/* * linux/fs/lockd/clntproc.c * * RPC procedures for the client side NLM implementation * * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de> */ #include <linux/module.h> #include <linux/smp_lock.h> #include <linux/types.h> #include <linux/errno.h> #include <linux/fs.h> #include <linux/nfs_fs.h> #include <linux/utsname.h> #include <linux/freezer.h> #include <linux/sunrpc/clnt.h> #include <linux/sunrpc/svc.h> #include <linux/lockd/lockd.h> #define NLMDBG_FACILITY NLMDBG_CLIENT #define NLMCLNT_GRACE_WAIT (5*HZ) #define NLMCLNT_POLL_TIMEOUT (30*HZ) #define NLMCLNT_MAX_RETRIES 3 static int nlmclnt_test(struct nlm_rqst *, struct file_lock *); static int nlmclnt_lock(struct nlm_rqst *, struct file_lock *); static int nlmclnt_unlock(struct nlm_rqst *, struct file_lock *); static int nlm_stat_to_errno(__be32 stat); static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host); static int nlmclnt_cancel(struct nlm_host *, int , struct file_lock *); static const struct rpc_call_ops nlmclnt_unlock_ops; static const struct rpc_call_ops nlmclnt_cancel_ops; /* * Cookie counter for NLM requests */ static atomic_t nlm_cookie = ATOMIC_INIT(0x1234); void nlmclnt_next_cookie(struct nlm_cookie *c) { u32 cookie = atomic_inc_return(&nlm_cookie); memcpy(c->data, &cookie, 4); c->len=4; } static struct nlm_lockowner *nlm_get_lockowner(struct nlm_lockowner *lockowner) { atomic_inc(&lockowner->count); return lockowner; } static void nlm_put_lockowner(struct nlm_lockowner *lockowner) { if (!atomic_dec_and_lock(&lockowner->count, &lockowner->host->h_lock)) return; list_del(&lockowner->list); spin_unlock(&lockowner->host->h_lock); nlm_release_host(lockowner->host); kfree(lockowner); } static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid) { struct nlm_lockowner *lockowner; list_for_each_entry(lockowner, &host->h_lockowners, list) { if (lockowner->pid == pid) return -EBUSY; } return 0; } static inline uint32_t __nlm_alloc_pid(struct nlm_host *host) { uint32_t res; do { res = host->h_pidcount++; } while (nlm_pidbusy(host, res) < 0); return res; } static struct nlm_lockowner *__nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner) { struct nlm_lockowner *lockowner; list_for_each_entry(lockowner, &host->h_lockowners, list) { if (lockowner->owner != owner) continue; return nlm_get_lockowner(lockowner); } return NULL; } static struct nlm_lockowner *nlm_find_lockowner(struct nlm_host *host, fl_owner_t owner) { struct nlm_lockowner *res, *new = NULL; spin_lock(&host->h_lock); res = __nlm_find_lockowner(host, owner); if (res == NULL) { spin_unlock(&host->h_lock); new = kmalloc(sizeof(*new), GFP_KERNEL); spin_lock(&host->h_lock); res = __nlm_find_lockowner(host, owner); if (res == NULL && new != NULL) { res = new; atomic_set(&new->count, 1); new->owner = owner; new->pid = __nlm_alloc_pid(host); new->host = nlm_get_host(host); list_add(&new->list, &host->h_lockowners); new = NULL; } } spin_unlock(&host->h_lock); kfree(new); return res; } /* * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls */ static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl) { struct nlm_args *argp = &req->a_args; struct nlm_lock *lock = &argp->lock; nlmclnt_next_cookie(&argp->cookie); memcpy(&lock->fh, NFS_FH(fl->fl_file->f_path.dentry->d_inode), sizeof(struct nfs_fh)); lock->caller = utsname()->nodename; lock->oh.data = req->a_owner; lock->oh.len = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s", (unsigned int)fl->fl_u.nfs_fl.owner->pid, utsname()->nodename); lock->svid = fl->fl_u.nfs_fl.owner->pid; lock->fl.fl_start = fl->fl_start; lock->fl.fl_end = fl->fl_end; lock->fl.fl_type = fl->fl_type; } static void nlmclnt_release_lockargs(struct nlm_rqst *req) { BUG_ON(req->a_args.lock.fl.fl_ops != NULL); } /** * nlmclnt_proc - Perform a single client-side lock request * @host: address of a valid nlm_host context representing the NLM server * @cmd: fcntl-style file lock operation to perform * @fl: address of arguments for the lock operation * */ int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl) { struct nlm_rqst *call; int status; nlm_get_host(host); call = nlm_alloc_call(host); if (call == NULL) return -ENOMEM; nlmclnt_locks_init_private(fl, host); /* Set up the argument struct */ nlmclnt_setlockargs(call, fl); lock_kernel(); if (IS_SETLK(cmd) || IS_SETLKW(cmd)) { if (fl->fl_type != F_UNLCK) { call->a_args.block = IS_SETLKW(cmd) ? 