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

#include <linux/sched.h>
#include <linux/freezer.h>
#include <linux/fs_struct.h>
#include <linux/swap.h>

#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/lockd/bind.h>
#include <linux/nfsacl.h>
#include <linux/seq_file.h>
#include <net/net_namespace.h>
#include "nfsd.h"
#include "cache.h"
#include "vfs.h"

#define NFSDDBG_FACILITY        NFSDDBG_SVC

extern struct svc_program       nfsd_program;
static int                      nfsd(void *vrqstp);
struct timeval                  nfssvc_boot;

/*
 * nfsd_mutex protects nfsd_serv -- both the pointer itself and the members
 * of the svc_serv struct. In particular, ->sv_nrthreads but also to some
 * extent ->sv_temp_socks and ->sv_permsocks. It also protects nfsdstats.th_cnt
 *
 * If (out side the lock) nfsd_serv is non-NULL, then it must point to a
 * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0. That number
 * of nfsd threads must exist and each must listed in ->sp_all_threads in each
 * entry of ->sv_pools[].
 *
 * Transitions of the thread count between zero and non-zero are of particular
 * interest since the svc_serv needs to be created and initialized at that
 * point, or freed.
 *
 * Finally, the nfsd_mutex also protects some of the global variables that are
 * accessed when nfsd starts and that are settable via the write_* routines in
 * nfsctl.c. In particular:
 *
 *      user_recovery_dirname
 *      user_lease_time
 *      nfsd_versions
 */
DEFINE_MUTEX(nfsd_mutex);
struct svc_serv                 *nfsd_serv;

/*
 * nfsd_drc_lock protects nfsd_drc_max_pages and nfsd_drc_pages_used.
 * nfsd_drc_max_pages limits the total amount of memory available for
 * version 4.1 DRC caches.
 * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage.
 */
spinlock_t      nfsd_drc_lock;
unsigned int    nfsd_drc_max_mem;
unsigned int    nfsd_drc_mem_used;

#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
static struct svc_stat  nfsd_acl_svcstats;
static struct svc_version *     nfsd_acl_version[] = {
        [2] = &nfsd_acl_version2,
        [3] = &nfsd_acl_version3,
};

#define NFSD_ACL_MINVERS            2
#define NFSD_ACL_NRVERS         ARRAY_SIZE(nfsd_acl_version)
static struct svc_version *nfsd_acl_versions[NFSD_ACL_NRVERS];

static struct svc_program       nfsd_acl_program = {
        .pg_prog                = NFS_ACL_PROGRAM,
        .pg_nvers               = NFSD_ACL_NRVERS,
        .pg_vers                = nfsd_acl_versions,
        .pg_name                = "nfsacl",
        .pg_class               = "nfsd",
        .pg_stats               = &nfsd_acl_svcstats,
        .pg_authenticate        = &svc_set_client,
};

static struct svc_stat  nfsd_acl_svcstats = {
        .program        = &nfsd_acl_program,
};
#endif /* defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) */

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_MINVERS            2
#define NFSD_NRVERS             ARRAY_SIZE(nfsd_version)
static struct svc_version *nfsd_versions[NFSD_NRVERS];

struct svc_program              nfsd_program = {
#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
        .pg_next                = &nfsd_acl_program,
#endif
        .pg_prog                = NFS_PROGRAM,          /* program number */
        .pg_nvers               = NFSD_NRVERS,          /* nr of entries in nfsd_version */
        .pg_vers                = nfsd_versions,        /* version table */
        .pg_name                = "nfsd",               /* program name */
        .pg_class               = "nfsd",               /* authentication class */
        .pg_stats               = &nfsd_svcstats,       /* version table */
        .pg_authenticate        = &svc_set_client,      /* export authentication */

};

u32 nfsd_supported_minorversion;

int nfsd_vers(int vers, enum vers_op change)
{
        if (vers < NFSD_MINVERS || vers >= NFSD_NRVERS)
                return 0;
        switch(change) {
        case NFSD_SET:
                nfsd_versions[vers] = nfsd_version[vers];
#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
                if (vers < NFSD_ACL_NRVERS)
                        nfsd_acl_versions[vers] = nfsd_acl_version[vers];
#endif
                break;
        case NFSD_CLEAR:
                nfsd_versions[vers] = NULL;
#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
                if (vers < NFSD_ACL_NRVERS)
                        nfsd_acl_versions[vers] = NULL;
#endif
                break;
        case NFSD_TEST:
                return nfsd_versions[vers] != NULL;
        case NFSD_AVAIL:
                return nfsd_version[vers] != NULL;
        }
        return 0;
}

