namei.c

Linux内核源代码 为压缩文件 是<<Linux内核>>一书中的源代码

	struct super_block * sb;
	struct inode * inode;
	struct buffer_head * bh, * dir_block;
	struct ufs_dir_entry * de;
	int err;
	unsigned flags, swab;
	
	sb = dir->i_sb;
	flags = sb->u.ufs_sb.s_flags;
	swab = sb->u.ufs_sb.s_swab;

	err = -EMLINK;
	if (dir->i_nlink >= UFS_LINK_MAX)
		goto out;
	err = -EIO;
	inode = ufs_new_inode (dir, S_IFDIR, &err);
	if (!inode)
		goto out;

	inode->i_op = &ufs_dir_inode_operations;
	inode->i_fop = &ufs_dir_operations;
	inode->i_size = UFS_SECTOR_SIZE;
	dir_block = ufs_bread (inode, 0, 1, &err);
	if (!dir_block) {
		inode->i_nlink--; /* is this nlink == 0? */
		mark_inode_dirty(inode);
		iput (inode);
		return err;
	}
	inode->i_blocks = sb->s_blocksize / UFS_SECTOR_SIZE;
	de = (struct ufs_dir_entry *) dir_block->b_data;
	de->d_ino = SWAB32(inode->i_ino);
	ufs_set_de_type (de, inode->i_mode);
	ufs_set_de_namlen(de,1);
	de->d_reclen = SWAB16(UFS_DIR_REC_LEN(1));
	strcpy (de->d_name, ".");
	de = (struct ufs_dir_entry *) ((char *) de + SWAB16(de->d_reclen));
	de->d_ino = SWAB32(dir->i_ino);
	ufs_set_de_type (de, dir->i_mode);
	de->d_reclen = SWAB16(UFS_SECTOR_SIZE - UFS_DIR_REC_LEN(1));
	ufs_set_de_namlen(de,2);
	strcpy (de->d_name, "..");
	inode->i_nlink = 2;
	mark_buffer_dirty(dir_block);
	brelse (dir_block);
	inode->i_mode = S_IFDIR | mode;
	if (dir->i_mode & S_ISGID)
		inode->i_mode |= S_ISGID;
	mark_inode_dirty(inode);
	bh = ufs_add_entry (dir, dentry->d_name.name, dentry->d_name.len, &de, &err);
	if (!bh)
		goto out_no_entry;
	de->d_ino = SWAB32(inode->i_ino);
	ufs_set_de_type (de, inode->i_mode);
	dir->i_version = ++event;
	mark_buffer_dirty(bh);
	if (IS_SYNC(dir)) {
		ll_rw_block (WRITE, 1, &bh);
		wait_on_buffer (bh);
	}
	dir->i_nlink++;
	mark_inode_dirty(dir);
	d_instantiate(dentry, inode);
	brelse (bh);
	err = 0;
out:
	return err;

out_no_entry:
	inode->i_nlink = 0;
	mark_inode_dirty(inode);
	iput (inode);
	goto out;
}

/*
 * routine to check that the specified directory is empty (for rmdir)
 */
static int ufs_empty_dir (struct inode * inode)
{
	struct super_block * sb;
	unsigned long offset;
	struct buffer_head * bh;
	struct ufs_dir_entry * de, * de1;
	int err;
	unsigned swab;	
	
	sb = inode->i_sb;
	swab = sb->u.ufs_sb.s_swab;

