[PATCH 2/2] ext4: Add fdatasync scalability optimization

Track blkdev's flush generation counter on per-inode basis and update inside end_io. If inode's flush generation counter is older than current blkdev's flush counter inode's data was already flushed to stable media, so we can skip explicit barrier. Optimization is safe only when inode's end_io was

[PATCH 2/2] ext4: Add fdatasync scalability optimization

Track blkdev's flush generation counter on per-inode basis and update inside end_io. If inode's flush generation counter is older than current blkdev's flush counter inode's data was already flushed to stable media, so we can skip explicit barrier. Optimization is safe only when inode's end_io was