nfsd: improve stateid access bitmask documentation

The use of the bitmaps is confusing.  Add a cross-reference to make it
easier to find the existing comment.  Add an updated reference with URL
to make it quicker to look up.  And a bit more editorializing about the
value of this.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index e73bdbb1634a..6eb3c7157214 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -568,6 +568,10 @@ struct nfs4_ol_stateid {
 	struct list_head		st_locks;
 	struct nfs4_stateowner		*st_stateowner;
 	struct nfs4_clnt_odstate	*st_clnt_odstate;
+/*
+ * These bitmasks use 3 separate bits for READ, ALLOW, and BOTH; see the
+ * comment above bmap_to_share_mode() for explanation:
+ */
 	unsigned char			st_access_bmap;
 	unsigned char			st_deny_bmap;
 	struct nfs4_ol_stateid		*st_openstp;