At least the simple trace backend works by spawning a helper thread,
and setting up an atexit() handler that coordinates completion with
the helper thread. But since atexit registrations survive fork() but
helper threads do not, this means that qemu-nbd configured to use the
simple trace will deadlock waiting for a thread that no longer exists
when it has daemonized.
Better is to follow the example of vl.c: don't call any setup
functions that might spawn helper threads until we are in the final
process that will be doing the work worth tracing.
Tested by configuring with --enable-trace-backends=simple, then running
qemu-nbd --fork --trace=nbd_\*,file=qemu-nbd.trace -f raw -r README.rst
followed by `nbdinfo nbd://localhost`, and observing that the trace
file is now created without hanging.
Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20250227220625.870246-2-eblake@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Although defaulting the handshake limit to 10 seconds was a nice QoI
change to weed out intentionally slow clients, it can interfere with
integration testing done with manual NBD_OPT commands over 'nbdsh
--opt-mode'. Expose a command line option to allow the user to alter
the timeout away from the default. This option is unlikely to be used
in enough scenarios to warrant a short option letter.
The option --handshake-limit intentionally differs from the name of
the constant added in commit fb1c2aaa98 (limit instead of max_secs)
and the QMP name to be added in the next commit; this is because
typing a longer command-line name is undesirable and there is
sufficient --help text to document the units.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20250203222722.650694-5-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
The general expectation is that header files should follow the same
file/path naming scheme as the corresponding source file. There are
various historical exceptions to this practice in QEMU, with one of
the most notable being the include/qapi/qmp/ directory. Most of the
headers there correspond to source files in qobject/.
This patch corrects most of that inconsistency by creating
include/qobject/ and moving the headers for qobject/ there.
This also fixes MAINTAINERS for include/qapi/qmp/dispatch.h:
scripts/get_maintainer.pl now reports "QAPI" instead of "No
maintainers found".
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com> #s390x
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20241118151235.2665921-2-armbru@redhat.com>
[Rebased]
Headers in include/sysemu/ are not only related to system
*emulation*, they are also used by virtualization. Rename
as system/ which is clearer.
Files renamed manually then mechanical change using sed tool.
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Lei Yang <leiyang@redhat.com>
Message-Id: <20241203172445.28576-1-philmd@linaro.org>
Upcoming patches to fix a CVE need to track an opaque pointer passed
in by the owner of a client object, as well as request for a time
limit on how fast negotiation must complete. Prepare for that by
changing the signature of nbd_client_new() and adding an accessor to
get at the opaque pointer, although for now the two servers
(qemu-nbd.c and blockdev-nbd.c) do not change behavior even though
they pass in a new default timeout value.
Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20240807174943.771624-11-eblake@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
[eblake: s/LIMIT/MAX_SECS/ as suggested by Dan]
Signed-off-by: Eric Blake <eblake@redhat.com>
Touch up a comment with the wrong type name, and an over-long line,
both noticed while working on upcoming patches.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20240807174943.771624-10-eblake@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
This is the big patch that removes
aio_context_acquire()/aio_context_release() from the block layer and
affected block layer users.
There isn't a clean way to split this patch and the reviewers are likely
the same group of people, so I decided to do it in one patch.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Message-ID: <20231205182011.1976568-7-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Allow a client to request a subset of negotiated meta contexts. For
example, a client may ask to use a single connection to learn about
both block status and dirty bitmaps, but where the dirty bitmap
queries only need to be performed on a subset of the disk; forcing the
server to compute that information on block status queries in the rest
of the disk is wasted effort (both at the server, and on the amount of
traffic sent over the wire to be parsed and ignored by the client).
Qemu as an NBD client never requests to use more than one meta
context, so it has no need to use block status payloads. Testing this
instead requires support from libnbd, which CAN access multiple meta
contexts in parallel from a single NBD connection; an interop test
submitted to the libnbd project at the same time as this patch
demonstrates the feature working, as well as testing some corner cases
(for example, when the payload length is longer than the export
length), although other corner cases (like passing the same id
duplicated) requires a protocol fuzzer because libnbd is not wired up
to break the protocol that badly.
