/* AFS superblock handling
 *
 * Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.
 *
 * This software may be freely redistributed under the terms of the
 * GNU General Public License.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * Authors: David Howells <dhowells@redhat.com>
 *          David Woodhouse <dwmw2@infradead.org>
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/parser.h>
#include <linux/statfs.h>
#include <linux/sched.h>
#include "internal.h"

#define AFS_FS_MAGIC 0x6B414653 /* 'kAFS' */

static void afs_i_init_once(void *foo);
static struct dentry *afs_mount(struct file_system_type *fs_type,
                      int flags, const char *dev_name, void *data);
static struct inode *afs_alloc_inode(struct super_block *sb);
static void afs_put_super(struct super_block *sb);
static void afs_destroy_inode(struct inode *inode);
static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);

struct file_system_type afs_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "afs",
        .mount          = afs_mount,
        .kill_sb        = kill_anon_super,
        .fs_flags       = 0,
};

static const struct super_operations afs_super_ops = {
        .statfs         = afs_statfs,
        .alloc_inode    = afs_alloc_inode,
        .drop_inode     = afs_drop_inode,
        .destroy_inode  = afs_destroy_inode,
        .evict_inode    = afs_evict_inode,
        .put_super      = afs_put_super,
        .show_options   = generic_show_options,
};

static struct kmem_cache *afs_inode_cachep;
static atomic_t afs_count_active_inodes;

enum {
        afs_no_opt,
        afs_opt_cell,
        afs_opt_rwpath,
        afs_opt_vol,
        afs_opt_autocell,
};

static const match_table_t afs_options_list = {
        { afs_opt_cell,         "cell=%s"       },
        { afs_opt_rwpath,       "rwpath"        },
        { afs_opt_vol,          "vol=%s"        },
        { afs_opt_autocell,     "autocell"      },
        { afs_no_opt,           NULL            },
};

/*
 * initialise the filesystem
 */
int __init afs_fs_init(void)
{
        int ret;

        _enter("");

        /* create ourselves an inode cache */
        atomic_set(&afs_count_active_inodes, 0);

        ret = -ENOMEM;
        afs_inode_cachep = kmem_cache_create("afs_inode_cache",
                                             sizeof(struct afs_vnode),
                                             0,
                                             SLAB_HWCACHE_ALIGN,
                                             afs_i_init_once);
        if (!afs_inode_cachep) {
                printk(KERN_NOTICE "kAFS: Failed to allocate inode cache\n");
                return ret;
        }

        /* now export our filesystem to lesser mortals */
        ret = register_filesystem(&afs_fs_type);
        if (ret < 0) {
                kmem_cache_destroy(afs_inode_cachep);
                _leave(" = %d", ret);
                return ret;
        }

        _leave(" = 0");
        return 0;
}

/*
 * clean up the filesystem
 */
void __exit afs_fs_exit(void)
{
        _enter("");

        afs_mntpt_kill_timer();
        unregister_filesystem(&afs_fs_type);

        if (atomic_read(&afs_count_active_inodes) != 0) {
                printk("kAFS: %d active inode objects still present\n",
                       atomic_read(&afs_count_active_inodes));
                BUG();
        }

        kmem_cache_destroy(afs_inode_cachep);
        _leave("");
}

/*
 * parse the mount options
 * - this function has been shamelessly adapted from the ext3 fs which
 *   shamelessly adapted it from the msdos fs
 */
static int afs_parse_options(struct afs_mount_params *params,
                             char *options, const char **devname)
{
        struct afs_cell *cell;
        substring_t args[MAX_OPT_ARGS];
        char *p;
        int token;

        _enter("%s", options);

        options[PAGE_SIZE - 1] = 0;

        while ((p = strsep(&options, ","))) {
                if (!*p)
                        continue;

                token = match_token(p, afs_options_list, args);
                switch (token) {
                case afs_opt_cell:
                        cell = afs_cell_lookup(args[0].from,
                                               args[0].to - args[0].from,
                                               false);
                        if (IS_ERR(cell))
                                return PTR_ERR(cell);
                        afs_put_cell(params->cell);
                        params->cell = cell;
                        break;

                case afs_opt_rwpath:
                        params->rwpath = 1;
                        break;

                case afs_opt_vol:
                        *devname = args[0].from;
                        break;

                case afs_opt_autocell:
                        params->autocell = 1;
                        break;

                default:
                        printk(KERN_ERR "kAFS:"
                               " Unknown or invalid mount option: '%s'\n", p);
                        return -EINVAL;
                }
        }

        _leave(" = 0");
        return 0;
}

/*
 * parse a device name to get cell name, volume name, volume type and R/W
 * selector
 * - this can be one of the following:
 *      "%[cell:]volume[.]"             R/W volume
 *      "#[cell:]volume[.]"             R/O or R/W volume (rwpath=0),
 *                                       or R/W (rwpath=1) volume
 *      "%[cell:]volume.readonly"       R/O volume
 *      "#[cell:]volume.readonly"       R/O volume
 *      "%[cell:]volume.backup"         Backup volume
 *      "#[cell:]volume.backup"         Backup volume
 */
static int afs_parse_device_name(struct afs_mount_params *params,
                                 const char *name)
{
        struct afs_cell *cell;
        const char *cellname, *suffix;
        int cellnamesz;

