Re: using O_DIRECT

[Andrea Arcangeli <andrea@suse.de>]

On Mon, Sep 03, 2001 at 03:13:42PM -0500, Bob McElrath wrote:
> I have written a small program to use O_DIRECT (attached), after
> applying your patch o_direct-14 to kernel 2.4.9.  Opening the file with
> O_DIRECT is successful, but attempts to write to the fd return EINVAL.
> 
> Am I doing something wrong?  Should I have to recompile glibc too?

eh, the alignment and size of the buffer have basically the same
restrictions of running read/write on a raw device, with the only
difference that for rawio the granularity is the hardblocksize, while
for O_DIRECT the granularity is the softblocksize of the filesystem.

We'll have to relax the granularity of the I/O down to the hardblocksize
for O_DIRECT too eventually.

Andrea