1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * linux/fs/lockd/clntlock.c |
4 | * |
5 | * Lock handling for the client side NLM implementation |
6 | * |
7 | * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de> |
8 | */ |
9 | |
10 | #include <linux/module.h> |
11 | #include <linux/types.h> |
12 | #include <linux/slab.h> |
13 | #include <linux/time.h> |
14 | #include <linux/nfs_fs.h> |
15 | #include <linux/sunrpc/addr.h> |
16 | #include <linux/sunrpc/svc.h> |
17 | #include <linux/sunrpc/svc_xprt.h> |
18 | #include <linux/lockd/lockd.h> |
19 | #include <linux/kthread.h> |
20 | |
21 | #include "trace.h" |
22 | |
23 | #define NLMDBG_FACILITY NLMDBG_CLIENT |
24 | |
25 | /* |
26 | * Local function prototypes |
27 | */ |
28 | static int reclaimer(void *ptr); |
29 | |
30 | /* |
31 | * The following functions handle blocking and granting from the |
32 | * client perspective. |
33 | */ |
34 | |
35 | static LIST_HEAD(nlm_blocked); |
36 | static DEFINE_SPINLOCK(nlm_blocked_lock); |
37 | |
38 | /** |
39 | * nlmclnt_init - Set up per-NFS mount point lockd data structures |
40 | * @nlm_init: pointer to arguments structure |
41 | * |
42 | * Returns pointer to an appropriate nlm_host struct, |
43 | * or an ERR_PTR value. |
44 | */ |
45 | struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init) |
46 | { |
47 | struct nlm_host *host; |
48 | u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4; |
49 | int status; |
50 | |
51 | status = lockd_up(net: nlm_init->net, cred: nlm_init->cred); |
52 | if (status < 0) |
53 | return ERR_PTR(error: status); |
54 | |
55 | host = nlmclnt_lookup_host(sap: nlm_init->address, salen: nlm_init->addrlen, |
56 | protocol: nlm_init->protocol, version: nlm_version, |
57 | hostname: nlm_init->hostname, noresvport: nlm_init->noresvport, |
58 | net: nlm_init->net, cred: nlm_init->cred); |
59 | if (host == NULL) |
60 | goto out_nohost; |
61 | if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL) |
62 | goto out_nobind; |
63 | |
64 | host->h_nlmclnt_ops = nlm_init->nlmclnt_ops; |
65 | return host; |
66 | out_nobind: |
67 | nlmclnt_release_host(host); |
68 | out_nohost: |
69 | lockd_down(net: nlm_init->net); |
70 | return ERR_PTR(error: -ENOLCK); |
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 | struct net *net = host->net; |
82 | |
83 | nlmclnt_release_host(host); |
84 | lockd_down(net); |
85 | } |
86 | EXPORT_SYMBOL_GPL(nlmclnt_done); |
87 | |
88 | void nlmclnt_prepare_block(struct nlm_wait *block, struct nlm_host *host, struct file_lock *fl) |
89 | { |
90 | block->b_host = host; |
91 | block->b_lock = fl; |
92 | init_waitqueue_head(&block->b_wait); |
93 | block->b_status = nlm_lck_blocked; |
94 | } |
95 | |
96 | struct rpc_clnt *nlmclnt_rpc_clnt(struct nlm_host *host) |
97 | { |
98 | return host->h_rpcclnt; |
99 | } |
100 | EXPORT_SYMBOL_GPL(nlmclnt_rpc_clnt); |
101 | |
102 | /* |
103 | * Queue up a lock for blocking so that the GRANTED request can see it |
104 | */ |
105 | void nlmclnt_queue_block(struct nlm_wait *block) |
106 | { |
107 | spin_lock(lock: &nlm_blocked_lock); |
108 | list_add(new: &block->b_list, head: &nlm_blocked); |
109 | spin_unlock(lock: &nlm_blocked_lock); |
110 | } |
111 | |
112 | /* |
113 | * Dequeue the block and return its final status |
114 | */ |
115 | __be32 nlmclnt_dequeue_block(struct nlm_wait *block) |
116 | { |
117 | __be32 status; |
118 | |
119 | spin_lock(lock: &nlm_blocked_lock); |
120 | list_del(entry: &block->b_list); |
121 | status = block->b_status; |
122 | spin_unlock(lock: &nlm_blocked_lock); |
123 | return status; |
124 | } |
125 | |
126 | /* |
127 | * Block on a lock |
128 | */ |
129 | int nlmclnt_wait(struct nlm_wait *block, struct nlm_rqst *req, long timeout) |
130 | { |
131 | long ret; |
132 | |
133 | /* A borken server might ask us to block even if we didn't |
134 | * request it. Just say no! |
135 | */ |
136 | if (block == NULL) |
137 | return -EAGAIN; |
138 | |
139 | /* Go to sleep waiting for GRANT callback. Some servers seem |
140 | * to lose callbacks, however, so we're going to poll from |
141 | * time to time just to make sure. |
142 | * |
143 | * For now, the retry frequency is pretty high; normally |
144 | * a 1 minute timeout would do. See the comment before |
145 | * nlmclnt_lock for an explanation. |
146 | */ |
147 | ret = wait_event_interruptible_timeout(block->b_wait, |
148 | block->b_status != nlm_lck_blocked, |
149 | timeout); |
150 | if (ret < 0) |
151 | return -ERESTARTSYS; |
152 | /* Reset the lock status after a server reboot so we resend */ |
153 | if (block->b_status == nlm_lck_denied_grace_period) |
154 | block->b_status = nlm_lck_blocked; |
155 | return 0; |
156 | } |
157 | |
158 | /* |
159 | * The server lockd has called us back to tell us the lock was granted |
