/*
 * linux/fs/lockd/clntproc.c
 *
 * RPC procedures for the client side NLM implementation
 *
 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/config.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/nfs_fs.h>
#include <linux/utsname.h>
#include <linux/smp_lock.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/lockd/lockd.h>
#include <linux/lockd/sm_inter.h>

#define NLMDBG_FACILITY         NLMDBG_CLIENT
#define NLMCLNT_GRACE_WAIT      (5*HZ)

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 void     nlmclnt_unlock_callback(struct rpc_task *);
static void     nlmclnt_cancel_callback(struct rpc_task *);
static int      nlm_stat_to_errno(u32 stat);

/*
 * Cookie counter for NLM requests
 */
static u32      nlm_cookie = 0x1234;

static inline void nlmclnt_next_cookie(struct nlm_cookie *c)
{
        memcpy(c->data, &nlm_cookie, 4);
        memset(c->data+4, 0, 4);
        c->len=4;
        nlm_cookie++;
}

/*
 * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
 */
static inline 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);
        argp->state   = nsm_local_state;
        memcpy(&lock->fh, NFS_FH(fl->fl_file->f_dentry->d_inode), sizeof(struct nfs_fh));
        lock->caller  = system_utsname.nodename;
        lock->oh.data = req->a_owner;
        lock->oh.len  = sprintf(req->a_owner, "%d@%s",
                                current->pid, system_utsname.nodename);
        locks_copy_lock(&lock->fl, fl);
}

/*
 * Initialize arguments for GRANTED call. The nlm_rqst structure
 * has been cleared already.
 */
int
nlmclnt_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
{
        locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
        memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
        call->a_args.lock.caller = system_utsname.nodename;
        call->a_args.lock.oh.len = lock->oh.len;

        /* set default data area */
        call->a_args.lock.oh.data = call->a_owner;

        if (lock->oh.len > NLMCLNT_OHSIZE) {
                void *data = kmalloc(lock->oh.len, GFP_KERNEL);
                if (!data)
                        return 0;
                call->a_args.lock.oh.data = (u8 *) data;
        }

        memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
        return 1;
}

void
nlmclnt_freegrantargs(struct nlm_rqst *call)
{
        /*
         * Check whether we allocated memory for the owner.
         */
        if (call->a_args.lock.oh.data != (u8 *) call->a_owner) {
                kfree(call->a_args.lock.oh.data);
        }
}

/*
 * This is the main entry point for the NLM client.
 */
int
nlmclnt_proc(struct inode *inode, int cmd, struct file_lock *fl)
{
        struct nfs_server       *nfssrv = NFS_SERVER(inode);
        struct nlm_host         *host;
        struct nlm_rqst         reqst, *call = &reqst;
        sigset_t                oldset;
        unsigned long           flags;
        int                     status, proto, vers;

        vers = (NFS_PROTO(inode)->version == 3) ? 4 : 1;
        if (NFS_PROTO(inode)->version > 3) {
                printk(KERN_NOTICE "NFSv4 file locking not implemented!\n");
                return -ENOLCK;
        }

        /* Retrieve transport protocol from NFS client */
        proto = NFS_CLIENT(inode)->cl_xprt->prot;

        if (!(host = nlmclnt_lookup_host(NFS_ADDR(inode), proto, vers)))
                return -ENOLCK;

        /* Create RPC client handle if not there, and copy soft
         * and intr flags from NFS client. */
        if (host->h_rpcclnt == NULL) {
                struct rpc_clnt *clnt;

                /* Bind an rpc client to this host handle (does not
                 * perform a portmapper lookup) */
                if (!(clnt = nlm_bind_host(host))) {
                        status = -ENOLCK;
                        goto done;
                }
                clnt->cl_softrtry = nfssrv->client->cl_softrtry;
                clnt->cl_intr     = nfssrv->client->cl_intr;
                clnt->cl_chatty   = nfssrv->client->cl_chatty;
        }

        /* Keep the old signal mask */
        spin_lock_irqsave(&current->sigmask_lock, flags);
        oldset = current->blocked;

        /* If we're cleaning up locks because the process is exiting,
         * perform the RPC call asynchronously. */
        if ((IS_SETLK(cmd) || IS_SETLKW(cmd))
            && fl->fl_type == F_UNLCK
            && (current->flags & PF_EXITING)) {
                sigfillset(&current->blocked);  /* Mask all signals */
                recalc_sigpending(current);
                spin_unlock_irqrestore(&current->sigmask_lock, flags);

                call = nlmclnt_alloc_call();
                if (!call) {
                        status = -ENOMEM;
                        goto out_restore;
                }
                call->a_flags = RPC_TASK_ASYNC;
        } else {
                spin_unlock_irqrestore(&current->sigmask_lock, flags);
                memset(call, 0, sizeof(*call));
                locks_init_lock(&call->a_args.lock.fl);
                locks_init_lock(&call->a_res.lock.fl);
        }
        call->a_host = host;

        /* Set up the argument struct */
        nlmclnt_setlockargs(call, fl);

