root/fs/bfs/dir.c

DEFINITIONS

1. bfs_readdir
2. bfs_create
3. bfs_lookup
4. bfs_link
5. bfs_unlink
6. bfs_rename
7. bfs_add_entry
8. bfs_namecmp
9. bfs_find_entry

/*
 *      fs/bfs/dir.c
 *      BFS directory operations.
 *      Copyright (C) 1999,2000  Tigran Aivazian <tigran@veritas.com>
 *      Made endianness-clean by Andrew Stribblehill <ads@wompom.org> 2005
 */

#include <linux/time.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/smp_lock.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          = file_fsync,
};

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

static int bfs_create(struct inode *dir, struct dentry *dentry, int mode,
                                                struct nameidata *nd)
{
        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);
        if (ino > info->si_lasti) {
                mutex_unlock(&info->bfs_lock);
                iput(inode);
                return -ENOSPC;
        }
        set_bit(ino, info->si_imap);
        info->si_freei--;
        inode->i_uid = current->fsuid;
        inode->i_gid = (dir->i_mode & S_ISGID) ? dir->i_gid : current->fsgid;
        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_mode = mode;
        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,
                                                struct nameidata *nd)
{
        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);
        atomic_inc(&inode->i_count);
        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);
                inode->i_nlink = 1;
        }
        de->ino = 0;
        mark_buffer_dirty(bh);
        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(old_bh);
        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(bh);
                                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;
}