On Thu, Jun 12, 2025 at 07:20:45PM +0800, Zhang Yi wrote: > On 2025/6/12 12:47, Christoph Hellwig wrote: > > On Wed, Jun 11, 2025 at 03:31:21PM +0800, Zhang Yi wrote: > >>>> +/* supports unmap write zeroes command */ > >>>> +#define BLK_FEAT_WRITE_ZEROES_UNMAP ((__force blk_features_t)(1u << > >>>> 17)) > >>> > >>> > >>> Should this be exposed through sysfs as a read-only value? > >> > >> Uh, are you suggesting adding another sysfs interface to expose > >> this feature? > > > > That was the idea. Or do we have another way to report this capability? > > > > Exposing this feature looks useful, but I think adding a new interface > might be somewhat redundant, and it's also difficult to name the new > interface. What about extend this interface to include 3 types? When > read, it exposes the following: > > - none : the device doesn't support BLK_FEAT_WRITE_ZEROES_UNMAP. > - enabled : the device supports BLK_FEAT_WRITE_ZEROES_UNMAP, but the > BLK_FLAG_WRITE_ZEROES_UNMAP_DISABLED is not set. > - disabled : the device supports BLK_FEAT_WRITE_ZEROES_UNMAP, and the > BLK_FLAG_WRITE_ZEROES_UNMAP_DISABLED is set. > > Users can write '0' and '1' to disable and enable this operation if it > is not 'none', thoughts?
Perhaps it should reuse the enumeration pattern elsewhere in sysfs? For example, # cat /sys/block/sda/queue/scheduler none [mq-deadline] # echo none > /sys/block/sda/queue/scheduler # cat /sys/block/sda/queue/scheduler [none] mq-deadline (Annoying that this seems to be opencoded wherever it appears...) --D > Best regards, > Yi. > >