This also includes tweaks to 'qemu-nbd --list' to show when a server
is advertising the capability, and to the testsuite to reflect the
addition to that output.
Of note: qemu will always advertise the new feature bit during
NBD_OPT_INFO if extended headers have alreay been negotiated
(regardless of whether any NBD_OPT_SET_META_CONTEXT negotiation has
occurred); but for NBD_OPT_GO, qemu only advertises the feature if
block status is also enabled (that is, if the client does not
negotiate any contexts, then NBD_CMD_BLOCK_STATUS cannot be used, so
the feature is not advertised).
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230925192229.3186470-26-eblake@redhat.com>
[eblake: fix logic to reject unnegotiated contexts]
Signed-off-by: Eric Blake <eblake@redhat.com>
All the pieces are in place for a client to finally request extended
headers. Note that we must not request extended headers when qemu-nbd
is used to connect to the kernel module (as nbd.ko does not expect
them, but expects us to do the negotiation in userspace before handing
the socket over to the kernel), but there is no harm in all other
clients requesting them.
Extended headers are not essential to the information collected during
'qemu-nbd --list', but probing for it gives us one more piece of
information in that output. Update the iotests affected by the new
line of output.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230925192229.3186470-23-eblake@redhat.com>
Address all compiler complaints from -Wshadow in qemu-nbd. Several
instances of 'int ret' became shadows when commit 4fbec260 added 'ret'
at a higher scope in main. More interesting was the 'void *ret'
capturing the result of a pthread; where we were conceptually doing
'(void*)(intptr_t)EXIT_FAILURE != NULL' which just feels wrong (even
though it happens to compile correctly), so it was worth a better
cleanup.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230922205019.2755352-2-eblake@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
The upcoming patches for 64-bit extensions requires various points in
the protocol to make decisions based on what was negotiated. While we
could easily add a 'bool extended_headers' alongside the existing
'bool structured_reply', this does not scale well if more modes are
added in the future. Better is to expose the mode enum added in the
recent commit bfe04d0a7d out to a wider use in the code base.
Where the code previously checked for structured_reply being set or
clear, it now prefers checking for an inequality; this works because
the nodes are in a continuum of increasing abilities, and allows us to
touch fewer places if we ever insert other modes in the middle of the
enum. There should be no semantic change in this patch.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230829175826.377251-20-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Closing stderr earlier is good for daemonized qemu-nbd under ssh
earlier, but breaks the case where -v is being used to track what is
happening in the server, as in iotest 233.
When we know we are verbose, we should preserve original stderr and
restore it once the setup stage is done. This commit restores the
original behavior with -v option. In this case original output
inside the test is kept intact.
Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
CC: Hanna Reitz <hreitz@redhat.com>
CC: Mike Maslenkin <mike.maslenkin@gmail.com>
Fixes: 5c56dd27a2 ("qemu-nbd: fix regression with qemu-nbd --fork run over ssh")
Message-ID: <20230906093210.339585-7-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
[eblake: fix build by avoiding stderr as struct member name]
Signed-off-by: Eric Blake <eblake@redhat.com>
Move the code from main() and nbd_client_thread() into the specific
helper. This code is going to be grown.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230906093210.339585-6-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We pass other parameters into nbd_client_thread() in this way. This patch
makes the code more consistent.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230906093210.339585-5-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We pass other parameters into nbd_client_thread() in this way. This patch
makes the code more consistent.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230906093210.339585-4-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: Note that this also cleans up a -Wshadow issue, first
introduced in e5b815b0]
Signed-off-by: Eric Blake <eblake@redhat.com>
This patch also drops definition of some locals in main() to avoid
useless data copy.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230906093210.339585-3-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
This error happens if we are not able to close the pipe to the
parent (to trace errors in the child process) and assign stderr to
/dev/null as required by the daemonizing convention.
Signed-off-by: Denis V. Lunev <den@openvz.org>
Suggested-by: Eric Blake <eblake@redhat.com>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230906093210.339585-2-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: commit message grammar]
Signed-off-by: Eric Blake <eblake@redhat.com>
aio_context is always NULL, so drop it.
