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 lockd_down(nlm_init->net); 69 return ERR_PTR(-ENOLCK); 70 } 71 72 return host; 73 } 74 EXPORT_SYMBOL_GPL(nlmclnt_init); 75 76 /** 77 * nlmclnt_done - Release resources allocated by nlmclnt_init() 78 * @host: nlm_host structure reserved by nlmclnt_init() 79 * 80 */ 81 void nlmclnt_done(struct nlm_host *host) 82 { 83 struct net *net = host->net; 84 85 nlmclnt_release_host(host); 86 lockd_down(net); 87 } 88 EXPORT_SYMBOL_GPL(nlmclnt_done); 89 90 /* 91 * Queue up a lock for blocking so that the GRANTED request can see it 92 */ 93 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl) 94 { 95 struct nlm_wait *block; 96 97 block = kmalloc(sizeof(*block), GFP_KERNEL); 98 if (block != NULL) { 99 block->b_host = host; 100 block->b_lock = fl; 101 init_waitqueue_head(&block->b_wait); 102 block->b_status = nlm_lck_blocked; 103 104 spin_lock(&nlm_blocked_lock); 105 list_add(&block->b_list, &nlm_blocked); 106 spin_unlock(&nlm_blocked_lock); 107 } 108 return block; 109 } 110 111 void nlmclnt_finish_block(struct nlm_wait *block) 112 { 113 if (block == NULL) 114 return; 115 spin_lock(&nlm_blocked_lock); 116 list_del(&block->b_list); 117 spin_unlock(&nlm_blocked_lock); 118 kfree(block); 119 } 120 121 /* 122 * Block on a lock 123 */ 124 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout) 125 { 126 long ret; 127 128 /* A borken server might ask us to block even if we didn't 129 * request it. Just say no! 130 */ 131 if (block == NULL) 132 return -EAGAIN; 133 134 /* Go to sleep waiting for GRANT callback. Some servers seem 135 * to lose callbacks, however, so we're going to poll from 136 * time to time just to make sure. 137 * 138 * For now, the retry frequency is pretty high; normally 139 * a 1 minute timeout would do. See the comment before 140 * nlmclnt_lock for an explanation. 141 */ 142 ret = wait_event_interruptible_timeout(block->b_wait, 143 block->b_status != nlm_lck_blocked, 144 timeout); 145 if (ret < 0) 146 return -ERESTARTSYS; 147 req->a_res.status = block->b_status; 148 return 0; 149 } 150 151 /* 152 * The server lockd has called us back to tell us the lock was granted 153 */ 154 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock) 155 { 156 const struct file_lock *fl = &lock->fl; 157 const struct nfs_fh *fh = &lock->fh; 158 struct nlm_wait *block; 159 __be32 res = nlm_lck_denied; 160 161 /* 162 * Look up blocked request based on arguments. 163 * Warning: must not use cookie to match it! 164 */ 165 spin_lock(&nlm_blocked_lock); 166 list_for_each_entry(block, &nlm_blocked, b_list) { 167 struct file_lock *fl_blocked = block->b_lock; 168 169 if (fl_blocked->fl_start != fl->fl_start) 170 continue; 171 if (fl_blocked->fl_end != fl->fl_end) 172 continue; 173 /* 174 * Careful! The NLM server will return the 32-bit "pid" that 175 * we put on the wire: in this case the lockowner "pid". 176 */ 177 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) 178 continue; 179 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr)) 180 continue; 181 if (nfs_compare_fh(NFS_FH(file_inode(fl_blocked->fl_file)) ,fh) != 0) 182 continue; 183 /* Alright, we found a lock. Set the return status 184 * and wake up the caller 185 */ 186 block->b_status = nlm_granted; 187 wake_up(&block->b_wait); 188 res = nlm_granted; 189 } 190 spin_unlock(&nlm_blocked_lock); 191 return res; 192 } 193 194 /* 195 * The following procedures deal with the recovery of locks after a 196 * server crash. 197 */ 198 199 /* 200 * Reclaim all locks on server host. We do this by spawning a separate 201 * reclaimer thread. 202 */ 203 void 204 nlmclnt_recovery(struct nlm_host *host) 205 { 206 struct task_struct *task; 207 208 if (!host->h_reclaiming++) { 209 nlm_get_host(host); 210 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name); 211 if (IS_ERR(task)) 212 printk(KERN_ERR "lockd: unable to spawn reclaimer " 213 "thread. Locks for %s won't be reclaimed! " 214 "(%ld)\n", host->h_name, PTR_ERR(task)); 215 } 216 } 217 218 static int 219 reclaimer(void *ptr) 220 { 221 struct nlm_host *host = (struct nlm_host *) ptr; 222 struct nlm_wait *block; 223 struct nlm_rqst *req; 224 struct file_lock *fl, *next; 225 u32 nsmstate; 226 struct net *net = host->net; 227 228 req = kmalloc(sizeof(*req), GFP_KERNEL); 229 if (!req) { 230 printk(KERN_ERR "lockd: reclaimer unable to alloc memory." 231 " Locks for %s won't be reclaimed!\n", 232 host->h_name); 233 return 0; 234 } 235 236 allow_signal(SIGKILL); 237 238 down_write(&host->h_rwsem); 239 lockd_up(net); /* note: this cannot fail as lockd is already running */ 240 241 dprintk("lockd: reclaiming locks for host %s\n", host->h_name); 242 243 restart: 244 nsmstate = host->h_nsmstate; 245 246 /* Force a portmap getport - the peer's lockd will 247 * most likely end up on a different port. 248 */ 249 host->h_nextrebind = jiffies; 250 nlm_rebind_host(host); 251 252 /* First, reclaim all locks that have been granted. */ 253 list_splice_init(&host->h_granted, &host->h_reclaim); 254 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { 255 list_del_init(&fl->fl_u.nfs_fl.list); 256 257 /* 258 * sending this thread a SIGKILL will result in any unreclaimed 259 * locks being removed from the h_granted list. This means that 260 * the kernel will not attempt to reclaim them again if a new 261 * reclaimer thread is spawned for this host. 262 */ 263 if (signalled()) 264 continue; 265 if (nlmclnt_reclaim(host, fl, req) != 0) 266 continue; 267 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); 268 if (host->h_nsmstate != nsmstate) { 269 /* Argh! The server rebooted again! */ 270 goto restart; 271 } 272 } 273 274 host->h_reclaiming = 0; 275 up_write(&host->h_rwsem); 276 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name); 277 278 /* Now, wake up all processes that sleep on a blocked lock */ 279 spin_lock(&nlm_blocked_lock); 280 list_for_each_entry(block, &nlm_blocked, b_list) { 281 if (block->b_host == host) { 282 block->b_status = nlm_lck_denied_grace_period; 283 wake_up(&block->b_wait); 284 } 285 } 286 spin_unlock(&nlm_blocked_lock); 287 288 /* Release host handle after use */ 289 nlmclnt_release_host(host); 290 lockd_down(net); 291 kfree(req); 292 return 0; 293 } 294