Re: [PATCH] ext4: make online defrag error reporting consistent

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Jun 17, 2015 at 12:40:35PM -0400, Eric Whitney wrote:
> Make the error reporting behavior resulting from the unsupported use
> of online defrag on files with data journaling enabled consistent with
> that implemented for bigalloc file systems. Difference found with
> ext4/308.
> 
> Signed-off-by: Eric Whitney <enwlinux@gmail.com>
> ---
>  fs/ext4/move_extent.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
> index 8c04afb..fb6f117 100644
> --- a/fs/ext4/move_extent.c
> +++ b/fs/ext4/move_extent.c
> @@ -571,12 +571,16 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, __u64 orig_blk,
>  			orig_inode->i_ino, donor_inode->i_ino);
>  		return -EINVAL;
>  	}
> -	/* TODO: This is non obvious task to swap blocks for inodes with full
> -	   jornaling enabled */
> +
> +	/* TODO: it's not obvious how to swap blocks for inodes with full
> +	   journaling enabled */
>  	if (ext4_should_journal_data(orig_inode) ||
>  	    ext4_should_journal_data(donor_inode)) {
> -		return -EINVAL;
> +		ext4_msg(orig_inode->i_sb, KERN_ERR,
> +			 "Online defrag not supported with data journaling");
> +		return -EOPNOTSUPP;
>  	}
> +

One minor nit: If it's solely the donor_inode that's data=journal (i.e. we
didn't mount with data=journal and only the donor inode is chattr +j), the
inode number reported in the message will be inaccurate.

I'm not sure why you'd chattr +j only the donor inode, so in practice this
isn't likely to occur.

Other than that,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

>  	/* Protect orig and donor inodes against a truncate */
>  	lock_two_nondirectories(orig_inode, donor_inode);
>  
> -- 
> 2.1.4
> 
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