From 8e2c84df20aa66ae9a6ee32831a9c622f4823118 Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Thu, 24 Apr 2014 16:00:52 +1000 Subject: [PATCH] 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 Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner --- fs/xfs/xfs_sb.h | 7 +++++++ 1 file changed, 7 insertions(+) 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( 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_UNKNOWN ~XFS_SB_FEAT_RO_COMPAT_ALL 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)); } +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 */ -- 2.34.1