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