/*
 *  linux/fs/9p/v9fs.c
 *
 *  This file contains functions assisting in mapping VFS to 9P2000
 *
 *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
 *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/parser.h>
#include <linux/idr.h>
#include <linux/slab.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>
#include "v9fs.h"
#include "v9fs_vfs.h"
#include "cache.h"

static DEFINE_SPINLOCK(v9fs_sessionlist_lock);
static LIST_HEAD(v9fs_sessionlist);
struct kmem_cache *v9fs_inode_cache;

/*
 * Option Parsing (code inspired by NFS code)
 *  NOTE: each transport will parse its own options
 */

enum {
        /* Options that take integer arguments */
        Opt_debug, Opt_dfltuid, Opt_dfltgid, Opt_afid,
        /* String options */
        Opt_uname, Opt_remotename, Opt_cache, Opt_cachetag,
        /* Options that take no arguments */
        Opt_nodevmap,
        /* Cache options */
        Opt_cache_loose, Opt_fscache, Opt_mmap,
        /* Access options */
        Opt_access, Opt_posixacl,
        /* Error token */
        Opt_err
};

static const match_table_t tokens = {
        {Opt_debug, "debug=%x"},
        {Opt_dfltuid, "dfltuid=%u"},
        {Opt_dfltgid, "dfltgid=%u"},
        {Opt_afid, "afid=%u"},
        {Opt_uname, "uname=%s"},
        {Opt_remotename, "aname=%s"},
        {Opt_nodevmap, "nodevmap"},
        {Opt_cache, "cache=%s"},
        {Opt_cache_loose, "loose"},
        {Opt_fscache, "fscache"},
        {Opt_mmap, "mmap"},
        {Opt_cachetag, "cachetag=%s"},
        {Opt_access, "access=%s"},
        {Opt_posixacl, "posixacl"},
        {Opt_err, NULL}
};

/* Interpret mount options for cache mode */
static int get_cache_mode(char *s)
{
        int version = -EINVAL;

        if (!strcmp(s, "loose")) {
                version = CACHE_LOOSE;
                p9_debug(P9_DEBUG_9P, "Cache mode: loose\n");
        } else if (!strcmp(s, "fscache")) {
                version = CACHE_FSCACHE;
                p9_debug(P9_DEBUG_9P, "Cache mode: fscache\n");
        } else if (!strcmp(s, "mmap")) {
                version = CACHE_MMAP;
                p9_debug(P9_DEBUG_9P, "Cache mode: mmap\n");
        } else if (!strcmp(s, "none")) {
                version = CACHE_NONE;
                p9_debug(P9_DEBUG_9P, "Cache mode: none\n");
        } else
                pr_info("Unknown Cache mode %s\n", s);
        return version;
}

/**
 * v9fs_parse_options - parse mount options into session structure
 * @v9ses: existing v9fs session information
 *
 * Return 0 upon success, -ERRNO upon failure.
 */

static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts)
{
        char *options, *tmp_options;
        substring_t args[MAX_OPT_ARGS];
        char *p;
        int option = 0;
        char *s, *e;
        int ret = 0;

        /* setup defaults */
        v9ses->afid = ~0;
        v9ses->debug = 0;
        v9ses->cache = CACHE_NONE;
#ifdef CONFIG_9P_FSCACHE
        v9ses->cachetag = NULL;
#endif

        if (!opts)
                return 0;

        tmp_options = kstrdup(opts, GFP_KERNEL);
        if (!tmp_options) {
                ret = -ENOMEM;
                goto fail_option_alloc;
        }
        options = tmp_options;

        while ((p = strsep(&options, ",")) != NULL) {
                int token, r;
                if (!*p)
                        continue;
                token = match_token(p, tokens, args);
                switch (token) {
                case Opt_debug:
                        r = match_int(&args[0], &option);
                        if (r < 0) {
                                p9_debug(P9_DEBUG_ERROR,
                                         "integer field, but no integer?\n");
                                ret = r;
                                continue;
                        }
                        v9ses->debug = option;
#ifdef CONFIG_NET_9P_DEBUG
                        p9_debug_level = option;
#endif
                        break;

