xfs: remove suport for filesystems without unwritten extent flag

The option to enable unwritten extents was made default in 2003,
removed from mkfs in 2007, and cannot be disabled in v5.  We also
rely on it for a lot of common functionality, so filesystems without
it will run a completely untested and buggy code path.  Enabling the
support also is a simple bit flip using xfs_db, so legacy file
systems can still be brought forward.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

3 files changed, 11 insertions, 23 deletions

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index a47670332326..da6b768664e3 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -4081,8 +4081,7 @@ xfs_bmapi_allocate(
 	 * extents to real extents when we're about to write the data.
 	 */
 	if ((!bma->wasdel || (bma->flags & XFS_BMAPI_COWFORK)) &&
-	    (bma->flags & XFS_BMAPI_PREALLOC) &&
-	    xfs_sb_version_hasextflgbit(&mp->m_sb))
+	    (bma->flags & XFS_BMAPI_PREALLOC))
 		bma->got.br_state = XFS_EXT_UNWRITTEN;
 
 	if (bma->wasdel)
@@ -5245,8 +5244,7 @@ __xfs_bunmapi(
 			 * unmapping part of it.  But we can't really
 			 * get rid of part of a realtime extent.
 			 */
-			if (del.br_state == XFS_EXT_UNWRITTEN ||
-			    !xfs_sb_version_hasextflgbit(&mp->m_sb)) {
+			if (del.br_state == XFS_EXT_UNWRITTEN) {
 				/*
 				 * This piece is unwritten, or we're not
 				 * using unwritten extents.  Skip over it.
@@ -5296,10 +5294,9 @@ __xfs_bunmapi(
 				del.br_blockcount -= mod;
 				del.br_startoff += mod;
 				del.br_startblock += mod;
-			} else if ((del.br_startoff == start &&
-				    (del.br_state == XFS_EXT_UNWRITTEN ||
-				     tp->t_blk_res == 0)) ||
-				   !xfs_sb_version_hasextflgbit(&mp->m_sb)) {
+			} else if (del.br_startoff == start &&
+				   (del.br_state == XFS_EXT_UNWRITTEN ||
+				    tp->t_blk_res == 0)) {
 				/*
 				 * Can't make it unwritten.  There isn't
 				 * a full extent here so just skip it.
@@ -6114,11 +6111,7 @@ xfs_bmap_validate_extent(
 		    XFS_FSB_TO_AGNO(mp, endfsb))
 			return __this_address;
 	}
-	if (irec->br_state != XFS_EXT_NORM) {
-		if (whichfork != XFS_DATA_FORK)
-			return __this_address;
-		if (!xfs_sb_version_hasextflgbit(&mp->m_sb))
-			return __this_address;
-	}
+	if (irec->br_state != XFS_EXT_NORM && whichfork != XFS_DATA_FORK)
+		return __this_address;
 	return NULL;
 }
diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
index afbe336600e1..9995d5ae380b 100644
--- a/fs/xfs/libxfs/xfs_format.h
+++ b/fs/xfs/libxfs/xfs_format.h
@@ -287,6 +287,8 @@ static inline bool xfs_sb_good_v4_features(struct xfs_sb *sbp)
 {
 	if (!(sbp->sb_versionnum & XFS_SB_VERSION_DIRV2BIT))
 		return false;
+	if (!(sbp->sb_versionnum & XFS_SB_VERSION_EXTFLGBIT))
+		return false;
 
 	/* check for unknown features in the fs */
 	if ((sbp->sb_versionnum & ~XFS_SB_VERSION_OKBITS) ||
@@ -357,12 +359,6 @@ static inline bool xfs_sb_version_haslogv2(struct xfs_sb *sbp)
 	       (sbp->sb_versionnum & XFS_SB_VERSION_LOGV2BIT);
 }
 
-static inline bool xfs_sb_version_hasextflgbit(struct xfs_sb *sbp)
-{
-	return XFS_SB_VERSION_NUM(sbp) == XFS_SB_VERSION_5 ||
-	       (sbp->sb_versionnum & XFS_SB_VERSION_EXTFLGBIT);
-}
-
 static inline bool xfs_sb_version_hassector(struct xfs_sb *sbp)
 {
 	return (sbp->sb_versionnum & XFS_SB_VERSION_SECTORBIT);
diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index 081f46e30556..b5a82acd7dfe 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -1115,7 +1115,8 @@ xfs_fs_geometry(
 
 	geo->version = XFS_FSOP_GEOM_VERSION;
 	geo->flags = XFS_FSOP_GEOM_FLAGS_NLINK |
-		     XFS_FSOP_GEOM_FLAGS_DIRV2;
+		     XFS_FSOP_GEOM_FLAGS_DIRV2 |
+		     XFS_FSOP_GEOM_FLAGS_EXTFLG;
 	if (xfs_sb_version_hasattr(sbp))
 		geo->flags |= XFS_FSOP_GEOM_FLAGS_ATTR;
 	if (xfs_sb_version_hasquota(sbp))
@@ -1124,8 +1125,6 @@ xfs_fs_geometry(
 		geo->flags |= XFS_FSOP_GEOM_FLAGS_IALIGN;
 	if (xfs_sb_version_hasdalign(sbp))
 		geo->flags |= XFS_FSOP_GEOM_FLAGS_DALIGN;
-	if (xfs_sb_version_hasextflgbit(sbp))
-		geo->flags |= XFS_FSOP_GEOM_FLAGS_EXTFLG;
 	if (xfs_sb_version_hassector(sbp))
 		geo->flags |= XFS_FSOP_GEOM_FLAGS_SECTOR;
 	if (xfs_sb_version_hasasciici(sbp))