super.c

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/*
 *  linux/fs/adfs/super.c
 *
 *  Copyright (C) 1997-1999 Russell King
 *
 * 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.
 */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/buffer_head.h>
#include <linux/parser.h>
#include <linux/mount.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/statfs.h>
#include <linux/user_namespace.h>
#include "adfs.h"
#include "dir_f.h"
#include "dir_fplus.h"

#define ADFS_DEFAULT_OWNER_MASK S_IRWXU
#define ADFS_DEFAULT_OTHER_MASK (S_IRWXG | S_IRWXO)

void __adfs_error(struct super_block *sb, const char *function, const char *fmt, ...)
{
    char error_buf[128];
    va_list args;

    va_start(args, fmt);
    vsnprintf(error_buf, sizeof(error_buf), fmt, args);
    va_end(args);

    printk(KERN_CRIT "ADFS-fs error (device %s)%s%s: %s\n",
        sb->s_id, function ? ": " : "",
        function ? function : "", error_buf);
}

static int adfs_checkdiscrecord(struct adfs_discrecord *dr)
{
    int i;

    /* sector size must be 256, 512 or 1024 bytes */
    if (dr->log2secsize != 8 &&
        dr->log2secsize != 9 &&
        dr->log2secsize != 10)
        return 1;

    /* idlen must be at least log2secsize + 3 */
    if (dr->idlen < dr->log2secsize + 3)
        return 1;

    /* we cannot have such a large disc that we
     * are unable to represent sector offsets in
     * 32 bits.  This works out at 2.0 TB.
     */
    if (le32_to_cpu(dr->disc_size_high) >> dr->log2secsize)
        return 1;

    /* idlen must be no greater than 19 v2 [1.0] */
    if (dr->idlen > 19)
        return 1;

    /* reserved bytes should be zero */
    for (i = 0; i < sizeof(dr->unused52); i++)
        if (dr->unused52[i] != 0)
            return 1;

    return 0;
}

static unsigned char adfs_calczonecheck(struct super_block *sb, unsigned char *map)
{
    unsigned int v0, v1, v2, v3;
    int i;

    v0 = v1 = v2 = v3 = 0;
    for (i = sb->s_blocksize - 4; i; i -= 4) {
        v0 += map[i]     + (v3 >> 8);
        v3 &= 0xff;
        v1 += map[i + 1] + (v0 >> 8);
        v0 &= 0xff;
        v2 += map[i + 2] + (v1 >> 8);
        v1 &= 0xff;
        v3 += map[i + 3] + (v2 >> 8);
        v2 &= 0xff;
    }
    v0 +=           v3 >> 8;
    v1 += map[1] + (v0 >> 8);
    v2 += map[2] + (v1 >> 8);
    v3 += map[3] + (v2 >> 8);

    return v0 ^ v1 ^ v2 ^ v3;
}

static int adfs_checkmap(struct super_block *sb, struct adfs_discmap *dm)
{
    unsigned char crosscheck = 0, zonecheck = 1;
    int i;

    for (i = 0; i < ADFS_SB(sb)->s_map_size; i++) {
        unsigned char *map;

        map = dm[i].dm_bh->b_data;

        if (adfs_calczonecheck(sb, map) != map[0]) {
            adfs_error(sb, "zone %d fails zonecheck", i);
            zonecheck = 0;
        }
        crosscheck ^= map[3];
    }
    if (crosscheck != 0xff)
        adfs_error(sb, "crosscheck != 0xff");
    return crosscheck == 0xff && zonecheck;
}

static void adfs_put_super(struct super_block *sb)
{
    int i;
    struct adfs_sb_info *asb = ADFS_SB(sb);

    for (i = 0; i < asb->s_map_size; i++)
        brelse(asb->s_map[i].dm_bh);
    kfree(asb->s_map);
    kfree(asb);
    sb->s_fs_info = NULL;
}

static int adfs_show_options(struct seq_file *seq, struct dentry *root)
{
    struct adfs_sb_info *asb = ADFS_SB(root->d_sb);

    if (!uid_eq(asb->s_uid, GLOBAL_ROOT_UID))
        seq_printf(seq, ",uid=%u", from_kuid_munged(&init_user_ns, asb->s_uid));
    if (!gid_eq(asb->s_gid, GLOBAL_ROOT_GID))
        seq_printf(seq, ",gid=%u", from_kgid_munged(&init_user_ns, asb->s_gid));
    if (asb->s_owner_mask != ADFS_DEFAULT_OWNER_MASK)
        seq_printf(seq, ",ownmask=%o", asb->s_owner_mask);
    if (asb->s_other_mask != ADFS_DEFAULT_OTHER_MASK)
        seq_printf(seq, ",othmask=%o", asb->s_other_mask);
    if (asb->s_ftsuffix != 0)
        seq_printf(seq, ",ftsuffix=%u", asb->s_ftsuffix);

