On 03/18/2014 10:43 AM, Christoph Hellwig wrote: > On Tue, Mar 18, 2014 at 09:00:07AM +1100, NeilBrown wrote: >> ESTALE is also returned if the filesystem does not support file-handle -> >> file mappings. >> On filesystems which don't provide export_operations (/sys /proc ubifs >> romfs cramfs nfs coda ... several others) name_to_handle_at will produce a >> generic handle using the 32 bit inode and 32 bit i_generation. > > Do we? Seems like the code is erroring out early if there are no > export_ops? It appears to me that Neil's statement isn't correct, at least for /proc and /sys (see my other mail, to Neil). I'm unsure about whether it is true for some of those other FSes thought. >> Does it? My understanding from "man libblkid" (it is a while since I've read >> the code) is that it either uses info in /dev/disks/by-* or reads directly >> from the block devices (maybe using /sys to find them?) and interprets the >> superblock to extract a UUID. > > It normally reads directly from disk, unless it has changed very > recently. Thanks. As noted in my mail, I solved this one by just saying a little less about libblkid. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
