NFS4: on a O_EXCL OPEN make sure SETATTR sets the fields holding the verifier

The Linux NFS4 client simply skips over the bitmask in an O_EXCL open
call and so it doesn't bother to reset any fields that may be holding
the verifier. This patch has us save the first two words of the bitmask
(which is all the current client has #defines for). The client then
later checks this bitmask and turns on the appropriate flags in the
sattr->ia_verify field for the following SETATTR call.

This patch only currently checks to see if the server used the atime
and mtime slots for the verifier (which is what the Linux server uses
for this). I'm not sure of what other fields the server could
reasonably use, but adding checks for others should be trivial.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 8003c91ccb9a..1fcca516e6ee 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -3269,7 +3269,7 @@ static int decode_delegation(struct xdr_stream *xdr, struct nfs_openres *res)
 static int decode_open(struct xdr_stream *xdr, struct nfs_openres *res)
 {
         __be32 *p;
-        uint32_t bmlen;
+	uint32_t savewords, bmlen, i;
         int status;
 
         status = decode_op_hdr(xdr, OP_OPEN);
@@ -3287,7 +3287,12 @@ static int decode_open(struct xdr_stream *xdr, struct nfs_openres *res)
                 goto xdr_error;
 
         READ_BUF(bmlen << 2);
-        p += bmlen;
+	savewords = min_t(uint32_t, bmlen, NFS4_BITMAP_SIZE);
+	for (i = 0; i < savewords; ++i)
+		READ32(res->attrset[i]);
+	for (; i < NFS4_BITMAP_SIZE; i++)
+		res->attrset[i] = 0;
+
 	return decode_delegation(xdr, res);
 xdr_error:
 	dprintk("%s: Bitmap too large! Length = %u\n", __FUNCTION__, bmlen);