mount: optimize mountinfo traversal by decoupling device discovery

backport-mount-optimize-mountinfo-traversal-by-decoupling-dev.patch

@@ -0,0 +1,50 @@
+From 00ad3f02275b507a753495ace5e5f84cb38b604d Mon Sep 17 00:00:00 2001
+From: Chen Guanqiao <chen.chenchacha@foxmail.com>
+Date: Wed, 2 Oct 2024 13:10:21 +0800
+Subject: [PATCH] mount: optimize mountinfo traversal by decoupling device
+ discovery
+
+In mount_load_proc_self_mountinfo(), device_found_node() is synchronously called
+during the traversal of mountinfo entries. When there are a large number of
+mount points, and the device types are not significantly different, this results
+in excessive time consumption during device discovery, causing a performance
+bottleneck. This issue is particularly prominent on servers with a large number
+of cores in IDC.
+
+This patch decouples device discovery from the mountinfo traversal process,
+avoiding redundant device operations. As a result, it significantly improves
+performance, especially in environments with numerous mount points.
+
+Signed-off-by: Chen Guanqiao <chen.chenchacha@foxmail.com>
+---
+ src/core/mount.c | 7 ++++++-
+ 1 file changed, 6 insertions(+), 1 deletion(-)
+
+diff --git a/src/core/mount.c b/src/core/mount.c
+index 28701df231..5261b80957 100644
+--- a/src/core/mount.c
++++ b/src/core/mount.c
+@@ -1857,6 +1857,7 @@ static int mount_setup_unit(
+ static int mount_load_proc_self_mountinfo(Manager *m, bool set_flags) {
+         _cleanup_(mnt_free_tablep) struct libmnt_table *table = NULL;
+         _cleanup_(mnt_free_iterp) struct libmnt_iter *iter = NULL;
++        _cleanup_set_free_ Set *devices = NULL;
+         int r;
+ 
+         assert(m);
+@@ -1883,7 +1884,11 @@ static int mount_load_proc_self_mountinfo(Manager *m, bool set_flags) {
+                 if (!device || !path)
+                         continue;
+ 
+-                device_found_node(m, device, DEVICE_FOUND_MOUNT, DEVICE_FOUND_MOUNT);
++                /* Just to achieve device name uniqueness. Note that the suppresion of the duplicate
++                 * processing is merely an optimization, hence in case of OOM (unlikely) we'll just process
++                 * it twice. */
++                if (set_put_strdup_full(&devices, &path_hash_ops_free, device) != 0)
++                        device_found_node(m, device, DEVICE_FOUND_MOUNT, DEVICE_FOUND_MOUNT);
+ 
+                 (void) mount_setup_unit(m, device, path, options, fstype, set_flags);
+         }
+-- 
+2.33.0
+

systemd.spec

@@ -25,7 +25,7 @@
 Name:           systemd
 Url:            https://systemd.io/
 Version:        255
-Release:        22
+Release:        23
 License:        MIT and LGPLv2+ and GPLv2+
 Summary:        System and Service Manager
 
@@ -66,9 +66,10 @@ Patch6012:      backport-unit-check-for-correct-function-in-vtable.patch
 Patch6013:      backport-fix-homed-log-message-typo-error.patch
 Patch6014:      backport-bash-completion-add-systemctl-service-log-level-target.patch
 Patch6015:      backport-fix-log-message-not-match-glob-patterns-passed-to-disable-command.patch
-Patch6016:	backport-main-pass-the-right-error-variable.patch
+Patch6016:      backport-main-pass-the-right-error-variable.patch
-Patch6017:  	backport-sd-event-fix-fd-leak-when-fd-is-owned-by-IO-event-source.patch
+Patch6017:      backport-sd-event-fix-fd-leak-when-fd-is-owned-by-IO-event-source.patch
-Patch6018:  	backport-fix-cgtop-sscanf-return-code-checks.patch
+Patch6018:      backport-fix-cgtop-sscanf-return-code-checks.patch
+Patch6019:      backport-mount-optimize-mountinfo-traversal-by-decoupling-dev.patch
 
 Patch9008:      update-rtc-with-system-clock-when-shutdown.patch
 Patch9009:      udev-add-actions-while-rename-netif-failed.patch
@@ -1658,6 +1659,9 @@ fi
 %{_unitdir}/veritysetup.target
 
 %changelog
+* Tue Nov 05 2024 xujing <xujing125@huawei.com> - 255-23
+- DESC:optimize mountinfo traversal by decoupling device discovery
+
 * Mon Sep 23 2024 xujing <xujing125@huawei.com> - 255-22
 - DESC:fix cgroup v2 cpuset function error and optimize the code of cpuset and freezer