Halo Replication feature for AFR translator

	Backport of https://review.gluster.org/16177
		    https://review.gluster.org/17174

Merged both these patches to make sure IPV6 changes don't make it to 3.11 at all.

Summary:
Halo Geo-replication is a feature which allows Gluster or NFS clients to write
locally to their region (as defined by a latency "halo" or threshold if you
like), and have their writes asynchronously propagate from their origin to the
rest of the cluster.  Clients can also write synchronously to the cluster
simply by specifying a halo-latency which is very large (e.g. 10seconds) which
will include all bricks.

In other words, it allows clients to decide at mount time if they desire
synchronous or asynchronous IO into a cluster and the cluster can support both
of these modes to any number of clients simultaneously.

There are a few new volume options due to this feature:
  halo-shd-latency:  The threshold below which self-heal daemons will
  consider children (bricks) connected.

  halo-nfsd-latency: The threshold below which NFS daemons will consider
  children (bricks) connected.

  halo-latency: The threshold below which all other clients will
  consider children (bricks) connected.

  halo-min-replicas: The minimum number of replicas which are to
  be enforced regardless of latency specified in the above 3 options.
  If the number of children falls below this threshold the next
  best (chosen by latency) shall be swapped in.

New FUSE mount options:
  halo-latency & halo-min-replicas: As descripted above.

This feature combined with multi-threaded SHD support (D1271745) results in
some pretty cool geo-replication possibilities.

Operational Notes:
- Global consistency is gaurenteed for synchronous clients, this is provided by
  the existing entry-locking mechanism.
- Asynchronous clients on the other hand and merely consistent to their region.
  Writes & deletes will be protected via entry-locks as usual preventing
  concurrent writes into files which are undergoing replication.  Read operations
  on the other hand should never block.
- Writes are allowed from _any_ region and propagated from the origin to all
  other regions.  The take away from this is care should be taken to ensure
  multiple writers do not write the same files resulting in a gfid split-brain
  which will require resolution via split-brain policies (majority, mtime &
  size).  Recommended method for preventing this is using the nfs-auth feature to
  define which region for each share has RW permissions, tiers not in the origin
  region should have RO perms.

TODO:
- Synchronous clients (including the SHD) should choose clients from their own
  region as preferred sources for reads.  Most of the plumbing is in place for
  this via the child_latency array.
- Better GFID split brain handling & better dent type split brain handling
  (i.e. create a trash can and move the offending files into it).
- Tagging in addition to latency as a means of defining which children you wish
  to synchronously write to

Test Plan:
- The usual suspects, clang, gcc w/ address sanitizer & valgrind
- Prove tests

Reviewers: jackl, dph, cjh, meyering

Reviewed By: meyering

Subscribers: ethanr

Differential Revision: https://phabricator.fb.com/D1272053

Tasks: 4117827

 >Change-Id: I694a9ab429722da538da171ec528406e77b5e6d1
 >BUG: 1428061
 >Signed-off-by: Kevin Vigor <kvigor@fb.com>
 >Reviewed-on: http://review.gluster.org/16099
 >Reviewed-on: https://review.gluster.org/16177
 >Tested-by: Pranith Kumar Karampuri <pkarampu@redhat.com>
 >Smoke: Gluster Build System <jenkins@build.gluster.org>
 >NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
 >CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
 >Reviewed-by: Pranith Kumar Karampuri <pkarampu@redhat.com>

BUG: 1448416
Change-Id: I694a9ab429722da538da171ec528406e77b5e6d1
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: https://review.gluster.org/17192
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Kaushal M <kaushal@redhat.com>

7 files changed, 53 insertions, 16 deletions

diff --git a/libglusterfs/src/common-utils.c b/libglusterfs/src/common-utils.c
index 56f545f28de..2acd83f36cf 100644
--- a/libglusterfs/src/common-utils.c
+++ b/libglusterfs/src/common-utils.c
@@ -194,26 +194,16 @@ gf_rev_dns_lookup (const char *ip)
 {
         char               *fqdn = NULL;
         int                ret  = 0;
-        struct sockaddr_in sa   = {0};
-        char               host_addr[256] = {0, };
 