                case Opt_dfltuid:
                        r = match_int(&args[0], &option);
                        if (r < 0) {
                                p9_debug(P9_DEBUG_ERROR,
                                         "integer field, but no integer?\n");
                                ret = r;
                                continue;
                        }
                        v9ses->dfltuid = make_kuid(current_user_ns(), option);
                        if (!uid_valid(v9ses->dfltuid)) {
                                p9_debug(P9_DEBUG_ERROR,
                                         "uid field, but not a uid?\n");
                                ret = -EINVAL;
                                continue;
                        }
                        break;
                case Opt_dfltgid:
                        r = match_int(&args[0], &option);
                        if (r < 0) {
                                p9_debug(P9_DEBUG_ERROR,
                                         "integer field, but no integer?\n");
                                ret = r;
                                continue;
                        }
                        v9ses->dfltgid = make_kgid(current_user_ns(), option);
                        if (!gid_valid(v9ses->dfltgid)) {
                                p9_debug(P9_DEBUG_ERROR,
                                         "gid field, but not a gid?\n");
                                ret = -EINVAL;
                                continue;
                        }
                        break;
                case Opt_afid:
                        r = match_int(&args[0], &option);
                        if (r < 0) {
                                p9_debug(P9_DEBUG_ERROR,
                                         "integer field, but no integer?\n");
                                ret = r;
                                continue;
                        }
                        v9ses->afid = option;
                        break;
                case Opt_uname:
                        kfree(v9ses->uname);
                        v9ses->uname = match_strdup(&args[0]);
                        if (!v9ses->uname) {
                                ret = -ENOMEM;
                                goto free_and_return;
                        }
                        break;
                case Opt_remotename:
                        kfree(v9ses->aname);
                        v9ses->aname = match_strdup(&args[0]);
                        if (!v9ses->aname) {
                                ret = -ENOMEM;
                                goto free_and_return;
                        }
                        break;
                case Opt_nodevmap:
                        v9ses->nodev = 1;
                        break;
                case Opt_cache_loose:
                        v9ses->cache = CACHE_LOOSE;
                        break;
                case Opt_fscache:
                        v9ses->cache = CACHE_FSCACHE;
                        break;
                case Opt_mmap:
                        v9ses->cache = CACHE_MMAP;
                        break;
                case Opt_cachetag:
#ifdef CONFIG_9P_FSCACHE
                        v9ses->cachetag = match_strdup(&args[0]);
#endif
                        break;
                case Opt_cache:
                        s = match_strdup(&args[0]);
                        if (!s) {
                                ret = -ENOMEM;
                                p9_debug(P9_DEBUG_ERROR,
                                         "problem allocating copy of cache arg\n");
                                goto free_and_return;
                        }
                        ret = get_cache_mode(s);
                        if (ret == -EINVAL) {
                                kfree(s);
                                goto free_and_return;
                        }

                        v9ses->cache = ret;
                        kfree(s);
                        break;

                case Opt_access:
                        s = match_strdup(&args[0]);
                        if (!s) {
                                ret = -ENOMEM;
                                p9_debug(P9_DEBUG_ERROR,
                                         "problem allocating copy of access arg\n");
                                goto free_and_return;
                        }

                        v9ses->flags &= ~V9FS_ACCESS_MASK;
                        if (strcmp(s, "user") == 0)
                                v9ses->flags |= V9FS_ACCESS_USER;
                        else if (strcmp(s, "any") == 0)
                                v9ses->flags |= V9FS_ACCESS_ANY;
                        else if (strcmp(s, "client") == 0) {
                                v9ses->flags |= V9FS_ACCESS_CLIENT;
                        } else {
                                uid_t uid;
                                v9ses->flags |= V9FS_ACCESS_SINGLE;
                                uid = simple_strtoul(s, &e, 10);
                                if (*e != '\0') {
                                        ret = -EINVAL;
                                        pr_info("Unknown access argument %s\n",
                                                s);
                                        kfree(s);
                                        goto free_and_return;
                                }
                                v9ses->uid = make_kuid(current_user_ns(), uid);
                                if (!uid_valid(v9ses->uid)) {
                                        ret = -EINVAL;
                                        pr_info("Uknown uid %s\n", s);
                                        kfree(s);
                                        goto free_and_return;
                                }
                        }

