dlm: use kernel_connect() and kernel_bind()

commit e9cdebbe23f1aa9a1caea169862f479ab3fa2773 upstream.

Recent changes to kernel_connect() and kernel_bind() ensure that
callers are insulated from cha

dlm: use kernel_connect() and kernel_bind()

commit e9cdebbe23f1aa9a1caea169862f479ab3fa2773 upstream.

Recent changes to kernel_connect() and kernel_bind() ensure that
callers are insulated from changes to the address parameter made by BPF
SOCK_ADDR hooks. This patch wraps direct calls to ops->connect() and
ops->bind() with kernel_connect() and kernel_bind() to protect callers
in such cases.

Link: https://lore.kernel.org/netdev/9944248dba1bce861375fcce9de663934d933ba9.camel@redhat.com/
Fixes: d74bad4e74ee ("bpf: Hooks for sys_connect")
Fixes: 4fbac77d2d09 ("bpf: Hooks for sys_bind")
Cc: stable@vger.kernel.org
Signed-off-by: Jordan Rife <jrife@google.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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fs: dlm: remove unused processed_nodes

The variable processed_nodes is not being used by commit 1696c75f1864
("fs: dlm: add send ack threshold and append acks to msgs"). This patch
removes the lefto

fs: dlm: remove unused processed_nodes

The variable processed_nodes is not being used by commit 1696c75f1864
("fs: dlm: add send ack threshold and append acks to msgs"). This patch
removes the leftover of this commit.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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dlm: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage

When transmitting data, call down a layer using a single sendmsg with
MSG_SPLICE_PAGES to indicate that content should be spliced rather using

dlm: Use sendmsg(MSG_SPLICE_PAGES) rather than sendpage

When transmitting data, call down a layer using a single sendmsg with
MSG_SPLICE_PAGES to indicate that content should be spliced rather using
sendpage. This allows ->sendpage() to be replaced by something that can
handle multiple multipage folios in a single transaction.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Christine Caulfield <ccaulfie@redhat.com>
cc: David Teigland <teigland@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: cluster-devel@redhat.com
Link: https://lore.kernel.org/r/20230623225513.2732256-7-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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fs: dlm: add send ack threshold and append acks to msgs

This patch changes the time when we sending an ack back to tell the
other side it can free some message because it is arrived on the
receiver

fs: dlm: add send ack threshold and append acks to msgs

This patch changes the time when we sending an ack back to tell the
other side it can free some message because it is arrived on the
receiver node, due random reconnects e.g. TCP resets this is handled as
well on application layer to not let DLM run into a deadlock state.

The current handling has the following problems:

1. We end in situations that we only send an ack back message of 16
bytes out and no other messages. Whereas DLM has logic to combine
so much messages as it can in one send() socket call. This behaviour
can be discovered by "trace-cmd start -e dlm_recv" and observing the
ret field being 16 bytes.

2. When processing of DLM messages will never end because we receive a
lot of messages, we will not send an ack back as it happens when
the processing loop ends.

This patch introduces a likely and unlikely threshold case. The likely
case will send an ack back on a transmit path if the threshold is
triggered of amount of processed upper layer protocol. This will solve
issue 1 because it will be send when another normal DLM message will be
sent. It solves issue 2 because it is not part of the processing loop.

There is however a unlikely case, the unlikely case has a bigger
threshold and will be triggered when we only receive messages and do not
sent any message back. This case avoids that the sending node will keep
a lot of message for a long time as we send sometimes ack backs to tell
the sender to finally release messages.

