From ba1949db0ac905e6e615af6d6abb7e3f7588d250 Mon Sep 17 00:00:00 2001
From: Ricardo Rosales <missingcharacter@gmail.com>
Date: Thu, 3 Sep 2020 09:35:36 -0500
Subject: [PATCH 1/4] Keeping master version of ebs-nvme-mapping.sh

---
 999-aws-ebs-nvme.rules | 1 +
 nextephemeraldevice.sh | 8 ++++++++
 2 files changed, 9 insertions(+)
 create mode 100644 nextephemeraldevice.sh

diff --git a/999-aws-ebs-nvme.rules b/999-aws-ebs-nvme.rules
index a514019..c6baed5 100644
--- a/999-aws-ebs-nvme.rules
+++ b/999-aws-ebs-nvme.rules
@@ -1 +1,2 @@
 SUBSYSTEM=="block", KERNEL=="nvme[0-9]*n1", ATTRS{model}=="Amazon Elastic Block Store", PROGRAM+="/usr/local/sbin/ebs-nvme-mapping.sh /dev/%k" SYMLINK+="%c"
+KERNEL=="nvme[0-9]*n[0-9]*", ENV{DEVTYPE}=="disk", ATTRS{model}=="Amazon EC2 NVMe Instance Storage", PROGRAM="/usr/local/bin/nextdevice %k", SYMLINK+="%c"
diff --git a/nextephemeraldevice.sh b/nextephemeraldevice.sh
new file mode 100644
index 0000000..9842bd3
--- /dev/null
+++ b/nextephemeraldevice.sh
@@ -0,0 +1,8 @@
+#!/usr/bin/env bash
+
+kern_name=${1}
+incr=0
+while [[ -e "/dev/ephemeral${incr}" ]] && [[ $(readlink "/dev/ephemeral${incr}") != "${kern_name}" ]]; do
+  incr=$[$i+1]
+done
+echo "ephemeral${incr}"

From af010259d5650508f8aa200cd0316aae8d8ad730 Mon Sep 17 00:00:00 2001
From: Ricardo Rosales <missingcharacter@gmail.com>
Date: Tue, 21 Apr 2020 23:05:36 -0500
Subject: [PATCH 2/4] Adding reference to udev rule to nextephemeraldevice
 script

---
 nextephemeraldevice.sh | 1 +
 1 file changed, 1 insertion(+)

diff --git a/nextephemeraldevice.sh b/nextephemeraldevice.sh
index 9842bd3..a32d305 100644
--- a/nextephemeraldevice.sh
+++ b/nextephemeraldevice.sh
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+# To be used with the udev rule: /etc/udev/rules.d/999-aws-ebs-nvme.rules
 
 kern_name=${1}
 incr=0

From 6aca438b7a126e9872fd54d58cf39ccf64c60954 Mon Sep 17 00:00:00 2001
From: Ricardo Rosales <missingcharacter@gmail.com>
Date: Thu, 3 Sep 2020 09:39:19 -0500
Subject: [PATCH 3/4] Keeping master version of ebs-nvme-mapping.sh

---
 999-aws-ebs-nvme.rules | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/999-aws-ebs-nvme.rules b/999-aws-ebs-nvme.rules
index c6baed5..20617ba 100644
--- a/999-aws-ebs-nvme.rules
+++ b/999-aws-ebs-nvme.rules
@@ -1,2 +1,2 @@
 SUBSYSTEM=="block", KERNEL=="nvme[0-9]*n1", ATTRS{model}=="Amazon Elastic Block Store", PROGRAM+="/usr/local/sbin/ebs-nvme-mapping.sh /dev/%k" SYMLINK+="%c"
-KERNEL=="nvme[0-9]*n[0-9]*", ENV{DEVTYPE}=="disk", ATTRS{model}=="Amazon EC2 NVMe Instance Storage", PROGRAM="/usr/local/bin/nextdevice %k", SYMLINK+="%c"
+KERNEL=="nvme[0-9]*n[0-9]*", ENV{DEVTYPE}=="disk", ATTRS{model}=="Amazon EC2 NVMe Instance Storage", PROGRAM="/usr/local/bin/nextephemeraldevice.sh %k", SYMLINK+="%c"

From 1a8da64ff5005ae76724ca5cda1c1a098b543f43 Mon Sep 17 00:00:00 2001
From: Ricardo Rosales <missingcharacter@gmail.com>
Date: Thu, 3 Sep 2020 17:24:30 -0500
Subject: [PATCH 4/4] adding lock file to ephemeral script

---
 nextephemeraldevice.sh | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/nextephemeraldevice.sh b/nextephemeraldevice.sh
index a32d305..14a4237 100644
--- a/nextephemeraldevice.sh
+++ b/nextephemeraldevice.sh
@@ -1,9 +1,27 @@
 #!/usr/bin/env bash
 # To be used with the udev rule: /etc/udev/rules.d/999-aws-ebs-nvme.rules
 
+# check if lock file exists
+script_name="$(basename $0)"
+pid_file="/tmp/${script_name}.lock"
+counter=0
+until [ $counter -eq 5 ] || [[ ! -e "${pid_file}" ]] ; do
+  sleep $(( counter++ ))
+done
+
+# create lock file if it does not exist
+if [[ -e "${pid_file}" ]]; then
+  echo "Lock file ${pid_file} still exists after counter ended" >&2
+  exit 1
+else
+  touch "${pid_file}"
+fi
+
 kern_name=${1}
 incr=0
 while [[ -e "/dev/ephemeral${incr}" ]] && [[ $(readlink "/dev/ephemeral${incr}") != "${kern_name}" ]]; do
   incr=$[$i+1]
 done
+# remove lock file
+rm "${pid_file}"
 echo "ephemeral${incr}"