inode.c

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/*
 * QNX4 file system, Linux implementation.
 *
 * Version : 0.2.1
 *
 * Using parts of the xiafs filesystem.
 *
 * History :
 *
 * 01-06-1998 by Richard Frowijn : first release.
 * 20-06-1998 by Frank Denis : Linux 2.1.99+ support, boot signature, misc.
 * 30-06-1998 by Frank Denis : first step to write inodes.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/highuid.h>
#include <linux/pagemap.h>
#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include <linux/statfs.h>
#include "qnx4.h"

#define QNX4_VERSION  4
#define QNX4_BMNAME   ".bitmap"

static const struct super_operations qnx4_sops;

static void qnx4_put_super(struct super_block *sb);
static struct inode *qnx4_alloc_inode(struct super_block *sb);
static void qnx4_destroy_inode(struct inode *inode);
static int qnx4_remount(struct super_block *sb, int *flags, char *data);
static int qnx4_statfs(struct dentry *, struct kstatfs *);

static const struct super_operations qnx4_sops =
{
    .alloc_inode    = qnx4_alloc_inode,
    .destroy_inode  = qnx4_destroy_inode,
    .put_super  = qnx4_put_super,
    .statfs     = qnx4_statfs,
    .remount_fs = qnx4_remount,
};

static int qnx4_remount(struct super_block *sb, int *flags, char *data)
{
    struct qnx4_sb_info *qs;

    qs = qnx4_sb(sb);
    qs->Version = QNX4_VERSION;
    *flags |= MS_RDONLY;
    return 0;
}

static int qnx4_get_block( struct inode *inode, sector_t iblock, struct buffer_head *bh, int create )
{
    unsigned long phys;

    QNX4DEBUG((KERN_INFO "qnx4: qnx4_get_block inode=[%ld] iblock=[%ld]\n",inode->i_ino,iblock));

    phys = qnx4_block_map( inode, iblock );
    if ( phys ) {
        // logical block is before EOF
        map_bh(bh, inode->i_sb, phys);
    }
    return 0;
}

static inline u32 try_extent(qnx4_xtnt_t *extent, u32 *offset)
{
    u32 size = le32_to_cpu(extent->xtnt_size);
    if (*offset < size)
        return le32_to_cpu(extent->xtnt_blk) + *offset - 1;
    *offset -= size;
    return 0;
}

unsigned long qnx4_block_map( struct inode *inode, long iblock )
{
    int ix;
    long i_xblk;
    struct buffer_head *bh = NULL;
    struct qnx4_xblk *xblk = NULL;
    struct qnx4_inode_entry *qnx4_inode = qnx4_raw_inode(inode);
    u16 nxtnt = le16_to_cpu(qnx4_inode->di_num_xtnts);
    u32 offset = iblock;
    u32 block = try_extent(&qnx4_inode->di_first_xtnt, &offset);

    if (block) {
        // iblock is in the first extent. This is easy.
    } else {
        // iblock is beyond first extent. We have to follow the extent chain.
        i_xblk = le32_to_cpu(qnx4_inode->di_xblk);
        ix = 0;
        while ( --nxtnt > 0 ) {
            if ( ix == 0 ) {
                // read next xtnt block.
                bh = sb_bread(inode->i_sb, i_xblk - 1);
                if ( !bh ) {
                    QNX4DEBUG((KERN_ERR "qnx4: I/O error reading xtnt block [%ld])\n", i_xblk - 1));
                    return -EIO;
                }
                xblk = (struct qnx4_xblk*)bh->b_data;
                if ( memcmp( xblk->xblk_signature, "IamXblk", 7 ) ) {
                    QNX4DEBUG((KERN_ERR "qnx4: block at %ld is not a valid xtnt\n", qnx4_inode->i_xblk));
                    return -EIO;
                }
            }
            block = try_extent(&xblk->xblk_xtnts[ix], &offset);
            if (block) {
                // got it!
                break;
            }
            if ( ++ix >= xblk->xblk_num_xtnts ) {
                i_xblk = le32_to_cpu(xblk->xblk_next_xblk);
                ix = 0;
                brelse( bh );
                bh = NULL;
            }
        }
        if ( bh )
            brelse( bh );
    }

    QNX4DEBUG((KERN_INFO "qnx4: mapping block %ld of inode %ld = %ld\n",iblock,inode->i_ino,block));
    return block;
}

static int qnx4_statfs(struct dentry *dentry, struct kstatfs *buf)
{
    struct super_block *sb = dentry->d_sb;
    u64 id = huge_encode_dev(sb->s_bdev->bd_dev);

    buf->f_type    = sb->s_magic;
    buf->f_bsize   = sb->s_blocksize;
    buf->f_blocks  = le32_to_cpu(qnx4_sb(sb)->BitMap->di_size) * 8;
    buf->f_bfree   = qnx4_count_free_blocks(sb);
    buf->f_bavail  = buf->f_bfree;
    buf->f_namelen = QNX4_NAME_MAX;
    buf->f_fsid.val[0] = (u32)id;
    buf->f_fsid.val[1] = (u32)(id >> 32);

