inode.c

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/*
 * Optimized MPEG FS - inode and super operations.
 * Copyright (C) 2006 Bob Copeland <[email protected]>
 * Released under GPL v2.
 */
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/vfs.h>
#include <linux/parser.h>
#include <linux/buffer_head.h>
#include <linux/vmalloc.h>
#include <linux/writeback.h>
#include <linux/crc-itu-t.h>
#include "omfs.h"

MODULE_AUTHOR("Bob Copeland <[email protected]>");
MODULE_DESCRIPTION("OMFS (ReplayTV/Karma) Filesystem for Linux");
MODULE_LICENSE("GPL");

struct buffer_head *omfs_bread(struct super_block *sb, sector_t block)
{
    struct omfs_sb_info *sbi = OMFS_SB(sb);
    if (block >= sbi->s_num_blocks)
        return NULL;

    return sb_bread(sb, clus_to_blk(sbi, block));
}

struct inode *omfs_new_inode(struct inode *dir, umode_t mode)
{
    struct inode *inode;
    u64 new_block;
    int err;
    int len;
    struct omfs_sb_info *sbi = OMFS_SB(dir->i_sb);

    inode = new_inode(dir->i_sb);
    if (!inode)
        return ERR_PTR(-ENOMEM);

    err = omfs_allocate_range(dir->i_sb, sbi->s_mirrors, sbi->s_mirrors,
            &new_block, &len);
    if (err)
        goto fail;

    inode->i_ino = new_block;
    inode_init_owner(inode, NULL, mode);
    inode->i_mapping->a_ops = &omfs_aops;

    inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
    switch (mode & S_IFMT) {
    case S_IFDIR:
        inode->i_op = &omfs_dir_inops;
        inode->i_fop = &omfs_dir_operations;
        inode->i_size = sbi->s_sys_blocksize;
        inc_nlink(inode);
        break;
    case S_IFREG:
        inode->i_op = &omfs_file_inops;
        inode->i_fop = &omfs_file_operations;
        inode->i_size = 0;
        break;
    }

    insert_inode_hash(inode);
    mark_inode_dirty(inode);
    return inode;
fail:
    make_bad_inode(inode);
    iput(inode);
    return ERR_PTR(err);
}

/*
 * Update the header checksums for a dirty inode based on its contents.
 * Caller is expected to hold the buffer head underlying oi and mark it
 * dirty.
 */
static void omfs_update_checksums(struct omfs_inode *oi)
{
    int xor, i, ofs = 0, count;
    u16 crc = 0;
    unsigned char *ptr = (unsigned char *) oi;

    count = be32_to_cpu(oi->i_head.h_body_size);
    ofs = sizeof(struct omfs_header);

    crc = crc_itu_t(crc, ptr + ofs, count);
    oi->i_head.h_crc = cpu_to_be16(crc);

    xor = ptr[0];
    for (i = 1; i < OMFS_XOR_COUNT; i++)
        xor ^= ptr[i];

    oi->i_head.h_check_xor = xor;
}

static int __omfs_write_inode(struct inode *inode, int wait)
{
    struct omfs_inode *oi;
    struct omfs_sb_info *sbi = OMFS_SB(inode->i_sb);
    struct buffer_head *bh, *bh2;
    u64 ctime;
    int i;
    int ret = -EIO;
    int sync_failed = 0;

    /* get current inode since we may have written sibling ptrs etc. */
    bh = omfs_bread(inode->i_sb, inode->i_ino);
    if (!bh)
        goto out;

    oi = (struct omfs_inode *) bh->b_data;

    oi->i_head.h_self = cpu_to_be64(inode->i_ino);
    if (S_ISDIR(inode->i_mode))
        oi->i_type = OMFS_DIR;
    else if (S_ISREG(inode->i_mode))
        oi->i_type = OMFS_FILE;
    else {
        printk(KERN_WARNING "omfs: unknown file type: %d\n",
            inode->i_mode);
        goto out_brelse;
    }

    oi->i_head.h_body_size = cpu_to_be32(sbi->s_sys_blocksize -
        sizeof(struct omfs_header));
    oi->i_head.h_version = 1;
    oi->i_head.h_type = OMFS_INODE_NORMAL;
    oi->i_head.h_magic = OMFS_IMAGIC;
    oi->i_size = cpu_to_be64(inode->i_size);

    ctime = inode->i_ctime.tv_sec * 1000LL +
        ((inode->i_ctime.tv_nsec + 999)/1000);
    oi->i_ctime = cpu_to_be64(ctime);

    omfs_update_checksums(oi);

    mark_buffer_dirty(bh);
    if (wait) {
        sync_dirty_buffer(bh);
        if (buffer_req(bh) && !buffer_uptodate(bh))
            sync_failed = 1;
    }

