1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/fs/lockd/clntlock.c 4 * 5 * Lock handling for the client side NLM implementation 6 * 7 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de> 8 */ 9 10 #include <linux/module.h> 11 #include <linux/types.h> 12 #include <linux/slab.h> 13 #include <linux/time.h> 14 #include <linux/nfs_fs.h> 15 #include <linux/sunrpc/addr.h> 16 #include <linux/sunrpc/svc.h> 17 #include <linux/lockd/lockd.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 static DEFINE_SPINLOCK(nlm_blocked_lock); 46 47 /** 48 * nlmclnt_init - Set up per-NFS mount point lockd data structures 49 * @nlm_init: pointer to arguments structure 50 * 51 * Returns pointer to an appropriate nlm_host struct, 52 * or an ERR_PTR value. 53 */ 54 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init) 55 { 56 struct nlm_host *host; 57 u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4; 58 int status; 59 60 status = lockd_up(nlm_init->net, nlm_init->cred); 61 if (status < 0) 62 return ERR_PTR(status); 63 64 host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen, 65 nlm_init->protocol, nlm_version, 66 nlm_init->hostname, nlm_init->noresvport, 67 nlm_init->net, nlm_init->cred); 68 if (host == NULL) 69 goto out_nohost; 70 if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL) 71 goto out_nobind; 72 73 host->h_nlmclnt_ops = nlm_init->nlmclnt_ops; 74 return host; 75 out_nobind: 76 nlmclnt_release_host(host); 77 out_nohost: 78 lockd_down(nlm_init->net); 79 return ERR_PTR(-ENOLCK); 80 } 81 EXPORT_SYMBOL_GPL(nlmclnt_init); 82 83 /** 84 * nlmclnt_done - Release resources allocated by nlmclnt_init() 85 * @host: nlm_host structure reserved by nlmclnt_init() 86 * 87 */ 88 void nlmclnt_done(struct nlm_host *host) 89 { 90 struct net *net = host->net; 91 92 nlmclnt_release_host(host); 93 lockd_down(net); 94 } 95 EXPORT_SYMBOL_GPL(nlmclnt_done); 96 97 /* 98 * Queue up a lock for blocking so that the GRANTED request can see it 99 */ 100 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl) 101 { 102 struct nlm_wait *block; 103 104 block = kmalloc(sizeof(*block), GFP_KERNEL); 105 if (block != NULL) { 106 block->b_host = host; 107 block->b_lock = fl; 108 init_waitqueue_head(&block->b_wait); 109 block->b_status = nlm_lck_blocked; 110 111 spin_lock(&nlm_blocked_lock); 112 list_add(&block->b_list, &nlm_blocked); 113 spin_unlock(&nlm_blocked_lock); 114 } 115 return block; 116 } 117 118 void nlmclnt_finish_block(struct nlm_wait *block) 119 { 120 if (block == NULL) 121 return; 122 spin_lock(&nlm_blocked_lock); 123 list_del(&block->b_list); 124 spin_unlock(&nlm_blocked_lock); 125 kfree(block); 126 } 127 128 /* 129 * Block on a lock 130 */ 131 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout) 132 { 133 long ret; 134 135 /* A borken server might ask us to block even if we didn't 136 * request it. Just say no! 137 */ 138 if (block == NULL) 139 return -EAGAIN; 140 141 /* Go to sleep waiting for GRANT callback. Some servers seem 142 * to lose callbacks, however, so we're going to poll from 143 * time to time just to make sure. 144 * 145 * For now, the retry frequency is pretty high; normally 146 * a 1 minute timeout would do. See the comment before 147 * nlmclnt_lock for an explanation. 148 */ 149 ret = wait_event_interruptible_timeout(block->b_wait, 150 block->b_status != nlm_lck_blocked, 151 timeout); 152 if (ret < 0) 153 return -ERESTARTSYS; 154 /* Reset the lock status after a server reboot so we resend */ 155 if (block->b_status == nlm_lck_denied_grace_period) 156 block->b_status = nlm_lck_blocked; 157 req->a_res.status = block->b_status; 158 return 0; 159 } 160 161 /* 162 * The server lockd has called us back to tell us the lock was granted 163 */ 164 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock) 165 { 166 const struct file_lock *fl = &lock->fl; 167 const struct nfs_fh *fh = &lock->fh; 168 struct nlm_wait *block; 169 __be32 res = nlm_lck_denied; 170 171 /* 172 * Look up blocked request based on arguments. 