On Thu, Jul 24, 2014 at 10:23:00AM -0400, Brian Foster wrote:
> The sparse chunk inode record format is backwards compatible with old
> format inobt records as long as full chunks are allocated. The holemask
> field uses higher order bytes of the freecount. While sparse chunks can
> be enabled on previously unsupported fs, older kernel drivers cannot
> parse sparse inode records.
>
> Set the feature incompatible bit once a sparse inode chunk is allocated
> to prevent older XFS drivers from tripping over the new format.
>
> Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
> ---
> fs/xfs/libxfs/xfs_ialloc.c | 33 +++++++++++++++++++++++++++++++++
> 1 file changed, 33 insertions(+)
>
> diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
> index 4226b1b..4dd45c2 100644
> --- a/fs/xfs/libxfs/xfs_ialloc.c
> +++ b/fs/xfs/libxfs/xfs_ialloc.c
> @@ -407,6 +407,27 @@ error:
> return error;
> }
>
> +STATIC void
> +xfs_sbversion_add_spinodes(
> + struct xfs_trans *tp,
> + struct xfs_mount *mp)
> +{
> + if (xfs_sb_has_incompat_log_feature(&mp->m_sb,
> + XFS_SB_FEAT_INCOMPAT_SPINODES))
wrong function. xfs_sb_has_incompat_feature().
> + return;
> +
> + spin_lock(&mp->m_sb_lock);
> + if (xfs_sb_has_incompat_log_feature(&mp->m_sb,
> + XFS_SB_FEAT_INCOMPAT_SPINODES)) {
> + spin_unlock(&mp->m_sb_lock);
> + return;
> + }
> +
> + mp->m_sb.sb_features_incompat |= XFS_SB_FEAT_INCOMPAT_SPINODES;
> + spin_unlock(&mp->m_sb_lock);
> + xfs_mod_sb(tp, XFS_SB_FEATURES_INCOMPAT);
> +}
> +
> /*
> * Allocate new inodes in the allocation group specified by agbp.
> * Return 0 for success, else error code.
> @@ -631,6 +652,18 @@ xfs_ialloc_ag_alloc(
> if (error)
> return error;
> }
> +
> + /*
> + * Set an incompat feature bit as old drivers can't parse sparse
> + * records. Pre-sparse inode chunk drivers will include the
> + * holemask in the higher order freecount bits, resulting in a
> + * bogus value.
> + *
> + * XXX: when is this bit removed?
> + */
> + if (xfs_inobt_issparse(&rec))
> + xfs_sbversion_add_spinodes(tp, args.mp);
I'd like to avoid this dynamic feature bit adding if possible. Do we
really need it?
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
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