On Mon, 2017-10-23 at 12:23 -0400, Jeff Layton wrote: > From: Jeff Layton <jlayton@xxxxxxxxxx> > > Since its inception, ceph has presented the fsid as an opaque value > without any sort of endianness conversion. This means that the value > presented is different on architectures of different endianness. > > While the value that should be stuffed into f_fsid is poorly-defined, > I think it would be best to strive for consistency here between > architectures, and clients (we need to present this properly to the > userland client as well). > > Change ceph_statfs to convert the opaque words to host-endian before > doing the xor. The value will change between reboots on big-endian > architectures, but it should not change on little-endian ones. > I should probably have sent this as an RFC, and that last sentence was poorly worded. Let me try again: "On an upgrade, a big-endian box may see a different fsid than it did before, but little-endian arches should see no change with this patch." > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> > --- > fs/ceph/super.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/fs/ceph/super.c b/fs/ceph/super.c > index e4082afedcb1..fe9fbb3f13f7 100644 > --- a/fs/ceph/super.c > +++ b/fs/ceph/super.c > @@ -84,8 +84,9 @@ static int ceph_statfs(struct dentry *dentry, struct kstatfs *buf) > buf->f_ffree = -1; > buf->f_namelen = NAME_MAX; > > - /* leave fsid little-endian, regardless of host endianness */ > - fsid = *(u64 *)(&monmap->fsid) ^ *((u64 *)&monmap->fsid + 1); > + /* Must convert the fsid, for consistent values across arches */ > + fsid = le64_to_cpu(*(__le64 *)(&monmap->fsid)) ^ > + le64_to_cpu(*((__le64 *)&monmap->fsid + 1)); > buf->f_fsid.val[0] = fsid & 0xffffffff; > buf->f_fsid.val[1] = fsid >> 32; > -- Jeff Layton <jlayton@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
