/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2001-2007 Red Hat, Inc.
 *
 * Created by David Woodhouse <dwmw2@infradead.org>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/fs.h>
#include <linux/err.h>
#include <linux/mount.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/jffs2.h>
#include <linux/pagemap.h>
#include <linux/mtd/super.h>
#include <linux/ctype.h>
#include <linux/namei.h>
#include <linux/seq_file.h>
#include <linux/exportfs.h>
#include "compr.h"
#include "nodelist.h"

static void jffs2_put_super(struct super_block *);

static struct kmem_cache *jffs2_inode_cachep;

static struct inode *jffs2_alloc_inode(struct super_block *sb)
{
        struct jffs2_inode_info *f;

        f = alloc_inode_sb(sb, jffs2_inode_cachep, GFP_KERNEL);
        if (!f)
                return NULL;
        return &f->vfs_inode;
}

static void jffs2_free_inode(struct inode *inode)
{
        struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);

        kfree(f->target);
        kmem_cache_free(jffs2_inode_cachep, f);
}

static void jffs2_i_init_once(void *foo)
{
        struct jffs2_inode_info *f = foo;

        mutex_init(&f->sem);
        f->target = NULL;
        inode_init_once(&f->vfs_inode);
}

static const char *jffs2_compr_name(unsigned int compr)
{
        switch (compr) {
        case JFFS2_COMPR_MODE_NONE:
                return "none";
#ifdef CONFIG_JFFS2_LZO
        case JFFS2_COMPR_MODE_FORCELZO:
                return "lzo";
#endif
#ifdef CONFIG_JFFS2_ZLIB
        case JFFS2_COMPR_MODE_FORCEZLIB:
                return "zlib";
#endif
        default:
                /* should never happen; programmer error */
                WARN_ON(1);
                return "";
        }
}

static int jffs2_show_options(struct seq_file *s, struct dentry *root)
{
        struct jffs2_sb_info *c = JFFS2_SB_INFO(root->d_sb);
        struct jffs2_mount_opts *opts = &c->mount_opts;

        if (opts->override_compr)
                seq_printf(s, ",compr=%s", jffs2_compr_name(opts->compr));
        if (opts->set_rp_size)
                seq_printf(s, ",rp_size=%u", opts->rp_size / 1024);

        return 0;
}

static int jffs2_sync_fs(struct super_block *sb, int wait)
{
        struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);

#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
        if (jffs2_is_writebuffered(c))
                cancel_delayed_work_sync(&c->wbuf_dwork);
#endif

        mutex_lock(&c->alloc_sem);
        jffs2_flush_wbuf_pad(c);
        mutex_unlock(&c->alloc_sem);
        return 0;
}

static struct inode *jffs2_nfs_get_inode(struct super_block *sb, uint64_t ino,
                                         uint32_t generation)
{
        /* We don't care about i_generation. We'll destroy the flash
           before we start re-using inode numbers anyway. And even
           if that wasn't true, we'd have other problems...*/
        return jffs2_iget(sb, ino);
}

static struct dentry *jffs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
                                         int fh_len, int fh_type)
{
        return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
                                    jffs2_nfs_get_inode);
}

static struct dentry *jffs2_fh_to_parent(struct super_block *sb, struct fid *fid,
                                         int fh_len, int fh_type)
{
        return generic_fh_to_parent(sb, fid, fh_len, fh_type,
                                    jffs2_nfs_get_inode);
}

static struct dentry *jffs2_get_parent(struct dentry *child)
{
        struct jffs2_inode_info *f;
        uint32_t pino;

        BUG_ON(!d_is_dir(child));

        f = JFFS2_INODE_INFO(d_inode(child));

        pino = f->inocache->pino_nlink;

        JFFS2_DEBUG("Parent of directory ino #%u is #%u\n",
                    f->inocache->ino, pino);

        return d_obtain_alias(jffs2_iget(child->d_sb, pino));
}

static const struct export_operations jffs2_export_ops = {
        .encode_fh = generic_encode_ino32_fh,
        .get_parent = jffs2_get_parent,
        .fh_to_dentry = jffs2_fh_to_dentry,
        .fh_to_parent = jffs2_fh_to_parent,
};

