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/smp_lock.h> 18 #include <linux/kthread.h> 19 20 #define NLMDBG_FACILITY NLMDBG_CLIENT 21 22 /* 23 * Local function prototypes 24 */ 25 static int reclaimer(void *ptr); 26 27 /* 28 * The following functions handle blocking and granting from the 29 * client perspective. 30 */ 31 32 /* 33 * This is the representation of a blocked client lock. 34 */ 35 struct nlm_wait { 36 struct list_head b_list; /* linked list */ 37 wait_queue_head_t b_wait; /* where to wait on */ 38 struct nlm_host * b_host; 39 struct file_lock * b_lock; /* local file lock */ 40 unsigned short b_reclaim; /* got to reclaim lock */ 41 __be32 b_status; /* grant callback status */ 42 }; 43 44 static LIST_HEAD(nlm_blocked); 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 if (host == NULL) { 67 lockd_down(); 68 return ERR_PTR(-ENOLCK); 69 } 70 71 return host; 72 } 73 EXPORT_SYMBOL_GPL(nlmclnt_init); 74 75 /** 76 * nlmclnt_done - Release resources allocated by nlmclnt_init() 77 * @host: nlm_host structure reserved by nlmclnt_init() 78 * 79 */ 80 void nlmclnt_done(struct nlm_host *host) 81 { 82 nlm_release_host(host); 83 lockd_down(); 84 } 85 EXPORT_SYMBOL_GPL(nlmclnt_done); 86 87 /* 88 * Queue up a lock for blocking so that the GRANTED request can see it 89 */ 90 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl) 91 { 92 struct nlm_wait *block; 93 94 block = kmalloc(sizeof(*block), GFP_KERNEL); 95 if (block != NULL) { 96 block->b_host = host; 97 block->b_lock = fl; 98 init_waitqueue_head(&block->b_wait); 99 block->b_status = nlm_lck_blocked; 100 list_add(&block->b_list, &nlm_blocked); 101 } 102 return block; 103 } 104 105 void nlmclnt_finish_block(struct nlm_wait *block) 106 { 107 if (block == NULL) 108 return; 109 list_del(&block->b_list); 110 kfree(block); 111 } 112 113 /* 114 * Block on a lock 115 */ 116 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout) 117 { 118 long ret; 119 120 /* A borken server might ask us to block even if we didn't 121 * request it. Just say no! 122 */ 123 if (block == NULL) 124 return -EAGAIN; 125 126 /* Go to sleep waiting for GRANT callback. Some servers seem 127 * to lose callbacks, however, so we're going to poll from 128 * time to time just to make sure. 129 * 130 * For now, the retry frequency is pretty high; normally 131 * a 1 minute timeout would do. See the comment before 132 * nlmclnt_lock for an explanation. 133 */ 134 ret = wait_event_interruptible_timeout(block->b_wait, 135 block->b_status != nlm_lck_blocked, 136 timeout); 137 if (ret < 0) 138 return -ERESTARTSYS; 139 req->a_res.status = block->b_status; 140 return 0; 141 } 142 143 /* 144 * The server lockd has called us back to tell us the lock was granted 145 */ 146 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock) 147 { 148 const struct file_lock *fl = &lock->fl; 149 const struct nfs_fh *fh = &lock->fh; 150 struct nlm_wait *block; 151 __be32 res = nlm_lck_denied; 152 153 /* 154 * Look up blocked request based on arguments. 155 * Warning: must not use cookie to match it! 156 */ 157 list_for_each_entry(block, &nlm_blocked, b_list) { 158 struct file_lock *fl_blocked = block->b_lock; 159 160 if (fl_blocked->fl_start != fl->fl_start) 161 continue; 162 if (fl_blocked->fl_end != fl->fl_end) 163 continue; 164 /* 165 * Careful! The NLM server will return the 32-bit "pid" that 166 * we put on the wire: in this case the lockowner "pid". 167 */ 168 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) 169 continue; 170 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr)) 171 continue; 172 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0) 173 continue; 174 /* Alright, we found a lock. Set the return status 175 * and wake up the caller 176 */ 177 block->b_status = nlm_granted; 178 wake_up(&block->b_wait); 179 res = nlm_granted; 180 } 181 return res; 182 } 183 184 /* 185 * The following procedures deal with the recovery of locks after a 186 * server crash. 187 */ 188 189 /* 190 * Reclaim all locks on server host. We do this by spawning a separate 191 * reclaimer thread. 192 */ 193 void 194 nlmclnt_recovery(struct nlm_host *host) 195 { 196 struct task_struct *task; 197 198 if (!host->h_reclaiming++) { 199 nlm_get_host(host); 200 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name); 201 if (IS_ERR(task)) 202 printk(KERN_ERR "lockd: unable to spawn reclaimer " 203 "thread. Locks for %s won't be reclaimed! " 204 "(%ld)\n", host->h_name, PTR_ERR(task)); 205 } 206 } 207 208 static int 209 reclaimer(void *ptr) 210 { 211 struct nlm_host *host = (struct nlm_host *) ptr; 212 struct nlm_wait *block; 213 struct file_lock *fl, *next; 214 u32 nsmstate; 215 216 allow_signal(SIGKILL); 217 218 down_write(&host->h_rwsem); 219 220 /* This one ensures that our parent doesn't terminate while the 221 * reclaim is in progress */ 222 lock_kernel(); 223 lockd_up(); /* note: this cannot fail as lockd is already running */ 224 225 dprintk("lockd: reclaiming locks for host %s\n", host->h_name); 226 227 restart: 228 nsmstate = host->h_nsmstate; 229 230 /* Force a portmap getport - the peer's lockd will 231 * most likely end up on a different port. 232 */ 233 host->h_nextrebind = jiffies; 234 nlm_rebind_host(host); 235 236 /* First, reclaim all locks that have been granted. */ 237 list_splice_init(&host->h_granted, &host->h_reclaim); 238 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { 239 list_del_init(&fl->fl_u.nfs_fl.list); 240 241 /* 242 * sending this thread a SIGKILL will result in any unreclaimed 243 * locks being removed from the h_granted list. This means that 244 * the kernel will not attempt to reclaim them again if a new 245 * reclaimer thread is spawned for this host. 246 */ 247 if (signalled()) 248 continue; 249 if (nlmclnt_reclaim(host, fl) != 0) 250 continue; 251 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); 252 if (host->h_nsmstate != nsmstate) { 253 /* Argh! The server rebooted again! */ 254 goto restart; 255 } 256 } 257 258 host->h_reclaiming = 0; 259 up_write(&host->h_rwsem); 260 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name); 261 262 /* Now, wake up all processes that sleep on a blocked lock */ 263 list_for_each_entry(block, &nlm_blocked, b_list) { 264 if (block->b_host == host) { 265 block->b_status = nlm_lck_denied_grace_period; 266 wake_up(&block->b_wait); 267 } 268 } 269 270 /* Release host handle after use */ 271 nlm_release_host(host); 272 lockd_down(); 273 unlock_kernel(); 274 return 0; 275 } 276