int nfsd_minorversion(u32 minorversion, enum vers_op change)
{
        if (minorversion > NFSD_SUPPORTED_MINOR_VERSION)
                return -1;
        switch(change) {
        case NFSD_SET:
                nfsd_supported_minorversion = minorversion;
                break;
        case NFSD_CLEAR:
                if (minorversion == 0)
                        return -1;
                nfsd_supported_minorversion = minorversion - 1;
                break;
        case NFSD_TEST:
                return minorversion <= nfsd_supported_minorversion;
        case NFSD_AVAIL:
                return minorversion <= NFSD_SUPPORTED_MINOR_VERSION;
        }
        return 0;
}

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

int nfsd_nrthreads(void)
{
        int rv = 0;
        mutex_lock(&nfsd_mutex);
        if (nfsd_serv)
                rv = nfsd_serv->sv_nrthreads;
        mutex_unlock(&nfsd_mutex);
        return rv;
}

static int nfsd_init_socks(int port)
{
        int error;
        if (!list_empty(&nfsd_serv->sv_permsocks))
                return 0;

        error = svc_create_xprt(nfsd_serv, "udp", &init_net, PF_INET, port,
                                        SVC_SOCK_DEFAULTS);
        if (error < 0)
                return error;

        error = svc_create_xprt(nfsd_serv, "tcp", &init_net, PF_INET, port,
                                        SVC_SOCK_DEFAULTS);
        if (error < 0)
                return error;

        return 0;
}

static bool nfsd_up = false;

static int nfsd_startup(unsigned short port, int nrservs)
{
        int ret;

        if (nfsd_up)
                return 0;
        /*
         * Readahead param cache - will no-op if it already exists.
         * (Note therefore results will be suboptimal if number of
         * threads is modified after nfsd start.)
         */
        ret = nfsd_racache_init(2*nrservs);
        if (ret)
                return ret;
        ret = nfsd_init_socks(port);
        if (ret)
                goto out_racache;
        ret = lockd_up();
        if (ret)
                goto out_racache;
        ret = nfs4_state_start();
        if (ret)
                goto out_lockd;
        nfsd_up = true;
        return 0;
out_lockd:
        lockd_down();
out_racache:
        nfsd_racache_shutdown();
        return ret;
}

static void nfsd_shutdown(void)
{
        /*
         * write_ports can create the server without actually starting
         * any threads--if we get shut down before any threads are
         * started, then nfsd_last_thread will be run before any of this
         * other initialization has been done.
         */
        if (!nfsd_up)
                return;
        nfs4_state_shutdown();
        lockd_down();
        nfsd_racache_shutdown();
        nfsd_up = false;
}

static void nfsd_last_thread(struct svc_serv *serv)
{
        /* When last nfsd thread exits we need to do some clean-up */
        nfsd_serv = NULL;
        nfsd_shutdown();

        printk(KERN_WARNING "nfsd: last server has exited, flushing export "
                            "cache\n");
        nfsd_export_flush();
}

void nfsd_reset_versions(void)
{
        int found_one = 0;
        int i;

        for (i = NFSD_MINVERS; i < NFSD_NRVERS; i++) {
                if (nfsd_program.pg_vers[i])
                        found_one = 1;
        }

        if (!found_one) {
                for (i = NFSD_MINVERS; i < NFSD_NRVERS; i++)
                        nfsd_program.pg_vers[i] = nfsd_version[i];
#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
                for (i = NFSD_ACL_MINVERS; i < NFSD_ACL_NRVERS; i++)
                        nfsd_acl_program.pg_vers[i] =
                                nfsd_acl_version[i];
#endif
        }
}

/*
 * Each session guarantees a negotiated per slot memory cache for replies
 * which in turn consumes memory beyond the v2/v3/v4.0 server. A dedicated
 * NFSv4.1 server might want to use more memory for a DRC than a machine
 * with mutiple services.
 *
 * Impose a hard limit on the number of pages for the DRC which varies
 * according to the machines free pages. This is of course only a default.
 *
 * For now this is a #defined shift which could be under admin control
 * in the future.
 */
static void set_max_drc(void)
{
        #define NFSD_DRC_SIZE_SHIFT     10
        nfsd_drc_max_mem = (nr_free_buffer_pages()
                                        >> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE;
        nfsd_drc_mem_used = 0;
        spin_lock_init(&nfsd_drc_lock);
        dprintk("%s nfsd_drc_max_mem %u \n", __func__, nfsd_drc_max_mem);
}

int nfsd_create_serv(void)
{
        int err = 0;

