[Cluster-devel] [PATCHv4 dlm/next 00/20] fs: dlm: introduce dlm re-transmission layer

[Cluster-devel] [PATCHv4 dlm/next 00/20] fs: dlm: introduce dlm re-transmission layer

[Alexander Aring]

Hi,

this is the final patch-series to make dlm reliable when re-connection
occurs. You can easily generate a couple of re-connections by running:

tcpkill -9 -i $IFACE port 21064

on your own to test these patches. At some time dlm will detect message
drops and will re-transmit messages if necessary. It introduces a new dlm
protocol behaviour and increases the dlm protocol version. I tested it
with SCTP as well and tried to be backwards compatible with dlm protocol
version 3.1. However I don't recommend at all to mix these versions
in a setup since dlm version 3.2 fixes long-term issues.

- Alex

changes since v4:
 - add big midcomms file header comment about what's the idea about
   midcomms layer and how it works.
 - add the close mutex lock to prevent running close API call while
   connection is being terimanted. However when a close call occurs
   it will terminate the current termination wait until the close
   lock is released. If the node is removed from the nodes hash the
   lowcomms close call will occur anyway.
   
   I added a define to insert some sleep to test this behaviour.

changes since v3:
 - make dlm messages to 8 byte boundary size (more pads), because there
   exists uint64_t fields and we should prepared for future 8 byte fields.
   This will make it directly aligned to 4 and 2 as well.
 - change unaligned memory access handling. I will not fix it yet. It
   seems nobody is using dlm on an architecture which cannot handle
   unaligned memory access at all (panics). However I added a note that
   this is a known problem. There is a slightly performance improvement
   (depends on many things e.g. if another message gets allocated after a
   (len % 8) != 0 message length got allocated). However I saw that such
   cases are rarely (for now some user space messages only) occur.

   The receiving side is not the problem here, the sending side is it
   and we run in a unaligned memory access in dlm messages fields there
   as well. However, fixing sending side will fix the receiving side and
   more length checks can be applied then to drop invalid message
   lengths.
 - be sure to remove node from hash at first at close call

   I am a little bit worried about the midcomms/lowcomms close call and
   the timer is running at exactly this time and maybe begins to
   re-transmit messages. I thought about to stop/start the timer but now
   I ended up to remove the node from the hash at first and be sure that
   no readers are left when calling lowcomms close. I think this should
   be fine because we "should" not receive any dlm messages from this
   node while close is running.

 - add patch "fs: dlm: add per node receive flush"

   As I was worried about that the lowcomms close call flushes the receive
   work on a socket close and we already removed the node from the hash,
   I added a functionality to flush the receive work right before we remove
   the node. With this functionality we male sure we don't receive any
   messages after we removed the node from the hash.
 - add patch "fs: dlm: remove obsolete code and comment"
 - add patch "fs: dlm: check for invalid namelen"

changes since v2:
 - add patch "fs: dlm: set connected bit after accept"
 - add patch "fs: dlm: set subclass for othercon sock_mutex"
 - change title "fs: dlm: public utils header utils" to
   "fs: dlm: public header in out utility"
 - squash "fs: dlm: add check for minimum allocation length" into
   "fs: dlm: remove unaligned memory access handling"
 - make the midcomms timeout a little bit longer, because I saw
   sometimes it's not enough (I hope that was the reason)
 - midcomms: fix version mismatch handling
 - remove DLM_ACK in invalid sequence handling
 - add additional length check in dlm_opts_check_msglen()
 - use optlen to skip DLM_OPTS header
 - add DLM_MSGLEN_IS_NOT_ALIGNED to check if msglen is proper
   aligned before parsing
 - change dlm_midcomms_close() to close first then cut queues,
   because lowcomms close will may flush some messages which
   need to be dropped afterwards if seq doesn't fit.
 - remove newline in "fs: dlm: add more midcomms hooks"
 - may more changes which I don't have on track.
 - change defines handling for calculating max application buffer
   size vs max allocation size
 - run aspell on my commit msgs

Alexander Aring (20):
  fs: dlm: set connected bit after accept
  fs: dlm: set subclass for othercon sock_mutex
  fs: dlm: add errno handling to check callback
  fs: dlm: add check if dlm is currently running
  fs: dlm: change allocation limits
  fs: dlm: public header in out utility
  fs: dlm: use GFP_ZERO for page buffer
  fs: dlm: simplify writequeue handling
  fs: dlm: add more midcomms hooks
  fs: dlm: make buffer handling per msg
  fs: dlm: make new buffer handling softirq ready
  fs: dlm: add functionality to re-transmit a message
  fs: dlm: move out some hash functionality
  fs: dlm: remove unaligned memory access handling
  fs: dlm: add union in dlm header for lockspace id
  fs: dlm: add per node receive flush
  fs: dlm: add reliable connection if reconnect
  fs: dlm: don't allow half transmitted messages
  fs: dlm: remove obsolete code and comment
  fs: dlm: check for invalid namelen

 fs/dlm/config.c       |   60 +-
 fs/dlm/dlm_internal.h |   41 +-
 fs/dlm/lock.c         |   16 +-
 fs/dlm/lockspace.c    |    5 +-
 fs/dlm/lowcomms.c     |  288 +++++++---
 fs/dlm/lowcomms.h     |   27 +-
 fs/dlm/member.c       |   16 +
 fs/dlm/member.h       |    1 +
 fs/dlm/midcomms.c     | 1266 +++++++++++++++++++++++++++++++++++++++--
 fs/dlm/midcomms.h     |   10 +
 fs/dlm/rcom.c         |   61 +-
 fs/dlm/recoverd.c     |    3 +
 fs/dlm/user.c         |    3 +
 fs/dlm/util.c         |   10 +-
 fs/dlm/util.h         |    2 +
 15 files changed, 1628 insertions(+), 181 deletions(-)

-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 01/20] fs: dlm: set connected bit after accept

[Alexander Aring]

This patch sets the CF_CONNECTED bit when dlm accepts a connection from
another node. If we don't set this bit, next time if the connection
socket gets writable it will assume an event that the connection is
successfully connected. However that is only the case when the
connection did a connect.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lowcomms.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 372c34ff8594..2fd1e4c13663 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -930,6 +930,7 @@ static int accept_from_sock(struct listen_connection *con)
 		addcon = newcon;
 	}
 
+	set_bit(CF_CONNECTED, &addcon->flags);
 	mutex_unlock(&newcon->sock_mutex);
 
 	/*
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 02/20] fs: dlm: set subclass for othercon sock_mutex

[Alexander Aring]

This patch sets the lockdep subclass for the othercon socket mutex. In
various places the connection socket mutex is held while locking the
othercon socket mutex. This patch will remove lockdep warnings when such
case occurs.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lowcomms.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 2fd1e4c13663..d772e1d4461d 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -911,13 +911,14 @@ static int accept_from_sock(struct listen_connection *con)
 				goto accept_err;
 			}
 
+			lockdep_set_subclass(&othercon->sock_mutex, 1);
 			newcon->othercon = othercon;
 		} else {
 			/* close other sock con if we have something new */
 			close_connection(othercon, false, true, false);
 		}
 
-		mutex_lock_nested(&othercon->sock_mutex, 1);
+		mutex_lock(&othercon->sock_mutex);
 		add_sock(newsock, othercon);
 		addcon = othercon;
 		mutex_unlock(&othercon->sock_mutex);
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 03/20] fs: dlm: add errno handling to check callback

[Alexander Aring]

This allows to return individual errno values for the config attribute
check callback instead of returning invalid argument only.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/config.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/fs/dlm/config.c b/fs/dlm/config.c
index 49c5f9407098..73e6643903af 100644
--- a/fs/dlm/config.c
+++ b/fs/dlm/config.c
@@ -125,7 +125,7 @@ static ssize_t cluster_cluster_name_store(struct config_item *item,
 CONFIGFS_ATTR(cluster_, cluster_name);
 
 static ssize_t cluster_set(struct dlm_cluster *cl, unsigned int *cl_field,
-			   int *info_field, bool (*check_cb)(unsigned int x),
+			   int *info_field, int (*check_cb)(unsigned int x),
 			   const char *buf, size_t len)
 {
 	unsigned int x;
@@ -137,8 +137,11 @@ static ssize_t cluster_set(struct dlm_cluster *cl, unsigned int *cl_field,
 	if (rc)
 		return rc;
 
-	if (check_cb && check_cb(x))
-		return -EINVAL;
+	if (check_cb) {
+		rc = check_cb(x);
+		if (rc)
+			return rc;
+	}
 
 	*cl_field = x;
 	*info_field = x;
@@ -161,14 +164,20 @@ static ssize_t cluster_##name##_show(struct config_item *item, char *buf)     \
 }                                                                             \
 CONFIGFS_ATTR(cluster_, name);
 
-static bool dlm_check_zero(unsigned int x)
+static int dlm_check_zero(unsigned int x)
 {
-	return !x;
+	if (!x)
+		return -EINVAL;
+
+	return 0;
 }
 
-static bool dlm_check_buffer_size(unsigned int x)
+static int dlm_check_buffer_size(unsigned int x)
 {
-	return (x < DEFAULT_BUFFER_SIZE);
+	if (x < DEFAULT_BUFFER_SIZE)
+		return -EINVAL;
+
+	return 0;
 }
 
 CLUSTER_ATTR(tcp_port, dlm_check_zero);
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 04/20] fs: dlm: add check if dlm is currently running

[Alexander Aring]

This patch adds checks for dlm config attributes regarding to protocol
parameters as it makes only sense to change them when dlm is not running.
It also adds a check for valid protocol specifiers and return invalid
argument if they are not supported.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/config.c   | 34 ++++++++++++++++++++++++++++++++--
 fs/dlm/lowcomms.c |  2 +-
 fs/dlm/lowcomms.h |  3 +++
 3 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/fs/dlm/config.c b/fs/dlm/config.c
index 73e6643903af..ab26cf135710 100644
--- a/fs/dlm/config.c
+++ b/fs/dlm/config.c
@@ -164,6 +164,36 @@ static ssize_t cluster_##name##_show(struct config_item *item, char *buf)     \
 }                                                                             \
 CONFIGFS_ATTR(cluster_, name);
 
+static int dlm_check_protocol_and_dlm_running(unsigned int x)
+{
+	switch (x) {
+	case 0:
+		/* TCP */
+		break;
+	case 1:
+		/* SCTP */
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (dlm_allow_conn)
+		return -EBUSY;
+
+	return 0;
+}
+
+static int dlm_check_zero_and_dlm_running(unsigned int x)
+{
+	if (!x)
+		return -EINVAL;
+
+	if (dlm_allow_conn)
+		return -EBUSY;
+
+	return 0;
+}
+
 static int dlm_check_zero(unsigned int x)
 {
 	if (!x)
@@ -180,7 +210,7 @@ static int dlm_check_buffer_size(unsigned int x)
 	return 0;
 }
 
-CLUSTER_ATTR(tcp_port, dlm_check_zero);
+CLUSTER_ATTR(tcp_port, dlm_check_zero_and_dlm_running);
 CLUSTER_ATTR(buffer_size, dlm_check_buffer_size);
 CLUSTER_ATTR(rsbtbl_size, dlm_check_zero);
 CLUSTER_ATTR(recover_timer, dlm_check_zero);
@@ -188,7 +218,7 @@ CLUSTER_ATTR(toss_secs, dlm_check_zero);
 CLUSTER_ATTR(scan_secs, dlm_check_zero);
 CLUSTER_ATTR(log_debug, NULL);
 CLUSTER_ATTR(log_info, NULL);
-CLUSTER_ATTR(protocol, NULL);
+CLUSTER_ATTR(protocol, dlm_check_protocol_and_dlm_running);
 CLUSTER_ATTR(mark, NULL);
 CLUSTER_ATTR(timewarn_cs, dlm_check_zero);
 CLUSTER_ATTR(waitwarn_us, NULL);
diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index d772e1d4461d..d25b9132c593 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -134,7 +134,7 @@ static DEFINE_SPINLOCK(dlm_node_addrs_spin);
 static struct listen_connection listen_con;
 static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
 static int dlm_local_count;
-static int dlm_allow_conn;
+int dlm_allow_conn;
 
 /* Work queues */
 static struct workqueue_struct *recv_workqueue;
diff --git a/fs/dlm/lowcomms.h b/fs/dlm/lowcomms.h
index 0918f9376489..f74888ed43b4 100644
--- a/fs/dlm/lowcomms.h
+++ b/fs/dlm/lowcomms.h
@@ -14,6 +14,9 @@
 
 #define LOWCOMMS_MAX_TX_BUFFER_LEN	4096
 
+/* switch to check if dlm is running */
+extern int dlm_allow_conn;
+
 int dlm_lowcomms_start(void);
 void dlm_lowcomms_stop(void);
 void dlm_lowcomms_exit(void);
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 05/20] fs: dlm: change allocation limits

[Alexander Aring]

While running tcpkill I experienced invalid header length values while
receiving to check that a node doesn't try to send a invalid dlm message
we also check on applications minimum allocation limit. Also use
DEFAULT_BUFFER_SIZE as maximum allocation limit. The define
LOWCOMMS_MAX_TX_BUFFER_LEN is to calculate maximum buffer limits on
application layer, future midcomms layer will subtract their needs from
this define.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lowcomms.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index d25b9132c593..2b468fbb2b43 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -1357,8 +1357,9 @@ void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
 	struct writequeue_entry *e;
 	int offset = 0;
 
-	if (len > LOWCOMMS_MAX_TX_BUFFER_LEN) {
-		BUILD_BUG_ON(PAGE_SIZE < LOWCOMMS_MAX_TX_BUFFER_LEN);
+	if (len > DEFAULT_BUFFER_SIZE ||
+	    len < sizeof(struct dlm_header)) {
+		BUILD_BUG_ON(PAGE_SIZE < DEFAULT_BUFFER_SIZE);
 		log_print("failed to allocate a buffer of size %d", len);
 		return NULL;
 	}
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 06/20] fs: dlm: public header in out utility

[Alexander Aring]

This patch allows to use header_out() and header_in() outside of dlm
util functionality.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/util.c | 4 ++--
 fs/dlm/util.h | 2 ++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/dlm/util.c b/fs/dlm/util.c
index cfd0d00b19ae..74a8c5bfe9b5 100644
--- a/fs/dlm/util.c
+++ b/fs/dlm/util.c
@@ -20,7 +20,7 @@
 #define DLM_ERRNO_ETIMEDOUT	       110
 #define DLM_ERRNO_EINPROGRESS	       115
 
-static void header_out(struct dlm_header *hd)
+void header_out(struct dlm_header *hd)
 {
 	hd->h_version		= cpu_to_le32(hd->h_version);
 	hd->h_lockspace		= cpu_to_le32(hd->h_lockspace);
@@ -28,7 +28,7 @@ static void header_out(struct dlm_header *hd)
 	hd->h_length		= cpu_to_le16(hd->h_length);
 }
 
-static void header_in(struct dlm_header *hd)
+void header_in(struct dlm_header *hd)
 {
 	hd->h_version		= le32_to_cpu(hd->h_version);
 	hd->h_lockspace		= le32_to_cpu(hd->h_lockspace);
diff --git a/fs/dlm/util.h b/fs/dlm/util.h
index cc719ca9397e..d46f23c7a6a0 100644
--- a/fs/dlm/util.h
+++ b/fs/dlm/util.h
@@ -15,6 +15,8 @@ void dlm_message_out(struct dlm_message *ms);
 void dlm_message_in(struct dlm_message *ms);
 void dlm_rcom_out(struct dlm_rcom *rc);
 void dlm_rcom_in(struct dlm_rcom *rc);
+void header_out(struct dlm_header *hd);
+void header_in(struct dlm_header *hd);
 
