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/addr.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 */
24static 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 */
34struct 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
43static LIST_HEAD(nlm_blocked);
44static 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 */
53struct 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 goto out_nohost;
69 if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL)
70 goto out_nobind;
71
72 host->h_nlmclnt_ops = nlm_init->nlmclnt_ops;
73 return host;
74out_nobind:
75 nlmclnt_release_host(host);
76out_nohost:
77 lockd_down(nlm_init->net);
78 return ERR_PTR(-ENOLCK);
79}
80EXPORT_SYMBOL_GPL(nlmclnt_init);
81
82/**
83 * nlmclnt_done - Release resources allocated by nlmclnt_init()
84 * @host: nlm_host structure reserved by nlmclnt_init()
85 *
86 */
87void nlmclnt_done(struct nlm_host *host)
88{
89 struct net *net = host->net;
90
91 nlmclnt_release_host(host);
92 lockd_down(net);
93}
94EXPORT_SYMBOL_GPL(nlmclnt_done);
95
96/*
97 * Queue up a lock for blocking so that the GRANTED request can see it
98 */
99struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
100{
101 struct nlm_wait *block;
102
103 block = kmalloc(sizeof(*block), GFP_KERNEL);
104 if (block != NULL) {
105 block->b_host = host;
106 block->b_lock = fl;
107 init_waitqueue_head(&block->b_wait);
108 block->b_status = nlm_lck_blocked;
109
110 spin_lock(&nlm_blocked_lock);
111 list_add(&block->b_list, &nlm_blocked);
112 spin_unlock(&nlm_blocked_lock);
113 }
114 return block;
115}
116
117void nlmclnt_finish_block(struct nlm_wait *block)
118{
119 if (block == NULL)
120 return;
121 spin_lock(&nlm_blocked_lock);
122 list_del(&block->b_list);
123 spin_unlock(&nlm_blocked_lock);
124 kfree(block);
125}
126
127/*
128 * Block on a lock
129 */
130int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
131{
132 long ret;
133
134 /* A borken server might ask us to block even if we didn't
135 * request it. Just say no!
136 */
137 if (block == NULL)
138 return -EAGAIN;
139
140 /* Go to sleep waiting for GRANT callback. Some servers seem
141 * to lose callbacks, however, so we're going to poll from
142 * time to time just to make sure.
143 *
144 * For now, the retry frequency is pretty high; normally
145 * a 1 minute timeout would do. See the comment before
146 * nlmclnt_lock for an explanation.
147 */
148 ret = wait_event_interruptible_timeout(block->b_wait,
149 block->b_status != nlm_lck_blocked,
150 timeout);
151 if (ret < 0)
152 return -ERESTARTSYS;
153 /* Reset the lock status after a server reboot so we resend */
154 if (block->b_status == nlm_lck_denied_grace_period)
155 block->b_status = nlm_lck_blocked;
156 req->a_res.status = block->b_status;
157 return 0;
158}
159
160/*
161 * The server lockd has called us back to tell us the lock was granted
162 */
163__be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
164{
165 const struct file_lock *fl = &lock->fl;
166 const struct nfs_fh *fh = &lock->fh;
167 struct nlm_wait *block;
168 __be32 res = nlm_lck_denied;
169
170 /*
171 * Look up blocked request based on arguments.
172 * Warning: must not use cookie to match it!
173 */
174 spin_lock(&nlm_blocked_lock);
175 list_for_each_entry(block, &nlm_blocked, b_list) {
176 struct file_lock *fl_blocked = block->b_lock;
177
178 if (fl_blocked->fl_start != fl->fl_start)
179 continue;
180 if (fl_blocked->fl_end != fl->fl_end)
181 continue;
182 /*
183 * Careful! The NLM server will return the 32-bit "pid" that
184 * we put on the wire: in this case the lockowner "pid".
185 */
186 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
187 continue;
188 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
189 continue;
190 if (nfs_compare_fh(NFS_FH(locks_inode(fl_blocked->fl_file)), fh) != 0)
191 continue;
192 /* Alright, we found a lock. Set the return status
193 * and wake up the caller
194 */
195 block->b_status = nlm_granted;
196 wake_up(&block->b_wait);
197 res = nlm_granted;
198 }
199 spin_unlock(&nlm_blocked_lock);
200 return res;
201}
202
203/*
204 * The following procedures deal with the recovery of locks after a
205 * server crash.
206 */
207
208/*
209 * Reclaim all locks on server host. We do this by spawning a separate
210 * reclaimer thread.
211 */
212void
213nlmclnt_recovery(struct nlm_host *host)
214{
215 struct task_struct *task;
216
217 if (!host->h_reclaiming++) {
218 nlm_get_host(host);
219 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
220 if (IS_ERR(task))
221 printk(KERN_ERR "lockd: unable to spawn reclaimer "
222 "thread. Locks for %s won't be reclaimed! "
223 "(%ld)\n", host->h_name, PTR_ERR(task));
224 }
225}
226
227static int
228reclaimer(void *ptr)
229{
230 struct nlm_host *host = (struct nlm_host *) ptr;
231 struct nlm_wait *block;
232 struct nlm_rqst *req;
233 struct file_lock *fl, *next;
234 u32 nsmstate;
235 struct net *net = host->net;
236
237 req = kmalloc(sizeof(*req), GFP_KERNEL);
238 if (!req)
239 return 0;
240
241 allow_signal(SIGKILL);
242
243 down_write(&host->h_rwsem);
244 lockd_up(net); /* note: this cannot fail as lockd is already running */
245
246 dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
247
248restart:
249 nsmstate = host->h_nsmstate;
250
251 /* Force a portmap getport - the peer's lockd will
252 * most likely end up on a different port.
253 */
254 host->h_nextrebind = jiffies;
255 nlm_rebind_host(host);
256
257 /* First, reclaim all locks that have been granted. */
258 list_splice_init(&host->h_granted, &host->h_reclaim);
259 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
260 list_del_init(&fl->fl_u.nfs_fl.list);
261
262 /*
263 * sending this thread a SIGKILL will result in any unreclaimed
264 * locks being removed from the h_granted list. This means that
265 * the kernel will not attempt to reclaim them again if a new
266 * reclaimer thread is spawned for this host.
267 */
268 if (signalled())
269 continue;
270 if (nlmclnt_reclaim(host, fl, req) != 0)
271 continue;
272 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
273 if (host->h_nsmstate != nsmstate) {
274 /* Argh! The server rebooted again! */
275 goto restart;
276 }
277 }
278
279 host->h_reclaiming = 0;
280 up_write(&host->h_rwsem);
281 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
282
283 /* Now, wake up all processes that sleep on a blocked lock */
284 spin_lock(&nlm_blocked_lock);
285 list_for_each_entry(block, &nlm_blocked, b_list) {
286 if (block->b_host == host) {
287 block->b_status = nlm_lck_denied_grace_period;
288 wake_up(&block->b_wait);
289 }
290 }
291 spin_unlock(&nlm_blocked_lock);
292
293 /* Release host handle after use */
294 nlmclnt_release_host(host);
295 lockd_down(net);
296 kfree(req);
297 return 0;
298}
299