         GF_VALIDATE_OR_GOTO ("resolver", ip, out);
 
-        sa.sin_family = AF_INET;
-        inet_pton (AF_INET, ip, &sa.sin_addr);
-        ret = getnameinfo ((struct sockaddr *)&sa, sizeof (sa), host_addr,
-                          sizeof (host_addr), NULL, 0, 0);
-
+        /* Get the FQDN */
+        ret =  gf_get_hostname_from_ip ((char *)ip, &fqdn);
         if (ret != 0) {
                 gf_msg ("resolver", GF_LOG_INFO, errno,
                         LG_MSG_RESOLVE_HOSTNAME_FAILED, "could not resolve "
                         "hostname for %s", ip);
-                goto out;
         }
-
-        /* Get the FQDN */
-        fqdn = gf_strdup (host_addr);
-
 out:
        return fqdn;
 }
@@ -3127,11 +3117,13 @@ gf_get_hostname_from_ip (char *client_ip, char **hostname)
         char                    *client_ip_copy               = NULL;
         char                    *tmp                          = NULL;
         char                    *ip                           = NULL;
+        size_t                   addr_sz                      = 0;
 
         /* if ipv4, reverse lookup the hostname to
          * allow FQDN based rpc authentication
          */
-        if (valid_ipv4_address (client_ip, strlen (client_ip), 0) == _gf_false) {
+        if (!valid_ipv6_address (client_ip, strlen (client_ip), 0) &&
+            !valid_ipv4_address (client_ip, strlen (client_ip), 0)) {
                 /* most times, we get a.b.c.d:port form, so check that */
                 client_ip_copy = gf_strdup (client_ip);
                 if (!client_ip_copy)
@@ -3144,12 +3136,14 @@ gf_get_hostname_from_ip (char *client_ip, char **hostname)
 
         if (valid_ipv4_address (ip, strlen (ip), 0) == _gf_true) {
                 client_sockaddr = (struct sockaddr *)&client_sock_in;
+                addr_sz = sizeof (client_sock_in);
                 client_sock_in.sin_family = AF_INET;
                 ret = inet_pton (AF_INET, ip,
                                  (void *)&client_sock_in.sin_addr.s_addr);
 
         } else if (valid_ipv6_address (ip, strlen (ip), 0) == _gf_true) {
                 client_sockaddr = (struct sockaddr *) &client_sock_in6;
+                addr_sz = sizeof (client_sock_in6);
 
                 client_sock_in6.sin6_family = AF_INET6;
                 ret = inet_pton (AF_INET6, ip,
@@ -3163,8 +3157,14 @@ gf_get_hostname_from_ip (char *client_ip, char **hostname)
                 goto out;
         }
 
+        /* You cannot just use sizeof (*client_sockaddr), as per the man page
+         * the (getnameinfo) size must be the size of the underlying sockaddr
+         * struct e.g. sockaddr_in6 or sockaddr_in.  Failure to do so will
+         * break IPv6 hostname resolution (IPv4 will work only because
+         * the sockaddr_in struct happens to be of the correct size).
+         */
         ret = getnameinfo (client_sockaddr,
-                           sizeof (*client_sockaddr),
+                           addr_sz,
                            client_hostname, sizeof (client_hostname),
                            NULL, 0, 0);
         if (ret) {
diff --git a/libglusterfs/src/defaults-tmpl.c b/libglusterfs/src/defaults-tmpl.c
index 5b7578b7c57..0889e07caa7 100644
--- a/libglusterfs/src/defaults-tmpl.c
+++ b/libglusterfs/src/defaults-tmpl.c
@@ -170,6 +170,18 @@ default_notify (xlator_t *this, int32_t event, void *data, ...)
                 }
         }
         break;
+        case GF_EVENT_CHILD_PING:
+        {
+                xlator_list_t *parent = this->parents;
+
+                while (parent) {
+                        if (parent->xlator->init_succeeded)
+                                xlator_notify (parent->xlator, event,
+                                               this, data);
+                        parent = parent->next;
+                }
+        }
+        break;
         default:
         {
                 xlator_list_t *parent = this->parents;
diff --git a/libglusterfs/src/latency.c b/libglusterfs/src/latency.c
index 5025de6c8cf..1d75f5b98ce 100644
--- a/libglusterfs/src/latency.c
+++ b/libglusterfs/src/latency.c
@@ -21,6 +21,7 @@
 #include "statedump.h"
 #include "libglusterfs-messages.h"
 
