The next commit will add support for the optional extension
NBD_CMD_FLAG_PAYLOAD during NBD_CMD_BLOCK_STATUS, where the client can
request that the server only return a subset of negotiated contexts,
rather than all contexts. To make that task easier, this patch
populates the list of contexts to return on a per-command basis (for
now, identical to the full set of negotiated contexts).
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230925192229.3186470-25-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Peform several minor refactorings of how the list of negotiated meta
contexts is managed, to make upcoming patches easier: Promote the
internal type NBDExportMetaContexts to the public opaque type
NBDMetaContexts, and mark exp const. Use a shorter member name in
NBDClient. Hoist calls to nbd_check_meta_context() earlier in their
callers, as the number of negotiated contexts may impact the flags
exposed in regards to an export, which in turn requires a new
parameter. Drop a redundant parameter to nbd_negotiate_meta_queries.
No semantic change intended on the success path; on the failure path,
dropping context in nbd_check_meta_export even when reporting an error
is safer.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230925192229.3186470-24-eblake@redhat.com>
Update the client code to be able to send an extended request, and
parse an extended header from the server. Note that since we reject
any structured reply with a too-large payload, we can always normalize
a valid header back into the compact form, so that the caller need not
deal with two branches of a union. Still, until a later patch lets
the client negotiate extended headers, the code added here should not
be reached. Note that because of the different magic numbers, it is
just as easy to trace and then tolerate a non-compliant server sending
the wrong header reply as it would be to insist that the server is
compliant.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230925192229.3186470-21-eblake@redhat.com>
[eblake: fix trace format]
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Widen the length field of NBDRequest to 64-bits, although we can
assert that all current uses are still under 32 bits: either because
of NBD_MAX_BUFFER_SIZE which is even smaller (and where size_t can
still be appropriate, even on 32-bit platforms), or because nothing
ever puts us into NBD_MODE_EXTENDED yet (and while future patches will
allow larger transactions, the lengths in play here are still capped
at 32-bit). There are no semantic changes, other than a typo fix in a
couple of error messages.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230829175826.377251-23-eblake@redhat.com>
[eblake: fix assertion bug in nbd_co_send_simple_reply]
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Add the constants and structs necessary for later patches to start
implementing the NBD_OPT_EXTENDED_HEADERS extension in both the client
and server, matching recent upstream nbd.git (through commit
e6f3b94a934). This patch does not change any existing behavior, but
merely sets the stage for upcoming patches.
This patch does not change the status quo that neither the client nor
server use a packed-struct representation for the request header.
While most of the patch adds new types, there is also some churn for
renaming the existing NBDExtent to NBDExtent32 to contrast it with
NBDExtent64, which I thought was a nicer name than NBDExtentExt.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230829175826.377251-22-eblake@redhat.com>
Once the 64-bit headers extension is enabled, the data layout we send
over the wire for a client request depends on the mode negotiated with
the server. Rather than adding a parameter to nbd_send_request, we
can add a member to struct NBDRequest, since it already does not
reflect on-wire format. Some callers initialize it directly; many
others rely on a common initialization point during
nbd_co_send_request(). At this point, there is no semantic change.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Message-ID: <20230829175826.377251-21-eblake@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>
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>
Deciphering the hard-coded list of integer return values from
nbd_start_negotiate() will only get more confusing when adding support
for 64-bit extended headers. Better is to name things in an enum.
Although the function in question is private to client.c, putting the
enum in a public header and including an enum-to-string conversion
will allow its use in more places in upcoming patches.
The enum is intentionally laid out so that operators like <= can be
used to group multiple modes with similar characteristics, and where
the least powerful mode has value 0, even though this patch does not
exploit that. No semantic change intended.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230608135653.2918540-9-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Externally, libnbd exposed the 64-bit opaque marker for each client
NBD packet as the "cookie", because it was less confusing when
contrasted with 'struct nbd_handle *' holding all libnbd state. It
also avoids confusion between the noun 'handle' as a way to identify a
packet and the verb 'handle' for reacting to things like signals.
Upstream NBD changed their spec to favor the name "cookie" based on
libnbd's recommendations[1], so we can do likewise.
