super.c

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/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright © 2001-2007 Red Hat, Inc.
 *
 * Created by David Woodhouse <[email protected]>
 *
 * 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/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 = kmem_cache_alloc(jffs2_inode_cachep, GFP_KERNEL);
    if (!f)
        return NULL;
    return &f->vfs_inode;
}

static void jffs2_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    kmem_cache_free(jffs2_inode_cachep, JFFS2_INODE_INFO(inode));
}

static void jffs2_destroy_inode(struct inode *inode)
{
    call_rcu(&inode->i_rcu, jffs2_i_callback);
}

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

    mutex_init(&f->sem);
    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->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
    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(!S_ISDIR(child->d_inode->i_mode));

    f = JFFS2_INODE_INFO(child->d_inode);

    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_inode->i_sb, pino));
}

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

/*
 * JFFS2 mount options.
 *
 * Opt_override_compr: override default compressor
 * Opt_rp_size: size of reserved pool in KiB
 * Opt_err: just end of array marker
 */
enum {
    Opt_override_compr,
    Opt_rp_size,
    Opt_err,
};

static const match_table_t tokens = {
    {Opt_override_compr, "compr=%s"},
    {Opt_rp_size, "rp_size=%u"},
    {Opt_err, NULL},
};

static int jffs2_parse_options(struct jffs2_sb_info *c, char *data)
{
    substring_t args[MAX_OPT_ARGS];
    char *p, *name;
    unsigned int opt;

    if (!data)
        return 0;

    while ((p = strsep(&data, ","))) {
        int token;

        if (!*p)
            continue;

        token = match_token(p, tokens, args);
        switch (token) {
        case Opt_override_compr:
            name = match_strdup(&args[0]);

            if (!name)
                return -ENOMEM;
            if (!strcmp(name, "none"))
                c->mount_opts.compr = JFFS2_COMPR_MODE_NONE;
#ifdef CONFIG_JFFS2_LZO
            else if (!strcmp(name, "lzo"))
                c->mount_opts.compr = JFFS2_COMPR_MODE_FORCELZO;
#endif
#ifdef CONFIG_JFFS2_ZLIB
            else if (!strcmp(name, "zlib"))
                c->mount_opts.compr =
                        JFFS2_COMPR_MODE_FORCEZLIB;
#endif
            else {
                pr_err("Error: unknown compressor \"%s\"\n",
                       name);
                kfree(name);
                return -EINVAL;
            }
            kfree(name);
            c->mount_opts.override_compr = true;
            break;
        case Opt_rp_size:
            if (match_int(&args[0], &opt))
                return -EINVAL;
            opt *= 1024;
            if (opt > c->mtd->size) {
                pr_warn("Too large reserve pool specified, max "
                    "is %llu KB\n", c->mtd->size / 1024);
                return -EINVAL;
            }
            c->mount_opts.rp_size = opt;
            break;
        default:
            pr_err("Error: unrecognized mount option '%s' or missing value\n",
                   p);
            return -EINVAL;
        }
    }

    return 0;
}

static int jffs2_remount_fs(struct super_block *sb, int *flags, char *data)
{
    struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);
    int err;

    err = jffs2_parse_options(c, data);
    if (err)
        return -EINVAL;

    return jffs2_do_remount_fs(sb, flags, data);
}

static const struct super_operations jffs2_super_operations =
{
    .alloc_inode =  jffs2_alloc_inode,
    .destroy_inode =jffs2_destroy_inode,
    .put_super =    jffs2_put_super,
    .statfs =   jffs2_statfs,
    .remount_fs =   jffs2_remount_fs,
    .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, void *data, int silent)
{
    struct jffs2_sb_info *c;
    int ret;

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

    c = kzalloc(sizeof(*c), GFP_KERNEL);
    if (!c)
        return -ENOMEM;

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

    ret = jffs2_parse_options(c, data);
    if (ret) {
        kfree(c);
        return -EINVAL;
    }

    /* 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 | MS_NOATIME;
    sb->s_xattr = jffs2_xattr_handlers;
#ifdef CONFIG_JFFS2_FS_POSIX_ACL
    sb->s_flags |= MS_POSIXACL;
#endif
    ret = jffs2_do_fill_super(sb, data, silent);
    return ret;
}

static struct dentry *jffs2_mount(struct file_system_type *fs_type,
            int flags, const char *dev_name,
            void *data)
{
    return mount_mtd(fs_type, flags, dev_name, data, jffs2_fill_super);
}

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);
    if (jffs2_blocks_use_vmalloc(c))
        vfree(c->blocks);
    else
        kfree(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 (!(sb->s_flags & MS_RDONLY))
        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",
    .mount =    jffs2_mount,
    .kill_sb =  jffs2_kill_sb,
};

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_MEM_SPREAD),
                         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.