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TOMOYO Linux Cross Reference
Linux/fs/dlm/lowcomms.c

Version: ~ [ linux-5.6 ] ~ [ linux-5.5.13 ] ~ [ linux-5.4.28 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.113 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.174 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.217 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.217 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.82 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /******************************************************************************
  2 *******************************************************************************
  3 **
  4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
  5 **  Copyright (C) 2004-2009 Red Hat, Inc.  All rights reserved.
  6 **
  7 **  This copyrighted material is made available to anyone wishing to use,
  8 **  modify, copy, or redistribute it subject to the terms and conditions
  9 **  of the GNU General Public License v.2.
 10 **
 11 *******************************************************************************
 12 ******************************************************************************/
 13 
 14 /*
 15  * lowcomms.c
 16  *
 17  * This is the "low-level" comms layer.
 18  *
 19  * It is responsible for sending/receiving messages
 20  * from other nodes in the cluster.
 21  *
 22  * Cluster nodes are referred to by their nodeids. nodeids are
 23  * simply 32 bit numbers to the locking module - if they need to
 24  * be expanded for the cluster infrastructure then that is its
 25  * responsibility. It is this layer's
 26  * responsibility to resolve these into IP address or
 27  * whatever it needs for inter-node communication.
 28  *
 29  * The comms level is two kernel threads that deal mainly with
 30  * the receiving of messages from other nodes and passing them
 31  * up to the mid-level comms layer (which understands the
 32  * message format) for execution by the locking core, and
 33  * a send thread which does all the setting up of connections
 34  * to remote nodes and the sending of data. Threads are not allowed
 35  * to send their own data because it may cause them to wait in times
 36  * of high load. Also, this way, the sending thread can collect together
 37  * messages bound for one node and send them in one block.
 38  *
 39  * lowcomms will choose to use either TCP or SCTP as its transport layer
 40  * depending on the configuration variable 'protocol'. This should be set
 41  * to 0 (default) for TCP or 1 for SCTP. It should be configured using a
 42  * cluster-wide mechanism as it must be the same on all nodes of the cluster
 43  * for the DLM to function.
 44  *
 45  */
 46 
 47 #include <asm/ioctls.h>
 48 #include <net/sock.h>
 49 #include <net/tcp.h>
 50 #include <linux/pagemap.h>
 51 #include <linux/file.h>
 52 #include <linux/mutex.h>
 53 #include <linux/sctp.h>
 54 #include <linux/slab.h>
 55 #include <net/sctp/sctp.h>
 56 #include <net/ipv6.h>
 57 
 58 #include "dlm_internal.h"
 59 #include "lowcomms.h"
 60 #include "midcomms.h"
 61 #include "config.h"
 62 
 63 #define NEEDED_RMEM (4*1024*1024)
 64 #define CONN_HASH_SIZE 32
 65 
 66 /* Number of messages to send before rescheduling */
 67 #define MAX_SEND_MSG_COUNT 25
 68 
 69 struct cbuf {
 70         unsigned int base;
 71         unsigned int len;
 72         unsigned int mask;
 73 };
 74 
 75 static void cbuf_add(struct cbuf *cb, int n)
 76 {
 77         cb->len += n;
 78 }
 79 
 80 static int cbuf_data(struct cbuf *cb)
 81 {
 82         return ((cb->base + cb->len) & cb->mask);
 83 }
 84 
 85 static void cbuf_init(struct cbuf *cb, int size)
 86 {
 87         cb->base = cb->len = 0;
 88         cb->mask = size-1;
 89 }
 90 
 91 static void cbuf_eat(struct cbuf *cb, int n)
 92 {
 93         cb->len  -= n;
 94         cb->base += n;
 95         cb->base &= cb->mask;
 96 }
 97 
 98 static bool cbuf_empty(struct cbuf *cb)
 99 {
100         return cb->len == 0;
101 }
102 
103 struct connection {
104         struct socket *sock;    /* NULL if not connected */
105         uint32_t nodeid;        /* So we know who we are in the list */
106         struct mutex sock_mutex;
107         unsigned long flags;
108 #define CF_READ_PENDING 1
109 #define CF_WRITE_PENDING 2
110 #define CF_CONNECT_PENDING 3
111 #define CF_INIT_PENDING 4
112 #define CF_IS_OTHERCON 5
113 #define CF_CLOSE 6
114 #define CF_APP_LIMITED 7
115         struct list_head writequeue;  /* List of outgoing writequeue_entries */
116         spinlock_t writequeue_lock;
117         int (*rx_action) (struct connection *); /* What to do when active */
118         void (*connect_action) (struct connection *);   /* What to do to connect */
119         struct page *rx_page;
120         struct cbuf cb;
121         int retries;
122 #define MAX_CONNECT_RETRIES 3
123         struct hlist_node list;
124         struct connection *othercon;
125         struct work_struct rwork; /* Receive workqueue */
126         struct work_struct swork; /* Send workqueue */
127         void (*orig_error_report)(struct sock *);
128         void (*orig_data_ready)(struct sock *);
129         void (*orig_state_change)(struct sock *);
130         void (*orig_write_space)(struct sock *);
131 };
132 #define sock2con(x) ((struct connection *)(x)->sk_user_data)
133 
134 /* An entry waiting to be sent */
135 struct writequeue_entry {
136         struct list_head list;
137         struct page *page;
138         int offset;
139         int len;
140         int end;
141         int users;
142         struct connection *con;
143 };
144 
145 struct dlm_node_addr {
146         struct list_head list;
147         int nodeid;
148         int addr_count;
149         int curr_addr_index;
150         struct sockaddr_storage *addr[DLM_MAX_ADDR_COUNT];
151 };
152 
153 static LIST_HEAD(dlm_node_addrs);
154 static DEFINE_SPINLOCK(dlm_node_addrs_spin);
155 
156 static struct sockaddr_storage *dlm_local_addr[DLM_MAX_ADDR_COUNT];
157 static int dlm_local_count;
158 static int dlm_allow_conn;
159 
160 /* Work queues */
161 static struct workqueue_struct *recv_workqueue;
162 static struct workqueue_struct *send_workqueue;
163 
164 static struct hlist_head connection_hash[CONN_HASH_SIZE];
165 static DEFINE_MUTEX(connections_lock);
166 static struct kmem_cache *con_cache;
167 
168 static void process_recv_sockets(struct work_struct *work);
169 static void process_send_sockets(struct work_struct *work);
170 
171 
172 /* This is deliberately very simple because most clusters have simple
173    sequential nodeids, so we should be able to go straight to a connection
174    struct in the array */
175 static inline int nodeid_hash(int nodeid)
176 {
177         return nodeid & (CONN_HASH_SIZE-1);
178 }
179 
180 static struct connection *__find_con(int nodeid)
181 {
182         int r;
183         struct connection *con;
184 
185         r = nodeid_hash(nodeid);
186 
187         hlist_for_each_entry(con, &connection_hash[r], list) {
188                 if (con->nodeid == nodeid)
189                         return con;
190         }
191         return NULL;
192 }
193 
194 /*
195  * If 'allocation' is zero then we don't attempt to create a new
196  * connection structure for this node.
