1 /*
2 * linux/fs/lockd/clntlock.c
3 *
4 * Lock handling for the client side NLM implementation
5 *
6 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
7 */
8
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/time.h>
12 #include <linux/nfs_fs.h>
13 #include <linux/sunrpc/clnt.h>
14 #include <linux/sunrpc/svc.h>
15 #include <linux/lockd/lockd.h>
16 #include <linux/smp_lock.h>
17 #include <linux/kthread.h>
18
19 #define NLMDBG_FACILITY NLMDBG_CLIENT
20
21 /*
22 * Local function prototypes
23 */
24 static int reclaimer(void *ptr);
25
26 /*
27 * The following functions handle blocking and granting from the
28 * client perspective.
29 */
30
31 /*
32 * This is the representation of a blocked client lock.
33 */
34 struct nlm_wait {
35 struct list_head b_list; /* linked list */
36 wait_queue_head_t b_wait; /* where to wait on */
37 struct nlm_host * b_host;
38 struct file_lock * b_lock; /* local file lock */
39 unsigned short b_reclaim; /* got to reclaim lock */
40 __be32 b_status; /* grant callback status */
41 };
42
43 static LIST_HEAD(nlm_blocked);
44
45 /**
46 * nlmclnt_init - Set up per-NFS mount point lockd data structures
47 * @nlm_init: pointer to arguments structure
48 *
49 * Returns pointer to an appropriate nlm_host struct,
50 * or an ERR_PTR value.
51 */
nlmclnt_init(const struct nlmclnt_initdata * nlm_init)52 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
53 {
54 struct nlm_host *host;
55 u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
56 int status;
57
58 status = lockd_up();
59 if (status < 0)
60 return ERR_PTR(status);
61
62 host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen,
63 nlm_init->protocol, nlm_version,
64 nlm_init->hostname, nlm_init->noresvport);
65 if (host == NULL) {
66 lockd_down();
67 return ERR_PTR(-ENOLCK);
68 }
69
70 return host;
71 }
72 EXPORT_SYMBOL_GPL(nlmclnt_init);
73
74 /**
75 * nlmclnt_done - Release resources allocated by nlmclnt_init()
76 * @host: nlm_host structure reserved by nlmclnt_init()
77 *
78 */
nlmclnt_done(struct nlm_host * host)79 void nlmclnt_done(struct nlm_host *host)
80 {
81 nlm_release_host(host);
82 lockd_down();
83 }
84 EXPORT_SYMBOL_GPL(nlmclnt_done);
85
86 /*
87 * Queue up a lock for blocking so that the GRANTED request can see it
88 */
nlmclnt_prepare_block(struct nlm_host * host,struct file_lock * fl)89 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
90 {
91 struct nlm_wait *block;
92
93 block = kmalloc(sizeof(*block), GFP_KERNEL);
94 if (block != NULL) {
95 block->b_host = host;
96 block->b_lock = fl;
97 init_waitqueue_head(&block->b_wait);
98 block->b_status = nlm_lck_blocked;
99 list_add(&block->b_list, &nlm_blocked);
100 }
101 return block;
102 }
103
nlmclnt_finish_block(struct nlm_wait * block)104 void nlmclnt_finish_block(struct nlm_wait *block)
105 {
106 if (block == NULL)
107 return;
108 list_del(&block->b_list);
109 kfree(block);
110 }
111
112 /*
113 * Block on a lock
114 */
nlmclnt_block(struct nlm_wait * block,struct nlm_rqst * req,long timeout)115 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
116 {
117 long ret;
118
119 /* A borken server might ask us to block even if we didn't
120 * request it. Just say no!
121 */
122 if (block == NULL)
123 return -EAGAIN;
124
125 /* Go to sleep waiting for GRANT callback. Some servers seem
126 * to lose callbacks, however, so we're going to poll from
127 * time to time just to make sure.
128 *
129 * For now, the retry frequency is pretty high; normally
130 * a 1 minute timeout would do. See the comment before
131 * nlmclnt_lock for an explanation.
132 */
133 ret = wait_event_interruptible_timeout(block->b_wait,
134 block->b_status != nlm_lck_blocked,
135 timeout);
136 if (ret < 0)
137 return -ERESTARTSYS;
138 req->a_res.status = block->b_status;
139 return 0;
140 }
141
142 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
nlmclnt_map_v4addr(const struct sockaddr * sap,struct in6_addr * addr_mapped)143 static const struct in6_addr *nlmclnt_map_v4addr(const struct sockaddr *sap,
144 struct in6_addr *addr_mapped)
145 {
146 const struct sockaddr_in *sin = (const struct sockaddr_in *)sap;
147
148 switch (sap->sa_family) {
149 case AF_INET6:
150 return &((const struct sockaddr_in6 *)sap)->sin6_addr;
151 case AF_INET:
152 ipv6_addr_set_v4mapped(sin->sin_addr.s_addr, addr_mapped);
153 return addr_mapped;
154 }
155
156 return NULL;
157 }
158
159 /*
160 * If lockd is using a PF_INET6 listener, all incoming requests appear
161 * to come from AF_INET6 remotes. The address of AF_INET remotes are
162 * mapped to AF_INET6 automatically by the network layer. In case the
163 * user passed an AF_INET server address at mount time, ensure both
164 * addresses are AF_INET6 before comparing them.
