>Right now NFSD depends on FS_REQUIRES_DEV to be set in sb->s_type->fs_flags >or manually set fsid= in /etc/exports in order to export filesystem. >But there are non-device based filesystems (Lustre for example ;) ) that >would like to be exported via NFS without guiding users through this >fsid= business. >... >I wonder if e.g. another export op could be introduced to ask filesystem >for its unique id It would also be quite valuable with device-based filesystems, for the opposite reason. That a device-based filesystem can be uniquely identified by the device number of its device is a fiction that is getting harder to entertain every year. Device numbers of devices change and a device can contain multiple filesystems over time. When Linux added the export ID, at a time when other operating systems were addressing the problem with the kind of fsid you're proposing, I believe the point was that in Linux you can have multiple incompatible exports of the same filesystem -- to give a client the right data, you'd need to know from which export, not just which filesystem, a given filehandle came. Nonetheless, I agree that it would be good to have the option of using a filesystem identifier instead of an export identifier. In a system that only does simple uniform exports of whole filesystems, I think filesystem ID works perfectly, and it is much easier to use. -- Bryan Henderson IBM Almaden Research Center San Jose CA Filesystems - 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