                        kfree(s);
                        break;

                case Opt_posixacl:
#ifdef CONFIG_9P_FS_POSIX_ACL
                        v9ses->flags |= V9FS_POSIX_ACL;
#else
                        p9_debug(P9_DEBUG_ERROR,
                                 "Not defined CONFIG_9P_FS_POSIX_ACL. Ignoring posixacl option\n");
#endif
                        break;

                default:
                        continue;
                }
        }

free_and_return:
        kfree(tmp_options);
fail_option_alloc:
        return ret;
}

/**
 * v9fs_session_init - initialize session
 * @v9ses: session information structure
 * @dev_name: device being mounted
 * @data: options
 *
 */

struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
                  const char *dev_name, char *data)
{
        struct p9_fid *fid;
        int rc = -ENOMEM;

        v9ses->uname = kstrdup(V9FS_DEFUSER, GFP_KERNEL);
        if (!v9ses->uname)
                goto err_names;

        v9ses->aname = kstrdup(V9FS_DEFANAME, GFP_KERNEL);
        if (!v9ses->aname)
                goto err_names;
        init_rwsem(&v9ses->rename_sem);

        rc = bdi_setup_and_register(&v9ses->bdi, "9p");
        if (rc)
                goto err_names;

        v9ses->uid = INVALID_UID;
        v9ses->dfltuid = V9FS_DEFUID;
        v9ses->dfltgid = V9FS_DEFGID;

        v9ses->clnt = p9_client_create(dev_name, data);
        if (IS_ERR(v9ses->clnt)) {
                rc = PTR_ERR(v9ses->clnt);
                p9_debug(P9_DEBUG_ERROR, "problem initializing 9p client\n");
                goto err_bdi;
        }

        v9ses->flags = V9FS_ACCESS_USER;

        if (p9_is_proto_dotl(v9ses->clnt)) {
                v9ses->flags = V9FS_ACCESS_CLIENT;
                v9ses->flags |= V9FS_PROTO_2000L;
        } else if (p9_is_proto_dotu(v9ses->clnt)) {
                v9ses->flags |= V9FS_PROTO_2000U;
        }

        rc = v9fs_parse_options(v9ses, data);
        if (rc < 0)
                goto err_clnt;

        v9ses->maxdata = v9ses->clnt->msize - P9_IOHDRSZ;

        if (!v9fs_proto_dotl(v9ses) &&
            ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_CLIENT)) {
                /*
                 * We support ACCESS_CLIENT only for dotl.
                 * Fall back to ACCESS_USER
                 */
                v9ses->flags &= ~V9FS_ACCESS_MASK;
                v9ses->flags |= V9FS_ACCESS_USER;
        }
        /*FIXME !! */
        /* for legacy mode, fall back to V9FS_ACCESS_ANY */
        if (!(v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) &&
                ((v9ses->flags&V9FS_ACCESS_MASK) == V9FS_ACCESS_USER)) {

                v9ses->flags &= ~V9FS_ACCESS_MASK;
                v9ses->flags |= V9FS_ACCESS_ANY;
                v9ses->uid = INVALID_UID;
        }
        if (!v9fs_proto_dotl(v9ses) ||
                !((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_CLIENT)) {
                /*
                 * We support ACL checks on clinet only if the protocol is
                 * 9P2000.L and access is V9FS_ACCESS_CLIENT.
                 */
                v9ses->flags &= ~V9FS_ACL_MASK;
        }

        fid = p9_client_attach(v9ses->clnt, NULL, v9ses->uname, INVALID_UID,
                                                        v9ses->aname);
        if (IS_ERR(fid)) {
                rc = PTR_ERR(fid);
                p9_debug(P9_DEBUG_ERROR, "cannot attach\n");
                goto err_clnt;
        }

        if ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_SINGLE)
                fid->uid = v9ses->uid;
        else
                fid->uid = INVALID_UID;