        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;

        if (status < 0 && (call->a_flags & RPC_TASK_ASYNC))
                kfree(call);

 out_restore:
        spin_lock_irqsave(&current->sigmask_lock, flags);
        current->blocked = oldset;
        recalc_sigpending(current);
        spin_unlock_irqrestore(&current->sigmask_lock, flags);

done:
        dprintk("lockd: clnt proc returns %d\n", status);
        nlm_release_host(host);
        return status;
}

/*
 * Wait while server is in grace period
 */
static inline int
nlmclnt_grace_wait(struct nlm_host *host)
{
        if (!host->h_reclaiming)
                interruptible_sleep_on_timeout(&host->h_gracewait, 10*HZ);
        else
                interruptible_sleep_on(&host->h_gracewait);
        return signalled()? -ERESTARTSYS : 0;
}

/*
 * Allocate an NLM RPC call struct
 */
struct nlm_rqst *
nlmclnt_alloc_call(void)
{
        struct nlm_rqst *call;

        while (!signalled()) {
                call = (struct nlm_rqst *) kmalloc(sizeof(struct nlm_rqst), GFP_KERNEL);
                if (call) {
                        memset(call, 0, sizeof(*call));
                        locks_init_lock(&call->a_args.lock.fl);
                        locks_init_lock(&call->a_res.lock.fl);
                        return call;
                }
                printk("nlmclnt_alloc_call: failed, waiting for memory\n");
                current->state = TASK_INTERRUPTIBLE;
                schedule_timeout(5*HZ);
        }
        return NULL;
}

/*
 * Generic NLM call
 */
int
nlmclnt_call(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 file     *filp = argp->lock.fl.fl_file;
        struct rpc_message msg;
        int             status;

        dprintk("lockd: call procedure %s on %s\n",
                        nlm_procname(proc), host->h_name);

        msg.rpc_proc = proc;
        msg.rpc_argp = argp;
        msg.rpc_resp = resp;
        if (filp)
                msg.rpc_cred = nfs_file_cred(filp);
        else
                msg.rpc_cred = NULL;

        do {
                if (host->h_reclaiming && !argp->reclaim) {
                        interruptible_sleep_on(&host->h_gracewait);
                        continue;
                }

                /* If we have no RPC client yet, create one. */
                if ((clnt = nlm_bind_host(host)) == NULL)
                        return -ENOLCK;

                /* 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 {
                        dprintk("lockd: server returns status %d\n", resp->status);
                        return 0;       /* Okay, call complete */
                }

                /* Back off a little and try again */
                interruptible_sleep_on_timeout(&host->h_gracewait, 15*HZ);

                /* When the lock requested by F_SETLKW isn't available,
                   we will wait until the request can be satisfied. If
                   a signal is received during wait, we should return
                   -EINTR. */
                if (signalled ()) {
                        status = -EINTR;
                        break;
                }
        } while (1);

        return status;
}

/*
 * Generic NLM call, async version.
 */
int
nlmsvc_async_call(struct nlm_rqst *req, u32 proc, rpc_action callback)
{
        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;
        int             status;

        dprintk("lockd: call procedure %s on %s (async)\n",
                        nlm_procname(proc), host->h_name);

        /* If we have no RPC client yet, create one. */
        if ((clnt = nlm_bind_host(host)) == NULL)
                return -ENOLCK;

        /* bootstrap and kick off the async RPC call */
        msg.rpc_proc = proc;
        msg.rpc_argp = argp;
        msg.rpc_resp =resp;
        msg.rpc_cred = NULL;    
        status = rpc_call_async(clnt, &msg, RPC_TASK_ASYNC, callback, req);

        return status;
}

int
nlmclnt_async_call(struct nlm_rqst *req, u32 proc, rpc_action callback)
{
        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 file     *file = argp->lock.fl.fl_file;
        struct rpc_message msg;
        int             status;

        dprintk("lockd: call procedure %s on %s (async)\n",
                        nlm_procname(proc), host->h_name);

        /* If we have no RPC client yet, create one. */
        if ((clnt = nlm_bind_host(host)) == NULL)
                return -ENOLCK;

        /* bootstrap and kick off the async RPC call */
        msg.rpc_proc = proc;
        msg.rpc_argp = argp;
        msg.rpc_resp =resp;
        if (file)
                msg.rpc_cred = nfs_file_cred(file);
        else
                msg.rpc_cred = NULL;
        /* Increment host refcount */
        nlm_get_host(host);
        status = rpc_call_async(clnt, &msg, RPC_TASK_ASYNC, callback, req);
        if (status < 0)
                nlm_release_host(host);
        return status;
}

