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/slab.h>
  12 #include <linux/time.h>
  13 #include <linux/nfs_fs.h>
  14 #include <linux/sunrpc/addr.h>
  15 #include <linux/sunrpc/svc.h>
  16 #include <linux/lockd/lockd.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 static DEFINE_SPINLOCK(nlm_blocked_lock);
  45
  46 /**
  47  * nlmclnt_init - Set up per-NFS mount point lockd data structures
  48  * @nlm_init: pointer to arguments structure
  49  *
  50  * Returns pointer to an appropriate nlm_host struct,
  51  * or an ERR_PTR value.
  52  */
  53 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
  54 {
  55         struct nlm_host *host;
  56         u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
  57         int status;
  58
  59         status = lockd_up(nlm_init->net);
  60         if (status < 0)
  61                 return ERR_PTR(status);
  62
  63         host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen,
  64                                    nlm_init->protocol, nlm_version,
  65                                    nlm_init->hostname, nlm_init->noresvport,
  66                                    nlm_init->net);
  67         if (host == NULL)
  68                 goto out_nohost;
  69         if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL)
  70                 goto out_nobind;
  71
  72         host->h_nlmclnt_ops = nlm_init->nlmclnt_ops;
  73         return host;
  74 out_nobind:
  75         nlmclnt_release_host(host);
  76 out_nohost:
  77         lockd_down(nlm_init->net);
  78         return ERR_PTR(-ENOLCK);
  79 }
  80 EXPORT_SYMBOL_GPL(nlmclnt_init);
  81
  82 /**
  83  * nlmclnt_done - Release resources allocated by nlmclnt_init()
  84  * @host: nlm_host structure reserved by nlmclnt_init()
  85  *
  86  */
  87 void nlmclnt_done(struct nlm_host *host)
  88 {
  89         struct net *net = host->net;
  90
  91         nlmclnt_release_host(host);
  92         lockd_down(net);
  93 }
  94 EXPORT_SYMBOL_GPL(nlmclnt_done);
  95
  96 /*
  97  * Queue up a lock for blocking so that the GRANTED request can see it
  98  */
  99 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
 100 {
 101         struct nlm_wait *block;
 102
 103         block = kmalloc(sizeof(*block), GFP_KERNEL);
 104         if (block != NULL) {
 105                 block->b_host = host;
 106                 block->b_lock = fl;
 107                 init_waitqueue_head(&block->b_wait);
 108                 block->b_status = nlm_lck_blocked;
 109
 110                 spin_lock(&nlm_blocked_lock);
 111                 list_add(&block->b_list, &nlm_blocked);
 112                 spin_unlock(&nlm_blocked_lock);
 113         }
 114         return block;
 115 }
 116
 117 void nlmclnt_finish_block(struct nlm_wait *block)
 118 {
 119         if (block == NULL)
 120                 return;
 121         spin_lock(&nlm_blocked_lock);
 122         list_del(&block->b_list);
 123         spin_unlock(&nlm_blocked_lock);
 124         kfree(block);
 125 }
 126
 127 /*
 128  * Block on a lock
 129  */
 130 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
 131 {
 132         long ret;
 133
 134         /* A borken server might ask us to block even if we didn't
 135          * request it. Just say no!
 136          */
 137         if (block == NULL)
 138                 return -EAGAIN;
 139
 140         /* Go to sleep waiting for GRANT callback. Some servers seem
 141          * to lose callbacks, however, so we're going to poll from
 142          * time to time just to make sure.
 143          *
 144          * For now, the retry frequency is pretty high; normally
 145          * a 1 minute timeout would do. See the comment before
 146          * nlmclnt_lock for an explanation.
 147          */
 148         ret = wait_event_interruptible_timeout(block->b_wait,
 149                         block->b_status != nlm_lck_blocked,
 150                         timeout);
 151         if (ret < 0)
 152                 return -ERESTARTSYS;
 153         /* Reset the lock status after a server reboot so we resend */
 154         if (block->b_status == nlm_lck_denied_grace_period)
 155                 block->b_status = nlm_lck_blocked;
 156         req->a_res.status = block->b_status;
 157         return 0;
 158 }
 159
 160 /*
 161  * The server lockd has called us back to tell us the lock was granted
 162  */
 163 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
 164 {
 165         const struct file_lock *fl = &lock->fl;
 166         const struct nfs_fh *fh = &lock->fh;
 167         struct nlm_wait *block;
 168         __be32 res = nlm_lck_denied;
 169
 170         /*
 171          * Look up blocked request based on arguments.
 172          * Warning: must not use cookie to match it!
