fs/lockd/clntlock.c

   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 #include <linux/kthread.h>
  18
  19 #define NLMDBG_FACILITY         NLMDBG_CLIENT
  20
  21 /*
  22  * Local function prototypes
  23  */
  24 static int                      reclaimer(void *ptr);
  25
  26 /*
  27  * The following functions handle blocking and granting from the
  28  * client perspective.
  29  */
  30
  31 /*
  32  * This is the representation of a blocked client lock.
  33  */
  34 struct nlm_wait {
  35         struct list_head        b_list;         /* linked list */
  36         wait_queue_head_t       b_wait;         /* where to wait on */
  37         struct nlm_host *       b_host;
  38         struct file_lock *      b_lock;         /* local file lock */
  39         unsigned short          b_reclaim;      /* got to reclaim lock */
  40         __be32                  b_status;       /* grant callback status */
  41 };
  42
  43 static LIST_HEAD(nlm_blocked);
  44
  45 /**
  46  * nlmclnt_init - Set up per-NFS mount point lockd data structures
  47  * @nlm_init: pointer to arguments structure
  48  *
  49  * Returns pointer to an appropriate nlm_host struct,
  50  * or an ERR_PTR value.
  51  */
  52 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
  53 {
  54         struct nlm_host *host;
  55         u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
  56         int status;
  57
  58         status = lockd_up();
  59         if (status < 0)
  60                 return ERR_PTR(status);
  61
  62         host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen,
  63                                    nlm_init->protocol, nlm_version,
  64                                    nlm_init->hostname, nlm_init->noresvport);
  65         if (host == NULL) {
  66                 lockd_down();
  67                 return ERR_PTR(-ENOLCK);
  68         }
  69
  70         return host;
  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         nlm_release_host(host);
  82         lockd_down();
  83 }
  84 EXPORT_SYMBOL_GPL(nlmclnt_done);
  85
  86 /*
  87  * Queue up a lock for blocking so that the GRANTED request can see it
  88  */
  89 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
  90 {
  91         struct nlm_wait *block;
  92
  93         block = kmalloc(sizeof(*block), GFP_KERNEL);
  94         if (block != NULL) {
  95                 block->b_host = host;
  96                 block->b_lock = fl;
  97                 init_waitqueue_head(&block->b_wait);
  98                 block->b_status = nlm_lck_blocked;
  99                 list_add(&block->b_list, &nlm_blocked);
 100         }
 101         return block;
 102 }
 103
 104 void nlmclnt_finish_block(struct nlm_wait *block)
 105 {
 106         if (block == NULL)
 107                 return;
 108         list_del(&block->b_list);
 109         kfree(block);
 110 }
 111
 112 /*
 113  * Block on a lock
 114  */
 115 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
 116 {
 117         long ret;
 118
 119         /* A borken server might ask us to block even if we didn't
 120          * request it. Just say no!
 121          */
 122         if (block == NULL)
 123                 return -EAGAIN;
 124
 125         /* Go to sleep waiting for GRANT callback. Some servers seem
 126          * to lose callbacks, however, so we're going to poll from
 127          * time to time just to make sure.
 128          *
 129          * For now, the retry frequency is pretty high; normally
 130          * a 1 minute timeout would do. See the comment before
 131          * nlmclnt_lock for an explanation.
 132          */
 133         ret = wait_event_interruptible_timeout(block->b_wait,
 134                         block->b_status != nlm_lck_blocked,
 135                         timeout);
 136         if (ret < 0)
 137                 return -ERESTARTSYS;
 138         req->a_res.status = block->b_status;
 139         return 0;
 140 }
 141
 142 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 143 static const struct in6_addr *nlmclnt_map_v4addr(const struct sockaddr *sap,
 144                                                  struct in6_addr *addr_mapped)
 145 {
 146         const struct sockaddr_in *sin = (const struct sockaddr_in *)sap;
 147
 148         switch (sap->sa_family) {
 149         case AF_INET6:
 150                 return &((const struct sockaddr_in6 *)sap)->sin6_addr;
 151         case AF_INET:
 152                 ipv6_addr_set_v4mapped(sin->sin_addr.s_addr, addr_mapped);
 153                 return addr_mapped;
 154         }
 155
 156         return NULL;
 157 }
 158
 159 /*
 160  * If lockd is using a PF_INET6 listener, all incoming requests appear
 161  * to come from AF_INET6 remotes.  The address of AF_INET remotes are
 162  * mapped to AF_INET6 automatically by the network layer.  In case the
 163  * user passed an AF_INET server address at mount time, ensure both
 164  * addresses are AF_INET6 before comparing them.