197  */
198 static struct connection *__nodeid2con(int nodeid, gfp_t alloc)
199 {
200         struct connection *con = NULL;
201         int r;
202 
203         con = __find_con(nodeid);
204         if (con || !alloc)
205                 return con;
206 
207         con = kmem_cache_zalloc(con_cache, alloc);
208         if (!con)
209                 return NULL;
210 
211         r = nodeid_hash(nodeid);
212         hlist_add_head(&con->list, &connection_hash[r]);
213 
214         con->nodeid = nodeid;
215         mutex_init(&con->sock_mutex);
216         INIT_LIST_HEAD(&con->writequeue);
217         spin_lock_init(&con->writequeue_lock);
218         INIT_WORK(&con->swork, process_send_sockets);
219         INIT_WORK(&con->rwork, process_recv_sockets);
220 
221         /* Setup action pointers for child sockets */
222         if (con->nodeid) {
223                 struct connection *zerocon = __find_con(0);
224 
225                 con->connect_action = zerocon->connect_action;
226                 if (!con->rx_action)
227                         con->rx_action = zerocon->rx_action;
228         }
229 
230         return con;
231 }
232 
233 /* Loop round all connections */
234 static void foreach_conn(void (*conn_func)(struct connection *c))
235 {
236         int i;
237         struct hlist_node *n;
238         struct connection *con;
239 
240         for (i = 0; i < CONN_HASH_SIZE; i++) {
241                 hlist_for_each_entry_safe(con, n, &connection_hash[i], list)
242                         conn_func(con);
243         }
244 }
245 
246 static struct connection *nodeid2con(int nodeid, gfp_t allocation)
247 {
248         struct connection *con;
249 
250         mutex_lock(&connections_lock);
251         con = __nodeid2con(nodeid, allocation);
252         mutex_unlock(&connections_lock);
253 
254         return con;
255 }
256 
257 static struct dlm_node_addr *find_node_addr(int nodeid)
258 {
259         struct dlm_node_addr *na;
260 
261         list_for_each_entry(na, &dlm_node_addrs, list) {
262                 if (na->nodeid == nodeid)
263                         return na;
264         }
265         return NULL;
266 }
267 
268 static int addr_compare(struct sockaddr_storage *x, struct sockaddr_storage *y)
269 {
270         switch (x->ss_family) {
271         case AF_INET: {
272                 struct sockaddr_in *sinx = (struct sockaddr_in *)x;
273                 struct sockaddr_in *siny = (struct sockaddr_in *)y;
274                 if (sinx->sin_addr.s_addr != siny->sin_addr.s_addr)
275                         return 0;
276                 if (sinx->sin_port != siny->sin_port)
277                         return 0;
278                 break;
279         }
280         case AF_INET6: {
281                 struct sockaddr_in6 *sinx = (struct sockaddr_in6 *)x;
282                 struct sockaddr_in6 *siny = (struct sockaddr_in6 *)y;
283                 if (!ipv6_addr_equal(&sinx->sin6_addr, &siny->sin6_addr))
284                         return 0;
285                 if (sinx->sin6_port != siny->sin6_port)
286                         return 0;
287                 break;
288         }
289         default:
290                 return 0;
291         }
292         return 1;
293 }
294 
295 static int nodeid_to_addr(int nodeid, struct sockaddr_storage *sas_out,
296                           struct sockaddr *sa_out, bool try_new_addr)
297 {
298         struct sockaddr_storage sas;
299         struct dlm_node_addr *na;
300 
301         if (!dlm_local_count)
302                 return -1;
303 
304         spin_lock(&dlm_node_addrs_spin);
305         na = find_node_addr(nodeid);
306         if (na && na->addr_count) {
307                 memcpy(&sas, na->addr[na->curr_addr_index],
308                        sizeof(struct sockaddr_storage));
309 
310                 if (try_new_addr) {
311                         na->curr_addr_index++;
312                         if (na->curr_addr_index == na->addr_count)
313                                 na->curr_addr_index = 0;
314                 }
315         }
316         spin_unlock(&dlm_node_addrs_spin);
317 
318         if (!na)
319                 return -EEXIST;
320 
321         if (!na->addr_count)
322                 return -ENOENT;
323 
324         if (sas_out)
325                 memcpy(sas_out, &sas, sizeof(struct sockaddr_storage));
326 
327         if (!sa_out)
328                 return 0;
329 
330         if (dlm_local_addr[0]->ss_family == AF_INET) {
331                 struct sockaddr_in *in4  = (struct sockaddr_in *) &sas;
332                 struct sockaddr_in *ret4 = (struct sockaddr_in *) sa_out;
333                 ret4->sin_addr.s_addr = in4->sin_addr.s_addr;
334         } else {
335                 struct sockaddr_in6 *in6  = (struct sockaddr_in6 *) &sas;
336                 struct sockaddr_in6 *ret6 = (struct sockaddr_in6 *) sa_out;
337                 ret6->sin6_addr = in6->sin6_addr;
338         }
339 
340         return 0;
341 }
342 
343 static int addr_to_nodeid(struct sockaddr_storage *addr, int *nodeid)
344 {
345         struct dlm_node_addr *na;
346         int rv = -EEXIST;
347         int addr_i;
348 
349         spin_lock(&dlm_node_addrs_spin);
350         list_for_each_entry(na, &dlm_node_addrs, list) {
351                 if (!na->addr_count)
352                         continue;
353 
354                 for (addr_i = 0; addr_i < na->addr_count; addr_i++) {
355                         if (addr_compare(na->addr[addr_i], addr)) {
356                                 *nodeid = na->nodeid;
357                                 rv = 0;
358                                 goto unlock;
359                         }
360                 }
361         }
362 unlock:
363         spin_unlock(&dlm_node_addrs_spin);
364         return rv;
365 }
366 
367 int dlm_lowcomms_addr(int nodeid, struct sockaddr_storage *addr, int len)
368 {
369         struct sockaddr_storage *new_addr;
370         struct dlm_node_addr *new_node, *na;
371 
372         new_node = kzalloc(sizeof(struct dlm_node_addr), GFP_NOFS);
373         if (!new_node)
374                 return -ENOMEM;
375 
376         new_addr = kzalloc(sizeof(struct sockaddr_storage), GFP_NOFS);
377         if (!new_addr) {
378                 kfree(new_node);
379                 return -ENOMEM;
380         }
381 
382         memcpy(new_addr, addr, len);
383 
384         spin_lock(&dlm_node_addrs_spin);
385         na = find_node_addr(nodeid);
386         if (!na) {
387                 new_node->nodeid = nodeid;
388                 new_node->addr[0] = new_addr;
389                 new_node->addr_count = 1;
390                 list_add(&new_node->list, &dlm_node_addrs);
391                 spin_unlock(&dlm_node_addrs_spin);
392                 return 0;
393         }
394 
395         if (na->addr_count >= DLM_MAX_ADDR_COUNT) {
396                 spin_unlock(&dlm_node_addrs_spin);
397                 kfree(new_addr);
398                 kfree(new_node);
399                 return -ENOSPC;
400         }
401 
402         na->addr[na->addr_count++] = new_addr;
403         spin_unlock(&dlm_node_addrs_spin);
404         kfree(new_node);
405         return 0;
406 }
407 
408 /* Data available on socket or listen socket received a connect */
409 static void lowcomms_data_ready(struct sock *sk)
410 {
411         struct connection *con = sock2con(sk);
412         if (con && !test_and_set_bit(CF_READ_PENDING, &con->flags))
413                 queue_work(recv_workqueue, &con->rwork);
414 }
415 
416 static void lowcomms_write_space(struct sock *sk)
417 {
418         struct connection *con = sock2con(sk);
419 
420         if (!con)
421                 return;
422 
423         clear_bit(SOCK_NOSPACE, &con->sock->flags);
424 
425         if (test_and_clear_bit(CF_APP_LIMITED, &con->flags)) {
426                 con->sock->sk->sk_write_pending--;
427                 clear_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags);
428         }
429 
430         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags))
431                 queue_work(send_workqueue, &con->swork);
432 }
433 
434 static inline void lowcomms_connect_sock(struct connection *con)
435 {
436         if (test_bit(CF_CLOSE, &con->flags))
437                 return;
438         if (!test_and_set_bit(CF_CONNECT_PENDING, &con->flags))
439                 queue_work(send_workqueue, &con->swork);
440 }
441 
442 static void lowcomms_state_change(struct sock *sk)
443 {
444         /* SCTP layer is not calling sk_data_ready when the connection
445          * is done, so we catch the signal through here. Also, it
446          * doesn't switch socket state when entering shutdown, so we
447          * skip the write in that case.
