On Tue, Sep 16, 2008 at 05:31:07PM -0400, Theodore Tso wrote: > On Mon, Sep 15, 2008 at 10:53:05AM -0700, Mark Fasheh wrote: > > On Mon, Sep 15, 2008 at 10:49:48AM -0400, Christoph Hellwig wrote: > > > I agree to you (or someone elses - don't remember anymore) suggestion > > > to put in more padding so we can add fields later. I strongly disagree > > > putting in features now that we neither have a user, nor a usecase or > > > testcase for. > > > > So, how about another 64 bits of padding in struct fiemap_extent? That could > > help cover future uses like compression, which might require another 64 bit > > offset field - we only have 32 bits of reserved space there right now. > > What I'd recommend is a 56 byte structure: Why not just make it 64 bytes? Sure, that's 8 extra bytes, but I find the power-of-2 size (and the extra space) comforting. (AFAIK, slab allocators will give you 64 bytes anyway; and I expect something similar on the user-space side of things.) ... > Yeah, it's a little extra memory per extent, but filesystems seem to > always invent new things, and it seem spretty clear that we have at > least two extensions on deck (compression, multiple storage devices) > both of which have at least one implementation that are either in the > kernel or will likely enter the kernel. So it's likely that there is > something that we may have missed, and leaving a little extra space > doesn't actually cost us that much. Right. Josef 'Jeff' Sipek. -- Once you have their hardware. Never give it back. (The First Rule of Hardware Acquisition) -- 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
