/* 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 <linux/nsproxy.h>
#include <linux/magic.h>
#include <net/net_namespace.h>
#include "internal.h"

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 void afs_kill_super(struct super_block *sb);
static struct inode *afs_alloc_inode(struct super_block *sb);
static void afs_destroy_inode(struct inode *inode);
static int afs_statfs(struct dentry *dentry, struct kstatfs *buf);
static int afs_show_devname(struct seq_file *m, struct dentry *root);
static int afs_show_options(struct seq_file *m, struct dentry *root);

struct file_system_type afs_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "afs",
        .mount          = afs_mount,
        .kill_sb        = afs_kill_super,
        .fs_flags       = 0,
};
MODULE_ALIAS_FS("afs");

int afs_net_id;

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,
        .show_devname   = afs_show_devname,
        .show_options   = afs_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_dyn,
        afs_opt_rwpath,
        afs_opt_vol,
        afs_opt_autocell,
};

static const match_table_t afs_options_list = {
        { afs_opt_cell,         "cell=%s"       },
        { afs_opt_dyn,          "dyn"           },
        { 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|SLAB_ACCOUNT,
                                             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 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();
        }

        /*
         * Make sure all delayed rcu free inodes are flushed before we
         * destroy cache.
         */
        rcu_barrier();
        kmem_cache_destroy(afs_inode_cachep);
        _leave("");
}

/*
 * Display the mount device name in /proc/mounts.
 */
static int afs_show_devname(struct seq_file *m, struct dentry *root)
{
        struct afs_super_info *as = AFS_FS_S(root->d_sb);
        struct afs_volume *volume = as->volume;
        struct afs_cell *cell = as->cell;
        const char *suf = "";
        char pref = '%';

        if (as->dyn_root) {
                seq_puts(m, "none");
                return 0;
        }

        switch (volume->type) {
        case AFSVL_RWVOL:
                break;
        case AFSVL_ROVOL:
                pref = '#';
                if (volume->type_force)
                        suf = ".readonly";
                break;
        case AFSVL_BACKVOL:
                pref = '#';
                suf = ".backup";
                break;
        }

        seq_printf(m, "%c%s:%s%s", pref, cell->name, volume->name, suf);
        return 0;
}

/*
 * Display the mount options in /proc/mounts.
 */
static int afs_show_options(struct seq_file *m, struct dentry *root)
{
        struct afs_super_info *as = AFS_FS_S(root->d_sb);

        if (as->dyn_root)
                seq_puts(m, ",dyn");
        if (test_bit(AFS_VNODE_AUTOCELL, &AFS_FS_I(d_inode(root))->flags))
                seq_puts(m, ",autocell");
        return 0;
}

/*
 * 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:
                        rcu_read_lock();
                        cell = afs_lookup_cell_rcu(params->net,
                                                   args[0].from,
                                                   args[0].to - args[0].from);
                        rcu_read_unlock();
                        if (IS_ERR(cell))
                                return PTR_ERR(cell);
                        afs_put_cell(params->net, params->cell);
                        params->cell = cell;
                        break;

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

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

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

                case afs_opt_dyn:
                        params->dyn_root = true;
                        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_lookup_cell(params->net, cellname, cellnamesz,
                                       NULL, false);
                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->net, 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_super_info *as1 = data;
        struct afs_super_info *as = AFS_FS_S(sb);

        return (as->net_ns == as1->net_ns &&
                as->volume &&
                as->volume->vid == as1->volume->vid &&
                !as->dyn_root);
}

static int afs_dynroot_test_super(struct super_block *sb, void *data)
{
        struct afs_super_info *as1 = data;
        struct afs_super_info *as = AFS_FS_S(sb);

        return (as->net_ns == as1->net_ns &&
                as->dyn_root);
}

static int afs_set_super(struct super_block *sb, void *data)
{
        struct afs_super_info *as = data;

        sb->s_fs_info = as;
        return set_anon_super(sb, NULL);
}

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

        _enter("");

