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/slab.h>
  12 #include <linux/time.h>
  13 #include <linux/nfs_fs.h>
  14 #include <linux/sunrpc/addr.h>
  15 #include <linux/sunrpc/svc.h>
  16 #include <linux/lockd/lockd.h>
  17 #include <linux/kthread.h>
  18
  19 #define NLMDBG_FACILITY         NLMDBG_CLIENT
  20
  21 /*
  22  * Local function prototypes
  23  */
  24 static int                      reclaimer(void *ptr);
  25
  26 /*
  27  * The following functions handle blocking and granting from the
  28  * client perspective.
  29  */
  30
  31 /*
  32  * This is the representation of a blocked client lock.
  33  */
  34 struct nlm_wait {
  35         struct list_head        b_list;         /* linked list */
  36         wait_queue_head_t       b_wait;         /* where to wait on */
  37         struct nlm_host *       b_host;
  38         struct file_lock *      b_lock;         /* local file lock */
  39         unsigned short          b_reclaim;      /* got to reclaim lock */
  40         __be32                  b_status;       /* grant callback status */
  41 };
  42
  43 static LIST_HEAD(nlm_blocked);
  44 static DEFINE_SPINLOCK(nlm_blocked_lock);
  45
  46 /**
  47  * nlmclnt_init - Set up per-NFS mount point lockd data structures
  48  * @nlm_init: pointer to arguments structure
  49  *
  50  * Returns pointer to an appropriate nlm_host struct,
  51  * or an ERR_PTR value.
  52  */
  53 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
  54 {
  55         struct nlm_host *host;
  56         u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
  57         int status;
  58
  59         status = lockd_up(nlm_init->net);
  60         if (status < 0)
  61                 return ERR_PTR(status);
  62
  63         host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen,
  64                                    nlm_init->protocol, nlm_version,
  65                                    nlm_init->hostname, nlm_init->noresvport,
  66                                    nlm_init->net);
  67         if (host == NULL)
  68                 goto out_nohost;
  69         if (host->h_rpcclnt == NULL && nlm_bind_host(host) == NULL)
  70                 goto out_nobind;
  71
  72         return host;
  73 out_nobind:
  74         nlmclnt_release_host(host);
  75 out_nohost:
  76         lockd_down(nlm_init->net);
  77         return ERR_PTR(-ENOLCK);
  78 }
  79 EXPORT_SYMBOL_GPL(nlmclnt_init);
  80
  81 /**
  82  * nlmclnt_done - Release resources allocated by nlmclnt_init()
  83  * @host: nlm_host structure reserved by nlmclnt_init()
  84  *
  85  */
  86 void nlmclnt_done(struct nlm_host *host)
  87 {
  88         struct net *net = host->net;
  89
  90         nlmclnt_release_host(host);
  91         lockd_down(net);
  92 }
  93 EXPORT_SYMBOL_GPL(nlmclnt_done);
  94
  95 /*
  96  * Queue up a lock for blocking so that the GRANTED request can see it
  97  */
  98 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
  99 {
 100         struct nlm_wait *block;
 101
 102         block = kmalloc(sizeof(*block), GFP_KERNEL);
 103         if (block != NULL) {
 104                 block->b_host = host;
 105                 block->b_lock = fl;
 106                 init_waitqueue_head(&block->b_wait);
 107                 block->b_status = nlm_lck_blocked;
 108
 109                 spin_lock(&nlm_blocked_lock);
 110                 list_add(&block->b_list, &nlm_blocked);
 111                 spin_unlock(&nlm_blocked_lock);
 112         }
 113         return block;
 114 }
 115
 116 void nlmclnt_finish_block(struct nlm_wait *block)
 117 {
 118         if (block == NULL)
 119                 return;
 120         spin_lock(&nlm_blocked_lock);
 121         list_del(&block->b_list);
 122         spin_unlock(&nlm_blocked_lock);
 123         kfree(block);
 124 }
 125
 126 /*
 127  * Block on a lock
 128  */
 129 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
 130 {
 131         long ret;
 132
 133         /* A borken server might ask us to block even if we didn't
 134          * request it. Just say no!
 135          */
 136         if (block == NULL)
 137                 return -EAGAIN;
 138
 139         /* Go to sleep waiting for GRANT callback. Some servers seem
 140          * to lose callbacks, however, so we're going to poll from
 141          * time to time just to make sure.
 142          *
 143          * For now, the retry frequency is pretty high; normally
 144          * a 1 minute timeout would do. See the comment before
 145          * nlmclnt_lock for an explanation.
 146          */
 147         ret = wait_event_interruptible_timeout(block->b_wait,
 148                         block->b_status != nlm_lck_blocked,
 149                         timeout);
 150         if (ret < 0)
 151                 return -ERESTARTSYS;
 152         /* Reset the lock status after a server reboot so we resend */
 153         if (block->b_status == nlm_lck_denied_grace_period)
 154                 block->b_status = nlm_lck_blocked;
 155         req->a_res.status = block->b_status;
 156         return 0;
 157 }
 158
 159 /*
 160  * The server lockd has called us back to tell us the lock was granted
 161  */
 162 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
 163 {
 164         const struct file_lock *fl = &lock->fl;
 165         const struct nfs_fh *fh = &lock->fh;
 166         struct nlm_wait *block;
 167         __be32 res = nlm_lck_denied;
 168
 169         /*
 170          * Look up blocked request based on arguments.
