"Martin K. Petersen" <martin.petersen@xxxxxxxxxx> writes: >>>>>> "Lukas" == Lukas Czerner <lczerner@xxxxxxxxxx> writes: > > Lukas> As Jeff Moyer pointed out we do not honor discard granularity > Lukas> while submitting REQ_DISCARD bios of size smaller than > Lukas> max_discard_sectors. That fact might have unwanted consequences > Lukas> of device ignoring the request, or even worse if device firmware > Lukas> is buggy. > > We've discussed this before and the consensus was not to do it. The > granularity is a hint, not a hard limit like max_discard_sectors. > > We want the reporting to be comprehensive throughout the block layer. If > we start aligning to the granularity at the top we lose information for > stacked devices below with a finer granularity. > > So if we were to align to the granularity we'd want to do it at the > bottom of the stack when we issue the command to the device. We've had a > few proposed patches to did that but so far we've only found one device > where it made a difference. And that case didn't justify adding a quirk. Hm, I wonder where it makes sense to document this. Maybe Documentation/block/queue-sysfs.txt, but I admit I wouldn't have looked there while reviewing this code. Cheers, Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