The atomic cmpxchg() is there to provide a atomically ack send with
reset of the upper layer protocol delivery counter.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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fs: dlm: filter ourself midcomms calls

It makes no sense to call midcomms/lowcomms functionality for the local
node as socket functionality is only required for remote nodes. This
patch filters thos

fs: dlm: filter ourself midcomms calls

It makes no sense to call midcomms/lowcomms functionality for the local
node as socket functionality is only required for remote nodes. This
patch filters those calls in the upper layer of lockspace membership
handling instead of doing it in midcomms/lowcomms layer as they should
never be aware of local nodeid.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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fs: dlm: cleanup STOP_IO bitflag set when stop io

There should no difference between setting the CF_IO_STOP flag
before restore_callbacks() to do it before or afterwards. The
restore_callbacks() wil

fs: dlm: cleanup STOP_IO bitflag set when stop io

There should no difference between setting the CF_IO_STOP flag
before restore_callbacks() to do it before or afterwards. The
restore_callbacks() will be sure that no callback is executed anymore
when the bit wasn't set.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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fs: dlm: don't check othercon twice

This patch removes an another check if con->othercon set inside the
branch which already does that.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-o

fs: dlm: don't check othercon twice

This patch removes an another check if con->othercon set inside the
branch which already does that.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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fs: dlm: fix missing pending to false

This patch sets the process_dlm_messages_pending boolean to false when
there was no message to process. It is a case which should not happen
but if we are prepa

fs: dlm: fix missing pending to false

This patch sets the process_dlm_messages_pending boolean to false when
there was no message to process. It is a case which should not happen
but if we are prepared to recover from this situation by setting pending
boolean to false.

Cc: stable@vger.kernel.org
Fixes: dbb751ffab0b ("fs: dlm: parallelize lowcomms socket handling")
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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net: annotate lockless accesses to sk->sk_err_soft

This field can be read/written without lock synchronization.

tcp and dccp have been handled in different patches.

Signed-off-by: Eric Dumazet <ed

net: annotate lockless accesses to sk->sk_err_soft

This field can be read/written without lock synchronization.

tcp and dccp have been handled in different patches.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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DLM: increase socket backlog to avoid hangs with 16 nodes

On a 16 node virtual cluster with e1000 NICs joining the 12th node prints
SYN flood warnings for the DLM port:
Dec 21 01:46:41 localhost ker

DLM: increase socket backlog to avoid hangs with 16 nodes

On a 16 node virtual cluster with e1000 NICs joining the 12th node prints
SYN flood warnings for the DLM port:
Dec 21 01:46:41 localhost kernel: [ 2146.516664] TCP: request_sock_TCP: Possible SYN flooding on port 21064. Sending cookies. Check SNMP counters.

And then joining a DLM lockspace hangs:
```
Dec 21 01:49:00 localhost kernel: [ 2285.780913] INFO: task xapi-clusterd:17638 blocked for more than 120 seconds.
Dec 21 01:49:00 localhost kernel: [ 2285.786476] Not tainted 4.4.0+10 #1
Dec 21 01:49:00 localhost kernel: [ 2285.789043] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Dec 21 01:49:00 localhost kernel: [ 2285.794611] xapi-clusterd D ffff88001930bc58 0 17638 1 0x00000000
Dec 21 01:49:00 localhost kernel: [ 2285.794615] ffff88001930bc58 ffff880025593800 ffff880022433800 ffff88001930c000
Dec 21 01:49:00 localhost kernel: [ 2285.794617] ffff88000ef4a660 ffff88000ef4a658 ffff880022433800 ffff88000ef4a000
Dec 21 01:49:00 localhost kernel: [ 2285.794619] ffff88001930bc70 ffffffff8159f6b4 7fffffffffffffff ffff88001930bd10
Dec 21 01:49:00 localhost kernel: [ 2285.794644] [<ffffffff811570fe>] ? printk+0x4d/0x4f
Dec 21 01:49:00 localhost kernel: [ 2285.794647] [<ffffffff810b1741>] ? __raw_callee_save___pv_queued_spin_unlock+0x11/0x20
Dec 21 01:49:00 localhost kernel: [ 2285.794649] [<ffffffff815a085d>] wait_for_completion+0x9d/0x110
Dec 21 01:49:00 localhost kernel: [ 2285.794653] [<ffffffff810979e0>] ? wake_up_q+0x80/0x80
Dec 21 01:49:00 localhost kernel: [ 2285.794661] [<ffffffffa03fa4b8>] dlm_new_lockspace+0x908/0xac0 [dlm]
Dec 21 01:49:00 localhost kernel: [ 2285.794665] [<ffffffff810aaa60>] ? prepare_to_wait_event+0x100/0x100
Dec 21 01:49:00 localhost kernel: [ 2285.794670] [<ffffffffa0402e37>] device_write+0x497/0x6b0 [dlm]
Dec 21 01:49:00 localhost kernel: [ 2285.794673] [<ffffffff811834f0>] ? handle_mm_fault+0x7f0/0x13b0
Dec 21 01:49:00 localhost kernel: [ 2285.794677] [<ffffffff811b4438>] __vfs_write+0x28/0xd0
Dec 21 01:49:00 localhost kernel: [ 2285.794679] [<ffffffff811b4b7f>] ? rw_verify_area+0x6f/0xd0
Dec 21 01:49:00 localhost kernel: [ 2285.794681] [<ffffffff811b4dc1>] vfs_write+0xb1/0x190
Dec 21 01:49:00 localhost kernel: [ 2285.794686] [<ffffffff8105ffc2>] ? __do_page_fault+0x302/0x420
Dec 21 01:49:00 localhost kernel: [ 2285.794688] [<ffffffff811b5986>] SyS_write+0x46/0xa0
Dec 21 01:49:00 localhost kernel: [ 2285.794690] [<ffffffff815a31ae>] entry_SYSCALL_64_fastpath+0x12/0x71
```

