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>
(cherry picked from commit fb1c2aaa98)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
Unfortunately
commit 03b6762144
(7.2: 6e216d21b5)
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>
(cherry picked from commit e5b815b0de)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: add reference to 6e216d21b5 for 7.2 branch)
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>
(cherry picked from commit 5c56dd27a2)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
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>
(cherry picked from commit 03b6762144)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
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>
The 'writable' option is a basic option that will probably be applicable
to most if not all export types that we will implement. Move it from NBD
to the generic BlockExport layer.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-26-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We'll need an id to identify block exports in monitor commands. This
adds one.
Note that this is different from the 'name' option in the NBD server,
which is the externally visible export name. While block export ids need
to be unique in the whole process, export names must be unique only for
the same server. Different export types or (potentially in the future)
multiple NBD servers can have the same export name externally, but still
need different block export ids internally.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-19-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This adds a function to shut down all block exports, and another one to
shut down the block exports of a single type. The latter is used for now
when stopping the NBD server. As soon as we implement support for
multiple NBD servers, we'll need a per-server list of exports and it
will be replaced by a function using that.
As a side effect, the BlockExport layer has a list tracking all existing
exports now. closed_exports loses its only user and can go away.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-18-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Every block export needs a block node to export, so add a 'node-name'
option to BlockExportOptions and remove the replaced option 'device'
from BlockExportOptionsNbd.
To maintain compatibility in nbd-server-add, BlockExportOptionsNbd needs
to be wrapped by a new type NbdServerAddOptions that adds 'device' back
because nbd-server-add doesn't use the BlockExportOptions base type at
all (so even without changing it to a 'node-name' option in
block-export-add, this compatibility code would be necessary).
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-16-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
With this change, NBD exports are now only created through the
BlockExport interface. This allows us finally to move things from the
NBD layer to the BlockExport layer if they make sense for other export
types, too.
blk_exp_add() returns only a weak reference, so the explicit
nbd_export_put() goes away.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-12-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The export close callback is unused by the built-in NBD server. qemu-nbd
uses it only during shutdown to wait for the unrefed export to actually
go away. It can just use nbd_export_close_all() instead and do without
the callback.
This removes the close callback from nbd_export_new() and makes both
callers of it more similar.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200924152717.287415-11-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
nbd-server-add tries to be convenient and adds two questionable
features that we don't want to share in block-export-add, even for NBD
exports:
1. When requesting a writable export of a read-only device, the export
is silently downgraded to read-only. This should be an error in the
context of block-export-add.
2. When using a BlockBackend name, unplugging the device from the guest
will automatically stop the NBD server, too. This may sometimes be
what you want, but it could also be very surprising. Let's keep
things explicit with block-export-add. If the user wants to stop the
export, they should tell us so.
Move these things into the nbd-server-add QMP command handler so that
they apply only there.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-8-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Instead of implementing qemu-nbd --offset in the NBD code, just put a
raw block node with the requested offset on top of the user image and
rely on that doing the job.
This does not only simplify the nbd_export_new() interface and bring it
closer to the set of options that the nbd-server-add QMP command offers,
but in fact it also eliminates a potential source for bugs in the NBD
code which previously had to add the offset manually in all relevant
places.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200924152717.287415-7-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
clang's C11 atomic_fetch_*() functions only take a C11 atomic type
pointer argument. QEMU uses direct types (int, etc) and this causes a
compiler error when a QEMU code calls these functions in a source file
that also included <stdatomic.h> via a system header file:
$ CC=clang CXX=clang++ ./configure ... && make
../util/async.c:79:17: error: address argument to atomic operation must be a pointer to _Atomic type ('unsigned int *' invalid)
Avoid using atomic_*() names in QEMU's atomic.h since that namespace is
used by <stdatomic.h>. Prefix QEMU's APIs with 'q' so that atomic.h
and <stdatomic.h> can co-exist. I checked /usr/include on my machine and
searched GitHub for existing "qatomic_" users but there seem to be none.
This patch was generated using:
$ git grep -h -o '\<atomic\(64\)\?_[a-z0-9_]\+' include/qemu/atomic.h | \
sort -u >/tmp/changed_identifiers
$ for identifier in $(</tmp/changed_identifiers); do
sed -i "s%\<$identifier\>%q$identifier%g" \
$(git grep -I -l "\<$identifier\>")
done
I manually fixed line-wrap issues and misaligned rST tables.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200923105646.47864-1-stefanha@redhat.com>
Disabling these parts are sufficient to get the qemu-nbd program
compiling in a Windows build.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200825103850.119911-4-berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
The termsig_handler function is used by the client thread handling the
host NBD device connection to do a graceful shutdown. IOW, if we have
disabled NBD device support at compile time, we don't need the SIGTERM
handler. This fixes a build issue for Windows.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200825103850.119911-3-berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Any tool that uses sockets needs to call socket_init() in order to work
on the Windows platform.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200825103850.119911-2-berrange@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Replace
error_report("...: %s", ..., error_get_pretty(err));
by
error_reportf_err(err, "...: ", ...);
One of the replaced messages lacked a colon. Add it.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200505101908.6207-6-armbru@redhat.com>
Close inherited stderr of the parent if fork_process is false.
Otherwise no one will close it. (introduced by e6df58a5)
This only affected 'qemu-nbd -c /dev/nbd0'.
