[PATCH 3/3] ocfs2: use READ_ONCE for lockless jinode reads

[Li Chen]

ocfs2 journal commit callback reads jbd2_inode dirty range fields without
holding journal->j_list_lock.

Use READ_ONCE() for these reads to correct the concurrency assumptions.

Suggested-by: Jan Kara <jack@xxxxxxxx>
Signed-off-by: Li Chen <me@linux.beauty>
---
 fs/ocfs2/journal.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/ocfs2/journal.c b/fs/ocfs2/journal.c
index 85239807dec7..7032284cdbd6 100644
--- a/fs/ocfs2/journal.c
+++ b/fs/ocfs2/journal.c
@@ -902,8 +902,11 @@ int ocfs2_journal_alloc(struct ocfs2_super *osb)
 
 static int ocfs2_journal_submit_inode_data_buffers(struct jbd2_inode *jinode)
 {
-	return filemap_fdatawrite_range(jinode->i_vfs_inode->i_mapping,
-			jinode->i_dirty_start, jinode->i_dirty_end);
+	struct address_space *mapping = jinode->i_vfs_inode->i_mapping;
+	loff_t dirty_start = READ_ONCE(jinode->i_dirty_start);
+	loff_t dirty_end = READ_ONCE(jinode->i_dirty_end);
+
+	return filemap_fdatawrite_range(mapping, dirty_start, dirty_end);
 }
 
 int ocfs2_journal_init(struct ocfs2_super *osb, int *dirty)
-- 
2.52.0