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From: Zhang Yi <yi.zhang@huawei.com>
To: <linux-ext4@vger.kernel.org>
Cc: <tytso@mit.edu>, <adilger.kernel@dilger.ca>, <jack@suse.cz>,
	<yi.zhang@huawei.com>, <yukuai3@huawei.com>
Subject: [PATCH 1/3] jbd2: protect buffers release with j_checkpoint_mutex
Date: Thu, 8 Apr 2021 19:36:16 +0800
Message-ID: <20210408113618.1033785-2-yi.zhang@huawei.com> (raw)
In-Reply-To: <20210408113618.1033785-1-yi.zhang@huawei.com>

There is a race between jbd2_journal_try_to_free_buffers() and
jbd2_journal_destroy(), so the jbd2_log_do_checkpoint() may still
missing to detect the buffer write io error flag and lead to filesystem
inconsistency.

jbd2_journal_try_to_free_buffers()     ext4_put_super()
                                        jbd2_journal_destroy()
  __jbd2_journal_remove_checkpoint()
  detect buffer write error              jbd2_log_do_checkpoint()
                                         jbd2_cleanup_journal_tail()
                                           <--- lead to inconsistency
  jbd2_journal_abort()

Fix this issue by add j_checkpoint_mutex to protect journal buffer
release on jbd2_journal_try_to_free_buffers().

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
 fs/jbd2/transaction.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 9396666b7314..b935b20cbae4 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -2123,6 +2123,7 @@ int jbd2_journal_try_to_free_buffers(journal_t *journal, struct page *page)
 
 	J_ASSERT(PageLocked(page));
 
+	mutex_lock(&journal->j_checkpoint_mutex);
 	head = page_buffers(page);
 	bh = head;
 	do {
@@ -2163,6 +2164,7 @@ int jbd2_journal_try_to_free_buffers(journal_t *journal, struct page *page)
 	if (has_write_io_error)
 		jbd2_journal_abort(journal, -EIO);
 
+	mutex_unlock(&journal->j_checkpoint_mutex);
 	return ret;
 }
 
-- 
2.25.4


  reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-08 11:36 [PATCH 0/3] ext4: fix two issue about bdev_try_to_free_page() Zhang Yi
2021-04-08 11:36 ` Zhang Yi [this message]
2021-04-08 13:45   ` [PATCH 1/3] jbd2: protect buffers release with j_checkpoint_mutex Jan Kara
2021-04-08 11:36 ` [PATCH 2/3] jbd2: do not free buffers in jbd2_journal_try_to_free_buffers() Zhang Yi
2021-04-08 11:36 ` [PATCH 3/3] ext4: add rcu to prevent use after free when umount filesystem Zhang Yi
2021-04-08 13:51   ` kernel test robot
2021-04-08 13:56   ` Jan Kara
2021-04-08 14:38     ` Zhang Yi
2021-04-08 14:53       ` Jan Kara

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