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         __be32                  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 __be32 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         __be32 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_path.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_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  * Reclaim all locks on server host. We do this by spawning a separate
 148  * reclaimer thread.
 149  */
 150 void
 151 nlmclnt_recovery(struct nlm_host *host)
 152 {
 153         if (!host->h_reclaiming++) {
 154                 nlm_get_host(host);
 155                 __module_get(THIS_MODULE);
 156                 if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0)
 157                         module_put(THIS_MODULE);
 158         }
 159 }
 160
 161 static int
 162 reclaimer(void *ptr)
 163 {
 164         struct nlm_host   *host = (struct nlm_host *) ptr;
 165         struct nlm_wait   *block;
 166         struct file_lock *fl, *next;
 167         u32 nsmstate;
 168
 169         daemonize("%s-reclaim", host->h_name);
 170         allow_signal(SIGKILL);
 171
 172         down_write(&host->h_rwsem);
 173
 174         /* This one ensures that our parent doesn't terminate while the
 175          * reclaim is in progress */
 176         lock_kernel();
 177         lockd_up(0); /* note: this cannot fail as lockd is already running */
 178
 179         dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
 180
 181 restart:
 182         nsmstate = host->h_nsmstate;
 183
 184         /* Force a portmap getport - the peer's lockd will
 185          * most likely end up on a different port.
 186          */
 187         host->h_nextrebind = jiffies;
 188         nlm_rebind_host(host);
 189
 190         /* First, reclaim all locks that have been granted. */
 191         list_splice_init(&host->h_granted, &host->h_reclaim);
 192         list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
 193                 list_del_init(&fl->fl_u.nfs_fl.list);
 194
 195                 /* Why are we leaking memory here? --okir */
 196                 if (signalled())
 197                         continue;
 198                 if (nlmclnt_reclaim(host, fl) != 0)
 199                         continue;
 200                 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
 201                 if (host->h_nsmstate != nsmstate) {
 202                         /* Argh! The server rebooted again! */
 203                         goto restart;
 204                 }
 205         }
 206
 207         host->h_reclaiming = 0;
 208         up_write(&host->h_rwsem);
 209         dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
 210
 211         /* Now, wake up all processes that sleep on a blocked lock */
 212         list_for_each_entry(block, &nlm_blocked, b_list) {
 213                 if (block->b_host == host) {
 214                         block->b_status = nlm_lck_denied_grace_period;
 215                         wake_up(&block->b_wait);
 216                 }
 217         }
 218
 219         /* Release host handle after use */
 220         nlm_release_host(host);
 221         lockd_down();
 222         unlock_kernel();
 223         module_put_and_exit(0);
 224 }