 #endif
 
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 07/20] fs: dlm: use GFP_ZERO for page buffer

[Alexander Aring]

This patch uses GFP_ZERO for allocate a page for the internal dlm
sending buffer allocator instead of calling memset zero after every
allocation. An already allocated space will never be reused again.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lock.c     | 2 --
 fs/dlm/lowcomms.c | 2 +-
 fs/dlm/rcom.c     | 2 --
 3 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 002123efc6b0..b93df39d0915 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -3541,8 +3541,6 @@ static int _create_message(struct dlm_ls *ls, int mb_len,
 	if (!mh)
 		return -ENOBUFS;
 
-	memset(mb, 0, mb_len);
-
 	ms = (struct dlm_message *) mb;
 
 	ms->m_header.h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 2b468fbb2b43..02ab939ad8d3 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -1336,7 +1336,7 @@ static struct writequeue_entry *new_writequeue_entry(struct connection *con,
 	if (!entry)
 		return NULL;
 
-	entry->page = alloc_page(allocation);
+	entry->page = alloc_page(allocation | __GFP_ZERO);
 	if (!entry->page) {
 		kfree(entry);
 		return NULL;
diff --git a/fs/dlm/rcom.c b/fs/dlm/rcom.c
index 73ddee5159d7..f5b1bd65728d 100644
--- a/fs/dlm/rcom.c
+++ b/fs/dlm/rcom.c
@@ -41,7 +41,6 @@ static int create_rcom(struct dlm_ls *ls, int to_nodeid, int type, int len,
 			  to_nodeid, type, len);
 		return -ENOBUFS;
 	}
-	memset(mb, 0, mb_len);
 
 	rc = (struct dlm_rcom *) mb;
 
@@ -462,7 +461,6 @@ int dlm_send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in)
 	mh = dlm_lowcomms_get_buffer(nodeid, mb_len, GFP_NOFS, &mb);
 	if (!mh)
 		return -ENOBUFS;
-	memset(mb, 0, mb_len);
 
 	rc = (struct dlm_rcom *) mb;
 
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 08/20] fs: dlm: simplify writequeue handling

[Alexander Aring]

This patch cleans up the current dlm sending allocator handling by using
some named macros, list functionality and removes some goto statements.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lowcomms.c | 83 ++++++++++++++++++++++++-----------------------
 1 file changed, 43 insertions(+), 40 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 02ab939ad8d3..8c826e95493c 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -102,6 +102,9 @@ struct listen_connection {
 	struct work_struct rwork;
 };
 
+#define DLM_WQ_REMAIN_BYTES(e) (PAGE_SIZE - e->end)
+#define DLM_WQ_LENGTH_BYTES(e) (e->end - e->offset)
+
 /* An entry waiting to be sent */
 struct writequeue_entry {
 	struct list_head list;
@@ -1332,7 +1335,7 @@ static struct writequeue_entry *new_writequeue_entry(struct connection *con,
 {
 	struct writequeue_entry *entry;
 
-	entry = kmalloc(sizeof(struct writequeue_entry), allocation);
+	entry = kzalloc(sizeof(*entry), allocation);
 	if (!entry)
 		return NULL;
 
@@ -1342,20 +1345,48 @@ static struct writequeue_entry *new_writequeue_entry(struct connection *con,
 		return NULL;
 	}
 
-	entry->offset = 0;
-	entry->len = 0;
-	entry->end = 0;
-	entry->users = 0;
 	entry->con = con;
+	entry->users = 1;
 
 	return entry;
 }
 
+static struct writequeue_entry *new_wq_entry(struct connection *con, int len,
+					     gfp_t allocation, char **ppc)
+{
+	struct writequeue_entry *e;
+
+	spin_lock(&con->writequeue_lock);
+	if (!list_empty(&con->writequeue)) {
+		e = list_last_entry(&con->writequeue, struct writequeue_entry, list);
+		if (DLM_WQ_REMAIN_BYTES(e) >= len) {
+			*ppc = page_address(e->page) + e->end;
+			e->end += len;
+			e->users++;
+			spin_unlock(&con->writequeue_lock);
+
+			return e;
+		}
+	}
+	spin_unlock(&con->writequeue_lock);
+
+	e = new_writequeue_entry(con, allocation);
+	if (!e)
+		return NULL;
+
+	*ppc = page_address(e->page);
+	e->end += len;
+
+	spin_lock(&con->writequeue_lock);
+	list_add_tail(&e->list, &con->writequeue);
+	spin_unlock(&con->writequeue_lock);
+
+	return e;
+};
+
 void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
 {
 	struct connection *con;
-	struct writequeue_entry *e;
-	int offset = 0;
 
 	if (len > DEFAULT_BUFFER_SIZE ||
 	    len < sizeof(struct dlm_header)) {
@@ -1368,35 +1399,7 @@ void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
 	if (!con)
 		return NULL;
 
-	spin_lock(&con->writequeue_lock);
-	e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
-	if ((&e->list == &con->writequeue) ||
-	    (PAGE_SIZE - e->end < len)) {
-		e = NULL;
-	} else {
-		offset = e->end;
-		e->end += len;
-		e->users++;
-	}
-	spin_unlock(&con->writequeue_lock);
-
-	if (e) {
-	got_one:
-		*ppc = page_address(e->page) + offset;
-		return e;
-	}
-
-	e = new_writequeue_entry(con, allocation);
-	if (e) {
-		spin_lock(&con->writequeue_lock);
-		offset = e->end;
-		e->end += len;
-		e->users++;
-		list_add_tail(&e->list, &con->writequeue);
-		spin_unlock(&con->writequeue_lock);
-		goto got_one;
-	}
-	return NULL;
+	return new_wq_entry(con, len, allocation, ppc);
 }
 
 void dlm_lowcomms_commit_buffer(void *mh)
@@ -1409,7 +1412,8 @@ void dlm_lowcomms_commit_buffer(void *mh)
 	users = --e->users;
 	if (users)
 		goto out;
-	e->len = e->end - e->offset;
+
+	e->len = DLM_WQ_LENGTH_BYTES(e);
 	spin_unlock(&con->writequeue_lock);
 
 	queue_work(send_workqueue, &con->swork);
@@ -1435,11 +1439,10 @@ static void send_to_sock(struct connection *con)
 
 	spin_lock(&con->writequeue_lock);
 	for (;;) {
-		e = list_entry(con->writequeue.next, struct writequeue_entry,
-			       list);
-		if ((struct list_head *) e == &con->writequeue)
+		if (list_empty(&con->writequeue))
 			break;
 
+		e = list_first_entry(&con->writequeue, struct writequeue_entry, list);
 		len = e->len;
 		offset = e->offset;
 		BUG_ON(len == 0 && e->users == 0);
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 09/20] fs: dlm: add more midcomms hooks

[Alexander Aring]

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.

The midcomms_remove_member() hook should be called when there is nothing
to send to the other node and the other node is still capable to
transmit dlm messages to the other node which called
midcomms_remove_member(). I experienced that the dlm protocol has a lack
of support for synchronize this event on protocol level. The result was
that there was still something to transmit but the other node was already
gone. This hook can be used to provide such synchronization. Although I
am not totally sure about the placement of this hook, I did not observed
issues yet when providing such synchronization on protocol layer.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/config.c    |  3 ++-
 fs/dlm/lock.c      |  6 ++---
 fs/dlm/lockspace.c |  5 +++--
 fs/dlm/member.c    | 16 ++++++++++++++
 fs/dlm/member.h    |  1 +
 fs/dlm/midcomms.c  | 44 +++++++++++++++++++++++++++++++++++++
 fs/dlm/midcomms.h  | 10 +++++++++
 fs/dlm/rcom.c      | 55 +++++++++++++++++++++++++++-------------------
 fs/dlm/recoverd.c  |  3 +++
 9 files changed, 115 insertions(+), 28 deletions(-)

diff --git a/fs/dlm/config.c b/fs/dlm/config.c
index ab26cf135710..ba8b1f104df3 100644
--- a/fs/dlm/config.c
+++ b/fs/dlm/config.c
@@ -20,6 +20,7 @@
 #include <net/sock.h>
 
 #include "config.h"
+#include "midcomms.h"
 #include "lowcomms.h"
 
 /*
@@ -532,7 +533,7 @@ static void drop_comm(struct config_group *g, struct config_item *i)
 	struct dlm_comm *cm = config_item_to_comm(i);
 	if (local_comm == cm)
 		local_comm = NULL;
-	dlm_lowcomms_close(cm->nodeid);
+	dlm_midcomms_close(cm->nodeid);
 	while (cm->addr_count--)
 		kfree(cm->addr[cm->addr_count]);
 	config_item_put(i);
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index b93df39d0915..b3fd823009f4 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -59,7 +59,7 @@
 #include "dlm_internal.h"
 #include <linux/dlm_device.h>
 #include "memory.h"
-#include "lowcomms.h"
+#include "midcomms.h"
 #include "requestqueue.h"
 #include "util.h"
 #include "dir.h"
@@ -3537,7 +3537,7 @@ static int _create_message(struct dlm_ls *ls, int mb_len,
 	   pass into lowcomms_commit and a message buffer (mb) that we
 	   write our data into */
 
-	mh = dlm_lowcomms_get_buffer(to_nodeid, mb_len, GFP_NOFS, &mb);
+	mh = dlm_midcomms_get_buffer(to_nodeid, mb_len, GFP_NOFS, &mb);
 	if (!mh)
 		return -ENOBUFS;
 
@@ -3589,7 +3589,7 @@ static int create_message(struct dlm_rsb *r, struct dlm_lkb *lkb,
 static int send_message(struct dlm_mhandle *mh, struct dlm_message *ms)
 {
 	dlm_message_out(ms);
-	dlm_lowcomms_commit_buffer(mh);
+	dlm_midcomms_commit_buffer(mh);
 	return 0;
 }
 
diff --git a/fs/dlm/lockspace.c b/fs/dlm/lockspace.c
index 561dcad08ad6..c9e0f5ac9f9a 100644
--- a/fs/dlm/lockspace.c
+++ b/fs/dlm/lockspace.c
@@ -16,6 +16,7 @@
 #include "member.h"
 #include "recoverd.h"
 #include "dir.h"
+#include "midcomms.h"
 #include "lowcomms.h"
 #include "config.h"
 #include "memory.h"
@@ -390,7 +391,7 @@ static int threads_start(void)
 	}
 
 	/* Thread for sending/receiving messages for all lockspace's */
-	error = dlm_lowcomms_start();
+	error = dlm_midcomms_start();
 	if (error) {
 		log_print("cannot start dlm lowcomms %d", error);
 		goto scand_fail;
@@ -407,7 +408,7 @@ static int threads_start(void)
 static void threads_stop(void)
 {
 	dlm_scand_stop();
-	dlm_lowcomms_stop();
+	dlm_midcomms_stop();
 }
 
 static int new_lockspace(const char *name, const char *cluster,
diff --git a/fs/dlm/member.c b/fs/dlm/member.c
index ceef3f2074ff..8291566766f3 100644
--- a/fs/dlm/member.c
+++ b/fs/dlm/member.c
@@ -15,6 +15,7 @@
 #include "recover.h"
 #include "rcom.h"
 #include "config.h"
+#include "midcomms.h"
 #include "lowcomms.h"
 
 int dlm_slots_version(struct dlm_header *h)
@@ -521,6 +522,20 @@ static struct dlm_config_node *find_config_node(struct dlm_recover *rv,
 	return NULL;
 }
 
+void dlm_flush_removed_members(struct dlm_ls *ls, struct dlm_recover *rv)
+{
+	const struct dlm_config_node *node;
+	const struct dlm_member *memb;
+
+	list_for_each_entry(memb, &ls->ls_nodes, list) {
+		node = find_config_node(rv, memb->nodeid);
+		if (node && !node->new)
+			continue;
+
+		midcomms_remove_member(memb->nodeid);
+	}
+}
+
 int dlm_recover_members(struct dlm_ls *ls, struct dlm_recover *rv, int *neg_out)
 {
 	struct dlm_member *memb, *safe;
@@ -563,6 +578,7 @@ int dlm_recover_members(struct dlm_ls *ls, struct dlm_recover *rv, int *neg_out)
 		if (dlm_is_member(ls, node->nodeid))
 			continue;
 		dlm_add_member(ls, node);
+		midcomms_add_member(node->nodeid);
 		log_rinfo(ls, "add member %d", node->nodeid);
 	}
 
diff --git a/fs/dlm/member.h b/fs/dlm/member.h
index 433b2fac9f4a..3a6dd2324283 100644
--- a/fs/dlm/member.h
+++ b/fs/dlm/member.h
@@ -26,6 +26,7 @@ int dlm_slots_copy_in(struct dlm_ls *ls);
 int dlm_slots_assign(struct dlm_ls *ls, int *num_slots, int *slots_size,
 		     struct dlm_slot **slots_out, uint32_t *gen_out);
 void dlm_lsop_recover_done(struct dlm_ls *ls);
+void dlm_flush_removed_members(struct dlm_ls *ls, struct dlm_recover *rv);
 
 #endif                          /* __MEMBER_DOT_H__ */
 
diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index fde3a6afe4be..717a3ed34f6a 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -30,6 +30,50 @@
 #include "lock.h"
 #include "midcomms.h"
 
+void *dlm_midcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
+{
+	return dlm_lowcomms_get_buffer(nodeid, len, allocation, ppc);
+}
+
+void dlm_midcomms_commit_buffer(void *mh)
+{
+	dlm_lowcomms_commit_buffer(mh);
+}
+
+void *dlm_midcomms_stateless_get_buffer(int nodeid, int len, gfp_t allocation,
+					char **ppc)
+{
+	return dlm_lowcomms_get_buffer(nodeid, len, allocation, ppc);
+}
+
+void dlm_midcomms_stateless_commit_buffer(void *mh)
+{
+	dlm_lowcomms_commit_buffer(mh);
+}
+
+void midcomms_add_member(int nodeid)
+{
+}
+
+void midcomms_remove_member(int nodeid)
+{
+}
+
+int dlm_midcomms_close(int nodeid)
+{
+	return dlm_lowcomms_close(nodeid);
+}
+
+int dlm_midcomms_start(void)
+{
+	return dlm_lowcomms_start();
+}
+
+void dlm_midcomms_stop(void)
+{
+	dlm_lowcomms_stop();
+}
+
 /*
  * Called from the low-level comms layer to process a buffer of
  * commands.
diff --git a/fs/dlm/midcomms.h b/fs/dlm/midcomms.h
index 61e90a921849..134c57430cdd 100644
--- a/fs/dlm/midcomms.h
+++ b/fs/dlm/midcomms.h
@@ -13,6 +13,16 @@
 #define __MIDCOMMS_DOT_H__
 
 int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int buflen);
+void *dlm_midcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc);
+void dlm_midcomms_commit_buffer(void *mh);
+void *dlm_midcomms_stateless_get_buffer(int nodeid, int len, gfp_t allocation,
+					char **ppc);
+void dlm_midcomms_stateless_commit_buffer(void *mh);
+void midcomms_add_member(int nodeid);
+void midcomms_remove_member(int nodeid);
+int dlm_midcomms_close(int nodeid);
+int dlm_midcomms_start(void);
+void dlm_midcomms_stop(void);
 