[1] https://github.com/NetworkBlockDevice/nbd/commit/ca4392eb2b
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230608135653.2918540-6-eblake@redhat.com>
[eblake: typo fix]
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Upstream NBD now documents[1] an extension that supports 64-bit effect
lengths in requests. As part of that extension, the size of the reply
headers will change in order to permit a 64-bit length in the reply
for symmetry[2]. Additionally, where the reply header is currently 16
bytes for simple reply, and 20 bytes for structured reply; with the
extension enabled, there will only be one extended reply header, of 32
bytes, with both structured and extended modes sending identical
payloads for chunked replies.
Since we are already wired up to use iovecs, it is easiest to allow
for this change in header size by splitting each structured reply
across multiple iovecs, one for the header (which will become wider in
a future patch according to client negotiation), and the other(s) for
the chunk payload, and removing the header from the payload struct
definitions. Rename the affected functions with s/structured/chunk/
to make it obvious that the code will be reused in extended mode.
Interestingly, the client side code never utilized the packed types,
so only the server code needs to be updated.
[1] https://github.com/NetworkBlockDevice/nbd/blob/extension-ext-header/doc/proto.md
as of NBD commit e6f3b94a934
[2] Note that on the surface, this is because some future server might
permit a 4G+ NBD_CMD_READ and need to reply with that much data in one
transaction. But even though the extended reply length is widened to
64 bits, for now the NBD spec is clear that servers will not reply
with more than a maximum payload bounded by the 32-bit
NBD_INFO_BLOCK_SIZE field; allowing a client and server to mutually
agree to transactions larger than 4G would require yet another
extension.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230608135653.2918540-4-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
We had a mix of struct declarations followed by typedefs, and direct
struct definitions as part of a typedef. Pick a single style. Also
float forward declarations of opaque types to the top of the file,
rather than interspersed with function declarations, which will help a
future patch that wants to expose yet another opaque type that will be
referenced in NBDRequest. No semantic impact.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-ID: <20230608135653.2918540-3-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
[eblake: alter patch per mailing list feedback]
Signed-off-by: Eric Blake <eblake@redhat.com>
The inlined nbd_readXX() functions call beXX_to_cpu(), themselves
declared in <qemu/bswap.h>. This fixes when refactoring:
In file included from ../../block/nbd.c:44:
include/block/nbd.h: In function 'nbd_read16':
include/block/nbd.h:383:12: error: implicit declaration of function 'be16_to_cpu' [-Werror=implicit-function-declaration]
383 | *val = be##bits##_to_cpu(*val); \
| ^~
include/block/nbd.h:387:1: note: in expansion of macro 'DEF_NBD_READ_N'
387 | DEF_NBD_READ_N(16) /* Defines nbd_read16(). */
| ^~~~~~~~~~~~~~
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221125175328.48539-1-philmd@linaro.org>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
nbd_co_establish_connection_cancel() cancels a coroutine but is not called
from coroutine context itself, for example in nbd_cancel_in_flight()
and in timer callbacks reconnect_delay_timer_cb() and open_timer_cb().
Reviewed-by: Alberto Faria <afaria@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220922084924.201610-5-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
According to the NBD spec, a server that advertises
NBD_FLAG_CAN_MULTI_CONN promises that multiple client connections will
not see any cache inconsistencies: when properly separated by a single
flush, actions performed by one client will be visible to another
client, regardless of which client did the flush.
We always satisfy these conditions in qemu - even when we support
multiple clients, ALL clients go through a single point of reference
into the block layer, with no local caching. The effect of one client
is instantly visible to the next client. Even if our backend were a
network device, we argue that any multi-path caching effects that
would cause inconsistencies in back-to-back actions not seeing the
effect of previous actions would be a bug in that backend, and not the
fault of caching in qemu. As such, it is safe to unconditionally
advertise CAN_MULTI_CONN for any qemu NBD server situation that
supports parallel clients.
