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
  18 #define NLMDBG_FACILITY         NLMDBG_CLIENT
  19
  20 /*
  21  * Local function prototypes
  22  */
  23 static int                      reclaimer(void *ptr);
  24
  25 /*
  26  * The following functions handle blocking and granting from the
  27  * client perspective.
  28  */
  29
  30 /*
  31  * This is the representation of a blocked client lock.
  32  */
  33 struct nlm_wait {
  34         struct nlm_wait *       b_next;         /* linked list */
  35         wait_queue_head_t       b_wait;         /* where to wait on */
  36         struct nlm_host *       b_host;
  37         struct file_lock *      b_lock;         /* local file lock */
  38         unsigned short          b_reclaim;      /* got to reclaim lock */
  39         u32                     b_status;       /* grant callback status */
  40 };
  41
  42 static struct nlm_wait *        nlm_blocked;
  43
  44 /*
  45  * Block on a lock
  46  */
  47 int
  48 nlmclnt_block(struct nlm_host *host, struct file_lock *fl, u32 *statp)
  49 {
  50         struct nlm_wait block, **head;
  51         int             err;
  52         u32             pstate;
  53
  54         block.b_host   = host;
  55         block.b_lock   = fl;
  56         init_waitqueue_head(&block.b_wait);
  57         block.b_status = NLM_LCK_BLOCKED;
  58         block.b_next   = nlm_blocked;
  59         nlm_blocked    = &block;
  60
  61         /* Remember pseudo nsm state */
  62         pstate = host->h_state;
  63
  64         /* Go to sleep waiting for GRANT callback. Some servers seem
  65          * to lose callbacks, however, so we're going to poll from
  66          * time to time just to make sure.
  67          *
  68          * For now, the retry frequency is pretty high; normally
  69          * a 1 minute timeout would do. See the comment before
  70          * nlmclnt_lock for an explanation.
  71          */
  72         sleep_on_timeout(&block.b_wait, 30*HZ);
  73
  74         for (head = &nlm_blocked; *head; head = &(*head)->b_next) {
  75                 if (*head == &block) {
  76                         *head = block.b_next;
  77                         break;
  78                 }
  79         }
  80
  81         if (!signalled()) {
  82                 *statp = block.b_status;
  83                 return 0;
  84         }
  85
  86         /* Okay, we were interrupted. Cancel the pending request
  87          * unless the server has rebooted.
  88          */
  89         if (pstate == host->h_state && (err = nlmclnt_cancel(host, fl)) < 0)
  90                 printk(KERN_NOTICE
  91                         "lockd: CANCEL call failed (errno %d)\n", -err);
  92
  93         return -ERESTARTSYS;
  94 }
  95
  96 /*
  97  * The server lockd has called us back to tell us the lock was granted
  98  */
  99 u32
 100 nlmclnt_grant(struct nlm_lock *lock)
 101 {
 102         struct nlm_wait *block;
 103
 104         /*
 105          * Look up blocked request based on arguments.
 106          * Warning: must not use cookie to match it!
 107          */
 108         for (block = nlm_blocked; block; block = block->b_next) {
 109                 if (nlm_compare_locks(block->b_lock, &lock->fl))
 110                         break;
 111         }
 112
 113         /* Ooops, no blocked request found. */
 114         if (block == NULL)
 115                 return nlm_lck_denied;
 116
 117         /* Alright, we found the lock. Set the return status and
 118          * wake up the caller.
 119          */
 120         block->b_status = NLM_LCK_GRANTED;
 121         wake_up(&block->b_wait);
 122
 123         return nlm_granted;
 124 }
 125
 126 /*
 127  * The following procedures deal with the recovery of locks after a
 128  * server crash.
 129  */
 130
 131 /*
 132  * Mark the locks for reclaiming.
 133  * FIXME: In 2.5 we don't want to iterate through any global file_lock_list.
 134  *        Maintain NLM lock reclaiming lists in the nlm_host instead.
 135  */
 136 static
 137 void nlmclnt_mark_reclaim(struct nlm_host *host)
 138 {
 139         struct file_lock *fl;
 140         struct inode *inode;
 141         struct list_head *tmp;
 142
 143         list_for_each(tmp, &file_lock_list) {
 144                 fl = list_entry(tmp, struct file_lock, fl_link);
 145
 146                 inode = fl->fl_file->f_dentry->d_inode;
 147                 if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
 148                         continue;
 149                 if (fl->fl_u.nfs_fl.owner->host != host)
 150                         continue;
 151                 if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED))
 152                         continue;
 153                 fl->fl_u.nfs_fl.flags |= NFS_LCK_RECLAIM;
 154         }
 155 }
 156
 157 /*
 158  * Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number,
 159  * that we mark locks for reclaiming, and that we bump the pseudo NSM state.
 160  */
 161 static inline
 162 void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate)
 163 {
 164         host->h_monitored = 0;
 165         host->h_nsmstate = newstate;
 166         host->h_state++;
 167         host->h_nextrebind = 0;
 168         nlm_rebind_host(host);
 169         nlmclnt_mark_reclaim(host);
 170         dprintk("NLM: reclaiming locks for host %s", host->h_name);
 171 }
 172
 173 /*
 174  * Reclaim all locks on server host. We do this by spawning a separate
 175  * reclaimer thread.
 176  */
 177 void
 178 nlmclnt_recovery(struct nlm_host *host, u32 newstate)
 179 {
 180         if (host->h_reclaiming++) {
 181                 if (host->h_nsmstate == newstate)
 182                         return;
 183                 nlmclnt_prepare_reclaim(host, newstate);
 184         } else {
 185                 nlmclnt_prepare_reclaim(host, newstate);
 186                 nlm_get_host(host);
 187                 __module_get(THIS_MODULE);
 188                 if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
 189                         module_put(THIS_MODULE);
 190         }
 191 }
 192
 193 static int
 194 reclaimer(void *ptr)
 195 {
 196         struct nlm_host   *host = (struct nlm_host *) ptr;
 197         struct nlm_wait   *block;
 198         struct list_head *tmp;
 199         struct file_lock *fl;
 200         struct inode *inode;
 201
 202         daemonize("%s-reclaim", host->h_name);
 203         allow_signal(SIGKILL);
 204
 205         /* This one ensures that our parent doesn't terminate while the
 206          * reclaim is in progress */
 207         lock_kernel();
 208         lockd_up();
 209
 210         /* First, reclaim all locks that have been marked. */
 211 restart:
 212         list_for_each(tmp, &file_lock_list) {
 213                 fl = list_entry(tmp, struct file_lock, fl_link);
 214
 215                 inode = fl->fl_file->f_dentry->d_inode;
 216                 if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
 217                         continue;
 218                 if (fl->fl_u.nfs_fl.owner->host != host)
 219                         continue;
 220                 if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM))
 221                         continue;
 222
 223                 fl->fl_u.nfs_fl.flags &= ~NFS_LCK_RECLAIM;
 224                 nlmclnt_reclaim(host, fl);
 225                 if (signalled())
 226                         break;
 227                 goto restart;
 228         }
 229
 230         host->h_reclaiming = 0;
 231
 232         /* Now, wake up all processes that sleep on a blocked lock */
 233         for (block = nlm_blocked; block; block = block->b_next) {
 234                 if (block->b_host == host) {
 235                         block->b_status = NLM_LCK_DENIED_GRACE_PERIOD;
 236                         wake_up(&block->b_wait);
 237                 }
 238         }
 239
 240         /* Release host handle after use */
 241         nlm_release_host(host);
 242         lockd_down();
 243         unlock_kernel();
 244         module_put_and_exit(0);
 245 }