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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 */
28static int reclaimer(void *ptr);
29
30/*
31 * The following functions handle blocking and granting from the
32 * client perspective.
33 */
34
35static LIST_HEAD(nlm_blocked);
36static 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 */
45struct 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;
66out_nobind:
67 nlmclnt_release_host(host);
68out_nohost:
69 lockd_down(net: nlm_init->net);
70 return ERR_PTR(error: -ENOLCK);
71}
72EXPORT_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 */
79void nlmclnt_done(struct nlm_host *host)
80{
81 struct net *net = host->net;
82
83 nlmclnt_release_host(host);
84 lockd_down(net);
85}
86EXPORT_SYMBOL_GPL(nlmclnt_done);
87
88void 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
96struct rpc_clnt *nlmclnt_rpc_clnt(struct nlm_host *host)
97{
98 return host->h_rpcclnt;
99}
100EXPORT_SYMBOL_GPL(nlmclnt_rpc_clnt);
101
102/*
103 * Queue up a lock for blocking so that the GRANTED request can see it
104 */
105void 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 */
129int 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->c.flc_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 */
211void
212nlmclnt_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
226static int
227reclaimer(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(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
247restart:
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

source code of linux/fs/lockd/clntlock.c