	if (inode->i_size < UFS_DIR_REC_LEN(1) + UFS_DIR_REC_LEN(2) ||
	    !(bh = ufs_bread (inode, 0, 0, &err))) {
	    	ufs_warning (inode->i_sb, "empty_dir",
			      "bad directory (dir #%lu) - no data block",
			      inode->i_ino);
		return 1;
	}
	de = (struct ufs_dir_entry *) bh->b_data;
	de1 = (struct ufs_dir_entry *) ((char *) de + SWAB16(de->d_reclen));
	if (SWAB32(de->d_ino) != inode->i_ino || !SWAB32(de1->d_ino) || 
	    strcmp (".", de->d_name) || strcmp ("..", de1->d_name)) {
	    	ufs_warning (inode->i_sb, "empty_dir",
			      "bad directory (dir #%lu) - no `.' or `..'",
			      inode->i_ino);
		return 1;
	}
	offset = SWAB16(de->d_reclen) + SWAB16(de1->d_reclen);
	de = (struct ufs_dir_entry *) ((char *) de1 + SWAB16(de1->d_reclen));
	while (offset < inode->i_size ) {
		if (!bh || (void *) de >= (void *) (bh->b_data + sb->s_blocksize)) {
			brelse (bh);
			bh = ufs_bread (inode, offset >> sb->s_blocksize_bits, 1, &err);
	 		if (!bh) {
				ufs_error (sb, "empty_dir",
					    "directory #%lu contains a hole at offset %lu",
					    inode->i_ino, offset);
				offset += sb->s_blocksize;
				continue;
			}
			de = (struct ufs_dir_entry *) bh->b_data;
		}
		if (!ufs_check_dir_entry ("empty_dir", inode, de, bh, offset)) {
			brelse (bh);
			return 1;
		}
		if (SWAB32(de->d_ino)) {
			brelse (bh);
			return 0;
		}
		offset += SWAB16(de->d_reclen);
		de = (struct ufs_dir_entry *) ((char *) de + SWAB16(de->d_reclen));
	}
	brelse (bh);
	return 1;
}

static int ufs_rmdir (struct inode * dir, struct dentry *dentry)
{
	struct super_block *sb;
	int retval;
	struct inode * inode;
	struct buffer_head * bh;
	struct ufs_dir_entry * de;
	unsigned swab;
	
	sb = dir->i_sb;
	swab = sb->u.ufs_sb.s_swab;
		
	UFSD(("ENTER\n"))

	retval = -ENOENT;
	bh = ufs_find_entry (dir, dentry->d_name.name, dentry->d_name.len, &de);
	if (!bh)
		goto end_rmdir;

	inode = dentry->d_inode;
	DQUOT_INIT(inode);

	retval = -EIO;
	if (SWAB32(de->d_ino) != inode->i_ino)
		goto end_rmdir;

	retval = -ENOTEMPTY;
	if (!ufs_empty_dir (inode))
		goto end_rmdir;

	retval = ufs_delete_entry (dir, de, bh);
	dir->i_version = ++event;
	if (retval)
		goto end_rmdir;
	mark_buffer_dirty(bh);
	if (IS_SYNC(dir)) {
		ll_rw_block (WRITE, 1, &bh);
		wait_on_buffer (bh);
	}
	if (inode->i_nlink != 2)
		ufs_warning (inode->i_sb, "ufs_rmdir",
			      "empty directory has nlink!=2 (%d)",
			      inode->i_nlink);
	inode->i_version = ++event;
	inode->i_nlink = 0;
	inode->i_size = 0;
	mark_inode_dirty(inode);
	dir->i_nlink--;
	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	mark_inode_dirty(dir);

end_rmdir:
	brelse (bh);
	UFSD(("EXIT\n"))
	
	return retval;
}

static int ufs_unlink(struct inode * dir, struct dentry *dentry)
{
	struct super_block * sb;
	int retval;
	struct inode * inode;
	struct buffer_head * bh;
	struct ufs_dir_entry * de;
	unsigned flags, swab;

	sb = dir->i_sb;
	flags = sb->u.ufs_sb.s_flags;
	swab = sb->u.ufs_sb.s_swab;

	retval = -ENOENT;
	bh = ufs_find_entry (dir, dentry->d_name.name, dentry->d_name.len, &de);
	UFSD(("de: ino %u, reclen %u, namelen %u, name %s\n", SWAB32(de->d_ino),
		SWAB16(de->d_reclen), ufs_get_de_namlen(de), de->d_name))
	if (!bh)
		goto end_unlink;

	inode = dentry->d_inode;
	DQUOT_INIT(inode);

	retval = -EIO;
	if (SWAB32(de->d_ino) != inode->i_ino)
		goto end_unlink;
	
