Re: [patch] RFC directio: partial writes support

[Dmitry Monakhov <dmonakhov@openvz.org>]

Dmitry Monakhov <dmonakhov@openvz.org> writes:

> Can someone please describe me why directio deny partial writes.
> For example if someone try to write 100Mb but file system has less
> data it return ENOSPC in the middle of block allocation.
> All allocated blocks will be truncated (it may be 100Mb -4k) end
> ENOSPC will be returned. As far as i remember direct_io always act
> like this, but i never asked why?
> Why do we have to give up all the progress we made?
> In fact partial writes are possible in case of holes, when we 
> fall back to buffered write. XFS implemented partial writes.
>
> I've done trivial changes and it works like charm. 
> Let's enable partial writes support and allow caller to define
> this behavior.
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