Patch "NFSv4.1: Fix a protocol issue with CLOSE stateids" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

NFSv4.1: Fix a protocol issue with CLOSE stateids

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
nfsv4.1-fix-a-protocol-issue-with-close-stateids.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Trond Myklebust <[email protected]>
Date: Sun, 30 Aug 2015 18:37:59 -0700
Subject: NFSv4.1: Fix a protocol issue with CLOSE stateids

From: Trond Myklebust <[email protected]>

commit 4a1e2feb9d246775dee0f78ed5b18826bae2b1c5 upstream.

According to RFC5661 Section 18.2.4, CLOSE is supposed to return the zero stateid. This means that nfs_clear_open_stateid_locked() cannot assume that the result stateid will always match the 'other' field of the existing open stateid when trying to determine a race with a parallel OPEN.

Instead, we look at the argument, and check for matches.

---
 fs/nfs/nfs4proc.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

@@ -1216,6 +1216,7 @@ static void nfs_resync_open_stateid_lock
 }
 
 static void nfs_clear_open_stateid_locked(struct nfs4_state *state,
+		nfs4_stateid *arg_stateid,
 		nfs4_stateid *stateid, fmode_t fmode)
 {
 	clear_bit(NFS_O_RDWR_STATE, &state->flags);

@@ -1234,8 +1235,9 @@ static void nfs_clear_open_stateid_locke
 	if (stateid == NULL)
 		return;
 	/* Handle races with OPEN */
-	if (!nfs4_stateid_match_other(stateid, &state->open_stateid) ||
-	    !nfs4_stateid_is_newer(stateid, &state->open_stateid)) {
+	if (!nfs4_stateid_match_other(arg_stateid, &state->open_stateid) ||
+	    (nfs4_stateid_match_other(stateid, &state->open_stateid) &&
+	    !nfs4_stateid_is_newer(stateid, &state->open_stateid))) {
 		nfs_resync_open_stateid_locked(state);
 		return;
 	}

@@ -1244,10 +1246,12 @@ static void nfs_clear_open_stateid_locke
 	nfs4_stateid_copy(&state->open_stateid, stateid);
 }
 
-static void nfs_clear_open_stateid(struct nfs4_state *state, nfs4_stateid *stateid, fmode_t fmode)
+static void nfs_clear_open_stateid(struct nfs4_state *state,
+	nfs4_stateid *arg_stateid,
+	nfs4_stateid *stateid, fmode_t fmode)
 {
 	write_seqlock(&state->seqlock);
-	nfs_clear_open_stateid_locked(state, stateid, fmode);
+	nfs_clear_open_stateid_locked(state, arg_stateid, stateid, fmode);
 	write_sequnlock(&state->seqlock);
 	if (test_bit(NFS_STATE_RECLAIM_NOGRACE, &state->flags))
 		nfs4_schedule_state_manager(state->owner->so_server->nfs_client);

@@ -2672,7 +2676,8 @@ static void nfs4_close_done(struct rpc_t
 				goto out_release;
 			}
 	}
-	nfs_clear_open_stateid(state, res_stateid, calldata->arg.fmode);
+	nfs_clear_open_stateid(state, &calldata->arg.stateid,
+			res_stateid, calldata->arg.fmode);
 out_release:
 	nfs_release_seqid(calldata->arg.seqid);
 	nfs_refresh_inode(calldata->inode, calldata->res.fattr);

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/nfs41-flexfiles-zero-out-ds-write-wcc.patch queue-4.1/nfs-nfs_set_pgio_error-sometimes-misses-errors.patch queue-4.1/nfs-fix-a-null-pointer-dereference-of-migration-recovery-ops-for-v4.2-client.patch queue-4.1/sunrpc-xs_reset_transport-must-mark-the-connection-as-disconnected.patch queue-4.1/nfs-don-t-let-the-ctime-override-attribute-barriers.patch queue-4.1/sunrpc-fix-a-thinko-in-xs_connect.patch queue-4.1/nfsv4-don-t-set-setattr-for-o_rdonly-o_excl.patch queue-4.1/nfs41-flexfiles-update-inode-after-write-finishes.patch queue-4.1/nfsv4.1-pnfs-fix-borken-function-_same_data_server_addrs_locked.patch queue-4.1/nfsv4-force-a-post-op-attribute-update-when-holding-a-delegation.patch queue-4.1/nfsv4-pnfs-ensure-we-don-t-miss-a-file-extension.patch queue-4.1/nfsv4.1-flexfiles-fix-a-protocol-error-in-layoutreturn.patch queue-4.1/revert-nfsv4-remove-incorrect-check-in-can_open_delegated.patch queue-4.1/nfsv4.1-fix-a-protocol-issue-with-close-stateids.patch