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Re: [PATCH 1/3] xfsprog: add xfs sb v4 support for dirent filetype field

To: Mark Tinguely <tinguely@xxxxxxx>
Subject: Re: [PATCH 1/3] xfsprog: add xfs sb v4 support for dirent filetype field
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Fri, 20 Sep 2013 08:52:43 +1000
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20130919211539.028138471@xxxxxxx>
References: <20130919211523.407741285@xxxxxxx> <20130919211539.028138471@xxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Thu, Sep 19, 2013 at 04:05:24PM -0500, Mark Tinguely wrote:
> Add xfsprog superblock v4 support for the directory inode type
> in xfs_sb.h.
> 
> This support adds a feature bit for version 4 superblocks and
> leaves the original superblock 5 incompatibility bit.
> 
> Signed-off-by: Mark Tinguely <tinguely@xxxxxxx>
> ---
> include/xfs_sb.h |   20 ++++++++++++--------
>  include/xfs_sb.h |   10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> Index: b/include/xfs_sb.h
> ===================================================================
> --- a/include/xfs_sb.h
> +++ b/include/xfs_sb.h
> @@ -84,11 +84,13 @@ struct xfs_trans;
>  #define XFS_SB_VERSION2_PARENTBIT    0x00000010      /* parent pointers */
>  #define XFS_SB_VERSION2_PROJID32BIT  0x00000080      /* 32 bit project id */
>  #define XFS_SB_VERSION2_CRCBIT               0x00000100      /* metadata 
> CRCs */
> +#define XFS_SB_VERSION2_FTYPE                0x00000200      /* inode type 
> in dir */
>  
>  #define      XFS_SB_VERSION2_OKREALFBITS     \
>       (XFS_SB_VERSION2_LAZYSBCOUNTBIT | \
>        XFS_SB_VERSION2_ATTR2BIT       | \
> -      XFS_SB_VERSION2_PROJID32BIT)
> +      XFS_SB_VERSION2_PROJID32BIT    | \
> +      XFS_SB_VERSION2_FTYPE)
>  #define      XFS_SB_VERSION2_OKSASHFBITS     \
>       (0)
>  #define XFS_SB_VERSION2_OKREALBITS   \
> @@ -631,8 +633,10 @@ static inline int xfs_sb_version_has_pqu
>  
>  static inline int xfs_sb_version_hasftype(struct xfs_sb *sbp)
>  {
> -     return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
> -             xfs_sb_has_incompat_feature(sbp, XFS_SB_FEAT_INCOMPAT_FTYPE);
> +     return (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
> +             xfs_sb_has_incompat_feature(sbp, XFS_SB_FEAT_INCOMPAT_FTYPE)) ||
> +            (xfs_sb_version_hasmorebits(sbp) &&
> +              (sbp->sb_features2 & XFS_SB_VERSION2_FTYPE));

This is kinda inefficient. Seeing as I didn't review the kernel
version, I'll review it now. Expand it out:

        return (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 &&
                xfs_sb_has_incompat_feature(sbp, XFS_SB_FEAT_INCOMPAT_FTYPE)) ||
               ((XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5) ||
                (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_4 &&
                (sbp->sb_versionnum & XFS_SB_VERSION_MOREBITSBIT))) &&
               (sbp->sb_features2 & XFS_SB_VERSION2_FTYPE));
        

so, really, the check could be refined to:

        return XFS_SB_VERSION_NUM(sbp) >= XFS_SB_VERSION_4 &&
               (xfs_sb_has_incompat_feature(sbp, XFS_SB_FEAT_INCOMPAT_FTYPE) ||
                ((sbp->sb_versionnum & XFS_SB_VERSION_MOREBITSBIT) &&
                 (sbp->sb_features2 & XFS_SB_VERSION2_FTYPE)));

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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