linux-ext4 - Re: [Resubmit][PATCH 4/5] Secure Deletion and Trash-Bin Support for Ext4

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Date:	Thu, 01 Feb 2007 12:43:09 -0800
From:	Mingming Cao <cmm@...ibm.com>
To:	Harry Papaxenopoulos <harry@...sunysb.edu>
Cc:	linux-ext4@...r.kernel.org, ezk@...sunysb.edu, kolya@...sunysb.edu
Subject: Re: [Resubmit][PATCH 4/5] Secure Deletion and Trash-Bin Support
	for Ext4

On Wed, 2007-01-31 at 09:55 -0500, Harry Papaxenopoulos wrote:

> @@ -2077,6 +2079,10 @@ static int ext4_unlink(struct inode * di
>  	struct buffer_head * bh;
>  	struct ext4_dir_entry_2 * de;
>  	handle_t *handle;
> +	int trashed = 0;
> +#ifdef CONFIG_EXT4DEV_FS_TRASHBIN
> +	struct dentry *user_dentry = NULL;
> +#endif
> 
>  	/* Initialize quotas before so that eventual writes go
>  	 * in separate transaction */
> @@ -2105,13 +2111,41 @@ static int ext4_unlink(struct inode * di
>  			      inode->i_ino, inode->i_nlink);
>  		inode->i_nlink = 1;
>  	}
> -	retval = ext4_delete_entry(handle, dir, de, bh);
> +#ifdef CONFIG_EXT4DEV_FS_TRASHBIN
> +	if ((dentry->d_inode->i_sb->s_flags & MNT_TRASHBIN) &&
> +				(EXT4_I(dentry->d_inode)->i_flags &
> +				(EXT4_UNRM_FL | EXT4_SECRM_FL))) {
> +
> +		/*
> +		 * We put this code here to optimize the common case. Since
> +		 * lookups are expensive, we try to reserve from making any,
> +		 * unless one of the trash-bin flags are set. The cleanest
> +		 * way though is to probably move this code outside the
> +		 * above if statement.
> +		 */
> +		user_dentry = vfs_get_user_dentry(dir, 1);
> +		if (IS_ERR(user_dentry)) {
> +			retval = PTR_ERR(user_dentry);
> +			user_dentry = NULL;
> +			goto end_unlink;
> +		}
> +
> +		if (inode->i_nlink == 1 && user_dentry->d_inode &&
> +			   	user_dentry->d_inode->i_ino != dir->i_ino) {
> +			retval = vfs_trash_entry(dir, dentry);
> +			trashed = 1;
> +		}
> +	}
> +#endif
> +	if (!trashed)
> +		retval = ext4_delete_entry(handle, dir, de, bh);
>  	if (retval)
>  		goto end_unlink;
>  	dir->i_ctime = dir->i_mtime = CURRENT_TIME_SEC;
>  	ext4_update_dx_flag(dir);
>  	ext4_mark_inode_dirty(handle, dir);
> -	drop_nlink(inode);
> +	if (!trashed)
> +		drop_nlink(inode);
>  	if (!inode->i_nlink)
>  		ext4_orphan_add(handle, inode);
>  	inode->i_ctime = dir->i_ctime;
> @@ -2121,6 +2155,10 @@ static int ext4_unlink(struct inode * di
>  end_unlink:
>  	ext4_journal_stop(handle);
>  	brelse (bh);
> +#ifdef CONFIG_EXT4DEV_FS_TRASHBIN
> +	if (user_dentry)
> +		dput(user_dentry);
> +#endif
>  	return retval;
>  }

I feel we could move the trash bin feature check at the beginning of
ext4_unlink() call, we don't need to start a journal and find the entry
at all if we are going to move that file to trash bin, that's all
handles by rename.

Mingming



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