 #endif				/* __MIDCOMMS_DOT_H__ */
 
diff --git a/fs/dlm/rcom.c b/fs/dlm/rcom.c
index f5b1bd65728d..7a7d4a8e4706 100644
--- a/fs/dlm/rcom.c
+++ b/fs/dlm/rcom.c
@@ -28,14 +28,18 @@ static int rcom_response(struct dlm_ls *ls)
 }
 
 static int create_rcom(struct dlm_ls *ls, int to_nodeid, int type, int len,
-		       struct dlm_rcom **rc_ret, struct dlm_mhandle **mh_ret)
+		       struct dlm_rcom **rc_ret, struct dlm_mhandle **mh_ret,
+		       bool stateless)
 {
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
 	char *mb;
 	int mb_len = sizeof(struct dlm_rcom) + len;
 
-	mh = dlm_lowcomms_get_buffer(to_nodeid, mb_len, GFP_NOFS, &mb);
+	if (stateless)
+		mh = dlm_midcomms_stateless_get_buffer(to_nodeid, mb_len, GFP_NOFS, &mb);
+	else
+		mh = dlm_midcomms_get_buffer(to_nodeid, mb_len, GFP_NOFS, &mb);
 	if (!mh) {
 		log_print("create_rcom to %d type %d len %d ENOBUFS",
 			  to_nodeid, type, len);
@@ -62,10 +66,13 @@ static int create_rcom(struct dlm_ls *ls, int to_nodeid, int type, int len,
 }
 
 static void send_rcom(struct dlm_ls *ls, struct dlm_mhandle *mh,
-		      struct dlm_rcom *rc)
+		      struct dlm_rcom *rc, bool stateless)
 {
 	dlm_rcom_out(rc);
-	dlm_lowcomms_commit_buffer(mh);
+	if (stateless)
+		dlm_midcomms_stateless_commit_buffer(mh);
+	else
+		dlm_midcomms_commit_buffer(mh);
 }
 
 static void set_rcom_status(struct dlm_ls *ls, struct rcom_status *rs,
@@ -154,7 +161,7 @@ int dlm_rcom_status(struct dlm_ls *ls, int nodeid, uint32_t status_flags)
 
 retry:
 	error = create_rcom(ls, nodeid, DLM_RCOM_STATUS,
-			    sizeof(struct rcom_status), &rc, &mh);
+			    sizeof(struct rcom_status), &rc, &mh, true);
 	if (error)
 		goto out;
 
@@ -163,7 +170,7 @@ int dlm_rcom_status(struct dlm_ls *ls, int nodeid, uint32_t status_flags)
 	allow_sync_reply(ls, &rc->rc_id);
 	memset(ls->ls_recover_buf, 0, LOWCOMMS_MAX_TX_BUFFER_LEN);
 
-	send_rcom(ls, mh, rc);
+	send_rcom(ls, mh, rc, true);
 
 	error = dlm_wait_function(ls, &rcom_response);
 	disallow_sync_reply(ls);
@@ -219,7 +226,7 @@ static void receive_rcom_status(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 
  do_create:
 	error = create_rcom(ls, nodeid, DLM_RCOM_STATUS_REPLY,
-			    len, &rc, &mh);
+			    len, &rc, &mh, true);
 	if (error)
 		return;
 
@@ -246,7 +253,7 @@ static void receive_rcom_status(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 	spin_unlock(&ls->ls_recover_lock);
 
  do_send:
-	send_rcom(ls, mh, rc);
+	send_rcom(ls, mh, rc, true);
 }
 
 static void receive_sync_reply(struct dlm_ls *ls, struct dlm_rcom *rc_in)
@@ -277,7 +284,8 @@ int dlm_rcom_names(struct dlm_ls *ls, int nodeid, char *last_name, int last_len)
 	ls->ls_recover_nodeid = nodeid;
 
 retry:
-	error = create_rcom(ls, nodeid, DLM_RCOM_NAMES, last_len, &rc, &mh);
+	error = create_rcom(ls, nodeid, DLM_RCOM_NAMES, last_len, &rc, &mh,
+			    true);
 	if (error)
 		goto out;
 	memcpy(rc->rc_buf, last_name, last_len);
@@ -285,7 +293,7 @@ int dlm_rcom_names(struct dlm_ls *ls, int nodeid, char *last_name, int last_len)
 	allow_sync_reply(ls, &rc->rc_id);
 	memset(ls->ls_recover_buf, 0, LOWCOMMS_MAX_TX_BUFFER_LEN);
 
-	send_rcom(ls, mh, rc);
+	send_rcom(ls, mh, rc, true);
 
 	error = dlm_wait_function(ls, &rcom_response);
 	disallow_sync_reply(ls);
@@ -305,7 +313,8 @@ static void receive_rcom_names(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 	inlen = rc_in->rc_header.h_length - sizeof(struct dlm_rcom);
 	outlen = LOWCOMMS_MAX_TX_BUFFER_LEN - sizeof(struct dlm_rcom);
 
-	error = create_rcom(ls, nodeid, DLM_RCOM_NAMES_REPLY, outlen, &rc, &mh);
+	error = create_rcom(ls, nodeid, DLM_RCOM_NAMES_REPLY, outlen, &rc, &mh,
+			    true);
 	if (error)
 		return;
 	rc->rc_id = rc_in->rc_id;
@@ -313,7 +322,7 @@ static void receive_rcom_names(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 
 	dlm_copy_master_names(ls, rc_in->rc_buf, inlen, rc->rc_buf, outlen,
 			      nodeid);
-	send_rcom(ls, mh, rc);
+	send_rcom(ls, mh, rc, true);
 }
 
 int dlm_send_rcom_lookup(struct dlm_rsb *r, int dir_nodeid)
@@ -324,13 +333,13 @@ int dlm_send_rcom_lookup(struct dlm_rsb *r, int dir_nodeid)
 	int error;
 
 	error = create_rcom(ls, dir_nodeid, DLM_RCOM_LOOKUP, r->res_length,
-			    &rc, &mh);
+			    &rc, &mh, false);
 	if (error)
 		goto out;
 	memcpy(rc->rc_buf, r->res_name, r->res_length);
 	rc->rc_id = (unsigned long) r->res_id;
 
-	send_rcom(ls, mh, rc);
+	send_rcom(ls, mh, rc, false);
  out:
 	return error;
 }
@@ -342,7 +351,8 @@ static void receive_rcom_lookup(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 	int error, ret_nodeid, nodeid = rc_in->rc_header.h_nodeid;
 	int len = rc_in->rc_header.h_length - sizeof(struct dlm_rcom);
 
-	error = create_rcom(ls, nodeid, DLM_RCOM_LOOKUP_REPLY, 0, &rc, &mh);
+	error = create_rcom(ls, nodeid, DLM_RCOM_LOOKUP_REPLY, 0, &rc, &mh,
+			    false);
 	if (error)
 		return;
 
@@ -361,7 +371,7 @@ static void receive_rcom_lookup(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 	rc->rc_id = rc_in->rc_id;
 	rc->rc_seq_reply = rc_in->rc_seq;
 
-	send_rcom(ls, mh, rc);
+	send_rcom(ls, mh, rc, false);
 }
 
 static void receive_rcom_lookup_reply(struct dlm_ls *ls, struct dlm_rcom *rc_in)
@@ -410,7 +420,8 @@ int dlm_send_rcom_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
 	if (lkb->lkb_lvbptr)
 		len += ls->ls_lvblen;
 
-	error = create_rcom(ls, r->res_nodeid, DLM_RCOM_LOCK, len, &rc, &mh);
+	error = create_rcom(ls, r->res_nodeid, DLM_RCOM_LOCK, len, &rc, &mh,
+			    false);
 	if (error)
 		goto out;
 
@@ -418,7 +429,7 @@ int dlm_send_rcom_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
 	pack_rcom_lock(r, lkb, rl);
 	rc->rc_id = (unsigned long) r;
 
-	send_rcom(ls, mh, rc);
+	send_rcom(ls, mh, rc, false);
  out:
 	return error;
 }
@@ -433,7 +444,7 @@ static void receive_rcom_lock(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 	dlm_recover_master_copy(ls, rc_in);
 
 	error = create_rcom(ls, nodeid, DLM_RCOM_LOCK_REPLY,
-			    sizeof(struct rcom_lock), &rc, &mh);
+			    sizeof(struct rcom_lock), &rc, &mh, false);
 	if (error)
 		return;
 
@@ -444,7 +455,7 @@ static void receive_rcom_lock(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 	rc->rc_id = rc_in->rc_id;
 	rc->rc_seq_reply = rc_in->rc_seq;
 
-	send_rcom(ls, mh, rc);
+	send_rcom(ls, mh, rc, false);
 }
 
 /* If the lockspace doesn't exist then still send a status message
@@ -458,7 +469,7 @@ int dlm_send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in)
 	char *mb;
 	int mb_len = sizeof(struct dlm_rcom) + sizeof(struct rcom_config);
 
-	mh = dlm_lowcomms_get_buffer(nodeid, mb_len, GFP_NOFS, &mb);
+	mh = dlm_midcomms_get_buffer(nodeid, mb_len, GFP_NOFS, &mb);
 	if (!mh)
 		return -ENOBUFS;
 
@@ -479,7 +490,7 @@ int dlm_send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in)
 	rf->rf_lvblen = cpu_to_le32(~0U);
 
 	dlm_rcom_out(rc);
-	dlm_lowcomms_commit_buffer(mh);
+	dlm_midcomms_commit_buffer(mh);
 
 	return 0;
 }
diff --git a/fs/dlm/recoverd.c b/fs/dlm/recoverd.c
index 85e245392715..624fd54edeeb 100644
--- a/fs/dlm/recoverd.c
+++ b/fs/dlm/recoverd.c
@@ -16,6 +16,7 @@
 #include "ast.h"
 #include "recover.h"
 #include "lowcomms.h"
+#include "midcomms.h"
 #include "lock.h"
 #include "requestqueue.h"
 #include "recoverd.h"
@@ -53,6 +54,8 @@ static int ls_recover(struct dlm_ls *ls, struct dlm_recover *rv)
 	unsigned long start;
 	int error, neg = 0;
 
+	dlm_flush_removed_members(ls, rv);
+
 	log_rinfo(ls, "dlm_recover %llu", (unsigned long long)rv->seq);
 
 	mutex_lock(&ls->ls_recoverd_active);
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 10/20] fs: dlm: make buffer handling per msg

[Alexander Aring]

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.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lowcomms.c | 100 +++++++++++++++++++++++++++++++++++++++++-----
 fs/dlm/lowcomms.h |   5 ++-
 fs/dlm/midcomms.c |   8 +++-
 3 files changed, 101 insertions(+), 12 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 8c826e95493c..438badc2d870 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -114,6 +114,17 @@ struct writequeue_entry {
 	int end;
 	int users;
 	struct connection *con;
+	struct list_head msgs;
+	struct kref ref;
+};
+
+struct dlm_msg {
+	struct writequeue_entry *entry;
+	void *ppc;
+	int len;
+
+	struct list_head list;
+	struct kref ref;
 };
 
 struct dlm_node_addr {
@@ -956,12 +967,36 @@ static int accept_from_sock(struct listen_connection *con)
 	return result;
 }
 
-static void free_entry(struct writequeue_entry *e)
+static void dlm_page_release(struct kref *kref)
 {
+	struct writequeue_entry *e = container_of(kref, struct writequeue_entry,
+						  ref);
+
 	__free_page(e->page);
 	kfree(e);
 }
 
+static void dlm_msg_release(struct kref *kref)
+{
+	struct dlm_msg *msg = container_of(kref, struct dlm_msg, ref);
+
+	kref_put(&msg->entry->ref, dlm_page_release);
+	kfree(msg);
+}
+
+static void free_entry(struct writequeue_entry *e)
+{
+	struct dlm_msg *msg, *tmp;
+
+	list_for_each_entry_safe(msg, tmp, &e->msgs, list) {
+		list_del(&msg->list);
+		kref_put(&msg->ref, dlm_msg_release);
+	}
+
+	list_del(&e->list);
+	kref_put(&e->ref, dlm_page_release);
+}
+
 /*
  * writequeue_entry_complete - try to delete and free write queue entry
  * @e: write queue entry to try to delete
@@ -974,10 +1009,8 @@ static void writequeue_entry_complete(struct writequeue_entry *e, int completed)
 	e->offset += completed;
 	e->len -= completed;
 
-	if (e->len == 0 && e->users == 0) {
-		list_del(&e->list);
+	if (e->len == 0 && e->users == 0)
 		free_entry(e);
-	}
 }
 
 /*
@@ -1347,12 +1380,16 @@ static struct writequeue_entry *new_writequeue_entry(struct connection *con,
 
 	entry->con = con;
 	entry->users = 1;
+	kref_init(&entry->ref);
+	INIT_LIST_HEAD(&entry->msgs);
 
 	return entry;
 }
 
 static struct writequeue_entry *new_wq_entry(struct connection *con, int len,
-					     gfp_t allocation, char **ppc)
+					     gfp_t allocation, char **ppc,
+					     void (*cb)(void *buf, void *priv),
+					     void *priv)
 {
 	struct writequeue_entry *e;
 
@@ -1360,7 +1397,12 @@ static struct writequeue_entry *new_wq_entry(struct connection *con, int len,
 	if (!list_empty(&con->writequeue)) {
 		e = list_last_entry(&con->writequeue, struct writequeue_entry, list);
 		if (DLM_WQ_REMAIN_BYTES(e) >= len) {
+			kref_get(&e->ref);
+
 			*ppc = page_address(e->page) + e->end;
+			if (cb)
+				cb(*ppc, priv);
+
 			e->end += len;
 			e->users++;
 			spin_unlock(&con->writequeue_lock);
@@ -1374,19 +1416,26 @@ static struct writequeue_entry *new_wq_entry(struct connection *con, int len,
 	if (!e)
 		return NULL;
 
+	kref_get(&e->ref);
 	*ppc = page_address(e->page);
 	e->end += len;
 
 	spin_lock(&con->writequeue_lock);
+	if (cb)
+		cb(*ppc, priv);
+
 	list_add_tail(&e->list, &con->writequeue);
 	spin_unlock(&con->writequeue_lock);
 
 	return e;
 };
 
-void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
+void *dlm_lowcomms_new_buffer(int nodeid, int len, gfp_t allocation, char **ppc,
+			      void (*cb)(void *buf, void *priv), void *priv)
 {
+	struct writequeue_entry *e;
 	struct connection *con;
+	struct dlm_msg *msg;
 
 	if (len > DEFAULT_BUFFER_SIZE ||
 	    len < sizeof(struct dlm_header)) {
@@ -1399,16 +1448,36 @@ void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
 	if (!con)
 		return NULL;
 
-	return new_wq_entry(con, len, allocation, ppc);
+	msg = kzalloc(sizeof(*msg), allocation);
+	if (!msg)
+		return NULL;
+
+	kref_init(&msg->ref);
+
+	e = new_wq_entry(con, len, allocation, ppc, cb, priv);
+	if (!e) {
+		kfree(msg);
+		return NULL;
+	}
+
+	msg->ppc = *ppc;
+	msg->len = len;
+	msg->entry = e;
+
+	return msg;
 }
 
 void dlm_lowcomms_commit_buffer(void *mh)
 {
-	struct writequeue_entry *e = (struct writequeue_entry *)mh;
+	struct dlm_msg *msg = mh;
+	struct writequeue_entry *e = msg->entry;
 	struct connection *con = e->con;
 	int users;
 
 	spin_lock(&con->writequeue_lock);
+	list_add(&msg->list, &e->msgs);
+	kref_get(&msg->ref);
+
 	users = --e->users;
 	if (users)
 		goto out;
@@ -1424,6 +1493,20 @@ void dlm_lowcomms_commit_buffer(void *mh)
 	return;
 }
 