    return 0;
}

/*
 * Check the root directory of the filesystem to make sure
 * it really _is_ a qnx4 filesystem, and to check the size
 * of the directory entry.
 */
static const char *qnx4_checkroot(struct super_block *sb)
{
    struct buffer_head *bh;
    struct qnx4_inode_entry *rootdir;
    int rd, rl;
    int i, j;

    if (*(qnx4_sb(sb)->sb->RootDir.di_fname) != '/')
        return "no qnx4 filesystem (no root dir).";
    QNX4DEBUG((KERN_NOTICE "QNX4 filesystem found on dev %s.\n", sb->s_id));
    rd = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_blk) - 1;
    rl = le32_to_cpu(qnx4_sb(sb)->sb->RootDir.di_first_xtnt.xtnt_size);
    for (j = 0; j < rl; j++) {
        bh = sb_bread(sb, rd + j);  /* root dir, first block */
        if (bh == NULL)
            return "unable to read root entry.";
        rootdir = (struct qnx4_inode_entry *) bh->b_data;
        for (i = 0; i < QNX4_INODES_PER_BLOCK; i++, rootdir++) {
            QNX4DEBUG((KERN_INFO "rootdir entry found : [%s]\n", rootdir->di_fname));
            if (strcmp(rootdir->di_fname, QNX4_BMNAME) != 0)
                continue;
            qnx4_sb(sb)->BitMap = kmemdup(rootdir,
                              sizeof(struct qnx4_inode_entry),
                              GFP_KERNEL);
            brelse(bh);
            if (!qnx4_sb(sb)->BitMap)
                return "not enough memory for bitmap inode";
            /* keep bitmap inode known */
            return NULL;
        }
        brelse(bh);
    }
    return "bitmap file not found.";
}

static int qnx4_fill_super(struct super_block *s, void *data, int silent)
{
    struct buffer_head *bh;
    struct inode *root;
    const char *errmsg;
    struct qnx4_sb_info *qs;
    int ret = -EINVAL;

    qs = kzalloc(sizeof(struct qnx4_sb_info), GFP_KERNEL);
    if (!qs)
        return -ENOMEM;
    s->s_fs_info = qs;

    sb_set_blocksize(s, QNX4_BLOCK_SIZE);

    /* Check the superblock signature. Since the qnx4 code is
       dangerous, we should leave as quickly as possible
       if we don't belong here... */
    bh = sb_bread(s, 1);
    if (!bh) {
        printk(KERN_ERR "qnx4: unable to read the superblock\n");
        goto outnobh;
    }
    if ( le32_to_cpup((__le32*) bh->b_data) != QNX4_SUPER_MAGIC ) {
        if (!silent)
            printk(KERN_ERR "qnx4: wrong fsid in superblock.\n");
        goto out;
    }
    s->s_op = &qnx4_sops;
    s->s_magic = QNX4_SUPER_MAGIC;
    s->s_flags |= MS_RDONLY;    /* Yup, read-only yet */
    qnx4_sb(s)->sb_buf = bh;
    qnx4_sb(s)->sb = (struct qnx4_super_block *) bh->b_data;


    /* check before allocating dentries, inodes, .. */
    errmsg = qnx4_checkroot(s);
    if (errmsg != NULL) {
        if (!silent)
            printk(KERN_ERR "qnx4: %s\n", errmsg);
        goto out;
    }

    /* does root not have inode number QNX4_ROOT_INO ?? */
    root = qnx4_iget(s, QNX4_ROOT_INO * QNX4_INODES_PER_BLOCK);
    if (IS_ERR(root)) {
        printk(KERN_ERR "qnx4: get inode failed\n");
        ret = PTR_ERR(root);
        goto outb;
    }

    ret = -ENOMEM;
    s->s_root = d_make_root(root);
    if (s->s_root == NULL)
        goto outb;

    brelse(bh);
    return 0;

      outb:
    kfree(qs->BitMap);
      out:
    brelse(bh);
      outnobh:
    kfree(qs);
    s->s_fs_info = NULL;
    return ret;
}

static void qnx4_put_super(struct super_block *sb)
{
    struct qnx4_sb_info *qs = qnx4_sb(sb);
    kfree( qs->BitMap );
    kfree( qs );
    sb->s_fs_info = NULL;
    return;
}

static int qnx4_readpage(struct file *file, struct page *page)
{
    return block_read_full_page(page,qnx4_get_block);
}

static sector_t qnx4_bmap(struct address_space *mapping, sector_t block)
{
    return generic_block_bmap(mapping,block,qnx4_get_block);
}
static const struct address_space_operations qnx4_aops = {
    .readpage   = qnx4_readpage,
    .bmap       = qnx4_bmap
};

struct inode *qnx4_iget(struct super_block *sb, unsigned long ino)
{
    struct buffer_head *bh;
    struct qnx4_inode_entry *raw_inode;
    int block;
    struct qnx4_inode_entry *qnx4_inode;
    struct inode *inode;

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

    qnx4_inode = qnx4_raw_inode(inode);
    inode->i_mode = 0;

