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