dir.c

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/*
 *  fs/bfs/dir.c
 *  BFS directory operations.
 *  Copyright (C) 1999,2000  Tigran Aivazian <[email protected]>
 *      Made endianness-clean by Andrew Stribblehill <[email protected]> 2005
 */

#include <linux/time.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/buffer_head.h>
#include <linux/sched.h>
#include "bfs.h"

#undef DEBUG

#ifdef DEBUG
#define dprintf(x...)   printf(x)
#else
#define dprintf(x...)
#endif

static int bfs_add_entry(struct inode *dir, const unsigned char *name,
                        int namelen, int ino);
static struct buffer_head *bfs_find_entry(struct inode *dir,
                const unsigned char *name, int namelen,
                struct bfs_dirent **res_dir);

static int bfs_readdir(struct file *f, void *dirent, filldir_t filldir)
{
    struct inode *dir = f->f_path.dentry->d_inode;
    struct buffer_head *bh;
    struct bfs_dirent *de;
    struct bfs_sb_info *info = BFS_SB(dir->i_sb);
    unsigned int offset;
    int block;

    mutex_lock(&info->bfs_lock);

    if (f->f_pos & (BFS_DIRENT_SIZE - 1)) {
        printf("Bad f_pos=%08lx for %s:%08lx\n",
                    (unsigned long)f->f_pos,
                    dir->i_sb->s_id, dir->i_ino);
        mutex_unlock(&info->bfs_lock);
        return -EBADF;
    }

    while (f->f_pos < dir->i_size) {
        offset = f->f_pos & (BFS_BSIZE - 1);
        block = BFS_I(dir)->i_sblock + (f->f_pos >> BFS_BSIZE_BITS);
        bh = sb_bread(dir->i_sb, block);
        if (!bh) {
            f->f_pos += BFS_BSIZE - offset;
            continue;
        }
        do {
            de = (struct bfs_dirent *)(bh->b_data + offset);
            if (de->ino) {
                int size = strnlen(de->name, BFS_NAMELEN);
                if (filldir(dirent, de->name, size, f->f_pos,
                        le16_to_cpu(de->ino),
                        DT_UNKNOWN) < 0) {
                    brelse(bh);
                    mutex_unlock(&info->bfs_lock);
                    return 0;
                }
            }
            offset += BFS_DIRENT_SIZE;
            f->f_pos += BFS_DIRENT_SIZE;
        } while ((offset < BFS_BSIZE) && (f->f_pos < dir->i_size));
        brelse(bh);
    }

    mutex_unlock(&info->bfs_lock);
    return 0;   
}

const struct file_operations bfs_dir_operations = {
    .read       = generic_read_dir,
    .readdir    = bfs_readdir,
    .fsync      = generic_file_fsync,
    .llseek     = generic_file_llseek,
};

extern void dump_imap(const char *, struct super_block *);

static int bfs_create(struct inode *dir, struct dentry *dentry, umode_t mode,
                        bool excl)
{
    int err;
    struct inode *inode;
    struct super_block *s = dir->i_sb;
    struct bfs_sb_info *info = BFS_SB(s);
    unsigned long ino;

    inode = new_inode(s);
    if (!inode)
        return -ENOSPC;
    mutex_lock(&info->bfs_lock);
    ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1);
    if (ino > info->si_lasti) {
        mutex_unlock(&info->bfs_lock);
        iput(inode);
        return -ENOSPC;
    }
    set_bit(ino, info->si_imap);
    info->si_freei--;
    inode_init_owner(inode, dir, mode);
    inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME_SEC;
    inode->i_blocks = 0;
    inode->i_op = &bfs_file_inops;
    inode->i_fop = &bfs_file_operations;
    inode->i_mapping->a_ops = &bfs_aops;
    inode->i_ino = ino;
    BFS_I(inode)->i_dsk_ino = ino;
    BFS_I(inode)->i_sblock = 0;
    BFS_I(inode)->i_eblock = 0;
    insert_inode_hash(inode);
        mark_inode_dirty(inode);
    dump_imap("create", s);

