qemu_nbd_pipe() currently unconditionally reads qemu-nbd's output. That
is not ideal because qemu-nbd may keep stderr open after the parent
process has exited.
Currently, the only user of qemu_nbd_pipe() is 147, which discards the
whole output if the parent process returned success and only evaluates
it on error. Therefore, we can replace qemu_nbd_pipe() by
qemu_nbd_early_pipe() that does the same: Discard the output on success,
and return it on error.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190508211820.17851-3-mreitz@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
To do this, we need to allow creating the NBD server on various ports
instead of a single one (which may not even work if you run just one
instance, because something entirely else might be using that port).
So we just pick a random port in [32768, 32768 + 1024) and try to create
a server there. If that fails, we just retry until something sticks.
For the IPv6 test, we need a different range, though (just above that
one). This is because "localhost" resolves to both 127.0.0.1 and ::1.
This means that if you bind to it, it will bind to both, if possible, or
just one if the other is already in use. Therefore, if the IPv6 test
has already taken [::1]:some_port and we then try to take
localhost:some_port, that will work -- only the second server will be
bound to 127.0.0.1:some_port alone and not [::1]:some_port in addition.
So we have two different servers on the same port, one for IPv4 and one
for IPv6.
But when we then try to connect to the server through
localhost:some_port, we will always end up at the IPv6 one (as long as
it is up), and this may not be the one we want.
Thus, we must make sure not to create an IPv6-only NBD server on the
same port as a normal "dual-stack" NBD server -- which is done by using
distinct port ranges, as explained above.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20181221234750.23577-4-mreitz@redhat.com
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
By default, qemu-nbd binds to 0.0.0.0. However, we then proceed to
connect to "localhost". Usually, this works out fine; but if this test
is run concurrently, some other test function may have bound a different
server to ::1 (on the same port -- you can bind different serves to the
same port, as long as one is on IPv4 and the other on IPv6).
So running qemu-nbd works, it can bind to 0.0.0.0:NBD_PORT. But
potentially a concurrent test has successfully taken [::1]:NBD_PORT. In
this case, trying to connect to "localhost" will lead us to the IPv6
instance, where we do not want to end up.
Fix this by just binding to "localhost". This will make qemu-nbd error
out immediately and not give us cryptic errors later.
(Also, it will allow us to just try a different port as of a future
patch.)
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20181221234750.23577-3-mreitz@redhat.com
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Python 3.4 introduced the inheritable attribute for FDs. At the same
time, it changed the default so that all FDs are not inheritable by
default, that only inheritable FDs are inherited to subprocesses, and
only if close_fds is explicitly set to False.
Adhere to this by setting close_fds to False when working with
subprocesses that may want to inherit FDs, and by trying to
set_inheritable() on FDs that we do want to bequeath to them.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Cleber Rosa <crosa@redhat.com>
Message-Id: <20181022135307.14398-7-mreitz@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20180119135719.24745-4-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
The NBD spec says that clients should not try to write/trim to
an export advertised as read-only by the server. But we failed
to check that, and would allow the block layer to use NBD with
BDRV_O_RDWR even when the server is read-only, which meant we
were depending on the server sending a proper EPERM failure for
various commands, and also exposes a leaky abstraction: using
qemu-io in read-write mode would succeed on 'w -z 0 0' because
of local short-circuiting logic, but 'w 0 0' would send a
request over the wire (where it then depends on the server, and
fails at least for qemu-nbd but might pass for other NBD
implementations).
With this patch, a client MUST request read-only mode to access
a server that is doing a read-only export, or else it will get
a message like:
can't open device nbd://localhost:10809/foo: request for write access conflicts with read-only export
It is no longer possible to even attempt writes over the wire
(including the corner case of 0-length writes), because the block
layer enforces the explicit read-only request; this matches the
behavior of qcow2 when backed by a read-only POSIX file.
Fix several iotests to comply with the new behavior (since
qemu-nbd of an internal snapshot, as well as nbd-server-add over QMP,
default to a read-only export, we must tell blockdev-add/qemu-io to
set up a read-only client).
CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20171108215703.9295-3-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
This is the case in our docker tests, as we use --net=none there. Skip
this method.
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
SocketAddress is a simple union, and simple unions are awkward: they
have their variant members wrapped in a "data" object on the wire, and
require additional indirections in C. I intend to limit its use to
existing external interfaces, and convert all internal interfaces to
SocketAddressFlat.
BlockdevOptionsNbd is an external interface using SocketAddress. We
already use SocketAddressFlat elsewhere in blockdev-add. Replace it
by SocketAddressFlat while we can (it's new in 2.9) for simplicity and
consistency. For example,
{ "execute": "blockdev-add",
"arguments": { "node-name": "foo", "driver": "nbd",
"server": { "type": "inet",
"data": { "host": "localhost",
"port": "12345" } } } }
becomes
{ "execute": "blockdev-add",
"arguments": { "node-name": "foo", "driver": "nbd",
"server": { "type": "inet",
"host": "localhost", "port": "12345" } } }
Since the internal interfaces still take SocketAddress, this requires
conversion function socket_address_crumple(). It'll go away when I
update the interfaces.
Unfortunately, SocketAddress is also visible in -drive since 2.8:
-drive if=none,driver=nbd,server.type=inet,server.data.host=127.0.0.1,server.data.port=12345
Nobody should be using it, as it's fairly new and has never been
documented, so adding still more compatibility gunk to keep it working
isn't worth the trouble. You now have to use
-drive if=none,driver=nbd,server.type=inet,server.host=127.0.0.1,server.port=12345
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-id: 1490895797-29094-9-git-send-email-armbru@redhat.com
[mreitz: Change iotest 147 accordingly]
Because of this interface change, iotest 147 has to be adapted.
Unfortunately, we cannot just flatten all of the addresses because
nbd-server-start still takes a plain SocketAddress. Therefore, we need
both and this is most easily achieved by writing the SocketAddress into
the code and flattening it where necessary.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20170330221243.17333-1-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
It's been a long journey, but here we are.
The supported blockdev-add is not compatible to its experimental
predecessors; bump all Since: tags to 2.9.
x-blockdev-remove-medium, x-blockdev-insert-medium and
x-blockdev-change need a bit more work, so leave them alone for now.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
