Re: [fuse-devel] Does fuse support direct_io?

[Miklos S. <mi...@sz...>]

On Sat, 17 Jan 2009, Anand Avati wrote:
> >
> >  - backup program reads file without O_DIRECT
> >  - database writes file with O_DIRECT
> 
> How different is this situation from disk filesytems like ext3? How
> hard would it be to invalidate the block cache of that inode during
> this stage of O_DIRECT write?

Have a look at fs/direct-io.c in the linux tree.  OK, some of that
deals with asynchronous I/O, but there are some hairy locking issues
in there, and still bugs are popping up where the interation of direct
I/O and buffered I/O is causing problems.

Believe me, it's far from trivial.

Miklos