    err = bfs_add_entry(dir, dentry->d_name.name, dentry->d_name.len,
                            inode->i_ino);
    if (err) {
        inode_dec_link_count(inode);
        mutex_unlock(&info->bfs_lock);
        iput(inode);
        return err;
    }
    mutex_unlock(&info->bfs_lock);
    d_instantiate(dentry, inode);
    return 0;
}

static struct dentry *bfs_lookup(struct inode *dir, struct dentry *dentry,
                        unsigned int flags)
{
    struct inode *inode = NULL;
    struct buffer_head *bh;
    struct bfs_dirent *de;
    struct bfs_sb_info *info = BFS_SB(dir->i_sb);

    if (dentry->d_name.len > BFS_NAMELEN)
        return ERR_PTR(-ENAMETOOLONG);

    mutex_lock(&info->bfs_lock);
    bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
    if (bh) {
        unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
        brelse(bh);
        inode = bfs_iget(dir->i_sb, ino);
        if (IS_ERR(inode)) {
            mutex_unlock(&info->bfs_lock);
            return ERR_CAST(inode);
        }
    }
    mutex_unlock(&info->bfs_lock);
    d_add(dentry, inode);
    return NULL;
}

static int bfs_link(struct dentry *old, struct inode *dir,
                        struct dentry *new)
{
    struct inode *inode = old->d_inode;
    struct bfs_sb_info *info = BFS_SB(inode->i_sb);
    int err;

    mutex_lock(&info->bfs_lock);
    err = bfs_add_entry(dir, new->d_name.name, new->d_name.len,
                            inode->i_ino);
    if (err) {
        mutex_unlock(&info->bfs_lock);
        return err;
    }
    inc_nlink(inode);
    inode->i_ctime = CURRENT_TIME_SEC;
    mark_inode_dirty(inode);
    ihold(inode);
    d_instantiate(new, inode);
    mutex_unlock(&info->bfs_lock);
    return 0;
}

static int bfs_unlink(struct inode *dir, struct dentry *dentry)
{
    int error = -ENOENT;
    struct inode *inode = dentry->d_inode;
    struct buffer_head *bh;
    struct bfs_dirent *de;
    struct bfs_sb_info *info = BFS_SB(inode->i_sb);

    mutex_lock(&info->bfs_lock);
    bh = bfs_find_entry(dir, dentry->d_name.name, dentry->d_name.len, &de);
    if (!bh || (le16_to_cpu(de->ino) != inode->i_ino))
        goto out_brelse;

    if (!inode->i_nlink) {
        printf("unlinking non-existent file %s:%lu (nlink=%d)\n",
                    inode->i_sb->s_id, inode->i_ino,
                    inode->i_nlink);
        set_nlink(inode, 1);
    }
    de->ino = 0;
    mark_buffer_dirty_inode(bh, dir);
    dir->i_ctime = dir->i_mtime = CURRENT_TIME_SEC;
    mark_inode_dirty(dir);
    inode->i_ctime = dir->i_ctime;
    inode_dec_link_count(inode);
    error = 0;

out_brelse:
    brelse(bh);
    mutex_unlock(&info->bfs_lock);
    return error;
}

static int bfs_rename(struct inode *old_dir, struct dentry *old_dentry,
            struct inode *new_dir, struct dentry *new_dentry)
{
    struct inode *old_inode, *new_inode;
    struct buffer_head *old_bh, *new_bh;
    struct bfs_dirent *old_de, *new_de;
    struct bfs_sb_info *info;
    int error = -ENOENT;

    old_bh = new_bh = NULL;
    old_inode = old_dentry->d_inode;
    if (S_ISDIR(old_inode->i_mode))
        return -EINVAL;

    info = BFS_SB(old_inode->i_sb);

    mutex_lock(&info->bfs_lock);
    old_bh = bfs_find_entry(old_dir, 
                old_dentry->d_name.name, 
                old_dentry->d_name.len, &old_de);