        /* fill in the superblock */
        sb->s_blocksize         = PAGE_SIZE;
        sb->s_blocksize_bits    = PAGE_SHIFT;
        sb->s_magic             = AFS_FS_MAGIC;
        sb->s_op                = &afs_super_ops;
        if (!as->dyn_root)
                sb->s_xattr     = afs_xattr_handlers;
        ret = super_setup_bdi(sb);
        if (ret)
                return ret;
        sb->s_bdi->ra_pages     = VM_MAX_READAHEAD * 1024 / PAGE_SIZE;

        /* allocate the root inode and dentry */
        if (as->dyn_root) {
                inode = afs_iget_pseudo_dir(sb, true);
                sb->s_flags     |= SB_RDONLY;
        } else {
                sprintf(sb->s_id, "%u", as->volume->vid);
                afs_activate_volume(as->volume);
                fid.vid         = as->volume->vid;
                fid.vnode       = 1;
                fid.unique      = 1;
                inode = afs_iget(sb, params->key, &fid, NULL, NULL, NULL);
        }

        if (IS_ERR(inode))
                return PTR_ERR(inode);

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

        ret = -ENOMEM;
        sb->s_root = d_make_root(inode);
        if (!sb->s_root)
                goto error;

        if (as->dyn_root) {
                sb->s_d_op = &afs_dynroot_dentry_operations;
                ret = afs_dynroot_populate(sb);
                if (ret < 0)
                        goto error;
        } else {
                sb->s_d_op = &afs_fs_dentry_operations;
        }

        _leave(" = 0");
        return 0;

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

static struct afs_super_info *afs_alloc_sbi(struct afs_mount_params *params)
{
        struct afs_super_info *as;

        as = kzalloc(sizeof(struct afs_super_info), GFP_KERNEL);
        if (as) {
                as->net_ns = get_net(params->net_ns);
                if (params->dyn_root)
                        as->dyn_root = true;
                else
                        as->cell = afs_get_cell(params->cell);
        }
        return as;
}

static void afs_destroy_sbi(struct afs_super_info *as)
{
        if (as) {
                afs_put_volume(as->cell, as->volume);
                afs_put_cell(afs_net(as->net_ns), as->cell);
                put_net(as->net_ns);
                kfree(as);
        }
}

static void afs_kill_super(struct super_block *sb)
{
        struct afs_super_info *as = AFS_FS_S(sb);
        struct afs_net *net = afs_net(as->net_ns);

        if (as->dyn_root)
                afs_dynroot_depopulate(sb);
        
        /* Clear the callback interests (which will do ilookup5) before
         * deactivating the superblock.
         */
        if (as->volume)
                afs_clear_callback_interests(net, as->volume->servers);
        kill_anon_super(sb);
        if (as->volume)
                afs_deactivate_volume(as->volume);
        afs_destroy_sbi(as);
}

/*
 * 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 *candidate;
        struct key *key;
        struct afs_super_info *as;
        int ret;

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

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

        ret = -EINVAL;
        if (current->nsproxy->net_ns != &init_net)
                goto error;
        params.net_ns = current->nsproxy->net_ns;
        params.net = afs_net(params.net_ns);
        
        /* parse the options and device name */
        if (options) {
                ret = afs_parse_options(&params, options, &dev_name);
                if (ret < 0)
                        goto error;
        }

        if (!params.dyn_root) {
                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;
        }