#ifdef CONFIG_9P_FSCACHE
        /* register the session for caching */
        v9fs_cache_session_get_cookie(v9ses);
#endif
        spin_lock(&v9fs_sessionlist_lock);
        list_add(&v9ses->slist, &v9fs_sessionlist);
        spin_unlock(&v9fs_sessionlist_lock);

        return fid;

err_clnt:
        p9_client_destroy(v9ses->clnt);
err_bdi:
        bdi_destroy(&v9ses->bdi);
err_names:
        kfree(v9ses->uname);
        kfree(v9ses->aname);
        return ERR_PTR(rc);
}

/**
 * v9fs_session_close - shutdown a session
 * @v9ses: session information structure
 *
 */

void v9fs_session_close(struct v9fs_session_info *v9ses)
{
        if (v9ses->clnt) {
                p9_client_destroy(v9ses->clnt);
                v9ses->clnt = NULL;
        }

#ifdef CONFIG_9P_FSCACHE
        if (v9ses->fscache) {
                v9fs_cache_session_put_cookie(v9ses);
                kfree(v9ses->cachetag);
        }
#endif
        kfree(v9ses->uname);
        kfree(v9ses->aname);

        bdi_destroy(&v9ses->bdi);

        spin_lock(&v9fs_sessionlist_lock);
        list_del(&v9ses->slist);
        spin_unlock(&v9fs_sessionlist_lock);
}

/**
 * v9fs_session_cancel - terminate a session
 * @v9ses: session to terminate
 *
 * mark transport as disconnected and cancel all pending requests.
 */

void v9fs_session_cancel(struct v9fs_session_info *v9ses) {
        p9_debug(P9_DEBUG_ERROR, "cancel session %p\n", v9ses);
        p9_client_disconnect(v9ses->clnt);
}

/**
 * v9fs_session_begin_cancel - Begin terminate of a session
 * @v9ses: session to terminate
 *
 * After this call we don't allow any request other than clunk.
 */

void v9fs_session_begin_cancel(struct v9fs_session_info *v9ses)
{
        p9_debug(P9_DEBUG_ERROR, "begin cancel session %p\n", v9ses);
        p9_client_begin_disconnect(v9ses->clnt);
}

extern int v9fs_error_init(void);

static struct kobject *v9fs_kobj;

#ifdef CONFIG_9P_FSCACHE
/**
 * caches_show - list caches associated with a session
 *
 * Returns the size of buffer written.
 */

static ssize_t caches_show(struct kobject *kobj,
                           struct kobj_attribute *attr,
                           char *buf)
{
        ssize_t n = 0, count = 0, limit = PAGE_SIZE;
        struct v9fs_session_info *v9ses;

        spin_lock(&v9fs_sessionlist_lock);
        list_for_each_entry(v9ses, &v9fs_sessionlist, slist) {
                if (v9ses->cachetag) {
                        n = snprintf(buf, limit, "%s\n", v9ses->cachetag);
                        if (n < 0) {
                                count = n;
                                break;
                        }

                        count += n;
                        limit -= n;
                }
        }

        spin_unlock(&v9fs_sessionlist_lock);
        return count;
}

static struct kobj_attribute v9fs_attr_cache = __ATTR_RO(caches);
#endif /* CONFIG_9P_FSCACHE */

static struct attribute *v9fs_attrs[] = {
#ifdef CONFIG_9P_FSCACHE
        &v9fs_attr_cache.attr,
#endif
        NULL,
};

static struct attribute_group v9fs_attr_group = {
        .attrs = v9fs_attrs,
};

