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Date:   Fri, 15 Jul 2022 20:51:52 +0800
From:   Zhihao Cheng <chengzhihao1@...wei.com>
To:     <tytso@....edu>, <jack@...e.com>, <ritesh.list@...il.com>,
        <lczerner@...hat.com>, <akpm@...l.org>, <shaggy@...tin.ibm.com>
CC:     <linux-ext4@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <chengzhihao1@...wei.com>, <yukuai3@...wei.com>
Subject: [PATCH] jbd2: Fix assertion 'jh->b_frozen_data == NULL' failure when journal aborted

Following process will fail assertion 'jh->b_frozen_data == NULL' in
jbd2_journal_dirty_metadata():

                   jbd2_journal_commit_transaction
unlink(dir/a)
 jh->b_transaction = trans1
 jh->b_jlist = BJ_Metadata
                    journal->j_running_transaction = NULL
                    trans1->t_state = T_COMMIT
unlink(dir/b)
 handle->h_trans = trans2
 do_get_write_access
  jh->b_modified = 0
  jh->b_frozen_data = frozen_buffer
  jh->b_next_transaction = trans2
 jbd2_journal_dirty_metadata
  is_handle_aborted
   is_journal_aborted // return false

           --> jbd2 abort <--

                     while (commit_transaction->t_buffers)
                      if (is_journal_aborted)
                       jbd2_journal_refile_buffer
                        __jbd2_journal_refile_buffer
                         WRITE_ONCE(jh->b_transaction,
						jh->b_next_transaction)
                         WRITE_ONCE(jh->b_next_transaction, NULL)
                         __jbd2_journal_file_buffer(jh, BJ_Reserved)
        J_ASSERT_JH(jh, jh->b_frozen_data == NULL) // assertion failure !

The reproducer (See detail in [Link]) reports:
 ------------[ cut here ]------------
 kernel BUG at fs/jbd2/transaction.c:1629!
 invalid opcode: 0000 [#1] PREEMPT SMP
 CPU: 2 PID: 584 Comm: unlink Tainted: G        W
 5.19.0-rc6-00115-g4a57a8400075-dirty #697
 RIP: 0010:jbd2_journal_dirty_metadata+0x3c5/0x470
 RSP: 0018:ffffc90000be7ce0 EFLAGS: 00010202
 Call Trace:
  <TASK>
  __ext4_handle_dirty_metadata+0xa0/0x290
  ext4_handle_dirty_dirblock+0x10c/0x1d0
  ext4_delete_entry+0x104/0x200
  __ext4_unlink+0x22b/0x360
  ext4_unlink+0x275/0x390
  vfs_unlink+0x20b/0x4c0
  do_unlinkat+0x42f/0x4c0
  __x64_sys_unlink+0x37/0x50
  do_syscall_64+0x35/0x80

After journal aborting, __jbd2_journal_refile_buffer() is executed with
holding @jh->b_state_lock, we can fix it by moving 'is_handle_aborted()'
into the area protected by @jh->b_state_lock.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216251
Fixes: 470decc613ab20 ("[PATCH] jbd2: initial copy of files from jbd")
Signed-off-by: Zhihao Cheng <chengzhihao1@...wei.com>
---
 fs/jbd2/transaction.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index e9c308ae475f..e0377f558eb1 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1486,8 +1486,6 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
 	struct journal_head *jh;
 	int ret = 0;
 
-	if (is_handle_aborted(handle))
-		return -EROFS;
 	if (!buffer_jbd(bh))
 		return -EUCLEAN;
 
@@ -1534,6 +1532,18 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
 	journal = transaction->t_journal;
 	spin_lock(&jh->b_state_lock);
 
+	if (is_handle_aborted(handle)) {
+		/*
+		 * Check journal aborting with @jh->b_state_lock locked,
+		 * since 'jh->b_transaction' could be replaced with
+		 * 'jh->b_next_transaction' during old transaction
+		 * committing if journal aborted, which may fail
+		 * assertion on 'jh->b_frozen_data == NULL'.
+		 */
+		ret = -EROFS;
+		goto out_unlock_bh;
+	}
+
 	if (jh->b_modified == 0) {
 		/*
 		 * This buffer's got modified and becoming part
-- 
2.31.1

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