Suggested-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20230830224802.493686-2-stefanha@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Unfortunately
commit 03b6762144
Author: Denis V. Lunev <den@openvz.org>
Date: Mon Jul 17 16:55:40 2023 +0200
qemu-nbd: pass structure into nbd_client_thread instead of plain char*
has introduced a regression. struct NbdClientOpts resides on stack inside
'if' block. This specifically means that this stack space could be reused
once the execution will leave that block of the code.
This means that parameters passed into nbd_client_thread could be
overwritten at any moment.
The patch moves the data to the namespace of main() function effectively
preserving it for the whole process lifetime.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
CC: <qemu-stable@nongnu.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230727105828.324314-1-den@openvz.org>
Signed-off-by: Eric Blake <eblake@redhat.com>
Pass 'verbose' to nbd_client_thread() inside NbdClientOpts which looks
a little bit cleaner and make it bool as it is used as bool actually.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230717202520.236999-1-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Fail on error, we are in trouble.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230717145544.194786-6-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: avoid intermediate variable]
Signed-off-by: Eric Blake <eblake@redhat.com>
We are trying to temporarily redirect stderr of daemonized process to
a pipe to report a error and get failed. In that case we could not
use error_report() helper, but should write the message directly into
the problematic pipe.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230717145544.194786-4-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: rearrange patch series, fix typo]
Signed-off-by: Eric Blake <eblake@redhat.com>
errno has been overwritten by dup2() just below qemu_daemon() and thus
improperly returned to the caller. Fix accordingly.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230717145544.194786-5-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: reorder patch series]
Signed-off-by: Eric Blake <eblake@redhat.com>
Commit e6df58a557
Author: Hanna Reitz <hreitz@redhat.com>
Date: Wed May 8 23:18:18 2019 +0200
qemu-nbd: Do not close stderr
has introduced an interesting regression. Original behavior of
ssh somehost qemu-nbd /home/den/tmp/file -f raw --fork
was the following:
* qemu-nbd was started as a daemon
* the command execution is done and ssh exited with success
The patch has changed this behavior and 'ssh' command now hangs forever.
According to the normal specification of the daemon() call, we should
endup with STDERR pointing to /dev/null. That should be done at the
very end of the successful startup sequence when the pipe to the
bootstrap process (used for diagnostics) is no longer needed.
This could be achived in the same way as done for 'qemu-nbd -c' case.
That was commit 0eaf453e, also fixing up e6df58a5. STDOUT copying to
STDERR does the trick.
This also leads to proper 'ssh' connection closing which fixes my
original problem.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
CC: Hanna Reitz <hreitz@redhat.com>
CC: <qemu-stable@nongnu.org>
Message-ID: <20230717145544.194786-3-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We are going to pass additional flag inside next patch.
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Eric Blake <eblake@redhat.com>
CC: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
CC: <qemu-stable@nongnu.org>
Message-ID: <20230717145544.194786-2-den@openvz.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
The function documentation already says that all callers must hold the
main AioContext lock, but not all of them do. This can cause assertion
failures when functions called by bdrv_open() try to drop the lock. Fix
a few more callers to take the lock before calling bdrv_open().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230525124713.401149-4-kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The has_FOO for pointer-valued FOO are redundant, except for arrays.
They are also a nuisance to work with. Recent commit "qapi: Start to
elide redundant has_FOO in generated C" provided the means to elide
them step by step. This is the step for qapi/block*.json.
Said commit explains the transformation in more detail.
There is one instance of the invariant violation mentioned there:
qcow2_signal_corruption() passes false, "" when node_name is an empty
string. Take care to pass NULL then.
The previous two commits cleaned up two more.
Additionally, helper bdrv_latency_histogram_stats() loses its output
parameters and returns a value instead.
