On Oct 05, 2006 21:31 -0700, Andrew Morton wrote: > If you mount the filesystem with `-t ext4dev -o extents' then create some > extenty files, then unount it and then mount it without `-o extents', the > driver will then refuse to create extenty files. > > IOW: you need to give it `-o extents' each time. > > That seems fairly pointless. In fact, if I'd created the fs with `mke2fs > -O extents' (which doesn't work at present) then I'd expect it to use > extents from thereon after, without requiring `mount -o extents'. I think this is an oversight. For Lustre we wanted the ability to mount ext3 filesystems with or without extents, because different customers have different levels of tolerance for risk. These days all of our customers use extents (better performance in conjunction with mballoc), but the patches have not been changed for ext4 (which should really default to using extents on a filesystem with the INCOMPAT_EXTENT feature set unless told otherwise). That is a necessity for filesystems larger than 2^32 blocks, since there is no way to create old block-mapped files past that limit. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc. - 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
