From 99299d0d5a722812cedc0a23e4987f90a257c2d2 Mon Sep 17 00:00:00 2001
From: Mike Yuan <me@yhndnzj.com>
Date: Wed, 26 Jul 2023 12:04:07 +0800
Subject: [PATCH 1/2] fstab-util: add fstab_is_mount_point_full which takes a
 source path to compare

---
 src/shared/fstab-util.c | 42 +++++++++++++++++++++++++++++++++++------
 src/shared/fstab-util.h |  6 +++++-
 2 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/src/shared/fstab-util.c b/src/shared/fstab-util.c
index 6efdcd6896..4ffec25c75 100644
--- a/src/shared/fstab-util.c
+++ b/src/shared/fstab-util.c
@@ -63,23 +63,53 @@ bool fstab_is_extrinsic(const char *mount, const char *opts) {
         return false;
 }
 
-int fstab_is_mount_point(const char *mount) {
+static int fstab_is_mount_point_of(const char *what_fstab, const char *path) {
+        _cleanup_free_ char *node = NULL;
+
+        assert(what_fstab);
+        assert(path);
+
+        node = fstab_node_to_udev_node(what_fstab);
+        if (!node)
+                return -ENOMEM;
+
+        if (path_equal(node, path))
+                return true;
+
+        if (is_device_node(path) && is_device_node(node))
+                return devnode_same(node, path);
+
+        return false;
+}
+
+int fstab_is_mount_point_full(const char *where, const char *path) {
         _cleanup_endmntent_ FILE *f = NULL;
-        struct mntent *m;
+        int r;
+
+        assert(where);
 
         f = setmntent(fstab_path(), "re");
         if (!f)
                 return errno == ENOENT ? false : -errno;
 
         for (;;) {
+                struct mntent *me;
+
                 errno = 0;
-                m = getmntent(f);
-                if (!m)
+                me = getmntent(f);
+                if (!me)
                         return errno != 0 ? -errno : false;
 
-                if (path_equal(m->mnt_dir, mount))
-                        return true;
+                if (path_equal(where, me->mnt_dir)) {
+                        if (!path)
+                                return true;
+
+                        r = fstab_is_mount_point_of(me->mnt_fsname, path);
+                        if (r > 0 || (r < 0 && !ERRNO_IS_DEVICE_ABSENT(r)))
+                                return r;
+                }
         }
+
         return false;
 }
 
diff --git a/src/shared/fstab-util.h b/src/shared/fstab-util.h
index 5979b476b6..cb3686bee3 100644
--- a/src/shared/fstab-util.h
+++ b/src/shared/fstab-util.h
@@ -7,9 +7,13 @@
 #include "macro.h"
 
 bool fstab_is_extrinsic(const char *mount, const char *opts);
-int fstab_is_mount_point(const char *mount);
 int fstab_has_fstype(const char *fstype);
 
+int fstab_is_mount_point_full(const char *where, const char *path);
+static inline int fstab_is_mount_point(const char *where) {
+        return fstab_is_mount_point_full(where, NULL);
+}
+
 int fstab_filter_options(
                 const char *opts,
                 const char *names,

From 69d7f35ce4b642910575a3d973e713a27285663d Mon Sep 17 00:00:00 2001
From: Mike Yuan <me@yhndnzj.com>
Date: Wed, 26 Jul 2023 12:10:43 +0800
Subject: [PATCH 2/2] gpt-auto: skip mounting ESP if fstab for /boot/ uses the
 same device as discovered one

Follow-up for 6a488fa7cce8124fa885adf8a2f31363fe62f636

Currently, if an fstab entry for /boot/ exists, we'll skip to try /efi/
instead. However, if it's already using the same device as the discovered
one, we should not duplicate the mount.
---
 src/gpt-auto-generator/gpt-auto-generator.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/gpt-auto-generator/gpt-auto-generator.c b/src/gpt-auto-generator/gpt-auto-generator.c
index 08338bdd93..840d3b6ed1 100644
--- a/src/gpt-auto-generator/gpt-auto-generator.c
+++ b/src/gpt-auto-generator/gpt-auto-generator.c
@@ -590,6 +590,16 @@ static int add_partition_esp(DissectedPartition *p, bool has_xbootldr) {
                                 esp_path = "/boot";
                                 id = "boot";
                         }
+                } else {
+                        /* Check if the fstab entry for /boot/ is already the ESP. If so, we don't need to
+                         * check /efi/ or duplicate the mount there. */
+                        r = fstab_is_mount_point_full("/boot", p->node);
+                        if (r < 0)
+                                return log_error_errno(r,
+                                                       "Failed to check if fstab entry for /boot uses the same device as '%s': %m",
+                                                       p->node);
+                        if (r > 0)
+                                return 0;
                 }
         }