Note, however, that we don't want to advertise CAN_MULTI_CONN when we
know that a second client cannot connect (for historical reasons,
qemu-nbd defaults to a single connection while nbd-server-add and QMP
commands default to unlimited connections; but we already have
existing means to let either style of NBD server creation alter those
defaults). This is visible by no longer advertising MULTI_CONN for
'qemu-nbd -r' without -e, as in the iotest nbd-qemu-allocation.
The harder part of this patch is setting up an iotest to demonstrate
behavior of multiple NBD clients to a single server. It might be
possible with parallel qemu-io processes, but I found it easier to do
in python with the help of libnbd, and help from Nir and Vladimir in
writing the test.
Signed-off-by: Eric Blake <eblake@redhat.com>
Suggested-by: Nir Soffer <nsoffer@redhat.com>
Suggested-by: Vladimir Sementsov-Ogievskiy <v.sementsov-og@mail.ru>
Message-Id: <20220512004924.417153-3-eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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>
In
commit a71d597b98
Author: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Date: Thu Jun 10 13:08:00 2021 +0300
block/nbd: reuse nbd_co_do_establish_connection() in nbd_open()
the use of the 'hostname' field from the BDRVNBDState struct was
lost, and 'nbd_connect' just hardcoded it to match the IP socket
address. This was a harmless bug at the time since we block use
with anything other than IP sockets.
Shortly though, we want to allow the caller to override the hostname
used in the TLS certificate checks. This is to allow for TLS
when doing port forwarding or tunneling. Thus we need to reinstate
the passing along of the 'hostname'.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220304193610.3293146-3-berrange@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We'll need a possibility of non-blocking nbd_co_establish_connection(),
so that it returns immediately, and it returns success only if a
connections was previously established in background.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210610100802.5888-30-vsementsov@virtuozzo.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
block/nbd doesn't need underlying sioc channel anymore. So, we can
update nbd/client-connection interface to return only one top-most io
channel, which is more straight forward.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210610100802.5888-27-vsementsov@virtuozzo.com>
[eblake: squash in Vladimir's fixes for uninit usage caught by clang]
Signed-off-by: Eric Blake <eblake@redhat.com>
Add an option for a thread to retry connecting until it succeeds. We'll
use nbd/client-connection both for reconnect and for initial connection
in nbd_open(), so we need a possibility to use same NBDClientConnection
instance to connect once in nbd_open() and then use retry semantics for
reconnect.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210610100802.5888-21-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: grammar tweak]
Signed-off-by: Eric Blake <eblake@redhat.com>
Add arguments and logic to support nbd negotiation in the same thread
after successful connection.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210610100802.5888-20-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
We now have bs-independent connection API, which consists of four
functions:
nbd_client_connection_new()
nbd_client_connection_release()
nbd_co_establish_connection()
nbd_co_establish_connection_cancel()
Move them to a separate file together with NBDClientConnection
structure which becomes private to the new API.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20210610100802.5888-18-vsementsov@virtuozzo.com>
[eblake: comment tweaks]
Signed-off-by: Eric Blake <eblake@redhat.com>
NBD reconnect logic considers the error code from the functions that
read NBD messages to tell if reconnect should be attempted or not: it is
attempted on -EIO, otherwise the client transitions to NBD_CLIENT_QUIT
state (see nbd_channel_error). This error code is propagated from the
primitives like nbd_read.
The problem, however, is that nbd_read itself turns every error into -1
rather than -EIO. As a result, if the NBD server happens to die while
sending the message, the client in QEMU receives less data than it
expects, considers it as a fatal error, and wouldn't attempt
reestablishing the connection.
Fix it by turning every negative return from qio_channel_read_all into
-EIO returned from nbd_read. Apparently that was the original behavior,
but got broken later. Also adjust nbd_readXX to follow.
Fixes: e6798f06a6 ("nbd: generalize usage of nbd_read")
Signed-off-by: Roman Kagan <rvkagan@yandex-team.ru>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20210129073859.683063-4-rvkagan@yandex-team.ru>
Signed-off-by: Eric Blake <eblake@redhat.com>
'qemu-img map' provides a way to determine which extents of an image
come from the top layer vs. inherited from a backing chain. This is
useful information worth exposing over NBD. There is a proposal to
add a QMP command block-dirty-bitmap-populate which can create a dirty
bitmap that reflects allocation information, at which point the
qemu:dirty-bitmap:NAME metadata context can expose that information
via the creation of a temporary bitmap, but we can shorten the effort
by adding a new qemu:allocation-depth metadata context that does the
same thing without an intermediate bitmap (this patch does not
eliminate the need for that proposal, as it will have other uses as
well).
