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 nlm_wait * b_next; /* 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 u32 b_status; /* grant callback status */
40 };
41
42 static struct nlm_wait * nlm_blocked;
43
44 /*
45 * Block on a lock
46 */
47 int
48 nlmclnt_block(struct nlm_host *host, struct file_lock *fl, u32 *statp)
49 {
50 struct nlm_wait block, **head;
51 int err;
52 u32 pstate;
53
54 block.b_host = host;
55 block.b_lock = fl;
56 init_waitqueue_head(&block.b_wait);
57 block.b_status = NLM_LCK_BLOCKED;
58 block.b_next = nlm_blocked;
59 nlm_blocked = █
60
61 /* Remember pseudo nsm state */
62 pstate = host->h_state;
63
64 /* Go to sleep waiting for GRANT callback. Some servers seem
65 * to lose callbacks, however, so we're going to poll from
66 * time to time just to make sure.
67 *
68 * For now, the retry frequency is pretty high; normally
69 * a 1 minute timeout would do. See the comment before
70 * nlmclnt_lock for an explanation.
71 */
72 sleep_on_timeout(&block.b_wait, 30*HZ);
73
74 for (head = &nlm_blocked; *head; head = &(*head)->b_next) {
75 if (*head == &block) {
76 *head = block.b_next;
77 break;
78 }
79 }
80
81 if (!signalled()) {
82 *statp = block.b_status;
83 return 0;
84 }
85
86 /* Okay, we were interrupted. Cancel the pending request
87 * unless the server has rebooted.
88 */
89 if (pstate == host->h_state && (err = nlmclnt_cancel(host, fl)) < 0)
90 printk(KERN_NOTICE
91 "lockd: CANCEL call failed (errno %d)\n", -err);
92
93 return -ERESTARTSYS;
94 }
95
96 /*
97 * The server lockd has called us back to tell us the lock was granted
98 */
99 u32
100 nlmclnt_grant(struct nlm_lock *lock)
101 {
102 struct nlm_wait *block;
103
104 /*
105 * Look up blocked request based on arguments.
106 * Warning: must not use cookie to match it!
107 */
108 for (block = nlm_blocked; block; block = block->b_next) {
109 if (nlm_compare_locks(block->b_lock, &lock->fl))
110 break;
111 }
112
113 /* Ooops, no blocked request found. */
114 if (block == NULL)
115 return nlm_lck_denied;
116
117 /* Alright, we found the lock. Set the return status and
118 * wake up the caller.
119 */
120 block->b_status = NLM_LCK_GRANTED;
121 wake_up(&block->b_wait);
122
123 return nlm_granted;
124 }
125
126 /*
127 * The following procedures deal with the recovery of locks after a
128 * server crash.
129 */
130
131 /*
132 * Mark the locks for reclaiming.
133 * FIXME: In 2.5 we don't want to iterate through any global file_lock_list.
134 * Maintain NLM lock reclaiming lists in the nlm_host instead.
135 */
136 static
137 void nlmclnt_mark_reclaim(struct nlm_host *host)
138 {
139 struct file_lock *fl;
140 struct inode *inode;
141 struct list_head *tmp;
142
143 list_for_each(tmp, &file_lock_list) {
144 fl = list_entry(tmp, struct file_lock, fl_link);
145
146 inode = fl->fl_file->f_dentry->d_inode;
147 if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
148 continue;
149 if (fl->fl_u.nfs_fl.owner->host != host)
150 continue;
151 if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED))
152 continue;
153 fl->fl_u.nfs_fl.flags |= NFS_LCK_RECLAIM;
154 }
155 }
156
157 /*
158 * Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number,
159 * that we mark locks for reclaiming, and that we bump the pseudo NSM state.
160 */
161 static inline
162 void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate)
163 {
164 host->h_monitored = 0;
165 host->h_nsmstate = newstate;
166 host->h_state++;
167 host->h_nextrebind = 0;
168 nlm_rebind_host(host);
169 nlmclnt_mark_reclaim(host);
170 dprintk("NLM: reclaiming locks for host %s", host->h_name);
171 }
172
173 /*
174 * Reclaim all locks on server host. We do this by spawning a separate
175 * reclaimer thread.
176 */
177 void
178 nlmclnt_recovery(struct nlm_host *host, u32 newstate)
179 {
180 if (host->h_reclaiming++) {
181 if (host->h_nsmstate == newstate)
182 return;
183 nlmclnt_prepare_reclaim(host, newstate);
184 } else {
185 nlmclnt_prepare_reclaim(host, newstate);
186 nlm_get_host(host);
187 __module_get(THIS_MODULE);
188 if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
189 module_put(THIS_MODULE);
190 }
191 }
192
193 static int
194 reclaimer(void *ptr)
195 {
196 struct nlm_host *host = (struct nlm_host *) ptr;
197 struct nlm_wait *block;
198 struct list_head *tmp;
199 struct file_lock *fl;
200 struct inode *inode;
201
202 daemonize("%s-reclaim", host->h_name);
203 allow_signal(SIGKILL);
204
205 /* This one ensures that our parent doesn't terminate while the
206 * reclaim is in progress */
207 lock_kernel();
208 lockd_up();
209
210 /* First, reclaim all locks that have been marked. */
211 restart:
212 list_for_each(tmp, &file_lock_list) {
213 fl = list_entry(tmp, struct file_lock, fl_link);
214
215 inode = fl->fl_file->f_dentry->d_inode;
216 if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
217 continue;
218 if (fl->fl_u.nfs_fl.owner->host != host)
219 continue;
220 if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM))
221 continue;
222
223 fl->fl_u.nfs_fl.flags &= ~NFS_LCK_RECLAIM;
224 nlmclnt_reclaim(host, fl);
225 if (signalled())
226 break;
227 goto restart;
228 }
229
230 host->h_reclaiming = 0;
231
232 /* Now, wake up all processes that sleep on a blocked lock */
233 for (block = nlm_blocked; block; block = block->b_next) {
234 if (block->b_host == host) {
235 block->b_status = NLM_LCK_DENIED_GRACE_PERIOD;
236 wake_up(&block->b_wait);
237 }
238 }
239
240 /* Release host handle after use */
241 nlm_release_host(host);
242 lockd_down();
243 unlock_kernel();
244 module_put_and_exit(0);
245 }
246
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