Re: [PATCH V8 08/19] xfs: Introduce XFS_SB_FEAT_INCOMPAT_NREXT64 and associated per-fs feature bit

Dave Chinner
2022-03-24T21:37:25Z

On Mon, Mar 21, 2022 at 10:47:39AM +0530, Chandan Babu R wrote:
> XFS_SB_FEAT_INCOMPAT_NREXT64 incompat feature bit will be set on filesystems
> which support large per-inode extent counters. This commit defines the new
> incompat feature bit and the corresponding per-fs feature bit (along with
> inline functions to work on it).
>
> Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> Signed-off-by: Chandan Babu R <chandan.babu@oracle.com>
> ---
> fs/xfs/libxfs/xfs_format.h | 1 +
> fs/xfs/libxfs/xfs_sb.c | 3 +++
> fs/xfs/xfs_mount.h | 2 ++
> 3 files changed, 6 insertions(+)
>
> diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
> index b5e9256d6d32..64ff0c310696 100644
> --- a/fs/xfs/libxfs/xfs_format.h
> +++ b/fs/xfs/libxfs/xfs_format.h
> @@ -372,6 +372,7 @@ xfs_sb_has_ro_compat_feature(
> #define XFS_SB_FEAT_INCOMPAT_META_UUID (1 << 2) /* metadata UUID */
> #define XFS_SB_FEAT_INCOMPAT_BIGTIME (1 << 3) /* large timestamps */
> #define XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR (1 << 4) /* needs xfs_repair */
> +#define XFS_SB_FEAT_INCOMPAT_NREXT64 (1 << 5) /* large extent counters */
> #define XFS_SB_FEAT_INCOMPAT_ALL \
> (XFS_SB_FEAT_INCOMPAT_FTYPE| \
> XFS_SB_FEAT_INCOMPAT_SPINODES| \
> diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
> index f4e84aa1d50a..bd632389ae92 100644
> --- a/fs/xfs/libxfs/xfs_sb.c
> +++ b/fs/xfs/libxfs/xfs_sb.c
> @@ -124,6 +124,9 @@ xfs_sb_version_to_features(
> features |= XFS_FEAT_BIGTIME;
> if (sbp->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_NEEDSREPAIR)
> features |= XFS_FEAT_NEEDSREPAIR;
> + if (sbp->sb_features_incompat & XFS_SB_FEAT_INCOMPAT_NREXT64)
> + features |= XFS_FEAT_NREXT64;
> +

Shouldn't enabling the feature be the last patch in the series, once
all the infrastructure to support the feature is in place? i.e. if
someone does a bisect on a XFS_FEAT_NREXT64 enabled filesystem, they
can land in the middle of this series where the fs tries to use
XFS_FEAT_NREXT64 but the functionality is not complete.

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com