On Thu, Sep 29, 2016 at 01:08:57PM -0700, Bart Van Assche wrote: > On 09/28/2016 07:19 PM, Darrick J. Wong wrote: > >After much discussion, it seems that the fallocate feature flag > >FALLOC_FL_ZERO_RANGE maps nicely to SCSI WRITE SAME; and the feature > >FALLOC_FL_PUNCH_HOLE maps nicely to the devices that have been > >whitelisted for zeroing SCSI UNMAP. Punch still requires that > >FALLOC_FL_KEEP_SIZE is set. A length that goes past the end of the > >device will be clamped to the device size if KEEP_SIZE is set; or will > >return -EINVAL if not. Both start and length must be aligned to the > >device's logical block size. > > > >Since the semantics of fallocate are fairly well established already, > >wire up the two pieces. The other fallocate variants (collapse range, > >insert range, and allocate blocks) are not supported. > > For the FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE > case, it's probably safer not to try to send a discard to block devices that > do not support discard in order not to hit block driver bugs. But that's > something we can still discuss later. Hence: I'll just change it to check the queue flags and post a new revision. At this point I might as well repost the whole thing to reflect the reviewed-bys. --D > Reviewed-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx> -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