    QNX4DEBUG((KERN_INFO "reading inode : [%d]\n", ino));
    if (!ino) {
        printk(KERN_ERR "qnx4: bad inode number on dev %s: %lu is "
                "out of range\n",
               sb->s_id, ino);
        iget_failed(inode);
        return ERR_PTR(-EIO);
    }
    block = ino / QNX4_INODES_PER_BLOCK;

    if (!(bh = sb_bread(sb, block))) {
        printk(KERN_ERR "qnx4: major problem: unable to read inode from dev "
               "%s\n", sb->s_id);
        iget_failed(inode);
        return ERR_PTR(-EIO);
    }
    raw_inode = ((struct qnx4_inode_entry *) bh->b_data) +
        (ino % QNX4_INODES_PER_BLOCK);

    inode->i_mode    = le16_to_cpu(raw_inode->di_mode);
    i_uid_write(inode, (uid_t)le16_to_cpu(raw_inode->di_uid));
    i_gid_write(inode, (gid_t)le16_to_cpu(raw_inode->di_gid));
    set_nlink(inode, le16_to_cpu(raw_inode->di_nlink));
    inode->i_size    = le32_to_cpu(raw_inode->di_size);
    inode->i_mtime.tv_sec   = le32_to_cpu(raw_inode->di_mtime);
    inode->i_mtime.tv_nsec = 0;
    inode->i_atime.tv_sec   = le32_to_cpu(raw_inode->di_atime);
    inode->i_atime.tv_nsec = 0;
    inode->i_ctime.tv_sec   = le32_to_cpu(raw_inode->di_ctime);
    inode->i_ctime.tv_nsec = 0;
    inode->i_blocks  = le32_to_cpu(raw_inode->di_first_xtnt.xtnt_size);

    memcpy(qnx4_inode, raw_inode, QNX4_DIR_ENTRY_SIZE);
    if (S_ISREG(inode->i_mode)) {
        inode->i_fop = &generic_ro_fops;
        inode->i_mapping->a_ops = &qnx4_aops;
        qnx4_i(inode)->mmu_private = inode->i_size;
    } else if (S_ISDIR(inode->i_mode)) {
        inode->i_op = &qnx4_dir_inode_operations;
        inode->i_fop = &qnx4_dir_operations;
    } else if (S_ISLNK(inode->i_mode)) {
        inode->i_op = &page_symlink_inode_operations;
        inode->i_mapping->a_ops = &qnx4_aops;
        qnx4_i(inode)->mmu_private = inode->i_size;
    } else {
        printk(KERN_ERR "qnx4: bad inode %lu on dev %s\n",
            ino, sb->s_id);
        iget_failed(inode);
        brelse(bh);
        return ERR_PTR(-EIO);
    }
    brelse(bh);
    unlock_new_inode(inode);
    return inode;
}

static struct kmem_cache *qnx4_inode_cachep;

static struct inode *qnx4_alloc_inode(struct super_block *sb)
{
    struct qnx4_inode_info *ei;
    ei = kmem_cache_alloc(qnx4_inode_cachep, GFP_KERNEL);
    if (!ei)
        return NULL;
    return &ei->vfs_inode;
}

static void qnx4_i_callback(struct rcu_head *head)
{
    struct inode *inode = container_of(head, struct inode, i_rcu);
    kmem_cache_free(qnx4_inode_cachep, qnx4_i(inode));
}

static void qnx4_destroy_inode(struct inode *inode)
{
    call_rcu(&inode->i_rcu, qnx4_i_callback);
}

static void init_once(void *foo)
{
    struct qnx4_inode_info *ei = (struct qnx4_inode_info *) foo;

    inode_init_once(&ei->vfs_inode);
}

static int init_inodecache(void)
{
    qnx4_inode_cachep = kmem_cache_create("qnx4_inode_cache",
                         sizeof(struct qnx4_inode_info),
                         0, (SLAB_RECLAIM_ACCOUNT|
                        SLAB_MEM_SPREAD),
                         init_once);
    if (qnx4_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(qnx4_inode_cachep);
}

static struct dentry *qnx4_mount(struct file_system_type *fs_type,
    int flags, const char *dev_name, void *data)
{
    return mount_bdev(fs_type, flags, dev_name, data, qnx4_fill_super);
}

static struct file_system_type qnx4_fs_type = {
    .owner      = THIS_MODULE,
    .name       = "qnx4",
    .mount      = qnx4_mount,
    .kill_sb    = kill_block_super,
    .fs_flags   = FS_REQUIRES_DEV,
};

static int __init init_qnx4_fs(void)
{
    int err;

    err = init_inodecache();
    if (err)
        return err;

    err = register_filesystem(&qnx4_fs_type);
    if (err) {
        destroy_inodecache();
        return err;
    }

    printk(KERN_INFO "QNX4 filesystem 0.2.3 registered.\n");
    return 0;
}

static void __exit exit_qnx4_fs(void)
{
    unregister_filesystem(&qnx4_fs_type);
    destroy_inodecache();
}

module_init(init_qnx4_fs)
module_exit(exit_qnx4_fs)
MODULE_LICENSE("GPL");