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