/*
 * JFFS2 mount options.
 *
 * Opt_source: The source device
 * Opt_override_compr: override default compressor
 * Opt_rp_size: size of reserved pool in KiB
 */
enum {
        Opt_override_compr,
        Opt_rp_size,
};

static const struct constant_table jffs2_param_compr[] = {
        {"none",        JFFS2_COMPR_MODE_NONE },
#ifdef CONFIG_JFFS2_LZO
        {"lzo",         JFFS2_COMPR_MODE_FORCELZO },
#endif
#ifdef CONFIG_JFFS2_ZLIB
        {"zlib",        JFFS2_COMPR_MODE_FORCEZLIB },
#endif
        {}
};

static const struct fs_parameter_spec jffs2_fs_parameters[] = {
        fsparam_enum    ("compr",       Opt_override_compr, jffs2_param_compr),
        fsparam_u32     ("rp_size",     Opt_rp_size),
        {}
};

static int jffs2_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
        struct fs_parse_result result;
        struct jffs2_sb_info *c = fc->s_fs_info;
        int opt;

        opt = fs_parse(fc, jffs2_fs_parameters, param, &result);
        if (opt < 0)
                return opt;

        switch (opt) {
        case Opt_override_compr:
                c->mount_opts.compr = result.uint_32;
                c->mount_opts.override_compr = true;
                break;
        case Opt_rp_size:
                if (result.uint_32 > UINT_MAX / 1024)
                        return invalf(fc, "jffs2: rp_size unrepresentable");
                c->mount_opts.rp_size = result.uint_32 * 1024;
                c->mount_opts.set_rp_size = true;
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static inline void jffs2_update_mount_opts(struct fs_context *fc)
{
        struct jffs2_sb_info *new_c = fc->s_fs_info;
        struct jffs2_sb_info *c = JFFS2_SB_INFO(fc->root->d_sb);

        mutex_lock(&c->alloc_sem);
        if (new_c->mount_opts.override_compr) {
                c->mount_opts.override_compr = new_c->mount_opts.override_compr;
                c->mount_opts.compr = new_c->mount_opts.compr;
        }
        if (new_c->mount_opts.set_rp_size) {
                c->mount_opts.set_rp_size = new_c->mount_opts.set_rp_size;
                c->mount_opts.rp_size = new_c->mount_opts.rp_size;
        }
        mutex_unlock(&c->alloc_sem);
}

static int jffs2_reconfigure(struct fs_context *fc)
{
        struct super_block *sb = fc->root->d_sb;

        sync_filesystem(sb);
        jffs2_update_mount_opts(fc);

        return jffs2_do_remount_fs(sb, fc);
}

static const struct super_operations jffs2_super_operations =
{
        .alloc_inode =  jffs2_alloc_inode,
        .free_inode =   jffs2_free_inode,
        .put_super =    jffs2_put_super,
        .statfs =       jffs2_statfs,
        .evict_inode =  jffs2_evict_inode,
        .dirty_inode =  jffs2_dirty_inode,
        .show_options = jffs2_show_options,
        .sync_fs =      jffs2_sync_fs,
};

/*
 * fill in the superblock
 */
static int jffs2_fill_super(struct super_block *sb, struct fs_context *fc)
{
        struct jffs2_sb_info *c = sb->s_fs_info;

        jffs2_dbg(1, "jffs2_get_sb_mtd():"
                  " New superblock for device %d (\"%s\")\n",
                  sb->s_mtd->index, sb->s_mtd->name);

        c->mtd = sb->s_mtd;
        c->os_priv = sb;

        if (c->mount_opts.rp_size > c->mtd->size)
                return invalf(fc, "jffs2: Too large reserve pool specified, max is %llu KB",
                              c->mtd->size / 1024);

        /* Initialize JFFS2 superblock locks, the further initialization will
         * be done later */
        mutex_init(&c->alloc_sem);
        mutex_init(&c->erase_free_sem);
        init_waitqueue_head(&c->erase_wait);
        init_waitqueue_head(&c->inocache_wq);
        spin_lock_init(&c->erase_completion_lock);
        spin_lock_init(&c->inocache_lock);

        sb->s_op = &jffs2_super_operations;
        sb->s_export_op = &jffs2_export_ops;
        sb->s_flags = sb->s_flags | SB_NOATIME;
        sb->s_xattr = jffs2_xattr_handlers;
#ifdef CONFIG_JFFS2_FS_POSIX_ACL
        sb->s_flags |= SB_POSIXACL;
#endif
        return jffs2_do_fill_super(sb, fc);
}

static int jffs2_get_tree(struct fs_context *fc)
{
        return get_tree_mtd(fc, jffs2_fill_super);
}

static void jffs2_free_fc(struct fs_context *fc)
{
        kfree(fc->s_fs_info);
}

static const struct fs_context_operations jffs2_context_ops = {
        .free           = jffs2_free_fc,
        .parse_param    = jffs2_parse_param,
        .get_tree       = jffs2_get_tree,
        .reconfigure    = jffs2_reconfigure,
};

