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/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 #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 45 /** 46 * nlmclnt_init - Set up per-NFS mount point lockd data structures 47 * @nlm_init: pointer to arguments structure 48 * 49 * Returns pointer to an appropriate nlm_host struct, 50 * or an ERR_PTR value. 51 */ 52 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init) 53 { 54 struct nlm_host *host; 55 u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4; 56 int status; 57 58 status = lockd_up(); 59 if (status < 0) 60 return ERR_PTR(status); 61 62 host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen, 63 nlm_init->protocol, nlm_version, 64 nlm_init->hostname, nlm_init->noresvport); 65 if (host == NULL) { 66 lockd_down(); 67 return ERR_PTR(-ENOLCK); 68 } 69 70 return host; 71 } 72 EXPORT_SYMBOL_GPL(nlmclnt_init); 73 74 /** 75 * nlmclnt_done - Release resources allocated by nlmclnt_init() 76 * @host: nlm_host structure reserved by nlmclnt_init() 77 * 78 */ 79 void nlmclnt_done(struct nlm_host *host) 80 { 81 nlm_release_host(host); 82 lockd_down(); 83 } 84 EXPORT_SYMBOL_GPL(nlmclnt_done); 85 86 /* 87 * Queue up a lock for blocking so that the GRANTED request can see it 88 */ 89 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl) 90 { 91 struct nlm_wait *block; 92 93 block = kmalloc(sizeof(*block), GFP_KERNEL); 94 if (block != NULL) { 95 block->b_host = host; 96 block->b_lock = fl; 97 init_waitqueue_head(&block->b_wait); 98 block->b_status = nlm_lck_blocked; 99 list_add(&block->b_list, &nlm_blocked); 100 } 101 return block; 102 } 103 104 void nlmclnt_finish_block(struct nlm_wait *block) 105 { 106 if (block == NULL) 107 return; 108 list_del(&block->b_list); 109 kfree(block); 110 } 111 112 /* 113 * Block on a lock 114 */ 115 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout) 116 { 117 long ret; 118 119 /* A borken server might ask us to block even if we didn't 120 * request it. Just say no! 121 */ 122 if (block == NULL) 123 return -EAGAIN; 124 125 /* Go to sleep waiting for GRANT callback. Some servers seem 126 * to lose callbacks, however, so we're going to poll from 127 * time to time just to make sure. 128 * 129 * For now, the retry frequency is pretty high; normally 130 * a 1 minute timeout would do. See the comment before 131 * nlmclnt_lock for an explanation. 132 */ 133 ret = wait_event_interruptible_timeout(block->b_wait, 134 block->b_status != nlm_lck_blocked, 135 timeout); 136 if (ret < 0) 137 return -ERESTARTSYS; 138 req->a_res.status = block->b_status; 139 return 0; 140 } 141 142 /* 143 * The server lockd has called us back to tell us the lock was granted 144 */ 145 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock) 146 { 147 const struct file_lock *fl = &lock->fl; 148 const struct nfs_fh *fh = &lock->fh; 149 struct nlm_wait *block; 150 __be32 res = nlm_lck_denied; 151 152 /* 153 * Look up blocked request based on arguments. 154 * Warning: must not use cookie to match it! 155 */ 156 list_for_each_entry(block, &nlm_blocked, b_list) { 157 struct file_lock *fl_blocked = block->b_lock; 158 159 if (fl_blocked->fl_start != fl->fl_start) 160 continue; 161 if (fl_blocked->fl_end != fl->fl_end) 162 continue; 163 /* 164 * Careful! The NLM server will return the 32-bit "pid" that 165 * we put on the wire: in this case the lockowner "pid". 166 */ 167 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) 168 continue; 169 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr)) 170 continue; 171 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0) 172 continue; 173 /* Alright, we found a lock. Set the return status 174 * and wake up the caller 175 */ 176 block->b_status = nlm_granted; 177 wake_up(&block->b_wait); 178 res = nlm_granted; 179 } 180 return res; 181 } 182 183 /* 184 * The following procedures deal with the recovery of locks after a 185 * server crash. 186 */ 187 188 /* 189 * Reclaim all locks on server host. We do this by spawning a separate 190 * reclaimer thread. 191 */ 192 void 193 nlmclnt_recovery(struct nlm_host *host) 194 { 195 struct task_struct *task; 196 197 if (!host->h_reclaiming++) { 198 nlm_get_host(host); 199 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name); 200 if (IS_ERR(task)) 201 printk(KERN_ERR "lockd: unable to spawn reclaimer " 202 "thread. Locks for %s won't be reclaimed! " 203 "(%ld)\n", host->h_name, PTR_ERR(task)); 204 } 205 } 206 207 static int 208 reclaimer(void *ptr) 209 { 210 struct nlm_host *host = (struct nlm_host *) ptr; 211 struct nlm_wait *block; 212 struct file_lock *fl, *next; 213 u32 nsmstate; 214 215 allow_signal(SIGKILL); 216 217 down_write(&host->h_rwsem); 218 219 /* This one ensures that our parent doesn't terminate while the 220 * reclaim is in progress */ 221 lock_kernel(); 222 lockd_up(); /* note: this cannot fail as lockd is already running */ 223 224 dprintk("lockd: reclaiming locks for host %s\n", host->h_name); 225 226 restart: 227 nsmstate = host->h_nsmstate; 228 229 /* Force a portmap getport - the peer's lockd will 230 * most likely end up on a different port. 231 */ 232 host->h_nextrebind = jiffies; 233 nlm_rebind_host(host); 234 235 /* First, reclaim all locks that have been granted. */ 236 list_splice_init(&host->h_granted, &host->h_reclaim); 237 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { 238 list_del_init(&fl->fl_u.nfs_fl.list); 239 240 /* 241 * sending this thread a SIGKILL will result in any unreclaimed 242 * locks being removed from the h_granted list. This means that 243 * the kernel will not attempt to reclaim them again if a new 244 * reclaimer thread is spawned for this host. 245 */ 246 if (signalled()) 247 continue; 248 if (nlmclnt_reclaim(host, fl) != 0) 249 continue; 250 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); 251 if (host->h_nsmstate != nsmstate) { 252 /* Argh! The server rebooted again! */ 253 goto restart; 254 } 255 } 256 257 host->h_reclaiming = 0; 258 up_write(&host->h_rwsem); 259 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name); 260 261 /* Now, wake up all processes that sleep on a blocked lock */ 262 list_for_each_entry(block, &nlm_blocked, b_list) { 263 if (block->b_host == host) { 264 block->b_status = nlm_lck_denied_grace_period; 265 wake_up(&block->b_wait); 266 } 267 } 268 269 /* Release host handle after use */ 270 nlm_release_host(host); 271 lockd_down(); 272 unlock_kernel(); 273 return 0; 274 } 275