linux-kernel - [PATCH 3.16 126/306] jbd2: fix incorrect unlock on j_list

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Message-ID: <lsq.1487198500.381595262@decadent.org.uk>
Date:   Wed, 15 Feb 2017 22:41:40 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Andreas Dilger" <adilger@...ger.ca>,
        "Taesoo Kim" <tsgatesv@...il.com>, "Theodore Ts'o" <tytso@....edu>
Subject: [PATCH 3.16 126/306] jbd2: fix incorrect unlock on j_list_lock

3.16.40-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Taesoo Kim <tsgatesv@...il.com>

commit 559cce698eaf4ccecb2213b2519ea3a0413e5155 upstream.

When 'jh->b_transaction == transaction' (asserted by below)

  J_ASSERT_JH(jh, (jh->b_transaction == transaction || ...

'journal->j_list_lock' will be incorrectly unlocked, since
the the lock is aquired only at the end of if / else-if
statements (missing the else case).

Signed-off-by: Taesoo Kim <tsgatesv@...il.com>
Signed-off-by: Theodore Ts'o <tytso@....edu>
Reviewed-by: Andreas Dilger <adilger@...ger.ca>
Fixes: 6e4862a5bb9d12be87e4ea5d9a60836ebed71d28
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/jbd2/transaction.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -1093,6 +1093,7 @@ int jbd2_journal_get_create_access(handl
 		JBUFFER_TRACE(jh, "file as BJ_Reserved");
 		spin_lock(&journal->j_list_lock);
 		__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
+		spin_unlock(&journal->j_list_lock);
 	} else if (jh->b_transaction == journal->j_committing_transaction) {
 		/* first access by this transaction */
 		jh->b_modified = 0;
@@ -1100,8 +1101,8 @@ int jbd2_journal_get_create_access(handl
 		JBUFFER_TRACE(jh, "set next transaction");
 		spin_lock(&journal->j_list_lock);
 		jh->b_next_transaction = transaction;
+		spin_unlock(&journal->j_list_lock);
 	}
-	spin_unlock(&journal->j_list_lock);
 	jbd_unlock_bh_state(bh);
 
 	/*