Re: [PATCH] ext4: Ensure writecache to disk in no journal mode

[Dmitry Monakhov <dmonakhov@openvz.org>]

Surbhi Palande <surbhi.palande@canonical.com> writes:

> Ensure that in the no journal mode the write cache is flushed to the disk by
> calling a blkdev_issue_flush() which issues a WRITE_BARRIER if necessary.
As soon as i understand, nojournal mode is assumed to be used for
fail-free block devices(raid + UPS). So we don't have to worry about
blkdev's wcache vs persistent storage correctness.
>
> Signed-off-by: Surbhi Palande <surbhi.palande@canonical.com>
> ---
>  fs/ext4/fsync.c |    8 ++++++--
>  1 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
> index d6049e4..1d73a50 100644
> --- a/fs/ext4/fsync.c
> +++ b/fs/ext4/fsync.c
> @@ -67,8 +67,12 @@ int ext4_sync_file(struct file *file, struct dentry *dentry, int datasync)
>  	if (ret < 0)
>  		return ret;
>  
> -	if (!journal)
> -		return simple_fsync(file, dentry, datasync);
> +	if (!journal) {
> +		ret = simple_fsync(file, dentry, datasync);
> +		if (test_opt(inode->i_sb, BARRIER))
> +			blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
> +		return ret;
> +	}
>  
>  	/*
>  	 * data=writeback,ordered: