systemd/backport-pid1-add-env-var-to-override-default-mount-rate-limit-burst.patch

65 lines
2.7 KiB
Diff

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] 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).
Signed-off-by: zhaoxiaohu <zhaoxiaohu@kuaishou.com>
---
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 33606fc..4c37e03 100644
--- a/docs/ENVIRONMENT.md
+++ b/docs/ENVIRONMENT.md
@@ -263,6 +263,13 @@ All tools:
`systemd-remount-fs`:
+* `$SYSTEMD_DEFAULT_MOUNT_RATE_LIMIT_BURST` — can be set to override the mount
+ units burst rate limit for parsing `/proc/self/mountinfo`. On a system with
+ few resources but many mounts the rate limit may be hit, which will cause the
+ processing of mount units to stall. The burst limit may be adjusted when the
+ default is not appropriate for a given system. Defaults to `5`, accepts
+ positive integers.
+
* `$SYSTEMD_REMOUNT_ROOT_RW=1` — if set and no entry for the root directory
exists in `/etc/fstab` (this file always takes precedence), then the root
directory is remounted writable. This is primarily used by
diff --git a/src/core/mount.c b/src/core/mount.c
index 11327d4..ead9b46 100644
--- a/src/core/mount.c
+++ b/src/core/mount.c
@@ -1875,6 +1875,7 @@ 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();
@@ -1914,7 +1915,15 @@ 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;
--
2.33.0