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 /* 97 * Queue up a lock for blocking so that the GRANTED request can see it 98 */ 99 void nlmclnt_queue_block(struct nlm_wait *block) 100 { 101 spin_lock(&nlm_blocked_lock); 102 list_add(&block->b_list, &nlm_blocked); 103 spin_unlock(&nlm_blocked_lock); 104 } 105 106 /* 107 * Dequeue the block and return its final status 108 */ 109 __be32 nlmclnt_dequeue_block(struct nlm_wait *block) 110 { 111 __be32 status; 112 113 spin_lock(&nlm_blocked_lock); 114 list_del(&block->b_list); 115 status = block->b_status; 116 spin_unlock(&nlm_blocked_lock); 117 return status; 118 } 119 120 /* 121 * Block on a lock 122 */ 123 int nlmclnt_wait(struct nlm_wait *block, struct nlm_rqst *req, long timeout) 124 { 125 long ret; 126 127 /* A borken server might ask us to block even if we didn't 128 * request it. Just say no! 129 */ 130 if (block == NULL) 131 return -EAGAIN; 132 133 /* Go to sleep waiting for GRANT callback. Some servers seem 134 * to lose callbacks, however, so we're going to poll from 135 * time to time just to make sure. 136 * 137 * For now, the retry frequency is pretty high; normally 138 * a 1 minute timeout would do. See the comment before 139 * nlmclnt_lock for an explanation. 140 */ 141 ret = wait_event_interruptible_timeout(block->b_wait, 142 block->b_status != nlm_lck_blocked, 143 timeout); 144 if (ret < 0) 145 return -ERESTARTSYS; 146 /* Reset the lock status after a server reboot so we resend */ 147 if (block->b_status == nlm_lck_denied_grace_period) 148 block->b_status = nlm_lck_blocked; 149 return 0; 150 } 151 152 /* 153 * The server lockd has called us back to tell us the lock was granted 154 */ 155 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock) 156 { 157 const struct file_lock *fl = &lock->fl; 158 const struct nfs_fh *fh = &lock->fh; 159 struct nlm_wait *block; 160 __be32 res = nlm_lck_denied; 161 162 /* 163 * Look up blocked request based on arguments. 164 * Warning: must not use cookie to match it! 165 */ 166 spin_lock(&nlm_blocked_lock); 167 list_for_each_entry(block, &nlm_blocked, b_list) { 168 struct file_lock *fl_blocked = block->b_lock; 169 170 if (fl_blocked->fl_start != fl->fl_start) 171 continue; 172 if (fl_blocked->fl_end != fl->fl_end) 173 continue; 174 /* 175 * Careful! The NLM server will return the 32-bit "pid" that 176 * we put on the wire: in this case the lockowner "pid". 177 */ 178 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) 179 continue; 180 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr)) 181 continue; 182 if (nfs_compare_fh(NFS_FH(file_inode(fl_blocked->fl_file)), fh) != 0) 183 continue; 184 /* Alright, we found a lock. Set the return status 185 * and wake up the caller 186 */ 187 block->b_status = nlm_granted; 188 wake_up(&block->b_wait); 189 res = nlm_granted; 190 } 191 spin_unlock(&nlm_blocked_lock); 192 trace_nlmclnt_grant(lock, addr, svc_addr_len(addr), res); 193 return res; 194 } 195 196 /* 197 * The following procedures deal with the recovery of locks after a 198 * server crash. 199 */ 200 201 /* 202 * Reclaim all locks on server host. We do this by spawning a separate 203 * reclaimer thread. 204 */ 205 void 206 nlmclnt_recovery(struct nlm_host *host) 207 { 208 struct task_struct *task; 209 210 if (!host->h_reclaiming++) { 211 nlm_get_host(host); 212 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name); 213 if (IS_ERR(task)) 214 printk(KERN_ERR "lockd: unable to spawn reclaimer " 215 "thread. Locks for %s won't be reclaimed! " 216 "(%ld)\n", host->h_name, PTR_ERR(task)); 217 } 218 } 219 220 static int 221 reclaimer(void *ptr) 222 { 223 struct nlm_host *host = (struct nlm_host *) ptr; 224 struct nlm_wait *block; 225 struct nlm_rqst *req; 226 struct file_lock *fl, *next; 227 u32 nsmstate; 228 struct net *net = host->net; 229 230 req = kmalloc(sizeof(*req), GFP_KERNEL); 231 if (!req) 232 return 0; 233 234 allow_signal(SIGKILL); 235 236 down_write(&host->h_rwsem); 237 lockd_up(net, NULL); /* note: this cannot fail as lockd is already running */ 238 239 dprintk("lockd: reclaiming locks for host %s\n", host->h_name); 240 241 restart: 242 nsmstate = host->h_nsmstate; 243 244 /* Force a portmap getport - the peer's lockd will 245 * most likely end up on a different port. 246 */ 247 host->h_nextrebind = jiffies; 248 nlm_rebind_host(host); 249 250 /* First, reclaim all locks that have been granted. */ 251 list_splice_init(&host->h_granted, &host->h_reclaim); 252 list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { 253 list_del_init(&fl->fl_u.nfs_fl.list); 254 255 /* 256 * sending this thread a SIGKILL will result in any unreclaimed 257 * locks being removed from the h_granted list. This means that 258 * the kernel will not attempt to reclaim them again if a new 259 * reclaimer thread is spawned for this host. 260 */ 261 if (signalled()) 262 continue; 263 if (nlmclnt_reclaim(host, fl, req) != 0) 264 continue; 265 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); 266 if (host->h_nsmstate != nsmstate) { 267 /* Argh! The server rebooted again! */ 268 goto restart; 269 } 270 } 271 272 host->h_reclaiming = 0; 273 up_write(&host->h_rwsem); 274 dprintk("NLM: done reclaiming locks for host %s\n", host->h_name); 275 276 /* Now, wake up all processes that sleep on a blocked lock */ 277 spin_lock(&nlm_blocked_lock); 278 list_for_each_entry(block, &nlm_blocked, b_list) { 279 if (block->b_host == host) { 280 block->b_status = nlm_lck_denied_grace_period; 281 wake_up(&block->b_wait); 282 } 283 } 284 spin_unlock(&nlm_blocked_lock); 285 286 /* Release host handle after use */ 287 nlmclnt_release_host(host); 288 lockd_down(net); 289 kfree(req); 290 return 0; 291 } 292