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
18 #define NLMDBG_FACILITY NLMDBG_CLIENT
19
20 /*
21 * Local function prototypes
22 */
23 static int reclaimer(void *ptr);
24
25 /*
26 * The following functions handle blocking and granting from the
27 * client perspective.
28 */
29
30 /*
31 * This is the representation of a blocked client lock.
32 */
33 struct nlm_wait {
34 struct list_head b_list; /* linked list */
35 wait_queue_head_t b_wait; /* where to wait on */
36 struct nlm_host * b_host;
37 struct file_lock * b_lock; /* local file lock */
38 unsigned short b_reclaim; /* got to reclaim lock */
39 __be32 b_status; /* grant callback status */
40 };
41
42 static LIST_HEAD(nlm_blocked);
43
44 /**
45 * nlmclnt_init - Set up per-NFS mount point lockd data structures
46 * @nlm_init: pointer to arguments structure
47 *
48 * Returns pointer to an appropriate nlm_host struct,
49 * or an ERR_PTR value.
50 */
51 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
52 {
53 struct nlm_host *host;
54 u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
55 int status;
56
57 status = lockd_up(nlm_init->protocol);
58 if (status < 0)
59 return ERR_PTR(status);
60
61 host = nlmclnt_lookup_host((struct sockaddr_in *)nlm_init->address,
62 nlm_init->protocol, nlm_version,
63 nlm_init->hostname,
64 strlen(nlm_init->hostname));
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 */
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 */
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
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 */
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 /*
143 * The server lockd has called us back to tell us the lock was granted
144 */
145 __be32 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock)
146 {
147 const struct file_lock *fl = &lock->fl;
148 const struct nfs_fh *fh = &lock->fh;
149 struct nlm_wait *block;
150 __be32 res = nlm_lck_denied;
151
152 /*
153 * Look up blocked request based on arguments.
154 * Warning: must not use cookie to match it!
155 */
156 list_for_each_entry(block, &nlm_blocked, b_list) {
157 struct file_lock *fl_blocked = block->b_lock;
158
159 if (fl_blocked->fl_start != fl->fl_start)
160 continue;
161 if (fl_blocked->fl_end != fl->fl_end)
162 continue;
163 /*
164 * Careful! The NLM server will return the 32-bit "pid" that
165 * we put on the wire: in this case the lockowner "pid".
166 */
167 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
168 continue;
169 if (!nlm_cmp_addr(&block->b_host->h_addr, addr))
170 continue;
171 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
172 continue;
173 /* Alright, we found a lock. Set the return status
174 * and wake up the caller
175 */
176 block->b_status = nlm_granted;
177 wake_up(&block->b_wait);
178 res = nlm_granted;
179 }
180 return res;
181 }
182
183 /*
184 * The following procedures deal with the recovery of locks after a
185 * server crash.
186 */
187
188 /*
189 * Reclaim all locks on server host. We do this by spawning a separate
190 * reclaimer thread.
191 */
192 void
193 nlmclnt_recovery(struct nlm_host *host)
194 {
195 if (!host->h_reclaiming++) {
196 nlm_get_host(host);
197 __module_get(THIS_MODULE);
198 if (kernel_thread(reclaimer, host, CLONE_FS | CLONE_FILES) < 0)
199 module_put(THIS_MODULE);
200 }
201 }
202
203 static int
204 reclaimer(void *ptr)
205 {
206 struct nlm_host *host = (struct nlm_host *) ptr;
207 struct nlm_wait *block;
208 struct file_lock *fl, *next;
209 u32 nsmstate;
210
211 daemonize("%s-reclaim", host->h_name);
212 allow_signal(SIGKILL);
213
214 down_write(&host->h_rwsem);
215
216 /* This one ensures that our parent doesn't terminate while the
217 * reclaim is in progress */
218 lock_kernel();
219 lockd_up(0); /* note: this cannot fail as lockd is already running */
220
221 dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
222
223 restart:
224 nsmstate = host->h_nsmstate;
225
226 /* Force a portmap getport - the peer's lockd will
227 * most likely end up on a different port.
228 */
229 host->h_nextrebind = jiffies;
230 nlm_rebind_host(host);
231
232 /* First, reclaim all locks that have been granted. */
233 list_splice_init(&host->h_granted, &host->h_reclaim);
234 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
235 list_del_init(&fl->fl_u.nfs_fl.list);
236
237 /* Why are we leaking memory here? --okir */
238 if (signalled())
239 continue;
240 if (nlmclnt_reclaim(host, fl) != 0)
241 continue;
242 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
243 if (host->h_nsmstate != nsmstate) {
244 /* Argh! The server rebooted again! */
245 goto restart;
246 }
247 }
248
249 host->h_reclaiming = 0;
250 up_write(&host->h_rwsem);
251 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
252
253 /* Now, wake up all processes that sleep on a blocked lock */
254 list_for_each_entry(block, &nlm_blocked, b_list) {
255 if (block->b_host == host) {
256 block->b_status = nlm_lck_denied_grace_period;
257 wake_up(&block->b_wait);
258 }
259 }
260
261 /* Release host handle after use */
262 nlm_release_host(host);
263 lockd_down();
264 unlock_kernel();
265 module_put_and_exit(0);
266 }
267
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