    /* if mirroring writes, copy to next fsblock */
    for (i = 1; i < sbi->s_mirrors; i++) {
        bh2 = omfs_bread(inode->i_sb, inode->i_ino + i);
        if (!bh2)
            goto out_brelse;

        memcpy(bh2->b_data, bh->b_data, bh->b_size);
        mark_buffer_dirty(bh2);
        if (wait) {
            sync_dirty_buffer(bh2);
            if (buffer_req(bh2) && !buffer_uptodate(bh2))
                sync_failed = 1;
        }
        brelse(bh2);
    }
    ret = (sync_failed) ? -EIO : 0;
out_brelse:
    brelse(bh);
out:
    return ret;
}

static int omfs_write_inode(struct inode *inode, struct writeback_control *wbc)
{
    return __omfs_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
}

int omfs_sync_inode(struct inode *inode)
{
    return __omfs_write_inode(inode, 1);
}

/*
 * called when an entry is deleted, need to clear the bits in the
 * bitmaps.
 */
static void omfs_evict_inode(struct inode *inode)
{
    truncate_inode_pages(&inode->i_data, 0);
    clear_inode(inode);

    if (inode->i_nlink)
        return;

    if (S_ISREG(inode->i_mode)) {
        inode->i_size = 0;
        omfs_shrink_inode(inode);
    }

    omfs_clear_range(inode->i_sb, inode->i_ino, 2);
}

struct inode *omfs_iget(struct super_block *sb, ino_t ino)
{
    struct omfs_sb_info *sbi = OMFS_SB(sb);
    struct omfs_inode *oi;
    struct buffer_head *bh;
    u64 ctime;
    unsigned long nsecs;
    struct inode *inode;

    inode = iget_locked(sb, ino);
    if (!inode)
        return ERR_PTR(-ENOMEM);
    if (!(inode->i_state & I_NEW))
        return inode;

    bh = omfs_bread(inode->i_sb, ino);
    if (!bh)
        goto iget_failed;

    oi = (struct omfs_inode *)bh->b_data;

    /* check self */
    if (ino != be64_to_cpu(oi->i_head.h_self))
        goto fail_bh;

    inode->i_uid = sbi->s_uid;
    inode->i_gid = sbi->s_gid;

    ctime = be64_to_cpu(oi->i_ctime);
    nsecs = do_div(ctime, 1000) * 1000L;

    inode->i_atime.tv_sec = ctime;
    inode->i_mtime.tv_sec = ctime;
    inode->i_ctime.tv_sec = ctime;
    inode->i_atime.tv_nsec = nsecs;
    inode->i_mtime.tv_nsec = nsecs;
    inode->i_ctime.tv_nsec = nsecs;

    inode->i_mapping->a_ops = &omfs_aops;

    switch (oi->i_type) {
    case OMFS_DIR:
        inode->i_mode = S_IFDIR | (S_IRWXUGO & ~sbi->s_dmask);
        inode->i_op = &omfs_dir_inops;
        inode->i_fop = &omfs_dir_operations;
        inode->i_size = sbi->s_sys_blocksize;
        inc_nlink(inode);
        break;
    case OMFS_FILE:
        inode->i_mode = S_IFREG | (S_IRWXUGO & ~sbi->s_fmask);
        inode->i_fop = &omfs_file_operations;
        inode->i_size = be64_to_cpu(oi->i_size);
        break;
    }
    brelse(bh);
    unlock_new_inode(inode);
    return inode;
fail_bh:
    brelse(bh);
iget_failed:
    iget_failed(inode);
    return ERR_PTR(-EIO);
}

static void omfs_put_super(struct super_block *sb)
{
    struct omfs_sb_info *sbi = OMFS_SB(sb);
    kfree(sbi->s_imap);
    kfree(sbi);
    sb->s_fs_info = NULL;
}

static int omfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
    struct super_block *s = dentry->d_sb;
    struct omfs_sb_info *sbi = OMFS_SB(s);
    u64 id = huge_encode_dev(s->s_bdev->bd_dev);

    buf->f_type = OMFS_MAGIC;
    buf->f_bsize = sbi->s_blocksize;
    buf->f_blocks = sbi->s_num_blocks;
    buf->f_files = sbi->s_num_blocks;
    buf->f_namelen = OMFS_NAMELEN;
    buf->f_fsid.val[0] = (u32)id;
    buf->f_fsid.val[1] = (u32)(id >> 32);

    buf->f_bfree = buf->f_bavail = buf->f_ffree =
        omfs_count_free(s);

    return 0;
}

static const struct super_operations omfs_sops = {
    .write_inode    = omfs_write_inode,
    .evict_inode    = omfs_evict_inode,
    .put_super  = omfs_put_super,
    .statfs     = omfs_statfs,
    .show_options   = generic_show_options,
};

