NFSv4: OPEN must handle the NFS4ERR_IO return code correctly

decode_op_hdr() cannot distinguish between an XDR decoding error and
the perfectly valid errorcode NFS4ERR_IO. This is normally not a
problem, but for the particular case of OPEN, we need to be able
to increment the NFSv4 open sequence id when the server returns
a valid response.

Reported-by: J Bruce Fields <bfields@fieldses.org>
Link: http://lkml.kernel.org/r/20131204210356.GA19452@fieldses.org
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Cc: stable@vger.kernel.org

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 5be2868..8c21d69 100644 (file)
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -3097,7 +3097,8 @@ out_overflow:
        return -EIO;
 }
 
-static int decode_op_hdr(struct xdr_stream *xdr, enum nfs_opnum4 expected)
+static bool __decode_op_hdr(struct xdr_stream *xdr, enum nfs_opnum4 expected,
+               int *nfs_retval)
 {
        __be32 *p;
        uint32_t opnum;
@@ -3107,19 +3108,32 @@ static int decode_op_hdr(struct xdr_stream *xdr, enum nfs_opnum4 expected)
        if (unlikely(!p))
                goto out_overflow;
        opnum = be32_to_cpup(p++);
-       if (opnum != expected) {
-               dprintk("nfs: Server returned operation"
-                       " %d but we issued a request for %d\n",
-                               opnum, expected);
-               return -EIO;
-       }
+       if (unlikely(opnum != expected))
+               goto out_bad_operation;
        nfserr = be32_to_cpup(p);
-       if (nfserr != NFS_OK)
-               return nfs4_stat_to_errno(nfserr);
-       return 0;
+       if (nfserr == NFS_OK)
+               *nfs_retval = 0;
+       else
+               *nfs_retval = nfs4_stat_to_errno(nfserr);
+       return true;
+out_bad_operation:
+       dprintk("nfs: Server returned operation"
+               " %d but we issued a request for %d\n",
+                       opnum, expected);
+       *nfs_retval = -EREMOTEIO;
+       return false;
 out_overflow:
        print_overflow_msg(__func__, xdr);
-       return -EIO;
+       *nfs_retval = -EIO;
+       return false;
+}
+
+static int decode_op_hdr(struct xdr_stream *xdr, enum nfs_opnum4 expected)
+{
+       int retval;
+
+       __decode_op_hdr(xdr, expected, &retval);
+       return retval;
 }
 
 /* Dummy routine */
@@ -5001,11 +5015,12 @@ static int decode_open(struct xdr_stream *xdr, struct nfs_openres *res)
        uint32_t savewords, bmlen, i;
        int status;
 
-       status = decode_op_hdr(xdr, OP_OPEN);
-       if (status != -EIO)
-               nfs_increment_open_seqid(status, res->seqid);
-       if (!status)
-               status = decode_stateid(xdr, &res->stateid);
+       if (!__decode_op_hdr(xdr, OP_OPEN, &status))
+               return status;
+       nfs_increment_open_seqid(status, res->seqid);
+       if (status)
+               return status;
+       status = decode_stateid(xdr, &res->stateid);
        if (unlikely(status))
                return status;