While documenting things, remember that although the NBD protocol has
NBD_OPT_SET_META_CONTEXT, the rest of its documentation refers to
'metadata context', which is a more apt description of what is
actually being used by NBD_CMD_BLOCK_STATUS: the user is requesting
metadata by passing one or more context names. So I also touched up
some existing wording to prefer the term 'metadata context' where it
makes sense.
Note that this patch does not actually enable any way to request a
server to enable this context; that will come in the next patch.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20201027050556.269064-10-eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
There is no real reason any more why nbd_export_new() and
nbd_export_create() should be separate functions. The latter only
performs a few checks before it calls the former.
What makes the current state stand out is that it's the only function in
BlockExportDriver that is not a static function inside nbd/server.c, but
a small wrapper in blockdev-nbd.c that then calls back into nbd/server.c
for the real functionality.
Move all the checks to nbd/server.c and make the resulting function
static to improve readability.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-27-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Every export type will need a BlockBackend, so creating it centrally in
blk_exp_add() instead of the .create driver callback avoids duplication.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-24-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Implement a new QMP command block-export-del and make nbd-server-remove
a wrapper around it.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-21-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>
Instead of letting the driver allocate and return the BlockExport
object, allocate it already in blk_exp_add() and pass it. This allows us
to initialise the generic part before calling into the driver so that
the driver can just use these values instead of having to parse the
options a second time.
For symmetry, move freeing the BlockExport to blk_exp_unref().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-17-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Having a refcount makes sense for all types of block exports. It is also
a prerequisite for keeping a list of all exports at the BlockExport
level.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-14-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>
This is a QMP equivalent of qemu-nbd's --shared option, limiting the
maximum number of clients that can attach at the same time.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200924152717.287415-9-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>
We want to have a common set of commands for all types of block exports.
Currently, this is only NBD, but we're going to add more types.
This patch adds the basic BlockExport and BlockExportDriver structs and
a QMP command block-export-add that creates a new export based on the
given BlockExportOptions.
qmp_nbd_server_add() becomes a wrapper around qmp_block_export_add().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-5-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Move all block export related types and commands from block-core to the
new QAPI module block-export.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200924152717.287415-3-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200924152717.287415-2-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
If we want to check error after errp-function call, we need to
introduce local_err and then propagate it to errp. Instead, use
the ERRP_GUARD() macro, benefits are:
1. No need of explicit error_propagate call
2. No need of explicit local_err variable: use errp directly
3. ERRP_GUARD() leaves errp as is if it's not NULL or
&error_fatal, this means that we don't break error_abort
(we'll abort on error_set, not on error_propagate)
If we want to add some info to errp (by error_prepend() or
error_append_hint()), we must use the ERRP_GUARD() macro.
Otherwise, this info will not be added when errp == &error_fatal
(the program will exit prior to the error_append_hint() or
error_prepend() call). Fix several such cases, e.g. in nbd_read().
This commit is generated by command
sed -n '/^Network Block Device (NBD)$/,/^$/{s/^F: //p}' \
MAINTAINERS | \
xargs git ls-files | grep '\.[hc]$' | \
xargs spatch \
--sp-file scripts/coccinelle/errp-guard.cocci \
--macro-file scripts/cocci-macro-file.h \
--in-place --no-show-diff --max-width 80
Reported-by: Kevin Wolf <kwolf@redhat.com>
Reported-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200707165037.1026246-8-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[ERRP_AUTO_PROPAGATE() renamed to ERRP_GUARD(), and
auto-propagated-errp.cocci to errp-guard.cocci. Commit message
tweaked again.]
Add a --nbd-server option to qemu-storage-daemon to start the built-in
NBD server right away. It maps the arguments for nbd-server-start to the
command line, with the exception that it uses SocketAddress instead of
SocketAddressLegacy: New interfaces shouldn't use legacy types, and the
additional nesting would be nasty on the command line.
