/* * 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> #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 */ u32 b_status; /* grant callback status */ }; static LIST_HEAD(nlm_blocked); /* * Queue up a lock for blocking so that the GRANTED request can see it */ int nlmclnt_prepare_block(struct nlm_rqst *req, struct nlm_host *host, struct file_lock *fl) { struct nlm_wait *block; BUG_ON(req->a_block != NULL); block = kmalloc(sizeof(*block), GFP_KERNEL); if (block == NULL) return -ENOMEM; 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); req->a_block = block; return 0; } void nlmclnt_finish_block(struct nlm_rqst *req) { struct nlm_wait *block = req->a_block; if (block == NULL) return; req->a_block = NULL; list_del(&block->b_list); kfree(block); } /* * Block on a lock */ long nlmclnt_block(struct nlm_rqst *req, long timeout) { struct nlm_wait *block = req->a_block; long ret; /* A borken server might ask us to block even if we didn't * request it. Just say no! */ if (!req->a_args.block) 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 (block->b_status != NLM_LCK_BLOCKED) { req->a_res.status = block->b_status; block->b_status = NLM_LCK_BLOCKED; } return ret; } /* * The server lockd has called us back to tell us the lock was granted */ u32 nlmclnt_grant(struct nlm_lock *lock) { struct nlm_wait *block; u32 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) { if (nlm_compare_locks(block->b_lock, &lock->fl)) { /* Alright, we found a lock. Set the return status * and wake up the caller */ block->b_status = NLM_LCK_GRANTED; wake_up(&block->b_wait); res = nlm_granted; } } return res; } /* * The following procedures deal with the recovery of locks after a * server crash. */ /* * Mark the locks for reclaiming. * FIXME: In 2.5 we don't want to iterate through any global file_lock_list. * Maintain NLM lock reclaiming lists in the nlm_host instead. */ static void nlmclnt_mark_reclaim(struct nlm_host *host) { struct file_lock *fl; struct inode *inode; struct list_head *tmp; list_for_each(tmp, &file_lock_list) { fl = list_entry(tmp, struct file_lock, fl_link); inode = fl->fl_file->f_dentry->d_inode; if (inode->i_sb->s_magic != NFS_SUPER_MAGIC) continue; if (fl->fl_u.nfs_fl.owner == NULL) continue; if (fl->fl_u.nfs_fl.owner->host != host) continue; if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_GRANTED)) continue; fl->fl_u.nfs_fl.flags |= NFS_LCK_RECLAIM; } } /* * Someone has sent us an SM_NOTIFY. Ensure we bind to the new port number, * that we mark locks for reclaiming, and that we bump the pseudo NSM state. */ static inline void nlmclnt_prepare_reclaim(struct nlm_host *host, u32 newstate) { host->h_monitored = 0; host->h_nsmstate = newstate; host->h_state++; host->h_nextrebind = 0; nlm_rebind_host(host); nlmclnt_mark_reclaim(host); dprintk("NLM: reclaiming locks for host %s", host->h_name); } /* * Reclaim all locks on server host. We do this by spawning a separate * reclaimer thread. */ void nlmclnt_recovery(struct nlm_host *host, u32 newstate) { if (host->h_reclaiming++) { if (host->h_nsmstate == newstate) return; nlmclnt_prepare_reclaim(host, newstate); } else { nlmclnt_prepare_reclaim(host, newstate); nlm_get_host(host); __module_get(THIS_MODULE); if (kernel_thread(reclaimer, host, CLONE_KERNEL) < 0) module_put(THIS_MODULE); } } static int reclaimer(void *ptr) { struct nlm_host *host = (struct nlm_host *) ptr; struct nlm_wait *block; struct list_head *tmp; struct file_lock *fl; struct inode *inode; daemonize("%s-reclaim", host->h_name); allow_signal(SIGKILL); /* This one ensures that our parent doesn't terminate while the * reclaim is in progress */ lock_kernel(); lockd_up(); /* First, reclaim all locks that have been marked. */ restart: list_for_each(tmp, &file_lock_list) { fl = list_entry(tmp, struct file_lock, fl_link); inode = fl->fl_file->f_dentry->d_inode; if (inode->i_sb->s_magic != NFS_SUPER_MAGIC) continue; if (fl->fl_u.nfs_fl.owner == NULL) continue; if (fl->fl_u.nfs_fl.owner->host != host) continue; if (!(fl->fl_u.nfs_fl.flags & NFS_LCK_RECLAIM)) continue; fl->fl_u.nfs_fl.flags &= ~NFS_LCK_RECLAIM; nlmclnt_reclaim(host, fl); if (signalled()) break; goto restart; } host->h_reclaiming = 0; /* 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(); module_put_and_exit(0); }