All of lore.kernel.org
 help / color / mirror / Atom feed
* FAILED: patch "[PATCH] jbd2: fix the inconsistency between checksum and data in" failed to apply to 6.6-stable tree
@ 2025-12-29 12:23 gregkh
  2025-12-29 23:40 ` [PATCH 6.6.y] jbd2: fix the inconsistency between checksum and data in memory for journal sb Sasha Levin
  0 siblings, 1 reply; 2+ messages in thread
From: gregkh @ 2025-12-29 12:23 UTC (permalink / raw)
  To: yebin10, djwong, jack, libaokun1, tytso; +Cc: stable


The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 6abfe107894af7e8ce3a2e120c619d81ee764ad5
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025122901-exciting-strained-363f@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6abfe107894af7e8ce3a2e120c619d81ee764ad5 Mon Sep 17 00:00:00 2001
From: Ye Bin <yebin10@huawei.com>
Date: Mon, 3 Nov 2025 09:01:23 +0800
Subject: [PATCH] jbd2: fix the inconsistency between checksum and data in
 memory for journal sb

Copying the file system while it is mounted as read-only results in
a mount failure:
[~]# mkfs.ext4 -F /dev/sdc
[~]# mount /dev/sdc -o ro /mnt/test
[~]# dd if=/dev/sdc of=/dev/sda bs=1M
[~]# mount /dev/sda /mnt/test1
[ 1094.849826] JBD2: journal checksum error
[ 1094.850927] EXT4-fs (sda): Could not load journal inode
mount: mount /dev/sda on /mnt/test1 failed: Bad message

The process described above is just an abstracted way I came up with to
reproduce the issue. In the actual scenario, the file system was mounted
read-only and then copied while it was still mounted. It was found that
the mount operation failed. The user intended to verify the data or use
it as a backup, and this action was performed during a version upgrade.
Above issue may happen as follows:
ext4_fill_super
 set_journal_csum_feature_set(sb)
  if (ext4_has_metadata_csum(sb))
   incompat = JBD2_FEATURE_INCOMPAT_CSUM_V3;
  if (test_opt(sb, JOURNAL_CHECKSUM)
   jbd2_journal_set_features(sbi->s_journal, compat, 0, incompat);
    lock_buffer(journal->j_sb_buffer);
    sb->s_feature_incompat  |= cpu_to_be32(incompat);
    //The data in the journal sb was modified, but the checksum was not
      updated, so the data remaining in memory has a mismatch between the
      data and the checksum.
    unlock_buffer(journal->j_sb_buffer);

In this case, the journal sb copied over is in a state where the checksum
and data are inconsistent, so mounting fails.
To solve the above issue, update the checksum in memory after modifying
the journal sb.

Fixes: 4fd5ea43bc11 ("jbd2: checksum journal superblock")
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Message-ID: <20251103010123.3753631-1-yebin@huaweicloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 2fe1786a8f1b..c973162d5b31 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -2354,6 +2354,12 @@ int jbd2_journal_set_features(journal_t *journal, unsigned long compat,
 	sb->s_feature_compat    |= cpu_to_be32(compat);
 	sb->s_feature_ro_compat |= cpu_to_be32(ro);
 	sb->s_feature_incompat  |= cpu_to_be32(incompat);
+	/*
+	 * Update the checksum now so that it is valid even for read-only
+	 * filesystems where jbd2_write_superblock() doesn't get called.
+	 */
+	if (jbd2_journal_has_csum_v2or3(journal))
+		sb->s_checksum = jbd2_superblock_csum(sb);
 	unlock_buffer(journal->j_sb_buffer);
 	jbd2_journal_init_transaction_limits(journal);
 
@@ -2383,9 +2389,17 @@ void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
 
 	sb = journal->j_superblock;
 
+	lock_buffer(journal->j_sb_buffer);
 	sb->s_feature_compat    &= ~cpu_to_be32(compat);
 	sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
 	sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
+	/*
+	 * Update the checksum now so that it is valid even for read-only
+	 * filesystems where jbd2_write_superblock() doesn't get called.
+	 */
+	if (jbd2_journal_has_csum_v2or3(journal))
+		sb->s_checksum = jbd2_superblock_csum(sb);
+	unlock_buffer(journal->j_sb_buffer);
 	jbd2_journal_init_transaction_limits(journal);
 }
 EXPORT_SYMBOL(jbd2_journal_clear_features);


^ permalink raw reply related	[flat|nested] 2+ messages in thread
end of thread, other threads:[~2025-12-29 23:41 UTC | newest]

Thread overview: 2+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-12-29 12:23 FAILED: patch "[PATCH] jbd2: fix the inconsistency between checksum and data in" failed to apply to 6.6-stable tree gregkh
2025-12-29 23:40 ` [PATCH 6.6.y] jbd2: fix the inconsistency between checksum and data in memory for journal sb Sasha Levin

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.