struct xfs_bmbt_irec    *irec)
 {
        struct xfs_mount        *mp = ip->i_mount;
-       xfs_fsblock_t           endfsb;
-       bool                    isrt;
 
-       if (irec->br_startblock + irec->br_blockcount <= irec->br_startblock)
-               return __this_address;
        if (irec->br_startoff + irec->br_blockcount <= irec->br_startoff)
                return __this_address;
 
-       isrt = XFS_IS_REALTIME_INODE(ip);
-       endfsb = irec->br_startblock + irec->br_blockcount - 1;
-       if (isrt && whichfork == XFS_DATA_FORK) {
-               if (!xfs_verify_rtbno(mp, irec->br_startblock))
-                       return __this_address;
-               if (!xfs_verify_rtbno(mp, endfsb))
+       if (XFS_IS_REALTIME_INODE(ip) && whichfork == XFS_DATA_FORK) {
+               if (!xfs_verify_rtext(mp, irec->br_startblock,
+                                         irec->br_blockcount))
                        return __this_address;
        } else {
                if (!xfs_verify_fsbext(mp, irec->br_startblock,
 
        return rtbno < mp->m_sb.sb_rblocks;
 }
 
+/* Verify that a realtime device extent is fully contained inside the volume. */
+bool
+xfs_verify_rtext(
+       struct xfs_mount        *mp,
+       xfs_rtblock_t           rtbno,
+       xfs_rtblock_t           len)
+{
+       if (rtbno + len <= rtbno)
+               return false;
+
+       if (!xfs_verify_rtbno(mp, rtbno))
+               return false;
+
+       return xfs_verify_rtbno(mp, rtbno + len - 1);
+}
+
 /* Calculate the range of valid icount values. */
 void
 xfs_icount_range(
 
 bool xfs_internal_inum(struct xfs_mount *mp, xfs_ino_t ino);
 bool xfs_verify_dir_ino(struct xfs_mount *mp, xfs_ino_t ino);
 bool xfs_verify_rtbno(struct xfs_mount *mp, xfs_rtblock_t rtbno);
+bool xfs_verify_rtext(struct xfs_mount *mp, xfs_rtblock_t rtbno,
+               xfs_rtblock_t len);
 bool xfs_verify_icount(struct xfs_mount *mp, unsigned long long icount);
 bool xfs_verify_dablk(struct xfs_mount *mp, xfs_fileoff_t off);
 void xfs_icount_range(struct xfs_mount *mp, unsigned long long *min,
 
        struct xfs_bmbt_irec    *irec)
 {
        struct xfs_mount        *mp = info->sc->mp;
-       xfs_filblks_t           end;
        int                     error = 0;
 
        /*
        if (irec->br_blockcount > MAXEXTLEN)
                xchk_fblock_set_corrupt(info->sc, info->whichfork,
                                irec->br_startoff);
-       if (irec->br_startblock + irec->br_blockcount <= irec->br_startblock)
-               xchk_fblock_set_corrupt(info->sc, info->whichfork,
-                               irec->br_startoff);
-       end = irec->br_startblock + irec->br_blockcount - 1;
        if (info->is_rt &&
-           (!xfs_verify_rtbno(mp, irec->br_startblock) ||
-            !xfs_verify_rtbno(mp, end)))
+           !xfs_verify_rtext(mp, irec->br_startblock, irec->br_blockcount))
                xchk_fblock_set_corrupt(info->sc, info->whichfork,
                                irec->br_startoff);
        if (!info->is_rt &&
 
        startblock = rec->ar_startext * tp->t_mountp->m_sb.sb_rextsize;
        blockcount = rec->ar_extcount * tp->t_mountp->m_sb.sb_rextsize;
 
-       if (startblock + blockcount <= startblock ||
-           !xfs_verify_rtbno(sc->mp, startblock) ||
-           !xfs_verify_rtbno(sc->mp, startblock + blockcount - 1))
+       if (!xfs_verify_rtext(sc->mp, startblock, blockcount))
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
        return 0;
 }