/*
 * For Rio Karma, there is an on-disk free bitmap whose location is
 * stored in the root block.  For ReplayTV, there is no such free bitmap
 * so we have to walk the tree.  Both inodes and file data are allocated
 * from the same map.  This array can be big (300k) so we allocate
 * in units of the blocksize.
 */
static int omfs_get_imap(struct super_block *sb)
{
    int bitmap_size;
    int array_size;
    int count;
    struct omfs_sb_info *sbi = OMFS_SB(sb);
    struct buffer_head *bh;
    unsigned long **ptr;
    sector_t block;

    bitmap_size = DIV_ROUND_UP(sbi->s_num_blocks, 8);
    array_size = DIV_ROUND_UP(bitmap_size, sb->s_blocksize);

    if (sbi->s_bitmap_ino == ~0ULL)
        goto out;

    sbi->s_imap_size = array_size;
    sbi->s_imap = kzalloc(array_size * sizeof(unsigned long *), GFP_KERNEL);
    if (!sbi->s_imap)
        goto nomem;

    block = clus_to_blk(sbi, sbi->s_bitmap_ino);
    if (block >= sbi->s_num_blocks)
        goto nomem;

    ptr = sbi->s_imap;
    for (count = bitmap_size; count > 0; count -= sb->s_blocksize) {
        bh = sb_bread(sb, block++);
        if (!bh)
            goto nomem_free;
        *ptr = kmalloc(sb->s_blocksize, GFP_KERNEL);
        if (!*ptr) {
            brelse(bh);
            goto nomem_free;
        }
        memcpy(*ptr, bh->b_data, sb->s_blocksize);
        if (count < sb->s_blocksize)
            memset((void *)*ptr + count, 0xff,
                sb->s_blocksize - count);
        brelse(bh);
        ptr++;
    }
out:
    return 0;

nomem_free:
    for (count = 0; count < array_size; count++)
        kfree(sbi->s_imap[count]);

    kfree(sbi->s_imap);
nomem:
    sbi->s_imap = NULL;
    sbi->s_imap_size = 0;
    return -ENOMEM;
}

enum {
    Opt_uid, Opt_gid, Opt_umask, Opt_dmask, Opt_fmask
};

static const match_table_t tokens = {
    {Opt_uid, "uid=%u"},
    {Opt_gid, "gid=%u"},
    {Opt_umask, "umask=%o"},
    {Opt_dmask, "dmask=%o"},
    {Opt_fmask, "fmask=%o"},
};

static int parse_options(char *options, struct omfs_sb_info *sbi)
{
    char *p;
    substring_t args[MAX_OPT_ARGS];
    int option;

    if (!options)
        return 1;

    while ((p = strsep(&options, ",")) != NULL) {
        int token;
        if (!*p)
            continue;

        token = match_token(p, tokens, args);
        switch (token) {
        case Opt_uid:
            if (match_int(&args[0], &option))
                return 0;
            sbi->s_uid = make_kuid(current_user_ns(), option);
            if (!uid_valid(sbi->s_uid))
                return 0;
            break;
        case Opt_gid:
            if (match_int(&args[0], &option))
                return 0;
            sbi->s_gid = make_kgid(current_user_ns(), option);
            if (!gid_valid(sbi->s_gid))
                return 0;
            break;
        case Opt_umask:
            if (match_octal(&args[0], &option))
                return 0;
            sbi->s_fmask = sbi->s_dmask = option;
            break;
        case Opt_dmask:
            if (match_octal(&args[0], &option))
                return 0;
            sbi->s_dmask = option;
            break;
        case Opt_fmask:
            if (match_octal(&args[0], &option))
                return 0;
            sbi->s_fmask = option;
            break;
        default:
            return 0;
        }
    }
    return 1;
}

static int omfs_fill_super(struct super_block *sb, void *data, int silent)
{
    struct buffer_head *bh, *bh2;
    struct omfs_super_block *omfs_sb;
    struct omfs_root_block *omfs_rb;
    struct omfs_sb_info *sbi;
    struct inode *root;
    int ret = -EINVAL;

    save_mount_options(sb, (char *) data);

    sbi = kzalloc(sizeof(struct omfs_sb_info), GFP_KERNEL);
    if (!sbi)
        return -ENOMEM;

    sb->s_fs_info = sbi;

    sbi->s_uid = current_uid();
    sbi->s_gid = current_gid();
    sbi->s_dmask = sbi->s_fmask = current_umask();

    if (!parse_options((char *) data, sbi))
        goto end;

    sb->s_maxbytes = 0xffffffff;

    sb_set_blocksize(sb, 0x200);

    bh = sb_bread(sb, 0);
    if (!bh)
        goto end;

