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authorBrian Foster <bfoster@redhat.com>2014-04-24 02:00:52 -0400
committerDave Chinner <david@fromorbit.com>2014-04-24 02:00:52 -0400
commit8e2c84df20aa66ae9a6ee32831a9c622f4823118 (patch)
tree8bd22beb613b809dbf75531b56fbb6c9ad0f6d6a
parent57bd3dbe4059c6fff7e39927e5aa789dfb2585b9 (diff)
xfs: reserve v5 superblock read-only compat. feature bit for finobt
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>
-rw-r--r--fs/xfs/xfs_sb.h7
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/xfs/xfs_sb.h b/fs/xfs/xfs_sb.h
index f7b2fe77c5a5..7f53a858e85b 100644
--- a/fs/xfs/xfs_sb.h
+++ b/fs/xfs/xfs_sb.h
@@ -587,6 +587,7 @@ xfs_sb_has_compat_feature(
587 return (sbp->sb_features_compat & feature) != 0; 587 return (sbp->sb_features_compat & feature) != 0;
588} 588}
589 589
590#define XFS_SB_FEAT_RO_COMPAT_FINOBT (1 << 0) /* free inode btree */
590#define XFS_SB_FEAT_RO_COMPAT_ALL 0 591#define XFS_SB_FEAT_RO_COMPAT_ALL 0
591#define XFS_SB_FEAT_RO_COMPAT_UNKNOWN ~XFS_SB_FEAT_RO_COMPAT_ALL 592#define XFS_SB_FEAT_RO_COMPAT_UNKNOWN ~XFS_SB_FEAT_RO_COMPAT_ALL
592static inline bool 593static inline bool
@@ -641,6 +642,12 @@ static inline int xfs_sb_version_hasftype(struct xfs_sb *sbp)
641 (sbp->sb_features2 & XFS_SB_VERSION2_FTYPE)); 642 (sbp->sb_features2 & XFS_SB_VERSION2_FTYPE));
642} 643}
643 644
645static inline int xfs_sb_version_hasfinobt(xfs_sb_t *sbp)
646{
647 return (XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5) &&
648 (sbp->sb_features_ro_compat & XFS_SB_FEAT_RO_COMPAT_FINOBT);
649}
650
644/* 651/*
645 * end of superblock version macros 652 * end of superblock version macros
646 */ 653 */