        /* allocate a superblock info record */
        ret = -ENOMEM;
        as = afs_alloc_sbi(&params);
        if (!as)
                goto error_key;

        if (!params.dyn_root) {
                /* Assume we're going to need a volume record; at the very
                 * least we can use it to update the volume record if we have
                 * one already.  This checks that the volume exists within the
                 * cell.
                 */
                candidate = afs_create_volume(&params);
                if (IS_ERR(candidate)) {
                        ret = PTR_ERR(candidate);
                        goto error_as;
                }

                as->volume = candidate;
        }

        /* allocate a deviceless superblock */
        sb = sget(fs_type,
                  as->dyn_root ? afs_dynroot_test_super : afs_test_super,
                  afs_set_super, flags, as);
        if (IS_ERR(sb)) {
                ret = PTR_ERR(sb);
                goto error_as;
        }

        if (!sb->s_root) {
                /* initial superblock/root creation */
                _debug("create");
                ret = afs_fill_super(sb, &params);
                if (ret < 0)
                        goto error_sb;
                as = NULL;
                sb->s_flags |= SB_ACTIVE;
        } else {
                _debug("reuse");
                ASSERTCMP(sb->s_flags, &, SB_ACTIVE);
                afs_destroy_sbi(as);
                as = NULL;
        }

        afs_put_cell(params.net, params.cell);
        key_put(params.key);
        _leave(" = 0 [%p]", sb);
        return dget(sb->s_root);

error_sb:
        deactivate_locked_super(sb);
        goto error_key;
error_as:
        afs_destroy_sbi(as);
error_key:
        key_put(params.key);
error:
        afs_put_cell(params.net, params.cell);
        _leave(" = %d", ret);
        return ERR_PTR(ret);
}

/*
 * Initialise an inode cache slab element prior to any use.  Note that
 * afs_alloc_inode() *must* reset anything that could incorrectly leak from one
 * inode to another.
 */
static void afs_i_init_once(void *_vnode)
{
        struct afs_vnode *vnode = _vnode;

        memset(vnode, 0, sizeof(*vnode));
        inode_init_once(&vnode->vfs_inode);
        mutex_init(&vnode->io_lock);
        init_rwsem(&vnode->validate_lock);
        spin_lock_init(&vnode->wb_lock);
        spin_lock_init(&vnode->lock);
        INIT_LIST_HEAD(&vnode->wb_keys);
        INIT_LIST_HEAD(&vnode->pending_locks);
        INIT_LIST_HEAD(&vnode->granted_locks);
        INIT_DELAYED_WORK(&vnode->lock_work, afs_lock_work);
        seqlock_init(&vnode->cb_lock);
}

/*
 * 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);

        /* Reset anything that shouldn't leak from one inode to the next. */
        memset(&vnode->fid, 0, sizeof(vnode->fid));
        memset(&vnode->status, 0, sizeof(vnode->status));

        vnode->volume           = NULL;
        vnode->lock_key         = NULL;
        vnode->permit_cache     = NULL;
        vnode->cb_interest      = NULL;
#ifdef CONFIG_AFS_FSCACHE
        vnode->cache            = NULL;
#endif

        vnode->flags            = 1 << AFS_VNODE_UNSET;
        vnode->cb_type          = 0;
        vnode->lock_state       = AFS_VNODE_LOCK_NONE;

        _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);
        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->cb_interest, ==, 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_super_info *as = AFS_FS_S(dentry->d_sb);
        struct afs_fs_cursor fc;
        struct afs_volume_status vs;
        struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
        struct key *key;
        int ret;

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

        if (as->dyn_root) {
                buf->f_blocks   = 1;
                buf->f_bavail   = 0;
                buf->f_bfree    = 0;
                return 0;
        }

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

        ret = -ERESTARTSYS;
        if (afs_begin_vnode_operation(&fc, vnode, key)) {
                fc.flags |= AFS_FS_CURSOR_NO_VSLEEP;
                while (afs_select_fileserver(&fc)) {
                        fc.cb_break = afs_calc_vnode_cb_break(vnode);
                        afs_fs_get_volume_status(&fc, &vs);
                }

                afs_check_for_remote_deletion(&fc, fc.vnode);
                afs_vnode_commit_status(&fc, vnode, fc.cb_break);
                ret = afs_end_vnode_operation(&fc);
        }

        key_put(key);

        if (ret == 0) {
                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 ret;
}