nfsd: print status when nfsd4_open fails to open file it just created

It's possible for nfsd to fail opening a file that it has just created.
When that happens, we throw a WARN but it doesn't include any info about
the error code. Print the status code to give us a bit more info.

Our QA group hit some of these warnings under some very heavy stress
testing. My suspicion is that they hit the file-max limit, but it's hard
to know for sure. Go ahead and add a -ENFILE mapping to
nfserr_serverfault to make the error more distinct (and correct).

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

2 files changed, 4 insertions, 1 deletions

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 29a617ebe38c..8611585f739d 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -460,7 +460,9 @@ nfsd4_open(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
          * set, (2) sets open->op_stateid, (3) sets open->op_delegation.
          */
         status = nfsd4_process_open2(rqstp, resfh, open);
-        WARN_ON(status && open->op_created);
+        WARN(status && open->op_created,
+             "nfsd4_process_open2 failed to open newly-created file! status=%u\n",
+             be32_to_cpu(status));
 out:
         if (resfh && resfh != &cstate->current_fh) {
                 fh_dup2(&cstate->current_fh, resfh);
diff --git a/fs/nfsd/nfsproc.c b/fs/nfsd/nfsproc.c
index b19c7e8bf64c..b8680738f588 100644
--- a/fs/nfsd/nfsproc.c
+++ b/fs/nfsd/nfsproc.c
@@ -745,6 +745,7 @@ nfserrno (int errno)
                 { nfserr_notsupp, -EOPNOTSUPP },
                 { nfserr_toosmall, -ETOOSMALL },
                 { nfserr_serverfault, -ESERVERFAULT },
+                { nfserr_serverfault, -ENFILE },
         };
         int     i;