/**
 * v9fs_sysfs_init - Initialize the v9fs sysfs interface
 *
 */

static int __init v9fs_sysfs_init(void)
{
        v9fs_kobj = kobject_create_and_add("9p", fs_kobj);
        if (!v9fs_kobj)
                return -ENOMEM;

        if (sysfs_create_group(v9fs_kobj, &v9fs_attr_group)) {
                kobject_put(v9fs_kobj);
                return -ENOMEM;
        }

        return 0;
}

/**
 * v9fs_sysfs_cleanup - Unregister the v9fs sysfs interface
 *
 */

static void v9fs_sysfs_cleanup(void)
{
        sysfs_remove_group(v9fs_kobj, &v9fs_attr_group);
        kobject_put(v9fs_kobj);
}

static void v9fs_inode_init_once(void *foo)
{
        struct v9fs_inode *v9inode = (struct v9fs_inode *)foo;
#ifdef CONFIG_9P_FSCACHE
        v9inode->fscache = NULL;
#endif
        memset(&v9inode->qid, 0, sizeof(v9inode->qid));
        inode_init_once(&v9inode->vfs_inode);
}

/**
 * v9fs_init_inode_cache - initialize a cache for 9P
 * Returns 0 on success.
 */
static int v9fs_init_inode_cache(void)
{
        v9fs_inode_cache = kmem_cache_create("v9fs_inode_cache",
                                          sizeof(struct v9fs_inode),
                                          0, (SLAB_RECLAIM_ACCOUNT|
                                              SLAB_MEM_SPREAD|SLAB_ACCOUNT),
                                          v9fs_inode_init_once);
        if (!v9fs_inode_cache)
                return -ENOMEM;

        return 0;
}

/**
 * v9fs_destroy_inode_cache - destroy the cache of 9P inode
 *
 */
static void v9fs_destroy_inode_cache(void)
{
        /*
         * Make sure all delayed rcu free inodes are flushed before we
         * destroy cache.
         */
        rcu_barrier();
        kmem_cache_destroy(v9fs_inode_cache);
}

static int v9fs_cache_register(void)
{
        int ret;
        ret = v9fs_init_inode_cache();
        if (ret < 0)
                return ret;
#ifdef CONFIG_9P_FSCACHE
        ret = fscache_register_netfs(&v9fs_cache_netfs);
        if (ret < 0)
                v9fs_destroy_inode_cache();
#endif
        return ret;
}

static void v9fs_cache_unregister(void)
{
        v9fs_destroy_inode_cache();
#ifdef CONFIG_9P_FSCACHE
        fscache_unregister_netfs(&v9fs_cache_netfs);
#endif
}

/**
 * init_v9fs - Initialize module
 *
 */

static int __init init_v9fs(void)
{
        int err;
        pr_info("Installing v9fs 9p2000 file system support\n");
        /* TODO: Setup list of registered trasnport modules */

        err = v9fs_cache_register();
        if (err < 0) {
                pr_err("Failed to register v9fs for caching\n");
                return err;
        }

        err = v9fs_sysfs_init();
        if (err < 0) {
                pr_err("Failed to register with sysfs\n");
                goto out_cache;
        }
        err = register_filesystem(&v9fs_fs_type);
        if (err < 0) {
                pr_err("Failed to register filesystem\n");
                goto out_sysfs_cleanup;
        }

        return 0;

out_sysfs_cleanup:
        v9fs_sysfs_cleanup();

out_cache:
        v9fs_cache_unregister();

        return err;
}

/**
 * exit_v9fs - shutdown module
 *
 */

static void __exit exit_v9fs(void)
{
        v9fs_sysfs_cleanup();
        v9fs_cache_unregister();
        unregister_filesystem(&v9fs_fs_type);
}

module_init(init_v9fs)
module_exit(exit_v9fs)

MODULE_AUTHOR("Latchesar Ionkov <lucho@ionkov.net>");
MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
MODULE_AUTHOR("Ron Minnich <rminnich@lanl.gov>");
MODULE_LICENSE("GPL");