do not limit tmp space that agent remaps

https://www.pivotaltracker.com/story/show/117177967
[#117177967]

Signed-off-by: Aditya Mishra <amishra@pivotal.io>

platform/linux_platform.go

@@ -699,38 +699,34 @@ func (p linux) SetupTmpDir() error {
 		return nil
 	}
 
-	_, systemTmpDirIsMounted, err := p.IsMountPoint(systemTmpDir)
+	_, _, _, err = p.cmdRunner.RunCommand("mkdir", "-p", boshRootTmpPath)
 	if err != nil {
-		return bosherr.WrapErrorf(err, "Checking for mount point %s", systemTmpDir)
+		return bosherr.WrapError(err, "Creating root tmp dir")
 	}
 
-	if !systemTmpDirIsMounted {
-		// If it's not mounted on /tmp, blow it away
-		_, _, _, err = p.cmdRunner.RunCommand("truncate", "-s", "128M", boshRootTmpPath)
-		if err != nil {
-			return bosherr.WrapError(err, "Truncating root tmp dir")
-		}
+	bindMounter := boshdisk.NewLinuxBindMounter(p.diskManager.GetMounter())
+	mounted, err := bindMounter.IsMounted(boshRootTmpPath)
 
+	if !mounted && err == nil {
+		// change permissions
 		_, _, _, err = p.cmdRunner.RunCommand("chmod", "0700", boshRootTmpPath)
 		if err != nil {
 			return bosherr.WrapError(err, "Chmoding root tmp dir")
 		}
 
-		_, _, _, err = p.cmdRunner.RunCommand("mke2fs", "-t", "ext4", "-m", "1", "-F", boshRootTmpPath)
-		if err != nil {
-			return bosherr.WrapError(err, "Creating root tmp dir filesystem")
-		}
-
-		err = p.diskManager.GetMounter().Mount(boshRootTmpPath, systemTmpDir, "-t", "ext4", "-o", "loop,noexec")
+		// mount
+		err = bindMounter.Mount(boshRootTmpPath, systemTmpDir)
 		if err != nil {
-			return bosherr.WrapError(err, "Mounting root tmp dir over /tmp")
+			return bosherr.WrapError(err, "Bind mounting root tmp dir over /tmp")
 		}
 
-		// Change permissions for new mount point
+		// change permissions for mount point
 		err = p.changeTmpDirPermissions(systemTmpDir)
 		if err != nil {
 			return err
 		}
+	} else if err != nil {
+		return err
 	}
 
 	return nil

platform/linux_platform_test.go

@@ -2,13 +2,12 @@ package platform_test
 
 import (
 	"errors"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
 	"os"
 	"path"
 	"time"
 
-	. "github.com/onsi/ginkgo"
-	. "github.com/onsi/gomega"
-
 	fakedpresolv "github.com/cloudfoundry/bosh-agent/infrastructure/devicepathresolver/fakes"
 	. "github.com/cloudfoundry/bosh-agent/platform"
 	fakecert "github.com/cloudfoundry/bosh-agent/platform/cert/fakes"
@@ -1348,45 +1347,38 @@ Number  Start   End     Size    File system  Name             Flags
 					mounter.IsMountPointResult = false
 				})
 
-				It("creates new tmp filesystem of 128MB placed in data dir", func() {
+				It("creates a root_tmp folder", func() {
+					err := act()
+					Expect(err).NotTo(HaveOccurred())
+					Expect(cmdRunner.RunCommands[3]).To(Equal([]string{"mkdir", "-p", "/fake-dir/data/root_tmp"}))
+				})
+
+				It("changes permissions on the new bind mount folder", func() {
 					err := act()
 					Expect(err).NotTo(HaveOccurred())
 
-					Expect(cmdRunner.RunCommands[3]).To(Equal([]string{"truncate", "-s", "128M", "/fake-dir/data/root_tmp"}))
 					Expect(cmdRunner.RunCommands[4]).To(Equal([]string{"chmod", "0700", "/fake-dir/data/root_tmp"}))
-					Expect(cmdRunner.RunCommands[5]).To(Equal([]string{"mke2fs", "-t", "ext4", "-m", "1", "-F", "/fake-dir/data/root_tmp"}))
 				})
 
-				It("mounts the new tmp filesystem over /tmp", func() {
+				It("bind mounts it in /tmp", func() {
 					err := act()
 					Expect(err).NotTo(HaveOccurred())
 
 					Expect(len(mounter.MountPartitionPaths)).To(Equal(1))
 					Expect(mounter.MountPartitionPaths[0]).To(Equal("/fake-dir/data/root_tmp"))
-					Expect(mounter.MountMountPoints[0]).To(Equal("/tmp"))
-					Expect(mounter.MountMountOptions[0]).To(Equal([]string{"-t", "ext4", "-o", "loop,noexec"}))
 				})
 
-				It("returns error if mounting the new tmp filesystem fails", func() {
-					mounter.MountErr = errors.New("fake-mount-error")
-
-					err := act()
-					Expect(err).To(HaveOccurred())
-					Expect(err.Error()).To(ContainSubstring("fake-mount-error"))
-				})
-
-				It("changes permissions on /tmp again because it is a new mount", func() {
+				It("changes permissions for the system /tmp folder", func() {
 					err := act()
 					Expect(err).NotTo(HaveOccurred())
 
-					Expect(cmdRunner.RunCommands[6]).To(Equal([]string{"chown", "root:vcap", "/tmp"}))
-					Expect(cmdRunner.RunCommands[7]).To(Equal([]string{"chmod", "0770", "/tmp"}))
+					Expect(cmdRunner.RunCommands[5]).To(Equal([]string{"chown", "root:vcap", "/tmp"}))
 				})
 			})
 
 			Context("when /tmp is a mount point", func() {
 				BeforeEach(func() {
-					mounter.IsMountPointResult = true
+					mounter.IsMountedResult = true
 				})
 
 				It("returns without an error", func() {
@@ -1399,13 +1391,13 @@ Number  Start   End     Size    File system  Name             Flags
 
 			Context("when /tmp cannot be determined if it is a mount point", func() {
 				BeforeEach(func() {
-					mounter.IsMountPointErr = errors.New("fake-is-mount-point-error")
+					mounter.IsMountedErr = errors.New("fake-is-mounted-error")
 				})
 
 				It("returns error", func() {
 					err := act()
 					Expect(err).To(HaveOccurred())
-					Expect(err.Error()).To(ContainSubstring("fake-is-mount-point-error"))
+					Expect(err.Error()).To(ContainSubstring("fake-is-mounted-error"))
 				})
 
 				ItDoesNotTryToUseLoopDevice()