The previous limit of 5 seems like an arbitrary number, that doesn't match any
known DLM cluster size upper bound limit.

Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Cc: Christine Caulfield <ccaulfie@redhat.com>
Cc: David Teigland <teigland@redhat.com>
Cc: cluster-devel@redhat.com
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

show more ...

fs: dlm: add unbound flag to dlm_io workqueue

This patch will add the WQ_UNBOUND flag to the lowcomms dlm_io workqueue
which handles socket io handling to send and receive dlm messages.
The amount o

fs: dlm: add unbound flag to dlm_io workqueue

This patch will add the WQ_UNBOUND flag to the lowcomms dlm_io workqueue
which handles socket io handling to send and receive dlm messages.
The amount of sockets will be 2 for a 3 node cluster. Each socket has
two different workers for doing send and receive work by calling socket
API functionality. Each worker will do their task in order to send dlm
messages in a ordered stream based socket communication. On receive
side the receive buffer will be queued up for an ordered dlm_process
workqueue to parse received dlm messages. The parsing need to be done
currently in an ordered synchronized way because the dlm message processing
is not being made to parse parallel.

After explaining all those workqueue behaviours in lowcomms, the dlm_io
workqueue is only being used for socket handling. Each socket handling
has 2 workers (send and receive). In a 3 cluster node we will end up
with 4 workers. Without the WQ_UNBOUND flag the workers are tight to a
CPU and can never switch, this could be an advantage because local CPU
execution. However with dlm_locktorture testcase I expierenced not all
workers are always in use and my assumption is that some workers are
bound to the same CPU. We should always send or receive when we are
ready to do so, one reason why we disable nigel algorithm on sockets.
We should be safe to do the socket io handling on any CPU which can be
switched during runtime. There is no assumption that the worker stays on
the same CPU. There is no need to respect any workqueue concurrency
model that each worker can only run on one CPU. Lowcomms queue_work()
mechanism has an higher level flag to be sure that it can't schedule
work if the previous worker did not signal it to keep ordered socket
handling. Therefore this patch sets the WQ_UNBOUND flag to allow workers
being executed by any available CPU.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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fs: dlm: bring back previous shutdown handling

This patch mostly reverts commit 4f567acb0b86 ("fs: dlm: remove socket
shutdown handling"). There can be situations where the dlm midcomms nodes
hash a

fs: dlm: bring back previous shutdown handling

This patch mostly reverts commit 4f567acb0b86 ("fs: dlm: remove socket
shutdown handling"). There can be situations where the dlm midcomms nodes
hash and lowcomms connection hash are not equal, but we need to guarantee
that the lowcomms are all closed on a last release of a dlm lockspace,
when a shutdown is invoked. This patch guarantees that we always close
all sockets managed by the lowcomms connection hash, and calls shutdown
for the last message sent. This ensures we don't cut the socket, which
could cause the peer to get a connection reset.