 171          * Warning: must not use cookie to match it!
 172          */
 173         spin_lock(&nlm_blocked_lock);
 174         list_for_each_entry(block, &nlm_blocked, b_list) {
 175                 struct file_lock *fl_blocked = block->b_lock;
 176
 177                 if (fl_blocked->fl_start != fl->fl_start)
 178                         continue;
 179                 if (fl_blocked->fl_end != fl->fl_end)
 180                         continue;
 181                 /*
 182                  * Careful! The NLM server will return the 32-bit "pid" that
 183                  * we put on the wire: in this case the lockowner "pid".
 184                  */
 185                 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
 186                         continue;
 187                 if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
 188                         continue;
 189                 if (nfs_compare_fh(NFS_FH(file_inode(fl_blocked->fl_file)) ,fh) != 0)
 190                         continue;
 191                 /* Alright, we found a lock. Set the return status
 192                  * and wake up the caller
 193                  */
 194                 block->b_status = nlm_granted;
 195                 wake_up(&block->b_wait);
 196                 res = nlm_granted;
 197         }
 198         spin_unlock(&nlm_blocked_lock);
 199         return res;
 200 }
 201
 202 /*
 203  * The following procedures deal with the recovery of locks after a
 204  * server crash.
 205  */
 206
 207 /*
 208  * Reclaim all locks on server host. We do this by spawning a separate
 209  * reclaimer thread.
 210  */
 211 void
 212 nlmclnt_recovery(struct nlm_host *host)
 213 {
 214         struct task_struct *task;
 215
 216         if (!host->h_reclaiming++) {
 217                 nlm_get_host(host);
 218                 task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name);
 219                 if (IS_ERR(task))
 220                         printk(KERN_ERR "lockd: unable to spawn reclaimer "
 221                                 "thread. Locks for %s won't be reclaimed! "
 222                                 "(%ld)\n", host->h_name, PTR_ERR(task));
 223         }
 224 }
 225
 226 static int
 227 reclaimer(void *ptr)
 228 {
 229         struct nlm_host   *host = (struct nlm_host *) ptr;
 230         struct nlm_wait   *block;
 231         struct nlm_rqst   *req;
 232         struct file_lock *fl, *next;
 233         u32 nsmstate;
 234         struct net *net = host->net;
 235
 236         req = kmalloc(sizeof(*req), GFP_KERNEL);
 237         if (!req) {
 238                 printk(KERN_ERR "lockd: reclaimer unable to alloc memory."
 239                                 " Locks for %s won't be reclaimed!\n",
 240                                 host->h_name);
 241                 return 0;
 242         }
 243
 244         allow_signal(SIGKILL);
 245
 246         down_write(&host->h_rwsem);
 247         lockd_up(net);  /* note: this cannot fail as lockd is already running */
 248
 249         dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
 250
 251 restart:
 252         nsmstate = host->h_nsmstate;
 253
 254         /* Force a portmap getport - the peer's lockd will
 255          * most likely end up on a different port.
 256          */
 257         host->h_nextrebind = jiffies;
 258         nlm_rebind_host(host);
 259
 260         /* First, reclaim all locks that have been granted. */
 261         list_splice_init(&host->h_granted, &host->h_reclaim);
 262         list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
 263                 list_del_init(&fl->fl_u.nfs_fl.list);
 264
 265                 /*
 266                  * sending this thread a SIGKILL will result in any unreclaimed
 267                  * locks being removed from the h_granted list. This means that
 268                  * the kernel will not attempt to reclaim them again if a new
 269                  * reclaimer thread is spawned for this host.
 270                  */
 271                 if (signalled())
 272                         continue;
 273                 if (nlmclnt_reclaim(host, fl, req) != 0)
 274                         continue;
 275                 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
 276                 if (host->h_nsmstate != nsmstate) {
 277                         /* Argh! The server rebooted again! */
 278                         goto restart;
 279                 }
 280         }
 281
 282         host->h_reclaiming = 0;
 283         up_write(&host->h_rwsem);
 284         dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
 285
 286         /* Now, wake up all processes that sleep on a blocked lock */
 287         spin_lock(&nlm_blocked_lock);
 288         list_for_each_entry(block, &nlm_blocked, b_list) {
 289                 if (block->b_host == host) {
 290                         block->b_status = nlm_lck_denied_grace_period;
 291                         wake_up(&block->b_wait);
 292                 }
 293         }
 294         spin_unlock(&nlm_blocked_lock);
 295
 296         /* Release host handle after use */
 297         nlmclnt_release_host(host);
 298         lockd_down(net);
 299         kfree(req);
 300         return 0;
 301 }