From a428a4518b7adaae282cf9f1e623a44d4c7191df Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 5 Nov 2021 15:24:58 +0100
Subject: [PATCH 1/3] homework: default to btrfs compression

This follows what Fedora did with 34: enables compression by default,
lowering IO bandwidth and reducing disk space use, at the price of
slightly higher CPU use.

https://fedoraproject.org/wiki/Changes/BtrfsTransparentCompression
---
 src/home/homework-mount.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/home/homework-mount.c b/src/home/homework-mount.c
index 82b461a987..d73a908f1c 100644
--- a/src/home/homework-mount.c
+++ b/src/home/homework-mount.c
@@ -25,7 +25,7 @@ static const char *mount_options_for_fstype(const char *fstype) {
         if (streq(fstype, "xfs"))
                 return "noquota";
         if (streq(fstype, "btrfs"))
-                return "noacl";
+                return "noacl,compress=zstd:1";
         return NULL;
 }
 

From 6309512c0239bd2c78b099c185b38c15fd096153 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 5 Nov 2021 15:26:29 +0100
Subject: [PATCH 2/3] homed: add env var for overriding default mount options

This adds an esay way to override the default mount options to use for
LUKS home dirs via the env vars SYSTEMD_HOME_MOUNT_OPTIONS_EXT4,
SYSTEMD_HOME_MOUNT_OPTIONS_BTRFS, SYSTEMD_HOME_MOUNT_OPTIONS_XFS.

See: #15120
---
 src/home/homework-mount.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/home/homework-mount.c b/src/home/homework-mount.c
index d73a908f1c..234b965dc8 100644
--- a/src/home/homework-mount.c
+++ b/src/home/homework-mount.c
@@ -20,6 +20,17 @@
 #include "user-util.h"
 
 static const char *mount_options_for_fstype(const char *fstype) {
+        const char *e;
+        char *n;
+
+        assert(fstype);
+
+        /* Allow overriding our built-in defaults with an environment variable */
+        n = strjoina("SYSTEMD_HOME_MOUNT_OPTIONS_", fstype);
+        e = getenv(ascii_strupper(n));
+        if (e)
+                return e;
+
         if (streq(fstype, "ext4"))
                 return "noquota,user_xattr";
         if (streq(fstype, "xfs"))

From db42f011c6302dd2012b3f46c0ced31de12b5051 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Fri, 12 Nov 2021 17:36:53 +0100
Subject: [PATCH 3/3] docs: document new mount option env var

---
 docs/ENVIRONMENT.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/docs/ENVIRONMENT.md b/docs/ENVIRONMENT.md
index 2c61935b6b..5f783ed915 100644
--- a/docs/ENVIRONMENT.md
+++ b/docs/ENVIRONMENT.md
@@ -433,3 +433,9 @@ SYSTEMD_HOME_DEBUG_SUFFIX=foo \
       SYSTEMD_HOME_RECORD_DIR=/var/lib/systemd/home.foo/ \
       /home/lennart/projects/systemd/build/systemd-homed
 ```
+
+* `$SYSTEMD_HOME_MOUNT_OPTIONS_BTRFS`, `$SYSTEMD_HOME_MOUNT_OPTIONS_EXT4`,
+  `$SYSTEMD_HOME_MOUNT_OPTIONS_XFS` – configure the default mount options to
+  use for LUKS home directories, overriding the built-in default mount
+  options. There's one variable for each of the supported file systems for the
+  LUKS home directory backend.