Re: [PATCH 6/8] nowait aio: ext4

On Mon 10-04-17 07:39:43, Christoph Hellwig wrote:

On Mon, Apr 10, 2017 at 02:37:50PM +0200, Jan Kara wrote:

quoted

I don't understand here. Do you want that all filesystems support NOWAIT
direct IO?

No.  Per-file_system_type is way to coarse grained.  All feature flag
needs to be per-file_operation at least for cases like ext4 with our
without extents (or journal) XFS v4 vs v5, different NFS versions, etc.

Ah, I see your point now. Thanks for patience. I think we could make this
work by making generic_file_write/read_iter() refuse NOWAIT IO with
EOPNOTSUPP and then only modify those few filesystems that implement their
own iter helpers and will not initially support NOWAIT IO. Sounds easy
enough.

								Honza
-- 
Jan Kara [off-list ref]
SUSE Labs, CR