In future we should try to merge the midcomms/lowcomms hashes into one
hash and not handle both in separate hashes.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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net/sock: Introduce trace_sk_data_ready()

As suggested by Cong, introduce a tracepoint for all ->sk_data_ready()
callback implementations. For example:

<...>
iperf-609 [002] ..... 70.660425: s

net/sock: Introduce trace_sk_data_ready()

As suggested by Cong, introduce a tracepoint for all ->sk_data_ready()
callback implementations. For example:

<...>
iperf-609 [002] ..... 70.660425: sk_data_ready: family=2 protocol=6 func=sock_def_readable
iperf-609 [002] ..... 70.660436: sk_data_ready: family=2 protocol=6 func=sock_def_readable
<...>

Suggested-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Peilin Ye <peilin.ye@bytedance.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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Treewide: Stop corrupting socket's task_frag

Since moving to memalloc_nofs_save/restore, SUNRPC has stopped setting the
GFP_NOIO flag on sk_allocation which the networking system uses to decide
when

Treewide: Stop corrupting socket's task_frag

Since moving to memalloc_nofs_save/restore, SUNRPC has stopped setting the
GFP_NOIO flag on sk_allocation which the networking system uses to decide
when it is safe to use current->task_frag. The results of this are
unexpected corruption in task_frag when SUNRPC is involved in memory
reclaim.

The corruption can be seen in crashes, but the root cause is often
difficult to ascertain as a crashing machine's stack trace will have no
evidence of being near NFS or SUNRPC code. I believe this problem to
be much more pervasive than reports to the community may indicate.

Fix this by having kernel users of sockets that may corrupt task_frag due
to reclaim set sk_use_task_frag = false. Preemptively correcting this
situation for users that still set sk_allocation allows them to convert to
memalloc_nofs_save/restore without the same unexpected corruptions that are
sure to follow, unlikely to show up in testing, and difficult to bisect.

CC: Philipp Reisner <philipp.reisner@linbit.com>
CC: Lars Ellenberg <lars.ellenberg@linbit.com>
CC: "Christoph Böhmwalder" <christoph.boehmwalder@linbit.com>
CC: Jens Axboe <axboe@kernel.dk>
CC: Josef Bacik <josef@toxicpanda.com>
CC: Keith Busch <kbusch@kernel.org>
CC: Christoph Hellwig <hch@lst.de>
CC: Sagi Grimberg <sagi@grimberg.me>
CC: Lee Duncan <lduncan@suse.com>
CC: Chris Leech <cleech@redhat.com>
CC: Mike Christie <michael.christie@oracle.com>
CC: "James E.J. Bottomley" <jejb@linux.ibm.com>
CC: "Martin K. Petersen" <martin.petersen@oracle.com>
CC: Valentina Manea <valentina.manea.m@gmail.com>
CC: Shuah Khan <shuah@kernel.org>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: David Howells <dhowells@redhat.com>
CC: Marc Dionne <marc.dionne@auristor.com>
CC: Steve French <sfrench@samba.org>
CC: Christine Caulfield <ccaulfie@redhat.com>
CC: David Teigland <teigland@redhat.com>
CC: Mark Fasheh <mark@fasheh.com>
CC: Joel Becker <jlbec@evilplan.org>
CC: Joseph Qi <joseph.qi@linux.alibaba.com>
CC: Eric Van Hensbergen <ericvh@gmail.com>
CC: Latchesar Ionkov <lucho@ionkov.net>
CC: Dominique Martinet <asmadeus@codewreck.org>
CC: Ilya Dryomov <idryomov@gmail.com>
CC: Xiubo Li <xiubli@redhat.com>
CC: Chuck Lever <chuck.lever@oracle.com>
CC: Jeff Layton <jlayton@kernel.org>
CC: Trond Myklebust <trond.myklebust@hammerspace.com>
CC: Anna Schumaker <anna@kernel.org>
CC: Steffen Klassert <steffen.klassert@secunet.com>
CC: Herbert Xu <herbert@gondor.apana.org.au>

