/*
 * linux/fs/nfsd/nfssvc.c
 *
 * Central processing for nfsd.
 *
 * Authors:     Olaf Kirch (okir@monad.swb.de)
 *
 * Copyright (C) 1995, 1996, 1997 Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/config.h>
#include <linux/module.h>

#include <linux/time.h>
#include <linux/errno.h>
#include <linux/nfs.h>
#include <linux/in.h>
#include <linux/uio.h>
#include <linux/unistd.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/fs_struct.h>

#include <linux/sunrpc/types.h>
#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/sunrpc/cache.h>
#include <linux/nfsd/nfsd.h>
#include <linux/nfsd/stats.h>
#include <linux/nfsd/cache.h>
#include <linux/lockd/bind.h>

#define NFSDDBG_FACILITY        NFSDDBG_SVC

/* these signals will be delivered to an nfsd thread 
 * when handling a request
 */
#define ALLOWED_SIGS    (sigmask(SIGKILL))
/* these signals will be delivered to an nfsd thread
 * when not handling a request. i.e. when waiting
 */
#define SHUTDOWN_SIGS   (sigmask(SIGKILL) | sigmask(SIGHUP) | sigmask(SIGINT) | sigmask(SIGQUIT))
/* if the last thread dies with SIGHUP, then the exports table is
 * left unchanged ( like 2.4-{0-9} ).  Any other signal will clear
 * the exports table (like 2.2).
 */
#define SIG_NOCLEAN     SIGHUP

extern struct svc_program       nfsd_program;
static void                     nfsd(struct svc_rqst *rqstp);
struct timeval                  nfssvc_boot;
static struct svc_serv          *nfsd_serv;
static atomic_t                 nfsd_busy;
static unsigned long            nfsd_last_call;
static spinlock_t               nfsd_call_lock = SPIN_LOCK_UNLOCKED;

struct nfsd_list {
        struct list_head        list;
        struct task_struct      *task;
};
struct list_head nfsd_list = LIST_HEAD_INIT(nfsd_list);

/*
 * Maximum number of nfsd processes
 */
#define NFSD_MAXSERVS           8192

int nfsd_nrthreads(void)
{
        if (nfsd_serv == NULL)
                return 0;
        else
                return nfsd_serv->sv_nrthreads;
}

int
nfsd_svc(unsigned short port, int nrservs)
{
        int     error;
        int     none_left;      
        struct list_head *victim;
        
        lock_kernel();
        dprintk("nfsd: creating service\n");
        error = -EINVAL;
        if (nrservs <= 0)
                nrservs = 0;
        if (nrservs > NFSD_MAXSERVS)
                nrservs = NFSD_MAXSERVS;
        
        /* Readahead param cache - will no-op if it already exists */
        error = nfsd_racache_init(2*nrservs);
        nfs4_state_init();
        if (error<0)
                goto out;
        if (!nfsd_serv) {
                atomic_set(&nfsd_busy, 0);
                error = -ENOMEM;
                nfsd_serv = svc_create(&nfsd_program, NFSD_BUFSIZE);
                if (nfsd_serv == NULL)
                        goto out;
                error = svc_makesock(nfsd_serv, IPPROTO_UDP, port);
                if (error < 0)
                        goto failure;

#ifdef CONFIG_NFSD_TCP
                error = svc_makesock(nfsd_serv, IPPROTO_TCP, port);
                if (error < 0)
                        goto failure;
#endif
                do_gettimeofday(&nfssvc_boot);          /* record boot time */
        } else
                nfsd_serv->sv_nrthreads++;
        nrservs -= (nfsd_serv->sv_nrthreads-1);
        while (nrservs > 0) {
                nrservs--;
                __module_get(THIS_MODULE);
                error = svc_create_thread(nfsd, nfsd_serv);
                if (error < 0) {
                        module_put(THIS_MODULE);
                        break;
                }
        }
        victim = nfsd_list.next;
        while (nrservs < 0 && victim != &nfsd_list) {
                struct nfsd_list *nl =
                        list_entry(victim,struct nfsd_list, list);
                victim = victim->next;
                send_sig(SIG_NOCLEAN, nl->task, 1);
                nrservs++;
        }
 failure:
        none_left = (nfsd_serv->sv_nrthreads == 1);
        svc_destroy(nfsd_serv);         /* Release server */
        if (none_left) {
                nfsd_serv = NULL;
                nfsd_racache_shutdown();
                nfs4_state_shutdown();
        }
 out:
        unlock_kernel();
        return error;
}