    if (!old_bh || (le16_to_cpu(old_de->ino) != old_inode->i_ino))
        goto end_rename;

    error = -EPERM;
    new_inode = new_dentry->d_inode;
    new_bh = bfs_find_entry(new_dir, 
                new_dentry->d_name.name, 
                new_dentry->d_name.len, &new_de);

    if (new_bh && !new_inode) {
        brelse(new_bh);
        new_bh = NULL;
    }
    if (!new_bh) {
        error = bfs_add_entry(new_dir, 
                    new_dentry->d_name.name,
                    new_dentry->d_name.len,
                    old_inode->i_ino);
        if (error)
            goto end_rename;
    }
    old_de->ino = 0;
    old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC;
    mark_inode_dirty(old_dir);
    if (new_inode) {
        new_inode->i_ctime = CURRENT_TIME_SEC;
        inode_dec_link_count(new_inode);
    }
    mark_buffer_dirty_inode(old_bh, old_dir);
    error = 0;

end_rename:
    mutex_unlock(&info->bfs_lock);
    brelse(old_bh);
    brelse(new_bh);
    return error;
}

const struct inode_operations bfs_dir_inops = {
    .create         = bfs_create,
    .lookup         = bfs_lookup,
    .link           = bfs_link,
    .unlink         = bfs_unlink,
    .rename         = bfs_rename,
};

static int bfs_add_entry(struct inode *dir, const unsigned char *name,
                            int namelen, int ino)
{
    struct buffer_head *bh;
    struct bfs_dirent *de;
    int block, sblock, eblock, off, pos;
    int i;

    dprintf("name=%s, namelen=%d\n", name, namelen);

    if (!namelen)
        return -ENOENT;
    if (namelen > BFS_NAMELEN)
        return -ENAMETOOLONG;

    sblock = BFS_I(dir)->i_sblock;
    eblock = BFS_I(dir)->i_eblock;
    for (block = sblock; block <= eblock; block++) {
        bh = sb_bread(dir->i_sb, block);
        if (!bh)
            return -ENOSPC;
        for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) {
            de = (struct bfs_dirent *)(bh->b_data + off);
            if (!de->ino) {
                pos = (block - sblock) * BFS_BSIZE + off;
                if (pos >= dir->i_size) {
                    dir->i_size += BFS_DIRENT_SIZE;
                    dir->i_ctime = CURRENT_TIME_SEC;
                }
                dir->i_mtime = CURRENT_TIME_SEC;
                mark_inode_dirty(dir);
                de->ino = cpu_to_le16((u16)ino);
                for (i = 0; i < BFS_NAMELEN; i++)
                    de->name[i] =
                        (i < namelen) ? name[i] : 0;
                mark_buffer_dirty_inode(bh, dir);
                brelse(bh);
                return 0;
            }
        }
        brelse(bh);
    }
    return -ENOSPC;
}

static inline int bfs_namecmp(int len, const unsigned char *name,
                            const char *buffer)
{
    if ((len < BFS_NAMELEN) && buffer[len])
        return 0;
    return !memcmp(name, buffer, len);
}

static struct buffer_head *bfs_find_entry(struct inode *dir,
            const unsigned char *name, int namelen,
            struct bfs_dirent **res_dir)
{
    unsigned long block = 0, offset = 0;
    struct buffer_head *bh = NULL;
    struct bfs_dirent *de;

    *res_dir = NULL;
    if (namelen > BFS_NAMELEN)
        return NULL;

    while (block * BFS_BSIZE + offset < dir->i_size) {
        if (!bh) {
            bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
            if (!bh) {
                block++;
                continue;
            }
        }
        de = (struct bfs_dirent *)(bh->b_data + offset);
        offset += BFS_DIRENT_SIZE;
        if (le16_to_cpu(de->ino) &&
                bfs_namecmp(namelen, name, de->name)) {
            *res_dir = de;
            return bh;
        }
        if (offset < bh->b_size)
            continue;
        brelse(bh);
        bh = NULL;
        offset = 0;
        block++;
    }
    brelse(bh);
    return NULL;
}