HotFix: Disables rmtab functionality (v3.6.3)

Summary:
- This is a new feature for 3.6 to provide "show mount" functionality to
  clients.  It unfortunately is not scalable for large numbers of mounts
  due to the various activities done in the epoll loop causing IO stalls
  and very slow mount performance for NFS clients, especially nfs CLI
  clients.

Test Plan: - Built RCs, deployed to gfsinstabu.frc3c08

Reviewers: dph, sshreyas

Reviewed By: sshreyas

Subscribers: storage@

FB-commit-id: bf30931

Change-Id: I7d0e110be95d82e3d8be7d2ac7576386471c1a47
Signed-off-by: Kevin Vigor <kvigor@fb.com>
Reviewed-on: https://review.gluster.org/16859
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Shreyas Siravara <sshreyas@fb.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/xlators/nfs/server/src/mount3.c b/xlators/nfs/server/src/mount3.c
index 57d1874c79a..d6b07ed801c 100644
--- a/xlators/nfs/server/src/mount3.c
+++ b/xlators/nfs/server/src/mount3.c
@@ -36,6 +36,7 @@
 #include <sys/socket.h>
 #include <sys/uio.h>
 
+#define SUPPORT_RMTAB 0
 
 /* This macro will assist in freeing up entire link list
  * of host_auth_spec structure.
@@ -444,7 +445,7 @@ mount_open_rmtab (const char *rmtab, gf_store_handle_t **sh)
         return _gf_true;
 }
 
-
+#if SUPPORT_RMTAB
 /* Read the rmtab into a clean ms->mountlist.
  */
 static void
@@ -472,6 +473,7 @@ mount_read_rmtab (struct mount3_state *ms)
 out:
         gf_store_handle_destroy (sh);
 }
+#endif
 
 /* Write the ms->mountlist to the rmtab.
  *
@@ -597,7 +599,9 @@ mnt3svc_update_mountlist (struct mount3_state *ms, rpcsvc_request_t *req,
 
         nfs = (struct nfs_state *)ms->nfsx->private;
 
+#if SUPPORT_RMTAB
         update_rmtab = mount_open_rmtab (nfs->rmtab, &sh);
+#endif
 
         strncpy (me->exname, expname, MNTPATHLEN);
         /* Sometimes we don't care about the full path
@@ -791,7 +795,9 @@ mnt3svc_lookup_mount_cbk (call_frame_t *frame, void  *cookie,
         }
 
         snprintf (path, PATH_MAX, "/%s", mntxl->name);
+#if SUPPORT_RMTAB
         mnt3svc_update_mountlist (ms, req, path, NULL);
+#endif
         GF_FREE (path);
         if (gf_nfs_dvm_off (nfs_state (ms->nfsx))) {
                 fh = nfs3_fh_build_indexed_root_fh (ms->nfsx->children, mntxl);
@@ -2265,9 +2271,10 @@ __build_mountlist (struct mount3_state *ms, int *count)
         if ((!ms) || (!count))
                 return NULL;
 
+#if SUPPORT_RMTAB
         /* read rmtab, other peers might have updated it */
         mount_read_rmtab(ms);
-
+#endif
         *count = 0;
         gf_msg_debug (GF_MNT, 0, "Building mount list:");
         list_for_each_entry (me, &ms->mountlist, mlist) {
@@ -2399,7 +2406,9 @@ mnt3svc_umount (struct mount3_state *ms, char *dirpath, char *hostname)
 
         nfs = (struct nfs_state *)ms->nfsx->private;
 
+#if SUPPORT_RMTAB
         update_rmtab = mount_open_rmtab (nfs->rmtab, &sh);
+#endif
         if (update_rmtab) {
                 ret = gf_store_lock (sh);
                 if (ret)
@@ -3026,7 +3035,9 @@ mount3udp_add_mountlist (xlator_t *nfsx, char *host, char *export)
         LOCK (&ms->mountlock);
         {
                 list_add_tail (&me->mlist, &ms->mountlist);
+#if SUPPORT_RMTAB
                 mount_rewrite_rmtab(ms, NULL);
+#endif
         }
         UNLOCK (&ms->mountlock);
         return 0;