Trash spec: caching the size of the trash directory

[Alexander Larsson]

On Fri, 2009-08-14 at 13:24 +0800, PCMan wrote:
> If this is going to be supported, I'd suggest that we also move all of
> the information in *.trashinfo files to this metadata file to reduce
> excessive I/O, disk space waste, and performance penalty needed to
> maintain the whole trash bin. In this way every time we changed
> something in the trash bin, only one metadata file needs to be
> updated.

The trashinfo file creation is used to get atomicity when picking a
in-trash filename. This cannot be done with a single file and will risk
data loss in some race conditions.