160 | */ |
161 | __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock) |
162 | { |
163 | const struct file_lock *fl = &lock->fl; |
164 | const struct nfs_fh *fh = &lock->fh; |
165 | struct nlm_wait *block; |
166 | __be32 res = nlm_lck_denied; |
167 | |
168 | /* |
169 | * Look up blocked request based on arguments. |
170 | * Warning: must not use cookie to match it! |
171 | */ |
172 | spin_lock(lock: &nlm_blocked_lock); |
173 | list_for_each_entry(block, &nlm_blocked, b_list) { |
174 | struct file_lock *fl_blocked = block->b_lock; |
175 | |
176 | if (fl_blocked->fl_start != fl->fl_start) |
177 | continue; |
178 | if (fl_blocked->fl_end != fl->fl_end) |
179 | continue; |
180 | /* |
181 | * Careful! The NLM server will return the 32-bit "pid" that |
182 | * we put on the wire: in this case the lockowner "pid". |
183 | */ |
184 | if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) |
185 | continue; |
186 | if (!rpc_cmp_addr(sap1: nlm_addr(host: block->b_host), sap2: addr)) |
187 | continue; |
188 | if (nfs_compare_fh(a: NFS_FH(inode: file_inode(f: fl_blocked->fl_file)), b: fh) != 0) |
189 | continue; |
190 | /* Alright, we found a lock. Set the return status |
191 | * and wake up the caller |
192 | */ |
193 | block->b_status = nlm_granted; |
194 | wake_up(&block->b_wait); |
195 | res = nlm_granted; |
196 | } |
197 | spin_unlock(lock: &nlm_blocked_lock); |
198 | trace_nlmclnt_grant(lock, addr, addrlen: svc_addr_len(sa: addr), status: res); |
199 | return res; |
200 | } |
201 | |
202 | /* |
203 | * The following procedures deal with the recovery of locks after a |
204 | * server crash. |
205 | */ |
206 | |
207 | /* |
208 | * Reclaim all locks on server host. We do this by spawning a separate |
209 | * reclaimer thread. |
210 | */ |
211 | void |
212 | nlmclnt_recovery(struct nlm_host *host) |
213 | { |
214 | struct task_struct *task; |
215 | |
216 | if (!host->h_reclaiming++) { |
217 | nlm_get_host(host); |
218 | task = kthread_run(reclaimer, host, "%s-reclaim" , host->h_name); |
219 | if (IS_ERR(ptr: task)) |
220 | printk(KERN_ERR "lockd: unable to spawn reclaimer " |
221 | "thread. Locks for %s won't be reclaimed! " |
222 | "(%ld)\n" , host->h_name, PTR_ERR(task)); |
223 | } |
224 | } |
225 | |
226 | static int |
227 | reclaimer(void *ptr) |
228 | { |
229 | struct nlm_host *host = (struct nlm_host *) ptr; |
230 | struct nlm_wait *block; |
231 | struct nlm_rqst *req; |
232 | struct file_lock *fl, *next; |
233 | u32 nsmstate; |
234 | struct net *net = host->net; |
235 | |
236 | req = kmalloc(size: sizeof(*req), GFP_KERNEL); |
237 | if (!req) |
238 | return 0; |
239 | |
240 | allow_signal(SIGKILL); |
241 | |
242 | down_write(sem: &host->h_rwsem); |
243 | lockd_up(net, NULL); /* note: this cannot fail as lockd is already running */ |
244 | |
245 | dprintk("lockd: reclaiming locks for host %s\n" , host->h_name); |
246 | |
247 | restart: |
248 | nsmstate = host->h_nsmstate; |
249 | |
250 | /* Force a portmap getport - the peer's lockd will |
251 | * most likely end up on a different port. |
252 | */ |
253 | host->h_nextrebind = jiffies; |
254 | nlm_rebind_host(host); |
255 | |
256 | /* First, reclaim all locks that have been granted. */ |
257 | list_splice_init(list: &host->h_granted, head: &host->h_reclaim); |
258 | list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { |
259 | list_del_init(entry: &fl->fl_u.nfs_fl.list); |
260 | |
261 | /* |
262 | * sending this thread a SIGKILL will result in any unreclaimed |
263 | * locks being removed from the h_granted list. This means that |
264 | * the kernel will not attempt to reclaim them again if a new |
265 | * reclaimer thread is spawned for this host. |
266 | */ |
267 | if (signalled()) |
268 | continue; |
269 | if (nlmclnt_reclaim(host, fl, req) != 0) |
270 | continue; |
271 | list_add_tail(new: &fl->fl_u.nfs_fl.list, head: &host->h_granted); |
272 | if (host->h_nsmstate != nsmstate) { |
273 | /* Argh! The server rebooted again! */ |
274 | goto restart; |
275 | } |
276 | } |
277 | |
278 | host->h_reclaiming = 0; |
279 | up_write(sem: &host->h_rwsem); |
280 | dprintk("NLM: done reclaiming locks for host %s\n" , host->h_name); |
281 | |
282 | /* Now, wake up all processes that sleep on a blocked lock */ |
283 | spin_lock(lock: &nlm_blocked_lock); |
284 | list_for_each_entry(block, &nlm_blocked, b_list) { |
285 | if (block->b_host == host) { |
286 | block->b_status = nlm_lck_denied_grace_period; |
287 | wake_up(&block->b_wait); |
288 | } |
289 | } |
290 | spin_unlock(lock: &nlm_blocked_lock); |
291 | |
292 | /* Release host handle after use */ |
293 | nlmclnt_release_host(host); |
294 | lockd_down(net); |
295 | kfree(objp: req); |
296 | return 0; |
297 | } |
298 | |