xfs: reserve v5 superblock read-only compat. feature bit for finobt (8e2c84df) · Commits · 戴 / test

Reserve a v5 read-only compatibility feature bit for the finobt and create the xfs_sb_version_hasfinobt() helper to determine whether an fs has the feature enabled. The finobt does not change existing on-disk structures, but must remain consistent with the ialloc btree. Modifications from older kernels would violate that constrant. Therefore, we restrict older kernels to read-only mounts of finobt-enabled filesystems. Note that this does not yet enable the ability to rw mount a finobt fs (by setting the feature bit in the XFS_SB_FEAT_RO_COMPAT_ALL mask). Signed-off-by:

Brian Foster <bfoster@redhat.com> Reviewed-by:

Dave Chinner <dchinner@redhat.com> Signed-off-by:

Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_sb.h

+7 −0

Original line number	Original line	Diff line number	Diff line
	@@ -587,6 +587,7 @@ xfs_sb_has_compat_feature(
	return (sbp->sb_features_compat & feature) != 0;		return (sbp->sb_features_compat & feature) != 0;
	}		}

			#define XFS_SB_FEAT_RO_COMPAT_FINOBT (1 << 0) /* free inode btree */
	#define XFS_SB_FEAT_RO_COMPAT_ALL 0		#define XFS_SB_FEAT_RO_COMPAT_ALL 0
	#define XFS_SB_FEAT_RO_COMPAT_UNKNOWN ~XFS_SB_FEAT_RO_COMPAT_ALL		#define XFS_SB_FEAT_RO_COMPAT_UNKNOWN ~XFS_SB_FEAT_RO_COMPAT_ALL
	static inline bool		static inline bool
	@@ -641,6 +642,12 @@ static inline int xfs_sb_version_hasftype(struct xfs_sb *sbp)
	(sbp->sb_features2 & XFS_SB_VERSION2_FTYPE));		(sbp->sb_features2 & XFS_SB_VERSION2_FTYPE));
	}		}

			static inline int xfs_sb_version_hasfinobt(xfs_sb_t *sbp)
			{
			return (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5) &&
			(sbp->sb_features_ro_compat & XFS_SB_FEAT_RO_COMPAT_FINOBT);
			}

	/*		/*
	* end of superblock version macros		* end of superblock version macros
	*/		*/

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