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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 | */ |
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 | */ |
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 *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(nlm_addr(block->b_host), 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 | struct task_struct *task; |
196 | |
197 | if (!host->h_reclaiming++) { |
198 | nlm_get_host(host); |
199 | task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name); |
200 | if (IS_ERR(task)) |
201 | printk(KERN_ERR "lockd: unable to spawn reclaimer " |
202 | "thread. Locks for %s won't be reclaimed! " |
203 | "(%ld)\n", host->h_name, PTR_ERR(task)); |
204 | } |
205 | } |
206 | |
207 | static int |
208 | reclaimer(void *ptr) |
209 | { |
210 | struct nlm_host *host = (struct nlm_host *) ptr; |
211 | struct nlm_wait *block; |
212 | struct file_lock *fl, *next; |
213 | u32 nsmstate; |
214 | |
215 | allow_signal(SIGKILL); |
216 | |
217 | down_write(&host->h_rwsem); |
218 | |
219 | /* This one ensures that our parent doesn't terminate while the |
220 | * reclaim is in progress */ |
221 | lock_kernel(); |
222 | lockd_up(); /* note: this cannot fail as lockd is already running */ |
223 | |
224 | dprintk("lockd: reclaiming locks for host %s\n", host->h_name); |
225 | |
226 | restart: |
227 | nsmstate = host->h_nsmstate; |
228 | |
229 | /* Force a portmap getport - the peer's lockd will |
230 | * most likely end up on a different port. |
231 | */ |
232 | host->h_nextrebind = jiffies; |
233 | nlm_rebind_host(host); |
234 | |
235 | /* First, reclaim all locks that have been granted. */ |
236 | list_splice_init(&host->h_granted, &host->h_reclaim); |
237 | list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { |
238 | list_del_init(&fl->fl_u.nfs_fl.list); |
239 | |
240 | /* |
241 | * sending this thread a SIGKILL will result in any unreclaimed |
242 | * locks being removed from the h_granted list. This means that |
243 | * the kernel will not attempt to reclaim them again if a new |
244 | * reclaimer thread is spawned for this host. |
245 | */ |
246 | if (signalled()) |
247 | continue; |
248 | if (nlmclnt_reclaim(host, fl) != 0) |
249 | continue; |
250 | list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); |
251 | if (host->h_nsmstate != nsmstate) { |
252 | /* Argh! The server rebooted again! */ |
253 | goto restart; |
254 | } |
255 | } |
256 | |
257 | host->h_reclaiming = 0; |
258 | up_write(&host->h_rwsem); |
259 | dprintk("NLM: done reclaiming locks for host %s\n", host->h_name); |
260 | |
261 | /* Now, wake up all processes that sleep on a blocked lock */ |
262 | list_for_each_entry(block, &nlm_blocked, b_list) { |
263 | if (block->b_host == host) { |
264 | block->b_status = nlm_lck_denied_grace_period; |
265 | wake_up(&block->b_wait); |
266 | } |
267 | } |
268 | |
269 | /* Release host handle after use */ |
270 | nlm_release_host(host); |
271 | lockd_down(); |
272 | unlock_kernel(); |
273 | return 0; |
274 | } |
275 |
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