    return 0;
}

enum {Opt_uid, Opt_gid, Opt_ownmask, Opt_othmask, Opt_ftsuffix, Opt_err};

static const match_table_t tokens = {
    {Opt_uid, "uid=%u"},
    {Opt_gid, "gid=%u"},
    {Opt_ownmask, "ownmask=%o"},
    {Opt_othmask, "othmask=%o"},
    {Opt_ftsuffix, "ftsuffix=%u"},
    {Opt_err, NULL}
};

static int parse_options(struct super_block *sb, char *options)
{
    char *p;
    struct adfs_sb_info *asb = ADFS_SB(sb);
    int option;

    if (!options)
        return 0;

    while ((p = strsep(&options, ",")) != NULL) {
        substring_t args[MAX_OPT_ARGS];
        int token;
        if (!*p)
            continue;

        token = match_token(p, tokens, args);
        switch (token) {
        case Opt_uid:
            if (match_int(args, &option))
                return -EINVAL;
            asb->s_uid = make_kuid(current_user_ns(), option);
            if (!uid_valid(asb->s_uid))
                return -EINVAL;
            break;
        case Opt_gid:
            if (match_int(args, &option))
                return -EINVAL;
            asb->s_gid = make_kgid(current_user_ns(), option);
            if (!gid_valid(asb->s_gid))
                return -EINVAL;
            break;
        case Opt_ownmask:
            if (match_octal(args, &option))
                return -EINVAL;
            asb->s_owner_mask = option;
            break;
        case Opt_othmask:
            if (match_octal(args, &option))
                return -EINVAL;
            asb->s_other_mask = option;
            break;
        case Opt_ftsuffix:
            if (match_int(args, &option))
                return -EINVAL;
            asb->s_ftsuffix = option;
            break;
        default:
            printk("ADFS-fs: unrecognised mount option \"%s\" "
                    "or missing value\n", p);
            return -EINVAL;
        }
    }
    return 0;
}

static int adfs_remount(struct super_block *sb, int *flags, char *data)
{
    *flags |= MS_NODIRATIME;
    return parse_options(sb, data);
}

static int adfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
    struct super_block *sb = dentry->d_sb;
    struct adfs_sb_info *sbi = ADFS_SB(sb);
    u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

    buf->f_type    = ADFS_SUPER_MAGIC;
    buf->f_namelen = sbi->s_namelen;
    buf->f_bsize   = sb->s_blocksize;
    buf->f_blocks  = sbi->s_size;
    buf->f_files   = sbi->s_ids_per_zone * sbi->s_map_size;
    buf->f_bavail  =
    buf->f_bfree   = adfs_map_free(sb);
    buf->f_ffree   = (long)(buf->f_bfree * buf->f_files) / (long)buf->f_blocks;
    buf->f_fsid.val[0] = (u32)id;
    buf->f_fsid.val[1] = (u32)(id >> 32);

    return 0;
}

static struct kmem_cache *adfs_inode_cachep;

static struct inode *adfs_alloc_inode(struct super_block *sb)
{
    struct adfs_inode_info *ei;
    ei = (struct adfs_inode_info *)kmem_cache_alloc(adfs_inode_cachep, GFP_KERNEL);
    if (!ei)
        return NULL;
    return &ei->vfs_inode;
}

static void adfs_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    kmem_cache_free(adfs_inode_cachep, ADFS_I(inode));
}

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

static void init_once(void *foo)
{
    struct adfs_inode_info *ei = (struct adfs_inode_info *) foo;

    inode_init_once(&ei->vfs_inode);
}

static int init_inodecache(void)
{
    adfs_inode_cachep = kmem_cache_create("adfs_inode_cache",
                         sizeof(struct adfs_inode_info),
                         0, (SLAB_RECLAIM_ACCOUNT|
                        SLAB_MEM_SPREAD),
                         init_once);
    if (adfs_inode_cachep == NULL)
        return -ENOMEM;
    return 0;
}

static void destroy_inodecache(void)
{
    /*
     * Make sure all delayed rcu free inodes are flushed before we
     * destroy cache.
     */
    rcu_barrier();
    kmem_cache_destroy(adfs_inode_cachep);
}

