads. The goal is to reach the sweet spot while also recognizing
when polling would hurt more than help.
Two new trace events, poll_grow and poll_shrink, are added for observing
polling time adjustment.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161201192652.9509-13-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The begin and end callbacks can be used to prepare for the polling loop
and clean up when polling stops. Note that they may only be called once
for multiple aio_poll() calls if polling continues to succeed. Once
polling fails the end callback is invoked before aio_poll() resumes file
descriptor monitoring.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161201192652.9509-11-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The AioContext event loop uses ppoll(2) or epoll_wait(2) to monitor file
descriptors or until a timer expires. In cases like virtqueues, Linux
AIO, and ThreadPool it is technically possible to wait for events via
polling (i.e. continuously checking for events without blocking).
Polling can be faster than blocking syscalls because file descriptors,
the process scheduler, and system calls are bypassed.
The main disadvantage to polling is that it increases CPU utilization.
In classic polling configuration a full host CPU thread might run at
100% to respond to events as quickly as possible. This patch implements
a timeout so we fall back to blocking syscalls if polling detects no
activity. After the timeout no CPU cycles are wasted on polling until
the next event loop iteration.
The run_poll_handlers_begin() and run_poll_handlers_end() trace events
are added to aid performance analysis and troubleshooting. If you need
to know whether polling mode is being used, trace these events to find
out.
Note that the AioContext is now re-acquired before disabling notify_me
in the non-polling case. This makes the code cleaner since notify_me
was enabled outside the non-polling AioContext release region. This
change is correct since it's safe to keep notify_me enabled longer
(disabling is an optimization) but potentially causes unnecessary
event_notifer_set() calls. I think the chance of performance regression
is small here.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161201192652.9509-4-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The new AioPollFn io_poll() argument to aio_set_fd_handler() and
aio_set_event_handler() is used in the next patch.
Keep this code change separate due to the number of files it touches.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161201192652.9509-3-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Polling mode will not call ppoll(2)/epoll_wait(2). Therefore we know
there are no fds ready and should avoid looping over fd handlers in
aio_dispatch().
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161201192652.9509-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Commit 87f68d3182 (block: drop aio
functions that operate on the main AioContext) drops qemu_aio_wait
function references mostly while leaves these behind, clean up them.
Signed-off-by: Yaowei Bai <baiyaowei@cmss.chinamobile.com>
Message-Id: <1480566640-27264-3-git-send-email-baiyaowei@cmss.chinamobile.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Refactor backup_start as backup_job_create, which only creates the job,
but does not automatically start it. The old interface, 'backup_start',
is not kept in favor of limiting the number of nearly-identical interfaces
that would have to be edited to keep up with QAPI changes in the future.
Callers that wish to synchronously start the backup_block_job can
instead just call block_job_start immediately after calling
backup_job_create.
Transactions are updated to use the new interface, calling block_job_start
only during the .commit phase, which helps prevent race conditions where
jobs may finish before we even finish building the transaction. This may
happen, for instance, during empty block backup jobs.
Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 1478587839-9834-6-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
Instead of automatically starting jobs at creation time via backup_start
et al, we'd like to return a job object pointer that can be started
manually at later point in time.
For now, add the block_job_start mechanism and start the jobs
automatically as we have been doing, with conversions job-by-job coming
in later patches.
Of note: cancellation of unstarted jobs will perform all the normal
cleanup as if the job had started, particularly abort and clean. The
only difference is that we will not emit any events, because the job
never actually started.
Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 1478587839-9834-5-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
Add an explicit start field to specify the entrypoint. We already have
ownership of the coroutine itself AND managing the lifetime of the
coroutine, let's take control of creation of the coroutine, too.
This will allow us to delay creation of the actual coroutine until we
know we'll actually start a BlockJob in block_job_start. This avoids
the sticky question of how to "un-create" a Coroutine that hasn't been
started yet.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 1478587839-9834-4-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
Cleaning up after we have deferred to the main thread but before the
transaction has converged can be dangerous and result in deadlocks
if the job cleanup invokes any BH polling loops.
A job may attempt to begin cleaning up, but may induce another job to
enter its cleanup routine. The second job, part of our same transaction,
will block waiting for the first job to finish, so neither job may now
make progress.
To rectify this, allow jobs to register a cleanup operation that will
always run regardless of if the job was in a transaction or not, and
if the transaction job group completed successfully or not.
Move sensitive cleanup to this callback instead which is guaranteed to
be run only after the transaction has converged, which removes sensitive
timing constraints from said cleanup.
Furthermore, in future patches these cleanup operations will be performed
regardless of whether or not we actually started the job. Therefore,
cleanup callbacks should essentially confine themselves to undoing create
operations, e.g. setup actions taken in what is now backup_start.
Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 1478587839-9834-3-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
* NBD write zeroes support (Eric)
* Memory backend fixes (Haozhong)
* Atomics fix (Alex)
* New AVX512 features (Luwei)
* "make check" logging fix (Paolo)
* Chardev refactoring fallout (Paolo)
* Small checkpatch improvements (Paolo, Jeff)
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Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging
* NBD bugfix (Changlong)
* NBD write zeroes support (Eric)
* Memory backend fixes (Haozhong)
* Atomics fix (Alex)
* New AVX512 features (Luwei)
* "make check" logging fix (Paolo)
* Chardev refactoring fallout (Paolo)
* Small checkpatch improvements (Paolo, Jeff)
# gpg: Signature made Wed 02 Nov 2016 08:31:11 AM GMT
# gpg: using RSA key 0xBFFBD25F78C7AE83
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>"
# gpg: aka "Paolo Bonzini <pbonzini@redhat.com>"
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4 E2F7 7E15 100C CD36 69B1
# Subkey fingerprint: F133 3857 4B66 2389 866C 7682 BFFB D25F 78C7 AE83
* remotes/bonzini/tags/for-upstream: (30 commits)
main-loop: Suppress I/O thread warning under qtest
docs/rcu.txt: Fix minor typo
vl: exit qemu on guest panic if -no-shutdown is not set
checkpatch: allow spaces before parenthesis for 'coroutine_fn'
x86: add AVX512_4VNNIW and AVX512_4FMAPS features
slirp: fix CharDriver breakage
qemu-char: do not forward events through the mux until QEMU has started
nbd: Implement NBD_CMD_WRITE_ZEROES on client
nbd: Implement NBD_CMD_WRITE_ZEROES on server
nbd: Improve server handling of shutdown requests
nbd: Refactor conversion to errno to silence checkpatch
nbd: Support shorter handshake
nbd: Less allocation during NBD_OPT_LIST
nbd: Let client skip portions of server reply
nbd: Let server know when client gives up negotiation
nbd: Share common option-sending code in client
nbd: Send message along with server NBD_REP_ERR errors
nbd: Share common reply-sending code in server
nbd: Rename struct nbd_request and nbd_reply
nbd: Rename NbdClientSession to NBDClientSession
...
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Upstream NBD protocol recently added the ability to efficiently
write zeroes without having to send the zeroes over the wire,
along with a flag to control whether the client wants to allow
a hole.
Note that when it comes to requiring full allocation, vs.
permitting optimizations, the NBD spec intentionally picked a
different sense for the flag; the rules in qemu are:
MAY_UNMAP == 0: must write zeroes
MAY_UNMAP == 1: may use holes if reads will see zeroes
while in NBD, the rules are:
FLAG_NO_HOLE == 1: must write zeroes
FLAG_NO_HOLE == 0: may use holes if reads will see zeroes
In all cases, the 'may use holes' scenario is optional (the
server need not use a hole, and must not use a hole if
subsequent reads would not see zeroes).
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-16-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
NBD commit 6d34500b clarified how clients and servers are supposed
to behave before closing a connection. It added NBD_REP_ERR_SHUTDOWN
(for the server to announce it is about to go away during option
haggling, so the client should quit sending NBD_OPT_* other than
NBD_OPT_ABORT) and ESHUTDOWN (for the server to announce it is about
to go away during transmission, so the client should quit sending
NBD_CMD_* other than NBD_CMD_DISC). It also clarified that
NBD_OPT_ABORT gets a reply, while NBD_CMD_DISC does not.
This patch merely adds the missing reply to NBD_OPT_ABORT and teaches
the client to recognize server errors. Actually teaching the server
to send NBD_REP_ERR_SHUTDOWN or ESHUTDOWN would require knowing that
the server has been requested to shut down soon (maybe we could do
that by installing a SIGINT handler in qemu-nbd, which transitions
from RUNNING to a new state that waits for the client to react,
rather than just out-right quitting - but that's a bigger task for
another day).
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-15-git-send-email-eblake@redhat.com>
[Move dummy ESHUTDOWN to include/qemu/osdep.h. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The NBD Protocol allows the server and client to mutually agree
on a shorter handshake (omit the 124 bytes of reserved 0), via
the server advertising NBD_FLAG_NO_ZEROES and the client
acknowledging with NBD_FLAG_C_NO_ZEROES (only possible in
newstyle, whether or not it is fixed newstyle). It doesn't
shave much off the wire, but we might as well implement it.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alex Bligh <alex@alex.org.uk>
Message-Id: <1476469998-28592-13-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Rather than open-coding each option request, it's easier to
have common helper functions do the work. That in turn requires
having convenient packed types for handling option requests
and replies.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-9-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Our coding convention prefers CamelCase names, and we already
have other existing structs with NBDFoo naming. Let's be
consistent, before later patches add even more structs.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-6-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Current upstream NBD documents that requests have a 16-bit flags,
followed by a 16-bit type integer; although older versions mentioned
only a 32-bit field with masking to find flags. Since the protocol
is in network order (big-endian over the wire), the ABI is unchanged;
but dealing with the flags as a separate field rather than masking
will make it easier to add support for upcoming NBD extensions that
increase the number of both flags and commands.
