linux-ext4 - [PATCH 2/2] ext4: preserve SB_I

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Message-Id: <20250703073903.6952-2-libaokun@huaweicloud.com>
Date: Thu,  3 Jul 2025 15:39:03 +0800
From: libaokun@...weicloud.com
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu,
	adilger.kernel@...ger.ca,
	jack@...e.cz,
	linux-kernel@...r.kernel.org,
	yi.zhang@...wei.com,
	yangerkun@...wei.com,
	libaokun1@...wei.com,
	libaokun@...weicloud.com
Subject: [PATCH 2/2] ext4: preserve SB_I_VERSION on remount

From: Baokun Li <libaokun1@...wei.com>

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.

Fixes: 1ff20307393e ("ext4: unconditionally enable the i_version counter")
Signed-off-by: Baokun Li <libaokun1@...wei.com>
---
 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 9203518786e4..ed1b36bd51c8 100644
--- 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;

-- 
2.46.1