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/slab.h>
12 #include <linux/time.h>
13 #include <linux/nfs_fs.h>
14 #include <linux/sunrpc/clnt.h>
15 #include <linux/sunrpc/svc.h>
16 #include <linux/lockd/lockd.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 static DEFINE_SPINLOCK(nlm_blocked_lock);
45
46 /**
47 * nlmclnt_init - Set up per-NFS mount point lockd data structures
48 * @nlm_init: pointer to arguments structure
49 *
50 * Returns pointer to an appropriate nlm_host struct,
51 * or an ERR_PTR value.
52 */
nlmclnt_init(const struct nlmclnt_initdata * nlm_init)53 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
54 {
55 struct nlm_host *host;
56 u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
57 int status;
58
59 status = lockd_up(nlm_init->net);
60 if (status < 0)
61 return ERR_PTR(status);
62
63 host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen,
64 nlm_init->protocol, nlm_version,
65 nlm_init->hostname, nlm_init->noresvport,
66 nlm_init->net);
67 if (host == NULL) {
68 lockd_down(nlm_init->net);
69 return ERR_PTR(-ENOLCK);
70 }
71
72 return host;
73 }
74 EXPORT_SYMBOL_GPL(nlmclnt_init);
75
76 /**
77 * nlmclnt_done - Release resources allocated by nlmclnt_init()
78 * @host: nlm_host structure reserved by nlmclnt_init()
79 *
80 */
nlmclnt_done(struct nlm_host * host)81 void nlmclnt_done(struct nlm_host *host)
82 {
83 struct net *net = host->net;
84
85 nlmclnt_release_host(host);
86 lockd_down(net);
87 }
88 EXPORT_SYMBOL_GPL(nlmclnt_done);
89
90 /*
91 * Queue up a lock for blocking so that the GRANTED request can see it
92 */
nlmclnt_prepare_block(struct nlm_host * host,struct file_lock * fl)93 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
94 {
95 struct nlm_wait *block;
96
97 block = kmalloc(sizeof(*block), GFP_KERNEL);
98 if (block != NULL) {
99 block->b_host = host;
100 block->b_lock = fl;
101 init_waitqueue_head(&block->b_wait);
102 block->b_status = nlm_lck_blocked;
103
104 spin_lock(&nlm_blocked_lock);
105 list_add(&block->b_list, &nlm_blocked);
106 spin_unlock(&nlm_blocked_lock);
107 }
108 return block;
109 }
110
nlmclnt_finish_block(struct nlm_wait * block)111 void nlmclnt_finish_block(struct nlm_wait *block)
112 {
113 if (block == NULL)
114 return;
115 spin_lock(&nlm_blocked_lock);
116 list_del(&block->b_list);
117 spin_unlock(&nlm_blocked_lock);
118 kfree(block);
119 }
120
121 /*
122 * Block on a lock
123 */
nlmclnt_block(struct nlm_wait * block,struct nlm_rqst * req,long timeout)124 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
125 {
126 long ret;
127
128 /* A borken server might ask us to block even if we didn't
129 * request it. Just say no!
130 */
131 if (block == NULL)
132 return -EAGAIN;
133
134 /* Go to sleep waiting for GRANT callback. Some servers seem
135 * to lose callbacks, however, so we're going to poll from
136 * time to time just to make sure.
137 *
138 * For now, the retry frequency is pretty high; normally
139 * a 1 minute timeout would do. See the comment before
140 * nlmclnt_lock for an explanation.
141 */
142 ret = wait_event_interruptible_timeout(block->b_wait,
143 block->b_status != nlm_lck_blocked,
144 timeout);
145 if (ret < 0)
146 return -ERESTARTSYS;
147 /* Reset the lock status after a server reboot so we resend */
148 if (block->b_status == nlm_lck_denied_grace_period)
149 block->b_status = nlm_lck_blocked;
150 req->a_res.status = block->b_status;
151 return 0;
152 }
153
154 /*
155 * The server lockd has called us back to tell us the lock was granted
156 */
nlmclnt_grant(const struct sockaddr * addr,const struct nlm_lock * lock)157 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
158 {
159 const struct file_lock *fl = &lock->fl;
160 const struct nfs_fh *fh = &lock->fh;
161 struct nlm_wait *block;
162 __be32 res = nlm_lck_denied;
163
164 /*
165 * Look up blocked request based on arguments.
