From de28dd77c12d67574cc5add467858ef37c518d2b Mon Sep 17 00:00:00 2001
From: Luca Boccassi <bluca@debian.org>
Date: Mon, 5 Dec 2022 12:52:19 +0000
Subject: [PATCH 1/2] test: double default image size

I am now hitting the 500MB limit on Debian stable.
---
 test/test-functions | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/test-functions b/test/test-functions
index 28331c2412..a87b7b966d 100644
--- a/test/test-functions
+++ b/test/test-functions
@@ -1344,7 +1344,7 @@ create_empty_image() {
     fi
 
     # Partition sizes are in MiBs
-    local root_size=500
+    local root_size=1000
     local data_size=50
     if ! get_bool "$NO_BUILD"; then
         if meson configure "${BUILD_DIR:?}" | grep 'static-lib\|standalone-binaries' | awk '{ print $2 }' | grep -q 'true'; then

From 24a4542cfa674ee80b54afcc223f2490a011966b Mon Sep 17 00:00:00 2001
From: Luca Boccassi <bluca@debian.org>
Date: Mon, 5 Dec 2022 21:05:54 +0000
Subject: [PATCH 2/2] pid1: add env var to override default mount rate limit
 burst

I am hitting the rate limit on a busy system with low resources, and
it stalls the boot process which is Very Bad (TM).
---
 docs/ENVIRONMENT.md |  7 +++++++
 src/core/mount.c    | 11 ++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/docs/ENVIRONMENT.md b/docs/ENVIRONMENT.md
index 01ee065583..604d1a6232 100644
--- a/docs/ENVIRONMENT.md
+++ b/docs/ENVIRONMENT.md
@@ -283,6 +283,13 @@ All tools:
   type as unsupported may not prevent loading some units of that type if they
   are referenced by other units of another supported type.
 
+* `$SYSTEMD_DEFAULT_MOUNT_RATE_LIMIT_BURST` — can be set to override the mount
+  units burst rate limit for parsing `/proc/self/mountinfo`. On a system with
+  few resources but many mounts the rate limit may be hit, which will cause the
+  processing of mount units to stall. The burst limit may be adjusted when the
+  default is not appropriate for a given system. Defaults to `5`, accepts
+  positive integers.
+
 `systemd-remount-fs`:
 
 * `$SYSTEMD_REMOUNT_ROOT_RW=1` — if set and no entry for the root directory
diff --git a/src/core/mount.c b/src/core/mount.c
index be46e56689..f16e5c487b 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -1909,6 +1909,7 @@ static void mount_enumerate(Manager *m) {
         mnt_init_debug(0);
 
         if (!m->mount_monitor) {
+                unsigned mount_rate_limit_burst = 5;
                 int fd;
 
                 m->mount_monitor = mnt_new_monitor();
@@ -1948,7 +1949,15 @@ static void mount_enumerate(Manager *m) {
                         goto fail;
                 }
 
-                r = sd_event_source_set_ratelimit(m->mount_event_source, 1 * USEC_PER_SEC, 5);
+                /* Let users override the default (5 in 1s), as it stalls the boot sequence on busy systems. */
+                const char *e = secure_getenv("SYSTEMD_DEFAULT_MOUNT_RATE_LIMIT_BURST");
+                if (e) {
+                        r = safe_atou(e, &mount_rate_limit_burst);
+                        if (r < 0)
+                                log_debug("Invalid value in $SYSTEMD_DEFAULT_MOUNT_RATE_LIMIT_BURST, ignoring: %s", e);
+                }
+
+                r = sd_event_source_set_ratelimit(m->mount_event_source, 1 * USEC_PER_SEC, mount_rate_limit_burst);
                 if (r < 0) {
                         log_error_errno(r, "Failed to enable rate limit for mount events: %m");
                         goto fail;