bwlp/qemu.git/include/block/nbd.h, branch spice_video_codecs

nbd: remove incorrect coroutine_fn annotations

2022-10-07T10:11:40+00:00

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 Reviewed-by: Eric Blake Signed-off-by: Paolo Bonzini Message-Id: <20220922084924.201610-5-pbonzini@redhat.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf

nbd/server: Allow MULTI_CONN for shared writable exports

2022-05-12T11:10:52+00:00

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 Suggested-by: Nir Soffer Suggested-by: Vladimir Sementsov-Ogievskiy Message-Id: <20220512004924.417153-3-eblake@redhat.com> Signed-off-by: Kevin Wolf

qemu-nbd: Pass max connections to blockdev layer

2022-05-12T11:10:52+00:00

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 Message-Id: <20220512004924.417153-2-eblake@redhat.com> Signed-off-by: Kevin Wolf

block: pass desired TLS hostname through from block driver client

2022-03-07T21:58:42+00:00

In commit a71d597b989fd701b923f09b3c20ac4fcaa55e81 Author: Vladimir Sementsov-Ogievskiy 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 Signed-off-by: Daniel P. Berrangé Message-Id: <20220304193610.3293146-3-berrange@redhat.com> Signed-off-by: Eric Blake

nbd/client-connection: add option for non-blocking connection attempt

2021-06-18T17:21:22+00:00

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 Reviewed-by: Eric Blake Message-Id: <20210610100802.5888-30-vsementsov@virtuozzo.com> Signed-off-by: Eric Blake

nbd/client-connection: return only one io channel

2021-06-18T17:20:53+00:00

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 Reviewed-by: Eric Blake 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

nbd/client-connection: implement connection retry

2021-06-18T15:59:53+00:00

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 Message-Id: <20210610100802.5888-21-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake [eblake: grammar tweak] Signed-off-by: Eric Blake

nbd/client-connection: add possibility of negotiation

2021-06-18T15:59:53+00:00

Add arguments and logic to support nbd negotiation in the same thread after successful connection. Signed-off-by: Vladimir Sementsov-Ogievskiy Message-Id: <20210610100802.5888-20-vsementsov@virtuozzo.com> Reviewed-by: Eric Blake Signed-off-by: Eric Blake

nbd: move connection code from block/nbd to nbd/client-connection

2021-06-18T15:59:53+00:00

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 Reviewed-by: Eric Blake Message-Id: <20210610100802.5888-18-vsementsov@virtuozzo.com> [eblake: comment tweaks] Signed-off-by: Eric Blake

nbd: make nbd_read* return -EIO on error

2021-02-03T14:17:12+00:00

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 Reviewed-by: Vladimir Sementsov-Ogievskiy Message-Id: <20210129073859.683063-4-rvkagan@yandex-team.ru> Signed-off-by: Eric Blake