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 u32 b_status; /* grant callback status */ 40 }; 41 42 static LIST_HEAD(nlm_blocked); 43 44 /* 45 * Queue up a lock for blocking so that the GRANTED request can see it 46 */ 47 int nlmclnt_prepare_block(struct nlm_rqst *req, struct nlm_host *host, struct file_lock *fl) 48 { 49 struct nlm_wait *block; 50 51 BUG_ON(req->a_block != NULL); 52 block = kmalloc(sizeof(*block), GFP_KERNEL); 53 if (block == NULL) 54 return -ENOMEM; 55 block->b_host = host; 56 block->b_lock = fl; 57 init_waitqueue_head(&block->b_wait); 58 block->b_status = NLM_LCK_BLOCKED; 59 60 list_add(&block->b_list, &nlm_blocked); 61 req->a_block = block; 62 63 return 0; 64 } 65 66 void nlmclnt_finish_block(struct nlm_rqst *req) 67 { 68 struct nlm_wait *block = req->a_block; 69 70 if (block == NULL) 71 return; 72 req->a_block = NULL; 73 list_del(&block->b_list); 74 kfree(block); 75 } 76 77 /* 78 * Block on a lock 79 */ 80 long nlmclnt_block(struct nlm_rqst *req, long timeout) 81 { 82 struct nlm_wait *block = req->a_block; 83 long ret; 84 85 /* A borken server might ask us to block even if we didn't 86 * request it. Just say no! 87 */ 88 if (!req->a_args.block) 89 return -EAGAIN; 90 91 /* Go to sleep waiting for GRANT callback. Some servers seem 92 * to lose callbacks, however, so we're going to poll from 93 * time to time just to make sure. 94 * 95 * For now, the retry frequency is pretty high; normally 96 * a 1 minute timeout would do. See the comment before 97 * nlmclnt_lock for an explanation. 98 */ 99 ret = wait_event_interruptible_timeout(block->b_wait, 100 block->b_status != NLM_LCK_BLOCKED, 101 timeout); 102 103 if (block->b_status != NLM_LCK_BLOCKED) { 104 req->a_res.status = block->b_status; 105 block->b_status = NLM_LCK_BLOCKED; 106 } 107 108 return ret; 109 } 110 111 /* 112 * The server lockd has called us back to tell us the lock was granted 113 */ 114 u32 115 nlmclnt_grant(struct nlm_lock *lock) 116 { 117 struct nlm_wait *block; 118 u32 res = nlm_lck_denied; 119 120 /* 121 * Look up blocked request based on arguments. 122 * Warning: must not use cookie to match it! 123 */ 124 list_for_each_entry(block, &nlm_blocked, b_list) { 125 if (nlm_compare_locks(block->b_lock, &lock->fl)) { 126 /* Alright, we found a lock. Set the return status 127 * and wake up the caller 128 */ 129 block->b_status = NLM_LCK_GRANTED; 130 wake_up(&block->b_wait); 131 res = nlm_granted; 132 } 133 } 134 return res; 135 } 136 137 /* 138 * The following procedures deal with the recovery of locks after a 139 * server crash. 140 */ 141 142 /* 143 * Mark the locks for reclaiming. 144 * FIXME: In 2.5 we don't want to iterate through any global file_lock_list. 145 * Maintain NLM lock reclaiming lists in the nlm_host instead. 146 */ 147 static 148 void nlmclnt_mark_reclaim(struct nlm_host *host) 149 { 150 struct file_lock *fl; 151 struct inode *inode; 152 struct list_head *tmp; 153 154 list_for_each(tmp, &file_lock_list) { 155 fl = list_entry(tmp, struct file_lock, fl_link); 156 157 inode = fl->fl_file->f_dentry->d_inode; 158 if (inode->i_sb->s_magic != NFS_SUPER_MAGIC) 159 continue; 160 if (fl->fl_u.nfs_fl.owner->host != host) 161 continue; 162 if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED)) 163 continue; 164 fl->fl_u.nfs_fl.flags |= NFS_LCK_RECLAIM; 165 } 166 } 167 168 /* 169 * Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number, 170 * that we mark locks for reclaiming, and that we bump the pseudo NSM state. 171 */ 172 static inline 173 void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate) 174 { 175 host->h_monitored = 0; 176 host->h_nsmstate = newstate; 177 host->h_state++; 178 host->h_nextrebind = 0; 179 nlm_rebind_host(host); 180 nlmclnt_mark_reclaim(host); 181 dprintk("NLM: reclaiming locks for host %s", host->h_name); 182 } 183 184 /* 185 * Reclaim all locks on server host. We do this by spawning a separate 186 * reclaimer thread. 187 */ 188 void 189 nlmclnt_recovery(struct nlm_host *host, u32 newstate) 190 { 191 if (host->h_reclaiming++) { 192 if (host->h_nsmstate == newstate) 193 return; 194 nlmclnt_prepare_reclaim(host, newstate); 195 } else { 196 nlmclnt_prepare_reclaim(host, newstate); 197 nlm_get_host(host); 198 __module_get(THIS_MODULE); 199 if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0) 200 module_put(THIS_MODULE); 201 } 202 } 203 204 static int 205 reclaimer(void *ptr) 206 { 207 struct nlm_host *host = (struct nlm_host *) ptr; 208 struct nlm_wait *block; 209 struct list_head *tmp; 210 struct file_lock *fl; 211 struct inode *inode; 212 213 daemonize("%s-reclaim", host->h_name); 214 allow_signal(SIGKILL); 215 216 /* This one ensures that our parent doesn't terminate while the 217 * reclaim is in progress */ 218 lock_kernel(); 219 lockd_up(); 220 221 /* First, reclaim all locks that have been marked. */ 222 restart: 223 list_for_each(tmp, &file_lock_list) { 224 fl = list_entry(tmp, struct file_lock, fl_link); 225 226 inode = fl->fl_file->f_dentry->d_inode; 227 if (inode->i_sb->s_magic != NFS_SUPER_MAGIC) 228 continue; 229 if (fl->fl_u.nfs_fl.owner->host != host) 230 continue; 231 if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM)) 232 continue; 233 234 fl->fl_u.nfs_fl.flags &= ~NFS_LCK_RECLAIM; 235 nlmclnt_reclaim(host, fl); 236 if (signalled()) 237 break; 238 goto restart; 239 } 240 241 host->h_reclaiming = 0; 242 243 /* Now, wake up all processes that sleep on a blocked lock */ 244 list_for_each_entry(block, &nlm_blocked, b_list) { 245 if (block->b_host == host) { 246 block->b_status = NLM_LCK_DENIED_GRACE_PERIOD; 247 wake_up(&block->b_wait); 248 } 249 } 250 251 /* Release host handle after use */ 252 nlm_release_host(host); 253 lockd_down(); 254 unlock_kernel(); 255 module_put_and_exit(0); 256 } 257