On 5/2/11 8:05 AM, Lukas Czerner wrote: > On Mon, 2 May 2011, Mike Snitzer wrote: ... >> The blkdev_issue_discard() change you propose could be fine (mask >> EOPNOTSUPP return if device advertises support for discards) -- though >> Eric said we shouldn't ever say we did something when we didn't. > > Exactly, so we should not say that it is not supported when it is, but > we just hit the "wrong" part of the device:) I would just very much like > to keep the abstraction of having one consistent device underneath the > file system and not deal with several devices, or regions with different > behaviour in the file system itself (let the pixies underneath deal with > that, after all not all of us are btrfs:)) I still think we need to stick with the simple rule: "EOPNOTSUPP returned for a particular bio means that it is not supported for that particular bio" - I don't know what else we can do, without creating an ambiguity... This does, however, suck for the layer calling in to a complex device. What is the overhead for sending discard bios down to a device that does not support it? -Eric -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
