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