Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target...
[linux-btrfs-devel.git] / fs / lockd / clntlock.c
blob8d4ea8351e3d4e093263104764d0f959aa35c05b
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/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>
19 #define NLMDBG_FACILITY NLMDBG_CLIENT
22 * Local function prototypes
24 static int reclaimer(void *ptr);
27 * The following functions handle blocking and granting from the
28 * client perspective.
32 * This is the representation of a blocked client lock.
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 */
43 static LIST_HEAD(nlm_blocked);
44 static DEFINE_SPINLOCK(nlm_blocked_lock);
46 /**
47 * nlmclnt_init - Set up per-NFS mount point lockd data structures
48 * @nlm_init: pointer to arguments structure
50 * Returns pointer to an appropriate nlm_host struct,
51 * or an ERR_PTR value.
53 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
55 struct nlm_host *host;
56 u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
57 int status;
59 status = lockd_up();
60 if (status < 0)
61 return ERR_PTR(status);
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 if (host == NULL) {
67 lockd_down();
68 return ERR_PTR(-ENOLCK);
71 return host;
73 EXPORT_SYMBOL_GPL(nlmclnt_init);
75 /**
76 * nlmclnt_done - Release resources allocated by nlmclnt_init()
77 * @host: nlm_host structure reserved by nlmclnt_init()
80 void nlmclnt_done(struct nlm_host *host)
82 nlmclnt_release_host(host);
83 lockd_down();
85 EXPORT_SYMBOL_GPL(nlmclnt_done);
88 * Queue up a lock for blocking so that the GRANTED request can see it
90 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
92 struct nlm_wait *block;
94 block = kmalloc(sizeof(*block), GFP_KERNEL);
95 if (block != NULL) {
96 block->b_host = host;
97 block->b_lock = fl;
98 init_waitqueue_head(&block->b_wait);
99 block->b_status = nlm_lck_blocked;
101 spin_lock(&nlm_blocked_lock);
102 list_add(&block->b_list, &nlm_blocked);
103 spin_unlock(&nlm_blocked_lock);
105 return block;
108 void nlmclnt_finish_block(struct nlm_wait *block)
110 if (block == NULL)
111 return;
112 spin_lock(&nlm_blocked_lock);
113 list_del(&block->b_list);
114 spin_unlock(&nlm_blocked_lock);
115 kfree(block);
119 * Block on a lock
121 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
123 long ret;
125 /* A borken server might ask us to block even if we didn't
126 * request it. Just say no!
128 if (block == NULL)
129 return -EAGAIN;
131 /* Go to sleep waiting for GRANT callback. Some servers seem
132 * to lose callbacks, however, so we're going to poll from
133 * time to time just to make sure.
135 * For now, the retry frequency is pretty high; normally
136 * a 1 minute timeout would do. See the comment before
137 * nlmclnt_lock for an explanation.
139 ret = wait_event_interruptible_timeout(block->b_wait,
140 block->b_status != nlm_lck_blocked,
141 timeout);
142 if (ret < 0)
143 return -ERESTARTSYS;
144 req->a_res.status = block->b_status;
145 return 0;
149 * The server lockd has called us back to tell us the lock was granted
151 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
153 const struct file_lock *fl = &lock->fl;
154 const struct nfs_fh *fh = &lock->fh;
155 struct nlm_wait *block;
156 __be32 res = nlm_lck_denied;
159 * Look up blocked request based on arguments.
160 * Warning: must not use cookie to match it!
162 spin_lock(&nlm_blocked_lock);
163 list_for_each_entry(block, &nlm_blocked, b_list) {
164 struct file_lock *fl_blocked = block->b_lock;
166 if (fl_blocked->fl_start != fl->fl_start)
167 continue;
168 if (fl_blocked->fl_end != fl->fl_end)
169 continue;
171 * Careful! The NLM server will return the 32-bit "pid" that
172 * we put on the wire: in this case the lockowner "pid".
174 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
175 continue;
176 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
177 continue;
178 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
179 continue;
180 /* Alright, we found a lock. Set the return status
181 * and wake up the caller
183 block->b_status = nlm_granted;
184 wake_up(&block->b_wait);
185 res = nlm_granted;
187 spin_unlock(&nlm_blocked_lock);
188 return res;
192 * The following procedures deal with the recovery of locks after a
193 * server crash.
197 * Reclaim all locks on server host. We do this by spawning a separate
198 * reclaimer thread.
200 void
201 nlmclnt_recovery(struct nlm_host *host)
203 struct task_struct *task;
205 if (!host->h_reclaiming++) {
206 nlm_get_host(host);
207 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
208 if (IS_ERR(task))
209 printk(KERN_ERR "lockd: unable to spawn reclaimer "
210 "thread. Locks for %s won't be reclaimed! "
211 "(%ld)\n", host->h_name, PTR_ERR(task));
215 static int
216 reclaimer(void *ptr)
218 struct nlm_host *host = (struct nlm_host *) ptr;
219 struct nlm_wait *block;
220 struct file_lock *fl, *next;
221 u32 nsmstate;
223 allow_signal(SIGKILL);
225 down_write(&host->h_rwsem);
226 lockd_up(); /* note: this cannot fail as lockd is already running */
228 dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
230 restart:
231 nsmstate = host->h_nsmstate;
233 /* Force a portmap getport - the peer's lockd will
234 * most likely end up on a different port.
236 host->h_nextrebind = jiffies;
237 nlm_rebind_host(host);
239 /* First, reclaim all locks that have been granted. */
240 list_splice_init(&host->h_granted, &host->h_reclaim);
241 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
242 list_del_init(&fl->fl_u.nfs_fl.list);
245 * sending this thread a SIGKILL will result in any unreclaimed
246 * locks being removed from the h_granted list. This means that
247 * the kernel will not attempt to reclaim them again if a new
248 * reclaimer thread is spawned for this host.
250 if (signalled())
251 continue;
252 if (nlmclnt_reclaim(host, fl) != 0)
253 continue;
254 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
255 if (host->h_nsmstate != nsmstate) {
256 /* Argh! The server rebooted again! */
257 goto restart;
261 host->h_reclaiming = 0;
262 up_write(&host->h_rwsem);
263 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
265 /* Now, wake up all processes that sleep on a blocked lock */
266 spin_lock(&nlm_blocked_lock);
267 list_for_each_entry(block, &nlm_blocked, b_list) {
268 if (block->b_host == host) {
269 block->b_status = nlm_lck_denied_grace_period;
270 wake_up(&block->b_wait);
273 spin_unlock(&nlm_blocked_lock);
275 /* Release host handle after use */
276 nlmclnt_release_host(host);
277 lockd_down();
278 return 0;