448          */
449         if (sk->sk_shutdown) {
450                 if (sk->sk_shutdown == RCV_SHUTDOWN)
451                         lowcomms_data_ready(sk);
452         } else if (sk->sk_state == TCP_ESTABLISHED) {
453                 lowcomms_write_space(sk);
454         }
455 }
456 
457 int dlm_lowcomms_connect_node(int nodeid)
458 {
459         struct connection *con;
460 
461         if (nodeid == dlm_our_nodeid())
462                 return 0;
463 
464         con = nodeid2con(nodeid, GFP_NOFS);
465         if (!con)
466                 return -ENOMEM;
467         lowcomms_connect_sock(con);
468         return 0;
469 }
470 
471 static void lowcomms_error_report(struct sock *sk)
472 {
473         struct connection *con;
474         struct sockaddr_storage saddr;
475         int buflen;
476         void (*orig_report)(struct sock *) = NULL;
477 
478         read_lock_bh(&sk->sk_callback_lock);
479         con = sock2con(sk);
480         if (con == NULL)
481                 goto out;
482 
483         orig_report = con->orig_error_report;
484         if (con->sock == NULL ||
485             kernel_getpeername(con->sock, (struct sockaddr *)&saddr, &buflen)) {
486                 printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
487                                    "sending to node %d, port %d, "
488                                    "sk_err=%d/%d\n", dlm_our_nodeid(),
489                                    con->nodeid, dlm_config.ci_tcp_port,
490                                    sk->sk_err, sk->sk_err_soft);
491         } else if (saddr.ss_family == AF_INET) {
492                 struct sockaddr_in *sin4 = (struct sockaddr_in *)&saddr;
493 
494                 printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
495                                    "sending to node %d at %pI4, port %d, "
496                                    "sk_err=%d/%d\n", dlm_our_nodeid(),
497                                    con->nodeid, &sin4->sin_addr.s_addr,
498                                    dlm_config.ci_tcp_port, sk->sk_err,
499                                    sk->sk_err_soft);
500         } else {
501                 struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&saddr;
502 
503                 printk_ratelimited(KERN_ERR "dlm: node %d: socket error "
504                                    "sending to node %d at %u.%u.%u.%u, "
505                                    "port %d, sk_err=%d/%d\n", dlm_our_nodeid(),
506                                    con->nodeid, sin6->sin6_addr.s6_addr32[0],
507                                    sin6->sin6_addr.s6_addr32[1],
508                                    sin6->sin6_addr.s6_addr32[2],
509                                    sin6->sin6_addr.s6_addr32[3],
510                                    dlm_config.ci_tcp_port, sk->sk_err,
511                                    sk->sk_err_soft);
512         }
513 out:
514         read_unlock_bh(&sk->sk_callback_lock);
515         if (orig_report)
516                 orig_report(sk);
517 }
518 
519 /* Note: sk_callback_lock must be locked before calling this function. */
520 static void save_callbacks(struct connection *con, struct sock *sk)
521 {
522         lock_sock(sk);
523         con->orig_data_ready = sk->sk_data_ready;
524         con->orig_state_change = sk->sk_state_change;
525         con->orig_write_space = sk->sk_write_space;
526         con->orig_error_report = sk->sk_error_report;
527         release_sock(sk);
528 }
529 
530 static void restore_callbacks(struct connection *con, struct sock *sk)
531 {
532         write_lock_bh(&sk->sk_callback_lock);
533         lock_sock(sk);
534         sk->sk_user_data = NULL;
535         sk->sk_data_ready = con->orig_data_ready;
536         sk->sk_state_change = con->orig_state_change;
537         sk->sk_write_space = con->orig_write_space;
538         sk->sk_error_report = con->orig_error_report;
539         release_sock(sk);
540         write_unlock_bh(&sk->sk_callback_lock);
541 }
542 
543 /* Make a socket active */
544 static void add_sock(struct socket *sock, struct connection *con)
545 {
546         struct sock *sk = sock->sk;
547 
548         write_lock_bh(&sk->sk_callback_lock);
549         con->sock = sock;
550 
551         sk->sk_user_data = con;
552         if (!test_bit(CF_IS_OTHERCON, &con->flags))
553                 save_callbacks(con, sk);
554         /* Install a data_ready callback */
555         sk->sk_data_ready = lowcomms_data_ready;
556         sk->sk_write_space = lowcomms_write_space;
557         sk->sk_state_change = lowcomms_state_change;
558         sk->sk_allocation = GFP_NOFS;
559         sk->sk_error_report = lowcomms_error_report;
560         write_unlock_bh(&sk->sk_callback_lock);
561 }
562 
563 /* Add the port number to an IPv6 or 4 sockaddr and return the address
564    length */
565 static void make_sockaddr(struct sockaddr_storage *saddr, uint16_t port,
566                           int *addr_len)
567 {
568         saddr->ss_family =  dlm_local_addr[0]->ss_family;
569         if (saddr->ss_family == AF_INET) {
570                 struct sockaddr_in *in4_addr = (struct sockaddr_in *)saddr;
571                 in4_addr->sin_port = cpu_to_be16(port);
572                 *addr_len = sizeof(struct sockaddr_in);
573                 memset(&in4_addr->sin_zero, 0, sizeof(in4_addr->sin_zero));
574         } else {
575                 struct sockaddr_in6 *in6_addr = (struct sockaddr_in6 *)saddr;
576                 in6_addr->sin6_port = cpu_to_be16(port);
577                 *addr_len = sizeof(struct sockaddr_in6);
578         }
579         memset((char *)saddr + *addr_len, 0, sizeof(struct sockaddr_storage) - *addr_len);
580 }
581 
582 /* Close a remote connection and tidy up */
583 static void close_connection(struct connection *con, bool and_other,
584                              bool tx, bool rx)
585 {
586         clear_bit(CF_CONNECT_PENDING, &con->flags);
587         clear_bit(CF_WRITE_PENDING, &con->flags);
588         if (tx && cancel_work_sync(&con->swork))
589                 log_print("canceled swork for node %d", con->nodeid);
590         if (rx && cancel_work_sync(&con->rwork))
591                 log_print("canceled rwork for node %d", con->nodeid);
592 
593         mutex_lock(&con->sock_mutex);
594         if (con->sock) {
595                 if (!test_bit(CF_IS_OTHERCON, &con->flags))
596                         restore_callbacks(con, con->sock->sk);
597                 sock_release(con->sock);
598                 con->sock = NULL;
599         }
600         if (con->othercon && and_other) {
601                 /* Will only re-enter once. */
602                 close_connection(con->othercon, false, true, true);
603         }
604         if (con->rx_page) {
605                 __free_page(con->rx_page);
606                 con->rx_page = NULL;
607         }
608 
609         con->retries = 0;
610         mutex_unlock(&con->sock_mutex);
611 }
612 
613 /* Data received from remote end */
614 static int receive_from_sock(struct connection *con)
615 {
616         int ret = 0;
617         struct msghdr msg = {};
618         struct kvec iov[2];
619         unsigned len;
620         int r;
621         int call_again_soon = 0;
622         int nvec;
623 
624         mutex_lock(&con->sock_mutex);
625 
626         if (con->sock == NULL) {
627                 ret = -EAGAIN;
628                 goto out_close;
629         }
630         if (con->nodeid == 0) {
631                 ret = -EINVAL;
632                 goto out_close;
633         }
634 
635         if (con->rx_page == NULL) {
636                 /*
637                  * This doesn't need to be atomic, but I think it should
638                  * improve performance if it is.
