[PATCH 6.12.y] ext4: preserve SB_I_VERSION on remount

[Sasha Levin <sashal@kernel.org>]

From: Baokun Li <libaokun1@huawei.com>

[ Upstream commit f2326fd14a224e4cccbab89e14c52279ff79b7ec ]

IMA testing revealed that after an ext4 remount, file accesses triggered
full measurements even without modifications, instead of skipping as
expected when i_version is unchanged.

Debugging showed `SB_I_VERSION` was cleared in reconfigure_super() during
remount due to commit 1ff20307393e ("ext4: unconditionally enable the
i_version counter") removing the fix from commit 960e0ab63b2e ("ext4: fix
i_version handling on remount").

To rectify this, `SB_I_VERSION` is always set for `fc->sb_flags` in
ext4_init_fs_context(), instead of `sb->s_flags` in __ext4_fill_super(),
ensuring it persists across all mounts.

Cc: stable@kernel.org
Fixes: 1ff20307393e ("ext4: unconditionally enable the i_version counter")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250703073903.6952-2-libaokun@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
[ Adjust context ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/ext4/super.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 99117d1e1bdd..cc083eed496a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2019,6 +2019,9 @@ int ext4_init_fs_context(struct fs_context *fc)
 	fc->fs_private = ctx;
 	fc->ops = &ext4_context_ops;
 
+	/* i_version is always enabled now */
+	fc->sb_flags |= SB_I_VERSION;
+
 	return 0;
 }
 
@@ -5277,9 +5280,6 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
 	sb->s_flags = (sb->s_flags & ~SB_POSIXACL) |
 		(test_opt(sb, POSIX_ACL) ? SB_POSIXACL : 0);
 
-	/* i_version is always enabled now */
-	sb->s_flags |= SB_I_VERSION;
-
 	err = ext4_check_feature_compatibility(sb, es, silent);
 	if (err)
 		goto failed_mount;
-- 
2.50.1