        _enter(",%s", name);

        if (!name) {
                printk(KERN_ERR "kAFS: no volume name specified\n");
                return -EINVAL;
        }

        if ((name[0] != '%' && name[0] != '#') || !name[1]) {
                printk(KERN_ERR "kAFS: unparsable volume name\n");
                return -EINVAL;
        }

        /* determine the type of volume we're looking for */
        params->type = AFSVL_ROVOL;
        params->force = false;
        if (params->rwpath || name[0] == '%') {
                params->type = AFSVL_RWVOL;
                params->force = true;
        }
        name++;

        /* split the cell name out if there is one */
        params->volname = strchr(name, ':');
        if (params->volname) {
                cellname = name;
                cellnamesz = params->volname - name;
                params->volname++;
        } else {
                params->volname = name;
                cellname = NULL;
                cellnamesz = 0;
        }

        /* the volume type is further affected by a possible suffix */
        suffix = strrchr(params->volname, '.');
        if (suffix) {
                if (strcmp(suffix, ".readonly") == 0) {
                        params->type = AFSVL_ROVOL;
                        params->force = true;
                } else if (strcmp(suffix, ".backup") == 0) {
                        params->type = AFSVL_BACKVOL;
                        params->force = true;
                } else if (suffix[1] == 0) {
                } else {
                        suffix = NULL;
                }
        }

        params->volnamesz = suffix ?
                suffix - params->volname : strlen(params->volname);

        _debug("cell %*.*s [%p]",
               cellnamesz, cellnamesz, cellname ?: "", params->cell);

        /* lookup the cell record */
        if (cellname || !params->cell) {
                cell = afs_cell_lookup(cellname, cellnamesz, true);
                if (IS_ERR(cell)) {
                        printk(KERN_ERR "kAFS: unable to lookup cell '%*.*s'\n",
                               cellnamesz, cellnamesz, cellname ?: "");
                        return PTR_ERR(cell);
                }
                afs_put_cell(params->cell);
                params->cell = cell;
        }

        _debug("CELL:%s [%p] VOLUME:%*.*s SUFFIX:%s TYPE:%d%s",
               params->cell->name, params->cell,
               params->volnamesz, params->volnamesz, params->volname,
               suffix ?: "-", params->type, params->force ? " FORCE" : "");

        return 0;
}

/*
 * check a superblock to see if it's the one we're looking for
 */
static int afs_test_super(struct super_block *sb, void *data)
{
        struct afs_mount_params *params = data;
        struct afs_super_info *as = sb->s_fs_info;

        return as->volume == params->volume;
}

/*
 * fill in the superblock
 */
static int afs_fill_super(struct super_block *sb, void *data)
{
        struct afs_mount_params *params = data;
        struct afs_super_info *as = NULL;
        struct afs_fid fid;
        struct dentry *root = NULL;
        struct inode *inode = NULL;
        int ret;

        _enter("");

        /* allocate a superblock info record */
        as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
        if (!as) {
                _leave(" = -ENOMEM");
                return -ENOMEM;
        }

        afs_get_volume(params->volume);
        as->volume = params->volume;

        /* fill in the superblock */
        sb->s_blocksize         = PAGE_CACHE_SIZE;
        sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
        sb->s_magic             = AFS_FS_MAGIC;
        sb->s_op                = &afs_super_ops;
        sb->s_fs_info           = as;
        sb->s_bdi               = &as->volume->bdi;

        /* allocate the root inode and dentry */
        fid.vid         = as->volume->vid;
        fid.vnode       = 1;
        fid.unique      = 1;
        inode = afs_iget(sb, params->key, &fid, NULL, NULL);
        if (IS_ERR(inode))
                goto error_inode;

        if (params->autocell)
                set_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(inode)->flags);

        ret = -ENOMEM;
        root = d_alloc_root(inode);
        if (!root)
                goto error;

        sb->s_d_op = &afs_fs_dentry_operations;
        sb->s_root = root;

        _leave(" = 0");
        return 0;

error_inode:
        ret = PTR_ERR(inode);
        inode = NULL;
error:
        iput(inode);
        afs_put_volume(as->volume);
        kfree(as);

        sb->s_fs_info = NULL;

        _leave(" = %d", ret);
        return ret;
}

/*
 * get an AFS superblock
 */
static struct dentry *afs_mount(struct file_system_type *fs_type,
                      int flags, const char *dev_name, void *options)
{
        struct afs_mount_params params;
        struct super_block *sb;
        struct afs_volume *vol;
        struct key *key;
        char *new_opts = kstrdup(options, GFP_KERNEL);
        int ret;

        _enter(",,%s,%p", dev_name, options);

        memset(&params, 0, sizeof(params));

        /* parse the options and device name */
        if (options) {
                ret = afs_parse_options(&params, options, &dev_name);
                if (ret < 0)
                        goto error;
        }

        ret = afs_parse_device_name(&params, dev_name);
        if (ret < 0)
                goto error;

