On Wed, Aug 09, 2006 at 11:40:19PM -0700, Andrew Morton wrote: > On Wed, 09 Aug 2006 18:20:43 -0700 > Mingming Cao <cmm@xxxxxxxxxx> wrote: > > > > > Define SECTOR_FMT to print sector_t in proper format > > > > ... > > > > #define HAVE_SECTOR_T > > typedef u64 sector_t; > > +#define SECTOR_FMT "%llu" > > We've thus-far avoided doing this. In fact a similar construct in > device-mapper was recently removed. > > Unlike many other attempts, this one appears to be correct (people usually > get powerpc wrong, due to its u64=unsigned long). > > That being said, I'm not really sure we want to add this. It produces > rather nasty-looking source code and thus far we've just used %llu and we've > typecasted the sector_t to `unsigned long long'. That happens in a lot of > places in the kernel and perhaps we don't want to start innovating in ext4 > ;) > > That also being said... does a 32-bit sector_t make any sense on a > 48-bit-blocknumber filesystem? I'd have thought that we'd just make ext4 > depend on 64-bit sector_t and be done with it. Ext4 will support a 48-bit blocknumber format for extents, but I do want to make ext4 suitable as a general purpose filesystem, and 32-bit systems will be around for I fear far longer than people might wish. So while I agree that we shouldn't go _too_ far out of our way to make things efficient on 32-bit systems, if it's not that much work to support a 32-bit sector_t, we ought to do it. So how about a compromise? We allow for a 32-bit sector_t in ext4, but we drop the SECTOR_FMT, and rely on %llu and typecasts in printk's. Then the only other extra hair in the filesystem code will be a mount-time check to make sure we don't try to mount a large filesystem on system with a 32-bit sector_t. - Ted - 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