+void dlm_lowcomms_put_buffer(void *mh)
+{
+	struct dlm_msg *msg = mh;
+
+	kref_put(&msg->ref, dlm_msg_release);
+}
+
+void dlm_lowcomms_get_buffer(void *mh)
+{
+	struct dlm_msg *msg = mh;
+
+	kref_get(&msg->ref);
+}
+
 /* Send a message */
 static void send_to_sock(struct connection *con)
 {
@@ -1502,7 +1585,6 @@ static void clean_one_writequeue(struct connection *con)
 
 	spin_lock(&con->writequeue_lock);
 	list_for_each_entry_safe(e, safe, &con->writequeue, list) {
-		list_del(&e->list);
 		free_entry(e);
 	}
 	spin_unlock(&con->writequeue_lock);
diff --git a/fs/dlm/lowcomms.h b/fs/dlm/lowcomms.h
index f74888ed43b4..6417c5fca215 100644
--- a/fs/dlm/lowcomms.h
+++ b/fs/dlm/lowcomms.h
@@ -21,10 +21,13 @@ int dlm_lowcomms_start(void);
 void dlm_lowcomms_stop(void);
 void dlm_lowcomms_exit(void);
 int dlm_lowcomms_close(int nodeid);
-void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc);
+void *dlm_lowcomms_new_buffer(int nodeid, int len, gfp_t allocation, char **ppc,
+			      void (*cb)(void *buf, void *priv), void *priv);
 void dlm_lowcomms_commit_buffer(void *mh);
 int dlm_lowcomms_connect_node(int nodeid);
 int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr, int len);
+void dlm_lowcomms_put_buffer(void *mh);
+void dlm_lowcomms_get_buffer(void *mh);
 
 #endif				/* __LOWCOMMS_DOT_H__ */
 
diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index 717a3ed34f6a..e058e017c77d 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -32,23 +32,27 @@
 
 void *dlm_midcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
 {
-	return dlm_lowcomms_get_buffer(nodeid, len, allocation, ppc);
+	return dlm_lowcomms_new_buffer(nodeid, len, allocation, ppc, NULL,
+				       NULL);
 }
 
 void dlm_midcomms_commit_buffer(void *mh)
 {
 	dlm_lowcomms_commit_buffer(mh);
+	dlm_lowcomms_put_buffer(mh);
 }
 
 void *dlm_midcomms_stateless_get_buffer(int nodeid, int len, gfp_t allocation,
 					char **ppc)
 {
-	return dlm_lowcomms_get_buffer(nodeid, len, allocation, ppc);
+	return dlm_lowcomms_new_buffer(nodeid, len, allocation, ppc, NULL,
+				       NULL);
 }
 
 void dlm_midcomms_stateless_commit_buffer(void *mh)
 {
 	dlm_lowcomms_commit_buffer(mh);
+	dlm_lowcomms_put_buffer(mh);
 }
 
 void midcomms_add_member(int nodeid)
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 11/20] fs: dlm: make new buffer handling softirq ready

[Alexander Aring]

This patch makes the writequeue and message handling ready to be called
from a softirq by using spinlock handling to stop software interrupts
on local cpu while they are hold. The coming midcomms re-transmit
handling will introduce a timer which is using this functionality when
the timer expires.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lowcomms.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 438badc2d870..a84223b549ed 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -1393,7 +1393,7 @@ static struct writequeue_entry *new_wq_entry(struct connection *con, int len,
 {
 	struct writequeue_entry *e;
 
-	spin_lock(&con->writequeue_lock);
+	spin_lock_bh(&con->writequeue_lock);
 	if (!list_empty(&con->writequeue)) {
 		e = list_last_entry(&con->writequeue, struct writequeue_entry, list);
 		if (DLM_WQ_REMAIN_BYTES(e) >= len) {
@@ -1405,12 +1405,12 @@ static struct writequeue_entry *new_wq_entry(struct connection *con, int len,
 
 			e->end += len;
 			e->users++;
-			spin_unlock(&con->writequeue_lock);
+			spin_unlock_bh(&con->writequeue_lock);
 
 			return e;
 		}
 	}
-	spin_unlock(&con->writequeue_lock);
+	spin_unlock_bh(&con->writequeue_lock);
 
 	e = new_writequeue_entry(con, allocation);
 	if (!e)
@@ -1420,12 +1420,12 @@ static struct writequeue_entry *new_wq_entry(struct connection *con, int len,
 	*ppc = page_address(e->page);
 	e->end += len;
 
-	spin_lock(&con->writequeue_lock);
+	spin_lock_bh(&con->writequeue_lock);
 	if (cb)
 		cb(*ppc, priv);
 
 	list_add_tail(&e->list, &con->writequeue);
-	spin_unlock(&con->writequeue_lock);
+	spin_unlock_bh(&con->writequeue_lock);
 
 	return e;
 };
@@ -1474,7 +1474,7 @@ void dlm_lowcomms_commit_buffer(void *mh)
 	struct connection *con = e->con;
 	int users;
 
-	spin_lock(&con->writequeue_lock);
+	spin_lock_bh(&con->writequeue_lock);
 	list_add(&msg->list, &e->msgs);
 	kref_get(&msg->ref);
 
@@ -1483,13 +1483,13 @@ void dlm_lowcomms_commit_buffer(void *mh)
 		goto out;
 
 	e->len = DLM_WQ_LENGTH_BYTES(e);
-	spin_unlock(&con->writequeue_lock);
+	spin_unlock_bh(&con->writequeue_lock);
 
 	queue_work(send_workqueue, &con->swork);
 	return;
 
 out:
-	spin_unlock(&con->writequeue_lock);
+	spin_unlock_bh(&con->writequeue_lock);
 	return;
 }
 
@@ -1520,7 +1520,7 @@ static void send_to_sock(struct connection *con)
 	if (con->sock == NULL)
 		goto out_connect;
 
-	spin_lock(&con->writequeue_lock);
+	spin_lock_bh(&con->writequeue_lock);
 	for (;;) {
 		if (list_empty(&con->writequeue))
 			break;
@@ -1529,7 +1529,7 @@ static void send_to_sock(struct connection *con)
 		len = e->len;
 		offset = e->offset;
 		BUG_ON(len == 0 && e->users == 0);
-		spin_unlock(&con->writequeue_lock);
+		spin_unlock_bh(&con->writequeue_lock);
 
 		ret = 0;
 		if (len) {
@@ -1557,10 +1557,10 @@ static void send_to_sock(struct connection *con)
 			count = 0;
 		}
 
-		spin_lock(&con->writequeue_lock);
+		spin_lock_bh(&con->writequeue_lock);
 		writequeue_entry_complete(e, ret);
 	}
-	spin_unlock(&con->writequeue_lock);
+	spin_unlock_bh(&con->writequeue_lock);
 out:
 	mutex_unlock(&con->sock_mutex);
 	return;
@@ -1583,11 +1583,11 @@ static void clean_one_writequeue(struct connection *con)
 {
 	struct writequeue_entry *e, *safe;
 
-	spin_lock(&con->writequeue_lock);
+	spin_lock_bh(&con->writequeue_lock);
 	list_for_each_entry_safe(e, safe, &con->writequeue, list) {
 		free_entry(e);
 	}
-	spin_unlock(&con->writequeue_lock);
+	spin_unlock_bh(&con->writequeue_lock);
 }
 
 /* Called from recovery when it knows that a node has
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 12/20] fs: dlm: add functionality to re-transmit a message

[Alexander Aring]

This patch introduces a irqsafe retransmit functionality for a lowcomms
message handle. It's just allocates a new buffer and transmit it again.
To avoid another connection look some refactor was done to make a new
buffer allocation with a preexisting connection pointer.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lowcomms.c | 54 +++++++++++++++++++++++++++++++++++------------
 fs/dlm/lowcomms.h |  1 +
 2 files changed, 41 insertions(+), 14 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index a84223b549ed..f021dfecff91 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -1430,24 +1430,14 @@ static struct writequeue_entry *new_wq_entry(struct connection *con, int len,
 	return e;
 };
 
-void *dlm_lowcomms_new_buffer(int nodeid, int len, gfp_t allocation, char **ppc,
-			      void (*cb)(void *buf, void *priv), void *priv)
+static void *dlm_lowcomms_new_buffer_con(struct connection *con, int len,
+					 gfp_t allocation, char **ppc,
+					 void (*cb)(void *buf, void *priv),
+					 void *priv)
 {
 	struct writequeue_entry *e;
-	struct connection *con;
 	struct dlm_msg *msg;
 
-	if (len > DEFAULT_BUFFER_SIZE ||
-	    len < sizeof(struct dlm_header)) {
-		BUILD_BUG_ON(PAGE_SIZE < DEFAULT_BUFFER_SIZE);
-		log_print("failed to allocate a buffer of size %d", len);
-		return NULL;
-	}
-
-	con = nodeid2con(nodeid, allocation);
-	if (!con)
-		return NULL;
-
 	msg = kzalloc(sizeof(*msg), allocation);
 	if (!msg)
 		return NULL;
@@ -1467,6 +1457,25 @@ void *dlm_lowcomms_new_buffer(int nodeid, int len, gfp_t allocation, char **ppc,
 	return msg;
 }
 
+void *dlm_lowcomms_new_buffer(int nodeid, int len, gfp_t allocation, char **ppc,
+			      void (*cb)(void *buf, void *priv), void *priv)
+{
+	struct connection *con;
+
+	if (len > DEFAULT_BUFFER_SIZE ||
+	    len < sizeof(struct dlm_header)) {
+		BUILD_BUG_ON(PAGE_SIZE < DEFAULT_BUFFER_SIZE);
+		log_print("failed to allocate a buffer of size %d", len);
+		return NULL;
+	}
+
+	con = nodeid2con(nodeid, allocation);
+	if (!con)
+		return NULL;
+
+	return dlm_lowcomms_new_buffer_con(con, len, GFP_ATOMIC, ppc, cb, priv);
+}
+
 void dlm_lowcomms_commit_buffer(void *mh)
 {
 	struct dlm_msg *msg = mh;
@@ -1507,6 +1516,23 @@ void dlm_lowcomms_get_buffer(void *mh)
 	kref_get(&msg->ref);
 }
 
+/* irqsafe */
+void dlm_lowcomms_resend_buffer(void *mh)
+{
+	struct dlm_msg *msg = mh;
+	void *mh_new;
+	char *ppc;
+
+	mh_new = dlm_lowcomms_new_buffer_con(msg->entry->con, msg->len, GFP_ATOMIC,
+					     &ppc, NULL, NULL);
+	if (!mh_new)
+		return;
+
+	memcpy(ppc, msg->ppc, msg->len);
+	dlm_lowcomms_commit_buffer(mh_new);
+	dlm_lowcomms_put_buffer(mh_new);
+}
+
 /* Send a message */
 static void send_to_sock(struct connection *con)
 {
diff --git a/fs/dlm/lowcomms.h b/fs/dlm/lowcomms.h
index 6417c5fca215..30924b6f03e1 100644
--- a/fs/dlm/lowcomms.h
+++ b/fs/dlm/lowcomms.h
@@ -28,6 +28,7 @@ int dlm_lowcomms_connect_node(int nodeid);
 int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr, int len);
 void dlm_lowcomms_put_buffer(void *mh);
 void dlm_lowcomms_get_buffer(void *mh);
+void dlm_lowcomms_resend_buffer(void *mh);
 
 #endif				/* __LOWCOMMS_DOT_H__ */
 
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 13/20] fs: dlm: move out some hash functionality

[Alexander Aring]

This patch moves out some lowcomms hash functionality into lowcomms
header to provide them to other layers like midcomms as well.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lowcomms.c |  9 ---------
 fs/dlm/lowcomms.h | 10 ++++++++++
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index f021dfecff91..9a3899ad1765 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -59,7 +59,6 @@
 #include "config.h"
 
 #define NEEDED_RMEM (4*1024*1024)
-#define CONN_HASH_SIZE 32
 
 /* Number of messages to send before rescheduling */
 #define MAX_SEND_MSG_COUNT 25
@@ -165,14 +164,6 @@ static void sctp_connect_to_sock(struct connection *con);
 static void tcp_connect_to_sock(struct connection *con);
 static void dlm_tcp_shutdown(struct connection *con);
 
-/* This is deliberately very simple because most clusters have simple
-   sequential nodeids, so we should be able to go straight to a connection
-   struct in the array */
-static inline int nodeid_hash(int nodeid)
-{
-	return nodeid & (CONN_HASH_SIZE-1);
-}
-
 static struct connection *__find_con(int nodeid)
 {
 	int r, idx;
diff --git a/fs/dlm/lowcomms.h b/fs/dlm/lowcomms.h
index 30924b6f03e1..8286531f9a9e 100644
--- a/fs/dlm/lowcomms.h
+++ b/fs/dlm/lowcomms.h
@@ -13,6 +13,16 @@
 #define __LOWCOMMS_DOT_H__
 
 #define LOWCOMMS_MAX_TX_BUFFER_LEN	4096
+#define CONN_HASH_SIZE 32
+
+/* This is deliberately very simple because most clusters have simple
+ * sequential nodeids, so we should be able to go straight to a connection
+ * struct in the array
+ */
+static inline int nodeid_hash(int nodeid)
+{
+	return nodeid & (CONN_HASH_SIZE-1);
+}
 
 /* switch to check if dlm is running */
 extern int dlm_allow_conn;
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 14/20] fs: dlm: remove unaligned memory access handling

[Alexander Aring]

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 <aahringo@redhat.com>
---
 fs/dlm/midcomms.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index e058e017c77d..45dd3d7d857f 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -22,8 +22,6 @@
  * into packets and sends them to the comms layer.
  */
 
-#include <asm/unaligned.h>
-
 #include "dlm_internal.h"
 #include "lowcomms.h"
 #include "config.h"
@@ -93,13 +91,22 @@ int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
 	while (len >= sizeof(struct dlm_header)) {
 		hd = (struct dlm_header *)ptr;
 
-		/* no message should be more than this otherwise we
-		 * cannot deliver this message to upper layers
+		/* no message should be more than DEFAULT_BUFFER_SIZE or
+		 * less than dlm_header size.
+		 *
+		 * Some messages does not have a 8 byte length boundary yet
+		 * which can occur in a unaligned memory access of some dlm
+		 * messages. However this problem need to be fixed at the
+		 * sending side, for now it seems nobody run into architecture
+		 * related issues yet but it slows down some processing.
+		 * Fixing this issue should be scheduled in future by doing
+		 * the next major version bump.
 		 */
-		msglen = get_unaligned_le16(&hd->h_length);
-		if (msglen > DEFAULT_BUFFER_SIZE) {
-			log_print("received invalid length header: %u, will abort message parsing",
-				  msglen);
+		msglen = le16_to_cpu(hd->h_length);
+		if (msglen > DEFAULT_BUFFER_SIZE ||
+		    msglen < sizeof(struct dlm_header)) {
+			log_print("received invalid length header: %u from node %d, will abort message parsing",
+				  msglen, nodeid);
 			return -EBADMSG;
 		}
 
@@ -132,14 +139,6 @@ int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
 			goto skip;
 		}
 
-		/* for aligned memory access, we just copy current message
-		 * to begin of the buffer which contains already parsed buffer
-		 * data and should provide align access for upper layers
-		 * because the start address of the buffer has a aligned
-		 * address. This memmove can be removed when the upperlayer
-		 * is capable of unaligned memory access.
-		 */
-		memmove(buf, ptr, msglen);
 		dlm_receive_buffer((union dlm_packet *)buf, nodeid);
 
 skip:
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 15/20] fs: dlm: add union in dlm header for lockspace id

