fs/lockd/clntlock.c

   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->c.flc_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 }