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 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl) 48 { 49 struct nlm_wait *block; 50 51 block = kmalloc(sizeof(*block), GFP_KERNEL); 52 if (block != NULL) { 53 block->b_host = host; 54 block->b_lock = fl; 55 init_waitqueue_head(&block->b_wait); 56 block->b_status = NLM_LCK_BLOCKED; 57 list_add(&block->b_list, &nlm_blocked); 58 } 59 return block; 60 } 61 62 void nlmclnt_finish_block(struct nlm_wait *block) 63 { 64 if (block == NULL) 65 return; 66 list_del(&block->b_list); 67 kfree(block); 68 } 69 70 /* 71 * Block on a lock 72 */ 73 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout) 74 { 75 long ret; 76 77 /* A borken server might ask us to block even if we didn't 78 * request it. Just say no! 79 */ 80 if (block == NULL) 81 return -EAGAIN; 82 83 /* Go to sleep waiting for GRANT callback. Some servers seem 84 * to lose callbacks, however, so we're going to poll from 85 * time to time just to make sure. 86 * 87 * For now, the retry frequency is pretty high; normally 88 * a 1 minute timeout would do. See the comment before 89 * nlmclnt_lock for an explanation. 90 */ 91 ret = wait_event_interruptible_timeout(block->b_wait, 92 block->b_status != NLM_LCK_BLOCKED, 93 timeout); 94 if (ret < 0) 95 return -ERESTARTSYS; 96 req->a_res.status = block->b_status; 97 return 0; 98 } 99 100 /* 101 * The server lockd has called us back to tell us the lock was granted 102 */ 103 u32 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock) 104 { 105 const struct file_lock *fl = &lock->fl; 106 const struct nfs_fh *fh = &lock->fh; 107 struct nlm_wait *block; 108 u32 res = nlm_lck_denied; 109 110 /* 111 * Look up blocked request based on arguments. 112 * Warning: must not use cookie to match it! 113 */ 114 list_for_each_entry(block, &nlm_blocked, b_list) { 115 struct file_lock *fl_blocked = block->b_lock; 116 117 if (fl_blocked->fl_start != fl->fl_start) 118 continue; 119 if (fl_blocked->fl_end != fl->fl_end) 120 continue; 121 /* 122 * Careful! The NLM server will return the 32-bit "pid" that 123 * we put on the wire: in this case the lockowner "pid". 124 */ 125 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) 126 continue; 127 if (!nlm_cmp_addr(&block->b_host->h_addr, addr)) 128 continue; 129 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_dentry->d_inode) ,fh) != 0) 130 continue; 131 /* Alright, we found a lock. Set the return status 132 * and wake up the caller 133 */ 134 block->b_status = NLM_LCK_GRANTED; 135 wake_up(&block->b_wait); 136 res = nlm_granted; 137 } 138 return res; 139 } 140 141 /* 142 * The following procedures deal with the recovery of locks after a 143 * server crash. 144 */ 145 146 /* 147 * Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number, 148 * that we mark locks for reclaiming, and that we bump the pseudo NSM state. 149 */ 150 static inline 151 void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate) 152 { 153 host->h_monitored = 0; 154 host->h_nsmstate = newstate; 155 host->h_state++; 156 host->h_nextrebind = 0; 157 nlm_rebind_host(host); 158 159 /* 160 * Mark the locks for reclaiming. 161 */ 162 list_splice_init(&host->h_granted, &host->h_reclaim); 163 164 dprintk("NLM: reclaiming locks for host %s", host->h_name); 165 } 166 167 /* 168 * Reclaim all locks on server host. We do this by spawning a separate 169 * reclaimer thread. 170 */ 171 void 172 nlmclnt_recovery(struct nlm_host *host, u32 newstate) 173 { 174 if (host->h_reclaiming++) { 175 if (host->h_nsmstate == newstate) 176 return; 177 nlmclnt_prepare_reclaim(host, newstate); 178 } else { 179 nlmclnt_prepare_reclaim(host, newstate); 180 nlm_get_host(host); 181 __module_get(THIS_MODULE); 182 if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0) 183 module_put(THIS_MODULE); 184 } 185 } 186 187 static int 188 reclaimer(void *ptr) 189 { 190 struct nlm_host *host = (struct nlm_host *) ptr; 191 struct nlm_wait *block; 192 struct file_lock *fl, *next; 193 194 daemonize("%s-reclaim", host->h_name); 195 allow_signal(SIGKILL); 196 197 /* This one ensures that our parent doesn't terminate while the 198 * reclaim is in progress */ 199 lock_kernel(); 200 lockd_up(); 201 202 /* First, reclaim all locks that have been marked. */ 203 restart: 204 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { 205 list_del_init(&fl->fl_u.nfs_fl.list); 206 207 if (signalled()) 208 continue; 209 if (nlmclnt_reclaim(host, fl) == 0) 210 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); 211 goto restart; 212 } 213 214 host->h_reclaiming = 0; 215 216 /* Now, wake up all processes that sleep on a blocked lock */ 217 list_for_each_entry(block, &nlm_blocked, b_list) { 218 if (block->b_host == host) { 219 block->b_status = NLM_LCK_DENIED_GRACE_PERIOD; 220 wake_up(&block->b_wait); 221 } 222 } 223 224 /* Release host handle after use */ 225 nlm_release_host(host); 226 lockd_down(); 227 unlock_kernel(); 228 module_put_and_exit(0); 229 } 230