ext4: preserve SB_I_VERSION on remount

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>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9203518786e40230cd42128201e8583ed774fb35..ed1b36bd51c87239814d4dcf57753f0bc781068b 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1998,6 +1998,9 @@ 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;
 }
 
@@ -5316,9 +5319,6 @@ 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;
-
        /* HSM events are allowed by default. */
        sb->s_iflags |= SB_I_ALLOW_HSM;