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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/slab.h>
12#include <linux/time.h>
13#include <linux/nfs_fs.h>
14#include <linux/sunrpc/clnt.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 lockd_down(nlm_init->net);
69 return ERR_PTR(-ENOLCK);
70 }
71
72 return host;
73}
74EXPORT_SYMBOL_GPL(nlmclnt_init);
75
76/**
77 * nlmclnt_done - Release resources allocated by nlmclnt_init()
78 * @host: nlm_host structure reserved by nlmclnt_init()
79 *
80 */
81void nlmclnt_done(struct nlm_host *host)
82{
83 struct net *net = host->net;
84
85 nlmclnt_release_host(host);
86 lockd_down(net);
87}
88EXPORT_SYMBOL_GPL(nlmclnt_done);
89
90/*
91 * Queue up a lock for blocking so that the GRANTED request can see it
92 */
93struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
94{
95 struct nlm_wait *block;
96
97 block = kmalloc(sizeof(*block), GFP_KERNEL);
98 if (block != NULL) {
99 block->b_host = host;
100 block->b_lock = fl;
101 init_waitqueue_head(&block->b_wait);
102 block->b_status = nlm_lck_blocked;
103
104 spin_lock(&nlm_blocked_lock);
105 list_add(&block->b_list, &nlm_blocked);
106 spin_unlock(&nlm_blocked_lock);
107 }
108 return block;
109}
110
111void nlmclnt_finish_block(struct nlm_wait *block)
112{
113 if (block == NULL)
114 return;
115 spin_lock(&nlm_blocked_lock);
116 list_del(&block->b_list);
117 spin_unlock(&nlm_blocked_lock);
118 kfree(block);
119}
120
121/*
122 * Block on a lock
123 */
124int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
125{
126 long ret;
127
128 /* A borken server might ask us to block even if we didn't
129 * request it. Just say no!
130 */
131 if (block == NULL)
132 return -EAGAIN;
133
134 /* Go to sleep waiting for GRANT callback. Some servers seem
135 * to lose callbacks, however, so we're going to poll from
136 * time to time just to make sure.
137 *
138 * For now, the retry frequency is pretty high; normally
139 * a 1 minute timeout would do. See the comment before
140 * nlmclnt_lock for an explanation.
141 */
142 ret = wait_event_interruptible_timeout(block->b_wait,
143 block->b_status != nlm_lck_blocked,
144 timeout);
145 if (ret < 0)
146 return -ERESTARTSYS;
147 req->a_res.status = block->b_status;
148 return 0;
149}
150
151/*
152 * The server lockd has called us back to tell us the lock was granted
153 */
154__be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
155{
156 const struct file_lock *fl = &lock->fl;
157 const struct nfs_fh *fh = &lock->fh;
158 struct nlm_wait *block;
159 __be32 res = nlm_lck_denied;
160
161 /*
162 * Look up blocked request based on arguments.
163 * Warning: must not use cookie to match it!
164 */
165 spin_lock(&nlm_blocked_lock);
166 list_for_each_entry(block, &nlm_blocked, b_list) {
167 struct file_lock *fl_blocked = block->b_lock;
168
169 if (fl_blocked->fl_start != fl->fl_start)
170 continue;
171 if (fl_blocked->fl_end != fl->fl_end)
172 continue;
173 /*
174 * Careful! The NLM server will return the 32-bit "pid" that
175 * we put on the wire: in this case the lockowner "pid".
176 */
177 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
178 continue;
179 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
180 continue;
181 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
182 continue;
183 /* Alright, we found a lock. Set the return status
184 * and wake up the caller
185 */
186 block->b_status = nlm_granted;
187 wake_up(&block->b_wait);
188 res = nlm_granted;
189 }
190 spin_unlock(&nlm_blocked_lock);
191 return res;
192}
193
194/*
195 * The following procedures deal with the recovery of locks after a
196 * server crash.
197 */
198
199/*
200 * Reclaim all locks on server host. We do this by spawning a separate
201 * reclaimer thread.
202 */
203void
204nlmclnt_recovery(struct nlm_host *host)
205{
206 struct task_struct *task;
207
208 if (!host->h_reclaiming++) {
209 nlm_get_host(host);
210 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
211 if (IS_ERR(task))
212 printk(KERN_ERR "lockd: unable to spawn reclaimer "
213 "thread. Locks for %s won't be reclaimed! "
214 "(%ld)\n", host->h_name, PTR_ERR(task));
215 }
216}
217
218static int
219reclaimer(void *ptr)
220{
221 struct nlm_host *host = (struct nlm_host *) ptr;
222 struct nlm_wait *block;
223 struct file_lock *fl, *next;
224 u32 nsmstate;
225 struct net *net = host->net;
226
227 allow_signal(SIGKILL);
228
229 down_write(&host->h_rwsem);
230 lockd_up(net); /* note: this cannot fail as lockd is already running */
231
232 dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
233
234restart:
235 nsmstate = host->h_nsmstate;
236
237 /* Force a portmap getport - the peer's lockd will
238 * most likely end up on a different port.
