+xfs_attr_shortform_bytesfit(xfs_inode_t *dp, int bytes)
+{
+ int offset;
+ int minforkoff; /* lower limit on valid forkoff locations */
+ int maxforkoff; /* upper limit on valid forkoff locations */
+ int dsize;
+ xfs_mount_t *mp = dp->i_mount;
+
+ offset = (XFS_LITINO(mp) - bytes) >> 3; /* rounded down */
+
+ switch (dp->i_d.di_format) {
+ case XFS_DINODE_FMT_DEV:
+ minforkoff = roundup(sizeof(xfs_dev_t), 8) >> 3;
+ return (offset >= minforkoff) ? minforkoff : 0;
+ case XFS_DINODE_FMT_UUID:
+ minforkoff = roundup(sizeof(uuid_t), 8) >> 3;
+ return (offset >= minforkoff) ? minforkoff : 0;
+ }
+
+ if (!(mp->m_flags & XFS_MOUNT_ATTR2)) {
+ if (bytes <= XFS_IFORK_ASIZE(dp))
+ return mp->m_attroffset >> 3;
+ return 0;
+ }
+
+ 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));
+ minforkoff = roundup(minforkoff, 8) >> 3;
+
+ /* attr fork btree root can have at least this many key/ptr pairs */
+ maxforkoff = XFS_LITINO(mp) - XFS_BMDR_SPACE_CALC(MINABTPTRS);
+ maxforkoff = maxforkoff >> 3; /* rounded down */
+
+ if (offset >= minforkoff && offset < maxforkoff)
+ return offset;
+ if (offset >= maxforkoff)
+ return maxforkoff;
+ return 0;
+}
+
+/*
+ * Switch on the ATTR2 superblock bit (implies also FEATURES2)
+ */
+STATIC void
+xfs_sbversion_add_attr2(xfs_mount_t *mp, xfs_trans_t *tp)
+{
+ unsigned long s;
+
+ if ((mp->m_flags & XFS_MOUNT_ATTR2) &&
+ !(XFS_SB_VERSION_HASATTR2(&mp->m_sb))) {
+ s = XFS_SB_LOCK(mp);
+ if (!XFS_SB_VERSION_HASATTR2(&mp->m_sb)) {
+ XFS_SB_VERSION_ADDATTR2(&mp->m_sb);
+ XFS_SB_UNLOCK(mp, s);
+ xfs_mod_sb(tp, XFS_SB_VERSIONNUM | XFS_SB_FEATURES2);
+ } else
+ XFS_SB_UNLOCK(mp, s);
+ }
+}
+
+/*
+ * Create the initial contents of a shortform attribute list.
+ */
+void