        /* try and do the mount securely */
        key = afs_request_key(params.cell);
        if (IS_ERR(key)) {
                _leave(" = %ld [key]", PTR_ERR(key));
                ret = PTR_ERR(key);
                goto error;
        }
        params.key = key;

        /* parse the device name */
        vol = afs_volume_lookup(&params);
        if (IS_ERR(vol)) {
                ret = PTR_ERR(vol);
                goto error;
        }
        params.volume = vol;

        /* allocate a deviceless superblock */
        sb = sget(fs_type, afs_test_super, set_anon_super, &params);
        if (IS_ERR(sb)) {
                ret = PTR_ERR(sb);
                goto error;
        }

        if (!sb->s_root) {
                /* initial superblock/root creation */
                _debug("create");
                sb->s_flags = flags;
                ret = afs_fill_super(sb, &params);
                if (ret < 0) {
                        deactivate_locked_super(sb);
                        goto error;
                }
                save_mount_options(sb, new_opts);
                sb->s_flags |= MS_ACTIVE;
        } else {
                _debug("reuse");
                ASSERTCMP(sb->s_flags, &, MS_ACTIVE);
        }

        afs_put_volume(params.volume);
        afs_put_cell(params.cell);
        kfree(new_opts);
        _leave(" = 0 [%p]", sb);
        return dget(sb->s_root);

error:
        afs_put_volume(params.volume);
        afs_put_cell(params.cell);
        key_put(params.key);
        kfree(new_opts);
        _leave(" = %d", ret);
        return ERR_PTR(ret);
}

/*
 * finish the unmounting process on the superblock
 */
static void afs_put_super(struct super_block *sb)
{
        struct afs_super_info *as = sb->s_fs_info;

        _enter("");

        afs_put_volume(as->volume);

        _leave("");
}

/*
 * initialise an inode cache slab element prior to any use
 */
static void afs_i_init_once(void *_vnode)
{
        struct afs_vnode *vnode = _vnode;

        memset(vnode, 0, sizeof(*vnode));
        inode_init_once(&vnode->vfs_inode);
        init_waitqueue_head(&vnode->update_waitq);
        mutex_init(&vnode->permits_lock);
        mutex_init(&vnode->validate_lock);
        spin_lock_init(&vnode->writeback_lock);
        spin_lock_init(&vnode->lock);
        INIT_LIST_HEAD(&vnode->writebacks);
        INIT_LIST_HEAD(&vnode->pending_locks);
        INIT_LIST_HEAD(&vnode->granted_locks);
        INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
        INIT_WORK(&vnode->cb_broken_work, afs_broken_callback_work);
}

/*
 * allocate an AFS inode struct from our slab cache
 */
static struct inode *afs_alloc_inode(struct super_block *sb)
{
        struct afs_vnode *vnode;

        vnode = kmem_cache_alloc(afs_inode_cachep, GFP_KERNEL);
        if (!vnode)
                return NULL;

        atomic_inc(&afs_count_active_inodes);

        memset(&vnode->fid, 0, sizeof(vnode->fid));
        memset(&vnode->status, 0, sizeof(vnode->status));

        vnode->volume           = NULL;
        vnode->update_cnt       = 0;
        vnode->flags            = 1 << AFS_VNODE_UNSET;
        vnode->cb_promised      = false;

        _leave(" = %p", &vnode->vfs_inode);
        return &vnode->vfs_inode;
}

static void afs_i_callback(struct rcu_head *head)
{
        struct inode *inode = container_of(head, struct inode, i_rcu);
        struct afs_vnode *vnode = AFS_FS_I(inode);
        INIT_LIST_HEAD(&inode->i_dentry);
        kmem_cache_free(afs_inode_cachep, vnode);
}

/*
 * destroy an AFS inode struct
 */
static void afs_destroy_inode(struct inode *inode)
{
        struct afs_vnode *vnode = AFS_FS_I(inode);

        _enter("%p{%x:%u}", inode, vnode->fid.vid, vnode->fid.vnode);

        _debug("DESTROY INODE %p", inode);

        ASSERTCMP(vnode->server, ==, NULL);

        call_rcu(&inode->i_rcu, afs_i_callback);
        atomic_dec(&afs_count_active_inodes);
}

/*
 * return information about an AFS volume
 */
static int afs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
        struct afs_volume_status vs;
        struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
        struct key *key;
        int ret;

        key = afs_request_key(vnode->volume->cell);
        if (IS_ERR(key))
                return PTR_ERR(key);

        ret = afs_vnode_get_volume_status(vnode, key, &vs);
        key_put(key);
        if (ret < 0) {
                _leave(" = %d", ret);
                return ret;
        }

        buf->f_type     = dentry->d_sb->s_magic;
        buf->f_bsize    = AFS_BLOCK_SIZE;
        buf->f_namelen  = AFSNAMEMAX - 1;

        if (vs.max_quota == 0)
                buf->f_blocks = vs.part_max_blocks;
        else
                buf->f_blocks = vs.max_quota;
        buf->f_bavail = buf->f_bfree = buf->f_blocks - vs.blocks_in_use;
        return 0;
}