+static int gf_set_fop_from_fn_pointer_warning;
 void
 gf_set_fop_from_fn_pointer (call_frame_t *frame, struct xlator_fops *fops, void *fn)
 {
@@ -108,8 +109,15 @@ gf_set_fop_from_fn_pointer (call_frame_t *frame, struct xlator_fops *fops, void
                 fop = GF_FOP_READDIRP;
         else if (fops->getspec == *(fop_getspec_t *)&fn)
                 fop = GF_FOP_GETSPEC;
-        else
-                fop = -1;
+        else if (fops->ipc == *(fop_ipc_t *)&fn)
+                fop = GF_FOP_IPC;
+        else {
+                fop = GF_FOP_NULL;
+                GF_LOG_OCCASIONALLY(gf_set_fop_from_fn_pointer_warning,
+                                    "latency",
+                                    GF_LOG_WARNING,
+                                    "Unknown FOP type");
+        }
 
         frame->op   = fop;
 }
diff --git a/libglusterfs/src/mem-types.h b/libglusterfs/src/mem-types.h
index 6c0472f00b8..b41805e1f02 100644
--- a/libglusterfs/src/mem-types.h
+++ b/libglusterfs/src/mem-types.h
@@ -172,6 +172,7 @@ enum gf_common_mem_types_ {
         gf_common_mt_tbf_bucket_t,
         gf_common_mt_tbf_throttle_t,
         gf_common_mt_pthread_t,
+        gf_common_ping_local_t,
         gf_common_mt_end
 };
 #endif
diff --git a/libglusterfs/src/timespec.c b/libglusterfs/src/timespec.c
index f7b2bea2f30..903303d1380 100644
--- a/libglusterfs/src/timespec.c
+++ b/libglusterfs/src/timespec.c
@@ -60,3 +60,15 @@ void timespec_adjust_delta (struct timespec *ts, struct timespec delta)
         ts->tv_sec += ((ts->tv_nsec + delta.tv_nsec) / 1000000000);
         ts->tv_sec += delta.tv_sec;
 }
+
+void timespec_sub (const struct timespec *begin, const struct timespec *end,
+                   struct timespec *res)
+{
+        if (end->tv_nsec < begin->tv_nsec) {
+                res->tv_sec = end->tv_sec - begin->tv_sec - 1;
+                res->tv_nsec = end->tv_nsec + 1000000000 - begin->tv_nsec;
+        } else {
+                res->tv_sec = end->tv_sec - begin->tv_sec;
+                res->tv_nsec = end->tv_nsec - begin->tv_nsec;
+        }
+}
diff --git a/libglusterfs/src/timespec.h b/libglusterfs/src/timespec.h
index f37194b97cf..9c393ee7166 100644
--- a/libglusterfs/src/timespec.h
+++ b/libglusterfs/src/timespec.h
@@ -20,5 +20,8 @@
 
 void timespec_now (struct timespec *ts);
 void timespec_adjust_delta (struct timespec *ts, struct timespec delta);
+void timespec_sub (const struct timespec *begin,
+                   const struct timespec *end,
+                   struct timespec *res);
 
 #endif /*  __INCLUDE_TIMESPEC_H__ */
diff --git a/libglusterfs/src/xlator.h b/libglusterfs/src/xlator.h
index c2959efbd95..e0f82a70764 100644
--- a/libglusterfs/src/xlator.h
+++ b/libglusterfs/src/xlator.h
@@ -933,6 +933,7 @@ struct _xlator {
 
         gf_loglevel_t    loglevel;   /* Log level for translator */
 
+        int64_t             client_latency;
         /* for latency measurement */
         fop_latency_t latencies[GF_FOP_MAXVALUE];