[Alexander Aring]

This patch adds union inside the lockspace id to handle it also for
another use case for a different dlm command.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/dlm_internal.h | 5 ++++-
 fs/dlm/lock.c         | 8 ++++----
 fs/dlm/midcomms.c     | 1 -
 fs/dlm/rcom.c         | 4 ++--
 fs/dlm/util.c         | 6 ++++--
 5 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index 04fe9f525ac7..917de7367a32 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -377,7 +377,10 @@ static inline int rsb_flag(struct dlm_rsb *r, enum rsb_flags flag)
 
 struct dlm_header {
 	uint32_t		h_version;
-	uint32_t		h_lockspace;
+	union {
+		/* for DLM_MSG and DLM_RCOM */
+		uint32_t	h_lockspace;
+	} u;
 	uint32_t		h_nodeid;	/* nodeid of sender */
 	uint16_t		h_length;
 	uint8_t			h_cmd;		/* DLM_MSG, DLM_RCOM */
diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index b3fd823009f4..daa5747c8556 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -3544,7 +3544,7 @@ static int _create_message(struct dlm_ls *ls, int mb_len,
 	ms = (struct dlm_message *) mb;
 
 	ms->m_header.h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
-	ms->m_header.h_lockspace = ls->ls_global_id;
+	ms->m_header.u.h_lockspace = ls->ls_global_id;
 	ms->m_header.h_nodeid = dlm_our_nodeid();
 	ms->m_header.h_length = mb_len;
 	ms->m_header.h_cmd = DLM_MSG;
@@ -5038,16 +5038,16 @@ void dlm_receive_buffer(union dlm_packet *p, int nodeid)
 
 	if (hd->h_nodeid != nodeid) {
 		log_print("invalid h_nodeid %d from %d lockspace %x",
-			  hd->h_nodeid, nodeid, hd->h_lockspace);
+			  hd->h_nodeid, nodeid, hd->u.h_lockspace);
 		return;
 	}
 
-	ls = dlm_find_lockspace_global(hd->h_lockspace);
+	ls = dlm_find_lockspace_global(hd->u.h_lockspace);
 	if (!ls) {
 		if (dlm_config.ci_log_debug) {
 			printk_ratelimited(KERN_DEBUG "dlm: invalid lockspace "
 				"%u from %d cmd %d type %d\n",
-				hd->h_lockspace, nodeid, hd->h_cmd, type);
+				hd->u.h_lockspace, nodeid, hd->h_cmd, type);
 		}
 
 		if (hd->h_cmd == DLM_RCOM && type == DLM_RCOM_STATUS)
diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index 45dd3d7d857f..71a1f0c910b3 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -149,4 +149,3 @@ int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
 
 	return ret;
 }
-
diff --git a/fs/dlm/rcom.c b/fs/dlm/rcom.c
index 7a7d4a8e4706..06f7a5f1d99d 100644
--- a/fs/dlm/rcom.c
+++ b/fs/dlm/rcom.c
@@ -49,7 +49,7 @@ static int create_rcom(struct dlm_ls *ls, int to_nodeid, int type, int len,
 	rc = (struct dlm_rcom *) mb;
 
 	rc->rc_header.h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
-	rc->rc_header.h_lockspace = ls->ls_global_id;
+	rc->rc_header.u.h_lockspace = ls->ls_global_id;
 	rc->rc_header.h_nodeid = dlm_our_nodeid();
 	rc->rc_header.h_length = mb_len;
 	rc->rc_header.h_cmd = DLM_RCOM;
@@ -476,7 +476,7 @@ int dlm_send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in)
 	rc = (struct dlm_rcom *) mb;
 
 	rc->rc_header.h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
-	rc->rc_header.h_lockspace = rc_in->rc_header.h_lockspace;
+	rc->rc_header.u.h_lockspace = rc_in->rc_header.u.h_lockspace;
 	rc->rc_header.h_nodeid = dlm_our_nodeid();
 	rc->rc_header.h_length = mb_len;
 	rc->rc_header.h_cmd = DLM_RCOM;
diff --git a/fs/dlm/util.c b/fs/dlm/util.c
index 74a8c5bfe9b5..58acbcc2081a 100644
--- a/fs/dlm/util.c
+++ b/fs/dlm/util.c
@@ -23,7 +23,8 @@
 void header_out(struct dlm_header *hd)
 {
 	hd->h_version		= cpu_to_le32(hd->h_version);
-	hd->h_lockspace		= cpu_to_le32(hd->h_lockspace);
+	/* does it for others u32 in union as well */
+	hd->u.h_lockspace	= cpu_to_le32(hd->u.h_lockspace);
 	hd->h_nodeid		= cpu_to_le32(hd->h_nodeid);
 	hd->h_length		= cpu_to_le16(hd->h_length);
 }
@@ -31,7 +32,8 @@ void header_out(struct dlm_header *hd)
 void header_in(struct dlm_header *hd)
 {
 	hd->h_version		= le32_to_cpu(hd->h_version);
-	hd->h_lockspace		= le32_to_cpu(hd->h_lockspace);
+	/* does it for others u32 in union as well */
+	hd->u.h_lockspace	= le32_to_cpu(hd->u.h_lockspace);
 	hd->h_nodeid		= le32_to_cpu(hd->h_nodeid);
 	hd->h_length		= le16_to_cpu(hd->h_length);
 }
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 16/20] fs: dlm: add per node receive flush

[Alexander Aring]

This patch will add a functionality to flush pending dlm messages from
the receiving workqueue. Upcoming patches will use it to make sure that
nothing can be received e.g. after a node gets removed from the nodes
hash. Receiving messages will occur into a node lookup which might
create an node for the hash again.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lowcomms.c | 9 +++++++++
 fs/dlm/lowcomms.h | 1 +
 2 files changed, 10 insertions(+)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 9a3899ad1765..0e4cbabc680f 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -1607,6 +1607,15 @@ static void clean_one_writequeue(struct connection *con)
 	spin_unlock_bh(&con->writequeue_lock);
 }
 
+void dlm_lowcomms_rx_flush(int nodeid)
+{
+	struct connection *con;
+
+	con = nodeid2con(nodeid, 0);
+	if (con)
+		flush_work(&con->rwork);
+}
+
 /* Called from recovery when it knows that a node has
    left the cluster */
 int dlm_lowcomms_close(int nodeid)
diff --git a/fs/dlm/lowcomms.h b/fs/dlm/lowcomms.h
index 8286531f9a9e..c4c789a68cf6 100644
--- a/fs/dlm/lowcomms.h
+++ b/fs/dlm/lowcomms.h
@@ -39,6 +39,7 @@ int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr, int len);
 void dlm_lowcomms_put_buffer(void *mh);
 void dlm_lowcomms_get_buffer(void *mh);
 void dlm_lowcomms_resend_buffer(void *mh);
+void dlm_lowcomms_rx_flush(int nodeid);
 
 #endif				/* __LOWCOMMS_DOT_H__ */
 
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 17/20] fs: dlm: add reliable connection if reconnect

[Alexander Aring]

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:

A new DLM message to synchronize pending message to the other dlm end if
the node want to disconnects. Each side waits until it receives this
message and disconnects. It's important that this message has nothing to
do with the application logic because it might run in a timeout if
acknowledge messages are dropped.

To explain the basic functionality take a look into the
dlm_midcomms_receive_buffer() function. This function will take care
that dlm messages are delivered according to their sequence numbers and
request re-transmission via sending acknowledge messages. However there
exists three cases:

1. sequence number is the one which is expected. That means everything
   is working fine. Additional there is always a check if the next
   message was already queued for future, this will occur when there was
   some messages drops before.

2. A sequence number is in the future, in this case we queue it for might
   future delivery, see case 1.

3. A sequence number is in the past, in this case we drop this message
   because it was already delivered.

To send acknowledge we always send the sequence number which is
expected, if the other node sends multiple acknowledge for the same
sequence numbers it will trigger a re-transmission. In case no acknowledge
is send back, a timer with a timeout handling is running and will trigger
a re-tranmission as well. Sending multiple ack's with the same sequence or
messages with the same sequence should not have any effects that breaks
dlm. Only messages in the far future can break dlm, that's why important
that the closing connection is right synchronized with DLM_FIN which
also resets the sequence numbers.

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 <aahringo@redhat.com>
---
 fs/dlm/dlm_internal.h |   30 +-
 fs/dlm/lowcomms.h     |    7 +-
 fs/dlm/midcomms.c     | 1232 +++++++++++++++++++++++++++++++++++++++--
 3 files changed, 1216 insertions(+), 53 deletions(-)

diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index 917de7367a32..da2297705713 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -368,18 +368,26 @@ static inline int rsb_flag(struct dlm_rsb *r, enum rsb_flags flag)
 /* dlm_header is first element of all structs sent between nodes */
 
 #define DLM_HEADER_MAJOR	0x00030000
-#define DLM_HEADER_MINOR	0x00000001
+#define DLM_HEADER_MINOR	0x00000002
+
+#define DLM_VERSION_3_1		0x00030001
+#define DLM_VERSION_3_2		0x00030002
 
 #define DLM_HEADER_SLOTS	0x00000001
 
 #define DLM_MSG			1
 #define DLM_RCOM		2
+#define DLM_OPTS		3
+#define DLM_ACK			4
+#define DLM_FIN			5
 
 struct dlm_header {
 	uint32_t		h_version;
 	union {
 		/* for DLM_MSG and DLM_RCOM */
 		uint32_t	h_lockspace;
+		/* for DLM_ACK and DLM_OPTS */
+		uint32_t	h_seq;
 	} u;
 	uint32_t		h_nodeid;	/* nodeid of sender */
 	uint16_t		h_length;
@@ -387,7 +395,6 @@ struct dlm_header {
 	uint8_t			h_pad;
 };
 
-
 #define DLM_MSG_REQUEST		1
 #define DLM_MSG_CONVERT		2
 #define DLM_MSG_UNLOCK		3
@@ -455,10 +462,29 @@ struct dlm_rcom {
 	char			rc_buf[];
 };
 
+struct dlm_opt_header {
+	uint16_t	t_type;
+	uint16_t	t_length;
+	uint32_t	o_pad;
+	/* need to be 8 byte aligned */
+	char		t_value[];
+};
+
+/* encapsulation header */
+struct dlm_opts {
+	struct dlm_header	o_header;
+	uint8_t			o_nextcmd;
+	uint8_t			o_pad;
+	uint16_t		o_optlen;
+	uint32_t		o_pad2;
+	char			o_opts[];
+};
+
 union dlm_packet {
 	struct dlm_header	header;		/* common to other two */
 	struct dlm_message	message;
 	struct dlm_rcom		rcom;
+	struct dlm_opts		opts;
 };
 
 #define DLM_RSF_NEED_SLOTS	0x00000001
diff --git a/fs/dlm/lowcomms.h b/fs/dlm/lowcomms.h
index c4c789a68cf6..53b993f58508 100644
--- a/fs/dlm/lowcomms.h
+++ b/fs/dlm/lowcomms.h
@@ -12,7 +12,12 @@
 #ifndef __LOWCOMMS_DOT_H__
 #define __LOWCOMMS_DOT_H__
 
-#define LOWCOMMS_MAX_TX_BUFFER_LEN	4096
+#include "dlm_internal.h"
+
+#define DLM_MIDCOMMS_OPT_LEN		sizeof(struct dlm_opts)
+#define LOWCOMMS_MAX_TX_BUFFER_LEN	(DEFAULT_BUFFER_SIZE - \
+					 DLM_MIDCOMMS_OPT_LEN)
+
 #define CONN_HASH_SIZE 32
 
 /* This is deliberately very simple because most clusters have simple
diff --git a/fs/dlm/midcomms.c b/fs/dlm/midcomms.c
index 71a1f0c910b3..d6487f0142e6 100644
--- a/fs/dlm/midcomms.c
+++ b/fs/dlm/midcomms.c
@@ -3,7 +3,7 @@
 *******************************************************************************
 **
 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
-**  Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
+**  Copyright (C) 2004-2021 Red Hat, Inc.  All rights reserved.
 **
 **
 *******************************************************************************
@@ -12,68 +12,845 @@
 /*
  * midcomms.c
  *
- * This is the appallingly named "mid-level" comms layer.
+ * This is the appallingly named "mid-level" comms layer. It takes care
+ * about deliver an on application layer "reliable" communication above
+ * the used lowcomms transport layer.
  *
- * Its purpose is to take packets from the "real" comms layer,
- * split them up into packets and pass them to the interested
- * part of the locking mechanism.
+ * How it works:
+ *
+ * The basic implementation about the implemented re-transmission algorithm
+ * is based on:
+ *
+ * https://web.archive.org/web/20200813052233/https://www.isi.edu/nsnam/DIRECTED_RESEARCH/DR_WANIDA/DR/JavisInActionFastRetransmitFrame.html
+ *
+ * There are two cases when a re-transmission occurs, both are described in
+ * the link above:
+ *
+ * - Multiple acks for the same sequence number are received, known as
+ *   "fast re-transmit".
+ * - Ack timeout, if we don't receive an ack in a time of "DLM_RTO". Note
+ *   that the this timeout will only be checked in the re-transmission
+ *   time which runs ever "DLM_RTO_TIMER".
+ *
+ * Each node has a send_queue and recv_queue. The send_queue contains a
+ * reference to each msg handle of lowcomms and keeps the message alive
+ * so far it has not been acked. This is necessary to keep the message
+ * for a possible re-transmission.
+ *
+ * The recv_queue is used to keep messages saved which are having a
+ * sequence number in the future of the expected sequence number. If
+ * the expected sequence number and we have the next sequence number
+ * inside this queue it will be delivered to the upper layer. This
+ * queue should have entries only if there was a drop.
+ *
+ * How version detection works:
+ *
+ * Due the fact that dlm has pre-configured node addresses on every side
+ * it is it's nature that every side connects at starts to transmit
+ * dlm messages. However DLM_RCOM_NAMES, DLM_RCOM_STATUS and their replies
+ * are the first messages which are exchanges. Due backwards compatibility
+ * these messages are not covered by the midcomms re-transmission layer.
+ * However these messages have their own re-transmission handling on inside
+ * the dlm application layer as well. The version field of every node will
+ * be set on RCOM messages as soon as they arrived and the node isn't inside
+ * the nodes hash. There exists also logic to detect version mismatched if
+ * something weird going on or the first messages isn't a RCOM one.
+ *
+ * How ack handling basically works:
+ *
+ * We ack every message with the "expected sequence number". A connection
+ * starts with the sequence number of 0. Receiving an ack will ack all
+ * dlm messages below it's sequence number. It's possible that an ack
+ * message can ack multiple dlm messages as the other side will send an
+ * sequence number back of it's expected sequence number. If there are
+ * multiple ack's received with the same sequence number it means that
+ * there was a drop and the other side telling us which message was
+ * dropped. The parameter "DLM_RETRANS_ACK_COUNT" can be used to change
+ * the amount of how many ack we need to received. It's 3 but 2
+ * should be fine as well as it's ery unlikely that we have out of order
+ * issues as RFC 2001 says to use 3. I can only think about multiple
+ * re-connection in a row where with drops which we might get ordering
+ * issues.
+ *
+ * In cases where everything nobody transmits any messages anymore but
+ * there was drops the re-transmission timer will kick in to resend
+ * messages which have an ack timeout.
+ *
+ * Sequence number cases:
+ *
+ * As a message arrived in function "dlm_midcomms_receive_buffer()" will
+ * detect if a message is:
+ *
+ * - as expected => everything is fine
+ * - in the future => there was a drop, queue msg in recv_queue queue
+ * - in the past => ignore that message, because already delivered
+ *
+ * However we will always send an ack message to the other node to signal
+ * which is the current expected sequence number. This either acks
+ * messages or re-transmit on the other side, see ack handling.
+ *
+ * Termination:
+ *
+ * As this layer was implemented there exists a problem with drops during
+ * connection termination. At midcomms_stop() call which occurs at the
+ * last dlm lockspace release the other side was still sending dlm
+ * messages after the connection was terminated. With the re-transmission
+ * layer this ends in a endless re-transmission behaviour. However that
+ * is an issue with the dlm protocol and was solved by introducing the
+ * DLM_FIN message command to synchronize the termination and make sure
+ * both nodes has nothing to send anymore. The parameter
+ * "DLM_QUEUE_TIMEOUT" defines the timeout to wait for pending dlm
+ * messages if Termination occurs. The parameter "DLM_FIN_TIMEOUT" will
+ * wait that the other side has no pending dlm messages anymore.
+ *
+ * Future improvements:
+ *
+ * There exists some known issues/improvements of the dlm handling. Some
+ * of them should be done in a next major dlm version bump which makes
+ * it incompatible with previous versions.
+ *
+ * Unaligned memory access:
+ *
+ * There exists cases when the dlm message buffer length is not aligned
+ * to 8 byte. However seems nobody detected any problem with it. This
+ * can be fixed in the next major version bump of dlm.
+ *
+ * Version detection:
+ *
+ * The version detection and how it's done is related to backwards
+ * compatibility. There exists better ways to make a better handling.
+ * However this should be changed in the next major version bump of dlm.
+ *
+ * Ack handling:
+ *
+ * Currently we send an ack message for every dlm message. However we
+ * can ack multiple dlm messages with one ack by just delaying the ack
+ * message. Will reduce some traffic but makes the drop detection slower.
  *
- * It also takes messages from the locking layer, formats them
- * into packets and sends them to the comms layer.
  */
 