	if (!inode->i_nlink) {
		ufs_warning (inode->i_sb, "ufs_unlink",
			      "Deleting nonexistent file (%lu), %d",
			      inode->i_ino, inode->i_nlink);
		inode->i_nlink = 1;
	}
	retval = ufs_delete_entry (dir, de, bh);
	if (retval)
		goto end_unlink;
	dir->i_version = ++event;
	mark_buffer_dirty(bh);
	if (IS_SYNC(dir)) {
		ll_rw_block (WRITE, 1, &bh);
		wait_on_buffer (bh);
	}
	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	mark_inode_dirty(dir);
	inode->i_nlink--;
	mark_inode_dirty(inode);
	inode->i_ctime = dir->i_ctime;
	retval = 0;

end_unlink:
	brelse (bh);
	return retval;
}


/*
 * Create symbolic link. We use only slow symlinks at this time.
 */
static int ufs_symlink (struct inode * dir, struct dentry * dentry,
	const char * symname)
{
	struct super_block * sb = dir->i_sb;
	struct ufs_dir_entry * de;
	struct inode * inode;
	struct buffer_head * bh = NULL;
	unsigned l;
	int err;
	unsigned swab = sb->u.ufs_sb.s_swab;
	
	UFSD(("ENTER\n"))
	

	err = -ENAMETOOLONG;
	l = strlen(symname)+1;
	if (l > sb->s_blocksize)
		goto out;

	err = -EIO;
	
	if (!(inode = ufs_new_inode (dir, S_IFLNK, &err))) {
		return err;
	}
	inode->i_mode = S_IFLNK | S_IRWXUGO;

	if (l > sb->u.ufs_sb.s_uspi->s_maxsymlinklen) {
		/* slow symlink */
		inode->i_op = &page_symlink_inode_operations;
		inode->i_mapping->a_ops = &ufs_aops;
		err = block_symlink(inode, symname, l);
		if (err)
			goto out_no_entry;
	} else {
		/* fast symlink */
		inode->i_op = &ufs_fast_symlink_inode_operations;
		memcpy((char*)&inode->u.ufs_i.i_u1.i_data,symname,l);
		inode->i_size = l-1;
	}
	mark_inode_dirty(inode);

	bh = ufs_add_entry (dir, dentry->d_name.name, dentry->d_name.len, &de, &err);
	if (!bh)
		goto out_no_entry;
	de->d_ino = SWAB32(inode->i_ino);
	dir->i_version = ++event;
	mark_buffer_dirty(bh);
	if (IS_SYNC(dir)) {
		ll_rw_block (WRITE, 1, &bh);
		wait_on_buffer (bh);
	}
	brelse (bh);
	d_instantiate(dentry, inode);
	err = 0;
out:
	return err;

out_no_entry:
	inode->i_nlink--;
	mark_inode_dirty(inode);
	iput (inode);
	goto out;
}

static int ufs_link (struct dentry * old_dentry, struct inode * dir,
	struct dentry *dentry)
{
	struct inode *inode = old_dentry->d_inode;
	struct super_block * sb = inode->i_sb;
	struct ufs_dir_entry * de;
	struct buffer_head * bh;
	int err;
	unsigned swab = sb->u.ufs_sb.s_swab;
	
	if (S_ISDIR(inode->i_mode))
		return -EPERM;

	if (inode->i_nlink >= UFS_LINK_MAX)
		return -EMLINK;

	bh = ufs_add_entry (dir, dentry->d_name.name, dentry->d_name.len, &de, &err);
	if (!bh)
		return err;

	de->d_ino = SWAB32(inode->i_ino);
	dir->i_version = ++event;
	mark_buffer_dirty(bh);
	if (IS_SYNC(dir)) {
		ll_rw_block (WRITE, 1, &bh);
		wait_on_buffer (bh);
	}
	brelse (bh);
	inode->i_nlink++;
	inode->i_ctime = CURRENT_TIME;
	mark_inode_dirty(inode);
	atomic_inc(&inode->i_count);
	d_instantiate(dentry, inode);
	return 0;
}


#define PARENT_INO(buffer) \
	((struct ufs_dir_entry *) ((char *) buffer + \
	SWAB16(((struct ufs_dir_entry *) buffer)->d_reclen)))->d_ino
/*
 * Anybody can rename anything with this: the permission checks are left to the
 * higher-level routines.
 */
static int ufs_rename (struct inode * old_dir, struct dentry * old_dentry,
	struct inode * new_dir,	struct dentry * new_dentry )
{
	struct super_block * sb;
	struct inode * old_inode, * new_inode;
	struct buffer_head * old_bh, * new_bh, * dir_bh;
	struct ufs_dir_entry * old_de, * new_de;
	int retval;
	unsigned flags, swab;
	
	sb = old_dir->i_sb;
	flags = sb->u.ufs_sb.s_flags;
	swab = sb->u.ufs_sb.s_swab;

