Add a github workflow test for root disk detection (#15267)

Use losetup to create fake disks, start a MinIO cluster, umount 
one disk, and fails if the mount point directory will have format.json
recreated. It should fail because the mount point directory will belong
to the root disk after unmount.

.github/workflows/go-healing.yml

@@ -48,3 +48,4 @@ jobs:
           sudo sysctl net.ipv6.conf.default.disable_ipv6=0
           make verify-healing
           make verify-healing-inconsistent-versions
+          make verify-healing-with-root-disks

Makefile

@@ -87,6 +87,11 @@ verify-healing: ## verify healing and replacing disks with minio binary
 	@(env bash $(PWD)/buildscripts/verify-healing.sh)
 	@(env bash $(PWD)/buildscripts/unaligned-healing.sh)
 
+verify-healing-with-root-disks:
+	@echo "Verify healing with root disks"
+	@GORACE=history_size=7 CGO_ENABLED=1 go build -race -tags kqueue -trimpath --ldflags "$(LDFLAGS)" -o $(PWD)/minio 1>/dev/null
+	@(env bash $(PWD)/buildscripts/verify-healing-with-root-disks.sh)
+
 verify-healing-inconsistent-versions: ## verify resolving inconsistent versions
 	@echo "Verify resolving inconsistent versions build with race"
 	@GORACE=history_size=7 CGO_ENABLED=1 go build -race -tags kqueue -trimpath --ldflags "$(LDFLAGS)" -o $(PWD)/minio 1>/dev/null

buildscripts/verify-healing-with-root-disks.sh

@@ -0,0 +1,97 @@
+#!/bin/bash -e
+
+set -E
+set -o pipefail
+set -x
+
+
+if [ ! -x "$PWD/minio" ]; then
+    echo "minio executable binary not found in current directory"
+    exit 1
+fi
+
+WORK_DIR="$(mktemp -d)"
+MINIO_CONFIG_DIR="$WORK_DIR/.minio"
+MINIO=( "$PWD/minio" --config-dir "$MINIO_CONFIG_DIR" server )
+
+
+function start_minio() {
+    start_port=$1
+
+    export MINIO_ROOT_USER=minio
+    export MINIO_ROOT_PASSWORD=minio123
+    unset MINIO_KMS_AUTO_ENCRYPTION # do not auto-encrypt objects
+    unset MINIO_CI_CD
+    unset CI
+
+    args=()
+    for i in $(seq 1 4); do
+            args+=("http://localhost:$[${start_port}+$i]${WORK_DIR}/mnt/disk$i/ ")
+    done
+
+    for i in $(seq 1 4); do
+            "${MINIO[@]}" --address ":$[$start_port+$i]" ${args[@]} 2>&1 >"${WORK_DIR}/server$i.log" &
+    done
+
+    # Wait until all nodes return 403
+    for i in $(seq 1 4); do
+	    while [ "$(curl -m 1 -s -o /dev/null -w "%{http_code}" http://localhost:$[$start_port+$i])" -ne "403" ]; do
+		    echo -n ".";
+                    sleep 1;
+            done
+    done
+
+ }
+
+# Prepare fake disks with losetup
+function prepare_block_devices() {
+        mkdir -p ${WORK_DIR}/disks/ ${WORK_DIR}/mnt/
+        for i in 1 2 3 4; do
+                dd if=/dev/zero of=${WORK_DIR}/disks/img.$i bs=1M count=2048
+                mkfs.ext4 -F ${WORK_DIR}/disks/img.$i
+                sudo mknod /dev/minio-loopdisk$i b 7 $[256-$i]
+                sudo losetup /dev/minio-loopdisk$i ${WORK_DIR}/disks/img.$i
+                mkdir -p ${WORK_DIR}/mnt/disk$i/
+                sudo mount /dev/minio-loopdisk$i ${WORK_DIR}/mnt/disk$i/
+                sudo chown "$(id -u):$(id -g)" /dev/minio-loopdisk$i ${WORK_DIR}/mnt/disk$i/
+        done
+}
+
+# Start a distributed MinIO setup, unmount one disk and check if it is formatted
+function main() {
+    start_port=$(shuf -i 10000-65000 -n 1)
+    start_minio ${start_port}
+
+    # Unmount the disk, after the unmount the device id
+    # /tmp/xxx/mnt/disk4 will be the same as '/' and it
+    # will be detected as root disk
+    while [ "$u" != "0" ]; do
+	    sudo umount ${WORK_DIR}/mnt/disk4/
+	    u=$?
+	    sleep 1
+    done
+
+    # Wait until MinIO self heal kicks in
+    sleep 60
+
+    if [ -f ${WORK_DIR}/mnt/disk4/.minio.sys/format.json ]; then
+	    echo "A root disk is formatted unexpectedely"
+            cat "${WORK_DIR}/server4.log"
+            exit -1
+    fi
+}
+
+function cleanup() {
+    pkill minio
+    sudo umount ${WORK_DIR}/mnt/disk{1..3}/
+    sudo rm /dev/minio-loopdisk*
+    rm -rf "$WORK_DIR"
+}
+
+( prepare_block_devices )
+( main "$@" )
+rv=$?
+
+cleanup
+exit "$rv"
+