Improve some comments in nbd.h based on the current upstream
NBD protocol (https://github.com/yoe/nbd/blob/master/doc/proto.md),
and touch some nearby code to keep checkpatch.pl happy.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-3-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The NBD protocol allows servers to advertise a human-readable
description alongside an export name during NBD_OPT_LIST. Add
an option to pass through the user's string to the NBD client.
Doing this also makes it easier to test commit 200650d4, which
is the client counterpart of receiving the description.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1476469998-28592-2-git-send-email-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(Trivial)
Fix wrong function names in documentation.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Message-id: 1477584421-1399-8-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
To make it a little more obvious which functions are intended to be
public interface and which are intended to be for use only by jobs
themselves, split the interface into "public" and "private" files.
Convert blockjobs (e.g. block/backup) to using the private interface.
Leave blockdev and others on the public interface.
There are remaining uses of private state by qemu-img, and several
cases in blockdev.c and block/io.c where we grab job->blk for the
purposes of acquiring an AIOContext.
These will be corrected in future patches.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Message-id: 1477584421-1399-7-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
BlockJobs will begin hiding their state in preparation for some
refactorings anyway, so let's internalize the user_pause mechanism
instead of leaving it to callers to correctly manage.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Message-id: 1477584421-1399-6-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
There's no reason to leave this to blockdev; we can do it in blockjobs
directly and get rid of an extra callback for most users.
All non-internal events, even those created outside of QMP, will
consistently emit events.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Message-id: 1477584421-1399-5-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
Bubble up the internal interface to commit and backup jobs, then switch
replication tasks over to using this methodology.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Message-id: 1477584421-1399-4-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
Add the ability to create jobs without an ID.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Message-id: 1477584421-1399-3-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
If jobs are not created directly by the user, do not allow them to be
seen by the user/management utility. At the moment, 'internal' jobs are
those that do not have an ID. As of this patch it is impossible to
create such jobs.
Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 1477584421-1399-2-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
When a block job is created on a certain BlockDriverState, operations
are blocked there while the job exists. However, some block jobs may
involve additional BDSs, which must be blocked separately when the job
is created and unblocked manually afterwards.
This patch adds block_job_add_bdrv(), that simplifies this process by
keeping a list of BDSs that are involved in the specified block job.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_drain_all() doesn't allow the caller to do anything after all
pending requests have been completed but before block jobs are
resumed.
This patch splits bdrv_drain_all() into _begin() and _end() for that
purpose. It also adds aio_{disable,enable}_external() calls to disable
external clients in the meantime.
An important restriction of this split is that no new block jobs or
BlockDriverStates can be created between the bdrv_drain_all_begin()
and bdrv_drain_all_end() calls. This is not a concern now because
we'll only be using this in bdrv_reopen_multiple(), but it must be
dealt with if we ever have other uses cases in the future.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
It is simpler and a bit faster, and QEMU does not need the contention
callbacks (and thus the fairness) anymore.
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-21-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
This is the first step towards having fine-grained critical sections in
dataplane threads, which will resolve lock ordering problems between
address_space_* functions (which need the BQL when doing MMIO, even
after we complete RCU-based dispatch) and the AioContext.
Because AioContext does not use contention callbacks anymore, the
unit test has to be changed.
Previously applied as a0710f7995 and
then reverted.
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-19-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
aio_poll is not thread safe; for example bdrv_drain can hang if
the last in-flight I/O operation is completed in the I/O thread after
the main thread has checked bs->in_flight.
The bug remains latent as long as all of it is called within
aio_context_acquire/aio_context_release, but this will change soon.
To fix this, if bdrv_drain is called from outside the I/O thread,
signal the main AioContext through a dummy bottom half. The event
loop then only runs in the I/O thread.
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-18-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
After the next patch bdrv_drain_all will have to be called without holding any
AioContext. Prepare to do this by adding an AioContext argument to
bdrv_reopen_multiple.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-15-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
This will be used by BDRV_POLL_WHILE (and thus by bdrv_drain)
to choose how to wait for I/O completion.
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-12-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
We want the BDS event loop to run exclusively in the iothread that
owns the BDS's AioContext. This macro will provide the synchronization
between the two event loops; for now it just wraps the common idiom
of a while loop around aio_poll.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-Id: <1477565348-5458-8-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Unlike tracked_requests, this field also counts throttled requests,
and remains non-zero if an AIO operation needs a BH to be "really"
completed.
With this change, it is no longer necessary to have a dummy
BdrvTrackedRequest for requests that are never serialising, and
it is no longer necessary to poll the AioContext once after
bdrv_requests_pending(bs) returns false.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-Id: <1477565348-5458-5-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
This is required to decouple block jobs from running in an
AioContext. With multiqueue block devices, a BlockDriverState
does not really belong to a single AioContext.
The solution is to first wait until all I/O operations are
complete; then loop in the main thread for the block job to
complete entirely.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-Id: <1477565348-5458-3-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