Example (only with required options):
--nbd-server addr.type=inet,addr.host=localhost,addr.port=10809
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200224143008.13362-10-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@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>
As long as we limit NBD names to 256 bytes (the bare minimum permitted
by the standard), stack-allocation works for parsing a name received
from the client. But as mentioned in a comment, we eventually want to
permit up to the 4k maximum of the NBD standard, which is too large
for stack allocation; so switch everything in the server to use heap
allocation. For now, there is no change in actually supported name
length.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20191114024635.11363-2-eblake@redhat.com>
[eblake: fix uninit variable compile failure]
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
When iothreads are in use, the failure to grab the aio context results
in an assertion failure when trying to unlock things during blk_unref,
when trying to unlock a mutex that was not locked. In short, all
calls to nbd_export_put need to done while within the correct aio
context. But since nbd_export_put can recursively reach itself via
nbd_export_close, and recursively grabbing the context would deadlock,
we can't do the context grab directly in those functions, but must do
so in their callers.
Hoist the use of the correct aio_context from nbd_export_new() to its
caller qmp_nbd_server_add(). Then tweak qmp_nbd_server_remove(),
nbd_eject_notifier(), and nbd_esport_close_all() to grab the right
context, so that all callers during qemu now own the context before
nbd_export_put() can call blk_unref().
Remaining uses in qemu-nbd don't matter (since that use case does not
support iothreads).
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190917023917.32226-1-eblake@redhat.com>
Reviewed-by: Sergio Lopez <slp@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>
The existing code to convert flag bits into strings looks a bit strange
now, and if we ever add more flags, it will look even stranger. Prevent
that from happening by making it look up the flag names in an array.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20190405191635.25740-1-mreitz@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
As with the previous patch to qemu-nbd, the nbd-server-start QMP command
also needs to be able to specify authorization when enabling TLS encryption.
First the client must create a QAuthZ object instance using the
'object-add' command:
{
'execute': 'object-add',
'arguments': {
'qom-type': 'authz-list',
'id': 'authz0',
'parameters': {
'policy': 'deny',
'rules': [
{
'match': '*CN=fred',
'policy': 'allow'
}
]
}
}
}
They can then reference this in the new 'tls-authz' parameter when
executing the 'nbd-server-start' command:
{
'execute': 'nbd-server-start',
'arguments': {
'addr': {
'type': 'inet',
'host': '127.0.0.1',
'port': '9000'
},
'tls-creds': 'tls0',
'tls-authz': 'authz0'
}
}
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <20190227162035.18543-3-berrange@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Currently any client which can complete the TLS handshake is able to use
the NBD server. The server admin can turn on the 'verify-peer' option
for the x509 creds to require the client to provide a x509 certificate.
This means the client will have to acquire a certificate from the CA
before they are permitted to use the NBD server. This is still a fairly
low bar to cross.
This adds a '--tls-authz OBJECT-ID' option to the qemu-nbd command which
takes the ID of a previously added 'QAuthZ' object instance. This will
be used to validate the client's x509 distinguished name. Clients
failing the authorization check will not be permitted to use the NBD
server.
For example to setup authorization that only allows connection from a client
whose x509 certificate distinguished name is
CN=laptop.example.com,O=Example Org,L=London,ST=London,C=GB
escape the commas in the name and use:
qemu-nbd --object tls-creds-x509,id=tls0,dir=/home/berrange/qemutls,\
endpoint=server,verify-peer=yes \
--object 'authz-simple,id=auth0,identity=CN=laptop.example.com,,\
O=Example Org,,L=London,,ST=London,,C=GB' \
--tls-creds tls0 \
--tls-authz authz0 \
....other qemu-nbd args...
NB: a real shell command line would not have leading whitespace after
the line continuation, it is just included here for clarity.
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <20190227162035.18543-2-berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
[eblake: split long line in --help text, tweak 233 to show that whitespace
after ,, in identity= portion is actually okay]
Signed-off-by: Eric Blake <eblake@redhat.com>
