[PATCH] ext4: Initialize fsync transaction ids in ext4_new_inode()

[PATCH] ext4: Initialize fsync transaction ids in ext4_new_inode()

[Theodore Ts'o]

When allocating a new inode, we need to make sure i_sync_tid and
i_datasync_tid are initialized.  Otherwise, one or both of these two
values could be left initialized to zero, which could potentially
result in BUG_ON in jbd2_journal_commit_transaction.

(This could happen by having journal->commit_request getting set to
zero, which could wake up the kjournald process even though there is
no running transaction, which then causes a BUG_ON via the
J_ASSERT(j_ruinning_transaction != NULL) statement.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
 fs/ext4/ialloc.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index 2fd3b0e..a679a48 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -1054,6 +1054,11 @@ got:
 		}
 	}
 
+	if (ext4_handle_valid(handle)) {
+		ei->i_sync_tid = handle->h_transaction->t_tid;
+		ei->i_datasync_tid = handle->h_transaction->t_tid;
+	}
+
 	err = ext4_mark_inode_dirty(handle, inode);
 	if (err) {
 		ext4_std_error(sb, err);
-- 
1.7.3.1