cluster/dht: Correct min_free_disk behaviour

Problem:
Files were being created in subvol which had less than
min_free_disk available even in the cases where other
subvols with more space were available.

Solution:
Changed the logic to look for subvol which has more
space available.
In cases where all the subvols have lesser than
Min_free_disk available , the one with max space and
atleast one inode is available.

Known Issue: Cannot ensure that first file that is
created right after min-free-value is crossed on a
brick will get created in other brick because disk
usage stat takes some time to update in glusterprocess.
Will fix that as part of another bug.

Change-Id: If3ae0bf5a44f8739ce35b3ee3f191009ddd44455
BUG: 858488
Signed-off-by: Raghavendra Talur <rtalur@redhat.com>
Reviewed-on: http://review.gluster.org/4420
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 114 insertions, 0 deletions

diff --git a/tests/bugs/bug-858488-min-free-disk.t b/tests/bugs/bug-858488-min-free-disk.t
new file mode 100644
index 00000000000..43ef1496ba1
--- /dev/null
+++ b/tests/bugs/bug-858488-min-free-disk.t
@@ -0,0 +1,114 @@
+#!/bin/bash
+
+. $(dirname $0)/../include.rc
+. $(dirname $0)/../volume.rc
+
+cleanup;
+
+function pidgrep()
+{
+    ps ax | grep "$1" | awk '{print $1}' | head -1
+}
+
+## Start glusterd
+TEST glusterd;
+TEST pidof glusterd;
+TEST $CLI volume info;
+
+## Lets create partitions for bricks
+TEST truncate -s 100M $B0/brick1
+TEST truncate -s 200M $B0/brick2
+TEST LO1=`losetup --find --show $B0/brick1`
+TEST mkfs.xfs $LO1
+TEST LO2=`losetup --find --show $B0/brick2`
+TEST mkfs.xfs $LO2
+TEST mkdir -p $B0/${V0}1 $B0/${V0}2
+TEST mount -t xfs $LO1 $B0/${V0}1
+TEST mount -t xfs $LO2 $B0/${V0}2
+
+
+## Lets create volume
+TEST $CLI volume create $V0 $H0:$B0/${V0}{1,2};
+
+## Verify volume is created
+EXPECT "$V0" volinfo_field $V0 'Volume Name';
+EXPECT 'Created' volinfo_field $V0 'Status';
+
+## Start volume and verify
+TEST $CLI volume start $V0;
+EXPECT 'Started' volinfo_field $V0 'Status';
+TEST glusterfs -s $H0 --volfile-id=$V0 --acl $M0
+MOUNT_PID=`ps ax |grep "glusterfs -s $H0 --volfile-id=$V0 --acl $M0" | awk '{print $1}' | head -1`
+## Real test starts here
+## ----------------------------------------------------------------------------
+
+MINFREEDISKVALUE=90
+
+## Set min free disk to MINFREEDISKVALUE percent
+TEST $CLI volume set $V0 cluster.min-free-disk $MINFREEDISKVALUE
+
+## We need to have file name to brick map based on hash.
+## We will use this info in test case 0.
+i=1
+CONTINUE=2
+BRICK1FILE=0
+BRICK2FILE=0
+while [[ $CONTINUE -ne 0 ]]
+do
+        dd if=/dev/zero of=$M0/file$i.data bs=1024 count=1024 1>/dev/null 2>&1
+
+        if  [[ -e  $B0/${V0}1/file$i.data &&  $BRICK1FILE = "0" ]]
+        then
+                BRICK1FILE=file$i.data
+                CONTINUE=$CONTINUE-1
+        fi
+
+        if [[ -e  $B0/${V0}2/file$i.data &&  $BRICK2FILE = "0" ]]
+        then
+                BRICK2FILE=file$i.data
+                CONTINUE=$CONTINUE-1
+        fi
+
+        rm $M0/file$i.data
+        let i++
+done
+
+
+## Bring free space on one of the bricks to less than minfree value by
+## creating one big file.
+dd if=/dev/zero of=$M0/fillonebrick.data bs=1024 count=25600 1>/dev/null 2>&1
+
+#Lets find out where it was created
+if [ -f $B0/${V0}1/fillonebrick.data ]
+then
+        FILETOCREATE=$BRICK1FILE
+        OTHERBRICK=$B0/${V0}2
+else
+        FILETOCREATE=$BRICK2FILE
+        OTHERBRICK=$B0/${V0}1
+fi
+
+##--------------------------------TEST CASE 0-----------------------------------
+## If we try to create a file which should go into full brick as per hash, it
+## should go into the other brick instead.
+
+## Before that let us create files just to make gluster refresh the stat
+## Using touch so it should not change the disk usage stats
+for k in {1..20};
+do
+        touch $M0/dummyfile$k
+done
+
+dd if=/dev/zero of=$M0/$FILETOCREATE bs=1024 count=2048 1>/dev/null 2>&1
+TEST [ -e $OTHERBRICK/$FILETOCREATE ]
+
+## Done testing, lets clean up
+EXPECT "$MOUNT_PID" pidgrep $MOUNT_PID
+TEST rm -rf $M0/*
+
+## Finish up
+TEST $CLI volume stop $V0;
+EXPECT 'Stopped' volinfo_field $V0 'Status';
+$CLI volume delete $V0;
+
+cleanup;