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