239 */
240 host->h_nextrebind = jiffies;
241 nlm_rebind_host(host);
242
243 /* First, reclaim all locks that have been granted. */
244 list_splice_init(&host->h_granted, &host->h_reclaim);
245 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
246 list_del_init(&fl->fl_u.nfs_fl.list);
247
248 /*
249 * sending this thread a SIGKILL will result in any unreclaimed
250 * locks being removed from the h_granted list. This means that
251 * the kernel will not attempt to reclaim them again if a new
252 * reclaimer thread is spawned for this host.
253 */
254 if (signalled())
255 continue;
256 if (nlmclnt_reclaim(host, fl) != 0)
257 continue;
258 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
259 if (host->h_nsmstate != nsmstate) {
260 /* Argh! The server rebooted again! */
261 goto restart;
262 }
263 }
264
265 host->h_reclaiming = 0;
266 up_write(&host->h_rwsem);
267 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
268
269 /* Now, wake up all processes that sleep on a blocked lock */
270 spin_lock(&nlm_blocked_lock);
271 list_for_each_entry(block, &nlm_blocked, b_list) {
272 if (block->b_host == host) {
273 block->b_status = nlm_lck_denied_grace_period;
274 wake_up(&block->b_wait);
275 }
276 }
277 spin_unlock(&nlm_blocked_lock);
278
279 /* Release host handle after use */
280 nlmclnt_release_host(host);
281 lockd_down(net);
282 return 0;
283}
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/lockd/lockd.h>
18#include <linux/kthread.h>
19
20#define NLMDBG_FACILITY NLMDBG_CLIENT
21
22/*
23 * Local function prototypes
24 */
25static int reclaimer(void *ptr);
26
27/*
28 * The following functions handle blocking and granting from the
29 * client perspective.
30 */
31
32/*
33 * This is the representation of a blocked client lock.
34 */
35struct nlm_wait {
36 struct list_head b_list; /* linked list */
37 wait_queue_head_t b_wait; /* where to wait on */
38 struct nlm_host * b_host;
39 struct file_lock * b_lock; /* local file lock */
40 unsigned short b_reclaim; /* got to reclaim lock */
41 __be32 b_status; /* grant callback status */
42};
43
44static LIST_HEAD(nlm_blocked);
45static DEFINE_SPINLOCK(nlm_blocked_lock);
46
47/**
48 * nlmclnt_init - Set up per-NFS mount point lockd data structures
49 * @nlm_init: pointer to arguments structure
50 *
51 * Returns pointer to an appropriate nlm_host struct,
52 * or an ERR_PTR value.
53 */
54struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
55{
56 struct nlm_host *host;
57 u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
58 int status;
59
60 status = lockd_up(nlm_init->net, nlm_init->cred);
61 if (status < 0)
62 return ERR_PTR(status);
63
64 host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen,
65 nlm_init->protocol, nlm_version,
66 nlm_init->hostname, nlm_init->noresvport,
67 nlm_init->net, nlm_init->cred);
68 if (host == NULL)
69 goto out_nohost;
70 if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL)
71 goto out_nobind;
72
73 host->h_nlmclnt_ops = nlm_init->nlmclnt_ops;
74 return host;
75out_nobind:
76 nlmclnt_release_host(host);
77out_nohost:
78 lockd_down(nlm_init->net);
79 return ERR_PTR(-ENOLCK);
80}
81EXPORT_SYMBOL_GPL(nlmclnt_init);
82
83/**
84 * nlmclnt_done - Release resources allocated by nlmclnt_init()
85 * @host: nlm_host structure reserved by nlmclnt_init()
86 *
87 */
88void nlmclnt_done(struct nlm_host *host)
89{
90 struct net *net = host->net;
91
92 nlmclnt_release_host(host);
93 lockd_down(net);
94}
95EXPORT_SYMBOL_GPL(nlmclnt_done);
96
97/*
98 * Queue up a lock for blocking so that the GRANTED request can see it
99 */
100struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
101{
102 struct nlm_wait *block;
103
104 block = kmalloc(sizeof(*block), GFP_KERNEL);
105 if (block != NULL) {
106 block->b_host = host;
107 block->b_lock = fl;
108 init_waitqueue_head(&block->b_wait);
109 block->b_status = nlm_lck_blocked;
110
111 spin_lock(&nlm_blocked_lock);
112 list_add(&block->b_list, &nlm_blocked);
113 spin_unlock(&nlm_blocked_lock);
114 }
115 return block;
116}
117
118void nlmclnt_finish_block(struct nlm_wait *block)
119{
120 if (block == NULL)
121 return;
122 spin_lock(&nlm_blocked_lock);
123 list_del(&block->b_list);
124 spin_unlock(&nlm_blocked_lock);
125 kfree(block);
126}
127
128/*
129 * Block on a lock
130 */
131int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
132{
133 long ret;
134
135 /* A borken server might ask us to block even if we didn't
136 * request it. Just say no!
