afr: add checks for allowing lookups

Problem:
In an arbiter volume, lookup was being served from one of the sink
bricks (source brick was down). shard uses the iatt values from lookup cbk
to calculate the size and block count, which in this case were incorrect
values. shard_local_t->last_block was thus initialised to -1, resulting
in an infinite while loop in shard_common_resolve_shards().

Fix:
Use client quorum logic to allow or fail the lookups from afr if there
are no readable subvolumes. So in replica-3 or arbiter vols, if there is
no good copy or if quorum is not met, fail lookup with ENOTCONN.

With this fix, we are also removing support for quorum-reads xlator
option. So if quorum is not met, neither read nor write txns are allowed
and we fail the fop with ENOTCONN.

Change-Id: Ic65c00c24f77ece007328b421494eee62a505fa0
BUG: 1467250
Signed-off-by: Ravishankar N <ravishankar@redhat.com>

1 files changed, 2 insertions, 5 deletions

diff --git a/xlators/cluster/afr/src/afr.c b/xlators/cluster/afr/src/afr.c
index 84dbcc04680..b18f60fcc7c 100644
--- a/xlators/cluster/afr/src/afr.c
+++ b/xlators/cluster/afr/src/afr.c
@@ -278,8 +278,6 @@ reconfigure (xlator_t *this, dict_t *options)
         GF_OPTION_RECONF ("heal-timeout", priv->shd.timeout, options,
                           int32, out);
 
-        GF_OPTION_RECONF ("quorum-reads", priv->quorum_reads, options,
-                          bool, out);
         GF_OPTION_RECONF ("consistent-metadata", priv->consistent_metadata,
                           options, bool, out);
 
@@ -554,7 +552,6 @@ init (xlator_t *this)
 	GF_OPTION_INIT ("iam-self-heal-daemon", priv->shd.iamshd, bool, out);
         GF_OPTION_INIT ("heal-timeout", priv->shd.timeout, int32, out);
 
-        GF_OPTION_INIT ("quorum-reads", priv->quorum_reads, bool, out);
         GF_OPTION_INIT ("consistent-metadata", priv->consistent_metadata, bool,
                         out);
         GF_OPTION_INIT ("consistent-io", priv->consistent_io, bool, out);
@@ -998,8 +995,8 @@ struct volume_options options[] = {
         { .key = {"quorum-reads"},
           .type = GF_OPTION_TYPE_BOOL,
           .default_value = "no",
-          .description = "If quorum-reads is \"true\" only allow reads if "
-                         "quorum is met when quorum is enabled.",
+          .description = "This option has been removed. Reads are not allowed "
+                          "if quorum is not met.",
         },
         { .key  = {"node-uuid"},
           .type = GF_OPTION_TYPE_STR,