Re: [PATCH] xfs: check directory data block header padding in scrub

[Yuto Ohnuki]

On Mon, Apr 06, 2026 at 08:21:10AM -0700, Darrick J. Wong wrote:

Hi Darrick,
Thank you for the review.

> But where do we set xfs_dir3_data_hdr.pad to zero?  xfs_dir3_data_init
> does not seem to do this...

Thank you for pointing that out. I'll fix xfs_dir3_data_init to zero
the full xfs_dir3_data_hdr instead of just xfs_dir3_blk_hdr so that
the pad field is covered by the memset.

> ...and even if there is code that does the zero-initialization, it's
> possible that old kernels wrote out garbage in the pad field and were
> quite ok with that.  At best you can set XFS_SCRUB_OFLAG_PREEN to
> indicate that this kernel should clean it out.
> 
> (For that you'd also want to add a new xchk_fblock_set_corrupt helper to
> record which block tripped the "optimization possible" message.)
> 
> --D
> 

Understood. I'll switch to xchk_fblock_set_preen and add the missing
helper for that.

I'll send a v2 with these changes.

Thanks,
Yuto




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