USB: drivers/usb/misc/sisusbvga/sisusb.c: kill two unused variables
[linux-2.6/next.git] / fs / lockd / clntlock.c
blobd070b18e539dac18a8e452bff19524e74b1d793e
1 /*
2 * linux/fs/lockd/clntlock.c
4 * Lock handling for the client side NLM implementation
6 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
7 */
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>
18 #define NLMDBG_FACILITY NLMDBG_CLIENT
21 * Local function prototypes
23 static int reclaimer(void *ptr);
26 * The following functions handle blocking and granting from the
27 * client perspective.
31 * This is the representation of a blocked client lock.
33 struct nlm_wait {
34 struct list_head b_list; /* linked list */
35 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 __be32 b_status; /* grant callback status */
42 static LIST_HEAD(nlm_blocked);
45 * Queue up a lock for blocking so that the GRANTED request can see it
47 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
49 struct nlm_wait *block;
51 block = kmalloc(sizeof(*block), GFP_KERNEL);
52 if (block != NULL) {
53 block->b_host = host;
54 block->b_lock = fl;
55 init_waitqueue_head(&block->b_wait);
56 block->b_status = nlm_lck_blocked;
57 list_add(&block->b_list, &nlm_blocked);
59 return block;
62 void nlmclnt_finish_block(struct nlm_wait *block)
64 if (block == NULL)
65 return;
66 list_del(&block->b_list);
67 kfree(block);
71 * Block on a lock
73 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
75 long ret;
77 /* A borken server might ask us to block even if we didn't
78 * request it. Just say no!
80 if (block == NULL)
81 return -EAGAIN;
83 /* Go to sleep waiting for GRANT callback. Some servers seem
84 * to lose callbacks, however, so we're going to poll from
85 * time to time just to make sure.
87 * For now, the retry frequency is pretty high; normally
88 * a 1 minute timeout would do. See the comment before
89 * nlmclnt_lock for an explanation.
91 ret = wait_event_interruptible_timeout(block->b_wait,
92 block->b_status != nlm_lck_blocked,
93 timeout);
94 if (ret < 0)
95 return -ERESTARTSYS;
96 req->a_res.status = block->b_status;
97 return 0;
101 * The server lockd has called us back to tell us the lock was granted
103 __be32 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock)
105 const struct file_lock *fl = &lock->fl;
106 const struct nfs_fh *fh = &lock->fh;
107 struct nlm_wait *block;
108 __be32 res = nlm_lck_denied;
111 * Look up blocked request based on arguments.
112 * Warning: must not use cookie to match it!
114 list_for_each_entry(block, &nlm_blocked, b_list) {
115 struct file_lock *fl_blocked = block->b_lock;
117 if (fl_blocked->fl_start != fl->fl_start)
118 continue;
119 if (fl_blocked->fl_end != fl->fl_end)
120 continue;
122 * Careful! The NLM server will return the 32-bit "pid" that
123 * we put on the wire: in this case the lockowner "pid".
125 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
126 continue;
127 if (!nlm_cmp_addr(&block->b_host->h_addr, addr))
128 continue;
129 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
130 continue;
131 /* Alright, we found a lock. Set the return status
132 * and wake up the caller
134 block->b_status = nlm_granted;
135 wake_up(&block->b_wait);
136 res = nlm_granted;
138 return res;
142 * The following procedures deal with the recovery of locks after a
143 * server crash.
147 * Reclaim all locks on server host. We do this by spawning a separate
148 * reclaimer thread.
150 void
151 nlmclnt_recovery(struct nlm_host *host)
153 if (!host->h_reclaiming++) {
154 nlm_get_host(host);
155 __module_get(THIS_MODULE);
156 if (kernel_thread(reclaimer, host, CLONE_FS | CLONE_FILES) < 0)
157 module_put(THIS_MODULE);
161 static int
162 reclaimer(void *ptr)
164 struct nlm_host *host = (struct nlm_host *) ptr;
165 struct nlm_wait *block;
166 struct file_lock *fl, *next;
167 u32 nsmstate;
169 daemonize("%s-reclaim", host->h_name);
170 allow_signal(SIGKILL);
172 down_write(&host->h_rwsem);
174 /* This one ensures that our parent doesn't terminate while the
175 * reclaim is in progress */
176 lock_kernel();
177 lockd_up(0); /* note: this cannot fail as lockd is already running */
179 dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
181 restart:
182 nsmstate = host->h_nsmstate;
184 /* Force a portmap getport - the peer's lockd will
185 * most likely end up on a different port.
187 host->h_nextrebind = jiffies;
188 nlm_rebind_host(host);
190 /* First, reclaim all locks that have been granted. */
191 list_splice_init(&host->h_granted, &host->h_reclaim);
192 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
193 list_del_init(&fl->fl_u.nfs_fl.list);
195 /* Why are we leaking memory here? --okir */
196 if (signalled())
197 continue;
198 if (nlmclnt_reclaim(host, fl) != 0)
199 continue;
200 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
201 if (host->h_nsmstate != nsmstate) {
202 /* Argh! The server rebooted again! */
203 goto restart;
207 host->h_reclaiming = 0;
208 up_write(&host->h_rwsem);
209 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
211 /* Now, wake up all processes that sleep on a blocked lock */
212 list_for_each_entry(block, &nlm_blocked, b_list) {
213 if (block->b_host == host) {
214 block->b_status = nlm_lck_denied_grace_period;
215 wake_up(&block->b_wait);
219 /* Release host handle after use */
220 nlm_release_host(host);
221 lockd_down();
222 unlock_kernel();
223 module_put_and_exit(0);