+ dsize = dp->i_df.if_bytes;
+
+ switch (dp->i_d.di_format) {
+ case XFS_DINODE_FMT_EXTENTS:
+ /*
+ * If there is no attr fork and the data fork is extents,
+ * determine if creating the default attr fork will result
+ * in the extents form migrating to btree. If so, the
+ * minimum offset only needs to be the space required for
+ * the btree root.
+ */
+ if (!dp->i_d.di_forkoff && dp->i_df.if_bytes > mp->m_attroffset)
+ dsize = XFS_BMDR_SPACE_CALC(MINDBTPTRS);
+ break;
+
+ case XFS_DINODE_FMT_BTREE:
+ /*
+ * If have data btree then keep forkoff if we have one,
+ * otherwise we are adding a new attr, so then we set
+ * minforkoff to where the btree root can finish so we have
+ * plenty of room for attrs
+ */
+ if (dp->i_d.di_forkoff) {
+ if (offset < dp->i_d.di_forkoff)
+ return 0;
+ else
+ return dp->i_d.di_forkoff;
+ } else
+ dsize = XFS_BMAP_BROOT_SPACE(dp->i_df.if_broot);
+ break;
+ }
+
+ /*
+ * A data fork btree root must have space for at least
+ * MINDBTPTRS key/ptr pairs if the data fork is small or empty.
+ */
+ minforkoff = MAX(dsize, XFS_BMDR_SPACE_CALC(MINDBTPTRS));