639                  */
640                 con->rx_page = alloc_page(GFP_ATOMIC);
641                 if (con->rx_page == NULL)
642                         goto out_resched;
643                 cbuf_init(&con->cb, PAGE_SIZE);
644         }
645 
646         /*
647          * iov[0] is the bit of the circular buffer between the current end
648          * point (cb.base + cb.len) and the end of the buffer.
649          */
650         iov[0].iov_len = con->cb.base - cbuf_data(&con->cb);
651         iov[0].iov_base = page_address(con->rx_page) + cbuf_data(&con->cb);
652         iov[1].iov_len = 0;
653         nvec = 1;
654 
655         /*
656          * iov[1] is the bit of the circular buffer between the start of the
657          * buffer and the start of the currently used section (cb.base)
658          */
659         if (cbuf_data(&con->cb) >= con->cb.base) {
660                 iov[0].iov_len = PAGE_SIZE - cbuf_data(&con->cb);
661                 iov[1].iov_len = con->cb.base;
662                 iov[1].iov_base = page_address(con->rx_page);
663                 nvec = 2;
664         }
665         len = iov[0].iov_len + iov[1].iov_len;
666 
667         r = ret = kernel_recvmsg(con->sock, &msg, iov, nvec, len,
668                                MSG_DONTWAIT | MSG_NOSIGNAL);
669         if (ret <= 0)
670                 goto out_close;
671         else if (ret == len)
672                 call_again_soon = 1;
673 
674         cbuf_add(&con->cb, ret);
675         ret = dlm_process_incoming_buffer(con->nodeid,
676                                           page_address(con->rx_page),
677                                           con->cb.base, con->cb.len,
678                                           PAGE_SIZE);
679         if (ret == -EBADMSG) {
680                 log_print("lowcomms: addr=%p, base=%u, len=%u, read=%d",
681                           page_address(con->rx_page), con->cb.base,
682                           con->cb.len, r);
683         }
684         if (ret < 0)
685                 goto out_close;
686         cbuf_eat(&con->cb, ret);
687 
688         if (cbuf_empty(&con->cb) && !call_again_soon) {
689                 __free_page(con->rx_page);
690                 con->rx_page = NULL;
691         }
692 
693         if (call_again_soon)
694                 goto out_resched;
695         mutex_unlock(&con->sock_mutex);
696         return 0;
697 
698 out_resched:
699         if (!test_and_set_bit(CF_READ_PENDING, &con->flags))
700                 queue_work(recv_workqueue, &con->rwork);
701         mutex_unlock(&con->sock_mutex);
702         return -EAGAIN;
703 
704 out_close:
705         mutex_unlock(&con->sock_mutex);
706         if (ret != -EAGAIN) {
707                 close_connection(con, false, true, false);
708                 /* Reconnect when there is something to send */
709         }
710         /* Don't return success if we really got EOF */
711         if (ret == 0)
712                 ret = -EAGAIN;
713 
714         return ret;
715 }
716 
717 /* Listening socket is busy, accept a connection */
718 static int tcp_accept_from_sock(struct connection *con)
719 {
720         int result;
721         struct sockaddr_storage peeraddr;
722         struct socket *newsock;
723         int len;
724         int nodeid;
725         struct connection *newcon;
726         struct connection *addcon;
727 
728         mutex_lock(&connections_lock);
729         if (!dlm_allow_conn) {
730                 mutex_unlock(&connections_lock);
731                 return -1;
732         }
733         mutex_unlock(&connections_lock);
734 
735         memset(&peeraddr, 0, sizeof(peeraddr));
736         result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
737                                   SOCK_STREAM, IPPROTO_TCP, &newsock);
738         if (result < 0)
739                 return -ENOMEM;
740 
741         mutex_lock_nested(&con->sock_mutex, 0);
742 
743         result = -ENOTCONN;
744         if (con->sock == NULL)
745                 goto accept_err;
746 
747         newsock->type = con->sock->type;
748         newsock->ops = con->sock->ops;
749 
750         result = con->sock->ops->accept(con->sock, newsock, O_NONBLOCK);
751         if (result < 0)
752                 goto accept_err;
753 
754         /* Get the connected socket's peer */
755         memset(&peeraddr, 0, sizeof(peeraddr));
756         if (newsock->ops->getname(newsock, (struct sockaddr *)&peeraddr,
757                                   &len, 2)) {
758                 result = -ECONNABORTED;
759                 goto accept_err;
760         }
761 
762         /* Get the new node's NODEID */
763         make_sockaddr(&peeraddr, 0, &len);
764         if (addr_to_nodeid(&peeraddr, &nodeid)) {
765                 unsigned char *b=(unsigned char *)&peeraddr;
766                 log_print("connect from non cluster node");
767                 print_hex_dump_bytes("ss: ", DUMP_PREFIX_NONE, 
768                                      b, sizeof(struct sockaddr_storage));
769                 sock_release(newsock);
770                 mutex_unlock(&con->sock_mutex);
771                 return -1;
772         }
773 
774         log_print("got connection from %d", nodeid);
775 
776         /*  Check to see if we already have a connection to this node. This
777          *  could happen if the two nodes initiate a connection at roughly
778          *  the same time and the connections cross on the wire.