        WARN_ON(!mutex_is_locked(&nfsd_mutex));
        if (nfsd_serv) {
                svc_get(nfsd_serv);
                return 0;
        }
        if (nfsd_max_blksize == 0) {
                /* choose a suitable default */
                struct sysinfo i;
                si_meminfo(&i);
                /* Aim for 1/4096 of memory per thread
                 * This gives 1MB on 4Gig machines
                 * But only uses 32K on 128M machines.
                 * Bottom out at 8K on 32M and smaller.
                 * Of course, this is only a default.
                 */
                nfsd_max_blksize = NFSSVC_MAXBLKSIZE;
                i.totalram <<= PAGE_SHIFT - 12;
                while (nfsd_max_blksize > i.totalram &&
                       nfsd_max_blksize >= 8*1024*2)
                        nfsd_max_blksize /= 2;
        }
        nfsd_reset_versions();

        nfsd_serv = svc_create_pooled(&nfsd_program, nfsd_max_blksize,
                                      nfsd_last_thread, nfsd, THIS_MODULE);
        if (nfsd_serv == NULL)
                return -ENOMEM;

        set_max_drc();
        do_gettimeofday(&nfssvc_boot);          /* record boot time */
        return err;
}

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

int nfsd_get_nrthreads(int n, int *nthreads)
{
        int i = 0;

        if (nfsd_serv != NULL) {
                for (i = 0; i < nfsd_serv->sv_nrpools && i < n; i++)
                        nthreads[i] = nfsd_serv->sv_pools[i].sp_nrthreads;
        }

        return 0;
}

int nfsd_set_nrthreads(int n, int *nthreads)
{
        int i = 0;
        int tot = 0;
        int err = 0;

        WARN_ON(!mutex_is_locked(&nfsd_mutex));

        if (nfsd_serv == NULL || n <= 0)
                return 0;

        if (n > nfsd_serv->sv_nrpools)
                n = nfsd_serv->sv_nrpools;

        /* enforce a global maximum number of threads */
        tot = 0;
        for (i = 0; i < n; i++) {
                if (nthreads[i] > NFSD_MAXSERVS)
                        nthreads[i] = NFSD_MAXSERVS;
                tot += nthreads[i];
        }
        if (tot > NFSD_MAXSERVS) {
                /* total too large: scale down requested numbers */
                for (i = 0; i < n && tot > 0; i++) {
                        int new = nthreads[i] * NFSD_MAXSERVS / tot;
                        tot -= (nthreads[i] - new);
                        nthreads[i] = new;
                }
                for (i = 0; i < n && tot > 0; i++) {
                        nthreads[i]--;
                        tot--;
                }
        }

        /*
         * There must always be a thread in pool 0; the admin
         * can't shut down NFS completely using pool_threads.
         */
        if (nthreads[0] == 0)
                nthreads[0] = 1;

        /* apply the new numbers */
        svc_get(nfsd_serv);
        for (i = 0; i < n; i++) {
                err = svc_set_num_threads(nfsd_serv, &nfsd_serv->sv_pools[i],
                                          nthreads[i]);
                if (err)
                        break;
        }
        svc_destroy(nfsd_serv);

        return err;
}

/*
 * Adjust the number of threads and return the new number of threads.
 * This is also the function that starts the server if necessary, if
 * this is the first time nrservs is nonzero.
 */
int
nfsd_svc(unsigned short port, int nrservs)
{
        int     error;
        bool    nfsd_up_before;

        mutex_lock(&nfsd_mutex);
        dprintk("nfsd: creating service\n");
        if (nrservs <= 0)
                nrservs = 0;
        if (nrservs > NFSD_MAXSERVS)
                nrservs = NFSD_MAXSERVS;
        error = 0;
        if (nrservs == 0 && nfsd_serv == NULL)
                goto out;

        error = nfsd_create_serv();
        if (error)
                goto out;

        nfsd_up_before = nfsd_up;

        error = nfsd_startup(port, nrservs);
        if (error)
                goto out_destroy;
        error = svc_set_num_threads(nfsd_serv, NULL, nrservs);
        if (error)
                goto out_shutdown;
        /* We are holding a reference to nfsd_serv which
         * we don't want to count in the return value,
         * so subtract 1
         */
        error = nfsd_serv->sv_nrthreads - 1;
out_shutdown:
        if (error < 0 && !nfsd_up_before)
                nfsd_shutdown();
out_destroy:
        svc_destroy(nfsd_serv);         /* Release server */
out:
        mutex_unlock(&nfsd_mutex);
        return error;
}


