nfsd: Don't keep looking up unhashed files in the nfsd file cache

commit d30881f upstream.

If a file is unhashed, then we're going to reject it anyway and retry,
so make sure we skip it when we're doing the RCU lockless lookup.
This avoids a number of unnecessary nfserr_jukebox returns from
nfsd_file_acquire()

Fixes: 65294c1 ("nfsd: add a new struct file caching facility to nfsd")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/nfsd/filecache.c

@@ -897,6 +897,8 @@ nfsd_file_find_locked(struct inode *inode, unsigned int may_flags,
  continue;
  if (!nfsd_match_cred(nf->nf_cred, current_cred()))
  continue;
+ if (!test_bit(NFSD_FILE_HASHED, &nf->nf_flags))
+ continue;
  if (nfsd_file_get(nf) != NULL)
  return nf;
  }