[PATCH 2/3] jbd2: check return value of blkdev_issue_flush() when committing

[guolingxing]

For journals on a separate device, jbd2_commit_transaction() must
flush the file system device before submitting the commit record,
otherwise the transaction may get committed while the ordered data
are still in the device cache.  However the return value of
blkdev_issue_flush() is ignored so if the flush fails, the commit
record is still submitted and fsync() reports success although the
ordered data may have never reached the disk.  After a crash the
journal recovery will consider such transactions committed and data
written by fsync() may be lost.

Abort the journal when the flush fails.  The commit record is then
not submitted anymore since journal_submit_commit_record() checks
for an aborted journal.

Fixes: cc3e1bea5d87 ("ext4, jbd2: Add barriers for file systems with exernal journals")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: guolingxing <guolingxing@xxxxxxxxxx>
---
 fs/jbd2/commit.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 3029cb6f6d64..99477e9c78c7 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -800,8 +800,12 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	 */
 	if ((commit_transaction->t_need_data_flush || update_tail) &&
 	    (journal->j_fs_dev != journal->j_dev) &&
-	    (journal->j_flags & JBD2_BARRIER))
-		blkdev_issue_flush(journal->j_fs_dev);
+	    (journal->j_flags & JBD2_BARRIER)) {
+		int err = blkdev_issue_flush(journal->j_fs_dev);
+
+		if (err)
+			jbd2_journal_abort(journal, err);
+	}
 
 	/* Done it all: now write the commit record asynchronously. */
 	if (jbd2_has_feature_async_commit(journal)) {
-- 
2.34.1