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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
18#define NLMDBG_FACILITY NLMDBG_CLIENT
19
20/*
21 * Local function prototypes
22 */
23static int reclaimer(void *ptr);
24
25/*
26 * The following functions handle blocking and granting from the
27 * client perspective.
28 */
29
30/*
31 * This is the representation of a blocked client lock.
32 */
33struct nlm_wait {
Trond Myklebust4f15e2b2005-06-22 17:16:31 +000034 struct list_head b_list; /* linked list */
Linus Torvalds1da177e2005-04-16 15:20:36 -070035 wait_queue_head_t b_wait; /* where to wait on */
36 struct nlm_host * b_host;
37 struct file_lock * b_lock; /* local file lock */
38 unsigned short b_reclaim; /* got to reclaim lock */
39 u32 b_status; /* grant callback status */
40};
41
Trond Myklebust4f15e2b2005-06-22 17:16:31 +000042static LIST_HEAD(nlm_blocked);
Linus Torvalds1da177e2005-04-16 15:20:36 -070043
44/*
Trond Myklebustecdbf762005-06-22 17:16:31 +000045 * Queue up a lock for blocking so that the GRANTED request can see it
46 */
47int nlmclnt_prepare_block(struct nlm_rqst *req, struct nlm_host *host, struct file_lock *fl)
48{
49 struct nlm_wait *block;
50
51 BUG_ON(req->a_block != NULL);
52 block = kmalloc(sizeof(*block), GFP_KERNEL);
53 if (block == NULL)
54 return -ENOMEM;
55 block->b_host = host;
56 block->b_lock = fl;
57 init_waitqueue_head(&block->b_wait);
58 block->b_status = NLM_LCK_BLOCKED;
59
60 list_add(&block->b_list, &nlm_blocked);
61 req->a_block = block;
62
63 return 0;
64}
65
66void nlmclnt_finish_block(struct nlm_rqst *req)
67{
68 struct nlm_wait *block = req->a_block;
69
70 if (block == NULL)
71 return;
72 req->a_block = NULL;
73 list_del(&block->b_list);
74 kfree(block);
75}
76
77/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 * Block on a lock
79 */
Trond Myklebustecdbf762005-06-22 17:16:31 +000080long nlmclnt_block(struct nlm_rqst *req, long timeout)
Linus Torvalds1da177e2005-04-16 15:20:36 -070081{
Trond Myklebustecdbf762005-06-22 17:16:31 +000082 struct nlm_wait *block = req->a_block;
83 long ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -070084
Trond Myklebustecdbf762005-06-22 17:16:31 +000085 /* A borken server might ask us to block even if we didn't
86 * request it. Just say no!
87 */
88 if (!req->a_args.block)
89 return -EAGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
91 /* Go to sleep waiting for GRANT callback. Some servers seem
92 * to lose callbacks, however, so we're going to poll from
93 * time to time just to make sure.
94 *
95 * For now, the retry frequency is pretty high; normally
96 * a 1 minute timeout would do. See the comment before
97 * nlmclnt_lock for an explanation.
98 */
Trond Myklebustecdbf762005-06-22 17:16:31 +000099 ret = wait_event_interruptible_timeout(block->b_wait,
100 block->b_status != NLM_LCK_BLOCKED,
101 timeout);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102
Trond Myklebustecdbf762005-06-22 17:16:31 +0000103 if (block->b_status != NLM_LCK_BLOCKED) {
104 req->a_res.status = block->b_status;
105 block->b_status = NLM_LCK_BLOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700106 }
107
Trond Myklebustecdbf762005-06-22 17:16:31 +0000108 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109}
110
111/*
112 * The server lockd has called us back to tell us the lock was granted
113 */
114u32
115nlmclnt_grant(struct nlm_lock *lock)
116{
117 struct nlm_wait *block;
Trond Myklebustecdbf762005-06-22 17:16:31 +0000118 u32 res = nlm_lck_denied;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119
120 /*
121 * Look up blocked request based on arguments.
122 * Warning: must not use cookie to match it!