Suggested-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Reviewed-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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fs: dlm: fix building without lockdep

This patch uses assert_spin_locked() instead of lockdep_is_held()
where it's available to use because lockdep_is_held() is only available
if CONFIG_LOCKDEP is s

fs: dlm: fix building without lockdep

This patch uses assert_spin_locked() instead of lockdep_is_held()
where it's available to use because lockdep_is_held() is only available
if CONFIG_LOCKDEP is set.

In other cases like lockdep_sock_is_held() we surround it by a
CONFIG_LOCKDEP idef.

Fixes: dbb751ffab0b ("fs: dlm: parallelize lowcomms socket handling")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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fs: dlm: parallelize lowcomms socket handling

This patch is rework of lowcomms handling, the main goal was here to
handle recvmsg() and sendpage() to run parallel. Parallel in two senses:
1. per con

fs: dlm: parallelize lowcomms socket handling

This patch is rework of lowcomms handling, the main goal was here to
handle recvmsg() and sendpage() to run parallel. Parallel in two senses:
1. per connection and 2. that recvmsg()/sendpage() doesn't block each
other.

Currently recvmsg()/sendpage() cannot run parallel because two
workqueues "dlm_recv" and "dlm_send" are ordered workqueues. That means
only one work item can be executed. The amount of queue items will be
increased about the amount of nodes being inside the cluster. The current
two workqueues for sending and receiving can also block each other if the
same connection is executed at the same time in dlm_recv and dlm_send
workqueue because a per connection mutex for the socket handling.

To make it more parallel we introduce one "dlm_io" workqueue which is
not an ordered workqueue, the amount of workers are not limited. Due
per connection flags SEND/RECV pending we schedule workers ordered per
connection and per send and receive task. To get rid of the mutex
blocking same workers to do socket handling we switched to a semaphore
which handles socket operations as read lock and sock releases as write
operations, to prevent sock_release() being called while the socket is
being used.

There might be more optimization removing the semaphore and replacing it
with other synchronization mechanism, however due other circumstances
e.g. othercon behaviour it seems complicated to doing this change. I
added comments to remove the othercon handling and moving to a different
synchronization mechanism as this is done. We need to do that to the next
dlm major version upgrade because it is not backwards compatible with the
current connect mechanism.

The processing of dlm messages need to be still handled by a ordered
workqueue. An dlm_process ordered workqueue was introduced which gets
filled by the receive worker. This is probably the next bottleneck of
DLM but the application can't currently parse dlm messages parallel. A
comment was introduced to lift the workqueue context of dlm processing
in a non-sleepable softirq to get messages processing done fast.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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fs: dlm: don't init error value

This patch removes a init of an error value to -EINVAL which is not
necessary.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <te

fs: dlm: don't init error value

This patch removes a init of an error value to -EINVAL which is not
necessary.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

show more ...

fs: dlm: use saved sk_error_report()

This patch changes the handling of calling the original
sk_error_report() by not putting it on the stack and calling it later.
If the listen_sock.sk_error_report

fs: dlm: use saved sk_error_report()

This patch changes the handling of calling the original
sk_error_report() by not putting it on the stack and calling it later.
If the listen_sock.sk_error_report() is NULL in this moment it indicates
a bug in our implementation.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

show more ...

fs: dlm: use sock2con without checking null

This patch removes null checks on private data for sockets. If we have a
null dereference there we having a bug in our implementation that such
callback o

fs: dlm: use sock2con without checking null

This patch removes null checks on private data for sockets. If we have a
null dereference there we having a bug in our implementation that such
callback occurs in this state.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

show more ...