173 * Warning: must not use cookie to match it! 174 */ 175 spin_lock(&nlm_blocked_lock); 176 list_for_each_entry(block, &nlm_blocked, b_list) { 177 struct file_lock *fl_blocked = block->b_lock; 178 179 if (fl_blocked->fl_start != fl->fl_start) 180 continue; 181 if (fl_blocked->fl_end != fl->fl_end) 182 continue; 183 /* 184 * Careful! The NLM server will return the 32-bit "pid" that 185 * we put on the wire: in this case the lockowner "pid". 186 */ 187 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) 188 continue; 189 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr)) 190 continue; 191 if (nfs_compare_fh(NFS_FH(file_inode(fl_blocked->fl_file)), fh) != 0) 192 continue; 193 /* Alright, we found a lock. Set the return status 194 * and wake up the caller 195 */ 196 block->b_status = nlm_granted; 197 wake_up(&block->b_wait); 198 res = nlm_granted; 199 } 200 spin_unlock(&nlm_blocked_lock); 201 return res; 202 } 203 204 /* 205 * The following procedures deal with the recovery of locks after a 206 * server crash. 207 */ 208 209 /* 210 * Reclaim all locks on server host. We do this by spawning a separate 211 * reclaimer thread. 212 */ 213 void 214 nlmclnt_recovery(struct nlm_host *host) 215 { 216 struct task_struct *task; 217 218 if (!host->h_reclaiming++) { 219 nlm_get_host(host); 220 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name); 221 if (IS_ERR(task)) 222 printk(KERN_ERR "lockd: unable to spawn reclaimer " 223 "thread. Locks for %s won't be reclaimed! " 224 "(%ld)\n", host->h_name, PTR_ERR(task)); 225 } 226 } 227 228 static int 229 reclaimer(void *ptr) 230 { 231 struct nlm_host *host = (struct nlm_host *) ptr; 232 struct nlm_wait *block; 233 struct nlm_rqst *req; 234 struct file_lock *fl, *next; 235 u32 nsmstate; 236 struct net *net = host->net; 237 238 req = kmalloc(sizeof(*req), GFP_KERNEL); 239 if (!req) 240 return 0; 241 242 allow_signal(SIGKILL); 243 244 down_write(&host->h_rwsem); 245 lockd_up(net, NULL); /* note: this cannot fail as lockd is already running */ 246 247 dprintk("lockd: reclaiming locks for host %s\n", host->h_name); 248 249 restart: 250 nsmstate = host->h_nsmstate; 251 252 /* Force a portmap getport - the peer's lockd will 253 * most likely end up on a different port. 254 */ 255 host->h_nextrebind = jiffies; 256 nlm_rebind_host(host); 257 258 /* First, reclaim all locks that have been granted. */ 259 list_splice_init(&host->h_granted, &host->h_reclaim); 260 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { 261 list_del_init(&fl->fl_u.nfs_fl.list); 262 263 /* 264 * sending this thread a SIGKILL will result in any unreclaimed 265 * locks being removed from the h_granted list. This means that 266 * the kernel will not attempt to reclaim them again if a new 267 * reclaimer thread is spawned for this host. 268 */ 269 if (signalled()) 270 continue; 271 if (nlmclnt_reclaim(host, fl, req) != 0) 272 continue; 273 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); 274 if (host->h_nsmstate != nsmstate) { 275 /* Argh! The server rebooted again! */ 276 goto restart; 277 } 278 } 279 280 host->h_reclaiming = 0; 281 up_write(&host->h_rwsem); 282 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name); 283 284 /* Now, wake up all processes that sleep on a blocked lock */ 285 spin_lock(&nlm_blocked_lock); 286 list_for_each_entry(block, &nlm_blocked, b_list) { 287 if (block->b_host == host) { 288 block->b_status = nlm_lck_denied_grace_period; 289 wake_up(&block->b_wait); 290 } 291 } 292 spin_unlock(&nlm_blocked_lock); 293 294 /* Release host handle after use */ 295 nlmclnt_release_host(host); 296 lockd_down(net); 297 kfree(req); 298 return 0; 299 } 300