static const struct super_operations adfs_sops = {
    .alloc_inode    = adfs_alloc_inode,
    .destroy_inode  = adfs_destroy_inode,
    .write_inode    = adfs_write_inode,
    .put_super  = adfs_put_super,
    .statfs     = adfs_statfs,
    .remount_fs = adfs_remount,
    .show_options   = adfs_show_options,
};

static struct adfs_discmap *adfs_read_map(struct super_block *sb, struct adfs_discrecord *dr)
{
    struct adfs_discmap *dm;
    unsigned int map_addr, zone_size, nzones;
    int i, zone;
    struct adfs_sb_info *asb = ADFS_SB(sb);

    nzones    = asb->s_map_size;
    zone_size = (8 << dr->log2secsize) - le16_to_cpu(dr->zone_spare);
    map_addr  = (nzones >> 1) * zone_size -
             ((nzones > 1) ? ADFS_DR_SIZE_BITS : 0);
    map_addr  = signed_asl(map_addr, asb->s_map2blk);

    asb->s_ids_per_zone = zone_size / (asb->s_idlen + 1);

    dm = kmalloc(nzones * sizeof(*dm), GFP_KERNEL);
    if (dm == NULL) {
        adfs_error(sb, "not enough memory");
        return NULL;
    }

    for (zone = 0; zone < nzones; zone++, map_addr++) {
        dm[zone].dm_startbit = 0;
        dm[zone].dm_endbit   = zone_size;
        dm[zone].dm_startblk = zone * zone_size - ADFS_DR_SIZE_BITS;
        dm[zone].dm_bh       = sb_bread(sb, map_addr);

        if (!dm[zone].dm_bh) {
            adfs_error(sb, "unable to read map");
            goto error_free;
        }
    }

    /* adjust the limits for the first and last map zones */
    i = zone - 1;
    dm[0].dm_startblk = 0;
    dm[0].dm_startbit = ADFS_DR_SIZE_BITS;
    dm[i].dm_endbit   = (le32_to_cpu(dr->disc_size_high) << (32 - dr->log2bpmb)) +
                (le32_to_cpu(dr->disc_size) >> dr->log2bpmb) +
                (ADFS_DR_SIZE_BITS - i * zone_size);

    if (adfs_checkmap(sb, dm))
        return dm;

    adfs_error(sb, "map corrupted");

error_free:
    while (--zone >= 0)
        brelse(dm[zone].dm_bh);

    kfree(dm);
    return NULL;
}

static inline unsigned long adfs_discsize(struct adfs_discrecord *dr, int block_bits)
{
    unsigned long discsize;

    discsize  = le32_to_cpu(dr->disc_size_high) << (32 - block_bits);
    discsize |= le32_to_cpu(dr->disc_size) >> block_bits;

    return discsize;
}

static int adfs_fill_super(struct super_block *sb, void *data, int silent)
{
    struct adfs_discrecord *dr;
    struct buffer_head *bh;
    struct object_info root_obj;
    unsigned char *b_data;
    struct adfs_sb_info *asb;
    struct inode *root;

    sb->s_flags |= MS_NODIRATIME;

    asb = kzalloc(sizeof(*asb), GFP_KERNEL);
    if (!asb)
        return -ENOMEM;
    sb->s_fs_info = asb;

    /* set default options */
    asb->s_uid = GLOBAL_ROOT_UID;
    asb->s_gid = GLOBAL_ROOT_GID;
    asb->s_owner_mask = ADFS_DEFAULT_OWNER_MASK;
    asb->s_other_mask = ADFS_DEFAULT_OTHER_MASK;
    asb->s_ftsuffix = 0;

    if (parse_options(sb, data))
        goto error;

    sb_set_blocksize(sb, BLOCK_SIZE);
    if (!(bh = sb_bread(sb, ADFS_DISCRECORD / BLOCK_SIZE))) {
        adfs_error(sb, "unable to read superblock");
        goto error;
    }

    b_data = bh->b_data + (ADFS_DISCRECORD % BLOCK_SIZE);

    if (adfs_checkbblk(b_data)) {
        if (!silent)
            printk("VFS: Can't find an adfs filesystem on dev "
                "%s.\n", sb->s_id);
        goto error_free_bh;
    }

    dr = (struct adfs_discrecord *)(b_data + ADFS_DR_OFFSET);