/*
 * This is the NFS server kernel thread
 */
static int
nfsd(void *vrqstp)
{
        struct svc_rqst *rqstp = (struct svc_rqst *) vrqstp;
        int err, preverr = 0;

        /* Lock module and set up kernel thread */
        mutex_lock(&nfsd_mutex);

        /* At this point, the thread shares current->fs
         * with the init process. We need to create files with a
         * umask of 0 instead of init's umask. */
        if (unshare_fs_struct() < 0) {
                printk("Unable to start nfsd thread: out of memory\n");
                goto out;
        }

        current->fs->umask = 0;

        /*
         * thread is spawned with all signals set to SIG_IGN, re-enable
         * the ones that will bring down the thread
         */
        allow_signal(SIGKILL);
        allow_signal(SIGHUP);
        allow_signal(SIGINT);
        allow_signal(SIGQUIT);

        nfsdstats.th_cnt++;
        mutex_unlock(&nfsd_mutex);

        /*
         * 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;
        set_freezable();

        /*
         * The main request loop
         */
        for (;;) {
                /*
                 * Find a socket with data available and call its
                 * recvfrom routine.
                 */
                while ((err = svc_recv(rqstp, 60*60*HZ)) == -EAGAIN)
                        ;
                if (err == -EINTR)
                        break;
                else if (err < 0) {
                        if (err != preverr) {
                                printk(KERN_WARNING "%s: unexpected error "
                                        "from svc_recv (%d)\n", __func__, -err);
                                preverr = err;
                        }
                        schedule_timeout_uninterruptible(HZ);
                        continue;
                }

                validate_process_creds();
                svc_process(rqstp);
                validate_process_creds();
        }

        /* Clear signals before calling svc_exit_thread() */
        flush_signals(current);

        mutex_lock(&nfsd_mutex);
        nfsdstats.th_cnt --;

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

        /* Release module */
        mutex_unlock(&nfsd_mutex);
        module_put_and_exit(0);
        return 0;
}

static __be32 map_new_errors(u32 vers, __be32 nfserr)
{
        if (nfserr == nfserr_jukebox && vers == 2)
                return nfserr_dropit;
        if (nfserr == nfserr_wrongsec && vers < 4)
                return nfserr_acces;
        return nfserr;
}

int
nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
{
        struct svc_procedure    *proc;
        kxdrproc_t              xdr;
        __be32                  nfserr;
        __be32                  *nfserrp;

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

        /*
         * Give the xdr decoder a chance to change this if it wants
         * (necessary in the NFSv4.0 compound case)
         */
        rqstp->rq_cachetype = proc->pc_cachetype;
        /* Decode arguments */
        xdr = proc->pc_decode;
        if (xdr && !xdr(rqstp, (__be32*)rqstp->rq_arg.head[0].iov_base,
                        rqstp->rq_argp)) {
                dprintk("nfsd: failed to decode arguments!\n");
                *statp = rpc_garbage_args;
                return 1;
        }

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

        /* 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(__be32);

        /* Now call the procedure handler, and encode NFS status. */
        nfserr = proc->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
        nfserr = map_new_errors(rqstp->rq_vers, nfserr);
        if (nfserr == nfserr_dropit || rqstp->rq_dropme) {
                dprintk("nfsd: Dropping request; may be revisited later\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;
}

int nfsd_pool_stats_open(struct inode *inode, struct file *file)
{
        int ret;
        mutex_lock(&nfsd_mutex);
        if (nfsd_serv == NULL) {
                mutex_unlock(&nfsd_mutex);
                return -ENODEV;
        }
        /* bump up the psudo refcount while traversing */
        svc_get(nfsd_serv);
        ret = svc_pool_stats_open(nfsd_serv, file);
        mutex_unlock(&nfsd_mutex);
        return ret;
}

int nfsd_pool_stats_release(struct inode *inode, struct file *file)
{
        int ret = seq_release(inode, file);
        mutex_lock(&nfsd_mutex);
        /* this function really, really should have been called svc_put() */
        svc_destroy(nfsd_serv);
        mutex_unlock(&nfsd_mutex);
        return ret;
}