123 */
Trond Myklebust4f15e2b2005-06-22 17:16:31 +0000124 list_for_each_entry(block, &nlm_blocked, b_list) {
Trond Myklebustecdbf762005-06-22 17:16:31 +0000125 if (nlm_compare_locks(block->b_lock, &lock->fl)) {
126 /* Alright, we found a lock. Set the return status
127 * and wake up the caller
128 */
129 block->b_status = NLM_LCK_GRANTED;
130 wake_up(&block->b_wait);
131 res = nlm_granted;
132 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 }
Trond Myklebustecdbf762005-06-22 17:16:31 +0000134 return res;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135}
136
137/*
138 * The following procedures deal with the recovery of locks after a
139 * server crash.
140 */
141
142/*
143 * Mark the locks for reclaiming.
144 * FIXME: In 2.5 we don't want to iterate through any global file_lock_list.
145 * Maintain NLM lock reclaiming lists in the nlm_host instead.
146 */
147static
148void nlmclnt_mark_reclaim(struct nlm_host *host)
149{
150 struct file_lock *fl;
151 struct inode *inode;
152 struct list_head *tmp;
153
154 list_for_each(tmp, &file_lock_list) {
155 fl = list_entry(tmp, struct file_lock, fl_link);
156
157 inode = fl->fl_file->f_dentry->d_inode;
158 if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
159 continue;
160 if (fl->fl_u.nfs_fl.owner->host != host)
161 continue;
162 if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED))
163 continue;
164 fl->fl_u.nfs_fl.flags |= NFS_LCK_RECLAIM;
165 }
166}
167
168/*
169 * Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number,
170 * that we mark locks for reclaiming, and that we bump the pseudo NSM state.
171 */
172static inline
173void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate)
174{
175 host->h_monitored = 0;
176 host->h_nsmstate = newstate;
177 host->h_state++;
178 host->h_nextrebind = 0;
179 nlm_rebind_host(host);
180 nlmclnt_mark_reclaim(host);
181 dprintk("NLM: reclaiming locks for host %s", host->h_name);
182}
183
184/*
185 * Reclaim all locks on server host. We do this by spawning a separate
186 * reclaimer thread.
187 */
188void
189nlmclnt_recovery(struct nlm_host *host, u32 newstate)
190{
191 if (host->h_reclaiming++) {
192 if (host->h_nsmstate == newstate)
193 return;
194 nlmclnt_prepare_reclaim(host, newstate);
195 } else {
196 nlmclnt_prepare_reclaim(host, newstate);
197 nlm_get_host(host);
198 __module_get(THIS_MODULE);
199 if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
200 module_put(THIS_MODULE);
201 }
202}
203
204static int
205reclaimer(void *ptr)
206{
207 struct nlm_host *host = (struct nlm_host *) ptr;
208 struct nlm_wait *block;
209 struct list_head *tmp;
210 struct file_lock *fl;
211 struct inode *inode;
212
213 daemonize("%s-reclaim", host->h_name);
214 allow_signal(SIGKILL);
215
216 /* This one ensures that our parent doesn't terminate while the
217 * reclaim is in progress */
218 lock_kernel();
219 lockd_up();
220
221 /* First, reclaim all locks that have been marked. */
222restart:
223 list_for_each(tmp, &file_lock_list) {
224 fl = list_entry(tmp, struct file_lock, fl_link);
225
226 inode = fl->fl_file->f_dentry->d_inode;
227 if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
228 continue;
229 if (fl->fl_u.nfs_fl.owner->host != host)
230 continue;
231 if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM))
232 continue;
233
234 fl->fl_u.nfs_fl.flags &= ~NFS_LCK_RECLAIM;
235 nlmclnt_reclaim(host, fl);
236 if (signalled())
237 break;
238 goto restart;
239 }
240
241 host->h_reclaiming = 0;
242
243 /* Now, wake up all processes that sleep on a blocked lock */
Trond Myklebust4f15e2b2005-06-22 17:16:31 +0000244 list_for_each_entry(block, &nlm_blocked, b_list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 if (block->b_host == host) {
246 block->b_status = NLM_LCK_DENIED_GRACE_PERIOD;
247 wake_up(&block->b_wait);
248 }
249 }
250
251 /* Release host handle after use */
252 nlm_release_host(host);
253 lockd_down();
254 unlock_kernel();
255 module_put_and_exit(0);
256}