137 */
138 if (block == NULL)
139 return -EAGAIN;
140
141 /* Go to sleep waiting for GRANT callback. Some servers seem
142 * to lose callbacks, however, so we're going to poll from
143 * time to time just to make sure.
144 *
145 * For now, the retry frequency is pretty high; normally
146 * a 1 minute timeout would do. See the comment before
147 * nlmclnt_lock for an explanation.
148 */
149 ret = wait_event_interruptible_timeout(block->b_wait,
150 block->b_status != nlm_lck_blocked,
151 timeout);
152 if (ret < 0)
153 return -ERESTARTSYS;
154 /* Reset the lock status after a server reboot so we resend */
155 if (block->b_status == nlm_lck_denied_grace_period)
156 block->b_status = nlm_lck_blocked;
157 req->a_res.status = block->b_status;
158 return 0;
159}
160
161/*
162 * The server lockd has called us back to tell us the lock was granted
163 */
164__be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
165{
166 const struct file_lock *fl = &lock->fl;
167 const struct nfs_fh *fh = &lock->fh;
168 struct nlm_wait *block;
169 __be32 res = nlm_lck_denied;
170
171 /*
172 * Look up blocked request based on arguments.
173 * Warning: must not use cookie to match it!
174 */
175 spin_lock(&nlm_blocked_lock);
176 list_for_each_entry(block, &nlm_blocked, b_list) {
177 struct file_lock *fl_blocked = block->b_lock;
178
179 if (fl_blocked->fl_start != fl->fl_start)
180 continue;
181 if (fl_blocked->fl_end != fl->fl_end)
182 continue;
183 /*
184 * Careful! The NLM server will return the 32-bit "pid" that
185 * we put on the wire: in this case the lockowner "pid".
186 */
187 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
188 continue;
189 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
190 continue;
191 if (nfs_compare_fh(NFS_FH(locks_inode(fl_blocked->fl_file)), fh) != 0)
192 continue;
193 /* Alright, we found a lock. Set the return status
194 * and wake up the caller
195 */
196 block->b_status = nlm_granted;
197 wake_up(&block->b_wait);
198 res = nlm_granted;
199 }
200 spin_unlock(&nlm_blocked_lock);
201 return res;
202}
203
204/*
205 * The following procedures deal with the recovery of locks after a
206 * server crash.
207 */
208
209/*
210 * Reclaim all locks on server host. We do this by spawning a separate
211 * reclaimer thread.
212 */
213void
214nlmclnt_recovery(struct nlm_host *host)
215{
216 struct task_struct *task;
217
218 if (!host->h_reclaiming++) {
219 nlm_get_host(host);
220 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
221 if (IS_ERR(task))
222 printk(KERN_ERR "lockd: unable to spawn reclaimer "
223 "thread. Locks for %s won't be reclaimed! "
224 "(%ld)\n", host->h_name, PTR_ERR(task));
225 }
226}
227
228static int
229reclaimer(void *ptr)
230{
231 struct nlm_host *host = (struct nlm_host *) ptr;
232 struct nlm_wait *block;
233 struct nlm_rqst *req;
234 struct file_lock *fl, *next;
235 u32 nsmstate;
236 struct net *net = host->net;
237
238 req = kmalloc(sizeof(*req), GFP_KERNEL);
239 if (!req)
240 return 0;
241
242 allow_signal(SIGKILL);
243
244 down_write(&host->h_rwsem);
245 lockd_up(net, NULL); /* note: this cannot fail as lockd is already running */
246
247 dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
248
249restart:
250 nsmstate = host->h_nsmstate;
251
252 /* Force a portmap getport - the peer's lockd will
253 * most likely end up on a different port.
254 */
255 host->h_nextrebind = jiffies;
256 nlm_rebind_host(host);
257
258 /* First, reclaim all locks that have been granted. */
259 list_splice_init(&host->h_granted, &host->h_reclaim);
260 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
261 list_del_init(&fl->fl_u.nfs_fl.list);
262
263 /*
264 * sending this thread a SIGKILL will result in any unreclaimed
265 * locks being removed from the h_granted list. This means that
266 * the kernel will not attempt to reclaim them again if a new
267 * reclaimer thread is spawned for this host.
268 */
269 if (signalled())
270 continue;
271 if (nlmclnt_reclaim(host, fl, req) != 0)
272 continue;
273 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
274 if (host->h_nsmstate != nsmstate) {
275 /* Argh! The server rebooted again! */
276 goto restart;
277 }
278 }
279
280 host->h_reclaiming = 0;
281 up_write(&host->h_rwsem);
282 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
283
284 /* Now, wake up all processes that sleep on a blocked lock */
285 spin_lock(&nlm_blocked_lock);
286 list_for_each_entry(block, &nlm_blocked, b_list) {
287 if (block->b_host == host) {
288 block->b_status = nlm_lck_denied_grace_period;
289 wake_up(&block->b_wait);
290 }
291 }
292 spin_unlock(&nlm_blocked_lock);
293
294 /* Release host handle after use */
295 nlmclnt_release_host(host);
296 lockd_down(net);
297 kfree(req);
298 return 0;
299}