--- httpd-2.2.6-patched/modules/cache/mod_disk_cache.c	2008-03-25 19:30:01.000000000 +0000
+++ httpd-2.2.6-patched/modules/cache/mod_disk_cache.c	2008-03-25 19:47:51.000000000 +0000
@@ -593,6 +593,7 @@ 
     dobj->updtimeout = conf->updtimeout;
     dobj->removedirs = conf->removedirs;
     dobj->header_only = r->header_only;
+    dobj->bytes_sent = 0;
 
     if(r->filename != NULL && strlen(r->filename) > 0) {
         char buf[34];
@@ -1506,6 +1507,7 @@ 
 {
     apr_bucket *e;
     disk_cache_object_t *dobj = (disk_cache_object_t*) h->cache_obj->vobj;
+    apr_off_t bytes_already_done;
 
     if(dobj->hfd != NULL) {
         /* Close header cache file, it won't be needed anymore */
@@ -1529,18 +1531,23 @@ 
     }
 
     /* Insert as much as possible as regular file (ie. sendfile():able) */
-    if(dobj->file_size > 0) {
-        if(apr_brigade_insert_file(bb, dobj->bfd, 0, 
-                                   dobj->file_size, p) == NULL) 
+    /* We need to make sure to skip the beginning of the file if we've
+       already sent some bytes, e.g., due to mod_proxy */
+    if(dobj->file_size > dobj->bytes_sent) {
+        if(apr_brigade_insert_file(bb, dobj->bfd, dobj->bytes_sent, 
+                                   dobj->file_size - dobj->bytes_sent, p) == NULL) 
         {
             return APR_ENOMEM;
         }
+        bytes_already_done = dobj->file_size;
+    } else {
+        bytes_already_done = dobj->bytes_sent;
     }
 
     /* Insert any remainder as read-while-caching bucket */
-    if(dobj->file_size < dobj->initial_size) {
-        if(diskcache_brigade_insert(bb, dobj->bfd, dobj->file_size, 
-                                    dobj->initial_size - dobj->file_size,
+    if(bytes_already_done < dobj->initial_size) {
+        if(diskcache_brigade_insert(bb, dobj->bfd, bytes_already_done, 
+                                    dobj->initial_size - bytes_already_done,
                                     dobj->updtimeout, p
                     ) == NULL) 
         {
@@ -2455,6 +2462,10 @@ 
     }
 
     /* Then, populate it with our cached instance */
+
+    /* in case we've already sent part, e.g. via mod_proxy */
+    dobj->bytes_sent = r->bytes_sent;
+
     rv = recall_body(h, r->pool, bb);
     if (rv != APR_SUCCESS) {
         ap_log_error(APLOG_MARK, APLOG_ERR, 0, r->server,
--- httpd-2.2.6-patched/modules/cache/mod_disk_cache.h	2008-03-25 19:30:01.000000000 +0000
+++ httpd-2.2.6-patched/modules/cache/mod_disk_cache.h	2008-03-25 19:34:03.000000000 +0000
@@ -124,6 +124,8 @@ 
     apr_interval_time_t updtimeout; /* Cache update timeout */
 
     disk_cache_info_t disk_info; /* Disk header information. */
+
+    apr_off_t bytes_sent; /* Copy of r->bytes_sent before calling recall_body */
 } disk_cache_object_t;