static inline void
update_thread_usage(int busy_threads)
{
        unsigned long prev_call;
        unsigned long diff;
        int decile;

        spin_lock(&nfsd_call_lock);
        prev_call = nfsd_last_call;
        nfsd_last_call = jiffies;
        decile = busy_threads*10/nfsdstats.th_cnt;
        if (decile>0 && decile <= 10) {
                diff = nfsd_last_call - prev_call;
                if ( (nfsdstats.th_usage[decile-1] += diff) >= NFSD_USAGE_WRAP)
                        nfsdstats.th_usage[decile-1] -= NFSD_USAGE_WRAP;
                if (decile == 10)
                        nfsdstats.th_fullcnt++;
        }
        spin_unlock(&nfsd_call_lock);
}

/*
 * This is the NFS server kernel thread
 */
static void
nfsd(struct svc_rqst *rqstp)
{
        struct svc_serv *serv = rqstp->rq_server;
        struct fs_struct *fsp;
        int             err;
        struct nfsd_list me;
        sigset_t shutdown_mask, allowed_mask;

        /* Lock module and set up kernel thread */
        lock_kernel();
        daemonize("nfsd");

        /* After daemonize() this kernel thread shares current->fs
         * with the init process. We need to create files with a
         * umask of 0 instead of init's umask. */
        fsp = copy_fs_struct(current->fs);
        if (!fsp) {
                printk("Unable to start nfsd thread: out of memory\n");
                goto out;
        }
        exit_fs(current);
        current->fs = fsp;
        current->fs->umask = 0;

        siginitsetinv(&shutdown_mask, SHUTDOWN_SIGS);
        siginitsetinv(&allowed_mask, ALLOWED_SIGS);

        nfsdstats.th_cnt++;

        lockd_up();                             /* start lockd */

        me.task = current;
        list_add(&me.list, &nfsd_list);

        unlock_kernel();

        /*
         * We want less throttling in balance_dirty_pages() so that nfs to
         * localhost doesn't cause nfsd to lock up due to all the client's
         * dirty pages.
         */
        current->flags |= PF_LESS_THROTTLE;

        /*
         * The main request loop
         */
        for (;;) {
                /* Block all but the shutdown signals */
                sigprocmask(SIG_SETMASK, &shutdown_mask, NULL);

                /*
                 * Find a socket with data available and call its
                 * recvfrom routine.
                 */
                while ((err = svc_recv(serv, rqstp,
                                       60*60*HZ)) == -EAGAIN)
                        ;
                if (err < 0)
                        break;
                update_thread_usage(atomic_read(&nfsd_busy));
                atomic_inc(&nfsd_busy);

                /* Lock the export hash tables for reading. */
                exp_readlock();

                /* Process request with signals blocked.  */
                sigprocmask(SIG_SETMASK, &allowed_mask, NULL);

                svc_process(serv, rqstp);

                /* Unlock export hash tables */
                exp_readunlock();
                update_thread_usage(atomic_read(&nfsd_busy));
                atomic_dec(&nfsd_busy);
        }

        if (err != -EINTR) {
                printk(KERN_WARNING "nfsd: terminating on error %d\n", -err);
        } else {
                unsigned int    signo;

                for (signo = 1; signo <= _NSIG; signo++)
                        if (sigismember(&current->pending.signal, signo) &&
                            !sigismember(&current->blocked, signo))
                                break;
                err = signo;
        }

        lock_kernel();

        /* Release lockd */
        lockd_down();