    /*
     * Do some sanity checks on the ADFS disc record
     */
    if (adfs_checkdiscrecord(dr)) {
        if (!silent)
            printk("VPS: Can't find an adfs filesystem on dev "
                "%s.\n", sb->s_id);
        goto error_free_bh;
    }

    brelse(bh);
    if (sb_set_blocksize(sb, 1 << dr->log2secsize)) {
        bh = sb_bread(sb, ADFS_DISCRECORD / sb->s_blocksize);
        if (!bh) {
            adfs_error(sb, "couldn't read superblock on "
                "2nd try.");
            goto error;
        }
        b_data = bh->b_data + (ADFS_DISCRECORD % sb->s_blocksize);
        if (adfs_checkbblk(b_data)) {
            adfs_error(sb, "disc record mismatch, very weird!");
            goto error_free_bh;
        }
        dr = (struct adfs_discrecord *)(b_data + ADFS_DR_OFFSET);
    } else {
        if (!silent)
            printk(KERN_ERR "VFS: Unsupported blocksize on dev "
                "%s.\n", sb->s_id);
        goto error;
    }

    /*
     * blocksize on this device should now be set to the ADFS log2secsize
     */

    sb->s_magic     = ADFS_SUPER_MAGIC;
    asb->s_idlen        = dr->idlen;
    asb->s_map_size     = dr->nzones | (dr->nzones_high << 8);
    asb->s_map2blk      = dr->log2bpmb - dr->log2secsize;
    asb->s_size         = adfs_discsize(dr, sb->s_blocksize_bits);
    asb->s_version      = dr->format_version;
    asb->s_log2sharesize    = dr->log2sharesize;
    
    asb->s_map = adfs_read_map(sb, dr);
    if (!asb->s_map)
        goto error_free_bh;

    brelse(bh);

    /*
     * set up enough so that we can read an inode
     */
    sb->s_op = &adfs_sops;

    dr = (struct adfs_discrecord *)(asb->s_map[0].dm_bh->b_data + 4);

    root_obj.parent_id = root_obj.file_id = le32_to_cpu(dr->root);
    root_obj.name_len  = 0;
    /* Set root object date as 01 Jan 1987 00:00:00 */
    root_obj.loadaddr  = 0xfff0003f;
    root_obj.execaddr  = 0xec22c000;
    root_obj.size      = ADFS_NEWDIR_SIZE;
    root_obj.attr      = ADFS_NDA_DIRECTORY   | ADFS_NDA_OWNER_READ |
                 ADFS_NDA_OWNER_WRITE | ADFS_NDA_PUBLIC_READ;
    root_obj.filetype  = -1;

    /*
     * If this is a F+ disk with variable length directories,
     * get the root_size from the disc record.
     */
    if (asb->s_version) {
        root_obj.size = le32_to_cpu(dr->root_size);
        asb->s_dir     = &adfs_fplus_dir_ops;
        asb->s_namelen = ADFS_FPLUS_NAME_LEN;
    } else {
        asb->s_dir     = &adfs_f_dir_ops;
        asb->s_namelen = ADFS_F_NAME_LEN;
    }
    /*
     * ,xyz hex filetype suffix may be added by driver
     * to files that have valid RISC OS filetype
     */
    if (asb->s_ftsuffix)
        asb->s_namelen += 4;

    sb->s_d_op = &adfs_dentry_operations;
    root = adfs_iget(sb, &root_obj);
    sb->s_root = d_make_root(root);
    if (!sb->s_root) {
        int i;
        for (i = 0; i < asb->s_map_size; i++)
            brelse(asb->s_map[i].dm_bh);
        kfree(asb->s_map);
        adfs_error(sb, "get root inode failed\n");
        goto error;
    }
    return 0;

error_free_bh:
    brelse(bh);
error:
    sb->s_fs_info = NULL;
    kfree(asb);
    return -EINVAL;
}

static struct dentry *adfs_mount(struct file_system_type *fs_type,
    int flags, const char *dev_name, void *data)
{
    return mount_bdev(fs_type, flags, dev_name, data, adfs_fill_super);
}

static struct file_system_type adfs_fs_type = {
    .owner      = THIS_MODULE,
    .name       = "adfs",
    .mount      = adfs_mount,
    .kill_sb    = kill_block_super,
    .fs_flags   = FS_REQUIRES_DEV,
};

static int __init init_adfs_fs(void)
{
    int err = init_inodecache();
    if (err)
        goto out1;
    err = register_filesystem(&adfs_fs_type);
    if (err)
        goto out;
    return 0;
out:
    destroy_inodecache();
out1:
    return err;
}

static void __exit exit_adfs_fs(void)
{
    unregister_filesystem(&adfs_fs_type);
    destroy_inodecache();
}

module_init(init_adfs_fs)
module_exit(exit_adfs_fs)
MODULE_LICENSE("GPL");