On Fri, Jul 02, 2021 at 07:57:55PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@xxxxxxxxxx>
>
> Extent size hints exist to nudge the behavior of the file data block
> allocator towards trying to make aligned allocations. Therefore, it
> doesn't make sense to allow a hint that isn't a multiple of the
> fundamental allocation unit for a given file.
>
> This means that if the sysadmin is formatting with rtinherit set on the
> root dir, validate_extsize_hint needs to check the hint value on a
> simulated realtime file to make sure that it's correct. Unfortunately,
> the gate check here was for a nonzero rt extent size, which is wrong
> since we never format with rtextsize==0. This leads to absurd failures
> such as:
Reviewed-by: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
>
> # mkfs.xfs -f /dev/sdf -r extsize=7b -d rtinherit=0,extszinherit=13
> illegal extent size hint 13, must be less than 649088 and a multiple of 7.
>
> Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> ---
> mkfs/xfs_mkfs.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
>
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index f84a42f9..9c14c04e 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -2384,10 +2384,11 @@ _("illegal extent size hint %lld, must be less than %u.\n"),
> }
>
> /*
> - * Now we do it again with a realtime file so that we know the hint and
> - * flag that get passed on to realtime files will be correct.
> + * If the value is to be passed on to realtime files, revalidate with
> + * a realtime file so that we know the hint and flag that get passed on
> + * to realtime files will be correct.
> */
> - if (mp->m_sb.sb_rextsize == 0)
> + if (!(cli->fsx.fsx_xflags & FS_XFLAG_RTINHERIT))
> return;
>
> flags = XFS_DIFLAG_REALTIME;
>
--
Carlos