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Hanna Reitz <hreitz@redhat.com>
Cc: qemu-block@nongnu.org
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20221104160712.3005652-11-armbru@redhat.com>
[Fixes for #ifndef LIBRBD_SUPPORTS_ENCRYPTION and MacOS squashed in]
The next patch wants to adjust whether the NBD server code advertises
MULTI_CONN based on whether it is known if the server limits to
exactly one client. For a server started by QMP, this information is
obtained through nbd_server_start (which can support more than one
export); but for qemu-nbd (which supports exactly one export), it is
controlled only by the command-line option -e/--shared. Since we
already have a hook function used by qemu-nbd, it's easiest to just
alter its signature to fit our needs.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20220512004924.417153-2-eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
GLib g_unix_open_pipe() is essentially like qemu_pipe(), available since
2.30.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Hi all! Current logic of relying on search through backing chain is not
safe neither convenient.
Sometimes it leads to necessity of extra bitmap copying. Also, we are
going to add "snapshot-access" driver, to access some snapshot state
through NBD. And this driver is not formally a filter, and of course
it's not a COW format driver. So, searching through backing chain will
not work. Instead of widening the workaround of bitmap searching, let's
extend the interface so that user can select bitmap precisely.
Note, that checking for bitmap active status is not copied to the new
API, I don't see a reason for it, user should understand the risks. And
anyway, bitmap from other node is unrelated to this export being
read-only or read-write.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@openvz.org>
Message-Id: <20220314213226.362217-3-v.sementsov-og@mail.ru>
[eblake: Adjust S-o-b to Vladimir's new email, with permission]
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Do not force exit within qemu_set_log; return bool and pass
an Error value back up the stack as per usual.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220417183019.755276-5-richard.henderson@linaro.org>
The TLS usage for NBD was restricted to IP sockets because validating
x509 certificates requires knowledge of the hostname that the client
is connecting to.
TLS does not have to use x509 certificates though, as PSK (pre-shared
keys) provide an alternative credential option. These have no
requirement for a hostname and can thus be trivially used for UNIX
sockets.
Furthermore, with the ability to overide the default hostname for
TLS validation in the previous patch, it is now also valid to want
to use x509 certificates with FD passing and UNIX sockets.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220304193610.3293146-6-berrange@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
When using the --list option, qemu-nbd acts as an NBD client rather
than a server. As such when using TLS, it has a need to validate
the server certificate. This adds a --tls-hostname option which can
be used to override the default hostname used for certificate
validation.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220304193610.3293146-5-berrange@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Under SELinux, Unix domain sockets have two labels. One is on the
disk and can be set with commands such as chcon(1). There is a
different label stored in memory (called the process label). This can
only be set by the process creating the socket. When using SELinux +
SVirt and wanting qemu to be able to connect to a qemu-nbd instance,
you must set both labels correctly first.
For qemu-nbd the options to set the second label are awkward. You can
create the socket in a wrapper program and then exec into qemu-nbd.
Or you could try something with LD_PRELOAD.
This commit adds the ability to set the label straightforwardly on the
command line, via the new --selinux-label flag. (The name of the flag
is the same as the equivalent nbdkit option.)
A worked example showing how to use the new option can be found in
this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
[eblake: rebase to configure changes, reject --selinux-label if it is
not compiled in or not used on a Unix socket]
Note that we may relax some of these restrictions at a later date,
such as making it possible to label a TCP socket, although it may be
smarter to do so as a generic QMP action rather than more one-off
command lines in qemu-nbd.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20211115202944.615966-1-eblake@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
[eblake: adjust meson output as suggested by thuth]
Signed-off-by: Eric Blake <eblake@redhat.com>
Both qemu and qemu-img use writeback cache mode by default, which is
already documented in qemu(1). qemu-nbd uses writethrough cache mode by
default, and the default cache mode is not documented.
According to the qemu-nbd(8):
--cache=CACHE
The cache mode to be used with the file. See the
documentation of the emulator's -drive cache=... option for
allowed values.
qemu(1) says:
The default mode is cache=writeback.
So users have no reason to assume that qemu-nbd is using writethough
cache mode. The only hint is the painfully slow writing when using the
defaults.
