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