Re: [PATCH 2/2] ext4: handle errors in ext4_clear_blocks()

[Ted Ts'o <tytso@mit.edu>]

On Tue, Mar 01, 2011 at 02:28:26PM +0200, Amir Goldstein wrote:
> +out_err:
> +	ext4_std_error(inode->i_sb, err);
> +	return err;

Umm, you do realize this function will mark the file system as dirty,
and possibly remount the file system read-only, or panic the system,
right?

That's appropriate for normal journal failures (since there's no
recovering from them), but if you're proposing that a simple lack of
free blocks when doing a COW operation will result in a ENOSPC, all a
malicious userspace application needs to do to potentially bring the
system down is to attempt to unlink or truncate a file while COW
snapshots are enabled.....

Do you really want me to include this patch?  I think you may want to
rethink how you want to handle this case....

						- Ted