+/* Debug switch to enable a 5 seconds sleep waiting of a termination.
+ * This can be useful to test fencing while termination is running.
+ * This requires a setup with only gfs2 as dlm user, so that the
+ * last umount will terminate the connection.
+ *
+ * However it became useful to test, while the 5 seconds block in umount
+ * just press the reset button. In a lot of dropping the termination
+ * process can could take several seconds.
+ */
+#define DLM_DEBUG_FENCE_TERMINATION	0
+
 #include "dlm_internal.h"
 #include "lowcomms.h"
 #include "config.h"
 #include "lock.h"
+#include "util.h"
 #include "midcomms.h"
 
-void *dlm_midcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
+/* init value for sequence numbers for testing purpose only e.g. overflows */
+#define DLM_SEQ_INIT		0
+/* if we get duplicates amount of acks we will start retransmit */
+#define DLM_RETRANS_ACK_COUNT	3
+/* timer timeout to start retransmit if we don't get an ack back */
+#define DLM_RTO			msecs_to_jiffies(30 * 1000)
+#define DLM_RTO_TIMER		msecs_to_jiffies(60 * 1000)
+/* 10 minutes wait to sync ending of dlm */
+#define DLM_QUEUE_TIMEOUT	msecs_to_jiffies(10 * 60 * 1000)
+/* 3 minutes wait to wait for a fin message */
+#define DLM_FIN_TIMEOUT		msecs_to_jiffies(3 * 60 * 1000)
+#define DLM_VERSION_NOT_SET	0
+
+struct midcomms_node {
+	int nodeid;
+	uint32_t version;
+	uint32_t seq_send;
+	uint32_t seq_next;
+	uint32_t seq_last;
+	/* note: this list may not sorted according to their seq */
+	struct list_head send_queue;
+	struct list_head recv_queue;
+	spinlock_t send_queue_lock;
+	atomic_t send_queue_cnt;
+	atomic_t recv_queue_cnt;
+#define DLM_NODE_FLAG_FIN	1
+#define DLM_NODE_FLAG_CLOSE	2
+	unsigned long flags;
+	wait_queue_head_t fin_wait;
+	/* counts how many lockspaces are using this node
+	 * this refcount is necessary to determine if the
+	 * node wants to disconnect.
+	 */
+	int users;
+
+	struct hlist_node hlist;
+	struct rcu_head rcu;
+};
+
+struct dlm_send_msg {
+	const struct dlm_header *inner_hd;
+	struct midcomms_node *node;
+	struct dlm_opts *opts;
+	unsigned long timeout;
+	int ack_count;
+	uint32_t seq;
+	void *mh;
+
+	struct list_head list;
+	struct rcu_head rcu;
+};
+
+struct dlm_recv_msg {
+	union dlm_packet *p;
+	uint32_t seq;
+
+	struct list_head list;
+};
+
+static struct timer_list dlm_retransmit_timer;
+
+static struct hlist_head node_hash[CONN_HASH_SIZE];
+static DEFINE_SPINLOCK(nodes_lock);
+static DEFINE_MUTEX(close_lock);
+DEFINE_STATIC_SRCU(nodes_srcu);
+
+static struct midcomms_node *__find_node(int nodeid, int r)
 {
-	return dlm_lowcomms_new_buffer(nodeid, len, allocation, ppc, NULL,
-				       NULL);
+	struct midcomms_node *node;
+	int idx;
+
+	idx = srcu_read_lock(&nodes_srcu);
+	hlist_for_each_entry_rcu(node, &node_hash[r], hlist) {
+		if (node->nodeid == nodeid) {
+			srcu_read_unlock(&nodes_srcu, idx);
+			return node;
+		}
+	}
+	srcu_read_unlock(&nodes_srcu, idx);
+
+	return NULL;
 }
 
-void dlm_midcomms_commit_buffer(void *mh)
+static struct midcomms_node *nodeid2node(int nodeid, gfp_t alloc)
 {
-	dlm_lowcomms_commit_buffer(mh);
-	dlm_lowcomms_put_buffer(mh);
+	struct midcomms_node *node, *tmp;
+	int r = nodeid_hash(nodeid);
+
+	node = __find_node(nodeid, r);
+	if (node || !alloc)
+		return node;
+
+	node = kzalloc(sizeof(*node), alloc);
+	if (!node)
+		return NULL;
+
+	node->nodeid = nodeid;
+	node->seq_next = DLM_SEQ_INIT;
+	node->seq_send = DLM_SEQ_INIT;
+	node->seq_last = DLM_SEQ_INIT;
+	spin_lock_init(&node->send_queue_lock);
+	atomic_set(&node->send_queue_cnt, 0);
+	INIT_LIST_HEAD(&node->send_queue);
+	atomic_set(&node->recv_queue_cnt, 0);
+	INIT_LIST_HEAD(&node->recv_queue);
+	init_waitqueue_head(&node->fin_wait);
+
+	spin_lock(&nodes_lock);
+	/* check again if there was somebody else
+	 * earlier here to add the node
+	 */
+	tmp = __find_node(nodeid, r);
+	if (tmp) {
+		spin_unlock(&nodes_lock);
+		kfree(node);
+		return tmp;
+	}
+
+	hlist_add_head_rcu(&node->hlist, &node_hash[r]);
+	spin_unlock(&nodes_lock);
+
+	return node;
 }
 
-void *dlm_midcomms_stateless_get_buffer(int nodeid, int len, gfp_t allocation,
-					char **ppc)
+static int dlm_send_ack(int nodeid, uint32_t seq)
 {
-	return dlm_lowcomms_new_buffer(nodeid, len, allocation, ppc, NULL,
-				       NULL);
+	int mb_len = sizeof(struct dlm_header);
+	struct dlm_header *m_header;
+	char *ppc;
+	void *mh;
+
+	mh = dlm_midcomms_stateless_get_buffer(nodeid, mb_len, GFP_NOFS, &ppc);
+	if (!mh)
+		return -ENOMEM;
+
+	m_header = (struct dlm_header *)ppc;
+
+	m_header->h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
+	m_header->h_nodeid = dlm_our_nodeid();
+	m_header->h_length = mb_len;
+	m_header->h_cmd = DLM_ACK;
+	m_header->u.h_seq = seq;
+
+	header_out(m_header);
+	dlm_midcomms_stateless_commit_buffer(mh);
+
+	return 0;
 }
 
-void dlm_midcomms_stateless_commit_buffer(void *mh)
+static int dlm_send_fin(int nodeid)
 {
-	dlm_lowcomms_commit_buffer(mh);
-	dlm_lowcomms_put_buffer(mh);
+	int mb_len = sizeof(struct dlm_header);
+	struct dlm_header *m_header;
+	char *ppc;
+	void *mh;
+
+	mh = dlm_midcomms_get_buffer(nodeid, mb_len, GFP_NOFS, &ppc);
+	if (!mh)
+		return -ENOMEM;
+
+	m_header = (struct dlm_header *)ppc;
+
+	m_header->h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
+	m_header->h_nodeid = dlm_our_nodeid();
+	m_header->h_length = mb_len;
+	m_header->h_cmd = DLM_FIN;
+
+	header_out(m_header);
+	dlm_midcomms_commit_buffer(mh);
+
+	return 0;
 }
 
-void midcomms_add_member(int nodeid)
+static void dlm_send_msg_release(struct rcu_head *rcu)
 {
+	struct dlm_send_msg *msg = container_of(rcu, struct dlm_send_msg, rcu);
+
+	dlm_lowcomms_put_buffer(msg->mh);
+	kfree(msg);
 }
 
-void midcomms_remove_member(int nodeid)
+/* send_queue_lock must be held */
+static void dlm_send_msg_del(struct midcomms_node *node,
+			     struct dlm_send_msg *msg)
 {
+	list_del_rcu(&msg->list);
+	if (atomic_dec_and_test(&node->send_queue_cnt))
+		wake_up(&node->fin_wait);
+
+	call_rcu(&msg->rcu, dlm_send_msg_release);
 }
 
-int dlm_midcomms_close(int nodeid)
+static void dlm_send_queue_flush(struct midcomms_node *node)
 {
-	return dlm_lowcomms_close(nodeid);
+	struct dlm_send_msg *msg;
+
+	rcu_read_lock();
+	spin_lock(&node->send_queue_lock);
+	list_for_each_entry_rcu(msg, &node->send_queue, list) {
+		dlm_send_msg_del(node, msg);
+	}
+	spin_unlock(&node->send_queue_lock);
+	rcu_read_unlock();
 }
 
-int dlm_midcomms_start(void)
+static void dlm_recv_queue_flush(struct midcomms_node *node)
 {
-	return dlm_lowcomms_start();
+	struct dlm_recv_msg *msg, *tmp;
+
+	list_for_each_entry_safe(msg, tmp, &node->recv_queue, list) {
+		list_del(&msg->list);
+		if (atomic_dec_and_test(&node->recv_queue_cnt))
+			wake_up(&node->fin_wait);
+
+		kfree(msg->p);
+		kfree(msg);
+	}
 }
 
