ext4: Wait for proper transaction commit on fsync

We cannot rely on buffer dirty bits during fsync because pdflush can come
before fsync is called and clear dirty bits without forcing a transaction
commit. What we do is that we track which transaction has last changed
the inode and which transaction last changed allocation and force it to
disk on fsync.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 13 insertions, 0 deletions

diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 2c2b262bd31b..05eca817d704 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -249,6 +249,19 @@ static inline int ext4_jbd2_file_inode(handle_t *handle, struct inode *inode)
         return 0;
 }
 
+static inline void ext4_update_inode_fsync_trans(handle_t *handle,
+                                                 struct inode *inode,
+                                                 int datasync)
+{
+        struct ext4_inode_info *ei = EXT4_I(inode);
+
+        if (ext4_handle_valid(handle)) {
+                ei->i_sync_tid = handle->h_transaction->t_tid;
+                if (datasync)
+                        ei->i_datasync_tid = handle->h_transaction->t_tid;
+        }
+}
+
 /* super.c */
 int ext4_force_commit(struct super_block *sb);