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Linux/fs/lockd/clntlock.c

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

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