1 : 0; status = nlmclnt_lock(call, fl); } else status = nlmclnt_unlock(call, fl); } else if (IS_GETLK(cmd)) status = nlmclnt_test(call, fl); else status = -EINVAL; fl->fl_ops->fl_release_private(fl); fl->fl_ops = NULL; unlock_kernel(); dprintk("lockd: clnt proc returns %d\n", status); return status; } EXPORT_SYMBOL_GPL(nlmclnt_proc); /* * Allocate an NLM RPC call struct * * Note: the caller must hold a reference to host. In case of failure, * this reference will be released. */ struct nlm_rqst *nlm_alloc_call(struct nlm_host *host) { struct nlm_rqst *call; for(;;) { call = kzalloc(sizeof(*call), GFP_KERNEL); if (call != NULL) { atomic_set(&call->a_count, 1); locks_init_lock(&call->a_args.lock.fl); locks_init_lock(&call->a_res.lock.fl); call->a_host = host; return call; } if (signalled()) break; printk("nlm_alloc_call: failed, waiting for memory\n"); schedule_timeout_interruptible(5*HZ); } nlm_release_host(host); return NULL; } void nlm_release_call(struct nlm_rqst *call) { if (!atomic_dec_and_test(&call->a_count)) return; nlm_release_host(call->a_host); nlmclnt_release_lockargs(call); kfree(call); } static void nlmclnt_rpc_release(void *data) { lock_kernel(); nlm_release_call(data); unlock_kernel(); } static int nlm_wait_on_grace(wait_queue_head_t *queue) { DEFINE_WAIT(wait); int status = -EINTR; prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE); if (!signalled ()) { schedule_timeout(NLMCLNT_GRACE_WAIT); try_to_freeze(); if (!signalled ()) status = 0; } finish_wait(queue, &wait); return status; } /* * Generic NLM call */ static int nlmclnt_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc) { struct nlm_host *host = req->a_host; struct rpc_clnt *clnt; struct nlm_args *argp = &req->a_args; struct nlm_res *resp = &req->a_res; struct rpc_message msg = { .rpc_argp = argp, .rpc_resp = resp, .rpc_cred = cred, }; int status; dprintk("lockd: call procedure %d on %s\n", (int)proc, host->h_name); do { if (host->h_reclaiming && !argp->reclaim) goto in_grace_period; /* If we have no RPC client yet, create one. */ if ((clnt = nlm_bind_host(host)) == NULL) return -ENOLCK; msg.rpc_proc = &clnt->cl_procinfo[proc]; /* Perform the RPC call. If an error occurs, try again */ if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) { dprintk("lockd: rpc_call returned error %d\n", -status); switch (status) { case -EPROTONOSUPPORT: status = -EINVAL; break; case -ECONNREFUSED: case -ETIMEDOUT: case -ENOTCONN: nlm_rebind_host(host); status = -EAGAIN; break; case -ERESTARTSYS: return signalled () ? -EINTR : status; default: break; } break; } else if (resp->status == nlm_lck_denied_grace_period) { dprintk("lockd: server in grace period\n"); if (argp->reclaim) { printk(KERN_WARNING "lockd: spurious grace period reject?!\n"); return -ENOLCK; } } else { if (!argp->reclaim) { /* We appear to be out of the grace period */ wake_up_all(&host->h_gracewait); } dprintk("lockd: server returns status %d\n", resp->status); return 0; /* Okay, call complete */ } in_grace_period: /* * The server has rebooted and appears to be in the grace * period during which locks are only allowed to be * reclaimed. * We can only back off and try again later. */ status = nlm_wait_on_grace(&host->h_gracewait); } while (status == 0); return status; } /* * Generic NLM call, async version. */ static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops) { struct nlm_host *host = req->a_host; struct rpc_clnt *clnt; struct rpc_task_setup task_setup_data = { .rpc_message = msg, .callback_ops = tk_ops, .callback_data = req, .flags = RPC_TASK_ASYNC, }; dprintk("lockd: call procedure %d on %s (async)\n", (int)proc, host->h_name); /* If we have no RPC client yet, create one. */ clnt = nlm_bind_host(host); if (clnt == NULL) goto out_err; msg->rpc_proc = &clnt->cl_procinfo[proc]; task_setup_data.rpc_client = clnt; /* bootstrap and kick off the async RPC call */ return rpc_run_task(&task_setup_data); out_err: tk_ops->rpc_release(req); return ERR_PTR(-ENOLCK); } static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops) { struct rpc_task *task; task = __nlm_async_call(req, proc, msg, tk_ops); if (IS_ERR(task)) return PTR_ERR(task); rpc_put_task(task); return 0; } /* * NLM asynchronous call. */ int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops) { struct rpc_message msg = { .rpc_argp = &req->a_args, .rpc_resp = &req->a_res, }; return nlm_do_async_call(req, proc, &msg, tk_ops); } int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops) { struct rpc_message msg = { .rpc_argp = &req->a_res, }; return nlm_do_async_call(req, proc, &msg, tk_ops); } /* * NLM client asynchronous call. * * Note that although the calls are asynchronous, and are therefore * guaranteed to complete, we still always attempt to wait for * completion in order to be able to correctly track the lock * state. */ static int nlmclnt_async_call(struct rpc_cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops) { struct rpc_message msg = { .rpc_argp = &req->a_args, .rpc_resp = &req->a_res, .rpc_cred = cred, }; struct rpc_task *task; int err; task = __nlm_async_call(req, proc, &msg, tk_ops); if (IS_ERR(task)) return PTR_ERR(task); err = rpc_wait_for_completion_task(task); rpc_put_task(task); return err; } /* * TEST for the presence of a conflicting lock */ static int nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl) { int status; status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST); if (status < 0) goto out; switch (req->a_res.status) { case nlm_granted: fl->fl_type = F_UNLCK; break; case nlm_lck_denied: /* * Report the conflicting lock back to the application. */ fl->fl_start = req->a_res.lock.fl.fl_start; fl->fl_end = req->a_res.lock.fl.fl_end; fl->fl_type = req->a_res.lock.fl.fl_type; fl->fl_pid = 0; break; default: status = nlm_stat_to_errno(req->a_res.status); } out: nlm_release_call(req); return status; } static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl) { new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state; new->fl_u.nfs_fl.owner = nlm_get_lockowner(fl->fl_u.nfs_fl.owner); list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted); } static void nlmclnt_locks_release_private(struct file_lock *fl) { list_del(&fl->fl_u.nfs_fl.list); nlm_put_lockowner(fl->fl_u.nfs_fl.owner); } static const struct file_lock_operations nlmclnt_lock_ops = { .fl_copy_lock = nlmclnt_locks_copy_lock, .fl_release_private = nlmclnt_locks_release_private, }; static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host) { BUG_ON(fl->fl_ops != NULL); fl->fl_u.nfs_fl.state = 0; fl->fl_u.nfs_fl.owner = nlm_find_lockowner(host, fl->fl_owner); INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list); fl->fl_ops = &nlmclnt_lock_ops; } static int do_vfs_lock(struct file_lock *fl) { int res = 0; switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) { case FL_POSIX: res = posix_lock_file_wait(fl->fl_file, fl); break; case FL_FLOCK: res = flock_lock_file_wait(fl->fl_file, fl); break; default: BUG(); } return res; } /* * LOCK: Try to create a lock * * Programmer Harassment Alert * * When given a blocking lock request in a sync RPC call, the HPUX lockd * will faithfully return LCK_BLOCKED but never cares to notify us when * the lock could be granted. This way, our local process could hang * around forever waiting for the callback. * * Solution A: Implement busy-waiting * Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES}) * * For now I am implementing solution A, because I hate the idea of * re-implementing lockd for a third time in