Re: [RFC][PATCH] direct-io: btrfs: avoid splitting dio requests for non-btrfs filesystems

[Christoph Hellwig <hch@infradead.org>]

On Tue, Nov 02, 2010 at 10:57:18AM -0400, Josef Bacik wrote:
> (which I did anyway because of my bug).  So maybe the right idea is to rip out
> my logical offset tests altogether and fix dio so we treat buffer_boundary()
> like gospel.  That way Btrfs can get what it needs without having this weird
> special code, and then we can look at how other fs's set buffer_boundary (I'm
> pretty sure ext2/3 are the only ones) and make sure they are setting it when
> they really mean to.

That sounds pretty reasonable to me.  I really don't like the flag in
the kiocb in this patch, and handling it as part of the get_blocks
callback sounds much better to me.  I don't know enough about the
bounary blocks to know if we can reuse them - if we can it's perfect,
if not another buffer flag seems like the way to go.