On Fri, Jul 31, 2020 at 07:45:26AM +0100, hch@infradead.org wrote:

On Fri, Jul 31, 2020 at 06:42:10AM +0000, Damien Le Moal wrote:

quoted

quoted

- We may not be able to use RWF_APPEND, and need exposing a new
type/flag (RWF_INDIRECT_OFFSET etc.) user-space. Not sure if this
sounds outrageous, but is it OK to have uring-only flag which can be
combined with RWF_APPEND?

Why ? Where is the problem ? O_APPEND/RWF_APPEND is currently meaningless for
raw block device accesses. We could certainly define a meaning for these in the
context of zoned block devices.

We can't just add a meaning for O_APPEND on block devices now,

Make sense.

Is a new call system call for nameless writes called for instead then?
Then there is no baggage. Or is this completely stupid?

as it was previously silently ignored.  I also really don't think any
of these semantics even fit the block device to start with.  If you
want to work on raw zones use zonefs, that's what is exists for.

Using zonefs adds a slight VFS overhead. Fine if we want to live with
that, but I have a feeling if we want to do something like just testing
hot paths alone to compare apples to apples we'd want something more
fine grained.

  Luis