NFSD: Decrease nfsd_users in nfsd_startup_generic fail

A memory allocation failure could cause nfsd_startup_generic to fail, in
which case nfsd_users wouldn't be incorrectly left elevated.

After nfsd restarts nfsd_startup_generic will then succeed without doing
anything--the first consequence is likely nfs4_start_net finding a bad
laundry_wq and crashing.
Signed-off-by: NKinglong Mee <kinglongmee@gmail.com>
Fixes: 4539f149 "nfsd: replace boolean nfsd_up flag by users counter"
Cc: stable@vger.kernel.org
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfssvc.c

@@ -221,7 +221,8 @@ static int nfsd_startup_generic(int nrservs)
 	 */
 	ret = nfsd_racache_init(2*nrservs);
 	if (ret)
-		return ret;
+		goto dec_users;
+
 	ret = nfs4_state_start();
 	if (ret)
 		goto out_racache;
@@ -229,6 +230,8 @@ static int nfsd_startup_generic(int nrservs)
 
 out_racache:
 	nfsd_racache_shutdown();
+dec_users:
+	nfsd_users--;
 	return ret;
 }