779          *  In this case we store the incoming one in "othercon"
780          */
781         newcon = nodeid2con(nodeid, GFP_NOFS);
782         if (!newcon) {
783                 result = -ENOMEM;
784                 goto accept_err;
785         }
786         mutex_lock_nested(&newcon->sock_mutex, 1);
787         if (newcon->sock) {
788                 struct connection *othercon = newcon->othercon;
789 
790                 if (!othercon) {
791                         othercon = kmem_cache_zalloc(con_cache, GFP_NOFS);
792                         if (!othercon) {
793                                 log_print("failed to allocate incoming socket");
794                                 mutex_unlock(&newcon->sock_mutex);
795                                 result = -ENOMEM;
796                                 goto accept_err;
797                         }
798                         othercon->nodeid = nodeid;
799                         othercon->rx_action = receive_from_sock;
800                         mutex_init(&othercon->sock_mutex);
801                         INIT_WORK(&othercon->swork, process_send_sockets);
802                         INIT_WORK(&othercon->rwork, process_recv_sockets);
803                         set_bit(CF_IS_OTHERCON, &othercon->flags);
804                 }
805                 if (!othercon->sock) {
806                         newcon->othercon = othercon;
807                         othercon->sock = newsock;
808                         newsock->sk->sk_user_data = othercon;
809                         add_sock(newsock, othercon);
810                         addcon = othercon;
811                 }
812                 else {
813                         printk("Extra connection from node %d attempted\n", nodeid);
814                         result = -EAGAIN;
815                         mutex_unlock(&newcon->sock_mutex);
816                         goto accept_err;
817                 }
818         }
819         else {
820                 newsock->sk->sk_user_data = newcon;
821                 newcon->rx_action = receive_from_sock;
822                 add_sock(newsock, newcon);
823                 addcon = newcon;
824         }
825 
826         mutex_unlock(&newcon->sock_mutex);
827 
828         /*
829          * Add it to the active queue in case we got data
830          * between processing the accept adding the socket
831          * to the read_sockets list
832          */
833         if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
834                 queue_work(recv_workqueue, &addcon->rwork);
835         mutex_unlock(&con->sock_mutex);
836 
837         return 0;
838 
839 accept_err:
840         mutex_unlock(&con->sock_mutex);
841         sock_release(newsock);
842 
843         if (result != -EAGAIN)
844                 log_print("error accepting connection from node: %d", result);
845         return result;
846 }
847 
848 static int sctp_accept_from_sock(struct connection *con)
849 {
850         /* Check that the new node is in the lockspace */
851         struct sctp_prim prim;
852         int nodeid;
853         int prim_len, ret;
854         int addr_len;
855         struct connection *newcon;
856         struct connection *addcon;
857         struct socket *newsock;
858 
859         mutex_lock(&connections_lock);
860         if (!dlm_allow_conn) {
861                 mutex_unlock(&connections_lock);
862                 return -1;
863         }
864         mutex_unlock(&connections_lock);
865 
866         mutex_lock_nested(&con->sock_mutex, 0);
867 
868         ret = kernel_accept(con->sock, &newsock, O_NONBLOCK);
869         if (ret < 0)
870                 goto accept_err;
871 
872         memset(&prim, 0, sizeof(struct sctp_prim));
873         prim_len = sizeof(struct sctp_prim);
874 
875         ret = kernel_getsockopt(newsock, IPPROTO_SCTP, SCTP_PRIMARY_ADDR,
876                                 (char *)&prim, &prim_len);
877         if (ret < 0) {
878                 log_print("getsockopt/sctp_primary_addr failed: %d", ret);
879                 goto accept_err;
880         }
881 
882         make_sockaddr(&prim.ssp_addr, 0, &addr_len);
883         if (addr_to_nodeid(&prim.ssp_addr, &nodeid)) {
884                 unsigned char *b = (unsigned char *)&prim.ssp_addr;
885 
886                 log_print("reject connect from unknown addr");
887                 print_hex_dump_bytes("ss: ", DUMP_PREFIX_NONE,
888                                      b, sizeof(struct sockaddr_storage));
889                 goto accept_err;
890         }
891 
892         newcon = nodeid2con(nodeid, GFP_NOFS);
893         if (!newcon) {
894                 ret = -ENOMEM;
895                 goto accept_err;
896         }
897 
898         mutex_lock_nested(&newcon->sock_mutex, 1);
899 
900         if (newcon->sock) {
901                 struct connection *othercon = newcon->othercon;
902 
903                 if (!othercon) {
904                         othercon = kmem_cache_zalloc(con_cache, GFP_NOFS);
905                         if (!othercon) {
906                                 log_print("failed to allocate incoming socket");
907                                 mutex_unlock(&newcon->sock_mutex);
908                                 ret = -ENOMEM;
909                                 goto accept_err;
910                         }
911                         othercon->nodeid = nodeid;
912                         othercon->rx_action = receive_from_sock;
913                         mutex_init(&othercon->sock_mutex);
914                         INIT_WORK(&othercon->swork, process_send_sockets);
915                         INIT_WORK(&othercon->rwork, process_recv_sockets);
916                         set_bit(CF_IS_OTHERCON, &othercon->flags);
917                 }
918                 if (!othercon->sock) {
919                         newcon->othercon = othercon;
920                         othercon->sock = newsock;
921                         newsock->sk->sk_user_data = othercon;
922                         add_sock(newsock, othercon);
923                         addcon = othercon;
924                 } else {
925                         printk("Extra connection from node %d attempted\n", nodeid);
926                         ret = -EAGAIN;
927                         mutex_unlock(&newcon->sock_mutex);
928                         goto accept_err;
929                 }
930         } else {
931                 newsock->sk->sk_user_data = newcon;
932                 newcon->rx_action = receive_from_sock;
933                 add_sock(newsock, newcon);
934                 addcon = newcon;
935         }
936 
937         log_print("connected to %d", nodeid);
938 
939         mutex_unlock(&newcon->sock_mutex);
940 
941         /*
942          * Add it to the active queue in case we got data
943          * between processing the accept adding the socket
944          * to the read_sockets list
945          */
946         if (!test_and_set_bit(CF_READ_PENDING, &addcon->flags))
947                 queue_work(recv_workqueue, &addcon->rwork);
948         mutex_unlock(&con->sock_mutex);
949 
950         return 0;
951 
952 accept_err:
953         mutex_unlock(&con->sock_mutex);
954         if (newsock)
955                 sock_release(newsock);
956         if (ret != -EAGAIN)
957                 log_print("error accepting connection from node: %d", ret);
958 
959         return ret;
960 }
961 
962 static void free_entry(struct writequeue_entry *e)
963 {
964         __free_page(e->page);
965         kfree(e);
966 }
967 
968 /*
969  * writequeue_entry_complete - try to delete and free write queue entry
970  * @e: write queue entry to try to delete
971  * @completed: bytes completed
972  *
973  * writequeue_lock must be held.
974  */
975 static void writequeue_entry_complete(struct writequeue_entry *e, int completed)
976 {
977         e->offset += completed;
978         e->len -= completed;
979 
980         if (e->len == 0 && e->users == 0) {
981                 list_del(&e->list);
982                 free_entry(e);
983         }
984 }
985 
986 /*
987  * sctp_bind_addrs - bind a SCTP socket to all our addresses
988  */
989 static int sctp_bind_addrs(struct connection *con, uint16_t port)
990 {
991         struct sockaddr_storage localaddr;
992         int i, addr_len, result = 0;
993 
994         for (i = 0; i < dlm_local_count; i++) {
995                 memcpy(&localaddr, dlm_local_addr[i], sizeof(localaddr));
996                 make_sockaddr(&localaddr, port, &addr_len);
997 
998                 if (!i)
999                         result = kernel_bind(con->sock,
1000                                              (struct sockaddr *)&localaddr,
1001                                              addr_len);
1002                 else
1003                         result = kernel_setsockopt(con->sock, SOL_SCTP,
1004                                                    SCTP_SOCKOPT_BINDX_ADD,
1005                                                    (char *)&localaddr, addr_len);
1006 
1007                 if (result < 0) {
1008                         log_print("Can't bind to %d addr number %d, %d.\n",
1009                                   port, i + 1, result);
1010                         break;
1011                 }
1012         }
1013         return result;
1014 }
1015 
1016 /* Initiate an SCTP association.
1017    This is a special case of send_to_sock() in that we don't yet have a
1018    peeled-off socket for this association, so we use the listening socket
1019    and add the primary IP address of the remote node.
1020  */
1021 static void sctp_connect_to_sock(struct connection *con)
1022 {
1023         struct sockaddr_storage daddr;
1024         int one = 1;
1025         int result;
1026         int addr_len;
1027         struct socket *sock;
1028 
1029         if (con->nodeid == 0) {
1030                 log_print("attempt to connect sock 0 foiled");
1031                 return;
1032         }
1033 
1034         mutex_lock(&con->sock_mutex);
1035 
1036         /* Some odd races can cause double-connects, ignore them */
1037         if (con->retries++ > MAX_CONNECT_RETRIES)
1038                 goto out;
1039 
1040         if (con->sock) {
1041                 log_print("node %d already connected.", con->nodeid);
1042                 goto out;
1043         }
1044 
1045         memset(&daddr, 0, sizeof(daddr));
1046         result = nodeid_to_addr(con->nodeid, &daddr, NULL, true);
1047         if (result < 0) {
1048                 log_print("no address for nodeid %d", con->nodeid);
1049                 goto out;
1050         }
1051 
1052         /* Create a socket to communicate with */
1053         result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
1054                                   SOCK_STREAM, IPPROTO_SCTP, &sock);
1055         if (result < 0)
1056                 goto socket_err;
1057 
1058         sock->sk->sk_user_data = con;
1059         con->rx_action = receive_from_sock;
1060         con->connect_action = sctp_connect_to_sock;
1061         add_sock(sock, con);
1062 
1063         /* Bind to all addresses. */
1064         if (sctp_bind_addrs(con, 0))
1065                 goto bind_err;
1066 
1067         make_sockaddr(&daddr, dlm_config.ci_tcp_port, &addr_len);
1068 
1069         log_print("connecting to %d", con->nodeid);
1070 
1071         /* Turn off Nagle's algorithm */
1072         kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
1073                           sizeof(one));
1074 
1075         result = sock->ops->connect(sock, (struct sockaddr *)&daddr, addr_len,
1076                                    O_NONBLOCK);
1077         if (result == -EINPROGRESS)
1078                 result = 0;
1079         if (result == 0)
1080                 goto out;
1081 
1082 
1083 bind_err:
1084         con->sock = NULL;
1085         sock_release(sock);
1086 
1087 socket_err:
1088         /*
1089          * Some errors are fatal and this list might need adjusting. For other
1090          * errors we try again until the max number of retries is reached.
