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 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
  48 {
  49         struct nlm_wait *block;
  50
  51         block = kmalloc(sizeof(*block), GFP_KERNEL);
  52         if (block != NULL) {
  53                 block->b_host = host;
  54                 block->b_lock = fl;
  55                 init_waitqueue_head(&block->b_wait);
  56                 block->b_status = NLM_LCK_BLOCKED;
  57                 list_add(&block->b_list, &nlm_blocked);
  58         }
  59         return block;
  60 }
  61
  62 void nlmclnt_finish_block(struct nlm_wait *block)
  63 {
  64         if (block == NULL)
  65                 return;
  66         list_del(&block->b_list);
  67         kfree(block);
  68 }
  69
  70 /*
  71  * Block on a lock
  72  */
  73 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
  74 {
  75         long ret;
  76
  77         /* A borken server might ask us to block even if we didn't
  78          * request it. Just say no!
  79          */
  80         if (block == NULL)
  81                 return -EAGAIN;
  82
  83         /* Go to sleep waiting for GRANT callback. Some servers seem
  84          * to lose callbacks, however, so we're going to poll from
  85          * time to time just to make sure.
  86          *
  87          * For now, the retry frequency is pretty high; normally
  88          * a 1 minute timeout would do. See the comment before
  89          * nlmclnt_lock for an explanation.
  90          */
  91         ret = wait_event_interruptible_timeout(block->b_wait,
  92                         block->b_status != NLM_LCK_BLOCKED,
  93                         timeout);
  94         if (ret < 0)
  95                 return -ERESTARTSYS;
  96         req->a_res.status = block->b_status;
  97         return 0;
  98 }
  99
 100 /*
 101  * The server lockd has called us back to tell us the lock was granted
 102  */
 103 u32 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock)
 104 {
 105         const struct file_lock *fl = &lock->fl;
 106         const struct nfs_fh *fh = &lock->fh;
 107         struct nlm_wait *block;
 108         u32 res = nlm_lck_denied;
 109
 110         /*
 111          * Look up blocked request based on arguments.
 112          * Warning: must not use cookie to match it!
 113          */
 114         list_for_each_entry(block, &nlm_blocked, b_list) {
 115                 struct file_lock *fl_blocked = block->b_lock;
 116
 117                 if (fl_blocked->fl_start != fl->fl_start)
 118                         continue;
 119                 if (fl_blocked->fl_end != fl->fl_end)
 120                         continue;
 121                 /*
 122                  * Careful! The NLM server will return the 32-bit "pid" that
 123                  * we put on the wire: in this case the lockowner "pid".
 124                  */
 125                 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
 126                         continue;
 127                 if (!nlm_cmp_addr(&block->b_host->h_addr, addr))
 128                         continue;
 129                 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_dentry->d_inode) ,fh) != 0)
 130                         continue;
 131                 /* Alright, we found a lock. Set the return status
 132                  * and wake up the caller
 133                  */
 134                 block->b_status = NLM_LCK_GRANTED;
 135                 wake_up(&block->b_wait);
 136                 res = nlm_granted;
 137         }
 138         return res;
 139 }
 140
 141 /*
 142  * The following procedures deal with the recovery of locks after a
 143  * server crash.
 144  */
 145
 146 /*
 147  * Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number,
 148  * that we mark locks for reclaiming, and that we bump the pseudo NSM state.
 149  */
 150 static inline
 151 void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate)
 152 {
 153         host->h_monitored = 0;
 154         host->h_nsmstate = newstate;
 155         host->h_state++;
 156         host->h_nextrebind = 0;
 157         nlm_rebind_host(host);
 158
 159         /*
 160          * Mark the locks for reclaiming.
 161          */
 162         list_splice_init(&host->h_granted, &host->h_reclaim);
 163
 164         dprintk("NLM: reclaiming locks for host %s", host->h_name);
 165 }
 166
 167 /*
 168  * Reclaim all locks on server host. We do this by spawning a separate
 169  * reclaimer thread.
 170  */
 171 void
 172 nlmclnt_recovery(struct nlm_host *host, u32 newstate)
 173 {
 174         if (host->h_reclaiming++) {
 175                 if (host->h_nsmstate == newstate)
 176                         return;
 177                 nlmclnt_prepare_reclaim(host, newstate);
 178         } else {
 179                 nlmclnt_prepare_reclaim(host, newstate);
 180                 nlm_get_host(host);
 181                 __module_get(THIS_MODULE);
 182                 if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
 183                         module_put(THIS_MODULE);
 184         }
 185 }
 186
 187 static int
 188 reclaimer(void *ptr)
 189 {
 190         struct nlm_host   *host = (struct nlm_host *) ptr;
 191         struct nlm_wait   *block;
 192         struct file_lock *fl, *next;
 193
 194         daemonize("%s-reclaim", host->h_name);
 195         allow_signal(SIGKILL);
 196
 197         /* This one ensures that our parent doesn't terminate while the
 198          * reclaim is in progress */
 199         lock_kernel();
 200         lockd_up();
 201
 202         /* First, reclaim all locks that have been marked. */
 203 restart:
 204         list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
 205                 list_del_init(&fl->fl_u.nfs_fl.list);
 206
 207                 if (signalled())
 208                         continue;
 209                 if (nlmclnt_reclaim(host, fl) == 0)
 210                         list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
 211                 goto restart;
 212         }
 213
 214         host->h_reclaiming = 0;
 215
 216         /* Now, wake up all processes that sleep on a blocked lock */
 217         list_for_each_entry(block, &nlm_blocked, b_list) {
 218                 if (block->b_host == host) {
 219                         block->b_status = NLM_LCK_DENIED_GRACE_PERIOD;
 220                         wake_up(&block->b_wait);
 221                 }
 222         }
 223
 224         /* Release host handle after use */
 225         nlm_release_host(host);
 226         lockd_down();
 227         unlock_kernel();
 228         module_put_and_exit(0);
 229 }