        /* Check if this is last thread */
        if (serv->sv_nrthreads==1) {
                
                printk(KERN_WARNING "nfsd: last server has exited\n");
                if (err != SIG_NOCLEAN) {
                        printk(KERN_WARNING "nfsd: unexporting all filesystems\n");
                        nfsd_export_flush();
                }
                nfsd_serv = NULL;
                nfsd_racache_shutdown();        /* release read-ahead cache */
                nfs4_state_shutdown();
        }
        list_del(&me.list);
        nfsdstats.th_cnt --;

out:
        /* Release the thread */
        svc_exit_thread(rqstp);

        /* Release module */
        module_put_and_exit(0);
}

int
nfsd_dispatch(struct svc_rqst *rqstp, u32 *statp)
{
        struct svc_procedure    *proc;
        kxdrproc_t              xdr;
        u32                     nfserr;
        u32                     *nfserrp;

        dprintk("nfsd_dispatch: vers %d proc %d\n",
                                rqstp->rq_vers, rqstp->rq_proc);
        proc = rqstp->rq_procinfo;

        /* Check whether we have this call in the cache. */
        switch (nfsd_cache_lookup(rqstp, proc->pc_cachetype)) {
        case RC_INTR:
        case RC_DROPIT:
                return 0;
        case RC_REPLY:
                return 1;
        case RC_DOIT:;
                /* do it */
        }

        /* Decode arguments */
        xdr = proc->pc_decode;
        if (xdr && !xdr(rqstp, (u32*)rqstp->rq_arg.head[0].iov_base,
                        rqstp->rq_argp)) {
                dprintk("nfsd: failed to decode arguments!\n");
                nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
                *statp = rpc_garbage_args;
                return 1;
        }

        /* need to grab the location to store the status, as
         * nfsv4 does some encoding while processing 
         */
        nfserrp = rqstp->rq_res.head[0].iov_base
                + rqstp->rq_res.head[0].iov_len;
        rqstp->rq_res.head[0].iov_len += sizeof(u32);

        /* Now call the procedure handler, and encode NFS status. */
        nfserr = proc->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
        if (nfserr == nfserr_jukebox && rqstp->rq_vers == 2)
                nfserr = nfserr_dropit;
        if (nfserr == nfserr_dropit) {
                dprintk("nfsd: Dropping request due to malloc failure!\n");
                nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
                return 0;
        }

        if (rqstp->rq_proc != 0)
                *nfserrp++ = nfserr;

        /* Encode result.
         * For NFSv2, additional info is never returned in case of an error.
         */
        if (!(nfserr && rqstp->rq_vers == 2)) {
                xdr = proc->pc_encode;
                if (xdr && !xdr(rqstp, nfserrp,
                                rqstp->rq_resp)) {
                        /* Failed to encode result. Release cache entry */
                        dprintk("nfsd: failed to encode result!\n");
                        nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
                        *statp = rpc_system_err;
                        return 1;
                }
        }

        /* Store reply in cache. */
        nfsd_cache_update(rqstp, proc->pc_cachetype, statp + 1);
        return 1;
}

extern struct svc_version nfsd_version2, nfsd_version3, nfsd_version4;

static struct svc_version *     nfsd_version[] = {
        [2] = &nfsd_version2,
#if defined(CONFIG_NFSD_V3)
        [3] = &nfsd_version3,
#endif
#if defined(CONFIG_NFSD_V4)
        [4] = &nfsd_version4,
#endif
};

#define NFSD_NRVERS             (sizeof(nfsd_version)/sizeof(nfsd_version[0]))
struct svc_program              nfsd_program = {
        .pg_prog                = NFS_PROGRAM,          /* program number */
        .pg_nvers               = NFSD_NRVERS,          /* nr of entries in nfsd_version */
        .pg_vers                = nfsd_version,         /* version table */
        .pg_name                = "nfsd",               /* program name */
        .pg_class               = "nfsd",               /* authentication class */
        .pg_stats               = &nfsd_svcstats,       /* version table */
};