Revert "nfsd4: remove check_conflicting_opens warning"

commit 4aa5e002034f0701c3335379fd6c22d7f3338cce upstream.

This reverts commit 50747dd5e47b "nfsd4: remove check_conflicting_opens
warning", as a prerequisite for reverting 94415b06eb8a, which has a
serious bug.

Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 1d2cd6a88f61d22ace07b9325ac0cae1e4171a23..932873cc1fa1b2490586aa720765be2be82dede0 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -4957,6 +4957,7 @@ static int nfsd4_check_conflicting_opens(struct nfs4_client *clp,
                writes--;
        if (fp->fi_fds[O_RDWR])
                writes--;
+       WARN_ON_ONCE(writes < 0);
        if (writes > 0)
                return -EAGAIN;
        spin_lock(&fp->fi_lock);