	UFSD(("ENTER\n"))
	
	old_inode = new_inode = NULL;
	old_bh = new_bh = dir_bh = NULL;
	new_de = NULL;

	old_bh = ufs_find_entry (old_dir, old_dentry->d_name.name, old_dentry->d_name.len, &old_de);
	/*
	 *  Check for inode number is _not_ due to possible IO errors.
	 *  We might rmdir the source, keep it as pwd of some process
	 *  and merrily kill the link to whatever was created under the
	 *  same name. Goodbye sticky bit ;-<
	 */
	retval = -ENOENT;
	old_inode = old_dentry->d_inode;
	if (!old_bh || SWAB32(old_de->d_ino) != old_inode->i_ino)
		goto end_rename;

	new_inode = new_dentry->d_inode;
	new_bh = ufs_find_entry (new_dir, new_dentry->d_name.name, new_dentry->d_name.len, &new_de);
	if (new_bh) {
		if (!new_inode) {
			brelse (new_bh);
			new_bh = NULL;
		} else {
			DQUOT_INIT(new_inode);
		}
	}
	if (S_ISDIR(old_inode->i_mode)) {
		if (new_inode) {
			retval = -ENOTEMPTY;
			if (!ufs_empty_dir (new_inode))
				goto end_rename;
		}

		retval = -EIO;
		dir_bh = ufs_bread (old_inode, 0, 0, &retval);
		if (!dir_bh)
			goto end_rename;
		if (SWAB32(PARENT_INO(dir_bh->b_data)) != old_dir->i_ino)
			goto end_rename;
		retval = -EMLINK;
		if (!new_inode && new_dir->i_nlink >= UFS_LINK_MAX)
			goto end_rename;
	}

	if (!new_bh)
		new_bh = ufs_add_entry (new_dir, new_dentry->d_name.name, new_dentry->d_name.len, &new_de,
					 &retval);
	if (!new_bh)
		goto end_rename;
	new_dir->i_version = ++event;

	/*
	 * ok, that's it
	 */
	new_de->d_ino = SWAB32(old_inode->i_ino);
	ufs_delete_entry (old_dir, old_de, old_bh);

	old_dir->i_version = ++event;
	if (new_inode) {
		new_inode->i_nlink--;
		new_inode->i_ctime = CURRENT_TIME;
		mark_inode_dirty(new_inode);
	}
	old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
	mark_inode_dirty(old_dir);
	if (dir_bh) {
		PARENT_INO(dir_bh->b_data) = SWAB32(new_dir->i_ino);
		mark_buffer_dirty(dir_bh);
		old_dir->i_nlink--;
		mark_inode_dirty(old_dir);
		if (new_inode) {
			new_inode->i_nlink--;
			mark_inode_dirty(new_inode);
		} else {
			new_dir->i_nlink++;
			mark_inode_dirty(new_dir);
		}
	}
	mark_buffer_dirty(old_bh);
	if (IS_SYNC(old_dir)) {
		ll_rw_block (WRITE, 1, &old_bh);
		wait_on_buffer (old_bh);
	}
	
	mark_buffer_dirty(new_bh);
	if (IS_SYNC(new_dir)) {
		ll_rw_block (WRITE, 1, &new_bh);
		wait_on_buffer (new_bh);
	}

	retval = 0;
end_rename:
	brelse (dir_bh);
	brelse (old_bh);
	brelse (new_bh);
	
	UFSD(("EXIT\n"))
	
	return retval;
}

struct inode_operations ufs_dir_inode_operations = {
	create:		ufs_create,
	lookup:		ufs_lookup,
	link:		ufs_link,
	unlink:		ufs_unlink,
	symlink:	ufs_symlink,
	mkdir:		ufs_mkdir,
	rmdir:		ufs_rmdir,
	mknod:		ufs_mknod,
	rename:		ufs_rename,
};