Re: [RFC PATCH] f2fs: preserve direct write semantics when buffering is forced

[Damien Le Moal]

On Thu, 2023-03-23 at 15:14 -0700, Jaegeuk Kim wrote:
> On 03/20, Christoph Hellwig wrote:
> > On Mon, Feb 20, 2023 at 01:20:04PM +0100, Hans Holmberg wrote:
> > > A) Supporting proper direct writes for zoned block devices would
> > > be the best, but it is currently not supported (probably for
> > > a good but non-obvious reason). Would it be feasible to
> > > implement proper direct IO?
> > 
> > I don't think why not.  In many ways direct writes to zoned devices
> > should be easier than non-direct writes.
> > 
> > Any comments from the maintainers why the direct I/O writes to
> > zoned
> > devices are disabled?  I could not find anything helpful in the
> > comments
> > or commit logs.
> 
> The direct IO wants to overwrite the data on the same block address,
> while
> zoned device does not support it?

Surely that is not the case with LFS mode, doesn't it ? Otherwise, even
buffered overwrites would have an issue.