1091          */
1092         if (result != -EHOSTUNREACH &&
1093             result != -ENETUNREACH &&
1094             result != -ENETDOWN &&
1095             result != -EINVAL &&
1096             result != -EPROTONOSUPPORT) {
1097                 log_print("connect %d try %d error %d", con->nodeid,
1098                           con->retries, result);
1099                 mutex_unlock(&con->sock_mutex);
1100                 msleep(1000);
1101                 clear_bit(CF_CONNECT_PENDING, &con->flags);
1102                 lowcomms_connect_sock(con);
1103                 return;
1104         }
1105 
1106 out:
1107         mutex_unlock(&con->sock_mutex);
1108         set_bit(CF_WRITE_PENDING, &con->flags);
1109 }
1110 
1111 /* Connect a new socket to its peer */
1112 static void tcp_connect_to_sock(struct connection *con)
1113 {
1114         struct sockaddr_storage saddr, src_addr;
1115         int addr_len;
1116         struct socket *sock = NULL;
1117         int one = 1;
1118         int result;
1119 
1120         if (con->nodeid == 0) {
1121                 log_print("attempt to connect sock 0 foiled");
1122                 return;
1123         }
1124 
1125         mutex_lock(&con->sock_mutex);
1126         if (con->retries++ > MAX_CONNECT_RETRIES)
1127                 goto out;
1128 
1129         /* Some odd races can cause double-connects, ignore them */
1130         if (con->sock)
1131                 goto out;
1132 
1133         /* Create a socket to communicate with */
1134         result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
1135                                   SOCK_STREAM, IPPROTO_TCP, &sock);
1136         if (result < 0)
1137                 goto out_err;
1138 
1139         memset(&saddr, 0, sizeof(saddr));
1140         result = nodeid_to_addr(con->nodeid, &saddr, NULL, false);
1141         if (result < 0) {
1142                 log_print("no address for nodeid %d", con->nodeid);
1143                 goto out_err;
1144         }
1145 
1146         sock->sk->sk_user_data = con;
1147         con->rx_action = receive_from_sock;
1148         con->connect_action = tcp_connect_to_sock;
1149         add_sock(sock, con);
1150 
1151         /* Bind to our cluster-known address connecting to avoid
1152            routing problems */
1153         memcpy(&src_addr, dlm_local_addr[0], sizeof(src_addr));
1154         make_sockaddr(&src_addr, 0, &addr_len);
1155         result = sock->ops->bind(sock, (struct sockaddr *) &src_addr,
1156                                  addr_len);
1157         if (result < 0) {
1158                 log_print("could not bind for connect: %d", result);
1159                 /* This *may* not indicate a critical error */
1160         }
1161 
1162         make_sockaddr(&saddr, dlm_config.ci_tcp_port, &addr_len);
1163 
1164         log_print("connecting to %d", con->nodeid);
1165 
1166         /* Turn off Nagle's algorithm */
1167         kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
1168                           sizeof(one));
1169 
1170         result = sock->ops->connect(sock, (struct sockaddr *)&saddr, addr_len,
1171                                    O_NONBLOCK);
1172         if (result == -EINPROGRESS)
1173                 result = 0;
1174         if (result == 0)
1175                 goto out;
1176 
1177 out_err:
1178         if (con->sock) {
1179                 sock_release(con->sock);
1180                 con->sock = NULL;
1181         } else if (sock) {
1182                 sock_release(sock);
1183         }
1184         /*
1185          * Some errors are fatal and this list might need adjusting. For other
1186          * errors we try again until the max number of retries is reached.
1187          */
1188         if (result != -EHOSTUNREACH &&
1189             result != -ENETUNREACH &&
1190             result != -ENETDOWN && 
1191             result != -EINVAL &&
1192             result != -EPROTONOSUPPORT) {
1193                 log_print("connect %d try %d error %d", con->nodeid,
1194                           con->retries, result);
1195                 mutex_unlock(&con->sock_mutex);
1196                 msleep(1000);
1197                 clear_bit(CF_CONNECT_PENDING, &con->flags);
1198                 lowcomms_connect_sock(con);
1199                 return;
1200         }
1201 out:
1202         mutex_unlock(&con->sock_mutex);
1203         set_bit(CF_WRITE_PENDING, &con->flags);
1204         return;
1205 }
1206 
1207 static struct socket *tcp_create_listen_sock(struct connection *con,
1208                                              struct sockaddr_storage *saddr)
1209 {
1210         struct socket *sock = NULL;
1211         int result = 0;
1212         int one = 1;
1213         int addr_len;
1214 
1215         if (dlm_local_addr[0]->ss_family == AF_INET)
1216                 addr_len = sizeof(struct sockaddr_in);
1217         else
1218                 addr_len = sizeof(struct sockaddr_in6);
1219 
1220         /* Create a socket to communicate with */
1221         result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
1222                                   SOCK_STREAM, IPPROTO_TCP, &sock);
1223         if (result < 0) {
1224                 log_print("Can't create listening comms socket");
1225                 goto create_out;
1226         }
1227 
1228         /* Turn off Nagle's algorithm */
1229         kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY, (char *)&one,
1230                           sizeof(one));
1231 
1232         result = kernel_setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
1233                                    (char *)&one, sizeof(one));
1234 
1235         if (result < 0) {
1236                 log_print("Failed to set SO_REUSEADDR on socket: %d", result);
1237         }
1238         sock->sk->sk_user_data = con;
1239 
1240         con->rx_action = tcp_accept_from_sock;
1241         con->connect_action = tcp_connect_to_sock;
1242 
1243         /* Bind to our port */
1244         make_sockaddr(saddr, dlm_config.ci_tcp_port, &addr_len);
1245         result = sock->ops->bind(sock, (struct sockaddr *) saddr, addr_len);
1246         if (result < 0) {
1247                 log_print("Can't bind to port %d", dlm_config.ci_tcp_port);
1248                 sock_release(sock);
1249                 sock = NULL;
1250                 con->sock = NULL;
1251                 goto create_out;
1252         }
1253         result = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
1254                                  (char *)&one, sizeof(one));
1255         if (result < 0) {
1256                 log_print("Set keepalive failed: %d", result);
1257         }
1258 
1259         result = sock->ops->listen(sock, 5);
1260         if (result < 0) {
1261                 log_print("Can't listen on port %d", dlm_config.ci_tcp_port);
1262                 sock_release(sock);
1263                 sock = NULL;
1264                 goto create_out;
1265         }
1266 
1267 create_out:
1268         return sock;
1269 }
1270 
1271 /* Get local addresses */
1272 static void init_local(void)
1273 {
1274         struct sockaddr_storage sas, *addr;
1275         int i;
1276 
1277         dlm_local_count = 0;
1278         for (i = 0; i < DLM_MAX_ADDR_COUNT; i++) {
1279                 if (dlm_our_addr(&sas, i))
1280                         break;
1281 
1282                 addr = kmalloc(sizeof(*addr), GFP_NOFS);
1283                 if (!addr)
1284                         break;
1285                 memcpy(addr, &sas, sizeof(*addr));
1286                 dlm_local_addr[dlm_local_count++] = addr;
