afr: thin-arbiter read txn changes

If both data bricks are up, read subvol will be based on read_subvols.

If only one data brick is up:
- First qeury the data-brick that is up. If it blames the other brick,
allow the reads.

- If if doesn't, query the TA to obtain the source of truth.

TODO: See if in-memory state can be maintained for read txns (BZ 1624358).

updates: bz#1579788
Change-Id: I61eec35592af3a1aaf9f90846d9a358b2e4b2fcc
Signed-off-by: Ravishankar N <ravishankar@redhat.com>

2 files changed, 65 insertions, 0 deletions

diff --git a/tests/basic/afr/ta-read.t b/tests/basic/afr/ta-read.t
new file mode 100644
index 00000000000..f2b3c38e06c
--- /dev/null
+++ b/tests/basic/afr/ta-read.t
@@ -0,0 +1,60 @@
+#!/bin/bash
+
+# Test read transaction logic for thin-arbiter.
+
+. $(dirname $0)/../../include.rc
+. $(dirname $0)/../../volume.rc
+. $(dirname $0)/../../thin-arbiter.rc
+cleanup;
+TEST ta_create_brick_and_volfile brick0
+TEST ta_create_brick_and_volfile brick1
+TEST ta_create_ta_and_volfile ta
+TEST ta_start_brick_process brick0
+TEST ta_start_brick_process brick1
+TEST ta_start_ta_process ta
+
+TEST ta_create_mount_volfile brick0 brick1 ta
+TEST ta_start_mount_process $M0
+EXPECT_WITHIN $PROCESS_UP_TIMEOUT "1" ta_up_status $V0 $M0 0
+EXPECT_WITHIN $PROCESS_UP_TIMEOUT "trusted.afr.patchy-ta-2" ls $B0/ta
+
+TEST touch $M0/FILE
+TEST ls $B0/brick0/FILE
+TEST ls $B0/brick1/FILE
+TEST ! ls $B0/ta/FILE
+
+# Kill one brick and write to FILE.
+TEST ta_kill_brick brick0
+EXPECT_WITHIN $PROCESS_DOWN_TIMEOUT "0" afr_child_up_status_meta $M0 $V0-replicate-0 0
+echo "brick0 down">> $M0/FILE
+TEST [ $? -eq 0 ]
+EXPECT "000000010000000000000000" get_hex_xattr trusted.afr.$V0-client-0 $B0/brick1/FILE
+EXPECT "000000010000000000000000" get_hex_xattr trusted.afr.$V0-client-0 $B0/ta/trusted.afr.patchy-ta-2
+
+#Umount and mount to remove cached data.
+TEST umount $M0
+TEST ta_start_mount_process $M0
+EXPECT_WITHIN $PROCESS_UP_TIMEOUT "1" ta_up_status $V0 $M0 0
+EXPECT_WITHIN $PROCESS_UP_TIMEOUT "1" afr_child_up_status_meta $M0 $V0-replicate-0 1
+# Read must be allowed since good brick is up.
+TEST  cat $M0/FILE
+
+# Toggle good and bad data brick processes.
+TEST ta_start_brick_process brick0
+EXPECT_WITHIN $PROCESS_UP_TIMEOUT "1" afr_child_up_status_meta $M0 $V0-replicate-0 0
+TEST ta_kill_brick brick1
+EXPECT_WITHIN $PROCESS_DOWN_TIMEOUT "0" afr_child_up_status_meta $M0 $V0-replicate-0 1
+# Read must now fail.
+TEST ! cat $M0/FILE
+
+# Bring all data bricks up, and kill TA.
+TEST ta_start_brick_process brick1
+EXPECT_WITHIN $PROCESS_UP_TIMEOUT "1" afr_child_up_status_meta $M0 $V0-replicate-0 1
+TA_PID=$(ta_get_pid_by_brick_name ta)
+TEST [ -n $TA_PID ]
+TEST ta_kill_brick ta
+TA_PID=$(ta_get_pid_by_brick_name ta)
+TEST [ -z $TA_PID ]
+# Read must now succeed.
+TEST cat $M0/FILE
+cleanup;
diff --git a/tests/thin-arbiter.rc b/tests/thin-arbiter.rc
index 8bb888a7471..36d11cea61d 100644
--- a/tests/thin-arbiter.rc
+++ b/tests/thin-arbiter.rc
@@ -419,6 +419,11 @@ function ta_kill_brick()
         kill -9 $p
 }
 
+function ta_get_pid_by_brick_name()
+{
+        cat $B0/${1}.pid
+}
+
 function ta_up_status()
 {
         local v=$1