165 */
nlmclnt_cmp_addr(const struct nlm_host * host,const struct sockaddr * sap)166 static int nlmclnt_cmp_addr(const struct nlm_host *host,
167 const struct sockaddr *sap)
168 {
169 const struct in6_addr *addr1;
170 const struct in6_addr *addr2;
171 struct in6_addr addr1_mapped;
172 struct in6_addr addr2_mapped;
173
174 addr1 = nlmclnt_map_v4addr(nlm_addr(host), &addr1_mapped);
175 if (likely(addr1 != NULL)) {
176 addr2 = nlmclnt_map_v4addr(sap, &addr2_mapped);
177 if (likely(addr2 != NULL))
178 return ipv6_addr_equal(addr1, addr2);
179 }
180
181 return 0;
182 }
183 #else /* !(CONFIG_IPV6 || CONFIG_IPV6_MODULE) */
nlmclnt_cmp_addr(const struct nlm_host * host,const struct sockaddr * sap)184 static int nlmclnt_cmp_addr(const struct nlm_host *host,
185 const struct sockaddr *sap)
186 {
187 return nlm_cmp_addr(nlm_addr(host), sap);
188 }
189 #endif /* !(CONFIG_IPV6 || CONFIG_IPV6_MODULE) */
190
191 /*
192 * The server lockd has called us back to tell us the lock was granted
193 */
nlmclnt_grant(const struct sockaddr * addr,const struct nlm_lock * lock)194 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
195 {
196 const struct file_lock *fl = &lock->fl;
197 const struct nfs_fh *fh = &lock->fh;
198 struct nlm_wait *block;
199 __be32 res = nlm_lck_denied;
200
201 /*
202 * Look up blocked request based on arguments.
203 * Warning: must not use cookie to match it!
204 */
205 list_for_each_entry(block, &nlm_blocked, b_list) {
206 struct file_lock *fl_blocked = block->b_lock;
207
208 if (fl_blocked->fl_start != fl->fl_start)
209 continue;
210 if (fl_blocked->fl_end != fl->fl_end)
211 continue;
212 /*
213 * Careful! The NLM server will return the 32-bit "pid" that
214 * we put on the wire: in this case the lockowner "pid".
215 */
216 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
217 continue;
218 if (!nlmclnt_cmp_addr(block->b_host, addr))
219 continue;
220 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
221 continue;
222 /* Alright, we found a lock. Set the return status
223 * and wake up the caller
224 */
225 block->b_status = nlm_granted;
226 wake_up(&block->b_wait);
227 res = nlm_granted;
228 }
229 return res;
230 }
231
232 /*
233 * The following procedures deal with the recovery of locks after a
234 * server crash.
235 */
236
237 /*
238 * Reclaim all locks on server host. We do this by spawning a separate
239 * reclaimer thread.
240 */
241 void
nlmclnt_recovery(struct nlm_host * host)242 nlmclnt_recovery(struct nlm_host *host)
243 {
244 struct task_struct *task;
245
246 if (!host->h_reclaiming++) {
247 nlm_get_host(host);
248 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
249 if (IS_ERR(task))
250 printk(KERN_ERR "lockd: unable to spawn reclaimer "
251 "thread. Locks for %s won't be reclaimed! "
252 "(%ld)\n", host->h_name, PTR_ERR(task));
253 }
254 }
255
256 static int
reclaimer(void * ptr)257 reclaimer(void *ptr)
258 {
259 struct nlm_host *host = (struct nlm_host *) ptr;
260 struct nlm_wait *block;
261 struct file_lock *fl, *next;
262 u32 nsmstate;
263
264 allow_signal(SIGKILL);
265
266 down_write(&host->h_rwsem);
267
268 /* This one ensures that our parent doesn't terminate while the
269 * reclaim is in progress */
270 lock_kernel();
271 lockd_up(); /* note: this cannot fail as lockd is already running */
272
273 dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
274
275 restart:
276 nsmstate = host->h_nsmstate;
277
278 /* Force a portmap getport - the peer's lockd will
279 * most likely end up on a different port.
280 */
281 host->h_nextrebind = jiffies;
282 nlm_rebind_host(host);
283
284 /* First, reclaim all locks that have been granted. */
285 list_splice_init(&host->h_granted, &host->h_reclaim);
286 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
287 list_del_init(&fl->fl_u.nfs_fl.list);
288
289 /*
290 * sending this thread a SIGKILL will result in any unreclaimed
291 * locks being removed from the h_granted list. This means that
292 * the kernel will not attempt to reclaim them again if a new
293 * reclaimer thread is spawned for this host.
294 */
295 if (signalled())
296 continue;
297 if (nlmclnt_reclaim(host, fl) != 0)
298 continue;
299 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
300 if (host->h_nsmstate != nsmstate) {
301 /* Argh! The server rebooted again! */
302 goto restart;
303 }
304 }
305
306 host->h_reclaiming = 0;
307 up_write(&host->h_rwsem);
308 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
309
310 /* Now, wake up all processes that sleep on a blocked lock */
311 list_for_each_entry(block, &nlm_blocked, b_list) {
312 if (block->b_host == host) {
313 block->b_status = nlm_lck_denied_grace_period;
314 wake_up(&block->b_wait);
315 }
316 }
317
318 /* Release host handle after use */
319 nlm_release_host(host);
320 lockd_down();
321 unlock_kernel();
322 return 0;
323 }
324