1287         }
1288 }
1289 
1290 /* Initialise SCTP socket and bind to all interfaces */
1291 static int sctp_listen_for_all(void)
1292 {
1293         struct socket *sock = NULL;
1294         int result = -EINVAL;
1295         struct connection *con = nodeid2con(0, GFP_NOFS);
1296         int bufsize = NEEDED_RMEM;
1297         int one = 1;
1298 
1299         if (!con)
1300                 return -ENOMEM;
1301 
1302         log_print("Using SCTP for communications");
1303 
1304         result = sock_create_kern(&init_net, dlm_local_addr[0]->ss_family,
1305                                   SOCK_STREAM, IPPROTO_SCTP, &sock);
1306         if (result < 0) {
1307                 log_print("Can't create comms socket, check SCTP is loaded");
1308                 goto out;
1309         }
1310 
1311         result = kernel_setsockopt(sock, SOL_SOCKET, SO_RCVBUFFORCE,
1312                                  (char *)&bufsize, sizeof(bufsize));
1313         if (result)
1314                 log_print("Error increasing buffer space on socket %d", result);
1315 
1316         result = kernel_setsockopt(sock, SOL_SCTP, SCTP_NODELAY, (char *)&one,
1317                                    sizeof(one));
1318         if (result < 0)
1319                 log_print("Could not set SCTP NODELAY error %d\n", result);
1320 
1321         write_lock_bh(&sock->sk->sk_callback_lock);
1322         /* Init con struct */
1323         sock->sk->sk_user_data = con;
1324         con->sock = sock;
1325         con->sock->sk->sk_data_ready = lowcomms_data_ready;
1326         con->rx_action = sctp_accept_from_sock;
1327         con->connect_action = sctp_connect_to_sock;
1328 
1329         write_unlock_bh(&sock->sk->sk_callback_lock);
1330 
1331         /* Bind to all addresses. */
1332         if (sctp_bind_addrs(con, dlm_config.ci_tcp_port))
1333                 goto create_delsock;
1334 
1335         result = sock->ops->listen(sock, 5);
1336         if (result < 0) {
1337                 log_print("Can't set socket listening");
1338                 goto create_delsock;
1339         }
1340 
1341         return 0;
1342 
1343 create_delsock:
1344         sock_release(sock);
1345         con->sock = NULL;
1346 out:
1347         return result;
1348 }
1349 
1350 static int tcp_listen_for_all(void)
1351 {
1352         struct socket *sock = NULL;
1353         struct connection *con = nodeid2con(0, GFP_NOFS);
1354         int result = -EINVAL;
1355 
1356         if (!con)
1357                 return -ENOMEM;
1358 
1359         /* We don't support multi-homed hosts */
1360         if (dlm_local_addr[1] != NULL) {
1361                 log_print("TCP protocol can't handle multi-homed hosts, "
1362                           "try SCTP");
1363                 return -EINVAL;
1364         }
1365 
1366         log_print("Using TCP for communications");
1367 
1368         sock = tcp_create_listen_sock(con, dlm_local_addr[0]);
1369         if (sock) {
1370                 add_sock(sock, con);
1371                 result = 0;
1372         }
1373         else {
1374                 result = -EADDRINUSE;
1375         }
1376 
1377         return result;
1378 }
1379 
1380 
1381 
1382 static struct writequeue_entry *new_writequeue_entry(struct connection *con,
1383                                                      gfp_t allocation)
1384 {
1385         struct writequeue_entry *entry;
1386 
1387         entry = kmalloc(sizeof(struct writequeue_entry), allocation);
1388         if (!entry)
1389                 return NULL;
1390 
1391         entry->page = alloc_page(allocation);
1392         if (!entry->page) {
1393                 kfree(entry);
1394                 return NULL;
1395         }
1396 
1397         entry->offset = 0;
1398         entry->len = 0;
1399         entry->end = 0;
1400         entry->users = 0;
1401         entry->con = con;
1402 
1403         return entry;
1404 }
1405 
1406 void *dlm_lowcomms_get_buffer(int nodeid, int len, gfp_t allocation, char **ppc)
1407 {
1408         struct connection *con;
1409         struct writequeue_entry *e;
1410         int offset = 0;
1411 
1412         con = nodeid2con(nodeid, allocation);
1413         if (!con)
1414                 return NULL;
1415 
1416         spin_lock(&con->writequeue_lock);
1417         e = list_entry(con->writequeue.prev, struct writequeue_entry, list);
1418         if ((&e->list == &con->writequeue) ||
1419             (PAGE_SIZE - e->end < len)) {
1420                 e = NULL;
1421         } else {
1422                 offset = e->end;
1423                 e->end += len;
1424                 e->users++;
1425         }
1426         spin_unlock(&con->writequeue_lock);
1427 
1428         if (e) {
1429         got_one:
1430                 *ppc = page_address(e->page) + offset;
1431                 return e;
1432         }
1433 
1434         e = new_writequeue_entry(con, allocation);
1435         if (e) {
1436                 spin_lock(&con->writequeue_lock);
1437                 offset = e->end;
1438                 e->end += len;
1439                 e->users++;
1440                 list_add_tail(&e->list, &con->writequeue);
1441                 spin_unlock(&con->writequeue_lock);
1442                 goto got_one;
1443         }
1444         return NULL;
1445 }
1446 
1447 void dlm_lowcomms_commit_buffer(void *mh)
1448 {
1449         struct writequeue_entry *e = (struct writequeue_entry *)mh;
1450         struct connection *con = e->con;
1451         int users;
1452 
1453         spin_lock(&con->writequeue_lock);
1454         users = --e->users;
1455         if (users)
1456                 goto out;
1457         e->len = e->end - e->offset;
1458         spin_unlock(&con->writequeue_lock);
1459 
1460         if (!test_and_set_bit(CF_WRITE_PENDING, &con->flags)) {
1461                 queue_work(send_workqueue, &con->swork);
1462         }
1463         return;
1464 
1465 out:
1466         spin_unlock(&con->writequeue_lock);
1467         return;
1468 }
1469 
1470 /* Send a message */
1471 static void send_to_sock(struct connection *con)
1472 {
1473         int ret = 0;
1474         const int msg_flags = MSG_DONTWAIT | MSG_NOSIGNAL;
1475         struct writequeue_entry *e;
1476         int len, offset;
1477         int count = 0;
1478 
1479         mutex_lock(&con->sock_mutex);
1480         if (con->sock == NULL)
1481                 goto out_connect;
1482 
1483         spin_lock(&con->writequeue_lock);
1484         for (;;) {
1485                 e = list_entry(con->writequeue.next, struct writequeue_entry,
1486                                list);
1487                 if ((struct list_head *) e == &con->writequeue)
1488                         break;
1489 
1490                 len = e->len;
1491                 offset = e->offset;
1492                 BUG_ON(len == 0 && e->users == 0);
1493                 spin_unlock(&con->writequeue_lock);
1494 
1495                 ret = 0;
1496                 if (len) {
1497                         ret = kernel_sendpage(con->sock, e->page, offset, len,
1498                                               msg_flags);
1499                         if (ret == -EAGAIN || ret == 0) {
1500                                 if (ret == -EAGAIN &&
1501                                     test_bit(SOCKWQ_ASYNC_NOSPACE, &con->sock->flags) &&
1502                                     !test_and_set_bit(CF_APP_LIMITED, &con->flags)) {
1503                                         /* Notify TCP that we're limited by the
1504                                          * application window size.