166 * Warning: must not use cookie to match it!
167 */
168 spin_lock(&nlm_blocked_lock);
169 list_for_each_entry(block, &nlm_blocked, b_list) {
170 struct file_lock *fl_blocked = block->b_lock;
171
172 if (fl_blocked->fl_start != fl->fl_start)
173 continue;
174 if (fl_blocked->fl_end != fl->fl_end)
175 continue;
176 /*
177 * Careful! The NLM server will return the 32-bit "pid" that
178 * we put on the wire: in this case the lockowner "pid".
179 */
180 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
181 continue;
182 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
183 continue;
184 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
185 continue;
186 /* Alright, we found a lock. Set the return status
187 * and wake up the caller
188 */
189 block->b_status = nlm_granted;
190 wake_up(&block->b_wait);
191 res = nlm_granted;
192 }
193 spin_unlock(&nlm_blocked_lock);
194 return res;
195 }
196
197 /*
198 * The following procedures deal with the recovery of locks after a
199 * server crash.
200 */
201
202 /*
203 * Reclaim all locks on server host. We do this by spawning a separate
204 * reclaimer thread.
205 */
206 void
nlmclnt_recovery(struct nlm_host * host)207 nlmclnt_recovery(struct nlm_host *host)
208 {
209 struct task_struct *task;
210
211 if (!host->h_reclaiming++) {
212 nlm_get_host(host);
213 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
214 if (IS_ERR(task))
215 printk(KERN_ERR "lockd: unable to spawn reclaimer "
216 "thread. Locks for %s won't be reclaimed! "
217 "(%ld)\n", host->h_name, PTR_ERR(task));
218 }
219 }
220
221 static int
reclaimer(void * ptr)222 reclaimer(void *ptr)
223 {
224 struct nlm_host *host = (struct nlm_host *) ptr;
225 struct nlm_wait *block;
226 struct file_lock *fl, *next;
227 u32 nsmstate;
228 struct net *net = host->net;
229
230 allow_signal(SIGKILL);
231
232 down_write(&host->h_rwsem);
233 lockd_up(net); /* note: this cannot fail as lockd is already running */
234
235 dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
236
237 restart:
238 nsmstate = host->h_nsmstate;
239
240 /* Force a portmap getport - the peer's lockd will
241 * most likely end up on a different port.
242 */
243 host->h_nextrebind = jiffies;
244 nlm_rebind_host(host);
245
246 /* First, reclaim all locks that have been granted. */
247 list_splice_init(&host->h_granted, &host->h_reclaim);
248 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
249 list_del_init(&fl->fl_u.nfs_fl.list);
250
251 /*
252 * sending this thread a SIGKILL will result in any unreclaimed
253 * locks being removed from the h_granted list. This means that
254 * the kernel will not attempt to reclaim them again if a new
255 * reclaimer thread is spawned for this host.
256 */
257 if (signalled())
258 continue;
259 if (nlmclnt_reclaim(host, fl) != 0)
260 continue;
261 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
262 if (host->h_nsmstate != nsmstate) {
263 /* Argh! The server rebooted again! */
264 goto restart;
265 }
266 }
267
268 host->h_reclaiming = 0;
269 up_write(&host->h_rwsem);
270 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
271
272 /* Now, wake up all processes that sleep on a blocked lock */
273 spin_lock(&nlm_blocked_lock);
274 list_for_each_entry(block, &nlm_blocked, b_list) {
275 if (block->b_host == host) {
276 block->b_status = nlm_lck_denied_grace_period;
277 wake_up(&block->b_wait);
278 }
279 }
280 spin_unlock(&nlm_blocked_lock);
281
282 /* Release host handle after use */
283 nlmclnt_release_host(host);
284 lockd_down(net);
285 return 0;
286 }
287