v9fs.c

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/*
 *  linux/fs/9p/v9fs.c
 *
 *  This file contains functions assisting in mapping VFS to 9P2000
 *
 *  Copyright (C) 2004-2008 by Eric Van Hensbergen <[email protected]>
 *  Copyright (C) 2002 by Ron Minnich <[email protected]>
 *
 *  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_trans, Opt_cache, Opt_cachetag,
    /* Options that take no arguments */
    Opt_nodevmap,
    /* Cache options */
    Opt_cache_loose, Opt_fscache,
    /* 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_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, "none")) {
        version = CACHE_NONE;
        p9_debug(P9_DEBUG_9P, "Cache mode: none\n");
    } else
        pr_info("Unknown Cache mode %s\n", s);
    return version;
}

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 = option;
            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 = option;
            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_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 {
                v9ses->flags |= V9FS_ACCESS_SINGLE;
                v9ses->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;
                }
            }

            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;
}

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

    v9ses->uname = kstrdup(V9FS_DEFUSER, GFP_KERNEL);
    if (!v9ses->uname)
        return ERR_PTR(-ENOMEM);

    v9ses->aname = kstrdup(V9FS_DEFANAME, GFP_KERNEL);
    if (!v9ses->aname) {
        kfree(v9ses->uname);
        return ERR_PTR(-ENOMEM);
    }
    init_rwsem(&v9ses->rename_sem);

    rc = bdi_setup_and_register(&v9ses->bdi, "9p", BDI_CAP_MAP_COPY);
    if (rc) {
        kfree(v9ses->aname);
        kfree(v9ses->uname);
        return ERR_PTR(rc);
    }

    spin_lock(&v9fs_sessionlist_lock);
    list_add(&v9ses->slist, &v9fs_sessionlist);
    spin_unlock(&v9fs_sessionlist_lock);

    v9ses->uid = ~0;
    v9ses->dfltuid = V9FS_DEFUID;
    v9ses->dfltgid = V9FS_DEFGID;

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

    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) {
        retval = rc;
        goto error;
    }

    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 = ~0;
    }
    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, ~0,
                            v9ses->aname);
    if (IS_ERR(fid)) {
        retval = PTR_ERR(fid);
        fid = NULL;
        p9_debug(P9_DEBUG_ERROR, "cannot attach\n");
        goto error;
    }

    if ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_SINGLE)
        fid->uid = v9ses->uid;
    else
        fid->uid = ~0;

#ifdef CONFIG_9P_FSCACHE
    /* register the session for caching */
    v9fs_cache_session_get_cookie(v9ses);
#endif

    return fid;

error:
    bdi_destroy(&v9ses->bdi);
    return ERR_PTR(retval);
}

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);
}

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

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

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,
};

static int 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;
}

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);
}

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),
                      v9fs_inode_init_once);
    if (!v9fs_inode_cache)
        return -ENOMEM;

    return 0;
}

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
    return fscache_register_netfs(&v9fs_cache_netfs);
#else
    return ret;
#endif
}

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

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;
}

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 <[email protected]>");
MODULE_AUTHOR("Ron Minnich <[email protected]>");
MODULE_LICENSE("GPL");