Signed-off-by: Raphael Pour <raphael.pour@hetzner.com>
Message-Id: <d8ddc993-9816-836e-a3de-c6edab9d9c49@hetzner.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: Enhance commit message]
Signed-off-by: Eric Blake <eblake@redhat.com>
The option was deprecated in 4.0.0 (commit 0ae2d546); it's now been
long enough with no complaints to follow through with that process.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200123164650.1741798-3-eblake@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
Qemu as server currently won't accept export names larger than 256
bytes, nor create dirty bitmap names longer than 1023 bytes, so most
uses of qemu as client or server have no reason to get anywhere near
the NBD spec maximum of a 4k limit per string.
However, we weren't actually enforcing things, ignoring when the
remote side violates the protocol on input, and also having several
code paths where we send oversize strings on output (for example,
qemu-nbd --description could easily send more than 4k). Tighten
things up as follows:
client:
- Perform bounds check on export name and dirty bitmap request prior
to handing it to server
- Validate that copied server replies are not too long (ignoring
NBD_INFO_* replies that are not copied is not too bad)
server:
- Perform bounds check on export name and description prior to
advertising it to client
- Reject client name or metadata query that is too long
- Adjust things to allow full 4k name limit rather than previous
256 byte limit
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20191114024635.11363-4-eblake@redhat.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Instead of parsing help options as normal object properties and
returning an error, provide the same help functionality as the system
emulator in qemu-nbd, too.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Commit fe0480d6 and friends added BDRV_REQ_NO_FALLBACK as a way to
avoid wasting time on a preliminary write-zero request that will later
be rewritten by actual data, if it is known that the write-zero
request will use a slow fallback; but in doing so, could not optimize
for NBD. The NBD specification is now considering an extension that
will allow passing on those semantics; this patch updates the new
protocol bits and 'qemu-nbd --list' output to recognize the bit, as
well as the new errno value possible when using the new flag; while
upcoming patches will improve the client to use the feature when
present, and the server to advertise support for it.
The NBD spec recommends (but not requires) that ENOTSUP be avoided for
all but failures of a fast zero (the only time it is mandatory to
avoid an ENOTSUP failure is when fast zero is supported but not
requested during write zeroes; the questionable use is for ENOTSUP to
other actions like a normal write request). However, clients that get
an unexpected ENOTSUP will either already be treating it the same as
EINVAL, or may appreciate the extra bit of information. We were
equally loose for returning EOVERFLOW in more situations than
recommended by the spec, so if it turns out to be a problem in
practice, a later patch can tighten handling for both error codes.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190823143726.27062-3-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[eblake: tweak commit message, also handle EOPNOTSUPP]
When creating a read-only image, we are still advertising support for
TRIM and WRITE_ZEROES to the client, even though the client should not
be issuing those commands. But seeing this requires looking across
multiple functions:
All callers to nbd_export_new() passed a single flag based solely on
whether the export allows writes. Later, we then pass a constant set
of flags to nbd_negotiate_options() (namely, the set of flags which we
always support, at least for writable images), which is then further
dynamically modified with NBD_FLAG_SEND_DF based on client requests
for structured options. Finally, when processing NBD_OPT_EXPORT_NAME
or NBD_OPT_EXPORT_GO we bitwise-or the original caller's flag with the
runtime set of flags we've built up over several functions.
Let's refactor things to instead compute a baseline of flags as soon
as possible which gets shared between multiple clients, in
nbd_export_new(), and changing the signature for the callers to pass
in a simpler bool rather than having to figure out flags. We can then
get rid of the 'myflags' parameter to various functions, and instead
refer to client for everything we need (we still have to perform a
bitwise-OR for NBD_FLAG_SEND_DF during NBD_OPT_EXPORT_NAME and
NBD_OPT_EXPORT_GO, but it's easier to see what is being computed).
This lets us quit advertising senseless flags for read-only images, as
well as making the next patch for exposing FAST_ZERO support easier to
write.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190823143726.27062-2-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
[eblake: improve commit message, update iotest 223]
The NBD specification defines NBD_FLAG_CAN_MULTI_CONN, which can be
advertised when the server promises cache consistency between
simultaneous clients (basically, rules that determine what FUA and
flush from one client are able to guarantee for reads from another
client). When we don't permit simultaneous clients (such as qemu-nbd
without -e), the bit makes no sense; and for writable images, we
probably have a lot more work before we can declare that actions from
one client are cache-consistent with actions from another. But for
read-only images, where flush isn't changing any data, we might as
well advertise multi-conn support. What's more, advertisement of the
bit makes it easier for clients to determine if 'qemu-nbd -e' was in
use, where a second connection will succeed rather than hang until the
first client goes away.
This patch affects qemu as server in advertising the bit. We may want
to consider patches to qemu as client to attempt parallel connections
for higher throughput by spreading the load over those connections
when a server advertises multi-conn, but for now sticking to one
connection per nbd:// BDS is okay.
See also: https://bugzilla.redhat.com/1708300
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190815185024.7010-1-eblake@redhat.com>
[eblake: tweak blockdev-nbd.c to not request shared when writable,
fix iotest 233]
Reviewed-by: John Snow <jsnow@redhat.com>
No reason to use blocking channel for negotiation and we'll benefit in
further reconnect feature, as qio_channel reads and writes will do
qemu_coroutine_yield while waiting for io completion.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190618114328.55249-3-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We kept old_stderr specifically so we could keep emitting error message
on stderr. However, qemu_daemon() closes stderr. Therefore, we need to
dup() stderr to old_stderr before invoking qemu_daemon().
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190508211820.17851-4-mreitz@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
