On 2021/04/19 15:45, Christoph Hellwig wrote: > On Sat, Apr 17, 2021 at 11:33:23AM +0900, Damien Le Moal wrote: >> Synchronous writes to sequential zone files cannot use zone append >> operations if the underlying zoned device queue limit >> max_zone_append_sectors is 0, indicating that the device does not >> support this operation. In this case, fall back to using regular write >> operations. > > Zone append is a mandatory feature of the zoned device API. Yes, I am well aware of that. All physical zoned devices and null blk do support zone append, but the logical device created by dm-crypt is out. And we cannot simply disable zone support in dm-crypt as there are use cases out there in the field that I am aware of, in SMR space. So this series is a compromise: preserve dm-crypt zone support for SMR (no one uses the zone append emulation yet, as far as I know) by disabling zone append. For zonefs, we can: 1) refuse to mount if ZA is disabled, same as btrfs 2) Do as I did in the patch, fallback to regular writes since that is easy to do (zonefs file size tracks the WP position already). I chose option (2) to allow for SMR+dm-crypt to still work with zonefs. -- Damien Le Moal Western Digital Research
