Re: [PATCH v2 22/50] convert efivarfs

[Christian Brauner <brauner@kernel.org>]

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> > > And suspend/resume works just fine with freeze/thaw. See commit
> > > eacfbf74196f ("power: freeze filesystems during suspend/resume")
> > > which implements exactly that.
> > > 
> > > The reason this didn't work for you is very likely:
> > > 
> > > cat /sys/power/freeze_filesystems
> > > 0
> > > 
> > > which you must set to 1.
> > 
> > Actually, no, that's not correct.  The efivarfs freeze/thaw logic must
> > run unconditionally regardless of this setting to fix the systemd bug,
> > so all the variable resyncing is done in the thaw call, which isn't
> > conditioned on the above (or at least it shouldn't be).
> 
> It is conditioned on the above currently but we can certainly fix it
> easily to not be.

Something like the appended patch would do it.

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From 1f9dc293cebb10b18d9ec8e01b60c014664c98ab Mon Sep 17 00:00:00 2001
From: Christian Brauner <brauner@kernel.org>
Date: Wed, 5 Nov 2025 14:39:45 +0100
Subject: [PATCH] power: always freeze efivarfs

The efivarfs filesystems must always be frozen and thawed to resync
variable state. Make it so.

Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 fs/efivarfs/super.c      |  1 +
 fs/super.c               | 14 +++++++++++---
 include/linux/fs.h       |  3 ++-
 kernel/power/hibernate.c |  9 +++------
 kernel/power/suspend.c   |  3 +--
 5 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/fs/efivarfs/super.c b/fs/efivarfs/super.c
index 1f4d8ce56667..6f9cd18ce6f0 100644
--- a/fs/efivarfs/super.c
+++ b/fs/efivarfs/super.c
@@ -512,6 +512,7 @@ static int efivarfs_init_fs_context(struct fs_context *fc)
 	sfi->mount_opts.gid = GLOBAL_ROOT_GID;
 
 	fc->s_fs_info = sfi;
+	fc->s_iflags |= SB_I_FREEZE_POWER;
 	fc->ops = &efivarfs_context_ops;
 
 	return 0;
diff --git a/fs/super.c b/fs/super.c
index 5bab94fb7e03..017f0be22c61 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1183,11 +1183,19 @@ static inline bool get_active_super(struct super_block *sb)
 
 static const char *filesystems_freeze_ptr = "filesystems_freeze";
 
-static void filesystems_freeze_callback(struct super_block *sb, void *unused)
+static void filesystems_freeze_callback(struct super_block *sb, void *bool_freeze_all)
 {
+	bool freeze_all = *(bool *)bool_freeze_all;
+
 	if (!sb->s_op->freeze_fs && !sb->s_op->freeze_super)
 		return;
 
+	if (!freeze_all) {
+		if (!(sb->s_iflags & SB_I_FREEZE_POWER))
+			return;
+		pr_info("VFS: Freezing %s filesystems\n", sb->s_type->name);
+	}
+
 	if (!get_active_super(sb))
 		return;
 
@@ -1201,9 +1209,9 @@ static void filesystems_freeze_callback(struct super_block *sb, void *unused)
 	deactivate_super(sb);
 }
 
-void filesystems_freeze(void)
+void filesystems_freeze(bool freeze_all)
 {
-	__iterate_supers(filesystems_freeze_callback, NULL,
+	__iterate_supers(filesystems_freeze_callback, &freeze_all,
 			 SUPER_ITER_UNLOCKED | SUPER_ITER_REVERSE);
 }
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c895146c1444..bde4967fdb68 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1419,6 +1419,7 @@ extern int send_sigurg(struct file *file);
 #define SB_I_NOUMASK	0x00001000	/* VFS does not apply umask */
 #define SB_I_NOIDMAP	0x00002000	/* No idmapped mounts on this superblock */
 #define SB_I_ALLOW_HSM	0x00004000	/* Allow HSM events on this superblock */
+#define SB_I_FREEZE_POWER	0x00008000	/* Always freeze on suspend/hibernate */
 
 /* Possible states of 'frozen' field */
 enum {
@@ -3606,7 +3607,7 @@ extern void drop_super_exclusive(struct super_block *sb);
 extern void iterate_supers(void (*f)(struct super_block *, void *), void *arg);
 extern void iterate_supers_type(struct file_system_type *,
 			        void (*)(struct super_block *, void *), void *);
-void filesystems_freeze(void);
+void filesystems_freeze(bool freeze_all);
 void filesystems_thaw(void);
 
 extern int dcache_dir_open(struct inode *, struct file *);
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 14e85ff23551..1f250ce036a0 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -825,8 +825,7 @@ int hibernate(void)
 		goto Restore;
 
 	ksys_sync_helper();
-	if (filesystem_freeze_enabled)
-		filesystems_freeze();
+	filesystems_freeze(filesystem_freeze_enabled);
 
 	error = freeze_processes();
 	if (error)
@@ -932,8 +931,7 @@ int hibernate_quiet_exec(int (*func)(void *data), void *data)
 	if (error)
 		goto restore;
 
-	if (filesystem_freeze_enabled)
-		filesystems_freeze();
+	filesystems_freeze(filesystem_freeze_enabled);
 
 	error = freeze_processes();
 	if (error)
@@ -1083,8 +1081,7 @@ static int software_resume(void)
 	if (error)
 		goto Restore;
 
-	if (filesystem_freeze_enabled)
-		filesystems_freeze();
+	filesystems_freeze(filesystem_freeze_enabled);
 
 	pm_pr_dbg("Preparing processes for hibernation restore.\n");
 	error = freeze_processes();
diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c
index 4bb4686c1c08..c933a63a9718 100644
--- a/kernel/power/suspend.c
+++ b/kernel/power/suspend.c
@@ -375,8 +375,7 @@ static int suspend_prepare(suspend_state_t state)
 	if (error)
 		goto Restore;
 
-	if (filesystem_freeze_enabled)
-		filesystems_freeze();
+	filesystems_freeze(filesystem_freeze_enabled);
 	trace_suspend_resume(TPS("freeze_processes"), 0, true);
 	error = suspend_freeze_processes();
 	trace_suspend_resume(TPS("freeze_processes"), 0, false);
-- 
2.47.3