 165  */
 166 static int nlmclnt_cmp_addr(const struct nlm_host *host,
 167                             const struct sockaddr *sap)
 168 {
 169         const struct in6_addr *addr1;
 170         const struct in6_addr *addr2;
 171         struct in6_addr addr1_mapped;
 172         struct in6_addr addr2_mapped;
 173
 174         addr1 = nlmclnt_map_v4addr(nlm_addr(host), &addr1_mapped);
 175         if (likely(addr1 != NULL)) {
 176                 addr2 = nlmclnt_map_v4addr(sap, &addr2_mapped);
 177                 if (likely(addr2 != NULL))
 178                         return ipv6_addr_equal(addr1, addr2);
 179         }
 180
 181         return 0;
 182 }
 183 #else   /* !(CONFIG_IPV6 || CONFIG_IPV6_MODULE) */
 184 static int nlmclnt_cmp_addr(const struct nlm_host *host,
 185                             const struct sockaddr *sap)
 186 {
 187         return nlm_cmp_addr(nlm_addr(host), sap);
 188 }
 189 #endif  /* !(CONFIG_IPV6 || CONFIG_IPV6_MODULE) */
 190
 191 /*
 192  * The server lockd has called us back to tell us the lock was granted
 193  */
 194 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
 195 {
 196         const struct file_lock *fl = &lock->fl;
 197         const struct nfs_fh *fh = &lock->fh;
 198         struct nlm_wait *block;
 199         __be32 res = nlm_lck_denied;
 200
 201         /*
 202          * Look up blocked request based on arguments.
 203          * Warning: must not use cookie to match it!
 204          */
 205         list_for_each_entry(block, &nlm_blocked, b_list) {
 206                 struct file_lock *fl_blocked = block->b_lock;
 207
 208                 if (fl_blocked->fl_start != fl->fl_start)
 209                         continue;
 210                 if (fl_blocked->fl_end != fl->fl_end)
 211                         continue;
 212                 /*
 213                  * Careful! The NLM server will return the 32-bit "pid" that
 214                  * we put on the wire: in this case the lockowner "pid".
 215                  */
 216                 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
 217                         continue;
 218                 if (!nlmclnt_cmp_addr(block->b_host, addr))
 219                         continue;
 220                 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
 221                         continue;
 222                 /* Alright, we found a lock. Set the return status
 223                  * and wake up the caller
 224                  */
 225                 block->b_status = nlm_granted;
 226                 wake_up(&block->b_wait);
 227                 res = nlm_granted;
 228         }
 229         return res;
 230 }
 231
 232 /*
 233  * The following procedures deal with the recovery of locks after a
 234  * server crash.
 235  */
 236
 237 /*
 238  * Reclaim all locks on server host. We do this by spawning a separate
 239  * reclaimer thread.
 240  */
 241 void
 242 nlmclnt_recovery(struct nlm_host *host)
 243 {
 244         struct task_struct *task;
 245
 246         if (!host->h_reclaiming++) {
 247                 nlm_get_host(host);
 248                 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
 249                 if (IS_ERR(task))
 250                         printk(KERN_ERR "lockd: unable to spawn reclaimer "
 251                                 "thread. Locks for %s won't be reclaimed! "
 252                                 "(%ld)\n", host->h_name, PTR_ERR(task));
 253         }
 254 }
 255
 256 static int
 257 reclaimer(void *ptr)
 258 {
 259         struct nlm_host   *host = (struct nlm_host *) ptr;
 260         struct nlm_wait   *block;
 261         struct file_lock *fl, *next;
 262         u32 nsmstate;
 263
 264         allow_signal(SIGKILL);
 265
 266         down_write(&host->h_rwsem);
 267
 268         /* This one ensures that our parent doesn't terminate while the
 269          * reclaim is in progress */
 270         lock_kernel();
 271         lockd_up();     /* note: this cannot fail as lockd is already running */
 272
 273         dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
 274
 275 restart:
 276         nsmstate = host->h_nsmstate;
 277
 278         /* Force a portmap getport - the peer's lockd will
 279          * most likely end up on a different port.
 280          */
 281         host->h_nextrebind = jiffies;
 282         nlm_rebind_host(host);
 283
 284         /* First, reclaim all locks that have been granted. */
 285         list_splice_init(&host->h_granted, &host->h_reclaim);
 286         list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
 287                 list_del_init(&fl->fl_u.nfs_fl.list);
 288
 289                 /*
 290                  * sending this thread a SIGKILL will result in any unreclaimed
 291                  * locks being removed from the h_granted list. This means that
 292                  * the kernel will not attempt to reclaim them again if a new
 293                  * reclaimer thread is spawned for this host.
 294                  */
 295                 if (signalled())
 296                         continue;
 297                 if (nlmclnt_reclaim(host, fl) != 0)
 298                         continue;
 299                 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
 300                 if (host->h_nsmstate != nsmstate) {
 301                         /* Argh! The server rebooted again! */
 302                         goto restart;
 303                 }
 304         }
 305
 306         host->h_reclaiming = 0;
 307         up_write(&host->h_rwsem);
 308         dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
 309
 310         /* Now, wake up all processes that sleep on a blocked lock */
 311         list_for_each_entry(block, &nlm_blocked, b_list) {
 312                 if (block->b_host == host) {
 313                         block->b_status = nlm_lck_denied_grace_period;
 314                         wake_up(&block->b_wait);
 315                 }
 316         }
 317
 318         /* Release host handle after use */
 319         nlm_release_host(host);
 320         lockd_down();
 321         unlock_kernel();
 322         return 0;
 323 }