xfsrestore: fix 2GB directory dump limitation for multi-stream

[Rich Johnston <rjohnston@xxxxxxx>]

The drive_simple restore path has a 2GB directory limit. Instead of
ASSERTing if nreadneeded64 is greater than INTGENMAX (2GB), add a loop
to handle it.

Signed-off-by: Rich Johnston <rjohnston@xxxxxxx>
---
 common/drive_simple.c |   24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

Index: b/common/drive_simple.c
===================================================================
--- a/common/drive_simple.c
+++ b/common/drive_simple.c
@@ -765,18 +765,20 @@ do_seek_mark( drive_t *drivep, drive_mar
        /* use read_buf util func to eat up difference
         */
        nreadneeded64 = mark - strmoff;
-       ASSERT( nreadneeded64 <= INTGENMAX );
-       nreadneeded = ( intgen_t )nreadneeded64;
-       nread = read_buf( 0,
-                         ( size_t )nreadneeded,
-                         ( void * )drivep,
-                         ( rfp_t )drivep->d_opsp->do_read,
-                         ( rrbfp_t )drivep->d_opsp->do_return_read_buf,
-                         &rval );
-       if  ( rval ) {
-               return rval;
+       while ( nreadneeded64 > 0 ) {
+               if ( nreadneeded64 > INTGENMAX )
+                       nreadneeded = INTGENMAX;
+               else
+                       nreadneeded = ( intgen_t )nreadneeded64;
+               nread = read_buf( 0, nreadneeded, drivep,
+                                 ( rfp_t )drivep->d_opsp->do_read,
+                               ( rrbfp_t )drivep->d_opsp->do_return_read_buf,
+                                 &rval );
+               if  ( rval ) {
+                       return rval;
+               }
+               nreadneeded64 -= nread;
        }
-       ASSERT( nread == nreadneeded );
 
        /* verify we are on the mark
         */