/* * linux/fs/lockd/clntlock.c * * Lock handling for the client side NLM implementation * * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de> */ #include <linux/module.h> #include <linux/types.h> #include <linux/time.h> #include <linux/nfs_fs.h> #include <linux/sunrpc/clnt.h> #include <linux/sunrpc/svc.h> #include <linux/lockd/lockd.h> #include <linux/smp_lock.h> #include <linux/kthread.h> #define NLMDBG_FACILITY NLMDBG_CLIENT /* * Local function prototypes */ static int reclaimer(void *ptr); /* * The following functions handle blocking and granting from the * client perspective. */ /* * This is the representation of a blocked client lock. */ struct nlm_wait { struct list_head b_list; /* linked list */ wait_queue_head_t b_wait; /* where to wait on */ struct nlm_host * b_host; struct file_lock * b_lock; /* local file lock */ unsigned short b_reclaim; /* got to reclaim lock */ __be32 b_status; /* grant callback status */ }; static LIST_HEAD(nlm_blocked); /** * nlmclnt_init - Set up per-NFS mount point lockd data structures * @nlm_init: pointer to arguments structure * * Returns pointer to an appropriate nlm_host struct, * or an ERR_PTR value. */ struct nlm_host *nlmclnt_init(const struct nlmclnt_initdata *nlm_init) { struct nlm_host *host; u32 nlm_version = (nlm_init->nfs_version == 2) ? 1 : 4; int status; status = lockd_up(); if (status < 0) return ERR_PTR(status); host = nlmclnt_lookup_host(nlm_init->address, nlm_init->addrlen, nlm_init->protocol, nlm_version, nlm_init->hostname, nlm_init->noresvport); if (host == NULL) { lockd_down(); return ERR_PTR(-ENOLCK); } return host; } EXPORT_SYMBOL_GPL(nlmclnt_init); /** * nlmclnt_done - Release resources allocated by nlmclnt_init() * @host: nlm_host structure reserved by nlmclnt_init() * */ void nlmclnt_done(struct nlm_host *host) { nlm_release_host(host); lockd_down(); } EXPORT_SYMBOL_GPL(nlmclnt_done); /* * Queue up a lock for blocking so that the GRANTED request can see it */ struct nlm_wait *nlmclnt_prepare_block(struct nlm_host *host, struct file_lock *fl) { struct nlm_wait *block; block = kmalloc(sizeof(*block), GFP_KERNEL); if (block != NULL) { block->b_host = host; block->b_lock = fl; init_waitqueue_head(&block->b_wait); block->b_status = nlm_lck_blocked; list_add(&block->b_list, &nlm_blocked); } return block; } void nlmclnt_finish_block(struct nlm_wait *block) { if (block == NULL) return; list_del(&block->b_list); kfree(block); } /* * Block on a lock */ int nlmclnt_block(struct nlm_wait *block, struct nlm_rqst *req, long timeout) { long ret; /* A borken server might ask us to block even if we didn't * request it. Just say no! */ if (block == NULL) return -EAGAIN; /* Go to sleep waiting for GRANT callback. Some servers seem * to lose callbacks, however, so we're going to poll from * time to time just to make sure. * * For now, the retry frequency is pretty high; normally * a 1 minute timeout would do. See the comment before * nlmclnt_lock for an explanation. */ ret = wait_event_interruptible_timeout(block->b_wait, block->b_status != nlm_lck_blocked, timeout); if (ret < 0) return -ERESTARTSYS; req->a_res.status = block->b_status; return 0; } /* * The server lockd has called us back to tell us the lock was granted */ __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock) { const struct file_lock *fl = &lock->fl; const struct nfs_fh *fh = &lock->fh; struct nlm_wait *block; __be32 res = nlm_lck_denied; /* * Look up blocked request based on arguments. * Warning: must not use cookie to match it! */ list_for_each_entry(block, &nlm_blocked, b_list) { struct file_lock *fl_blocked = block->b_lock; if (fl_blocked->fl_start != fl->fl_start) continue; if (fl_blocked->fl_end != fl->fl_end) continue; /* * Careful! The NLM server will return the 32-bit "pid" that * we put on the wire: in this case the lockowner "pid". */ if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid) continue; if (!rpc_cmp_addr(nlm_addr(block->b_host), addr)) continue; if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0) continue; /* Alright, we found a lock. Set the return status * and wake up the caller */ block->b_status = nlm_granted; wake_up(&block->b_wait); res = nlm_granted; } return res; } /* * The following procedures deal with the recovery of locks after a * server crash. */ /* * Reclaim all locks on server host. We do this by spawning a separate * reclaimer thread. */ void nlmclnt_recovery(struct nlm_host *host) { struct task_struct *task; if (!host->h_reclaiming++) { nlm_get_host(host); task = kthread_run(reclaimer, host, "%s-reclaim", host->h_name); if (IS_ERR(task)) printk(KERN_ERR "lockd: unable to spawn reclaimer " "thread. Locks for %s won't be reclaimed! " "(%ld)\n", host->h_name, PTR_ERR(task)); } } static int reclaimer(void *ptr) { struct nlm_host *host = (struct nlm_host *) ptr; struct nlm_wait *block; struct file_lock *fl, *next; u32 nsmstate; allow_signal(SIGKILL); down_write(&host->h_rwsem); /* This one ensures that our parent doesn't terminate while the * reclaim is in progress */ lock_kernel(); lockd_up(); /* note: this cannot fail as lockd is already running */ dprintk("lockd: reclaiming locks for host %s\n", host->h_name); restart: nsmstate = host->h_nsmstate; /* Force a portmap getport - the peer's lockd will * most likely end up on a different port. */ host->h_nextrebind = jiffies; nlm_rebind_host(host); /* First, reclaim all locks that have been granted. */ list_splice_init(&host->h_granted, &host->h_reclaim); list_for_each_entry_safe(fl, next, &host->h_reclaim, fl_u.nfs_fl.list) { list_del_init(&fl->fl_u.nfs_fl.list); /* * sending this thread a SIGKILL will result in any unreclaimed * locks being removed from the h_granted list. This means that * the kernel will not attempt to reclaim them again if a new * reclaimer thread is spawned for this host. */ if (signalled()) continue; if (nlmclnt_reclaim(host, fl) != 0) continue; list_add_tail(&fl->fl_u.nfs_fl.list, &host->h_granted); if (host->h_nsmstate != nsmstate) { /* Argh! The server rebooted again! */ goto restart; } } host->h_reclaiming = 0; up_write(&host->h_rwsem); dprintk("NLM: done reclaiming locks for host %s\n", host->h_name); /* Now, wake up all processes that sleep on a blocked lock */ list_for_each_entry(block, &nlm_blocked, b_list) { if (block->b_host == host) { block->b_status = nlm_lck_denied_grace_period; wake_up(&block->b_wait); } } /* Release host handle after use */ nlm_release_host(host); lockd_down(); unlock_kernel(); return 0; }