linux/fs/lockd/clntlock.c
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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/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 */
  24static 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 */
  34struct 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
  43static LIST_HEAD(nlm_blocked);
  44static 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 */
  53struct 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;
  73out_nobind:
  74        nlmclnt_release_host(host);
  75out_nohost:
  76        lockd_down(nlm_init->net);
  77        return ERR_PTR(-ENOLCK);
  78}
  79EXPORT_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 */
  86void nlmclnt_done(struct nlm_host *host)
  87{
  88        struct net *net = host->net;
  89
  90        nlmclnt_release_host(host);
  91        lockd_down(net);
  92}
  93EXPORT_SYMBOL_GPL(nlmclnt_done);
  94
  95/*
  96 * Queue up a lock for blocking so that the GRANTED request can see it
  97 */
  98struct 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
 116void 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 */
 129int 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 */
 211void
 212nlmclnt_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
 226static int
 227reclaimer(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
 251restart:
 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}
 302
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