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authorJ. Bruce Fields <bfields@redhat.com>2021-12-07 17:32:21 -0500
committerChuck Lever <chuck.lever@oracle.com>2022-01-08 14:42:01 -0500
commit3dcd1d8aab00c5d3a0a3725253c86440b1a0f5a7 (patch)
tree86652ac2c3ccb29826ef6024f8d9cd261d7fa729
parent70e94d757b3e1f46486d573729d84c8955c81dce (diff)
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>
-rw-r--r--fs/nfsd/nfs4state.c14
-rw-r--r--fs/nfsd/state.h4
2 files changed, 14 insertions, 4 deletions
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 1956d377d1a6..72e3833c3034 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -360,11 +360,13 @@ static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops = {
* st_{access,deny}_bmap field of the stateid, in order to track not
* only what share bits are currently in force, but also what
* combinations of share bits previous opens have used. This allows us
- * to enforce the recommendation of rfc 3530 14.2.19 that the server
- * return an error if the client attempt to downgrade to a combination
- * of share bits not explicable by closing some of its previous opens.
+ * to enforce the recommendation in
+ * https://datatracker.ietf.org/doc/html/rfc7530#section-16.19.4 that
+ * the server return an error if the client attempt to downgrade to a
+ * combination of share bits not explicable by closing some of its
+ * previous opens.
*
- * XXX: This enforcement is actually incomplete, since we don't keep
+ * This enforcement is arguably incomplete, since we don't keep
* track of access/deny bit combinations; so, e.g., we allow:
*
* OPEN allow read, deny write
@@ -372,6 +374,10 @@ static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops = {
* DOWNGRADE allow read, deny none
*
* which we should reject.
+ *
+ * But you could also argue that our current code is already overkill,
+ * since it only exists to return NFS4ERR_INVAL on incorrect client
+ * behavior.
*/
static unsigned int
bmap_to_share_mode(unsigned long bmap)
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;