two months. The async * calls shouldn't be too hard to do, however. * * This is one of the lovely things about standards in the NFS area: * they're so soft and squishy you can't really blame HP for doing this. */ static int nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl) { struct rpc_cred *cred = nfs_file_cred(fl->fl_file); struct nlm_host *host = req->a_host; struct nlm_res *resp = &req->a_res; struct nlm_wait *block = NULL; unsigned char fl_flags = fl->fl_flags; unsigned char fl_type; int status = -ENOLCK; if (nsm_monitor(host) < 0) goto out; req->a_args.state = nsm_local_state; fl->fl_flags |= FL_ACCESS; status = do_vfs_lock(fl); fl->fl_flags = fl_flags; if (status < 0) goto out; block = nlmclnt_prepare_block(host, fl); again: /* * Initialise resp->status to a valid non-zero value, * since 0 == nlm_lck_granted */ resp->status = nlm_lck_blocked; for(;;) { /* Reboot protection */ fl->fl_u.nfs_fl.state = host->h_state; status = nlmclnt_call(cred, req, NLMPROC_LOCK); if (status < 0) break; /* Did a reclaimer thread notify us of a server reboot? */ if (resp->status == nlm_lck_denied_grace_period) continue; if (resp->status != nlm_lck_blocked) break; /* Wait on an NLM blocking lock */ status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT); if (status < 0) break; if (resp->status != nlm_lck_blocked) break; } /* if we were interrupted while blocking, then cancel the lock request * and exit */ if (resp->status == nlm_lck_blocked) { if (!req->a_args.block) goto out_unlock; if (nlmclnt_cancel(host, req->a_args.block, fl) == 0) goto out_unblock; } if (resp->status == nlm_granted) { down_read(&host->h_rwsem); /* Check whether or not the server has rebooted */ if (fl->fl_u.nfs_fl.state != host->h_state) { up_read(&host->h_rwsem); goto again; } /* Ensure the resulting lock will get added to granted list */ fl->fl_flags |= FL_SLEEP; if (do_vfs_lock(fl) < 0) printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__); up_read(&host->h_rwsem); fl->fl_flags = fl_flags; status = 0; } if (status < 0) goto out_unlock; /* * EAGAIN doesn't make sense for sleeping locks, and in some * cases NLM_LCK_DENIED is returned for a permanent error. So * turn it into an ENOLCK. */ if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP)) status = -ENOLCK; else status = nlm_stat_to_errno(resp->status); out_unblock: nlmclnt_finish_block(block); out: nlm_release_call(req); return status; out_unlock: /* Fatal error: ensure that we remove the lock altogether */ dprintk("lockd: lock attempt ended in fatal error.\n" " Attempting to unlock.\n"); nlmclnt_finish_block(block); fl_type = fl->fl_type; fl->fl_type = F_UNLCK; down_read(&host->h_rwsem); do_vfs_lock(fl); up_read(&host->h_rwsem); fl->fl_type = fl_type; fl->fl_flags = fl_flags; nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops); return status; } /* * RECLAIM: Try to reclaim a lock */ int nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl) { struct nlm_rqst reqst, *req; int status; req = &reqst; memset(req, 0, sizeof(*req)); locks_init_lock(&req->a_args.lock.fl); locks_init_lock(&req->a_res.lock.fl); req->a_host = host; req->a_flags = 0; /* Set up the argument struct */ nlmclnt_setlockargs(req, fl); req->a_args.reclaim = 1; status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK); if (status >= 0 && req->a_res.status == nlm_granted) return 0; printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d " "(errno %d, status %d)\n", fl->fl_pid, status, ntohl(req->a_res.status)); /* * FIXME: This is a serious failure. We can * * a. Ignore the problem * b. Send the owning process some signal (Linux doesn't have * SIGLOST, though...) * c. Retry the operation * * Until someone comes up with a simple implementation * for b or c, I'll choose option a. */ return -ENOLCK; } /* * UNLOCK: remove an existing lock */ static int nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl) { struct nlm_host *host = req->a_host; struct nlm_res *resp = &req->a_res; int