Looking in git history, it seems that qemu used writethrough in the past
to support broken guests that did not flush data properly, or could not
flush due to limitations in qemu. But qemu-nbd clients can use
NBD_CMD_FLUSH to flush data, so using writethrough does not help anyone.
Change the default cache mode to writback, and document the default and
available values properly in the online help and manual.
With this change converting image via qemu-nbd is 3.5 times faster.
$ qemu-img create dst.img 50g
$ qemu-nbd -t -f raw -k /tmp/nbd.sock dst.img
Before this change:
$ hyperfine -r3 "./qemu-img convert -p -f raw -O raw -T none -W fedora34.img nbd+unix:///?socket=/tmp/nbd.sock"
Benchmark #1: ./qemu-img convert -p -f raw -O raw -T none -W fedora34.img nbd+unix:///?socket=/tmp/nbd.sock
Time (mean ± σ): 83.639 s ± 5.970 s [User: 2.733 s, System: 6.112 s]
Range (min … max): 76.749 s … 87.245 s 3 runs
After this change:
$ hyperfine -r3 "./qemu-img convert -p -f raw -O raw -T none -W fedora34.img nbd+unix:///?socket=/tmp/nbd.sock"
Benchmark #1: ./qemu-img convert -p -f raw -O raw -T none -W fedora34.img nbd+unix:///?socket=/tmp/nbd.sock
Time (mean ± σ): 23.522 s ± 0.433 s [User: 2.083 s, System: 5.475 s]
Range (min … max): 23.234 s … 24.019 s 3 runs
Users can avoid the issue by using --cache=writeback[1] but the defaults
should give good performance for the common use case.
[1] https://bugzilla.redhat.com/1990656
Signed-off-by: Nir Soffer <nsoffer@redhat.com>
Message-Id: <20210813205519.50518-1-nsoffer@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>
We did this with scripts/coccinelle/use-error_fatal.cocci before, in
commit 50beeb6809 and 007b06578a. This commit cleans up rarer
variations that don't seem worth matching with Coccinelle.
Cc: Thomas Huth <thuth@redhat.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Juan Quintela <quintela@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20210720125408.387910-2-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Avoid accessing QCryptoTLSCreds internals by using
the qcrypto_tls_creds_check_endpoint() helper.
Tested-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
This switches qemu-nbd from a QemuOpts-based parser for --object to
user_creatable_process_cmdline() which uses a keyval parser and enforces
the QAPI schema.
Apart from being a cleanup, this makes non-scalar properties accessible.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This gives us better feature parity with QMP nbd-server-start, where
max-connections defaults to 0 for unlimited.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210209152759.209074-3-eblake@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Our default of a backlog of 1 connection is rather puny; it gets in
the way when we are explicitly allowing multiple clients (such as
qemu-nbd -e N [--shared], or nbd-server-start with its default
"max-connections":0 for unlimited), but is even a problem when we
stick to qemu-nbd's default of only 1 active client but use -t
[--persistent] where a second client can start using the server once
the first finishes. While the effects are less noticeable on TCP
sockets (since the client can poll() to learn when the server is ready
again), it is definitely observable on Unix sockets, where on Linux, a
client will fail with EAGAIN and no recourse but to sleep an arbitrary
amount of time before retrying if the server backlog is already full.
Since QMP nbd-server-start is always persistent, it now always
requests a backlog of SOMAXCONN; meanwhile, qemu-nbd will request
SOMAXCONN if persistent, otherwise its backlog should be based on the
expected number of clients.
See https://bugzilla.redhat.com/1925045 for a demonstration of where
our low backlog prevents libnbd from connecting as many parallel
clients as it wants.
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
CC: qemu-stable@nongnu.org
Message-Id: <20210209152759.209074-2-eblake@redhat.com>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Move blk_exp_close_all() from bdrv_close() to qemu_cleanup(), before
bdrv_drain_all_begin().
Export drivers may have coroutines yielding at some point in the block
layer, so we need to shut them down before draining the block layer,
as otherwise they may get stuck blk_wait_while_drained().
