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/sunrpc/svc_xprt.h> 18 #include <linux/lockd/lockd.h> 19 #include <linux/kthread.h> 20 21 #include "trace.h" 22 23 #define NLMDBG_FACILITY NLMDBG_CLIENT 24 25 /* 26 * Local function prototypes 27 */ 28 static int reclaimer(void *ptr); 29 30 /* 31 * The following functions handle blocking and granting from the 32 * client perspective. 33 */ 34 35 static LIST_HEAD(nlm_blocked); 36 static DEFINE_SPINLOCK(nlm_blocked_lock); 37 38 /** 39 * nlmclnt_init - Set up per-NFS mount point lockd data structures 40 * @nlm_init: pointer to arguments structure 41 * 42 * Returns pointer to an appropriate nlm_host struct, 43 * or an ERR_PTR value. 44 */ 45 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init) 46 { 47 struct nlm_host *host; 48 u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4; 49 int status; 50 51 status = lockd_up(nlm_init->net, nlm_init->cred); 52 if (status < 0) 53 return ERR_PTR(status); 54 55 host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen, 56 nlm_init->protocol, nlm_version, 57 nlm_init->hostname, nlm_init->noresvport, 58 nlm_init->net, nlm_init->cred); 59 if (host == NULL) 60 goto out_nohost; 61 if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL) 62 goto out_nobind; 63 64 host->h_nlmclnt_ops = nlm_init->nlmclnt_ops; 65 return host; 66 out_nobind: 67 nlmclnt_release_host(host); 68 out_nohost: 69 lockd_down(nlm_init->net); 70 return ERR_PTR(-ENOLCK); 71 } 72 EXPORT_SYMBOL_GPL(nlmclnt_init); 73 74 /** 75 * nlmclnt_done - Release resources allocated by nlmclnt_init() 76 * @host: nlm_host structure reserved by nlmclnt_init() 77 * 78 */ 79 void nlmclnt_done(struct nlm_host *host) 80 { 81 struct net *net = host->net; 82 83 nlmclnt_release_host(host); 84 lockd_down(net); 85 } 86 EXPORT_SYMBOL_GPL(nlmclnt_done); 87 88 void nlmclnt_prepare_block(struct nlm_wait *block, struct nlm_host *host, struct file_lock *fl) 89 { 90 block->b_host = host; 91 block->b_lock = fl; 92 init_waitqueue_head(&block->b_wait); 93 block->b_status = nlm_lck_blocked; 94 } 95 96 struct rpc_clnt *nlmclnt_rpc_clnt(struct nlm_host *host) 97 { 98 return host->h_rpcclnt; 99 } 100 EXPORT_SYMBOL_GPL(nlmclnt_rpc_clnt); 101 102 /* 103 * Queue up a lock for blocking so that the GRANTED request can see it 104 */ 105 void nlmclnt_queue_block(struct nlm_wait *block) 106 { 107 spin_lock(&nlm_blocked_lock); 108 list_add(&block->b_list, &nlm_blocked); 109 spin_unlock(&nlm_blocked_lock); 110 } 111 112 /* 113 * Dequeue the block and return its final status 114 */ 115 __be32 nlmclnt_dequeue_block(struct nlm_wait *block) 116 { 117 __be32 status; 118 119 spin_lock(&nlm_blocked_lock); 120 list_del(&block->b_list); 121 status = block->b_status; 122 spin_unlock(&nlm_blocked_lock); 123 return status; 124 } 125 126 /* 127 * Block on a lock 128 */ 129 int nlmclnt_wait(struct nlm_wait *block, struct nlm_rqst *req, long timeout) 130 { 131 long ret; 132 133 /* A borken server might ask us to block even if we didn't 134 * request it. Just say no! 135 */ 136 if (block == NULL) 137 return -EAGAIN; 138 139 /* Go to sleep waiting for GRANT callback. Some servers seem 140 * to lose callbacks, however, so we're going to poll from 141 * time to time just to make sure. 142 * 143 * For now, the retry frequency is pretty high; normally 144 * a 1 minute timeout would do. See the comment before 145 * nlmclnt_lock for an explanation. 146 */ 147 ret = wait_event_interruptible_timeout(block->b_wait, 148 block->b_status != nlm_lck_blocked, 149 timeout); 150 if (ret < 0) 151 return -ERESTARTSYS; 152 /* Reset the lock status after a server reboot so we resend */ 153 if (block->b_status == nlm_lck_denied_grace_period) 154 block->b_status = nlm_lck_blocked; 155 return 0; 156 } 157 158 /* 159 * The server lockd has called us back to tell us the lock was granted 160 */ 161 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock) 162 { 163 const struct file_lock *fl = &lock->fl; 164 const struct nfs_fh *fh = &lock->fh; 165 struct nlm_wait *block; 166 __be32 res = nlm_lck_denied; 167 168 /* 169 * Look up blocked request based on arguments. 