[PATCH] ceph: fix mdsmap decode for v >= 17

["Luís Henriques" <lhenriques@suse.de>]

Commit d93231a6bc8a ("ceph: prevent a client from exceeding the MDS
maximum xattr size") was merged before the corresponding MDS-side changes
have been merged.  With the introduction of 'bal_rank_mask' in the mdsmap,
the decoding of maps with v>=17 is now incorrect.  Fix this by skipping
the 'bal_rank_mask' string decoding.

Fixes: d93231a6bc8a ("ceph: prevent a client from exceeding the MDS maximum xattr size")
Signed-off-by: Luís Henriques <lhenriques@suse.de>
---
Hi!

This inconsistency was introduced by ceph PR #43284; I think that, before
picking this patch, we need to get PR #46357 merged to avoid new
problems.

Cheers,
--
Luís

 fs/ceph/mdsmap.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/ceph/mdsmap.c b/fs/ceph/mdsmap.c
index 3fbabc98e1f7..fe4f1a6c3465 100644
--- a/fs/ceph/mdsmap.c
+++ b/fs/ceph/mdsmap.c
@@ -379,6 +379,8 @@ struct ceph_mdsmap *ceph_mdsmap_decode(void **p, void *end, bool msgr2)
 		ceph_decode_skip_8(p, end, bad_ext);
 		/* required_client_features */
 		ceph_decode_skip_set(p, end, 64, bad_ext);
+		/* bal_rank_mask */
+		ceph_decode_skip_string(p, end, bad_ext);
 		ceph_decode_64_safe(p, end, m->m_max_xattr_size, bad_ext);
 	} else {
 		/* This forces the usage of the (sync) SETXATTR Op */