nfsd4: fix bad seqid on lock request incompatible with open mode

The failure to return a stateowner from nfs4_preprocess_seqid_op() means
in the case where a lock request is of a type incompatible with an open
(due to, e.g., an application attempting a write lock on a file open for
read), means that fs/nfsd/nfs4xdr.c:ENCODE_SEQID_OP_TAIL() never bumps
the seqid as it should.  The client, attempting to close the file
afterwards, then gets an (incorrect) bad sequence id error.  Worse, this
prevents the open file from ever being closed, so we leak state.

Thanks to Benny Halevy and Trond Myklebust for analysis, and to Steven
Wilton for the report and extensive data-gathering.

Cc: Benny Halevy <bhalevy@panasas.com>
Cc: Steven Wilton <steven.wilton@team.eftel.com.au>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 11aa4b6b4fa26918da5f9aa945daee8a0300ca47..c4b10a1e6c30c4e94ac8e080ae4357848b4aa771 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2093,8 +2093,10 @@ nfs4_preprocess_seqid_op(struct svc_fh *current_fh, u32 seqid, stateid_t *statei
                goto check_replay;
        }
 
+       *stpp = stp;
+       *sopp = sop = stp->st_stateowner;
+
        if (lock) {
-               struct nfs4_stateowner *sop = stp->st_stateowner;
                clientid_t *lockclid = &lock->v.new.clientid;
                struct nfs4_client *clp = sop->so_client;
                int lkflg = 0;
@@ -2124,9 +2126,6 @@ nfs4_preprocess_seqid_op(struct svc_fh *current_fh, u32 seqid, stateid_t *statei
                return nfserr_bad_stateid;
        }
 
-       *stpp = stp;
-       *sopp = sop = stp->st_stateowner;
-
        /*
        *  We now validate the seqid and stateid generation numbers.
        *  For the moment, we ignore the possibility of