X-Git-Url: http://git.tuebingen.mpg.de/?a=blobdiff_plain;f=vss.c;h=db1beeba17d080e08f306830bc0ce9dd0b7bf5e0;hb=71bcf40d3aeed43884c8db9e44d5eade41f22db2;hp=e833543e785788876af91d691b73cf8876899de3;hpb=7bba6232e873b7a6acc95ac05b4e333f86a51a46;p=paraslash.git

diff --git a/vss.c b/vss.c
index e833543e..db1beeba 100644
--- a/vss.c
+++ b/vss.c
@@ -132,6 +132,7 @@ struct fec_group {
 	uint16_t slice_bytes;
 };
 
+/** A FEC client is always in one of these states. */
 enum fec_client_state {
 	FEC_STATE_NONE = 0,	/**< not initialized and not enabled */
 	FEC_STATE_DISABLED,	/**< temporarily disabled */
@@ -1078,8 +1079,6 @@ static void vss_send(struct vss_task *vsst)
 			senders[i].send(mmd->current_chunk, mmd->chunks_sent,
 				buf, len, vsst->header_buf, vsst->header_len);
 		}
-		mmd->chunks_sent++;
-		mmd->current_chunk++;
 		/*
 		 * Prefault next chunk(s)
 		 *
@@ -1092,11 +1091,15 @@ static void vss_send(struct vss_task *vsst)
 		 * eliminate the delays completely. Moreover, it is supported
 		 * only on Linux. So we do our own read-ahead here.
 		 */
-		buf += len;
-		for (i = 0; i < 5 && buf < vsst->map + mmd->size; i++) {
-			__a_unused volatile char x = *buf;
-			buf += 4096;
+		if (mmd->current_chunk > 0) { /* chunk 0 might be on the heap */
+			buf += len;
+			for (i = 0; i < 5 && buf < vsst->map + mmd->size; i++) {
+				__a_unused volatile char x = *buf;
+				buf += 4096;
+			}
 		}
+		mmd->chunks_sent++;
+		mmd->current_chunk++;
 	}
 }