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   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 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock)
 115 {
 116         const struct file_lock *fl = &lock->fl;
 117         const struct nfs_fh *fh = &lock->fh;
 118         struct nlm_wait *block;
 119         u32 res = nlm_lck_denied;
 120
 121         /*
 122          * Look up blocked request based on arguments.
 123          * Warning: must not use cookie to match it!
 124          */
 125         list_for_each_entry(block, &nlm_blocked, b_list) {
 126                 struct file_lock *fl_blocked = block->b_lock;
 127
 128                 if (fl_blocked->fl_start != fl->fl_start)
 129                         continue;
 130                 if (fl_blocked->fl_end != fl->fl_end)
 131                         continue;
 132                 /*
 133                  * Careful! The NLM server will return the 32-bit "pid" that
 134                  * we put on the wire: in this case the lockowner "pid".
 135                  */
 136                 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
 137                         continue;
 138                 if (!nlm_cmp_addr(&block->b_host->h_addr, addr))
 139                         continue;
 140                 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_dentry->d_inode) ,fh) != 0)
 141                         continue;
 142                 /* Alright, we found a lock. Set the return status
 143                  * and wake up the caller
 144                  */
 145                 block->b_status = NLM_LCK_GRANTED;
 146                 wake_up(&block->b_wait);
 147                 res = nlm_granted;
 148         }
 149         return res;
 150 }
 151
 152 /*
 153  * The following procedures deal with the recovery of locks after a
 154  * server crash.
 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
 170         /*
 171          * Mark the locks for reclaiming.
 172          */
 173         list_splice_init(&host->h_granted, &host->h_reclaim);
 174
 175         dprintk("NLM: reclaiming locks for host %s", host->h_name);
 176 }
 177
 178 /*
 179  * Reclaim all locks on server host. We do this by spawning a separate
 180  * reclaimer thread.
 181  */
 182 void
 183 nlmclnt_recovery(struct nlm_host *host, u32 newstate)
 184 {
 185         if (host->h_reclaiming++) {
 186                 if (host->h_nsmstate == newstate)
 187                         return;
 188                 nlmclnt_prepare_reclaim(host, newstate);
 189         } else {
 190                 nlmclnt_prepare_reclaim(host, newstate);
 191                 nlm_get_host(host);
 192                 __module_get(THIS_MODULE);
 193                 if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
 194                         module_put(THIS_MODULE);
 195         }
 196 }
 197
 198 static int
 199 reclaimer(void *ptr)
 200 {
 201         struct nlm_host   *host = (struct nlm_host *) ptr;
 202         struct nlm_wait   *block;
 203         struct file_lock *fl, *next;
 204
 205         daemonize("%s-reclaim", host->h_name);
 206         allow_signal(SIGKILL);
 207
 208         /* This one ensures that our parent doesn't terminate while the
 209          * reclaim is in progress */
 210         lock_kernel();
 211         lockd_up();
 212
 213         /* First, reclaim all locks that have been marked. */
 214 restart:
 215         list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
 216                 list_del(&fl->fl_u.nfs_fl.list);
 217
 218                 nlmclnt_reclaim(host, fl);
 219                 if (signalled())
 220                         break;
 221                 goto restart;
 222         }
 223
 224         host->h_reclaiming = 0;
 225
 226         /* Now, wake up all processes that sleep on a blocked lock */
 227         list_for_each_entry(block, &nlm_blocked, b_list) {
 228                 if (block->b_host == host) {
 229                         block->b_status = NLM_LCK_DENIED_GRACE_PERIOD;
 230                         wake_up(&block->b_wait);
 231                 }
 232         }
 233
 234         /* Release host handle after use */
 235         nlm_release_host(host);
 236         lockd_down();
 237         unlock_kernel();
 238         module_put_and_exit(0);
 239 }