fs: dlm: remove dlm_node_addrs lookup list

This patch merges the dlm_node_addrs lookup list to the connection
structure. It is a per node mapping to some configuration setup by
configfs. We don't ne

fs: dlm: remove dlm_node_addrs lookup list

This patch merges the dlm_node_addrs lookup list to the connection
structure. It is a per node mapping to some configuration setup by
configfs. We don't need two lookup structures. The connection hash has
now a lifetime like the dlm_node_addrs entries. Means we add only new
entries when configure cluster and not while new connections are coming
in, remove connection when a node got fenced and cleanup all connection
when the dlm exits. It should work the same and even will show more
issues because we don't try to somehow keep those two data structures in
sync with the current cluster configuration.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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fs: dlm: don't put dlm_local_addrs on heap

This patch removes to allocate the dlm_local_addr[] pointers on the
heap. Instead we directly store the type of "struct sockaddr_storage".
This removes fun

fs: dlm: don't put dlm_local_addrs on heap

This patch removes to allocate the dlm_local_addr[] pointers on the
heap. Instead we directly store the type of "struct sockaddr_storage".
This removes function deinit_local() because it was freeing memory only.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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fs: dlm: cleanup listen sock handling

This patch removes save_listen_callbacks() and add_listen_sock() as they
are only used once in lowcomms functionality. For shutdown lowcomms it's
not necessary

fs: dlm: cleanup listen sock handling

This patch removes save_listen_callbacks() and add_listen_sock() as they
are only used once in lowcomms functionality. For shutdown lowcomms it's
not necessary to whole flush the workqueues to synchronize with
restoring the old sk_data_ready() callback. Only the listen con receive
work need to be cancelled. For each individual node shutdown we should be
sure that last ack was been transmitted which is done by flushing per
connection swork worker.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

show more ...

fs: dlm: remove socket shutdown handling

Since commit 489d8e559c65 ("fs: dlm: add reliable connection if
reconnect") we have functionality like TCP offers for half-closed
sockets on dlm application

fs: dlm: remove socket shutdown handling

Since commit 489d8e559c65 ("fs: dlm: add reliable connection if
reconnect") we have functionality like TCP offers for half-closed
sockets on dlm application protocol layer. This feature is required
because the cluster manager events about leaving resource memberships
can be locally already occurred but other cluster nodes having a pending
leaving membership over the cluster manager protocol happening. In this
time the local dlm node already shutdown it's connection and don't
transmit anymore any new dlm messages, but however it still needs to be
able to accept dlm messages because the pending leave membership request
of the cluster manager protocol which the dlm kernel implementation has
no control about it.

We have this functionality on the application for two reasons, the main
reason is that SCTP does not support such functionality on socket
layer. But we can do it inside application layer.

Another small issue is that this feature is broken in the TCP world
because some NAT devices does not implement such functionality
correctly. This is the same reason why the reliable connection session
layer in DLM exists. We give up on middle devices in the networking
which sends e.g. TCP resets out. In DLM we cannot have any message
dropping and we ensure it over a session layer that it can't happen.

Back to the half-closed grace shutdown handling. It's not necessary
anymore to do it on socket layer (which is only support for TCP sockets)
because we do it on application layer. This patch removes this handling,
if there are still issues then we have a problem on the application
layer for such handling.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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fs: dlm: use listen sock as dlm running indicator

This patch will switch from dlm_allow_conn to check if dlm lowcomms is
running or not to if we actually have a listen socket set or not. The
list so

fs: dlm: use listen sock as dlm running indicator

This patch will switch from dlm_allow_conn to check if dlm lowcomms is
running or not to if we actually have a listen socket set or not. The
list socket will be set and unset in lowcomms start and shutdown
functionality. To synchronize with data_ready() callback we will set the
socket callback to NULL while socket lock is held.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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fs: dlm: use list_first_entry_or_null

Instead of check on list_empty() we can do the same with
list_first_entry_or_null() and return NULL if the returned value is NULL.

Signed-off-by: Alexander Ari

fs: dlm: use list_first_entry_or_null

Instead of check on list_empty() we can do the same with
list_first_entry_or_null() and return NULL if the returned value is NULL.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

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