On 2020/07/31 15:45, hch@xxxxxxxxxxxxx wrote: > On Fri, Jul 31, 2020 at 06:42:10AM +0000, Damien Le Moal wrote: >>> - 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, > 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. Which is fine with me. Just trying to say that I think this is exactly the discussion we need to start with. What interface do we implement... Allowing zone append only through zonefs as the raw block device equivalent, all the O_APPEND/RWF_APPEND semantic is defined and the "return written offset" implementation in VFS would be common for all file systems, including regular ones. Beside that, there is I think the question of short writes... Not sure if short writes can currently happen with async RWF_APPEND writes to regular files. I think not but that may depend on the FS. -- Damien Le Moal Western Digital Research
