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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         return host;
 73 out_nobind:
 74         nlmclnt_release_host(host);
 75 out_nohost:
 76         lockd_down(nlm_init->net);
 77         return ERR_PTR(-ENOLCK);
 78 }
 79 EXPORT_SYMBOL_GPL(nlmclnt_init);
 80 
 81 /**
 82  * nlmclnt_done - Release resources allocated by nlmclnt_init()
 83  * @host: nlm_host structure reserved by nlmclnt_init()
 84  *
 85  */
 86 void nlmclnt_done(struct nlm_host *host)
 87 {
 88         struct net *net = host->net;
 89 
 90         nlmclnt_release_host(host);
 91         lockd_down(net);
 92 }
 93 EXPORT_SYMBOL_GPL(nlmclnt_done);
 94 
 95 /*
 96  * Queue up a lock for blocking so that the GRANTED request can see it
 97  */
 98 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
 99 {
100         struct nlm_wait *block;
101 
102         block = kmalloc(sizeof(*block), GFP_KERNEL);
103         if (block != NULL) {
104                 block->b_host = host;
105                 block->b_lock = fl;
106                 init_waitqueue_head(&block->b_wait);
107                 block->b_status = nlm_lck_blocked;
108 
109                 spin_lock(&nlm_blocked_lock);
110                 list_add(&block->b_list, &nlm_blocked);
111                 spin_unlock(&nlm_blocked_lock);
112         }
113         return block;
114 }
115 
116 void nlmclnt_finish_block(struct nlm_wait *block)
117 {
118         if (block == NULL)
119                 return;
120         spin_lock(&nlm_blocked_lock);
121         list_del(&block->b_list);
122         spin_unlock(&nlm_blocked_lock);
123         kfree(block);
124 }
125 
126 /*
127  * Block on a lock
128  */
129 int nlmclnt_block(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         req->a_res.status = block->b_status;
156         return 0;
157 }
158 
159 /*
160  * The server lockd has called us back to tell us the lock was granted
161  */
162 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
163 {
164         const struct file_lock *fl = &lock->fl;
165         const struct nfs_fh *fh = &lock->fh;
166         struct nlm_wait *block;
167         __be32 res = nlm_lck_denied;
168 
169         /*
170          * Look up blocked request based on arguments. 
171          * Warning: must not use cookie to match it!
172          */
173         spin_lock(&nlm_blocked_lock);
174         list_for_each_entry(block, &nlm_blocked, b_list) {
175                 struct file_lock *fl_blocked = block->b_lock;
176 
177                 if (fl_blocked->fl_start != fl->fl_start)
178                         continue;
179                 if (fl_blocked->fl_end != fl->fl_end)
180                         continue;
181                 /*
182                  * Careful! The NLM server will return the 32-bit "pid" that
183                  * we put on the wire: in this case the lockowner "pid".
184                  */
185                 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
186                         continue;
187                 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
188                         continue;
189                 if (nfs_compare_fh(NFS_FH(file_inode(fl_blocked->fl_file)) ,fh) != 0)
190                         continue;
191                 /* Alright, we found a lock. Set the return status
192                  * and wake up the caller
193                  */
194                 block->b_status = nlm_granted;
195                 wake_up(&block->b_wait);
196                 res = nlm_granted;
197         }
198         spin_unlock(&nlm_blocked_lock);
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  */
211 void
212 nlmclnt_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(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 
226 static int
227 reclaimer(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                 printk(KERN_ERR "lockd: reclaimer unable to alloc memory."
239                                 " Locks for %s won't be reclaimed!\n",
240                                 host->h_name);
241                 return 0;
242         }
243 
244         allow_signal(SIGKILL);
245 
246         down_write(&host->h_rwsem);
247         lockd_up(net);  /* note: this cannot fail as lockd is already running */
248 
249         dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
250 
251 restart:
252         nsmstate = host->h_nsmstate;
253 
254         /* Force a portmap getport - the peer's lockd will
255          * most likely end up on a different port.
256          */
257         host->h_nextrebind = jiffies;
258         nlm_rebind_host(host);
259 
260         /* First, reclaim all locks that have been granted. */
261         list_splice_init(&host->h_granted, &host->h_reclaim);
262         list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
263                 list_del_init(&fl->fl_u.nfs_fl.list);
264 
265                 /*
266                  * sending this thread a SIGKILL will result in any unreclaimed
267                  * locks being removed from the h_granted list. This means that
268                  * the kernel will not attempt to reclaim them again if a new
269                  * reclaimer thread is spawned for this host.
270                  */
271                 if (signalled())
272                         continue;
273                 if (nlmclnt_reclaim(host, fl, req) != 0)
274                         continue;
275                 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
276                 if (host->h_nsmstate != nsmstate) {
277                         /* Argh! The server rebooted again! */
278                         goto restart;
279                 }
280         }
281 
282         host->h_reclaiming = 0;
283         up_write(&host->h_rwsem);
284         dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
285 
286         /* Now, wake up all processes that sleep on a blocked lock */
287         spin_lock(&nlm_blocked_lock);
288         list_for_each_entry(block, &nlm_blocked, b_list) {
289                 if (block->b_host == host) {
290                         block->b_status = nlm_lck_denied_grace_period;
291                         wake_up(&block->b_wait);
292                 }
293         }
294         spin_unlock(&nlm_blocked_lock);
295 
296         /* Release host handle after use */
297         nlmclnt_release_host(host);
298         lockd_down(net);
299         kfree(req);
300         return 0;
301 }
302 

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