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