 173          */
 174         spin_lock(&nlm_blocked_lock);
 175         list_for_each_entry(block, &nlm_blocked, b_list) {
 176                 struct file_lock *fl_blocked = block->b_lock;
 177
 178                 if (fl_blocked->fl_start != fl->fl_start)
 179                         continue;
 180                 if (fl_blocked->fl_end != fl->fl_end)
 181                         continue;
 182                 /*
 183                  * Careful! The NLM server will return the 32-bit "pid" that
 184                  * we put on the wire: in this case the lockowner "pid".
 185                  */
 186                 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
 187                         continue;
 188                 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
 189                         continue;
 190                 if (nfs_compare_fh(NFS_FH(file_inode(fl_blocked->fl_file)) ,fh) != 0)
 191                         continue;
 192                 /* Alright, we found a lock. Set the return status
 193                  * and wake up the caller
 194                  */
 195                 block->b_status = nlm_granted;
 196                 wake_up(&block->b_wait);
 197                 res = nlm_granted;
 198         }
 199         spin_unlock(&nlm_blocked_lock);
 200         return res;
 201 }
 202
 203 /*
 204  * The following procedures deal with the recovery of locks after a
 205  * server crash.
 206  */
 207
 208 /*
 209  * Reclaim all locks on server host. We do this by spawning a separate
 210  * reclaimer thread.
 211  */
 212 void
 213 nlmclnt_recovery(struct nlm_host *host)
 214 {
 215         struct task_struct *task;
 216
 217         if (!host->h_reclaiming++) {
 218                 nlm_get_host(host);
 219                 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
 220                 if (IS_ERR(task))
 221                         printk(KERN_ERR "lockd: unable to spawn reclaimer "
 222                                 "thread. Locks for %s won't be reclaimed! "
 223                                 "(%ld)\n", host->h_name, PTR_ERR(task));
 224         }
 225 }
 226
 227 static int
 228 reclaimer(void *ptr)
 229 {
 230         struct nlm_host   *host = (struct nlm_host *) ptr;
 231         struct nlm_wait   *block;
 232         struct nlm_rqst   *req;
 233         struct file_lock *fl, *next;
 234         u32 nsmstate;
 235         struct net *net = host->net;
 236
 237         req = kmalloc(sizeof(*req), GFP_KERNEL);
 238         if (!req) {
 239                 printk(KERN_ERR "lockd: reclaimer unable to alloc memory."
 240                                 " Locks for %s won't be reclaimed!\n",
 241                                 host->h_name);
 242                 return 0;
 243         }
 244
 245         allow_signal(SIGKILL);
 246
 247         down_write(&host->h_rwsem);
 248         lockd_up(net);  /* note: this cannot fail as lockd is already running */
 249
 250         dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
 251
 252 restart:
 253         nsmstate = host->h_nsmstate;
 254
 255         /* Force a portmap getport - the peer's lockd will
 256          * most likely end up on a different port.
 257          */
 258         host->h_nextrebind = jiffies;
 259         nlm_rebind_host(host);
 260
 261         /* First, reclaim all locks that have been granted. */
 262         list_splice_init(&host->h_granted, &host->h_reclaim);
 263         list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
 264                 list_del_init(&fl->fl_u.nfs_fl.list);
 265
 266                 /*
 267                  * sending this thread a SIGKILL will result in any unreclaimed
 268                  * locks being removed from the h_granted list. This means that
 269                  * the kernel will not attempt to reclaim them again if a new
 270                  * reclaimer thread is spawned for this host.
 271                  */
 272                 if (signalled())
 273                         continue;
 274                 if (nlmclnt_reclaim(host, fl, req) != 0)
 275                         continue;
 276                 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
 277                 if (host->h_nsmstate != nsmstate) {
 278                         /* Argh! The server rebooted again! */
 279                         goto restart;
 280                 }
 281         }
 282
 283         host->h_reclaiming = 0;
 284         up_write(&host->h_rwsem);
 285         dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
 286
 287         /* Now, wake up all processes that sleep on a blocked lock */
 288         spin_lock(&nlm_blocked_lock);
 289         list_for_each_entry(block, &nlm_blocked, b_list) {
 290                 if (block->b_host == host) {
 291                         block->b_status = nlm_lck_denied_grace_period;
 292                         wake_up(&block->b_wait);
 293                 }
 294         }
 295         spin_unlock(&nlm_blocked_lock);
 296
 297         /* Release host handle after use */
 298         nlmclnt_release_host(host);
 299         lockd_down(net);
 300         kfree(req);
 301         return 0;
 302 }