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 list_head        b_list;         /* 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 LIST_HEAD(nlm_blocked);
  43
  44 /*
  45  * Queue up a lock for blocking so that the GRANTED request can see it
  46  */
  47 int nlmclnt_prepare_block(struct nlm_rqst *req, struct nlm_host *host, struct file_lock *fl)
  48 {
  49         struct nlm_wait *block;
  50
  51         BUG_ON(req->a_block != NULL);
  52         block = kmalloc(sizeof(*block), GFP_KERNEL);
  53         if (block == NULL)
  54                 return -ENOMEM;
  55         block->b_host = host;
  56         block->b_lock = fl;
  57         init_waitqueue_head(&block->b_wait);
  58         block->b_status = NLM_LCK_BLOCKED;
  59
  60         list_add(&block->b_list, &nlm_blocked);
  61         req->a_block = block;
  62
  63         return 0;
  64 }
  65
  66 void nlmclnt_finish_block(struct nlm_rqst *req)
  67 {
  68         struct nlm_wait *block = req->a_block;
  69
  70         if (block == NULL)
  71                 return;
  72         req->a_block = NULL;
  73         list_del(&block->b_list);
  74         kfree(block);
  75 }
  76
  77 /*
  78  * Block on a lock
  79  */
  80 long nlmclnt_block(struct nlm_rqst *req, long timeout)
  81 {
  82         struct nlm_wait *block = req->a_block;
  83         long ret;
  84
  85         /* A borken server might ask us to block even if we didn't
  86          * request it. Just say no!
  87          */
  88         if (!req->a_args.block)
  89                 return -EAGAIN;
  90
  91         /* Go to sleep waiting for GRANT callback. Some servers seem
  92          * to lose callbacks, however, so we're going to poll from
  93          * time to time just to make sure.
  94          *
  95          * For now, the retry frequency is pretty high; normally
  96          * a 1 minute timeout would do. See the comment before
  97          * nlmclnt_lock for an explanation.
  98          */
  99         ret = wait_event_interruptible_timeout(block->b_wait,
 100                         block->b_status != NLM_LCK_BLOCKED,
 101                         timeout);
 102
 103         if (block->b_status != NLM_LCK_BLOCKED) {
 104                 req->a_res.status = block->b_status;
 105                 block->b_status = NLM_LCK_BLOCKED;
 106         }
 107
 108         return ret;
 109 }
 110
 111 /*
 112  * The server lockd has called us back to tell us the lock was granted
 113  */
 114 u32
 115 nlmclnt_grant(struct nlm_lock *lock)
 116 {
 117         struct nlm_wait *block;
 118         u32 res = nlm_lck_denied;
 119
 120         /*
 121          * Look up blocked request based on arguments.
 122          * Warning: must not use cookie to match it!
 123          */
 124         list_for_each_entry(block, &nlm_blocked, b_list) {
 125                 if (nlm_compare_locks(block->b_lock, &lock->fl)) {
 126                         /* Alright, we found a lock. Set the return status
 127                          * and wake up the caller
 128                          */
 129                         block->b_status = NLM_LCK_GRANTED;
 130                         wake_up(&block->b_wait);
 131                         res = nlm_granted;
 132                 }
 133         }
 134         return res;
 135 }
 136
 137 /*
 138  * The following procedures deal with the recovery of locks after a
 139  * server crash.
 140  */
 141
 142 /*
 143  * Mark the locks for reclaiming.
 144  * FIXME: In 2.5 we don't want to iterate through any global file_lock_list.
 145  *        Maintain NLM lock reclaiming lists in the nlm_host instead.
 146  */
 147 static
 148 void nlmclnt_mark_reclaim(struct nlm_host *host)
 149 {
 150         struct file_lock *fl;
 151         struct inode *inode;
 152         struct list_head *tmp;
 153
 154         list_for_each(tmp, &file_lock_list) {
 155                 fl = list_entry(tmp, struct file_lock, fl_link);
 156
 157                 inode = fl->fl_file->f_dentry->d_inode;
 158                 if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
 159                         continue;
 160                 if (fl->fl_u.nfs_fl.owner->host != host)
 161                         continue;
 162                 if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED))
 163                         continue;
 164                 fl->fl_u.nfs_fl.flags |= NFS_LCK_RECLAIM;
 165         }
 166 }
 167
 168 /*
 169  * Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number,
 170  * that we mark locks for reclaiming, and that we bump the pseudo NSM state.
 171  */
 172 static inline
 173 void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate)
 174 {
 175         host->h_monitored = 0;
 176         host->h_nsmstate = newstate;
 177         host->h_state++;
 178         host->h_nextrebind = 0;
 179         nlm_rebind_host(host);
 180         nlmclnt_mark_reclaim(host);
 181         dprintk("NLM: reclaiming locks for host %s", host->h_name);
 182 }
 183
 184 /*
 185  * Reclaim all locks on server host. We do this by spawning a separate
 186  * reclaimer thread.
 187  */
 188 void
 189 nlmclnt_recovery(struct nlm_host *host, u32 newstate)
 190 {
 191         if (host->h_reclaiming++) {
 192                 if (host->h_nsmstate == newstate)
 193                         return;
 194                 nlmclnt_prepare_reclaim(host, newstate);
 195         } else {
 196                 nlmclnt_prepare_reclaim(host, newstate);
 197                 nlm_get_host(host);
 198                 __module_get(THIS_MODULE);
 199                 if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
 200                         module_put(THIS_MODULE);
 201         }
 202 }
 203
 204 static int
 205 reclaimer(void *ptr)
 206 {
 207         struct nlm_host   *host = (struct nlm_host *) ptr;
 208         struct nlm_wait   *block;
 209         struct list_head *tmp;
 210         struct file_lock *fl;
 211         struct inode *inode;
 212
 213         daemonize("%s-reclaim", host->h_name);
 214         allow_signal(SIGKILL);
 215
 216         /* This one ensures that our parent doesn't terminate while the
 217          * reclaim is in progress */
 218         lock_kernel();
 219         lockd_up();
 220
 221         /* First, reclaim all locks that have been marked. */
 222 restart:
 223         list_for_each(tmp, &file_lock_list) {
 224                 fl = list_entry(tmp, struct file_lock, fl_link);
 225
 226                 inode = fl->fl_file->f_dentry->d_inode;
 227                 if (inode->i_sb->s_magic != NFS_SUPER_MAGIC)
 228                         continue;
 229                 if (fl->fl_u.nfs_fl.owner->host != host)
 230                         continue;
 231                 if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM))
 232                         continue;
 233
 234                 fl->fl_u.nfs_fl.flags &= ~NFS_LCK_RECLAIM;
 235                 nlmclnt_reclaim(host, fl);
 236                 if (signalled())
 237                         break;
 238                 goto restart;
 239         }
 240
 241         host->h_reclaiming = 0;
 242
 243         /* Now, wake up all processes that sleep on a blocked lock */
 244         list_for_each_entry(block, &nlm_blocked, b_list) {
 245                 if (block->b_host == host) {
 246                         block->b_status = NLM_LCK_DENIED_GRACE_PERIOD;
 247                         wake_up(&block->b_wait);
 248                 }
 249         }
 250
 251         /* Release host handle after use */
 252         nlm_release_host(host);
 253         lockd_down();
 254         unlock_kernel();
 255         module_put_and_exit(0);
 256 }