Make swap size configurable (home-assistant#3882)

Allow configuration of the swap size via /etc/default/haos-swapfile file. By
setting the SWAPSIZE variable in this file, swapfile get recreated on the next
reboot to the defined size. Size can be either in bytes or with optional units
(B/K/M/G, accepting some variations but always interpreted as power of 10). The
size is then rounded to 4k block size. If no override is defined or the value
can't be parsed, it falls back to previously used 33% of system RAM.

Fixes home-assistant#968

buildroot-external/rootfs-overlay/usr/lib/systemd/system/etc-default.mount

@@ -0,0 +1,13 @@
+[Unit]
+Description=Persistent /etc/default directory
+Requires=mnt-overlay.mount
+After=mnt-overlay.mount
+
+[Mount]
+What=/mnt/overlay/etc/default
+Where=/etc/default
+Type=None
+Options=bind
+
+[Install]
+WantedBy=hassos-bind.target

buildroot-external/rootfs-overlay/usr/lib/systemd/system/haos-swapfile.service

@@ -1,8 +1,8 @@
 [Unit]
 Description=HAOS swap
 DefaultDependencies=no
-Requires=mnt-data.mount
-After=mnt-data.mount [email protected]
+Requires=etc-default.mount mnt-data.mount
+After=etc-default.mount mnt-data.mount [email protected]
 Before=mnt-data-swapfile.swap
 
 [Service]

buildroot-external/rootfs-overlay/usr/lib/systemd/system/mnt-data-swapfile.swap

@@ -1,5 +1,6 @@
 [Unit]
 Description=HAOS swap file
+ConditionFileNotEmpty=/mnt/data/swapfile
 
 [Swap]
 What=/mnt/data/swapfile

buildroot-external/rootfs-overlay/usr/libexec/haos-swapfile

@@ -1,24 +1,59 @@
 #!/bin/sh
 set -e
 
-swapfile="/mnt/data/swapfile"
+size2kilobytes() {
+	bytes="$(echo "$1" | awk \
+	  'BEGIN{IGNORECASE = 1}
+	   function tobytes(n,b,p) {printf "%u\n", n*b^p/1024}
+	   /[0-9]B?$/{tobytes($1,  1, 0); next};
+	   /K(i?B)?$/{tobytes($1,  2, 10); next};
+	   /M(i?B)?$/{tobytes($1,  2, 20); next};
+	   /G(i?B)?$/{tobytes($1,  2, 30); next};
+	   {print -1}')"
+	echo "$bytes"
+}
+
+if [ -f /etc/default/haos-swapfile ]; then
+    # shellcheck disable=SC1091
+    . /etc/default/haos-swapfile
+fi
+SWAPFILE="/mnt/data/swapfile"
+
+# Swap size in kilobytes (as it's also what meminfo shows)
+SWAPSIZE="$(size2kilobytes "${SWAPSIZE}")"
+
+if [ -z "${SWAPSIZE}" ] || [ "${SWAPSIZE}" = "-1" ]; then
+	# Default to 33% of total memory
+	SWAPSIZE="$(awk '/MemTotal/{ print int($2 * 0.33) }' /proc/meminfo)"
+	echo "[INFO] Using default swapsize of 33% RAM (${SWAPSIZE} kB)"
+fi
+
 # Swap space in 4k blocks
-swapsize="$(awk '/MemTotal/{ print int($2 * 0.33 / 4) }' /proc/meminfo)"
+SWAPSIZE_BLOCKS=$((SWAPSIZE / 4))
 
+if [ "${SWAPSIZE_BLOCKS}" -lt 10 ]; then
+    echo "[INFO] Requested swap size smaller than 40kB, disabling swap"
 
-if [ ! -s "${swapfile}" ] || [ "$(stat "${swapfile}" -c '%s')" -lt $((swapsize * 4096)) ]; then
-	# Check free space (in 4k blocks)
-	if [ "$(stat -f /mnt/data -c '%f')" -lt "${swapsize}" ]; then
-		echo "[WARNING] Not enough space to allocate swapfile"
-		exit 1
-	fi
+    if [ -f "${SWAPFILE}" ]; then
+        echo "[INFO] Removing existing swapfile"
+        rm -f "${SWAPFILE}"
+    fi
 
-	echo "[INFO] Creating swapfile of size $((swapsize *4))k"
-	umask 0077
-	dd if=/dev/zero of="${swapfile}" bs=4k count="${swapsize}"
+    exit 0
 fi
 
-if ! swaplabel "${swapfile}" > /dev/null 2>&1; then
-	/usr/lib/systemd/systemd-makefs swap "${swapfile}"
+if [ ! -s "${SWAPFILE}" ] || [ "$(stat "${SWAPFILE}" -c '%s')" -ne $((SWAPSIZE_BLOCKS * 4096)) ]; then
+    # Check free space (in 4k blocks)
+    if [ "$(stat -f /mnt/data -c '%f')" -lt "${SWAPSIZE_BLOCKS}" ]; then
+        echo "[ERROR] Not enough space to allocate swapfile"
+        exit 1
+    fi
+
+    echo "[INFO] Creating swapfile of size ${SWAPSIZE} kB (rounded to ${SWAPSIZE_BLOCKS} blocks)"
+    umask 0077
+    dd if=/dev/zero of="${SWAPFILE}" bs=4k count="${SWAPSIZE_BLOCKS}"
 fi
 
+if ! swaplabel "${SWAPFILE}" > /dev/null 2>&1; then
+    /usr/lib/systemd/systemd-makefs swap "${SWAPFILE}"
+fi

tests/smoke_test/test_basic.py

@@ -78,6 +78,31 @@ def test_systemctl_check_no_failed(shell):
     assert "0 loaded units listed." in output, f"Some units failed:\n{"\n".join(output)}"
 
 
+@pytest.mark.dependency(depends=["test_init"])
+def test_custom_swap_size(shell, target):
+    output = shell.run_check("stat -c '%s' /mnt/data/swapfile")
+    # set new swap size to half of the previous size - round to 4k blocks
+    new_swap_size = (int(output[0]) // 2 // 4096) * 4096
+    shell.run_check(f"echo 'SWAPSIZE={new_swap_size/1024/1024}M' > /etc/default/haos-swapfile; reboot")
+    # reactivate ShellDriver to handle login again
+    target.deactivate(shell)
+    target.activate(shell)
+    output = shell.run_check("stat -c '%s' /mnt/data/swapfile")
+    assert int(output[0]) == new_swap_size, f"Incorrect swap size {new_swap_size}B: {output}"
+
+
+@pytest.mark.dependency(depends=["test_custom_swap_size"])
+def test_no_swap(shell, target):
+    output = shell.run_check("echo 'SWAPSIZE=0' > /etc/default/haos-swapfile; reboot")
+    # reactivate ShellDriver to handle login again
+    target.deactivate(shell)
+    target.activate(shell)
+    output = shell.run_check("systemctl --no-pager -l list-units --state=failed")
+    assert "0 loaded units listed." in output, f"Some units failed:\n{"\n".join(output)}"
+    swapon = shell.run_check("swapon --show")
+    assert swapon == [], f"Swapfile still exists: {swapon}"
+
+
 @pytest.mark.dependency(depends=["test_init"])
 def test_kernel_not_tainted(shell):
     """Check if the kernel is not tainted - do it at the end of the