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