super.c

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/*
 * super.c
 *
 * Copyright (c) 1999 Al Smith
 *
 * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
 */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/exportfs.h>
#include <linux/slab.h>
#include <linux/buffer_head.h>
#include <linux/vfs.h>

#include "efs.h"
#include <linux/efs_vh.h>
#include <linux/efs_fs_sb.h>

static int efs_statfs(struct dentry *dentry, struct kstatfs *buf);
static int efs_fill_super(struct super_block *s, void *d, int silent);

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

static struct file_system_type efs_fs_type = {
    .owner      = THIS_MODULE,
    .name       = "efs",
    .mount      = efs_mount,
    .kill_sb    = kill_block_super,
    .fs_flags   = FS_REQUIRES_DEV,
};

static struct pt_types sgi_pt_types[] = {
    {0x00,      "SGI vh"},
    {0x01,      "SGI trkrepl"},
    {0x02,      "SGI secrepl"},
    {0x03,      "SGI raw"},
    {0x04,      "SGI bsd"},
    {SGI_SYSV,  "SGI sysv"},
    {0x06,      "SGI vol"},
    {SGI_EFS,   "SGI efs"},
    {0x08,      "SGI lv"},
    {0x09,      "SGI rlv"},
    {0x0A,      "SGI xfs"},
    {0x0B,      "SGI xfslog"},
    {0x0C,      "SGI xlv"},
    {0x82,      "Linux swap"},
    {0x83,      "Linux native"},
    {0,     NULL}
};


static struct kmem_cache * efs_inode_cachep;

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

static void efs_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    kmem_cache_free(efs_inode_cachep, INODE_INFO(inode));
}

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

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

    inode_init_once(&ei->vfs_inode);
}

static int init_inodecache(void)
{
    efs_inode_cachep = kmem_cache_create("efs_inode_cache",
                sizeof(struct efs_inode_info),
                0, SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD,
                init_once);
    if (efs_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(efs_inode_cachep);
}

static void efs_put_super(struct super_block *s)
{
    kfree(s->s_fs_info);
    s->s_fs_info = NULL;
}

static int efs_remount(struct super_block *sb, int *flags, char *data)
{
    *flags |= MS_RDONLY;
    return 0;
}

static const struct super_operations efs_superblock_operations = {
    .alloc_inode    = efs_alloc_inode,
    .destroy_inode  = efs_destroy_inode,
    .put_super  = efs_put_super,
    .statfs     = efs_statfs,
    .remount_fs = efs_remount,
};

static const struct export_operations efs_export_ops = {
    .fh_to_dentry   = efs_fh_to_dentry,
    .fh_to_parent   = efs_fh_to_parent,
    .get_parent = efs_get_parent,
};

static int __init init_efs_fs(void) {
    int err;
    printk("EFS: "EFS_VERSION" - http://aeschi.ch.eu.org/efs/\n");
    err = init_inodecache();
    if (err)
        goto out1;
    err = register_filesystem(&efs_fs_type);
    if (err)
        goto out;
    return 0;
out:
    destroy_inodecache();
out1:
    return err;
}

static void __exit exit_efs_fs(void) {
    unregister_filesystem(&efs_fs_type);
    destroy_inodecache();
}

module_init(init_efs_fs)
module_exit(exit_efs_fs)

static efs_block_t efs_validate_vh(struct volume_header *vh) {
    int     i;
    __be32      cs, *ui;
    int     csum;
    efs_block_t sblock = 0; /* shuts up gcc */
    struct pt_types *pt_entry;
    int     pt_type, slice = -1;

    if (be32_to_cpu(vh->vh_magic) != VHMAGIC) {
        /*
         * assume that we're dealing with a partition and allow
         * read_super() to try and detect a valid superblock
         * on the next block.
         */
        return 0;
    }

    ui = ((__be32 *) (vh + 1)) - 1;
    for(csum = 0; ui >= ((__be32 *) vh);) {
        cs = *ui--;
        csum += be32_to_cpu(cs);
    }
    if (csum) {
        printk(KERN_INFO "EFS: SGI disklabel: checksum bad, label corrupted\n");
        return 0;
    }

#ifdef DEBUG
    printk(KERN_DEBUG "EFS: bf: \"%16s\"\n", vh->vh_bootfile);

    for(i = 0; i < NVDIR; i++) {
        int j;
        char    name[VDNAMESIZE+1];

        for(j = 0; j < VDNAMESIZE; j++) {
            name[j] = vh->vh_vd[i].vd_name[j];
        }
        name[j] = (char) 0;

        if (name[0]) {
            printk(KERN_DEBUG "EFS: vh: %8s block: 0x%08x size: 0x%08x\n",
                name,
                (int) be32_to_cpu(vh->vh_vd[i].vd_lbn),
                (int) be32_to_cpu(vh->vh_vd[i].vd_nbytes));
        }
    }
#endif