-void dlm_midcomms_stop(void)
+static void dlm_midcomms_seq_receive_buffer(struct midcomms_node *node,
+					    union dlm_packet *p)
 {
-	dlm_lowcomms_stop();
+	dlm_receive_buffer(p, node->nodeid);
+	node->seq_next++;
+}
+
+static void dlm_overflow_upper_ack(struct midcomms_node *node)
+{
+	struct dlm_send_msg *msg;
+
+	/* stop all seq transmissions for this node to ack all upper */
+	spin_lock(&node->send_queue_lock);
+	list_for_each_entry_rcu(msg, &node->send_queue, list) {
+		if (msg->seq > node->seq_send) {
+			log_print("seq overflow handling, will ack message %u from node %d",
+				  msg->seq, node->nodeid);
+			dlm_send_msg_del(node, msg);
+		}
+	}
+	spin_unlock(&node->send_queue_lock);
+}
+
+static void dlm_receive_ack(struct midcomms_node *node, uint32_t seq)
+{
+	struct dlm_send_msg *msg;
+
+	rcu_read_lock();
+	if (seq < node->seq_last) {
+		log_print("dlm seq overflow detected from node %d",
+			  node->nodeid);
+		dlm_overflow_upper_ack(node);
+	}
+
+	list_for_each_entry_rcu(msg, &node->send_queue, list) {
+		if (msg->seq < seq) {
+			spin_lock(&node->send_queue_lock);
+			dlm_send_msg_del(node, msg);
+			spin_unlock(&node->send_queue_lock);
+		} else if (msg->seq == seq) {
+			msg->ack_count++;
+			if (msg->ack_count >= DLM_RETRANS_ACK_COUNT) {
+				log_print("retransmit because multiple acks received. message seq %u, nodeid: %d",
+					  seq, node->nodeid);
+				dlm_lowcomms_resend_buffer(msg->mh);
+			}
+		}
+	}
+	rcu_read_unlock();
+
+	/* for overflow detection */
+	node->seq_last = seq;
+}
+
+static struct dlm_recv_msg *dlm_recv_create_msg(const union dlm_packet *p,
+						uint32_t seq)
+{
+	int mb_len = le16_to_cpu(p->header.h_length);
+	struct dlm_recv_msg *msg;
+
+	msg = kzalloc(sizeof(*msg), GFP_NOFS);
+	if (!msg)
+		return NULL;
+
+	msg->p = kzalloc(mb_len, GFP_NOFS);
+	if (!msg)
+		return NULL;
+
+	memcpy(msg->p, p, mb_len);
+	msg->seq = seq;
+
+	return msg;
+}
+
+static struct dlm_recv_msg *dlm_recv_get_msg_by_seq(struct midcomms_node *node,
+						    uint32_t seq)
+{
+	struct dlm_recv_msg *msg;
+
+	list_for_each_entry(msg, &node->recv_queue, list) {
+		if (msg->seq == seq)
+			return msg;
+	}
+
+	return NULL;
+}
+
+static int dlm_recv_queue_future_msg(struct midcomms_node *node,
+				     const union dlm_packet *p,
+				     uint32_t seq)
+{
+	struct dlm_recv_msg *msg;
+
+	/* check if we already got the message */
+	msg = dlm_recv_get_msg_by_seq(node, seq);
+	if (msg)
+		return 0;
+
+	log_print("received message for the future, will queue it. expected seq: %u, message seq: %u, nodeid: %d",
+		  node->seq_next, seq, node->nodeid);
+
+	msg = dlm_recv_create_msg(p, seq);
+	if (!msg)
+		return -ENOMEM;
+
+	atomic_inc(&node->recv_queue_cnt);
+	list_add_tail(&msg->list, &node->recv_queue);
+
+	return 0;
+}
+
+static void dlm_recv_queue_lookup_and_deliver_next(struct midcomms_node *node)
+{
+	struct dlm_recv_msg *msg;
+
+	msg = dlm_recv_get_msg_by_seq(node, node->seq_next);
+	while (msg) {
+		list_del(&msg->list);
+
+		log_print("deliver message from the queue because it was received in the past. message seq: %u, nodeid: %d",
+			  node->seq_next, node->nodeid);
+		dlm_midcomms_seq_receive_buffer(node, msg->p);
+
+		if (atomic_dec_and_test(&node->recv_queue_cnt))
+			wake_up(&node->fin_wait);
+
+		kfree(msg->p);
+		kfree(msg);
+
+		msg = dlm_recv_get_msg_by_seq(node, node->seq_next);
+	}
+}
+
+static void dlm_midcomms_receive_buffer(union dlm_packet *p,
+					struct midcomms_node *node,
+					uint32_t seq)
+{
+	if (seq == node->seq_next) {
+		/* case when we received the expected next message */
+		dlm_midcomms_seq_receive_buffer(node, p);
+
+		/* lookup if we have the next message in the queue beceause
+		 * we might got some message for the future in the past as
+		 * we dropped some message which arrived now.
+		 */
+		dlm_recv_queue_lookup_and_deliver_next(node);
+	} else if (seq > node->seq_next) {
+		/* We got some message in the future, we will queue it so
+		 * we can deliver the message when the next message arrived.
+		 */
+		dlm_recv_queue_future_msg(node, p, seq);
+	} else {
+		log_print("ignore message because it was already delivered. message seq: %u, expected: %u, nodeid: %d",
+			  seq, node->seq_next, node->nodeid);
+	}
+
+	dlm_send_ack(node->nodeid, node->seq_next);
+}
+
+static struct midcomms_node *
+dlm_midcomms_recv_node_lookup(int nodeid, const union dlm_packet *p,
+			      uint16_t msglen, int (*cb)(struct midcomms_node *node))
+{
+	struct midcomms_node *node;
+	gfp_t allocation = 0;
+	int ret;
+
+	switch (p->header.h_cmd) {
+	case DLM_RCOM:
+		if (msglen < sizeof(struct dlm_rcom)) {
+			log_print("rcom msg too small: %u, will skip this message from node %d",
+				  msglen, nodeid);
+			return NULL;
+		}
+
+		switch (le32_to_cpu(p->rcom.rc_type)) {
+		case DLM_RCOM_NAMES:
+			fallthrough;
+		case DLM_RCOM_NAMES_REPLY:
+			fallthrough;
+		case DLM_RCOM_STATUS:
+			fallthrough;
+		case DLM_RCOM_STATUS_REPLY:
+			allocation = GFP_NOFS;
+			break;
+		default:
+			break;
+		}
+
+		break;
+	default:
+		break;
+	}
+
+	node = nodeid2node(nodeid, allocation);
+	if (!node) {
+		switch (p->header.h_cmd) {
+		case DLM_OPTS:
+			if (msglen < sizeof(struct dlm_opts)) {
+				log_print("opts msg too small: %u, will skip this message from node %d",
+					  msglen, nodeid);
+				return NULL;
+			}
+
+			/* we only alloc a new node@receiving for the above
+			 * RCOM messages. It can be that the other side is
+			 * already gone and we cannot ack FIN messages anymore,
+			 * we ignore it until the other side runs into an
+			 * timeout. FIN messages are application stateless and
+			 * it's not imortant to be acked since it is the last
+			 * message before disconnect.
+			 *
+			 * we don't print a warning in this case.
+			 */
+			switch (p->opts.o_nextcmd) {
+			case DLM_FIN:
+				return NULL;
+			default:
+				break;
+			}
+
+			break;
+		default:
+			break;
+		}
+
+		log_print("received dlm message cmd %d from node %d in an invalid sequence",
+			  p->header.h_cmd, nodeid);
+		return NULL;
+	}
+
+	ret = cb(node);
+	if (ret < 0)
+		return NULL;
+
+	return node;
+}
+
+static int dlm_midcomms_version_check_3_2(struct midcomms_node *node)
+{
+	switch (node->version) {
+	case DLM_VERSION_NOT_SET:
+		node->version = DLM_VERSION_3_2;
+		log_print("version 0x%08x for node %d detected", DLM_VERSION_3_2,
+			  node->nodeid);
+		break;
+	case DLM_VERSION_3_2:
+		break;
+	default:
+		log_print("version mismatch detected, assumed 0x%08x but node %d has 0x%08x",
+			  DLM_VERSION_3_2, node->nodeid, node->version);
+		return -1;
+	}
+
+	return 0;
+}
+
+#if 0
+static int dlm_parse_opts(void *opts, uint16_t optlen)
+{
+	struct dlm_opt_header *hd;
+	void *ptr = opts;
+	uint16_t length;
+
+	while (optlen > 0) {
+		hd = ptr;
+		switch (le16_to_cpu(hd->t_type)) {
+		/* add options here */
+		default:
+			break;
+		}
+
+		length = le16_to_cpu(hd->t_length);
+		ptr += length;
+		optlen -= length;
+	}
+
+	return 0;
+}
+#endif
+
+static int dlm_opts_check_msglen(union dlm_packet *p, uint16_t msglen, int nodeid)
+{
+	/* we only trust outer header msglen because
+	 * it's checked against receive buffer length.
+	 */
+	if (msglen < sizeof(struct dlm_opts))
+		return -1;
+	msglen -= sizeof(struct dlm_opts);
+
+	if (msglen < le16_to_cpu(p->opts.o_optlen))
+		return -1;
+	msglen -= le16_to_cpu(p->opts.o_optlen);
+
+	switch (p->opts.o_nextcmd) {
+	case DLM_FIN:
+		if (msglen < sizeof(struct dlm_header)) {
+			log_print("fin too small: %u, will skip this message from node %d",
+				  msglen, nodeid);
+			return -1;
+		}
+
+		break;
+	case DLM_MSG:
+		if (msglen < sizeof(struct dlm_message)) {
+			log_print("msg too small: %u, will skip this message from node %d",
+				  msglen, nodeid);
+			return -1;
+		}
+
+		break;
+	case DLM_RCOM:
+		if (msglen < sizeof(struct dlm_rcom)) {
+			log_print("rcom msg too small: %u, will skip this message from node %d",
+				  msglen, nodeid);
+			return -1;
+		}
+
+		break;
+	default:
+		log_print("unsupported o_nextcmd received: %u, will skip this message from node %d",
+			  p->opts.o_nextcmd, nodeid);
+		return -1;
+	}
+
+	return 0;
+}
+
+static void dlm_midcomms_receive_buffer_3_2(union dlm_packet *p, int nodeid)
+{
+	uint16_t msglen = le16_to_cpu(p->header.h_length);
+	struct midcomms_node *node;
+	uint32_t seq;
+	int ret;
+
+	node = dlm_midcomms_recv_node_lookup(nodeid, p, msglen,
+					     dlm_midcomms_version_check_3_2);
+	if (!node)
+		return;
+
+	switch (p->header.h_cmd) {
+	case DLM_RCOM:
+		/* these rcom message we use to determine version.
+		 * they have their own retransmission handling and
+		 * are the first messages of dlm.
+		 *
+		 * length already checked.
+		 */
+		switch (le32_to_cpu(p->rcom.rc_type)) {
+		case DLM_RCOM_NAMES:
+			fallthrough;
+		case DLM_RCOM_NAMES_REPLY:
+			fallthrough;
+		case DLM_RCOM_STATUS:
+			fallthrough;
+		case DLM_RCOM_STATUS_REPLY:
+			break;
+		default:
+			log_print("unsupported rcom type received: %u, will skip this message from node %d",
+				  le32_to_cpu(p->rcom.rc_type), nodeid);
+			return;
+		}
+
+		dlm_receive_buffer(p, nodeid);
+		return;
+	case DLM_OPTS:
+		seq = le32_to_cpu(p->header.u.h_seq);
+
+		ret = dlm_opts_check_msglen(p, msglen, nodeid);
+		if (ret < 0) {
+			log_print("opts msg too small: %u, will skip this message from node %d",
+				  msglen, nodeid);
+			return;
+		}
+#if 0
+		ret = dlm_parse_opts(p->opts.o_opts, p->opts.o_optlen);
+		if (ret < 0)
+			return;
+#endif
+
+		p = (union dlm_packet *)((unsigned char *)p->opts.o_opts +
+					 le16_to_cpu(p->opts.o_optlen));
+
+		/* recheck inner msglen just if it's not garbage */
+		msglen = le16_to_cpu(p->header.h_length);
+		switch (p->header.h_cmd) {
+		case DLM_RCOM:
+			if (msglen < sizeof(struct dlm_rcom)) {
+				log_print("inner rcom msg too small: %u, will skip this message from node %d",
+					  msglen, nodeid);
+				return;
+			}
+
+			break;
+		case DLM_MSG:
+			if (msglen < sizeof(struct dlm_message)) {
+				log_print("inner msg too small: %u, will skip this message from node %d",
+					  msglen, nodeid);
+				return;
+			}
+
+			break;
+		case DLM_FIN:
+			if (msglen < sizeof(struct dlm_header)) {
+				log_print("inner fin too small: %u, will skip this message from node %d",
+					  msglen, nodeid);
+				return;
+			}
+
+			if (seq != node->seq_next) {
+				dlm_send_ack(nodeid, node->seq_next);
+				return;
+			}
+
+			dlm_send_ack(nodeid, seq + 1);
+			set_bit(DLM_NODE_FLAG_FIN, &node->flags);
+			wake_up(&node->fin_wait);
+			return;
+		default:
+			log_print("unsupported inner h_cmd received: %u, will skip this message from node %d",
+				  msglen, nodeid);
+			return;
+		}
+
+		dlm_midcomms_receive_buffer(p, node, seq);
+		return;
+	case DLM_ACK:
+		seq = le32_to_cpu(p->header.u.h_seq);
+		dlm_receive_ack(node, seq);
+		return;
+	default:
+		log_print("unsupported h_cmd received: %u, will skip this message from node %d",
+			  p->header.h_cmd, nodeid);
+		return;
+	}
+}
+
+static int dlm_midcomms_version_check_3_1(struct midcomms_node *node)
+{
+	switch (node->version) {
+	case DLM_VERSION_NOT_SET:
+		node->version = DLM_VERSION_3_1;
+		log_print("version 0x%08x for node %d detected", DLM_VERSION_3_1,
+			  node->nodeid);
+		break;
+	case DLM_VERSION_3_1:
+		break;
+	default:
+		log_print("version mismatch detected, assumed 0x%08x but node %d has 0x%08x",
+			  DLM_VERSION_3_1, node->nodeid, node->version);
+		return -1;
+	}
+
+	return 0;
+}
+
+static void dlm_midcomms_receive_buffer_3_1(union dlm_packet *p, int nodeid)
+{
+	uint16_t msglen = le16_to_cpu(p->header.h_length);
+	struct midcomms_node *node;
+
+	node = dlm_midcomms_recv_node_lookup(nodeid, p, msglen,
+					     dlm_midcomms_version_check_3_1);
+	if (!node)
+		return;
+
+	switch (p->header.h_cmd) {
+	case DLM_RCOM:
+		/* length already checked */
+		break;
+	case DLM_MSG:
+		if (msglen < sizeof(struct dlm_message)) {
+			log_print("msg too small: %u, will skip this message from node %d",
+				  msglen, nodeid);
+			return;
+		}
+
+		break;
+	default:
+		log_print("unsupported h_cmd received: %u, will skip this message from node %d",
+			  p->header.h_cmd, nodeid);
+		return;
+	}
+
+	dlm_receive_buffer(p, nodeid);
 }
 
 /*
@@ -89,7 +866,7 @@ int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
 	int ret = 0;
 
 	while (len >= sizeof(struct dlm_header)) {
-		hd = (struct dlm_header *)ptr;
+		hd = (const struct dlm_header *)ptr;
 
 		/* no message should be more than DEFAULT_BUFFER_SIZE or
 		 * less than dlm_header size.
@@ -116,32 +893,19 @@ int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
 		if (msglen > len)
 			break;
 
-		switch (hd->h_cmd) {
-		case DLM_MSG:
-			if (msglen < sizeof(struct dlm_message)) {
-				log_print("dlm msg too small: %u, will skip this message",
-					  msglen);
-				goto skip;
-			}
-
+		switch (le32_to_cpu(hd->h_version)) {
+		case DLM_VERSION_3_1:
+			dlm_midcomms_receive_buffer_3_1((union dlm_packet *)ptr, nodeid);
 			break;
-		case DLM_RCOM:
-			if (msglen < sizeof(struct dlm_rcom)) {
-				log_print("dlm rcom msg too small: %u, will skip this message",
-					  msglen);
-				goto skip;
-			}
-
+		case DLM_VERSION_3_2:
+			dlm_midcomms_receive_buffer_3_2((union dlm_packet *)ptr, nodeid);
 			break;
 		default:
-			log_print("unsupported h_cmd received: %u, will skip this message",
-				  hd->h_cmd);
-			goto skip;
+			log_print("received invalid version header: %u from node %d, will skip this message",
+				  le32_to_cpu(hd->h_version), nodeid);
+			break;
 		}
 
-		dlm_receive_buffer((union dlm_packet *)buf, nodeid);
-
-skip:
 		ret += msglen;
 		len -= msglen;
 		ptr += msglen;
@@ -149,3 +913,371 @@ int dlm_process_incoming_buffer(int nodeid, unsigned char *buf, int len)
 