RHBZ: https://bugzilla.redhat.com/show_bug.cgi?id=1900505
Signed-off-by: Sergio Lopez <slp@redhat.com>
Message-Id: <20210201125032.44713-3-slp@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When the qio_channel_socket_connect_sync() fails
we should goto 'out_socket' label to free the 'sioc' instead of
goto 'out' label.
In addition, there's a lot of redundant code in the successful branch
and the error branch, optimize it.
Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Alex Chen <alex.chen@huawei.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20201208134944.27962-1-alex.chen@huawei.com>
When the qio_channel_socket_connect_sync() fails
we should goto 'out' label to free the 'sioc' instead of return.
Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Alex Chen <alex.chen@huawei.com>
Message-Id: <20201130123651.17543-1-alex.chen@huawei.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
It is not needed, all the callers are just saving what was
retrieved from -trace and trace_init_file can retrieve it
on its own.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20201102115841.4017692-1-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Allow the server to expose an additional metacontext to be requested
by savvy clients. qemu-nbd adds a new option -A to expose the
qemu:allocation-depth metacontext through NBD_CMD_BLOCK_STATUS; this
can also be set via QMP when using block-export-add.
qemu as client is hacked into viewing the key aspects of this new
context by abusing the already-experimental x-dirty-bitmap option to
collapse all depths greater than 2, which results in a tri-state value
visible in the output of 'qemu-img map --output=json' (yes, that means
x-dirty-bitmap is now a bit of a misnomer, but I didn't feel like
renaming it as it would introduce a needless break of back-compat,
even though we make no compat guarantees with x- members):
unallocated (depth 0) => "zero":false, "data":true
local (depth 1) => "zero":false, "data":false
backing (depth 2+) => "zero":true, "data":true
libnbd as client is probably a nicer way to get at the information
without having to decipher such hacks in qemu as client. ;)
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20201027050556.269064-11-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Since 'block-export-add' is new to 5.2, we can still tweak the
interface; there, allowing 'bitmaps':['str'] is nicer than
'bitmap':'str'. This wires up the qapi and qemu-nbd changes to permit
passing multiple bitmaps as distinct metadata contexts that the NBD
client may request, but the actual support for more than one will
require a further patch to the server.
Note that there are no changes made to the existing deprecated
'nbd-server-add' command; this required splitting the QAPI type
BlockExportOptionsNbd, which fortunately does not affect QMP
introspection.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20201027050556.269064-5-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Block exports are used by softmmu, qemu-storage-daemon, and qemu-nbd.
They are not used by other programs and are not otherwise needed in
libblock.
Undo the recent move of blockdev-nbd.c from blockdev_ss into block_ss.
Since bdrv_close_all() (libblock) calls blk_exp_close_all()
(libblockdev) a stub function is required..
Make qemu-nbd.c use signal handling utility functions instead of
duplicating the code. This helps because os-posix.c is in libblockdev
and it depends on a qemu_system_killed() symbol that qemu-nbd.c lacks.
Once we use the signal handling utility functions we also end up
providing the necessary symbol.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20200929125516.186715-4-stefanha@redhat.com
[Fixed s/ndb/nbd/ typo in commit description as suggested by Eric Blake
--Stefan]
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Honoring just SIGTERM on Linux is too weak; we also want to handle
other common signals, and do so even on BSD. Why? Because at least
'qemu-nbd -B bitmap' needs a chance to clean up the in-use bit on
bitmaps when the server is shut down via a signal.
See also: http://bugzilla.redhat.com/1883608
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200930121105.667049-2-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[eblake: apply comment tweak suggested by Vladimir; fix ifdef around
termsig_handler]
Signed-off-by: Eric Blake <eblake@redhat.com>
Eric Blake
Daniel P. Berrangé
Philippe Mathieu-Daudé
Michael Tokarev
Stefan Hajnoczi
Denis V. Lunev
Kevin Wolf
Markus Armbruster
Marc-André Lureau
Vladimir Sementsov-Ogievskiy
Richard Henderson
Richard W.M. Jones
Nir Soffer
Philippe Mathieu-Daudé
Sergio Lopez
Alex Chen
Paolo Bonzini