    for(i = 0; i < NPARTAB; i++) {
        pt_type = (int) be32_to_cpu(vh->vh_pt[i].pt_type);
        for(pt_entry = sgi_pt_types; pt_entry->pt_name; pt_entry++) {
            if (pt_type == pt_entry->pt_type) break;
        }
#ifdef DEBUG
        if (be32_to_cpu(vh->vh_pt[i].pt_nblks)) {
            printk(KERN_DEBUG "EFS: pt %2d: start: %08d size: %08d type: 0x%02x (%s)\n",
                i,
                (int) be32_to_cpu(vh->vh_pt[i].pt_firstlbn),
                (int) be32_to_cpu(vh->vh_pt[i].pt_nblks),
                pt_type,
                (pt_entry->pt_name) ? pt_entry->pt_name : "unknown");
        }
#endif
        if (IS_EFS(pt_type)) {
            sblock = be32_to_cpu(vh->vh_pt[i].pt_firstlbn);
            slice = i;
        }
    }

    if (slice == -1) {
        printk(KERN_NOTICE "EFS: partition table contained no EFS partitions\n");
#ifdef DEBUG
    } else {
        printk(KERN_INFO "EFS: using slice %d (type %s, offset 0x%x)\n",
            slice,
            (pt_entry->pt_name) ? pt_entry->pt_name : "unknown",
            sblock);
#endif
    }
    return sblock;
}

static int efs_validate_super(struct efs_sb_info *sb, struct efs_super *super) {

    if (!IS_EFS_MAGIC(be32_to_cpu(super->fs_magic)))
        return -1;

    sb->fs_magic     = be32_to_cpu(super->fs_magic);
    sb->total_blocks = be32_to_cpu(super->fs_size);
    sb->first_block  = be32_to_cpu(super->fs_firstcg);
    sb->group_size   = be32_to_cpu(super->fs_cgfsize);
    sb->data_free    = be32_to_cpu(super->fs_tfree);
    sb->inode_free   = be32_to_cpu(super->fs_tinode);
    sb->inode_blocks = be16_to_cpu(super->fs_cgisize);
    sb->total_groups = be16_to_cpu(super->fs_ncg);
    
    return 0;    
}

static int efs_fill_super(struct super_block *s, void *d, int silent)
{
    struct efs_sb_info *sb;
    struct buffer_head *bh;
    struct inode *root;
    int ret = -EINVAL;

    sb = kzalloc(sizeof(struct efs_sb_info), GFP_KERNEL);
    if (!sb)
        return -ENOMEM;
    s->s_fs_info = sb;
 
    s->s_magic      = EFS_SUPER_MAGIC;
    if (!sb_set_blocksize(s, EFS_BLOCKSIZE)) {
        printk(KERN_ERR "EFS: device does not support %d byte blocks\n",
            EFS_BLOCKSIZE);
        goto out_no_fs_ul;
    }
  
    /* read the vh (volume header) block */
    bh = sb_bread(s, 0);

    if (!bh) {
        printk(KERN_ERR "EFS: cannot read volume header\n");
        goto out_no_fs_ul;
    }

    /*
     * if this returns zero then we didn't find any partition table.
     * this isn't (yet) an error - just assume for the moment that
     * the device is valid and go on to search for a superblock.
     */
    sb->fs_start = efs_validate_vh((struct volume_header *) bh->b_data);
    brelse(bh);

    if (sb->fs_start == -1) {
        goto out_no_fs_ul;
    }

    bh = sb_bread(s, sb->fs_start + EFS_SUPER);
    if (!bh) {
        printk(KERN_ERR "EFS: cannot read superblock\n");
        goto out_no_fs_ul;
    }
        
    if (efs_validate_super(sb, (struct efs_super *) bh->b_data)) {
#ifdef DEBUG
        printk(KERN_WARNING "EFS: invalid superblock at block %u\n", sb->fs_start + EFS_SUPER);
#endif
        brelse(bh);
        goto out_no_fs_ul;
    }
    brelse(bh);

    if (!(s->s_flags & MS_RDONLY)) {
#ifdef DEBUG
        printk(KERN_INFO "EFS: forcing read-only mode\n");
#endif
        s->s_flags |= MS_RDONLY;
    }
    s->s_op   = &efs_superblock_operations;
    s->s_export_op = &efs_export_ops;
    root = efs_iget(s, EFS_ROOTINODE);
    if (IS_ERR(root)) {
        printk(KERN_ERR "EFS: get root inode failed\n");
        ret = PTR_ERR(root);
        goto out_no_fs;
    }

    s->s_root = d_make_root(root);
    if (!(s->s_root)) {
        printk(KERN_ERR "EFS: get root dentry failed\n");
        ret = -ENOMEM;
        goto out_no_fs;
    }

    return 0;

out_no_fs_ul:
out_no_fs:
    s->s_fs_info = NULL;
    kfree(sb);
    return ret;
}

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

    buf->f_type    = EFS_SUPER_MAGIC;   /* efs magic number */
    buf->f_bsize   = EFS_BLOCKSIZE;     /* blocksize */
    buf->f_blocks  = sbi->total_groups *    /* total data blocks */
            (sbi->group_size - sbi->inode_blocks);
    buf->f_bfree   = sbi->data_free;    /* free data blocks */
    buf->f_bavail  = sbi->data_free;    /* free blocks for non-root */
    buf->f_files   = sbi->total_groups *    /* total inodes */
            sbi->inode_blocks *
            (EFS_BLOCKSIZE / sizeof(struct efs_dinode));
    buf->f_ffree   = sbi->inode_free;   /* free inodes */
    buf->f_fsid.val[0] = (u32)id;
    buf->f_fsid.val[1] = (u32)(id >> 32);
    buf->f_namelen = EFS_MAXNAMELEN;    /* max filename length */

    return 0;
}