Hi, I have looked a bit more into the semantics of the various flags concerning block device caching behaviour. According to "Documentation/block/writeback_cache_control.txt" a call to blkdev_issue_flush() is equivalent to an empty bio with the REQ_FLUSH flag set. So there is no need to call blkdev_issue_flush() after a call to nilfs_commit_super(). But if there is no need to write the super block an additional call to blkdev_issue_flush() is necessary. To avoid an overhead I introduced the THE_NILFS_FLUSHED flag, which is cleared whenever new logs are written and set whenever the block device is flushed. If the super block was written during segment construction or in nilfs_sync_fs(), then blkdev_issue_flush() is not called. I am pretty sure, that there are no race conditions, but maybe someone should check that possibility before merging this. br, Andreas Rohner v1->v2 * Add new flag THE_NILFS_FLUSHED Andreas Rohner (1): nilfs2: add missing blkdev_issue_flush() to nilfs_sync_fs() fs/nilfs2/file.c | 3 ++- fs/nilfs2/ioctl.c | 3 ++- fs/nilfs2/segment.c | 2 ++ fs/nilfs2/super.c | 8 ++++++++ fs/nilfs2/the_nilfs.h | 6 ++++++ 5 files changed, 20 insertions(+), 2 deletions(-) -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-nilfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
