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/time.h> 12 #include <linux/nfs_fs.h> 13 #include <linux/sunrpc/clnt.h> 14 #include <linux/sunrpc/svc.h> 15 #include <linux/lockd/lockd.h> 16 #include <linux/smp_lock.h> 17 18 #define NLMDBG_FACILITY NLMDBG_CLIENT 19 20 /* 21 * Local function prototypes 22 */ 23 static int reclaimer(void *ptr); 24 25 /* 26 * The following functions handle blocking and granting from the 27 * client perspective. 28 */ 29 30 /* 31 * This is the representation of a blocked client lock. 32 */ 33 struct nlm_wait { 34 struct list_head b_list; /* linked list */ 35 wait_queue_head_t b_wait; /* where to wait on */ 36 struct nlm_host * b_host; 37 struct file_lock * b_lock; /* local file lock */ 38 unsigned short b_reclaim; /* got to reclaim lock */ 39 __be32 b_status; /* grant callback status */ 40 }; 41 42 static LIST_HEAD(nlm_blocked); 43 44 /** 45 * nlmclnt_init - Set up per-NFS mount point lockd data structures 46 * @nlm_init: pointer to arguments structure 47 * 48 * Returns pointer to an appropriate nlm_host struct, 49 * or an ERR_PTR value. 50 */ 51 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init) 52 { 53 struct nlm_host *host; 54 u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4; 55 int status; 56 57 status = lockd_up(); 58 if (status < 0) 59 return ERR_PTR(status); 60 61 host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen, 62 nlm_init->protocol, nlm_version, 63 nlm_init->hostname); 64 if (host == NULL) { 65 lockd_down(); 66 return ERR_PTR(-ENOLCK); 67 } 68 69 return host; 70 } 71 EXPORT_SYMBOL_GPL(nlmclnt_init); 72 73 /** 74 * nlmclnt_done - Release resources allocated by nlmclnt_init() 75 * @host: nlm_host structure reserved by nlmclnt_init() 76 * 77 */ 78 void nlmclnt_done(struct nlm_host *host) 79 { 80 nlm_release_host(host); 81 lockd_down(); 82 } 83 EXPORT_SYMBOL_GPL(nlmclnt_done); 84 85 /* 86 * Queue up a lock for blocking so that the GRANTED request can see it 87 */ 88 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl) 89 { 90 struct nlm_wait *block; 91 92 block = kmalloc(sizeof(*block), GFP_KERNEL); 93 if (block != NULL) { 94 block->b_host = host; 95 block->b_lock = fl; 96 init_waitqueue_head(&block->b_wait); 97 block->b_status = nlm_lck_blocked; 98 list_add(&block->b_list, &nlm_blocked); 99 } 100 return block; 101 } 102 103 void nlmclnt_finish_block(struct nlm_wait *block) 104 { 105 if (block == NULL) 106 return; 107 list_del(&block->b_list); 108 kfree(block); 109 } 110 111 /* 112 * Block on a lock 113 */ 114 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout) 115 { 116 long ret; 117 118 /* A borken server might ask us to block even if we didn't 119 * request it. Just say no! 120 */ 121 if (block == NULL) 122 return -EAGAIN; 123 124 /* Go to sleep waiting for GRANT callback. Some servers seem 125 * to lose callbacks, however, so we're going to poll from 126 * time to time just to make sure. 127 * 128 * For now, the retry frequency is pretty high; normally 129 * a 1 minute timeout would do. See the comment before 130 * nlmclnt_lock for an explanation. 131 */ 132 ret = wait_event_interruptible_timeout(block->b_wait, 133 block->b_status != nlm_lck_blocked, 134 timeout); 135 if (ret < 0) 136 return -ERESTARTSYS; 137 req->a_res.status = block->b_status; 138 return 0; 139 } 140 141 /* 142 * The server lockd has called us back to tell us the lock was granted 143 */ 144 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock) 145 { 146 const struct file_lock *fl = &lock->fl; 147 const struct nfs_fh *fh = &lock->fh; 148 struct nlm_wait *block; 149 __be32 res = nlm_lck_denied; 150 151 /* 152 * Look up blocked request based on arguments. 153 * Warning: must not use cookie to match it! 154 */ 155 list_for_each_entry(block, &nlm_blocked, b_list) { 156 struct file_lock *fl_blocked = block->b_lock; 157 158 if (fl_blocked->fl_start != fl->fl_start) 159 continue; 160 if (fl_blocked->fl_end != fl->fl_end) 161 continue; 162 /* 163 * Careful! The NLM server will return the 32-bit "pid" that 164 * we put on the wire: in this case the lockowner "pid". 165 */ 166 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) 167 continue; 168 if (!nlm_cmp_addr(nlm_addr(block->b_host), addr)) 169 continue; 170 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0) 171 continue; 172 /* Alright, we found a lock. Set the return status 173 * and wake up the caller 174 */ 175 block->b_status = nlm_granted; 176 wake_up(&block->b_wait); 177 res = nlm_granted; 178 } 179 return res; 180 } 181 182 /* 183 * The following procedures deal with the recovery of locks after a 184 * server crash. 185 */ 186 187 /* 188 * Reclaim all locks on server host. We do this by spawning a separate 189 * reclaimer thread. 190 */ 191 void 192 nlmclnt_recovery(struct nlm_host *host) 193 { 194 if (!host->h_reclaiming++) { 195 nlm_get_host(host); 196 __module_get(THIS_MODULE); 197 if (kernel_thread(reclaimer, host, CLONE_FS | CLONE_FILES) < 0) 198 module_put(THIS_MODULE); 199 } 200 } 201 202 static int 203 reclaimer(void *ptr) 204 { 205 struct nlm_host *host = (struct nlm_host *) ptr; 206 struct nlm_wait *block; 207 struct file_lock *fl, *next; 208 u32 nsmstate; 209 210 daemonize("%s-reclaim", host->h_name); 211 allow_signal(SIGKILL); 212 213 down_write(&host->h_rwsem); 214 215 /* This one ensures that our parent doesn't terminate while the 216 * reclaim is in progress */ 217 lock_kernel(); 218 lockd_up(); /* note: this cannot fail as lockd is already running */ 219 220 dprintk("lockd: reclaiming locks for host %s\n", host->h_name); 221 222 restart: 223 nsmstate = host->h_nsmstate; 224 225 /* Force a portmap getport - the peer's lockd will 226 * most likely end up on a different port. 227 */ 228 host->h_nextrebind = jiffies; 229 nlm_rebind_host(host); 230 231 /* First, reclaim all locks that have been granted. */ 232 list_splice_init(&host->h_granted, &host->h_reclaim); 233 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { 234 list_del_init(&fl->fl_u.nfs_fl.list); 235 236 /* Why are we leaking memory here? --okir */ 237 if (signalled()) 238 continue; 239 if (nlmclnt_reclaim(host, fl) != 0) 240 continue; 241 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); 242 if (host->h_nsmstate != nsmstate) { 243 /* Argh! The server rebooted again! */ 244 goto restart; 245 } 246 } 247 248 host->h_reclaiming = 0; 249 up_write(&host->h_rwsem); 250 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name); 251 252 /* Now, wake up all processes that sleep on a blocked lock */ 253 list_for_each_entry(block, &nlm_blocked, b_list) { 254 if (block->b_host == host) { 255 block->b_status = nlm_lck_denied_grace_period; 256 wake_up(&block->b_wait); 257 } 258 } 259 260 /* Release host handle after use */ 261 nlm_release_host(host); 262 lockd_down(); 263 unlock_kernel(); 264 module_put_and_exit(0); 265 } 266