provider/aws: Update aws_ebs_volume when attached (#14005)

Fixes: #12496

When an EBS volume was attached to an instance and the user tried to
resize, they would get an error as follows:

```
* aws_ebs_volume.ebs_data_volume: Error waiting for Volume (vol-027e83f7) to become available: unexpected state 'in-use', wanted target 'available'. last error: %!s(<nil>)
```

`available` is a state *only* when creating an EBS volume that is not attached. When an instance is attached, it will go into the state `in-use`. Therefore `in-use` is a valid state when modifying an EBS volume that is attached:

```
% make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAWSEBSVolume_'                                   ✹ ✭
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2017/04/27 07:08:18 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v -run=TestAccAWSEBSVolume_ -timeout 120m
=== RUN   TestAccAWSEBSVolume_importBasic
--- PASS: TestAccAWSEBSVolume_importBasic (41.10s)
=== RUN   TestAccAWSEBSVolume_basic
--- PASS: TestAccAWSEBSVolume_basic (38.22s)
=== RUN   TestAccAWSEBSVolume_updateAttachedEbsVolume
--- PASS: TestAccAWSEBSVolume_updateAttachedEbsVolume (199.11s)
=== RUN   TestAccAWSEBSVolume_updateSize
--- PASS: TestAccAWSEBSVolume_updateSize (70.53s)
=== RUN   TestAccAWSEBSVolume_updateType
--- PASS: TestAccAWSEBSVolume_updateType (69.75s)
=== RUN   TestAccAWSEBSVolume_updateIops
--- PASS: TestAccAWSEBSVolume_updateIops (70.38s)
=== RUN   TestAccAWSEBSVolume_kmsKey
--- PASS: TestAccAWSEBSVolume_kmsKey (76.64s)
=== RUN   TestAccAWSEBSVolume_NoIops
--- PASS: TestAccAWSEBSVolume_NoIops (39.80s)
=== RUN   TestAccAWSEBSVolume_withTags
--- PASS: TestAccAWSEBSVolume_withTags (38.04s)
PASS
ok  	github.com/hashicorp/terraform/builtin/providers/aws	643.609s
```

builtin/providers/aws/resource_aws_ebs_volume.go

@@ -179,7 +179,7 @@ func resourceAWSEbsVolumeUpdate(d *schema.ResourceData, meta interface{}) error
 
 		stateConf := &resource.StateChangeConf{
 			Pending:    []string{"creating", "modifying"},
-			Target:     []string{"available"},
+			Target:     []string{"available", "in-use"},
 			Refresh:    volumeStateRefreshFunc(conn, *result.VolumeModification.VolumeId),
 			Timeout:    5 * time.Minute,
 			Delay:      10 * time.Second,

builtin/providers/aws/resource_aws_ebs_volume_test.go

@@ -30,6 +30,31 @@ func TestAccAWSEBSVolume_basic(t *testing.T) {
 	})
 }
 
+func TestAccAWSEBSVolume_updateAttachedEbsVolume(t *testing.T) {
+	var v ec2.Volume
+	resource.Test(t, resource.TestCase{
+		PreCheck:      func() { testAccPreCheck(t) },
+		IDRefreshName: "aws_ebs_volume.test",
+		Providers:     testAccProviders,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccAwsEbsAttachedVolumeConfig,
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckVolumeExists("aws_ebs_volume.test", &v),
+					resource.TestCheckResourceAttr("aws_ebs_volume.test", "size", "10"),
+				),
+			},
+			{
+				Config: testAccAwsEbsAttachedVolumeConfigUpdateSize,
+				Check: resource.ComposeTestCheckFunc(
+					testAccCheckVolumeExists("aws_ebs_volume.test", &v),
+					resource.TestCheckResourceAttr("aws_ebs_volume.test", "size", "20"),
+				),
+			},
+		},
+	})
+}
+
 func TestAccAWSEBSVolume_updateSize(t *testing.T) {
 	var v ec2.Volume
 	resource.Test(t, resource.TestCase{
@@ -200,6 +225,124 @@ resource "aws_ebs_volume" "test" {
 }
 `
 
+const testAccAwsEbsAttachedVolumeConfig = `
+data "aws_ami" "debian_jessie_latest" {
+  most_recent = true
+
+  filter {
+    name   = "name"
+    values = ["debian-jessie-*"]
+  }
+
+  filter {
+    name   = "virtualization-type"
+    values = ["hvm"]
+  }
+
+  filter {
+    name   = "architecture"
+    values = ["x86_64"]
+  }
+
+  filter {
+    name   = "root-device-type"
+    values = ["ebs"]
+  }
+
+  owners = ["379101102735"] # Debian
+}
+
+resource "aws_instance" "test" {
+  ami = "${data.aws_ami.debian_jessie_latest.id}"
+  associate_public_ip_address = true
+  count = 1
+  instance_type = "t2.medium"
+
+  root_block_device {
+    volume_size           = "10"
+    volume_type           = "standard"
+    delete_on_termination = true
+  }
+
+  tags {
+    Name    = "test-terraform"
+  }
+}
+
+resource "aws_ebs_volume" "test" {
+  depends_on = ["aws_instance.test"]
+  availability_zone = "${aws_instance.test.availability_zone}"
+  type = "gp2"
+  size = "10"
+}
+
+resource "aws_volume_attachment" "test" {
+  depends_on  = ["aws_ebs_volume.test"]
+  device_name = "/dev/xvdg"
+  volume_id   = "${aws_ebs_volume.test.id}"
+  instance_id = "${aws_instance.test.id}"
+}
+`
+
+const testAccAwsEbsAttachedVolumeConfigUpdateSize = `
+data "aws_ami" "debian_jessie_latest" {
+  most_recent = true
+
+  filter {
+    name   = "name"
+    values = ["debian-jessie-*"]
+  }
+
+  filter {
+    name   = "virtualization-type"
+    values = ["hvm"]
+  }
+
+  filter {
+    name   = "architecture"
+    values = ["x86_64"]
+  }
+
+  filter {
+    name   = "root-device-type"
+    values = ["ebs"]
+  }
+
+  owners = ["379101102735"] # Debian
+}
+
+resource "aws_instance" "test" {
+  ami = "${data.aws_ami.debian_jessie_latest.id}"
+  associate_public_ip_address = true
+  count = 1
+  instance_type = "t2.medium"
+
+  root_block_device {
+    volume_size           = "10"
+    volume_type           = "standard"
+    delete_on_termination = true
+  }
+
+  tags {
+    Name    = "test-terraform"
+  }
+}
+
+resource "aws_ebs_volume" "test" {
+  depends_on = ["aws_instance.test"]
+  availability_zone = "${aws_instance.test.availability_zone}"
+  type = "gp2"
+  size = "20"
+}
+
+resource "aws_volume_attachment" "test" {
+  depends_on  = ["aws_ebs_volume.test"]
+  device_name = "/dev/xvdg"
+  volume_id   = "${aws_ebs_volume.test.id}"
+  instance_id = "${aws_instance.test.id}"
+}
+`
+
 const testAccAwsEbsVolumeConfigUpdateSize = `
 resource "aws_ebs_volume" "test" {
   availability_zone = "us-west-2a"