    omfs_sb = (struct omfs_super_block *)bh->b_data;

    if (omfs_sb->s_magic != cpu_to_be32(OMFS_MAGIC)) {
        if (!silent)
            printk(KERN_ERR "omfs: Invalid superblock (%x)\n",
                   omfs_sb->s_magic);
        goto out_brelse_bh;
    }
    sb->s_magic = OMFS_MAGIC;

    sbi->s_num_blocks = be64_to_cpu(omfs_sb->s_num_blocks);
    sbi->s_blocksize = be32_to_cpu(omfs_sb->s_blocksize);
    sbi->s_mirrors = be32_to_cpu(omfs_sb->s_mirrors);
    sbi->s_root_ino = be64_to_cpu(omfs_sb->s_root_block);
    sbi->s_sys_blocksize = be32_to_cpu(omfs_sb->s_sys_blocksize);
    mutex_init(&sbi->s_bitmap_lock);

    if (sbi->s_sys_blocksize > PAGE_SIZE) {
        printk(KERN_ERR "omfs: sysblock size (%d) is out of range\n",
            sbi->s_sys_blocksize);
        goto out_brelse_bh;
    }

    if (sbi->s_blocksize < sbi->s_sys_blocksize ||
        sbi->s_blocksize > OMFS_MAX_BLOCK_SIZE) {
        printk(KERN_ERR "omfs: block size (%d) is out of range\n",
            sbi->s_blocksize);
        goto out_brelse_bh;
    }

    /*
     * Use sys_blocksize as the fs block since it is smaller than a
     * page while the fs blocksize can be larger.
     */
    sb_set_blocksize(sb, sbi->s_sys_blocksize);

    /*
     * ...and the difference goes into a shift.  sys_blocksize is always
     * a power of two factor of blocksize.
     */
    sbi->s_block_shift = get_bitmask_order(sbi->s_blocksize) -
        get_bitmask_order(sbi->s_sys_blocksize);

    bh2 = omfs_bread(sb, be64_to_cpu(omfs_sb->s_root_block));
    if (!bh2)
        goto out_brelse_bh;

    omfs_rb = (struct omfs_root_block *)bh2->b_data;

    sbi->s_bitmap_ino = be64_to_cpu(omfs_rb->r_bitmap);
    sbi->s_clustersize = be32_to_cpu(omfs_rb->r_clustersize);

    if (sbi->s_num_blocks != be64_to_cpu(omfs_rb->r_num_blocks)) {
        printk(KERN_ERR "omfs: block count discrepancy between "
            "super and root blocks (%llx, %llx)\n",
            (unsigned long long)sbi->s_num_blocks,
            (unsigned long long)be64_to_cpu(omfs_rb->r_num_blocks));
        goto out_brelse_bh2;
    }

    if (sbi->s_bitmap_ino != ~0ULL &&
        sbi->s_bitmap_ino > sbi->s_num_blocks) {
        printk(KERN_ERR "omfs: free space bitmap location is corrupt "
            "(%llx, total blocks %llx)\n",
            (unsigned long long) sbi->s_bitmap_ino,
            (unsigned long long) sbi->s_num_blocks);
        goto out_brelse_bh2;
    }
    if (sbi->s_clustersize < 1 ||
        sbi->s_clustersize > OMFS_MAX_CLUSTER_SIZE) {
        printk(KERN_ERR "omfs: cluster size out of range (%d)",
            sbi->s_clustersize);
        goto out_brelse_bh2;
    }

    ret = omfs_get_imap(sb);
    if (ret)
        goto out_brelse_bh2;

    sb->s_op = &omfs_sops;

    root = omfs_iget(sb, be64_to_cpu(omfs_rb->r_root_dir));
    if (IS_ERR(root)) {
        ret = PTR_ERR(root);
        goto out_brelse_bh2;
    }

    sb->s_root = d_make_root(root);
    if (!sb->s_root)
        goto out_brelse_bh2;
    printk(KERN_DEBUG "omfs: Mounted volume %s\n", omfs_rb->r_name);

    ret = 0;
out_brelse_bh2:
    brelse(bh2);
out_brelse_bh:
    brelse(bh);
end:
    if (ret)
        kfree(sbi);
    return ret;
}

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

static struct file_system_type omfs_fs_type = {
    .owner = THIS_MODULE,
    .name = "omfs",
    .mount = omfs_mount,
    .kill_sb = kill_block_super,
    .fs_flags = FS_REQUIRES_DEV,
};

static int __init init_omfs_fs(void)
{
    return register_filesystem(&omfs_fs_type);
}

static void __exit exit_omfs_fs(void)
{
    unregister_filesystem(&omfs_fs_type);
}

module_init(init_omfs_fs);
module_exit(exit_omfs_fs);