Improve comments in jbd2_journal_commit_transaction() to describe why
we don't need to clear the buffer_mapped bit for freeing file mapping
buffers whose page mapping is NULL.
Fixes: c96dceeabf76 ("jbd2: do not clear the BH_Mapped flag when forgetting a metadata buffer")
Signed-off-by: zhangyi (F) <yi.zhang@xxxxxxxxxx>
Suggested-by: Jan Kara <jack@xxxxxxx>
---
fs/jbd2/commit.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 27373f5792a4..e855d8260433 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -997,9 +997,10 @@ void jbd2_journal_commit_transaction(journal_t *journal)
* journalled data) we need to unmap buffer and clear
* more bits. We also need to be careful about the check
* because the data page mapping can get cleared under
- * out hands, which alse need not to clear more bits
- * because the page and buffers will be freed and can
- * never be reused once we are done with them.
+ * our hands. Note that if mapping == NULL, we don't
+ * need to make buffer unmapped because the page is
+ * already detached from the mapping and buffers cannot
+ * get reused.
*/
mapping = READ_ONCE(bh->b_page->mapping);
if (mapping && !sb_is_blkdev_sb(mapping->host->i_sb)) {
--
2.17.2
