linux.git/fs/dlm/midcomms.c, branch v5.14

fs: dlm: invalid buffer access in lookup error

2021-06-11T17:44:47+00:00

This patch will evaluate the message length if a dlm opts header can fit
in before accessing it if a node lookup fails. The invalid sequence
error means that the version detection failed and an unexpected message
arrived. For debugging such situation the type of arrived message is
important to know.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: fix race in mhandle deletion

2021-06-11T17:44:47+00:00

This patch fixes a race between mhandle deletion in case of receiving an
acknowledge and flush of all pending mhandle in cases of an timeout or
resetting node states.

Fixes: 489d8e559c65 ("fs: dlm: add reliable connection if reconnect")
Reported-by: Guillaume Nault 
Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: rename socket and app buffer defines

2021-06-02T16:53:04+00:00

This patch renames DEFAULT_BUFFER_SIZE to DLM_MAX_SOCKET_BUFSIZE and
LOWCOMMS_MAX_TX_BUFFER_LEN to DLM_MAX_APP_BUFSIZE as they are proper
names to define what's behind those values. The DLM_MAX_SOCKET_BUFSIZE
defines the maximum size of buffer which can be handled on socket layer,
the DLM_MAX_APP_BUFSIZE defines the maximum size of buffer which can be
handled by the DLM application layer.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: Fix spelling mistake "stucked" -> "stuck"

2021-05-26T14:49:04+00:00

There are spelling mistake in log messages. Fix these.

Signed-off-by: Colin Ian King 
Signed-off-by: David Teigland

fs: dlm: add midcomms debugfs functionality

2021-05-25T14:22:20+00:00

This patch adds functionality to debug midcomms per connection state
inside a comms directory which is similar like dlm configfs. Currently
there exists the possibility to read out two attributes which is the
send queue counter and the version of each midcomms node state.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: add reliable connection if reconnect

2021-05-25T14:22:20+00:00

This patch introduce to make a tcp lowcomms connection reliable even if
reconnects occurs. This is done by an application layer re-transmission
handling and sequence numbers in dlm protocols. There are three new dlm
commands:

DLM_OPTS:

This will encapsulate an existing dlm message (and rcom message if they
don't have an own application side re-transmission handling). As optional
handling additional tlv's (type length fields) can be appended. This can
be for example a sequence number field. However because in DLM_OPTS the
lockspace field is unused and a sequence number is a mandatory field it
isn't made as a tlv and we put the sequence number inside the lockspace
id. The possibility to add optional options are still there for future
purposes.

DLM_ACK:

Just a dlm header to acknowledge the receive of a DLM_OPTS message to
it's sender.

DLM_FIN:

This provides a 4 way handshake for connection termination inclusive
support for half-closed connections. It's provided on application layer
because SCTP doesn't support half-closed sockets, the shutdown() call
can interrupted by e.g. TCP resets itself and a hard logic to implement
it because the othercon paradigm in lowcomms. The 4-way termination
handshake also solve problems to synchronize peer EOF arrival and that
the cluster manager removes the peer in the node membership handling of
DLM. In some cases messages can be still transmitted in this time and we
need to wait for the node membership event.

To provide a reliable connection the node will retransmit all
unacknowledges message to it's peer on reconnect. The receiver will then
filtering out the next received message and drop all messages which are
duplicates.

As RCOM_STATUS and RCOM_NAMES messages are the first messages which are
exchanged and they have they own re-transmission handling, there exists
logic that these messages must be first. If these messages arrives we
store the dlm version field. This handling is on DLM 3.1 and after this
patch 3.2 the same. A backwards compatibility handling has been added
which seems to work on tests without tcpkill, however it's not recommended
to use DLM 3.1 and 3.2 at the same time, because DLM 3.2 tries to fix long
term bugs in the DLM protocol.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: make buffer handling per msg

2021-05-25T14:22:20+00:00

This patch makes the void pointer handle for lowcomms functionality per
message and not per page allocation entry. A refcount handling for the
handle was added to keep the message alive until the user doesn't need
it anymore.

There exists now a per message callback which will be called when
allocating a new buffer. This callback will be guaranteed to be called
according the order of the sending buffer, which can be used that the
caller increments a sequence number for the dlm message handle.

For transition process we cast the dlm_mhandle to dlm_msg and vice versa
until the midcomms layer will implement a specific dlm_mhandle structure.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: add more midcomms hooks

2021-05-25T14:22:20+00:00

This patch prepares hooks to redirect to the midcomms layer which will
be used by the midcomms re-transmit handling.

There exists the new concept of stateless buffers allocation and
commits. This can be used to bypass the midcomms re-transmit handling. It
is used by RCOM_STATUS and RCOM_NAMES messages, because they have their
own ping-like re-transmit handling. As well these two messages will be
used to determine the DLM version per node, because these two messages
are per observation the first messages which are exchanged.

Cluster manager events for node membership are added to add support for
half-closed connections in cases that the peer connection get to
an end of file but DLM still holds membership of the node. In
this time DLM can still trigger new message which we should allow. After
the cluster manager node removal event occurs it safe to close the
connection.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: remove unaligned memory access handling

2021-03-09T14:56:42+00:00

This patch removes unaligned memory access handling for receiving
midcomms messages. This handling will not fix the unaligned memory
access in general. All messages should be length aligned to 8 bytes,
there exists cases where this isn't the case. It's part of the sending
handling to not send such messages. As the sending handling itself, with
the internal allocator of page buffers, can occur in unaligned memory
access of dlm message fields we just ignore that problem for now as it
seems this code is used by architecture which can handle it.

This patch adds a comment to take care about that problem in a major
bump of dlm protocol.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland

fs: dlm: check on minimum msglen size

2021-03-09T14:56:42+00:00

This patch adds an additional check for minimum dlm header size which is
an invalid dlm message and signals a broken stream. A msglen field cannot
be less than the dlm header size because the field is inclusive header
lengths.

Signed-off-by: Alexander Aring 
Signed-off-by: David Teigland