/*
 * TEST for the presence of a conflicting lock
 */
static int
nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
{
        int     status;

        if ((status = nlmclnt_call(req, NLMPROC_TEST)) < 0)
                return status;

        status = req->a_res.status;
        if (status == NLM_LCK_GRANTED) {
                fl->fl_type = F_UNLCK;
        } if (status == NLM_LCK_DENIED) {
                /*
                 * Report the conflicting lock back to the application.
                 * FIXME: Is it OK to report the pid back as well?
                 */
                locks_copy_lock(fl, &req->a_res.lock.fl);
                /* fl->fl_pid = 0; */
        } else {
                return nlm_stat_to_errno(req->a_res.status);
        }

        return 0;
}

static
void nlmclnt_insert_lock_callback(struct file_lock *fl)
{
        nlm_get_host(fl->fl_u.nfs_fl.host);
}
static
void nlmclnt_remove_lock_callback(struct file_lock *fl)
{
        if (fl->fl_u.nfs_fl.host) {
                nlm_release_host(fl->fl_u.nfs_fl.host);
                fl->fl_u.nfs_fl.host = NULL;
        }
}

/*
 * 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 nlm_host *host = req->a_host;
        struct nlm_res  *resp = &req->a_res;
        int             status;

        if (!host->h_monitored && nsm_monitor(host) < 0) {
                printk(KERN_NOTICE "lockd: failed to monitor %s\n",
                                        host->h_name);
                return -ENOLCK;
        }

        do {
                if ((status = nlmclnt_call(req, NLMPROC_LOCK)) >= 0) {
                        if (resp->status != NLM_LCK_BLOCKED)
                                break;
                        status = nlmclnt_block(host, fl, &resp->status);
                }
                if (status < 0)
                        return status;
        } while (resp->status == NLM_LCK_BLOCKED && req->a_args.block);

        if (resp->status == NLM_LCK_GRANTED) {
                fl->fl_u.nfs_fl.state = host->h_state;
                fl->fl_u.nfs_fl.flags |= NFS_LCK_GRANTED;
                fl->fl_u.nfs_fl.host = host;
                fl->fl_insert = nlmclnt_insert_lock_callback;
                fl->fl_remove = nlmclnt_remove_lock_callback;
        }

        return nlm_stat_to_errno(resp->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;

        if ((status = nlmclnt_call(req, NLMPROC_LOCK)) >= 0
         && req->a_res.status == NLM_LCK_GRANTED)
                return 0;

        printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
                                "(errno %d, status %d)\n", fl->fl_pid,
                                status, 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_res  *resp = &req->a_res;
        int             status;

        /* Clean the GRANTED flag now so the lock doesn't get
         * reclaimed while we're stuck in the unlock call. */
        fl->fl_u.nfs_fl.flags &= ~NFS_LCK_GRANTED;

        if (req->a_flags & RPC_TASK_ASYNC) {
                return nlmclnt_async_call(req, NLMPROC_UNLOCK,
                                        nlmclnt_unlock_callback);
        }

        if ((status = nlmclnt_call(req, NLMPROC_UNLOCK)) < 0)
                return status;

        if (resp->status == NLM_LCK_GRANTED)
                return 0;

        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... */

        return -ENOLCK;
}

static void
nlmclnt_unlock_callback(struct rpc_task *task)
{
        struct nlm_rqst *req = (struct nlm_rqst *) task->tk_calldata;
        int             status = 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:
        nlm_release_host(req->a_host);
        kfree(req);
        return;
 retry_rebind:
        nlm_rebind_host(req->a_host);
 retry_unlock:
        rpc_restart_call(task);
}

/*
 * 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.
 */
int
nlmclnt_cancel(struct nlm_host *host, struct file_lock *fl)
{
        struct nlm_rqst *req;
        unsigned long   flags;
        sigset_t        oldset;
        int             status;

        /* Block all signals while setting up call */
        spin_lock_irqsave(&current->sigmask_lock, flags);
        oldset = current->blocked;
        sigfillset(&current->blocked);
        recalc_sigpending(current);
        spin_unlock_irqrestore(&current->sigmask_lock, flags);

        req = nlmclnt_alloc_call();
        if (!req)
                return -ENOMEM;
        req->a_host  = host;
        req->a_flags = RPC_TASK_ASYNC;

        nlmclnt_setlockargs(req, fl);

        status = nlmclnt_async_call(req, NLMPROC_CANCEL,
                                        nlmclnt_cancel_callback);
        if (status < 0)
                kfree(req);

        spin_lock_irqsave(&current->sigmask_lock, flags);
        current->blocked = oldset;
        recalc_sigpending(current);
        spin_unlock_irqrestore(&current->sigmask_lock, flags);

        return status;
}

static void
nlmclnt_cancel_callback(struct rpc_task *task)
{
        struct nlm_rqst *req = (struct nlm_rqst *) task->tk_calldata;

        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 %d (task %d)\n",
                        req->a_res.status, task->tk_pid);

        switch (req->a_res.status) {
        case NLM_LCK_GRANTED:
        case NLM_LCK_DENIED_GRACE_PERIOD:
                /* 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",
                        req->a_res.status);
        }

die:
        nlm_release_host(req->a_host);
        kfree(req);
        return;

retry_cancel:
        nlm_rebind_host(req->a_host);
        rpc_restart_call(task);
        rpc_delay(task, 30 * HZ);
}

/*
 * Convert an NLM status code to a generic kernel errno
 */
static int
nlm_stat_to_errno(u32 status)
{
        switch(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;
}