170 * Warning: must not use cookie to match it! 171 */ 172 spin_lock(&nlm_blocked_lock); 173 list_for_each_entry(block, &nlm_blocked, b_list) { 174 struct file_lock *fl_blocked = block->b_lock; 175 176 if (fl_blocked->fl_start != fl->fl_start) 177 continue; 178 if (fl_blocked->fl_end != fl->fl_end) 179 continue; 180 /* 181 * Careful! The NLM server will return the 32-bit "pid" that 182 * we put on the wire: in this case the lockowner "pid". 183 */ 184 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) 185 continue; 186 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr)) 187 continue; 188 if (nfs_compare_fh(NFS_FH(file_inode(fl_blocked->fl_file)), fh) != 0) 189 continue; 190 /* Alright, we found a lock. Set the return status 191 * and wake up the caller 192 */ 193 block->b_status = nlm_granted; 194 wake_up(&block->b_wait); 195 res = nlm_granted; 196 } 197 spin_unlock(&nlm_blocked_lock); 198 trace_nlmclnt_grant(lock, addr, svc_addr_len(addr), res); 199 return res; 200 } 201 202 /* 203 * The following procedures deal with the recovery of locks after a 204 * server crash. 205 */ 206 207 /* 208 * Reclaim all locks on server host. We do this by spawning a separate 209 * reclaimer thread. 210 */ 211 void 212 nlmclnt_recovery(struct nlm_host *host) 213 { 214 struct task_struct *task; 215 216 if (!host->h_reclaiming++) { 217 nlm_get_host(host); 218 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name); 219 if (IS_ERR(task)) 220 printk(KERN_ERR "lockd: unable to spawn reclaimer " 221 "thread. Locks for %s won't be reclaimed! " 222 "(%ld)\n", host->h_name, PTR_ERR(task)); 223 } 224 } 225 226 static int 227 reclaimer(void *ptr) 228 { 229 struct nlm_host *host = (struct nlm_host *) ptr; 230 struct nlm_wait *block; 231 struct nlm_rqst *req; 232 struct file_lock *fl, *next; 233 u32 nsmstate; 234 struct net *net = host->net; 235 236 req = kmalloc(sizeof(*req), GFP_KERNEL); 237 if (!req) 238 return 0; 239 240 allow_signal(SIGKILL); 241 242 down_write(&host->h_rwsem); 243 lockd_up(net, NULL); /* note: this cannot fail as lockd is already running */ 244 245 dprintk("lockd: reclaiming locks for host %s\n", host->h_name); 246 247 restart: 248 nsmstate = host->h_nsmstate; 249 250 /* Force a portmap getport - the peer's lockd will 251 * most likely end up on a different port. 252 */ 253 host->h_nextrebind = jiffies; 254 nlm_rebind_host(host); 255 256 /* First, reclaim all locks that have been granted. */ 257 list_splice_init(&host->h_granted, &host->h_reclaim); 258 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { 259 list_del_init(&fl->fl_u.nfs_fl.list); 260 261 /* 262 * sending this thread a SIGKILL will result in any unreclaimed 263 * locks being removed from the h_granted list. This means that 264 * the kernel will not attempt to reclaim them again if a new 265 * reclaimer thread is spawned for this host. 266 */ 267 if (signalled()) 268 continue; 269 if (nlmclnt_reclaim(host, fl, req) != 0) 270 continue; 271 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); 272 if (host->h_nsmstate != nsmstate) { 273 /* Argh! The server rebooted again! */ 274 goto restart; 275 } 276 } 277 278 host->h_reclaiming = 0; 279 up_write(&host->h_rwsem); 280 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name); 281 282 /* Now, wake up all processes that sleep on a blocked lock */ 283 spin_lock(&nlm_blocked_lock); 284 list_for_each_entry(block, &nlm_blocked, b_list) { 285 if (block->b_host == host) { 286 block->b_status = nlm_lck_denied_grace_period; 287 wake_up(&block->b_wait); 288 } 289 } 290 spin_unlock(&nlm_blocked_lock); 291 292 /* Release host handle after use */ 293 nlmclnt_release_host(host); 294 lockd_down(net); 295 kfree(req); 296 return 0; 297 } 298