1505                                          */
1506                                         set_bit(SOCK_NOSPACE, &con->sock->flags);
1507                                         con->sock->sk->sk_write_pending++;
1508                                 }
1509                                 cond_resched();
1510                                 goto out;
1511                         } else if (ret < 0)
1512                                 goto send_error;
1513                 }
1514 
1515                 /* Don't starve people filling buffers */
1516                 if (++count >= MAX_SEND_MSG_COUNT) {
1517                         cond_resched();
1518                         count = 0;
1519                 }
1520 
1521                 spin_lock(&con->writequeue_lock);
1522                 writequeue_entry_complete(e, ret);
1523         }
1524         spin_unlock(&con->writequeue_lock);
1525 out:
1526         mutex_unlock(&con->sock_mutex);
1527         return;
1528 
1529 send_error:
1530         mutex_unlock(&con->sock_mutex);
1531         close_connection(con, false, false, true);
1532         lowcomms_connect_sock(con);
1533         return;
1534 
1535 out_connect:
1536         mutex_unlock(&con->sock_mutex);
1537         lowcomms_connect_sock(con);
1538 }
1539 
1540 static void clean_one_writequeue(struct connection *con)
1541 {
1542         struct writequeue_entry *e, *safe;
1543 
1544         spin_lock(&con->writequeue_lock);
1545         list_for_each_entry_safe(e, safe, &con->writequeue, list) {
1546                 list_del(&e->list);
1547                 free_entry(e);
1548         }
1549         spin_unlock(&con->writequeue_lock);
1550 }
1551 
1552 /* Called from recovery when it knows that a node has
1553    left the cluster */
1554 int dlm_lowcomms_close(int nodeid)
1555 {
1556         struct connection *con;
1557         struct dlm_node_addr *na;
1558 
1559         log_print("closing connection to node %d", nodeid);
1560         con = nodeid2con(nodeid, 0);
1561         if (con) {
1562                 set_bit(CF_CLOSE, &con->flags);
1563                 close_connection(con, true, true, true);
1564                 clean_one_writequeue(con);
1565         }
1566 
1567         spin_lock(&dlm_node_addrs_spin);
1568         na = find_node_addr(nodeid);
1569         if (na) {
1570                 list_del(&na->list);
1571                 while (na->addr_count--)
1572                         kfree(na->addr[na->addr_count]);
1573                 kfree(na);
1574         }
1575         spin_unlock(&dlm_node_addrs_spin);
1576 
1577         return 0;
1578 }
1579 
1580 /* Receive workqueue function */
1581 static void process_recv_sockets(struct work_struct *work)
1582 {
1583         struct connection *con = container_of(work, struct connection, rwork);
1584         int err;
1585 
1586         clear_bit(CF_READ_PENDING, &con->flags);
1587         do {
1588                 err = con->rx_action(con);
1589         } while (!err);
1590 }
1591 
1592 /* Send workqueue function */
1593 static void process_send_sockets(struct work_struct *work)
1594 {
1595         struct connection *con = container_of(work, struct connection, swork);
1596 
1597         if (test_and_clear_bit(CF_CONNECT_PENDING, &con->flags))
1598                 con->connect_action(con);
1599         if (test_and_clear_bit(CF_WRITE_PENDING, &con->flags))
1600                 send_to_sock(con);
1601 }
1602 
1603 
1604 /* Discard all entries on the write queues */
1605 static void clean_writequeues(void)
1606 {
1607         foreach_conn(clean_one_writequeue);
1608 }
1609 
1610 static void work_stop(void)
1611 {
1612         destroy_workqueue(recv_workqueue);
1613         destroy_workqueue(send_workqueue);
1614 }
1615 
1616 static int work_start(void)
1617 {
1618         recv_workqueue = alloc_workqueue("dlm_recv",
1619                                          WQ_UNBOUND | WQ_MEM_RECLAIM, 1);
1620         if (!recv_workqueue) {
1621                 log_print("can't start dlm_recv");
1622                 return -ENOMEM;
1623         }
1624 
1625         send_workqueue = alloc_workqueue("dlm_send",
1626                                          WQ_UNBOUND | WQ_MEM_RECLAIM, 1);
1627         if (!send_workqueue) {
1628                 log_print("can't start dlm_send");
1629                 destroy_workqueue(recv_workqueue);
1630                 return -ENOMEM;
1631         }
1632 
1633         return 0;
1634 }
1635 
1636 static void stop_conn(struct connection *con)
1637 {
1638         con->flags |= 0x0F;
1639         if (con->sock && con->sock->sk)
1640                 con->sock->sk->sk_user_data = NULL;
1641 }
1642 
1643 static void free_conn(struct connection *con)
1644 {
1645         close_connection(con, true, true, true);
1646         if (con->othercon)
1647                 kmem_cache_free(con_cache, con->othercon);
1648         hlist_del(&con->list);
1649         kmem_cache_free(con_cache, con);
1650 }
1651 
1652 void dlm_lowcomms_stop(void)
1653 {
1654         /* Set all the flags to prevent any
1655            socket activity.
1656         */
1657         mutex_lock(&connections_lock);
1658         dlm_allow_conn = 0;
1659         foreach_conn(stop_conn);
1660         mutex_unlock(&connections_lock);
1661 
1662         work_stop();
1663 
1664         mutex_lock(&connections_lock);
1665         clean_writequeues();
1666 
1667         foreach_conn(free_conn);
1668 
1669         mutex_unlock(&connections_lock);
1670         kmem_cache_destroy(con_cache);
1671 }
1672 
1673 int dlm_lowcomms_start(void)
1674 {
1675         int error = -EINVAL;
1676         struct connection *con;
1677         int i;
1678 
1679         for (i = 0; i < CONN_HASH_SIZE; i++)
1680                 INIT_HLIST_HEAD(&connection_hash[i]);
1681 
1682         init_local();
1683         if (!dlm_local_count) {
1684                 error = -ENOTCONN;
1685                 log_print("no local IP address has been set");
1686                 goto fail;
1687         }
1688 
1689         error = -ENOMEM;
1690         con_cache = kmem_cache_create("dlm_conn", sizeof(struct connection),
1691                                       __alignof__(struct connection), 0,
1692                                       NULL);
1693         if (!con_cache)
1694                 goto fail;
1695 
1696         error = work_start();
1697         if (error)
1698                 goto fail_destroy;
1699 
1700         dlm_allow_conn = 1;
1701 
1702         /* Start listening */
1703         if (dlm_config.ci_protocol == 0)
1704                 error = tcp_listen_for_all();
1705         else
1706                 error = sctp_listen_for_all();
1707         if (error)
1708                 goto fail_unlisten;
1709 
1710         return 0;
1711 
1712 fail_unlisten:
1713         dlm_allow_conn = 0;
1714         con = nodeid2con(0,0);
1715         if (con) {
1716                 close_connection(con, false, true, true);
1717                 kmem_cache_free(con_cache, con);
1718         }
1719 fail_destroy:
1720         kmem_cache_destroy(con_cache);
1721 fail:
1722         return error;
1723 }
1724 
1725 void dlm_lowcomms_exit(void)
1726 {
1727         struct dlm_node_addr *na, *safe;
1728 
1729         spin_lock(&dlm_node_addrs_spin);
1730         list_for_each_entry_safe(na, safe, &dlm_node_addrs, list) {
1731                 list_del(&na->list);
1732                 while (na->addr_count--)
1733                         kfree(na->addr[na->addr_count]);
1734                 kfree(na);
1735         }
1736         spin_unlock(&dlm_node_addrs_spin);
1737 }
1738 

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