Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate super_operation

Christoph Hellwig
2010-11-19T15:50:10Z

On Fri, Nov 19, 2010 at 10:37:48AM -0500, Ted Ts'o wrote:
> I think the author of that slide deck was being a little hysterical.
> In nearly all of these cases, if the file system is comptently
> implemented (i.e., you don't do a trim on anything but a deleted file
> block, and _only_ when you know the deleted is committed, and only the
> filesystem --- not non-privileged users --- are allowed to use the
> TRIM command), there's no issue.

It's a huge issue for virtualization, where naive TRIM implementations
can expose data deleted in one VM to others. It's also a huge issues
for RAIDs as mentioned by you.