 	return ret;
 }
+
+void *dlm_midcomms_stateless_get_buffer(int nodeid, int len, gfp_t allocation,
+					char **ppc)
+{
+	return dlm_lowcomms_new_buffer(nodeid, len, allocation,
+				       ppc, NULL, NULL);
+}
+
+void dlm_midcomms_stateless_commit_buffer(void *mh)
+{
+	dlm_lowcomms_commit_buffer(mh);
+	dlm_lowcomms_put_buffer(mh);
+}
+
+static void dlm_fill_opts_header(struct dlm_opts *opts, uint16_t inner_len,
+				 uint32_t seq)
+{
+	opts->o_header.h_cmd = DLM_OPTS;
+	opts->o_header.h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
+	opts->o_header.h_nodeid = dlm_our_nodeid();
+	opts->o_header.h_length = DLM_MIDCOMMS_OPT_LEN + inner_len;
+	opts->o_header.u.h_seq = seq;
+	header_out(&opts->o_header);
+}
+
+static void midcomms_get_buffer_cb(void *buf, void *priv)
+{
+	struct dlm_send_msg *msg = priv;
+
+	msg->seq = msg->node->seq_send++;
+}
+
+static void *dlm_midcomms_get_buffer_3_2(struct dlm_send_msg *msg, int nodeid,
+					 int len, gfp_t allocation, char **ppc)
+{
+	struct dlm_opts *opts;
+	void *mh;
+
+	mh = dlm_lowcomms_new_buffer(nodeid, len + DLM_MIDCOMMS_OPT_LEN,
+				     allocation, ppc, midcomms_get_buffer_cb, msg);
+	if (!mh)
+		return NULL;
+
+	opts = (struct dlm_opts *)*ppc;
+	msg->opts = opts;
+
+	/* add possible options here */
+	dlm_fill_opts_header(opts, len, msg->seq);
+
+	*ppc += sizeof(*opts);
+	msg->inner_hd = (const struct dlm_header *)*ppc;
+	return mh;
+}
+
+void *dlm_midcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
+{
+	struct midcomms_node *node;
+	struct dlm_send_msg *msg;
+	void *mh;
+
+	node = nodeid2node(nodeid, 0);
+	if (!node) {
+		WARN_ON_ONCE(1);
+		return NULL;
+	}
+
+	msg = kzalloc(sizeof(*msg), GFP_NOFS);
+	if (!msg)
+		return NULL;
+
+	msg->node = node;
+
+	switch (node->version) {
+	case DLM_VERSION_3_1:
+		mh = dlm_midcomms_stateless_get_buffer(nodeid, len, allocation,
+						       ppc);
+		if (!mh) {
+			kfree(msg);
+			return NULL;
+		}
+
+		break;
+	case DLM_VERSION_3_2:
+		mh = dlm_midcomms_get_buffer_3_2(msg, nodeid, len, allocation,
+						 ppc);
+		if (!mh) {
+			kfree(msg);
+			return NULL;
+		}
+
+		break;
+	default:
+		kfree(msg);
+		WARN_ON(1);
+		return NULL;
+	}
+
+	msg->mh = mh;
+
+	return msg;
+}
+
+static void dlm_midcomms_commit_buffer_3_2(struct dlm_send_msg *msg,
+					   struct midcomms_node *node)
+{
+	atomic_inc(&node->send_queue_cnt);
+
+	/* nexthdr chain for fast lookup */
+	msg->opts->o_nextcmd = msg->inner_hd->h_cmd;
+
+	/* required to set before list_add because timer */
+	msg->timeout = jiffies + DLM_RTO;
+
+	spin_lock(&node->send_queue_lock);
+	list_add_tail_rcu(&msg->list, &node->send_queue);
+	spin_unlock(&node->send_queue_lock);
+
+	dlm_lowcomms_commit_buffer(msg->mh);
+}
+
+static void dlm_midcomms_commit_buffer_3_1(void *mh)
+{
+	dlm_midcomms_stateless_commit_buffer(mh);
+}
+
+void dlm_midcomms_commit_buffer(void *mh)
+{
+	struct dlm_send_msg *msg = mh;
+
+	switch (msg->node->version) {
+	case DLM_VERSION_3_1:
+		dlm_midcomms_commit_buffer_3_1(msg->mh);
+		/* msg is not part of rcu list in this case */
+		kfree(msg);
+		break;
+	case DLM_VERSION_3_2:
+		dlm_midcomms_commit_buffer_3_2(msg, msg->node);
+		break;
+	default:
+		WARN_ON(1);
+		break;
+	}
+}
+
+void midcomms_add_member(int nodeid)
+{
+	struct midcomms_node *node;
+
+	if (nodeid == dlm_our_nodeid())
+		return;
+
+	node = nodeid2node(nodeid, GFP_NOFS);
+	if (!node)
+		return;
+
+	node->users++;
+}
+
+static void midcomms_drain_and_fin(struct midcomms_node *node)
+{
+	int ret;
+
+	/* old protocol, we don't wait for pending operations */
+	if (node->version == DLM_VERSION_3_1)
+		return;
+
+	/* wait until dlm is done */
+	ret = wait_event_timeout(node->fin_wait,
+				 (!atomic_read(&node->send_queue_cnt) &&
+				  !atomic_read(&node->recv_queue_cnt)) ||
+				 test_bit(DLM_NODE_FLAG_CLOSE, &node->flags),
+				 DLM_QUEUE_TIMEOUT);
+	if (!ret)
+		log_print("queues timed out from node %d", node->nodeid);
+
+	if (DLM_DEBUG_FENCE_TERMINATION)
+		msleep(5000);
+
+	/* send to other side we are done with dlm */
+	dlm_send_fin(node->nodeid);
+
+	/* still be able to receive and wait for other end dlm done */
+	ret = wait_event_timeout(node->fin_wait,
+				 (!atomic_read(&node->send_queue_cnt) &&
+				  !atomic_read(&node->recv_queue_cnt) &&
+				  test_bit(DLM_NODE_FLAG_FIN, &node->flags)) ||
+				 test_bit(DLM_NODE_FLAG_CLOSE, &node->flags),
+				 DLM_FIN_TIMEOUT);
+
+	/* if other side not response anymore flush everything
+	 * this has something to do with the FIN message and
+	 * we might didn't received an ACK because drops.
+	 */
+	if (!ret || test_bit(DLM_NODE_FLAG_CLOSE, &node->flags)) {
+		log_print("fin timed out from node %d", node->nodeid);
+		dlm_send_queue_flush(node);
+		synchronize_rcu();
+
+		dlm_recv_queue_flush(node);
+	}
+}
+
+static void midcomms_node_release(struct rcu_head *rcu)
+{
+	struct midcomms_node *node = container_of(rcu, struct midcomms_node, rcu);
+
+	kfree(node);
+}
+
+void midcomms_remove_member(int nodeid)
+{
+	struct midcomms_node *node;
+
+	if (nodeid == dlm_our_nodeid())
+		return;
+
+	mutex_lock(&close_lock);
+	node = nodeid2node(nodeid, 0);
+	if (!node) {
+		mutex_unlock(&close_lock);
+		return;
+	}
+
+	node->users--;
+
+	/* hitting users count to zero means the
+	 * other side is running dlm_midcomms_stop()
+	 * we meet us to have a clean disconnect.
+	 */
+	if (!node->users) {
+		midcomms_drain_and_fin(node);
+
+		spin_lock(&nodes_lock);
+		hlist_del_rcu(&node->hlist);
+		spin_unlock(&nodes_lock);
+
+		call_srcu(&nodes_srcu, &node->rcu, midcomms_node_release);
+	}
+	mutex_unlock(&close_lock);
+}
+
+static void dlm_retransmit_timer_expires(struct timer_list *timer)
+{
+
+	unsigned long now = jiffies;
+	struct midcomms_node *node;
+	struct dlm_send_msg *msg;
+	int idx, i;
+
+	rcu_read_lock();
+	idx = srcu_read_lock(&nodes_srcu);
+	for (i = 0; i < CONN_HASH_SIZE; i++) {
+		hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
+			list_for_each_entry_rcu(msg, &node->send_queue, list) {
+				if (time_before_eq(msg->timeout, now)) {
+					log_print("retransmit because ack timeout. message seq %u, nodeid %d",
+						  msg->seq, node->nodeid);
+
+					dlm_lowcomms_resend_buffer(msg->mh);
+				}
+			}
+		}
+	}
+	srcu_read_unlock(&nodes_srcu, idx);
+	rcu_read_unlock();
+
+	mod_timer(timer, jiffies + DLM_RTO_TIMER);
+}
+
+int dlm_midcomms_start(void)
+{
+	int i, ret;
+
+	for (i = 0; i < CONN_HASH_SIZE; i++)
+		INIT_HLIST_HEAD(&node_hash[i]);
+
+	ret = dlm_lowcomms_start();
+	if (ret == 0) {
+		timer_setup(&dlm_retransmit_timer,
+			    dlm_retransmit_timer_expires, TIMER_DEFERRABLE);
+		mod_timer(&dlm_retransmit_timer,
+			  jiffies + DLM_RTO_TIMER);
+	}
+
+	return ret;
+}
+
+void dlm_midcomms_stop(void)
+{
+	struct midcomms_node *node;
+	int i, idx;
+
+	mutex_lock(&close_lock);
+	idx = srcu_read_lock(&nodes_srcu);
+	for (i = 0; i < CONN_HASH_SIZE; i++) {
+		hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
+			midcomms_drain_and_fin(node);
+		}
+	}
+
+	del_timer_sync(&dlm_retransmit_timer);
+	dlm_lowcomms_stop();
+
+	for (i = 0; i < CONN_HASH_SIZE; i++) {
+		hlist_for_each_entry_rcu(node, &node_hash[i], hlist) {
+			spin_lock(&nodes_lock);
+			hlist_del_rcu(&node->hlist);
+			spin_unlock(&nodes_lock);
+
+			call_srcu(&nodes_srcu, &node->rcu, midcomms_node_release);
+		}
+	}
+	srcu_read_unlock(&nodes_srcu, idx);
+	mutex_unlock(&close_lock);
+}
+
+int dlm_midcomms_close(int nodeid)
+{
+	struct midcomms_node *node;
+	int ret, idx;
+
+	if (nodeid == dlm_our_nodeid())
+		return 0;
+
+	/* keep nodes_srcu read lock to prevent node is released, because
+	 * close can occur any time and we can't hold the close_lock.
+	 */
+	idx = srcu_read_lock(&nodes_srcu);
+	/* Abort pending close/remove operation */
+	node = nodeid2node(nodeid, 0);
+	if (node) {
+		set_bit(DLM_NODE_FLAG_CLOSE, &node->flags);
+		wake_up(&node->fin_wait);
+	}
+	srcu_read_unlock(&nodes_srcu, idx);
+
+	mutex_lock(&close_lock);
+	node = nodeid2node(nodeid, 0);
+	if (!node) {
+		mutex_unlock(&close_lock);
+		return dlm_lowcomms_close(nodeid);
+	}
+
+	dlm_lowcomms_rx_flush(nodeid);
+
+	spin_lock(&nodes_lock);
+	hlist_del_rcu(&node->hlist);
+	spin_unlock(&nodes_lock);
+
+	/* wait until there are all readers left */
+	synchronize_srcu(&nodes_srcu);
+
+	ret = dlm_lowcomms_close(nodeid);
+
+	/* cut current queues for 3.2 */
+	if (node->version == DLM_VERSION_3_2) {
+		dlm_send_queue_flush(node);
+		synchronize_rcu();
+
+		dlm_recv_queue_flush(node);
+	}
+
+	mutex_unlock(&close_lock);
+
+	call_srcu(&nodes_srcu, &node->rcu, midcomms_node_release);
+
+	return ret;
+}
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 18/20] fs: dlm: don't allow half transmitted messages

[Alexander Aring]

This patch will clean a dirty page buffer if a reconnect occurs. If a page
buffer was half transmitted we cannot start inside the middle of a dlm
message if a node connects again. I observed invalid length receptions
errors and was guessing that this behaviour occurs, after this patch I
never saw an invalid message length again. This patch might drops more
messages for dlm version 3.1 but 3.1 can't deal with half messages as
well, for 3.2 it might trigger more re-transmissions but will not leave dlm
in a broken state.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/lowcomms.c | 84 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 54 insertions(+), 30 deletions(-)

diff --git a/fs/dlm/lowcomms.c b/fs/dlm/lowcomms.c
index 0e4cbabc680f..44a34becb780 100644
--- a/fs/dlm/lowcomms.c
+++ b/fs/dlm/lowcomms.c
@@ -112,6 +112,7 @@ struct writequeue_entry {
 	int len;
 	int end;
 	int users;
+	bool dirty;
 	struct connection *con;
 	struct list_head msgs;
 	struct kref ref;
@@ -647,6 +648,36 @@ static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
 	memset((char *)saddr + *addr_len, 0, sizeof(struct sockaddr_storage) - *addr_len);
 }
 
+static void dlm_page_release(struct kref *kref)
+{
+	struct writequeue_entry *e = container_of(kref, struct writequeue_entry,
+						  ref);
+
+	__free_page(e->page);
+	kfree(e);
+}
+
+static void dlm_msg_release(struct kref *kref)
+{
+	struct dlm_msg *msg = container_of(kref, struct dlm_msg, ref);
+
+	kref_put(&msg->entry->ref, dlm_page_release);
+	kfree(msg);
+}
+
+static void free_entry(struct writequeue_entry *e)
+{
+	struct dlm_msg *msg, *tmp;
+
+	list_for_each_entry_safe(msg, tmp, &e->msgs, list) {
+		list_del(&msg->list);
+		kref_put(&msg->ref, dlm_msg_release);
+	}
+
+	list_del(&e->list);
+	kref_put(&e->ref, dlm_page_release);
+}
+
 static void dlm_close_sock(struct socket **sock)
 {
 	if (*sock) {
@@ -661,6 +692,7 @@ static void close_connection(struct connection *con, bool and_other,
 			     bool tx, bool rx)
 {
 	bool closing = test_and_set_bit(CF_CLOSING, &con->flags);
+	struct writequeue_entry *e;
 
 	if (tx && !closing && cancel_work_sync(&con->swork)) {
 		log_print("canceled swork for node %d", con->nodeid);
@@ -679,6 +711,26 @@ static void close_connection(struct connection *con, bool and_other,
 		close_connection(con->othercon, false, true, true);
 	}
 
+	/* if we send a writequeue entry only a half way, we drop the
+	 * whole entry because reconnection and that we not start of the
+	 * middle of a msg which will confuse the other end.
+	 *
+	 * we can always drop messages because retransmits, but what we
+	 * cannot allow is to transmit half messages which may be processed
+	 * at the other side.
+	 *
+	 * our policy is to start on a clean state when disconnects, we don't
+	 * know what's send/received on transport layer in this case.
+	 */
+	spin_lock_bh(&con->writequeue_lock);
+	if (!list_empty(&con->writequeue)) {
+		e = list_first_entry(&con->writequeue, struct writequeue_entry,
+				     list);
+		if (e->dirty)
+			free_entry(e);
+	}
+	spin_unlock_bh(&con->writequeue_lock);
+
 	con->rx_leftover = 0;
 	con->retries = 0;
 	clear_bit(CF_CONNECTED, &con->flags);
@@ -958,36 +1010,6 @@ static int accept_from_sock(struct listen_connection *con)
 	return result;
 }
 
-static void dlm_page_release(struct kref *kref)
-{
-	struct writequeue_entry *e = container_of(kref, struct writequeue_entry,
-						  ref);
-
-	__free_page(e->page);
-	kfree(e);
-}
-
-static void dlm_msg_release(struct kref *kref)
-{
-	struct dlm_msg *msg = container_of(kref, struct dlm_msg, ref);
-
-	kref_put(&msg->entry->ref, dlm_page_release);
-	kfree(msg);
-}
-
-static void free_entry(struct writequeue_entry *e)
-{
-	struct dlm_msg *msg, *tmp;
-
-	list_for_each_entry_safe(msg, tmp, &e->msgs, list) {
-		list_del(&msg->list);
-		kref_put(&msg->ref, dlm_msg_release);
-	}
-
-	list_del(&e->list);
-	kref_put(&e->ref, dlm_page_release);
-}
-
 /*
  * writequeue_entry_complete - try to delete and free write queue entry
  * @e: write queue entry to try to delete
@@ -999,6 +1021,8 @@ static void writequeue_entry_complete(struct writequeue_entry *e, int completed)
 {
 	e->offset += completed;
 	e->len -= completed;
+	/* signal that page was half way transmitted */
+	e->dirty = true;
 
 	if (e->len == 0 && e->users == 0)
 		free_entry(e);
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 19/20] fs: dlm: remove obsolete code and comment

[Alexander Aring]

This patch removes obsolete macros and a comment. The macro was there
for temporary copy a dlm message on a stack buffer, nowadays we operate
directly on receive buffer which was given to the socket receive API.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/dlm_internal.h | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/fs/dlm/dlm_internal.h b/fs/dlm/dlm_internal.h
index da2297705713..a735f2816ef7 100644
--- a/fs/dlm/dlm_internal.h
+++ b/fs/dlm/dlm_internal.h
@@ -41,12 +41,6 @@
 #include <linux/dlm.h>
 #include "config.h"
 
-/* Size of the temp buffer midcomms allocates on the stack.
-   We try to make this large enough so most messages fit.
-   FIXME: should sctp make this unnecessary? */
-
-#define DLM_INBUF_LEN		148
-
 struct dlm_ls;
 struct dlm_lkb;
 struct dlm_rsb;
-- 
2.26.2

[Cluster-devel] [PATCHv4 dlm/next 20/20] fs: dlm: check for invalid namelen

[Alexander Aring]

This patch adds an additional check inside the dlm locking from user space
functionality that the namelen isn't above the maximum allowed dlm
resource name length. If the namelen is above the maximum allowed we
have a invalid state and out of buffer access can occur. Cut off the
namelen attribute to maximum size is not an option because we might run
into name conflicts and the user should be get aware of that.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 fs/dlm/user.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/dlm/user.c b/fs/dlm/user.c
index e5cefa90b1ce..9f2f743eeb31 100644
--- a/fs/dlm/user.c
+++ b/fs/dlm/user.c
@@ -241,6 +241,9 @@ static int device_user_lock(struct dlm_user_proc *proc,
 	uint32_t lkid;
 	int error = -ENOMEM;
 
+	if (params->namelen > DLM_RESNAME_MAXLEN)
+		return -EINVAL;
+
 	ls = dlm_find_lockspace_local(proc->lockspace);
 	if (!ls)
 		return -ENOENT;
-- 
2.26.2