NFSv4.1: Fix a protocol issue with CLOSE stateids

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.

Cc: stable@vger.kernel.org # v4.0+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 2923abf2fc0cda269b2a9d8cb4023e89d70e83b0..366b81c185f61ef1cf8b1734b910586a24d5ff3f 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1231,6 +1231,7 @@ static void nfs_resync_open_stateid_locked(struct nfs4_state *state)
 }
 
 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);
@@ -1249,8 +1250,9 @@ static void nfs_clear_open_stateid_locked(struct nfs4_state *state,
        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;
        }
@@ -1259,10 +1261,12 @@ static void nfs_clear_open_stateid_locked(struct nfs4_state *state,
        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);
@@ -2707,7 +2711,8 @@ static void nfs4_close_done(struct rpc_task *task, void *data)
                                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);