On 2020/03/11 1:42, Christoph Hellwig wrote: > On Tue, Mar 10, 2020 at 06:46:42PM +0900, Johannes Thumshirn wrote: >> For null_blk the emulation is way simpler, as null_blk's zoned block >> device emulation support already caches the write pointer position, so we >> only need to report the position back to the upper layers. Additional >> caching is not needed here. >> >> Testing has been conducted by translating RWF_APPEND DIOs into >> REQ_OP_ZONE_APPEND commands in the block device's direct I/O function and >> injecting errors by bypassing the block layer interface and directly >> writing to the disc via the SCSI generic interface. > > We really need a user of this to be useful upstream. Didn't you plan > to look into converting zonefs/iomap to use it? Without that it is > at best a RFC. Even better would be converting zonefs and the f2fs > zoned code so that can get rid of the old per-zone serialization in > the I/O scheduler entirely. I do not think we can get rid of it entirely as it is needed for applications using regular writes on raw zoned block devices. But the zone write locking will be completely bypassed for zone append writes issued by file systems. -- Damien Le Moal Western Digital Research
