On 08/18/2011 05:49 PM, Lukas Czerner wrote: > On Thu, 18 Aug 2011, Jeff Moyer wrote: >> Seems you missed the bizarre case of configuring a loop device over top >> of a block device. > > Wow, that is a bizarre case I did not think about at all. But since it > is so bizarre, do we even care ? The thing is that the only case where > it would make a difference is if the loop device is put on top of block > device which actually supports discard. > > In order to fix that I would need to dig out the actual limits for that > device and set that appropriately for the loop device. Is that worth it > ? It is not like someone will ever do that (or should) :). It is bizarre (and being device-mapper developer I surely know better way :-) but people are still using that. Historically one of the use of underlying block device was cryptoloop, but here I think it should be completely deprecated (cryptsetup can handle all old loop modes as well and default modes for cryptoloop are not safe). [Can we finally remove crypto loop option it from kernel? ... ok, just tried:)] There is also out of tree loop-aes based on heavily patched loop device which usually uses block device underneath (cryptsetup already can handle all loop-aes modes as well). Sometimes it is used with --offset parameter for some reason (like linear device-mapper mapping). So I do not care if you do not support discard here but please do not break support for block device mapped through loop. Thanks, Milan -- 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
