xfs: precalculate default inode attribute offset

Default attr fork offset is based on inode size, so is a fixed
geometry parameter of the inode. Move it to the xfs_ino_geometry
structure and stop calculating it on every call to
xfs_default_attroffset().
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Tested-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>

fs/xfs/libxfs/xfs_bmap.c

@@ -94,6 +94,15 @@ xfs_bmap_compute_maxlevels(
 	mp->m_bm_maxlevels[whichfork] = level;
 }
 
+unsigned int
+xfs_bmap_compute_attr_offset(
+	struct xfs_mount	*mp)
+{
+	if (mp->m_sb.sb_inodesize == 256)
+		return XFS_LITINO(mp) - XFS_BMDR_SPACE_CALC(MINABTPTRS);
+	return XFS_BMDR_SPACE_CALC(6 * MINABTPTRS);
+}
+
 STATIC int				/* error */
 xfs_bmbt_lookup_eq(
 	struct xfs_btree_cur	*cur,
@@ -192,19 +201,9 @@ uint
 xfs_default_attroffset(
 	struct xfs_inode	*ip)
 {
-	struct xfs_mount	*mp = ip->i_mount;
-	uint			offset;
-
 	if (ip->i_df.if_format == XFS_DINODE_FMT_DEV)
 		return roundup(sizeof(xfs_dev_t), 8);
-
-	if (mp->m_sb.sb_inodesize == 256)
-		offset = XFS_LITINO(mp) - XFS_BMDR_SPACE_CALC(MINABTPTRS);
-	else
-		offset = XFS_BMDR_SPACE_CALC(6 * MINABTPTRS);
-
-	ASSERT(offset < XFS_LITINO(mp));
-	return offset;
+	return M_IGEO(ip->i_mount)->attr_fork_offset;
 }
 
 /*

fs/xfs/libxfs/xfs_bmap.h

@@ -185,6 +185,7 @@ static inline bool xfs_bmap_is_written_extent(struct xfs_bmbt_irec *irec)
 
 void	xfs_trim_extent(struct xfs_bmbt_irec *irec, xfs_fileoff_t bno,
 		xfs_filblks_t len);
+unsigned int xfs_bmap_compute_attr_offset(struct xfs_mount *mp);
 int	xfs_bmap_add_attrfork(struct xfs_inode *ip, int size, int rsvd);
 int	xfs_bmap_set_attrforkoff(struct xfs_inode *ip, int size, int *version);
 void	xfs_bmap_local_to_extents_empty(struct xfs_trans *tp,

fs/xfs/libxfs/xfs_shared.h

@@ -176,8 +176,12 @@ struct xfs_ino_geometry {
 
 	unsigned int	agino_log;	/* #bits for agino in inum */
 
+	/* precomputed default inode attribute fork offset */
+	unsigned int	attr_fork_offset;
+
 	/* precomputed value for di_flags2 */
 	uint64_t	new_diflags2;
+
 };
 
 #endif /* __XFS_SHARED_H__ */

fs/xfs/xfs_mount.c

@@ -675,6 +675,18 @@ xfs_unmount_flush_inodes(
 	xfs_health_unmount(mp);
 }
 
+static void
+xfs_mount_setup_inode_geom(
+	struct xfs_mount	*mp)
+{
+	struct xfs_ino_geometry *igeo = M_IGEO(mp);
+
+	igeo->attr_fork_offset = xfs_bmap_compute_attr_offset(mp);
+	ASSERT(igeo->attr_fork_offset < XFS_LITINO(mp));
+
+	xfs_ialloc_setup_geometry(mp);
+}
+
 /*
  * This function does the following on an initial mount of a file system:
  *	- reads the superblock from disk and init the mount struct
@@ -758,7 +770,7 @@ xfs_mountfs(
 	xfs_alloc_compute_maxlevels(mp);
 	xfs_bmap_compute_maxlevels(mp, XFS_DATA_FORK);
 	xfs_bmap_compute_maxlevels(mp, XFS_ATTR_FORK);
-	xfs_ialloc_setup_geometry(mp);
+	xfs_mount_setup_inode_geom(mp);
 	xfs_rmapbt_compute_maxlevels(mp);
 	xfs_refcountbt_compute_maxlevels(mp);