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 /*
 143  * The server lockd has called us back to tell us the lock was granted
 144  */
 145 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
 146 {
 147         const struct file_lock *fl = &lock->fl;
 148         const struct nfs_fh *fh = &lock->fh;
 149         struct nlm_wait *block;
 150         __be32 res = nlm_lck_denied;
 151
 152         /*
 153          * Look up blocked request based on arguments.
 154          * Warning: must not use cookie to match it!
 155          */
 156         list_for_each_entry(block, &nlm_blocked, b_list) {
 157                 struct file_lock *fl_blocked = block->b_lock;
 158
 159                 if (fl_blocked->fl_start != fl->fl_start)
 160                         continue;
 161                 if (fl_blocked->fl_end != fl->fl_end)
 162                         continue;
 163                 /*
 164                  * Careful! The NLM server will return the 32-bit "pid" that
 165                  * we put on the wire: in this case the lockowner "pid".
 166                  */
 167                 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
 168                         continue;
 169                 if (!nlm_cmp_addr(nlm_addr(block->b_host), addr))
 170                         continue;
 171                 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
 172                         continue;
 173                 /* Alright, we found a lock. Set the return status
 174                  * and wake up the caller
 175                  */
 176                 block->b_status = nlm_granted;
 177                 wake_up(&block->b_wait);
 178                 res = nlm_granted;
 179         }
 180         return res;
 181 }
 182
 183 /*
 184  * The following procedures deal with the recovery of locks after a
 185  * server crash.
 186  */
 187
 188 /*
 189  * Reclaim all locks on server host. We do this by spawning a separate
 190  * reclaimer thread.
 191  */
 192 void
 193 nlmclnt_recovery(struct nlm_host *host)
 194 {
 195         struct task_struct *task;
 196
 197         if (!host->h_reclaiming++) {
 198                 nlm_get_host(host);
 199                 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
 200                 if (IS_ERR(task))
 201                         printk(KERN_ERR "lockd: unable to spawn reclaimer "
 202                                 "thread. Locks for %s won't be reclaimed! "
 203                                 "(%ld)\n", host->h_name, PTR_ERR(task));
 204         }
 205 }
 206
 207 static int
 208 reclaimer(void *ptr)
 209 {
 210         struct nlm_host   *host = (struct nlm_host *) ptr;
 211         struct nlm_wait   *block;
 212         struct file_lock *fl, *next;
 213         u32 nsmstate;
 214
 215         allow_signal(SIGKILL);
 216
 217         down_write(&host->h_rwsem);
 218
 219         /* This one ensures that our parent doesn't terminate while the
 220          * reclaim is in progress */
 221         lock_kernel();
 222         lockd_up();     /* note: this cannot fail as lockd is already running */
 223
 224         dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
 225
 226 restart:
 227         nsmstate = host->h_nsmstate;
 228
 229         /* Force a portmap getport - the peer's lockd will
 230          * most likely end up on a different port.
 231          */
 232         host->h_nextrebind = jiffies;
 233         nlm_rebind_host(host);
 234
 235         /* First, reclaim all locks that have been granted. */
 236         list_splice_init(&host->h_granted, &host->h_reclaim);
 237         list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
 238                 list_del_init(&fl->fl_u.nfs_fl.list);
 239
 240                 /*
 241                  * sending this thread a SIGKILL will result in any unreclaimed
 242                  * locks being removed from the h_granted list. This means that
 243                  * the kernel will not attempt to reclaim them again if a new
 244                  * reclaimer thread is spawned for this host.
 245                  */
 246                 if (signalled())
 247                         continue;
 248                 if (nlmclnt_reclaim(host, fl) != 0)
 249                         continue;
 250                 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
 251                 if (host->h_nsmstate != nsmstate) {
 252                         /* Argh! The server rebooted again! */
 253                         goto restart;
 254                 }
 255         }
 256
 257         host->h_reclaiming = 0;
 258         up_write(&host->h_rwsem);
 259         dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
 260
 261         /* Now, wake up all processes that sleep on a blocked lock */
 262         list_for_each_entry(block, &nlm_blocked, b_list) {
 263                 if (block->b_host == host) {
 264                         block->b_status = nlm_lck_denied_grace_period;
 265                         wake_up(&block->b_wait);
 266                 }
 267         }
 268
 269         /* Release host handle after use */
 270         nlm_release_host(host);
 271         lockd_down();
 272         unlock_kernel();
 273         return 0;
 274 }