On 06/17/2010 12:54 AM, Neil Brown wrote: > > If you export two subvolumes of a btrfs filesystem, they will both be > given the same uuid so lookups will be confused. > blkid cannot differentiate the two, so we must use the fsid from > statfs64 to identify the filesystem. > > We cannot tell if blkid or statfs is best without knowing internal > details of the filesystem in question, so we need to encode specific > knowledge of btrfs in mountd. This is unfortunate. > > To ensure smooth handling of this and possible future changes in uuid > generation, we add infrastructure for multiple different uuids to be > recognised on old filehandles, but only the preferred on is used on > new filehandles. > > Signed-off-by: NeilBrown <ne...@suse.de> > > -- > This is a substantially revised version of a patch I posted a while > ago. > I tried to find a way to do it would hard coding knowledge of btrfs in > nfs-utils, but it isn't possible. For some filesystems, f_fsid is > best, for some it is worst. No way to tell the difference. > > This patch add infrastructure so that if we find a better way to get a > good uuid (e.g. a new syscall), we can slot it in for new filehandles, > but old filehandles using the old uuid will still work. > > I believe this is ready for inclusion upstream.
Committed... steved. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
