On Mon 12-07-10 17:26:49, Lukas Czerner wrote: > On Mon, 12 Jul 2010, Jan Kara wrote: > > > > Those mount option has the same meaning as in ext4 file system. It > > > provide a way to enable/disable file system's trim support. The trim > > > support is off by default, thus nodiscard option is not actually > > > necessary. > > I kind of miss why ext3 should have a 'discard' mount option. When > > user calls DISCARD ioctl on the filesystem, then he probably wants > > discard to be performed. > > > > Honza > > You're right that it is not necessarily needed, but it is the same as in > ext4. For ext4 it's a bit different matter as it automatically sends discard requests from mballoc when a block is freed. It makes a good sense to have an option to enable / disable this. But even for ext4 it would make sense to me to be able to allow this ioctl but still disable the logic for automatic trimming... Thus my suggestion would be to make 'discard' mount option only influence automatic trimming in ext4 and consequently it does not make sense to have such an option for ext3... > If you want to be really sure that no unwanted trim will be send to the > device, 'nodiscard' mount option becomes handy. But I do not insist on it > and I can easily get rid of it. Yeah, but the ioctl can be unsafe only if there are HW bugs or the trim support is buggy. Of course, both can happen but I don't think it's serious enough to warrant a new mount option (as that costs us something as well - too much options => user confusion ;). Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
