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  * nlmclnt_init - Set up per-NFS mount point lockd data structures
  46  * @nlm_init: pointer to arguments structure
  47  *
  48  * Returns pointer to an appropriate nlm_host struct,
  49  * or an ERR_PTR value.
  50  */
  51 struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init)
  52 {
  53         struct nlm_host *host;
  54         u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4;
  55         int status;
  56
  57         status = lockd_up();
  58         if (status < 0)
  59                 return ERR_PTR(status);
  60
  61         host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen,
  62                                    nlm_init->protocol, nlm_version,
  63                                    nlm_init->hostname);
  64         if (host == NULL) {
  65                 lockd_down();
  66                 return ERR_PTR(-ENOLCK);
  67         }
  68
  69         return host;
  70 }
  71 EXPORT_SYMBOL_GPL(nlmclnt_init);
  72
  73 /**
  74  * nlmclnt_done - Release resources allocated by nlmclnt_init()
  75  * @host: nlm_host structure reserved by nlmclnt_init()
  76  *
  77  */
  78 void nlmclnt_done(struct nlm_host *host)
  79 {
  80         nlm_release_host(host);
  81         lockd_down();
  82 }
  83 EXPORT_SYMBOL_GPL(nlmclnt_done);
  84
  85 /*
  86  * Queue up a lock for blocking so that the GRANTED request can see it
  87  */
  88 struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl)
  89 {
  90         struct nlm_wait *block;
  91
  92         block = kmalloc(sizeof(*block), GFP_KERNEL);
  93         if (block != NULL) {
  94                 block->b_host = host;
  95                 block->b_lock = fl;
  96                 init_waitqueue_head(&block->b_wait);
  97                 block->b_status = nlm_lck_blocked;
  98                 list_add(&block->b_list, &nlm_blocked);
  99         }
 100         return block;
 101 }
 102
 103 void nlmclnt_finish_block(struct nlm_wait *block)
 104 {
 105         if (block == NULL)
 106                 return;
 107         list_del(&block->b_list);
 108         kfree(block);
 109 }
 110
 111 /*
 112  * Block on a lock
 113  */
 114 int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout)
 115 {
 116         long ret;
 117
 118         /* A borken server might ask us to block even if we didn't
 119          * request it. Just say no!
 120          */
 121         if (block == NULL)
 122                 return -EAGAIN;
 123
 124         /* Go to sleep waiting for GRANT callback. Some servers seem
 125          * to lose callbacks, however, so we're going to poll from
 126          * time to time just to make sure.
 127          *
 128          * For now, the retry frequency is pretty high; normally
 129          * a 1 minute timeout would do. See the comment before
 130          * nlmclnt_lock for an explanation.
 131          */
 132         ret = wait_event_interruptible_timeout(block->b_wait,
 133                         block->b_status != nlm_lck_blocked,
 134                         timeout);
 135         if (ret < 0)
 136                 return -ERESTARTSYS;
 137         req->a_res.status = block->b_status;
 138         return 0;
 139 }
 140
 141 /*
 142  * The server lockd has called us back to tell us the lock was granted
 143  */
 144 __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
 145 {
 146         const struct file_lock *fl = &lock->fl;
 147         const struct nfs_fh *fh = &lock->fh;
 148         struct nlm_wait *block;
 149         __be32 res = nlm_lck_denied;
 150
 151         /*
 152          * Look up blocked request based on arguments.
 153          * Warning: must not use cookie to match it!
 154          */
 155         list_for_each_entry(block, &nlm_blocked, b_list) {
 156                 struct file_lock *fl_blocked = block->b_lock;
 157
 158                 if (fl_blocked->fl_start != fl->fl_start)
 159                         continue;
 160                 if (fl_blocked->fl_end != fl->fl_end)
 161                         continue;
 162                 /*
 163                  * Careful! The NLM server will return the 32-bit "pid" that
 164                  * we put on the wire: in this case the lockowner "pid".
 165                  */
 166                 if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
 167                         continue;
 168                 if (!nlm_cmp_addr(nlm_addr(block->b_host), addr))
 169                         continue;
 170                 if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
 171                         continue;
 172                 /* Alright, we found a lock. Set the return status
 173                  * and wake up the caller
 174                  */
 175                 block->b_status = nlm_granted;
 176                 wake_up(&block->b_wait);
 177                 res = nlm_granted;
 178         }
 179         return res;
 180 }
 181
 182 /*
 183  * The following procedures deal with the recovery of locks after a
 184  * server crash.
 185  */
 186
 187 /*
 188  * Reclaim all locks on server host. We do this by spawning a separate
 189  * reclaimer thread.
 190  */
 191 void
 192 nlmclnt_recovery(struct nlm_host *host)
 193 {
 194         if (!host->h_reclaiming++) {
 195                 nlm_get_host(host);
 196                 __module_get(THIS_MODULE);
 197                 if (kernel_thread(reclaimer, host, CLONE_FS | CLONE_FILES) < 0)
 198                         module_put(THIS_MODULE);
 199         }
 200 }
 201
 202 static int
 203 reclaimer(void *ptr)
 204 {
 205         struct nlm_host   *host = (struct nlm_host *) ptr;
 206         struct nlm_wait   *block;
 207         struct file_lock *fl, *next;
 208         u32 nsmstate;
 209
 210         daemonize("%s-reclaim", host->h_name);
 211         allow_signal(SIGKILL);
 212
 213         down_write(&host->h_rwsem);
 214
 215         /* This one ensures that our parent doesn't terminate while the
 216          * reclaim is in progress */
 217         lock_kernel();
 218         lockd_up();     /* note: this cannot fail as lockd is already running */
 219
 220         dprintk("lockd: reclaiming locks for host %s\n", host->h_name);
 221
 222 restart:
 223         nsmstate = host->h_nsmstate;
 224
 225         /* Force a portmap getport - the peer's lockd will
 226          * most likely end up on a different port.
 227          */
 228         host->h_nextrebind = jiffies;
 229         nlm_rebind_host(host);
 230
 231         /* First, reclaim all locks that have been granted. */
 232         list_splice_init(&host->h_granted, &host->h_reclaim);
 233         list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) {
 234                 list_del_init(&fl->fl_u.nfs_fl.list);
 235
 236                 /* Why are we leaking memory here? --okir */
 237                 if (signalled())
 238                         continue;
 239                 if (nlmclnt_reclaim(host, fl) != 0)
 240                         continue;
 241                 list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted);
 242                 if (host->h_nsmstate != nsmstate) {
 243                         /* Argh! The server rebooted again! */
 244                         goto restart;
 245                 }
 246         }
 247
 248         host->h_reclaiming = 0;
 249         up_write(&host->h_rwsem);
 250         dprintk("NLM: done reclaiming locks for host %s\n", host->h_name);
 251
 252         /* Now, wake up all processes that sleep on a blocked lock */
 253         list_for_each_entry(block, &nlm_blocked, b_list) {
 254                 if (block->b_host == host) {
 255                         block->b_status = nlm_lck_denied_grace_period;
 256                         wake_up(&block->b_wait);
 257                 }
 258         }
 259
 260         /* Release host handle after use */
 261         nlm_release_host(host);
 262         lockd_down();
 263         unlock_kernel();
 264         module_put_and_exit(0);
 265 }