status; unsigned char fl_flags = fl->fl_flags; /* * Note: the server is supposed to either grant us the unlock * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either * case, we want to unlock. */ fl->fl_flags |= FL_EXISTS; down_read(&host->h_rwsem); status = do_vfs_lock(fl); up_read(&host->h_rwsem); fl->fl_flags = fl_flags; if (status == -ENOENT) { status = 0; goto out; } atomic_inc(&req->a_count); status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops); if (status < 0) goto out; if (resp->status == nlm_granted) goto out; if (resp->status != nlm_lck_denied_nolocks) printk("lockd: unexpected unlock status: %d\n", resp->status); /* What to do now? I'm out of my depth... */ status = -ENOLCK; out: nlm_release_call(req); return status; } static void nlmclnt_unlock_callback(struct rpc_task *task, void *data) { struct nlm_rqst *req = data; u32 status = ntohl(req->a_res.status); if (RPC_ASSASSINATED(task)) goto die; if (task->tk_status < 0) { dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status); goto retry_rebind; } if (status == NLM_LCK_DENIED_GRACE_PERIOD) { rpc_delay(task, NLMCLNT_GRACE_WAIT); goto retry_unlock; } if (status != NLM_LCK_GRANTED) printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status); die: return; retry_rebind: lock_kernel(); nlm_rebind_host(req->a_host); unlock_kernel(); retry_unlock: rpc_restart_call(task); } static const struct rpc_call_ops nlmclnt_unlock_ops = { .rpc_call_done = nlmclnt_unlock_callback, .rpc_release = nlmclnt_rpc_release, }; /* * Cancel a blocked lock request. * We always use an async RPC call for this in order not to hang a * process that has been Ctrl-C'ed. */ static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl) { struct nlm_rqst *req; int status; dprintk("lockd: blocking lock attempt was interrupted by a signal.\n" " Attempting to cancel lock.\n"); req = nlm_alloc_call(nlm_get_host(host)); if (!req) return -ENOMEM; req->a_flags = RPC_TASK_ASYNC; nlmclnt_setlockargs(req, fl); req->a_args.block = block; atomic_inc(&req->a_count); status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req, NLMPROC_CANCEL, &nlmclnt_cancel_ops); if (status == 0 && req->a_res.status == nlm_lck_denied) status = -ENOLCK; nlm_release_call(req); return status; } static void nlmclnt_cancel_callback(struct rpc_task *task, void *data) { struct nlm_rqst *req = data; u32 status = ntohl(req->a_res.status); if (RPC_ASSASSINATED(task)) goto die; if (task->tk_status < 0) { dprintk("lockd: CANCEL call error %d, retrying.\n", task->tk_status); goto retry_cancel; } dprintk("lockd: cancel status %u (task %u)\n", status, task->tk_pid); switch (status) { case NLM_LCK_GRANTED: case NLM_LCK_DENIED_GRACE_PERIOD: case NLM_LCK_DENIED: /* Everything's good */ break; case NLM_LCK_DENIED_NOLOCKS: dprintk("lockd: CANCEL failed (server has no locks)\n"); goto retry_cancel; default: printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n", status); } die: return; retry_cancel: /* Don't ever retry more than 3 times */ if (req->a_retries++ >= NLMCLNT_MAX_RETRIES) goto die; lock_kernel(); nlm_rebind_host(req->a_host); unlock_kernel(); rpc_restart_call(task); rpc_delay(task, 30 * HZ); } static const struct rpc_call_ops nlmclnt_cancel_ops = { .rpc_call_done = nlmclnt_cancel_callback, .rpc_release = nlmclnt_rpc_release, }; /* * Convert an NLM status code to a generic kernel errno */ static int nlm_stat_to_errno(__be32 status) { switch(ntohl(status)) { case NLM_LCK_GRANTED: return 0; case NLM_LCK_DENIED: return -EAGAIN; case NLM_LCK_DENIED_NOLOCKS: case NLM_LCK_DENIED_GRACE_PERIOD: return -ENOLCK; case NLM_LCK_BLOCKED: printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n"); return -ENOLCK; #ifdef CONFIG_LOCKD_V4 case NLM_DEADLCK: return -EDEADLK; case NLM_ROFS: return -EROFS; case NLM_STALE_FH: return -ESTALE; case NLM_FBIG: return -EOVERFLOW; case NLM_FAILED: return -ENOLCK; #endif } printk(KERN_NOTICE "lockd: unexpected server status %d\n", status); return -ENOLCK; }