[PATCH v3 4/5] jbd2: abort journal if free a async write error metadata buffer

["zhangyi (F)" <yi.zhang@huawei.com>]

If we free a metadata buffer which has been failed to async write out
in the background, the jbd2 checkpoint procedure will not detect this
failure in jbd2_log_do_checkpoint(), so it may lead to filesystem
inconsistency after cleanup journal tail. This patch abort the journal
if free a buffer has write_io_error flag to prevent potential further
inconsistency.

Signed-off-by: zhangyi (F) <yi.zhang@huawei.com>
---
 fs/jbd2/transaction.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index e91aad3637a2..a4932e8dcb65 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -2117,6 +2117,7 @@ int jbd2_journal_try_to_free_buffers(journal_t *journal,
 {
 	struct buffer_head *head;
 	struct buffer_head *bh;
+	bool has_write_io_error = false;
 	int ret = 0;
 
 	J_ASSERT(PageLocked(page));
@@ -2141,11 +2142,26 @@ int jbd2_journal_try_to_free_buffers(journal_t *journal,
 		jbd2_journal_put_journal_head(jh);
 		if (buffer_jbd(bh))
 			goto busy;
+
+		/*
+		 * If we free a metadata buffer which has been failed to
+		 * write out, the jbd2 checkpoint procedure will not detect
+		 * this failure and may lead to filesystem inconsistency
+		 * after cleanup journal tail.
+		 */
+		if (buffer_write_io_error(bh)) {
+			pr_err("JBD2: Error while async write back metadata bh %llu.",
+			       (unsigned long long)bh->b_blocknr);
+			has_write_io_error = true;
+		}
 	} while ((bh = bh->b_this_page) != head);
 
 	ret = try_to_free_buffers(page);
 
 busy:
+	if (has_write_io_error)
+		jbd2_journal_abort(journal, -EIO);
+
 	return ret;
 }
 
-- 
2.25.4