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