static int jffs2_init_fs_context(struct fs_context *fc)
{
        struct jffs2_sb_info *ctx;

        ctx = kzalloc_obj(struct jffs2_sb_info);
        if (!ctx)
                return -ENOMEM;

        fc->s_fs_info = ctx;
        fc->ops = &jffs2_context_ops;
        return 0;
}

static void jffs2_put_super (struct super_block *sb)
{
        struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);

        jffs2_dbg(2, "%s()\n", __func__);

        mutex_lock(&c->alloc_sem);
        jffs2_flush_wbuf_pad(c);
        mutex_unlock(&c->alloc_sem);

        jffs2_sum_exit(c);

        jffs2_free_ino_caches(c);
        jffs2_free_raw_node_refs(c);
        kvfree(c->blocks);
        jffs2_flash_cleanup(c);
        kfree(c->inocache_list);
        jffs2_clear_xattr_subsystem(c);
        mtd_sync(c->mtd);
        jffs2_dbg(1, "%s(): returning\n", __func__);
}

static void jffs2_kill_sb(struct super_block *sb)
{
        struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
        if (c && !sb_rdonly(sb))
                jffs2_stop_garbage_collect_thread(c);
        kill_mtd_super(sb);
        kfree(c);
}

static struct file_system_type jffs2_fs_type = {
        .owner =        THIS_MODULE,
        .name =         "jffs2",
        .init_fs_context = jffs2_init_fs_context,
        .parameters =   jffs2_fs_parameters,
        .kill_sb =      jffs2_kill_sb,
};
MODULE_ALIAS_FS("jffs2");

static int __init init_jffs2_fs(void)
{
        int ret;

        /* Paranoia checks for on-medium structures. If we ask GCC
           to pack them with __attribute__((packed)) then it _also_
           assumes that they're not aligned -- so it emits crappy
           code on some architectures. Ideally we want an attribute
           which means just 'no padding', without the alignment
           thing. But GCC doesn't have that -- we have to just
           hope the structs are the right sizes, instead. */
        BUILD_BUG_ON(sizeof(struct jffs2_unknown_node) != 12);
        BUILD_BUG_ON(sizeof(struct jffs2_raw_dirent) != 40);
        BUILD_BUG_ON(sizeof(struct jffs2_raw_inode) != 68);
        BUILD_BUG_ON(sizeof(struct jffs2_raw_summary) != 32);

        pr_info("version 2.2."
#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
               " (NAND)"
#endif
#ifdef CONFIG_JFFS2_SUMMARY
               " (SUMMARY) "
#endif
               " © 2001-2006 Red Hat, Inc.\n");

        jffs2_inode_cachep = kmem_cache_create("jffs2_i",
                                             sizeof(struct jffs2_inode_info),
                                             0, (SLAB_RECLAIM_ACCOUNT|
                                                SLAB_ACCOUNT),
                                             jffs2_i_init_once);
        if (!jffs2_inode_cachep) {
                pr_err("error: Failed to initialise inode cache\n");
                return -ENOMEM;
        }
        ret = jffs2_compressors_init();
        if (ret) {
                pr_err("error: Failed to initialise compressors\n");
                goto out;
        }
        ret = jffs2_create_slab_caches();
        if (ret) {
                pr_err("error: Failed to initialise slab caches\n");
                goto out_compressors;
        }
        ret = register_filesystem(&jffs2_fs_type);
        if (ret) {
                pr_err("error: Failed to register filesystem\n");
                goto out_slab;
        }
        return 0;

 out_slab:
        jffs2_destroy_slab_caches();
 out_compressors:
        jffs2_compressors_exit();
 out:
        kmem_cache_destroy(jffs2_inode_cachep);
        return ret;
}

static void __exit exit_jffs2_fs(void)
{
        unregister_filesystem(&jffs2_fs_type);
        jffs2_destroy_slab_caches();
        jffs2_compressors_exit();

        /*
         * Make sure all delayed rcu free inodes are flushed before we
         * destroy cache.
         */
        rcu_barrier();
        kmem_cache_destroy(jffs2_inode_cachep);
}

module_init(init_jffs2_fs);
module_exit(exit_jffs2_fs);

MODULE_DESCRIPTION("The Journalling Flash File System, v2");
MODULE_AUTHOR("Red Hat, Inc.");
MODULE_LICENSE("GPL"); // Actually dual-licensed, but it doesn't matter for
                       // the sake of this tag. It's Free Software.